CA1103424A - Chalcogenides and method of preparation - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE Chalcogenides having a crystalline size of less than 0.1 micron of the formula MXy wherein M is a metal selected from the group consisting of Group IVb, Vb, molybdenum and tungsten transition metals of the Periodic Table of the Elements, x is a chalcongenide selected from the group consisting of sulfur, selenium and tellurium, and y is a number ranging from about 2 to about 4. Chalcogenide intercalates are useful as, for example, lubricants, battery cathodes and superconductors.

Description

1 The Group IVb, Vb and molybdenum and tungsten trans-

2 ition metals di and poly-chalcogenides (MXy wherein M is Ti,

3 Zr, Hf, V, Nb, Ta; Mo and W and X is S, Se and Te and y is

4 from about 2 to 4) have traditionally been prepared, when preparation was possible at all, by high temperature reac-6 tions. The di- and poly-chalcogenides have attracted great 7 interest because of ~heir highly anisotropic properties and 8 intercalation properties. Intercalates made using various 9 chalcogenides are useful as lubricants, battery cathodes and superconductors. (See Gamble et al U.S~ Patent 3~766,064) 11 However, a major drawback in the use of chalcogenides is the 12 diffi ulty encoun~ered in their preparationO These ~aterials 13 of composition MX2 cannot be prepared in aqueous solution be-14 cause o the susceptibility of the M~3~4~5 ion to hydrolysis or to ormation of complex oxo iorls (Cotton and Wilkenson9 16 "Advanced Inorganic Chemistry" 2d ed. Interscience, New York, 7 1966)o 18 By comparison, low temperature precipitation o~
19 solids from solution has the advantage o~ low cost and also permits preparation of a wide variety of products of varied 21 properties not accessible by other meansO
22 Finely divided, large surface area, small crystal-23 lite diameter, i.e. 0.1 micron (1000 A), preferably less than 24 0,05 micron (500 A) and stoichiometric di- and polychalco-genides of the formula ~ wherein M is a metal selected 26 from the group consisting of Group IVb, Vb and molybdenum 27 and tung~ten transition metals of the Periodic Table of the 28 Elements, X is a chalcogenide selected from the group con-29 sisting of sulfur, selenium and tellurium and y is a number ranglng from about 2 to about 4, are prepared by the low 31 temperature nonaqueous precipitation of said MXy compounds 32 from solutions comprising mix~ures of the salts o said 1 Group IVb, Vb and molybdenum and tungsten transition metalæ, 2 common anions of ~he salts being halide, ~cetate, carboxylate, 3 perfluorocarboxylate, acetylacetonate, hexafluoroacetonate, 4 sulate, nitrate, preferably chloride, etc. with solutions s of or slurries of sources o sulfidep selenide or telluride 6 ions. The products o the low temperature nonaqueous pre-7 cipitation are distinguished from materials prepared by high 8 temperature (greater than 400C.) methods of the prior art 9 by exhibiting markedly different surface area and crystal-0 linity characteristics. A number of compounds of the formula 11 MXy wherein the constituent~s are as defined above may be 12 prepared via the low temperature nonaqueous techniques dis-13 closed which cannot be synthesized via the methods of the 14 prior art, i.e. aqueous methods or high temperature methods.
VS2 is one such compound which cannot be prepared by methods 16 common in the prior art. Preferred compounds are TiS2, 17 ZxS2~ HfS2, VS2, N~S2, TaS2 and MoS2.
18 A method for the preparation of di- and polychalco-19 genides and stoichiometric di- and poly-chalcogenides com-prises preparing a nonaqueous reactive solution or slurry 21 wherein is added (13 a transition metal salt, the transition 22 metal being selected from the group consisting o Group IVh, 23 Vb and molybdenum and tungsten of the Periodic Table and the 24 ~alt anion being selected from the group consisting of halide, acetate, carboxylate, perfluorocarboxylate3 acetyl-26 acetonate, hexafluoroacetylacetonate and (2) a source of 27 sulfide, selenide and/or telluride ions, said sources con-28 venientl~ being Li2S, hydrosulfide salts (i.e. NaHS, NH4HS) 3 29 (NH4)2S, Na2S, Li2Se, Li2Te, (NH4)2Se, (RNH3)2S, (R3R'NH2)2S, (R,R',R"NH)2S wherein R, R', R" are the same or different and 31 are selected from the group consisting of Cl-C~0 alkyl pre-32 ferably Cl to C8 or C6-C20 aryl, preferably C6 to Cl2, and 1 a nonaqueous solvent selected rom the group conslsting of 2 ethers of from C4 to C8; acetonitrile~ benzonitrile, di-3 methylformamide (DMF), l,2-dime~hoxyethane propylene carbon-4 ate, aromatics of C6-C20 carbons, preferably C6 to Cl2, ammonia, molten sulfur, diglyme, sulfur dio2ide, ethylace-6 tate, esters of from C4 to C89 sulfolane, tributylphosphate, 7 anhydrous acids such as formic acid, glacial acetic acid, 8 alkylhalides of from Cl to C2O9 preferably Cl to C5 and es of from C6 to C20~ preferably C6 to ClO, pyridine 0 propionitrile, N-methylformamide, dimethylsulfite, Cl-C30 11 amines, preferably Cl to C~09 C5~Cl2 alkanes, preferably - .
12 Cs-C8O The solvents of choice are tetrahydrofuran (THF)g 13 dimethylformamide (DMF), chlorobenzene, chloroform, pyridine 4 and acetone. Alternatlvely, ~he reaction may be run neat, that is, in the absence of any solvent. The reaction pro 16 ceeds spontaneously upon mixing at low temperàture~ prefer~
17 ably less than 400~C O but greater than -78~Go 9 and at atmos-18 pheric pressure The products may be isolated by filtering, 19 washing with excess solvents or by pumplng off the anion salts if they are volatile. In ~tuation~ wherein the sulfide, 21 selenide and/or telluride ion sources are already solutions, 22 no additional solvent is needed during the course-of the re-23 action although a volume of nonaqueous solvent (iOeO one 24 which does not offer or accept protons) may be added so as to facilitate product isolationO
26 The reaction which takes place is ~ nonaqueous ~l~
; 27 MZ4 ~ ~A2X . ~ X2 1-4AZ
28 solvent or neat 29 M ~ IVb, Vb or molybendum or tungsten transition metals;
A - alkali metal, NH~, R9RI,R"NH~, R,RINH2~, or other cat-31 ion as defined above; Z = convenient anion such as Cl, Br, 32 I~ acetate, carbo~ylate, nitrate, etc., as recited above;

3 ~

1 X = sulfur, selenium ~r tellurium.
2 Any convenient source of M~2 ~ ~5, preferably M+4 3 and M~5 can be used. Complexes formed in solution which can 4 be isolated as solids may be used as M~4 source. I~ some cases (such as Nb and Ta) a pentavalent salt may be used di-6 rectly because reduction of M~5 to Mt4 occurs, for example 7 NbC15 + 205 Li2S ~ -~ NbS2 ~ +5LiC1 ~ 0O5 S
8 The transition metal salts are desirably, although 9 not necessarily, soluble in organic solvents such as THF
since it is possible to conduct the reaction neat in all 11 cases. Therefore, solution concentrations are not cri~ical.
12 Anions which are envisioned 2S generating the metal salt, 3 are selected from the group consisting o halides, selected from the group consisting ~f fluvrineg ~lorine~ bromine and iodine, acetates, carboxylates, perfluorocarboxylates, amines, 16 acetylaceton~tes, hexafluoroacetylacetonates and nitrates, sulfates, wherein in all cases, the carbonaceous moiety of 18 the anion is a Cl to C8 hydrocarbon or fluorocarbon, prefer-19 ably a Cl to C3 hydrocarbon or fluorocarbonO
The reaction is normally ~ut no~ necessarily, con-21 ducted in the absence of an excess of sulfide, selenide or 22 telluride, although other starting ma~erials may be present 23 in excess. Since particle size depends on the rate of mixing 24 of reagents, the reaction may be allowed to proceed instantly, upon total admixture of one reagent to the reaction solution 26 yielding fine products or1 upon the measured addition of 27 small increments of one reagent to the reaction solution, 28 the reaction not achieving totality or several days.
29 The temperature o the reaction may range from -78 to 400C., preerably 0 to 400C~, more preferably 31 ambient (25C.) to 300C. These temperatures are markedly 32 lower than those needed when preparing dichalcogenides via l solid sta~e or gas phase methods wherein reaction temper~-2 tures up to and exceeding 1000C. are commonplace.
3 The products obtained from the low temperature 4 nonaqueous precipitatlon technique are di- and poly-chalco-genide, particularly di-chalcogenides and more particularly, 6 disulfides~ and have unique proper~iesO The products may 7 also be stoichiome~ric in character. For exanple, stoichio-8 metric NbS~ is difficult and/or impossible to prep~re and 9 stoichiometric VS2 is impussible ~ prepare by high temper-ature methodsO The particle size and crystallinity of these ll materials can be greatly varied by practicing the prepara-12 tive methods of the instant invention Small single crystals 13 or high surface area powders which are amorphous to X-ray 14 ~iOe. give no X-ray pattern) can be obtainedO Lack of X-ray pattern indicates a crystallite slæe of less than 0O05 micron 16 (500A~o Surface areas can be raised to the point where the 7 di-chalcogenide will remain suspended in solution and homo-18 geneous dispersions crea~edO This effect can be increased 19 by using more polar nonaqueous solvents ~uch as DMF or basic solvents such as pyr~dine which have a natural tendency to 21 attach to ~hè sulfur layers and cause dispersionsO These 22 same solvents are those which tend to ~ntercalate in crystal-23 line transltlon metal di~chalcogenides~ See Gamble et al, 24 U.S. Patent 3~766,064 for a list of such intercalation ma~er-ials. Such disper~ions can be gelled by proper variation of 26 conditions or adsorbed on basic substrates such as CaO. The 27 materials prepared by the process of the instant invention 28 have utilit~ as electrodes, catalysts, and are useful in the 29 preparation of intercalation compounds which are then useful as lubricants and superconductorsO
31 The above mention~d preparation method allows one 32 to choose compounds from a wide range of particle size, crys-3 ~ ~

1 tallinity and surface area. Solids may be prepared which 2 have the following properties.
3 A. High surface areaj small particle size and 4 amo~phous crystallinity. Such characteristics are achieved by Us2 of a solvent which may have the ability to form inter-6 calation complexes with the chalcogenide. Alternatively, 7 chalcogenides formed neat or in the absence of an intercala-8 tion solvent may be treated with an intercalate to achieve 9 the same result. Such intercalates may be a strong Lewis lo base such as pyridine, ammonia, Cl-C20 amines, aldehydes, 11 ketones, amides3 heterocyclic bases9 amidines,~anilines and 12 ethers. The intercalated chalcogenide is then subjected to 13 heat treatin~ at between 7S-200C. with pumping under vacuum 14 when necessary to drive off the lntercalating solvent leaving a high surface area, small particle s~ze, amorphous chalco-16 genide. Example: TiS2 prepared from THF and treated with 17 pyridine (intercalate pyridine and then drive lt out at 150C.) 18 gave an amorphous X-ray pattern w~ich indica~Qs a crystallite 19 size of at least less than 0.1 micron and a Brunauer, Emmett and Teller (BET) surface area of 100 m2/gm.
21 B. Low surface area, small particle size and amor- ~ -22 phous crystallinity. Example: The same TiS2 as men~ioned 23 in (A) if not treated wi~h pyridine gave an amorphous X-ray 24 pattern and a BET surface area of 10 m2/gm.
C. Low surface area, moderate particle size and 26 high crystallinity, E~ample: TiS2 prepared from refluxing 27 acetonitrile yielded a TiS2 X-ray pattern. The crystallin-28 ity of all materials can further be improved by annealing 29 products.
D. Homogeneous dispersions: conditions can be 31 arranged as above so that all or part of the di-chalcogen-3~ ides remains in suspension a8 a homogeneous dispersion. Such 1 materials can be removed by addition of a basic solid such 2 as CaO, Example. TiS~ prepared in propylene carbonate will 3 result in a dark brown opaque dispersion of TiS2o The TiS2 4 may be absorbed by shaking the dl.spersion with CaO which is dark brown when dried, Correspondingly, the original solu-6 tion is clear after treatment with CaOO
7 Eo High surace area compositeO Di-chalcogenide/
8 metal oxide solids. COmpOBite materia~s may be prepared 9 with the di- or poly-chal ogenLde being absorbed on a metal 0 oxide due to ~he Lewis acid nature of the calcogenide.
11 Example The TiS2~CaO material men~ioned in Eæample Do 12 Fo Gels and Glasseso Gels containing the di- :
13 chalcogenide6 may be produced by preparatlon in certain 4 aminesl such as trihexylamine~ The gels produced yield glasses when the solvents are removedO ExampleD See Example 16 8.
7 The precipitation in nonalqueous solution causes 18 the formation of stoichiometric products and effects reac-19 tions by virtue o ~he formation o insoluble precipitates, which ~eactions are incomplete at higher ~emperatures in 21 aqueous or solid state systems, 22 TiS2 may be prepared at from 450~Co to 600~C. by 23 the reaction in t~e gas phase of TiCl~ and H2S. However, 24 the efficiency of the reaction drops off at lower tempera-tures because the reaction is reversible.
26 TiC14 ~ H2~ ~ TiS2 ~ 4 HCl 27 Thus, H2S is not a practical sulfiding agent at temperatures 28 less than 400C.
29 When ~he reaction is conduc~ed in nonaqueous solu-tion at low temperature, however, the formation of insoluble 31 precipitates causes the reaction to be irreversible and 32 quantitative to TiS2o The presence of a chalcogenide ~alt 3 ~ ~

1 as an intermediate is importan-t because H2S bubbled through 2 a solution of TiC14 at room temperature will not produce a 3 reaction. However, if NH3 gas is first bubbled through the 4 solution the passing of H2S through the ammonia rich solu- -tion causes TlS2 to precipitateO This is due ~o the forma-6 tion of (NH4)2S or (NH43HS as an intermediate and (NH4)Cl 7 is the side product resulting from ion exchangeO Thus, NH3 8 mediates the reaction although (NH432S is not necessarily 9 actually isolated~ If NH3 and H2S are first coreacted, the intermediate salt is formedO
ll The pro~uct MXy wherein M and X are as previously 12 described and y ranges from about 2 to about 4 inclusive, 3 preferably 2, is separated from the anion salt~ which are 4 co-formed, by filtering and using excess solvent or by pump-ing off the anion s~lts if t~ey are volatileO If LiCl is 16 the product anion salt copreclpitat:ed~ excess solvent will 17 dissolve ito If NH4Cl is the coproduct3 pumping under vacu-l8 um will remove it (or washing may be used)~ However, pump-l9 ing under vacuum may cause sulfur t:o be removed from the lattice to a greater or lesser extentO For e~ample, VS2 is 21 not stable at higher ~emperaturesO Pumping9 as purification, 22 utilized for VS~ at 150Co will cause sulfur to be removed3 23 which sulfur was supporting t~e 102 stoichiomet.ry of the 24 starting ~S2, thereby providing a route to higher surface area, sulfur-deficient compoundsO
26 If the excess solvent used and coproduct generated 27 in the formation of compounds of the formula ~ are not 28 removed, the combination of the compounds of the formula 29 MXy and the coproducts constitute a battery system in which the coproducts may functi.on as the electrolyteO
31 For example, in a system generating TiS2 as pro-32 duct, the starting materials are TiCl~ and a sulfur source _ g 1 such as Li2S. Typically, the electrolyte involves the lith-2 ium salt of a strong acid (anion ~ PF6, ~ BF4, ~SO3CF3, 3 etc.) ~n an organic solvent such as DME, dioxolane or other 4 ethers or mixtures thereof 9 the requirement being that the salt has sufficient solubility in the solvent to behave as 6 a good Lif conductor. The Ti+4 salt o the desired electro-7 lytic anion ( ~) pF6, ~3 BF4, ~ SO3CF3, C].~, Br~, I , 8 Cl04 ) is contacted with ~he Li2S in the organ~ solvent 9 to be used in the electroly~e, thus generating TiS2 (to be 0 used in the fabrication of the active cathode~ and as co-11 product LiY (Y = electrolyte anion) in the organic solventO
12 By so doing, both the cathodic material and the electrolyte -~
13 are simultaneously produced~ Any contamination of t~e pre-14 cipitate (TiS2 in the above discussion~ by the solution wi~
not hamper its function, but will enhance it since wetting.~: :
16 of the cathode by the electrolyte is desirable~
17 The invention can be represented by the following 18 equation for the TiCl4 system, but it must be recognized 19 that this disclosure is relevant for the other systems des-cribed as preparative of compounds of ~he formula ~ O
21 TiCl4 + 4 HY ~ Li2S ~ TiS2 ~ ~LiY/organic ~ HCl ~2 cathode electrolyte 23 (y = ~ PF6 24 ~3 BF4 ~3So3CF3~
26 Trea~men~ of the TiS2 to fabricate a cathoc~e and insertion 27 of an anode (such as Li) will yield a battery.

29 All of the prepar~tive work described was carried out either in a dry box or under a blanket of nitrogen~
31 Both the starting metal (~4) and ~5) compounds and the sul-32 ides and selenides thus afforded are sensitive to moisture l and oxygen, especially in finely powdered form as results 2 from the heterogeneous precipitation method described, All 3 solvents were dried by standard techniques prior to use, 4 and anhydrous reagents were always employedO
EXAMPLE 1 - Preparation of TiS2 ~ZrS2, HfS2 and VS
6 The following e~ample employs as a starting mater-7 ial TiCl40 It was found that the procedure worked equally 8 well for ZrC14, HfCl~, MoC14 or VCl~o A solution of 10 9 millimoles of TiC14 (109 g) in ~et~ahydrouran (75 ml) was made up ln a dry box (TiC14 is not s~able in air or moisture)0 11 To this stirred soluti.on at room temperature wa~ added 0096g 12 (20 millimoles) of lithi~m sulfideO The yellowish solution 13 immediately began to darkPnO The reaet~on was allowed-to . .
4 proceed several hours a~though it was essential1y complete within one hour~ The resulting dark brown solid was fi:l-6 tered and washed wi~h 10 ml THF~ From the comb:ined fil-17 trates 83% of calculated ideal yield of lithium chloride was l8 isolated after evaporation of the ~olventO An elemental 19 analysis of the dark bro~ powder remaining ater drying rev aled 1~ to be TiS~ containing one~hal mole of solvent 21 ~etrahydrofuran and less than 5% by weight LiClo T~e analy-22 sis of other compounds prepared is listed belowO
.

cn c~l - ~o Q~
~ cr S.
:~~ o s~

~7o o o o ~ ~

`~ u~ :
~,o o . ~d :
~ . o e~
o u~ ; e~ .
p r f~ ~ ~
:: ~ ~ :
o ~ I~ ~

v ~4 : ~ ~ ~:

~-~:
c~
u~ -c~ ~
o ~l o ~ ~ :
0 ~ ~
P
~ ~ 4 a; . ~ ~ :
C~

.

~ 4~ ~

1 The solvent could bé removed by warming and pump-2 ing~ This prodwct waæ found to absorb a mole-equivalent of 3 ~m~nia in abou~ five minu~es (as opposed to days or weeks 4 for TiS2 prepared by conven~ional means3~ No x-ray difrac S ti~n pattern was seen for ~he m~erial due to lts small 6 c~stal size (~ ). The found BET surface area was about 7 lO m~/g~ which csuld be raised to about lOO m2/gm by treat-~g with pyridine and filtering and pumping to remove py-9 r~dine. - }
lo O~her solvents which could be su~stitut~d for 11 tetrahydrofuran were ace~onitrilea propylene carbonate9 12 acetic acid, dimethylfonmEmide (DMF) or no solvent at all~!
13 (run in excess TiCl4) 9 ~he rea~tion being run neat, In DMF
14 and ~ ne carbon~ a d~rs~n resu~ m ~tion to solidO
When sodium sul~ide was subst~tuted for lithium 16 sul~ide3 the reaction required much more t~me at ro~m temp- -17 erature and the removal of the side product9 sodl~m chloride .. . ~ .
18 from the dark TlS2 was achieved by washing wit~ 12~/o acetic 19 acid. Alternatively, ~he Qulf~de source could be ~mmonium sulfide (prepared in situ by first addlng e~cess amm~nia to 21 a te~rahydrofuran solu~ion of TiCl~ and subsPquen~ly bubbling 22 ln hydrogen sulfide), The side produc-t in this latter case~
23 ammonium chloride - could be removed by subllma~ion at 150C
24 (O,l torr)~
If one wishes to enhance the rrystallinity of the 26 product, the dry powder can be partially annealed by heating 27 several days at a temperature of 400C. or less in an inert 28 atmosphere. By this process, a product exhibiting the x-ray diffraction pattern typical of TiS2 was obtained.
~ Ye~ ano~her means of enhanclng the crystallinity ~, 31 of the produc~ is to employ a Soxhlet apparatu~ w~ereby the 32 Li2S i~ placed in a thimble over a refluxing ~olution ofr~

TiC14 in tetrahydrofuran. Platelets of TiS2 thus result after several days in the lower solution.
Additional corroboration of the products is found in their (mull) infrared spectra. Thus, for instance ~iS2 as obtained by the procedure described is essentially identical to that seen for a sample of TiS2 as obtained from Alfa Inor-ganics. The latter shows a broad band centered at 400 cm l , due to the Ti-S bond. The product of TiC14 and Li2S has a less broad band at 375 cm l (the breadth is diminished by smaller crystal size)~ ' -EXAMPLE 2 - Preparation of TiS2 (Zr2, HFS2 and VS2) , '' . The following example employs as a starting material TiCl4. It was found that the procedure worked equally well for ZrCl4, HFCl4 or VCl4. 300 ml of 0.2 M TiC14 in acetonit rile was slowly adde~ (dropjsec) to a refluxing solution o~
0.6 M Li2S in acetonitrile. The solution was cooled, filtered and was-hed with methanol to remove the LiCl formed. This was then followed by an ether wash and the product dried on a Bucher ~unnel in a dry box. The resulting product was gold-brown and gave an x-ray pattern of TiS2 with no further treat-ment.
EXAMPLE 3 - Preparation of NbS2 1TaS

.
This procedure is applicable to those transition metals of Group Vb which form pentahalides (Nb and Ta~ and the example is given for niobium pentachloride:
To a solution of lO millimoles of NbCl5 (2.68 g) in 50 ml tetrahydrofuran was added 1.15 g lithium sulfide (25 millimole~) and the reaction stirred in the dry box overnight.

The dark product obtained on filtration was shown to contain 60~ by weight NbSl 97.

E'XAMPLE 4'- Pr'eparation of Molyb'd'enum''Disul'flde Addition of lO millimoles of molybdenum tetra-- 14 ~

chloride and 20 millimoles of lithium sulfide to 30 ml THF with stirring results in a fine black solid which on filtration and drying contains 70% by weight MoS2. Most of the additional weight (60%) can be attributed to solvent which can be removed by heating to ca 150 C and pumping (1 torr).
EX~MPLE 5 - Stable ~omogeneous Dispersions . ~
If the reactions TiC14 + ~2S herein described are carried out in appropriate media, stable homogeneous dispersions of TiS2 in the liquid result (either accompanied by or in the absence of the precipitated solid). For instance, if propylene carbonate (PC) is used as solvent, the supernatant phase will be a dark brown opaque dispersion which is unchanged on filtra-tion (medium frit funnel) and which does not settle out over a period of weeks or months. Al-ternati~ely, if in addition to a nondispersing solvent (such as TH~) a dispersing agent such as ~
pyridine (or alkylamines~ is initially present, a similar dis- -persion will result. Murphy and Hull (J. Chem. Phys. 62 973 (1975)) have described dispersions of TaS2 in aqueous media which are considerably less stable due to e~entual decomposition of the sulfide b~ water (hydrolysis). In nonaqueous solutions such as those described in the instant invention such decomposi-tion does not occur and stàbility remains for months.
The reaction of a solution of TiClg in excessive tri-hex~lamine and tetrahydro~uran with hydrogen sul~ide provides another example of a means of dispersing the product TiS2 in the media. The presence of the amine in the reaction milieu seryes to disperse the extremel~ fine particles of the product. The dichalcogenides formed in quch dispersions may be adsorbed on hi~h surface area carbons, refractory oxides and high sur~acearea basic or acidic s~lids such as CaO, MgO, A12O3 silica-alumina, the ~' solution clearing with time.
EXAMPLE 6 - Metal-Rich Products for V and Nb Attempts to prepare stoichiometric disulfides of vana-dium and niobium via high temperatures (~ 400 C) techniques re-sult in metal rich products due to the vapor pressure of sulfur at elevated temperatures. By using the ambient temperature method described in this invention, essentially stoichiometric 2:1 sulfur to metal products result. Evidence (besides verify-ing analysis) is found in the behavior of our products on heat-ing to 100 C. In this situation sulfur is evolved and canclearly be visually perceived on the cooler parts of the tubes.

EXAMPLE 7.-..Op.en Circuit Vo~l.tage. o.f.TiS2 Elect.rode - !~
1 gram of TiS2 prepared in THF by the instant process ¦ .
was pressed into an aluminum grid to make a cathode. The open circuit voltage of this cathode was measured against Li in a LiC104/THF/~ME electrolyte and gave a value of 2.55 v and dis-charged to give 1,80 v and could be r:echarged. These voltages correspond to TiS2 (2.55 v) and LiTiS2 ~1,80 v) further proof of the TiS2 ~omposition.

.E~M~LE.~8.~-.T.is ..G.e.l..and.Gl.ass F.ormation To 40 mmol trihexylamine in 25 ml tetrahydrofuran, 10mmol TiCl4 was added. Then anhydrous hydrogen sulfide was .
sparqed into the solution at a flow rate of about 1-5 cc/sec for five minutes. In the course of ~his addition, the solution .
became dark and somewhat more viscous. After the addition, the dark mixture was allowed to sit at room temperature overnight, resultin~ in a black gel which, if pumped and heated to greater than 300C yielded a black glassy solid having no x-ray powder diffraction pattern. Scanning electron microscopy (SEM) veri-fied that the product was a glassy phase, and x~ray Eluorescence an~lysls showed ~ 16 -1 titanium and sulfurO
2 b2~YL~ YYY~:_Des~
3 The transition metal dichalcogenides are known 4 to absorb ammonia to form l.l products ~U.S. Patent 3,766,064, F.R. Gamble, R~Ao KlPmm and E. F. Ullm~n). The 6 rate of this reaction depends on the surface area of the 7 solid dichalcogenide (if ammonia vapor at ambient conditions 8 is used). For instance~ lO0 mesh TiS2 requires several 9 days to react completely with ammon~a. The TiS2 prepared by the method outlined in Example l~ when contacted--with-11 a~monia vapor under ambient conditions in a gas bure~,ab-12 sorbed one mole within five minutes tno more was picked 3 up)-4 EXAMPLE lO - Reaction with n-Buty~
A general reaction of the Group IVb and Vb trans-16 ition metal dichalcogenides is the formation of adducts 17 of lithium using n-but~llithium. The disulfide products 18 of the reactions described herein reacted rapidly with 19 n-butyllithium to form~such adducts:
Reaction Product LJ Iro~ h~Q~ 5~LL~2Y~
.

21 TiS2 l.09 22 ~S2 1~48 23 EXAMPLE ll - Use of VS2 ~as produced) in a Li Bat~ery 24 as Cathode VS2 is not known as a stoichiometric compound 26 and has not been prepared by methods of the prior art. Such 27 material prepared by the instant process, however, was 28 reacted with ~ -butyllithium to give a composition LiXVS2 29 (0~ X ~ l.5). The starting material has a 2.1 sulfur/
vanadium ratio. The starting VS2 has an open circuit vol-31 tage of about 2.45 volts and the lithiated material has an 32 open circuit voltage of l.80 volts against lithium. The - 17 ~

reactlon of n-butyllithium (Whittingham & DinesJ~t~ R:e84 2 Bu~ 0~8~ 97~ d the fa~or~b~;e c~'a~ged/di~`éY~arged vol~-3 age- make ~S~JL~S.2 ~l ~tr~c~ive cathode m~terialc 4 Vanadium sulf ide oompounds prepared in ~che pas t and characteriæed as beiIIg VS2 were all prepared via high b tempera~ure ~:echniques5, iOe~ o~er 400C.
7 Experiments oonduc~ed in the course of developing B the instan~ process h~ve indic~ed t~a~ hig~ tempera~ure prepara~i~n o:f vanadlum sul fides yield compounds of ~he ~o formula VsS8~ V2~3D e~c- ~nd not VS2-11 Van~di~m sulf~de compositions whic~ are no~ VS2 ~2 have been fc3~nd ~o reac~ wi~ch n-bu~ylli~hium only t~o 13 exten~ of 0u2 M maximum~
~4 Such material~ ean;not be uti~ized as 'battery ~
15 cathodes since ~he min~sc~lle lilthi~n ~ake-up drama~c~cally ~ afec~s vol 1~ag~ conside~aticn ~nd charge-dis~arg~ abillties O
17 Vanadium sulfides prepared by ~e proces~ of ~e 18 in~tan~ inven~i~sn, h:D~3ver9 are of 'ch~ ~o~n~a VS2 and take 19 up 1~, 5e ~i~n upon a~ ure with n-butyllithiums Such 20 behavior3 whlch is-simllar ~eo that of Ti~2 lndicates that 21 bo~h ~ruc~urally arld stoichiorn~3~crically Ti52 and VS2 pre-22 pared by l~e instant process are similarJ indeed" th~ VS2 23 as such can be prepared. Supposed compounds of VS2 prepared 24 by prior ar~ high ~emperature techniques di~fered marke~ly from TiS2 (and ~rom the VS2 as now prepared)7 s~rong evi-26 dence ~ha~ the compounds of the prior art are not truly VS
27 EXAMPLE 12 - Use as a Catalys~
28 NbS2 prepared by this me~hod is a more activa ~ catalyst for ~he hydrodesulfurization of dlbenzo~hiophene at the same ~emperature (400~) and pressure (4~0 psi) ~han 31 NbS2 prepared from the elements via prior art techniques.
32 Thus, layered c~mpounds prepared ln this manner are more . - ~8 _ 2~

active than any previously prepared compounds.
~ate Constants NbS2 - prepared from elements K = 8.7 x 10 7 gm 1 sec 1 NbS2 - prepared as above K = 13 x 10 7 gm 1 sec 1 TiS2 in Group IVb is more active prepared in the instant manner than by bulk methods. Also', VS2 in Group Vb was active as a catalyst. VS2 cannot be prepared in bulk by previously known methods as stated above.
EXA~LE:1;3 -~ Formation 'of an Intercalation Complex Directly Ordinarily,'using large crystal size transition metal dichalcogenides prepared by other means, sterically restricted amines such as 4-t-butylpyridine cannot intercalate between the layers and form inclusion compounds (Gamble et al, Science Vol.
174, pg 493, 1971). However, if during the precipitation re-actions described herein, such molecules are present, they will be included in the solid product which forms in situ. As an example, if 5 mmol of 4'-t-botylpyridine is present in the THF
solution when 10 mmol of TiS2 is prepared via TiC14 and Li2S, the product, a dry dark solid powder, will contain the amine.
EXAMPLE 14 - Preparation of US2 under Ambient Conditions (in Dryb~x~ ' . . _ .
A green solution was made up co'ntaining 3.70 g of UC14 (10 mmoles) in 100 ml THF. To this solution was added 0.92 g (20 mmoles) Li2S with stirring. The color darkened to brown and the reaction was stirred a day at room temperature. On fil-tering, washing with 20 ml THF and drying of the precipitate 3.07 g black powder (102~ yield) resulted. ~n x~ray diffrac- ¦
tion of this product showed no reflections due to the fine particle size.
~n "Handbook of Preparative Inorganic Chemistry" V. 2 (second edition) edited by G. Brauer (Academic Press, ~( - 19 ~ ,j, 1 1965) on page 1446 is de~ailed ~he ~ypical preparation of 2 US2 (from UC14 + H2S~ a~ 600-700~.
3 ~
4 Into 50 ml acetoni~rile; ~0 millimole~ zirconium tetrachloride is added and ~hen9 with stirring 20 mill~moles ~ o f li~hium selenide is added por~ionw~se, After allowing 7 to s~ir several hours, ~he solld produc~ is collec~ed on 8 a filter and w~hed wi~h acetoni~rile and dried, Thus, 10 9 millimol~s of zirconlum dl~e-enide i~ afforded.
10 ~
11 Polys~lfide m~y be prepared by adding ~he proper 12 stoichicme~ric æmount ~ ~u~rw~he Ll2S9 as in the pre-13 vious ex~mple~9 to yield the. appropria~e Li2$n ~or the de-14 sired reaction~ Tw~ examples of ~he preparation of known 15 polysul~ides are sho~ b~lowo ~ ~i 16 VCl~ ~ 2Li2$~ - > V5 ~ ~ 4LiCl 17 TiC14 ~ Li~S~ + Li2S -~ T~S3 ~+ 4LiCl - l8 However~ ~his me~hod is no~ l~mi~d to known polysulfides 19 but is a route o previous~y unknown polysulfides such as TiS49 TaS6 etcO I~s me~hod also yields dispersions9 gels, : ~1 etc. of these materials whose properties will not be gov-22 erned by the chaln~like morphology of ~he polysulfid~s.
23 EXAMPLE 17 - Neat F~ep æ a~ion of C~ys~alline TiS2 from _ NH39~æS and TiCl~ :
Into a ~hree-n~cked flask~ a quantity of (approxi-26 mately 5 grams) of (NH4)HS or (NH~)2S wa~ prepared by flow-27 ing in NH3 gas and H2S ga5, To ~he resulting white solid 28 3.8 gms of TiC14 (20 mmol) was added dropw-ise. A re~ction 29 immedia~ely occurred yielding a black^brcwn solid~ which was TiS2 ~ (NH~)Cl. ~hi5 black brown solid was remo~ed ~rom 31 the flask and sealed in vacu~n in a 20 mm diæmeter quartz 32 tube which was 2S inO longO T~e ~ube was placed in a - 20 _ , .

~empara~ure gradient wi~h one end a~ 380C and the o~her -:
2 at 100 C O for on2 day . (NH~ ) Cl sublimed and condensed at 3 ~he oolder end ~hus effeeting separation7 At the hot end, 4 ~che TiS2 annealed yielding a perfec~ crys~alline x-ray S powder pa~ctern~

- 2~ -, .. ... ..... --

Claims (14)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for the preparation of chalcogenides of the formula MXy wherein M is a metal selected from the group consisting of IVb, Vb, moly-bdenum and tungsten transition metals of the Periodic Table of Elements, X is selected from the group consisting of sulfur, selenium and tellurium, and y is a number ranging from about 2 to about 4, which comprises reacting neat a transition metal salt, the transition metal being selected from the group con-sisting of Group IVb, Vb, molybdenum and tungsten, with a source of sulfur, selenium or tellurium, said source having a formula selected from AHX wherein A is an alkali metal or NH4+ and X is sulfur, selenium or tellurium, and A2X wherein A is an alkali metal, NH?, RNH? , RR'NH? or RR'RR"NH+ wherein R, R' and R" are the same or different, and are of the group C1-20 alkyl or C6-20 aryl, and X is sulfur, selenium or tellurium, at a temperature of from 0 to 400°C.

2. The method of claim 1, wherein the anion of the salt is sel-ected from the group comprising halide, acetate, carboxylate, perfluorocar-boxylate, acetylacetonates and hexafluoroacetylacetonates, wherein the carbonaceous moiety of the anion is a C1 to C8 hydrocarbon or fluorocarbon.

3. The method of claim 1, further characterized by the step of contacting the isolated product with an intercalating solvent, thereby form-ing an intercalate chalcogenide, then driving the solvent off by means of heat, thereby generating a chalcogenide of increased surface area.

4. The method of claim 3, wherein the intercalating solvent is selected from the group consisting of pyridine, ammonia, C1-C20 amines, alde-hydes, ketones, amides, heterocyclic bases and amidines, and the solvent is subsequently driven off at a temperature of between 75-200°C.

5. The method of claim 1, wherein the product is a stoichiometric chalcogenide.

6. The method of claim l, further characterized by the presence of a non-aqueous solvent in the reaction.

7. The method of claim 6, wherein the non-aqueous solvent is selected from the group consisting of acetonitrile, benzonitrile, propionitrile, acetone, C1-C20 alkyl halides, C6-C20 arylhalides, 1,2-dimethoxyethane, diglyme, N-methylformamide, dimethylformamide, aromatics of C6-C20 carbons, pyridine, sulfolane, tributyl phosphate, C5 to C12 alkanes, C4-C8 ethers and esters, anhydrous acids, dimethyl sulfite, and C1 to C20 amines.

8. The method of claim 7, wherein the anhydrous acids are formic acid and glacial acetic.

9. The method of claim 1, wherein the temperature of reaction is between 25-300°C.

10. The method of claim 1, wherein the source of sulfur, selenium or tellurium is selected from the group consisting of Li2S, alkali metal and ammonium hydrosulfides, (NH4) 2S, Na2S, Li2Se, Li2Te, (NH4) 2Se, (RNH3) 2S, (RR'NH2) 2S, (RR'R"NH) 2S wherein R, R' and R" are the same or different, and are selected from the group consisting of C1 to C20 alkyl and C6-C20 aryl group.

11. The method of claim 1, further characterized by the step of annealing the isolated product at a temperature of over about 450°C, thereby generating a product having low surface area, moderate particle size and high crystallinity.

12. The method of claim 1, which comprises generating di- or poly-chalcogenides in the presence of intercalating agents, wherein said inter-calating agent is initially present in the reaction mixture as a solvent.

13. A method for the simultaneous production of a cathode of the formula MXy wherein M is a transition metal selected from the group consisting of Group IVb, Vb, molybdenum and tungsten, X is selected from the group consis-ting of sulfur, selenium and tellurium and y is a number from about 2 to about 4, and electrolytes,which comprises:

(a) mixing a transition metal salt wherein the transition metal is selected from the group consisting of Group IVb, Vb, molybdenum and tungsten and the anion of the salt is selected from the group consisting of halide, acetate, carboxylate, perfluorocarboxylate, acetylacetonate and hexafluoro-acetylacetonate wherein the carbonaceous moiety of the anion is a C1 to C8 hydrocarbon or fluorocarbon, with a non-aqueous solvent;
(b) mixing the solution of step (a) with a strong acid HY wherein Y is selected from the group consisting of C1-, Br-, I-, C104-, PF6-, BF4-, and S03CF3-;
(c) mixing the solution of step (b) with a lithium salt of sulfide, selenide or telluride at a temperature of from 0 to 400°C, thereby generating the MXy cathode and the electrolyte LiY.

14. The method of claim 6 wherein the solvent is selected from the group consisting of propylene carbonate, dimethylformamide, pyridine, acetonitrile, benzonitrile, propionitrile, 1,2-dimethoxyethane, diglyme and N-methylformamide.