CROSS-REFERENCE TO RELATED APPLICATION The present application claims priority to co-owned U.S. Provisional Application Serial No. 60/058.675 filed on 12 September 1997, the entire contents of which is hereby incorporated by reference.

FIELD OF THE INVENTION The present invention relates to the low temperature and particularly room temperature synthesis of lanthanide chalcogenides, such as lanthanide sulfides and the doping of lanthanide ions into chalcogenide matrices, such as sulfur based matrices. More specifically, lanthanide chalcogenolates are useful synthetic reagents that react with elemental chalcogen or materials with chalcogen-chalcogenbonds to form lanthanide chalcogenide compounds at room temperature. By controlling the reaction conditions, crystalline lanthanide chalcogenide clusters can be isolated in crystalline form.

BACKGROUND OF THE INVENTION The utility of lanthanide ions doped into sulfide-based matrices is well documented, primarily as well defined photon emitters in flat panel display materials, and as amplifiers in fiber optic materials. The useful properties of the lanthanides originate with their unique electronic structure: because the valence f-orbitals are essentially uninvolved in bonding with the ligands that constitute the metal coordination sphere electronic transitions associated with these f-electrons are virtually independent of ligand identity, temperature and pressure. As

such, the absorption or emission of lanthanides doped into a solid state matrix can be used in materials that may be subjected to varying pressure, temperature, or composition. with little or no change in the absorption or emission energy. Lanthanide sulfides are also under investigation as possible pigments.

There are a number of approaches to the synthesis of lanthanide doped chalcogenide materials. Because of the extreme air sensitivity of lanthanide metals and the extremely high temperatures needed to induce metal vaporization, vapor phase epitaxy (VPE) and liquid phase epitaxy (LPE) are generally not useful synthetic approaches to making these doped materials.

The use of molecular lanthanide sources has received considerable attention.

Organometallic chemical vapor deposition (OMCVD) using lanthanide silylamides or lanthanide alkyls can be used in the CVD synthesis of lanthanide doped sulfides, but the procedure requires highly toxic H2S codoping sources. Lanthanide halides (MX3, where M is a lanthanide and X is a halide such as Cl, Br, I) can be used, but the deposited lanthanide tends to form MX clusters and thus interact negligibly with the chalcogenide based matrix.

Volatile lanthanide carboxylates can also be employed, but again, after the high temperature decomposition required to remove the organic residues, the lanthanide ions tend to associate as lanthanide oxide clusters that do not interact strongly with the chalcogenide matrix. It is preferable to have a lanthanide source that does not contain such strongly binding ligands, so that the lanthanide ion binds preferentiallyto the chalcogenidematrix, i.e. the sulfide matrix.

An approach to alleviating these disadvantages involves the use of lanthanide precursors in which the anionic ligands coordinated to the metal do not stabilize the metal as well as the chalcogenide, i.e. sulfide does, such that when exposed to the chalcogenide matrices. the ligands will be displaced. Ideally, the displaced ligands would sublime or distill at or near room temperature.

Some general reports of the utility of lanthanide doped chalcogenide glasses or semiconductors, and the doping of lanthanide ions into these chalcogen matrices include, for example:

P.K. Kumta and S.H. Risbud. J. iWat Sci. 29, 1135 (1994). Rare-earth chalcogenides- an emerging class of optical materials.

P.K. Kumta and S.H. Risbud. Progress in Crystal Growth and Characteri-alion 22, 321 (1991). Chemical processing of rare earth chalcogenides.

J. Nishii et al., J. Non-Cryst. Solids, 95/96, 641-6 (1987). Transmission Loss of Ge- Se-Te and Ge-Se-Te-Tl Glass Fibers J. Nishii et al., J. Non-Cryst. Solids, 140, 199-208 (1992). Recent Advances and Trends in Chalcogenide Glass Fiber Technology: a Review J.S. Sanghara et al., J. Appl. Phys., 75, 4885-91 (1994). Effects of Scattering Centers on the Optical Loss of As,S3 glass fibers in the infrared.

T. Katsugama and H. Matsumura, J. Appl. Phys., 75, 2743-8 (1994). Light Transmission characteristics of Te based chalcogenide glass for Infrared Fiber Application.

G.S. Pomrenke et al., Rare Earth Doped Semiconductors (MRS Symposium V. 301): Materials Research Society; Pittsburg, PA, 1993.

K. Swiatek, et al., J. Appl. Phys., 74, 3442-6 (1993). Optical Recombination Mechanisms in Eu.(II) doped CaS and SrS thin films Y. Charreire, et al., Program and Abstracts of the ICFE-2, Aug. 1-6, 1994. University of Helsinki. Helsinki, Finland, J. Kansikas and M. Leslela, eds. p. 326.

Y. Charreire et al., J. Electrochem. Soc., 139, 619 (1992). EXAFS Study of Tb activated ZnS Thin Films Y. Charreire et al., J. Electrochem. Soc. 140, 2015 (1993). EXAFS of Luminescent Centers in II-VI Thin Films K. Karpinskaet al., J. Alloys and Compounds 225, 544 (1995). Optical Properties of CaS:Tb grown by atomic layer epitaxy.

C.R. Ronda, J. Alloys and Compounds 225, 534 (1995). Phosphors for lamps and displays: an applicational view.

M. Pham-Thi, J. Alloys and Compounds 225, 547 (1995). Rare earth calcium sulfide phosphors for cathode ray tube displays.

G. Harkonen, et al.. J. Alloys and Compounds 225, 552 (1995). Multicolor thin film electroluminescent displays: a new application of rare earths.

General reports describing the synthesis and physical properties of lanthanide

chalcogenolates include: J. Brennan et al., J. Amer. Chem. Soc. 115, 8501 (1993). "One Dimensional Coordination Polymers: [ (py)2Eu(SeC6H5)2 } 4]n and [(THF)3Eu(SeC6H5)2]n" J. Brennanet al., J. Chem. Soc. Chem. Comm. 1537 (1993). "A Trivalent Rare Earth Complex of the Heavier Chalcogenolates: (py)4YbLi(SePh)4" J. Brennan et al., Inorg. Chem. 33, 2743 (1994). "Pyridine Complexes of the Divalent Ytterbium Chalcogenolates Yb(EC6H5)2, (E=S, Se, Te)." J. Brennan et al., J. Amer. Chem. Soc. 116, 7129 (1994). "Rare Earth Phenyl- Tellurolates: 1 D Coordination Polymers" J. Brennan et al., Inorg. Chem., 34, 3215 (1995). "Trivalent Lanthanide Chalcogenolates: Synthesis, Structure, and Thermolysis Chemistry" J. Arnold et al., J. Amer. Chem. Soc. 115, 2520 (1993). Preparation of lanthanide tellurolates and evidence for the formation of cluster intermediates in their thermal decomposition to bulk metal tellurides.

J. Arnold et al., J: Amer. Chem. Soc., 117, 3492 (1995). Trivalent Lanthanide Selenolates and Tellurolates Incorporating Sterically Hindered Ligands and Their Characterization by Multinuclear NMR Spectroscopy and X-ray Crystallography.

D. Cary and J. Arnold, Inorg Chem. 33, 1791 (1994). Synthesis and Characterization of Divalent Lanthanide Selenolates and Tellurolates, x-ray Crystal Structures of Yb[SeSi(SiMe3)3]2(TMEDA)2 and (Eu[TeSi(SiMe3)3]2(DMPE)2A2(muDMPE).

P.A. Bianconi et al., J. Am. Chem. Soc. 114, 3159 (1992). The Synthesis of Lanthanide(II) Arylchalcogenolates: Precursors to Magnetic Semiconductors.

P.A. Bianconi et al., Inorg. Chem. 33, 5188 (1994). Molecular Precursors to Lanthanide(II)- Based Semiconductors: Synthetic Pathways toward the Preparation of Lanthanide Monochalcogenide Precursors.

K. Mashima et al., J. Chem. Soc. Chem. Comm. 2523 (1994). "Formation of Lanthanoid(II) and Lanthanoid(III) Thiolate Complexes derived from Metals and Organic Disulfides: Crystal Structures of [(Ln(SAr)3(THF)3}2] (Ln=Sm, Ea.), [Sm(SAr)3(py)2(THF)], and [Yb(SAr)3(py)3" All of the references and patents referenced in this application are incorporated herein

by reference.

Thus, the references cited above indicate certain problems in the art. These problems include overly reactive precursors, toxicity of reagents, and poor interaction benveen the doped lanthanide ion and the chalcogenide source. Accordingly, it would be extremely useful to have the metals of interest in a single, stable molecule that would react with materials containing chalcogen-chalcogenbonds to incorporate the lanthanide ion into, and have it bond directly with, the chalcogenide matrix. The present invention provides the synthetic process to make such materials, as well as the resultant doped matrices which can be formed at low temperatures, tailored to have specific properties and are free from impurities.

The present invention improves on all known lanthanide doping sources by employing molecular lanthanide compounds in which the bonds to all the anionic ligands are less stabilizing than the chalcogenide-lanthanidebonds, so that materials with, for example, sulfur- sulfur bonds are reduced to sulfido ligands, and the lanthanide ion bonds directly to the sulfide matrix.

Accordingly, it is an object of the present invention to provide a single-source metalloorganic precursor. It is another object of the present invention to provide a metalloorganic precursor which is structurally simple so as to evolve stable organic by- products which do not react further to contaminate the final product. It is a further object of the present invention to provide a metalloorganic precursor capable of depositing the metals of interest in precise ratios. It is another object of the present invention to provide a metalloorganic precursor with a lower toxicity. It is a further object of the invention to increase the yields of novel lanthanide/chalcogenide clusters. These objects and other advantages will become apparent to the skilled artisan in view of the disclosure set forth herein.

SUMMARY OF THE INVENTION The present invention relates to a metal organic composition of the formula: (L)pM-(ER)n wherein

M is a lanthanide element, E is a chalcogen. L is nothing or a Lewis base ligand. R is an alkyl having 1-20 carbon atoms, an aryl, a substituted aryl, a silyl, an amido, or a phosphido, p is an integer from 0 - 10 and n is an integer from 2 - 3.

Another embodiment is a passivating composition for a metal organic composition.

This passivating composition is of the formula: LpM(2-S-NC5H4)2 wherein L is a Lewis base, M is a lanthanide metal and p is an integer from 0 - 6.

Another embodiment is chemically passivated metal organic composition. This composition includes (i) a metal organic composition of the formula: (L)pM-(ER)n, wherein M is a lanthanide element, E is a chalcogen, L is nothing or a Lewis base ligand, R is an alkyl having 1-20 carbon atoms, an aryl, a substituted aryl, a silyl, an amido, or a phosphido, p is an integer from 0 - 10 and n is an integer from 2 - 3; and (ii)a passivating composition of the formula: LpM(2-S-NC5H4)2 wherein L is a Lewis base, M is a lanthanide metal and p is an integer from 0 - 6.

Another embodiment is a process of incorporating a lanthanide into a chalcogenide matrix. The process includes the steps of(i) providing a chalcogenide matrix, (ii)further providing a lanthanide precursor having anionic chalcogenolate ligands, wherein these ligands are thermodynamicallyless stabilizing than a lanthanide/chalcogenidobond and (iii) allowing the precursor to react with the chalcogenide matrix to form one or more direct lanthanide- chalcogenide bonds.

Another embodiment is magnetic coating for a substrate. This coating is formed from a metal organic composition of the formula: (L)pM-(ER)n, wherein M is a lanthanide element, E is a chalcogen, L is nothing or a Lewis base ligand. R is an alkyl having 1-20 carbon atoms, aryl, substituted aryl, silyl, amido, or phosphido, p is an integer from 0 - 6 and n is an integer from 2 - 3.

Another embodiment is a lanthanide chalcogenide composition comprising the reaction product of (i) a lanthanide chalcogenate of the formula: (L)pM-(ER)n, wherein M is a lanthanide element, E is a chalcogen L is nothing or a Lewis base ligand. R is an alkyl having 1-20 carbon atoms, an aryl, a substituted aryl, a silyl, an amido or a phosphido, p is an integer from 0 - 6 and n is an integer from 2 - 3; and (ii) an elemental chalcogen or a material having chalcogen-chalcogen bonds.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 represents a composition according to the present invention having the molecular structure of Gd8S6(SPh),2(THF)8 (1), with the H atoms removed and the C and 0 atom labels omitted for clarity. The Gd-S2- bond lengths range from 2.746(4) to 2.835(4)Å and average 2.80Å, while the Gd-S(Ph) (labeled S') bond lengths range from 2.794(4) to 2.881(4)Å, and average 2.84Å. Thermal ellipsoids are shown at the 50% probability level.

The analogous Pr and Nd clusters are isostructural.

Figure 2 represents a composition according to the present invention having the molecular structure of Sm8Se6(SePh),2(THF)8 (1), with the C and H atoms removed and the O atom labels omitted for clarity. The Sm-Se2~ bond lengths range from 2.847(2) to 2.971 (2)A and average 2.93A, while the Sm-Se(Ph) (labeled Se') bond lengths range from 2.916(2) to 3.015(2)Å, and average 2.98A. Thermal ellipsoids are shown at the 50% probability level.

Figure 3 represents a composition according to the present invention having the molecular structure of the cation in [Sm,S7(SePh)6(DME)7]+[Hg3(SePh)7]~ (2), with the C and H atoms removed and the 0 atom labels omitted for clarity. The Sm-S bond lengths range from 2.66(2) to 2.93(2)Å (average 2.79Å), and the Sm-Se bond lengths range from 2.930(9) to 3.12(1)8, and average 3.03A. Thermal ellipsoids are shown at the 50% probability level.

DETAILED DESCRIPTION OF THE INVENTION As used herein, the term "alkyl" includes, but is not limited to all alkyl groups usually having 1 to 20 carbon atoms. Alkyl is also intended to include methyl to octyl straight chain and branched groups, and 4, 5 or 6 member hydrocarbon rings.

The term "aryl" as used herein includes, but is not limited to. phenyl, naphthylene, anthracene. phenathrene groups and the like. Aryl also includes groups such as -C-(phenyl)3, -C(4-methylphenyl)3, -C(4-methoxyphenyl)3, and the like. Aryl also includes alkyl C,20 and heterocyclic aryl groups such as pyridine, pyrrole, quinoline, furan, and the like.

Hydrocarbons such as phenyl are preferred.

As used herein, the phrase "substituted aryl" includes an alkyl CI-20 having halogen substituted for one or more protons on the aryl ring. Generally 1, 2 or 3 proton substitutions are preferred. Substituted aryl also includes substituted heterocyclic aryl groups.

As used herein, the term "silyl" includes -SiR1R2R3 groups, where Rj (i=l, 2 or 3) are alkyl, aryl, halo, substituted aryl, N-heterocyclic aryl, or substituted N-heterocyclic aryl.

The phrase "Lewis base" as used herein is intended to include all molecules or compounds which donate one or more electron pairs. Non-limiting examples of Lewis bases useful in the present invention, include for example tetrahydrofuran (THF), pyridine, acetonitrile, dimethoxyethane (DME), amines such as tertiary amines, phosphenes such as tertiary phosphenes and the like.

In the present invention, metalloorganic compounds are readily prepared by reduction of REER (R and E being defined above) with elemental lanthanide in weak donor solvents.

Because these compounds contain readily displaced ligands that are inferior to, for example S2-, they are readily displaced from lanthanide coordination spheres, and evolve volatile REER in the process. These properties are in stark contrast with those metalloorganic compounds of the prior art, which rely on compounds containing highly electronegative halide-. oxygen-, nitrogen-, or carbon-based anions that are not displaced by sulfide.

In one embodiment, the present invention relates to metalloorganic compounds having the formula LpM8E6(ER),2, wherein L is a Lewis base; p ranges from 0-8; M is a lanthanide metal: E is a chalcogen; and R is hydrogen or a substituted or unsubstituted hydrocarbon and may contain a hetero atom; R can also be AR', or BR'3 wherein A is N, P, As or Sb and B is Si, Ge, Sn or Pb, and R' is hydrogen or a substituted or unsubstituted hydrocarbon and may contain a hetero atom. E is a group VI element including for example, S, Se and Te. R and R' are desirably selected from the group consisting of alkyl, aryl, alkyaryl or aryalkyl, each having C, 0. More desirably, R is phenyl and/or R' is methyl. These metalloorganic compounds represent novel lanthanide clusters which can be deposited on a substrate as a coating having magnetic properties. Such properties can be uniform and well defined due to the unique structure of the cluster and the electronic structure of the lanthanide elements.

Ordered arrays of such clusters may have wide applications, including use as magnetic media. When the element Gd is used to form the cluster, the cluster has 56 impaired electrons, the largest number of unpaired electrons found in a discrete lanthanide molecule.

The metalloorganiccompounds of the present invention can be capped, i.e. chemically passivated, with -(-2-S-NC5H4)2. The capping agent serves as a protective group to enhance the air stability of the metal. The capping agent used is a novel compound in itself, which also performs as a reducing agent for organic synthesis. The capping or reducing agent has the formula LM(2-S-NC5H4)2 wherein L is a Lewis base; p is an integer from 0-6; and M is Sm or Yb. More desirably, L is tetrahydrofuran (THF), dimethoxyethane (DEM), pyridine and combinations thereof. The reducing agent may be in crystalline form, amorphous form or in organic solution.

A further embodiment of the present invention includes a lanthanide doped chalcogenide matrix which is substantially free of optically absorbing or scattering impurities and is formed by the steps of: (i) providing a lanthanide precursor having anionic chalcogenolate ligands which are thermodynamically less stabilizing than a lanthanide/chalcogenidobond; and (ii) allowing this precursor to react with the chalcogenide matrix to form one or more direct lanthanide-chalcogenide bonds. The lanthanide precursor has the formula LpM(ER)n, wherein L is a Lewis base; p ranges from 0-10; M is a lanthanide

metal: E is a chalcogen. and R is hydrogen or a substituted or unsubstituted hydrocarbon and such hydrocarbon can contain a hetero atom; R can also be AR'2 or BR'2 where A is N, P, As or Sb: B is Si. Ge, Sn or Pb; and R' is hydrogen or a substituted or unsubstitutedhydrocarbon which can also contain a hetero atom. Desirably R and R' are hydrocarbons having C,20.

Desirably, in the lanthanide doped matrix (E) is includes S, Se, Te and combinations thereof and Rand R' are independently an alkyl, aryl, arylalkyl or alkaryl group, each having C,.20, such as phenyl. In preferred matrices, E is S or Se, R is phenyl and M is Tm. Tb, Er or Eu.

In a further embodiment of the present invention there is provided a chalcogenide matrix which is observably free of impurities which are optically absorbing or optically scattering. This matrix includes one or more lanthanide atoms directly bonded to a chalcogenide within the matrix. The inventive matrices do not suffer from the by-product impurities of the prior art techniques of forming lanthanide/chalcogen matrices.

Chalcogenide matrices useful in the present invention include, without limitation, amorphous main group chalcogenides, crystalline metal chalcogenides and the like. For example. these include crystalline materials such as ZnS and CaS, as well as other materials formed from Group II, Group XII and Group XIII metals as set forth in the Periodic Table of the Elements. Combination of matrices, such as composite or layered structures are contemplated.

The amount of lanthanide dopant present in the chalcogenide matrix may vary and will depend on the specific end-use. Although conventional dopant quantities in matrices range from about 0.001 to about 5 molar percent, the matrices of the present invention provide for greater variation in quantity of dopant present and contemplate use of molar percents in the range of about 0.001 to about 50% or more. For applications directed to emission of photons, about 0.001 to about 5 molar percent of the dopant are desired.

The ability of the present inventive lanthanide doped chalcogenideto be formed at low temperatures, e.g. from -70°C to about 400"C, and desirably in the range of about room

temperature to about 70"C. has many advantages over the art. High temperature exposure is not necessary to destroy or attempt to destroy impurities common to the prior art because the inventive matrices are formed substantially free of impurities which affect the utility of the matrices. For example certain glass matrices cannot be heated above 400"C to remove impurities without causing them to crystallize, thereby rendering them virtually useless as a fiber optic material. Moreover, the ability of the inventive matrices to be formed at low temperatures also contributes to their ability to contain relatively high dopant concentrations.

In semi-conductor applications, high temperatures can be deleterious to the quality and integrity of the individual layers and the desired demarcation of specific layers, which in turn decreases the overall quality of the semi-conductor. The present matrices do not suffer from such problems.

To prepare lanthanide doped semiconductor films, any of the precursor materials set forth above are deposited onto substrates such as ZnS or CaS in the following manner. A quartz tube containing the precursor compound and a slice or wafer of the substrate material is placed inside a resistively heated tube furnace having a temperature gradient ranging from 100"C to 6000C along the length of the apparatus. The compound is placed at the cooler end of the tube while a stream of inert gas such as nitrogen or argon gas is passed through the tube over the compound and toward the substrate. On impinging the hot substrate, the precursor compound reacts with the sulfur rich substrate surface depositing a thin film of lanthanide atoms thereon. Any volatile decomposition products are removed in the gas stream.

Alternatively, the above process can be carried out under high vacuum, such as for example at 1 OF2 to 10.6 Torr, using the vapor pressure of the gaseous compound to transport the material to the substrate. In this case, the decomposition products condense in a part of the tube held at a much lower temperature (15-45 "C).

The following examples are set forth to illustrate the synthesis of the compositions of the present invention. These examples are provided for purposes of illustration only and are not intended to be limiting in any sense.

EXAMPLE 1 Reaction of Ln(SeR)3 with S to give materials with M-S2- bonds: Synthesis of i(DME)7 Sm7S7(SePh)6j+[Hg3(SePh), The following example shows that lanthanide selenolates are reactive with sulfur.

The chemical agents, reagents and solvents used in the present Examples are obtained from U.S. chemical supply plants, including for example, Aldrich Chemical Co. All syntheses were carried out under ultrapure nitrogen (JWS), using conventional drybox or Schlenk techniques. Melting points were taken in sealed capillaries, and are uncorrected. IR spectra were taken by diffuse reflectance in KBr using a Perkin Elmer 1 720X FTIR at 4 cm-' resolution from 4000-450cm-'. NMR spectra were recorded on a Varian XL 200 MHZ NMR 24.5"C. Elemental analysis were preformed by Quantitative Technologies, Inc. (Salem, NJ).

Clusters of lanthanide sulfides are formed from the reaction as follows: PhSeSePh (0.94 g. 3.0 mmol) was added to a Schlenk tube containing Sm (0.30 g, 2.0 mmol), Hg (0.15 g, 0.75 mmol) and dimethoxyethane (DME) (50 mL). After one day at room temperature, a yellow precipitate had formed. After 2 days at room temperature, S was added (48 mg, 1.5 mmol) and the precipitate dissolved within 30 minutes. The reaction was stirred for 1 more day at room temperature after which the yellow solution was filtered, concentrated to about 25 mL and layered with hexane (25 mL) to give pale yellow crystals of [(DME)7Sm7S7(SePh)6]+[Hg3(SePh)7]~ (75 mg. 8%)] The compound did not melt but turned golden around 2400C and continued to darken with increasing temperature.

The analytical calculation for the elemental analysis was as follows: Cl ,0H,45O,6HE3S7Se,3Sm7: C, 28.0; H, 3.00. Found: C, 26.8; H, 3.05. The compound does not show an optical absorptionmaximum from 300 to 800 nm in tetrahydrofuran(THF) indicating it is colorless. IR(Nujol): 2929 (s), 1571 (m), 1461 (s). 1378 (s), 1261 (w), 1190 (w), 1113 (w), 1095 (w), 1044 (w), 857 (s), 823 (w), 807 (w), 732 (s), 690 (s). 664 (m), 464 (s) cam~'.

NMR (NC5D5, 200C): 7.95 (14 H), 7.05 (21 H), 3.48 (32 H), 3.25 (48 H). The Sm-SePh resonances were not observed, indicating the SePh is coordinated to more than one Sm atom.

Unit cell data (-120"C): orthorhombic space group Pbca, with a = 26.099(7)Å, b = 22.440(7)A. c = 20.002(5)Å, v = 11714(6)Å3.

EXAMPLE 2 Reaction of Ln(SR!3 with S to give materials with Ln-S2 bonds Synthesis of (THF)8-nS8 (6SPh)12 was under taken as follows: Under nitrogen, lanthanide (2.42 mmol), PhSSPh (0.791 g, 3.62 mmol), and Hg (0.06 g, 0.3 mmol) were combined in THE solvent (35 mL). The lightly colored solution was stirred for l day. The presence of Hg served to speed up the reaction. Elemental sulfur was added (0.058 g, 1.8 mmol. 0.75 equivalents to M), and after 3 days the solution (yellow green (Gd), blue (Nd), blue green (Pr)) was filtered to remove a trace of black solid, and the filtrate was layered with hexane. Colorless (Gd), light blue (Nd), or light green (Pr) crystals of M3S6(SPh),2(THF)8.

THF, 9 were collected (0.44-0.57 gm yields range from 42-57% g. with longer saturation times giving larger yields). The compounds do not melt but begin turning yellow between 165 0C (Pr) and 175°C (Gd)). Upon isolation, the crystals lose THE and become amorphous within hours. Elemental analyses are consistent with the structure (less lattice THF) if the compound is analyzed immediately after isolation (i.e., analytical calculated for Pr8S6(SPh),2(THF)8: C, 38.9; H.3.90. Found: C, 37.1; H, 3.80), but the materials continue to lose coordinated THE upon standing at room temperature.

The IR and NMR spectra are essentially identical for all three compounds. 'H NMR (THF-d8) revealed only peaks due to displaced THF(ppm): 1.754(t), 3.604(m). IR (KBr, Nujol): 3151(w), 2923(s), 2854(s), 2724(w), 2672(w), 2199(w), 2036(w), 1947(w). 1874(w), 1813(w), 1571(m), 1461(s), 1377(s), 1305(w), 1262(w), 1169(m), 1154(m), 1113(w), 1075(m), 1022(m), 973(w), 917(w), 863(w), 803(w), 736(m), 724(m), 691(m). 662(w), 481(m) cm-1. Unit cell data (-120°C): Pr; triclinic space group P-1, with a = 17.661(5)Å, b = 18.297(5)Å, c =20.490(5)Å, a = 102.84(2)°, p = 94.56(2)°, y = 94.17(2)°, V = 6407(3)Å 3. Nd: triclinic space group P-1, with a = l7.632(4)A, b = 18.236(3)Å, c = 20.441(2)Å, a = 102.92(1)0, p = 94.65(2)0 , y = 94.21(2)0 , V = 6357(2)Å3. Gd: triclinic space group P-1, with a = 17.513(4)A , b = 18.136(4)A , c = 20.382(4)Å, a = 102.94(2)0 , p = 94.39(2)0 ,y = 93.72(2)0, V = 6268(3)A3 , Z = 2, pcalc = 1.878 g/cm-3 (Mo Ka radiation at -1200C. Tb: monoclinic space group C2/c, with a = 26.706(8)A , b =20.751(5)A, c = 46.95(l)A , p = 90.21(2)0, V = 26020(1 1)A3. Sm (from THF/DME: tetragonalspace group I4/m. with a = 18.256(6)A , c = 21.478(7)Å, and V = 7158(4) Å3. These analogous MSe6 (EPh),, clusters can be obtained from the reaction of M(EPh)3 with Se,, and the analogous MTe (EPh) 12 clusters can be prepared from the reaction of M(EPh)3 with elemental Te.

The invention being thus described. it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention and all such modifications are intended to be included within the scope of the following claims.