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An empirical and computational study is conducted to elucidate the methods in which {M[L.sub.2]} fragments bind to the four different types of six-atom carborane faces (III- VI above) in supraicosahedral metallacarboranes. Clear patterns are visible in the conformation of the {M[L.sub.2]} fragments with respect to the carborane ligand in these species.

The anion [2,2-(CO)2-closo-2,1-NiCb10H11](super -) is prepared, which represents for the nickel triad the parent compound of half-sandwich, carbonyl-metal-monocarbollide clusters. This anion is an analogue of the presume [Ni-(CO)2(eta-C5H5)](super +) cation, but it is noted as a very stable, anionic Ni(II)-carbonyl complex.

The study shows that the manganacarborane dianion in [N(PPh3)2][NEt4][1,1,1-(CO)3-2-Ph-closo-1,2-MnCB9H9] reacts with cationic transition metal-ligand fragments to give products in which the electrophilic metal groups (M') are exo-polyhedrally attached to the {closo-1,2-MnCB9} cage system. Details of the x-ray diffraction studies carried out to elucidate the structures encountered in compounds are discussed.

Research has been conducted on the diaonic molybdenacarborane. The preparation of this compound has been carried out and the results indicate that it is readily oxidized by cage-carbon to cage-boron transfer of NMe (sub)3 group.

Research has been conducted on the metallacarnoranes. The preparation of the metal complexes demonstrating the aminocarborane ligand versatility has been carried out and investigated and the results are described.

The viability of (K(18-crown-6))(RuH(PPh3)2(eta(super 5)-7,8-C2B9H11))(super -) as a precursor of new ruthenacarborane complexes has been studied. The anion is readily accessible as the potassium salt from the exo-nido charge-compensated ruthenacarborane complex (5,6,10-(RuCl(PPh3)2)-5,6,10-mu-(H)3-10-H-7,8-C2B9H8). Results indicate that it can be used to synthesize compounds with Ru-Ru, Ru-Cu and Ru-Au bonds.

Compounds with a number of groups exopolyhedrally linked to the MCB10 cage system's metal atom are prepared with the use of a monocarbon metallacarborane with a closo-icosahedral framework as a reagent. The dimetal compounds (PtHgPh(PEt3)2(eta to the power of 5-7-CB10H11)) (3c), (3a, M = Au; 3b, M=Cu) and (PtM-(PEt3)2(PPh3)(eta to the power of 5-7-CB10H11)) are yielded by reactions with (HgC1Ph), (CuC1(PPh3))4 and (AuC1(PPh3)) respectively.

The formation of metallated azobenzene derivatives by fluorine-abstraction reactions using nucleophilic transition metal reagents has been achieved; the structure of an ortho-metallated complex, derived from decafluoroazobenzene and also containing a Ph2P(C6H4C5H 4) ligand is described.

Cobaltacarborane carbonyl complexes of [Co2(CO)2(eta5-7,8-C2HB9H11)2] were synthesized by the reaction of [Co2(CO)8] and nido-7,8-C2B9H13 in CH2Cl2. The cobaltcarborane carbonyl complex is an efficient precursor for other complexes with a closo-3,1,2-CoC2B9 cage system that is bonded to other ligands by cobalt molecules. The isomers of the complex have internuclear separations and angles that are composed of two Co(CO)(eta5-7,8-C2B9H11) fragments that are linked by Co-Co bonds with B-H to Co linkages.

[RhX(PPh3)(eta5-7-NH2But-8-CH2CO2Et-7-CB10H9)] (X = Br or Cl) was produced by the reaction of the reagents of monocarbon rhodacarborane complex with one mol equiv. of N2C(H)CO2Et in CH2Cl2. The insertion of an organic fragment into the BH bond of the monocarbon carborane resulted in the formation of the product. The rhodium atom of the Br-containing monocarbon rhodacarborane complex is coordinated by the Br[Rh-Br 2.5116(5) angstrom] and the PPh3 groups.

The reaction of (RhX(PPh3)3) with nido-7-NH2Bu-7-CB10H12 in toluene produces the 16-electron compound, (RhX(PPh3)(eta(super 5)-7-CB10H10)). The X-ray crystallographic structure of the compound is similar to that of the nido component used during the synthesis. However the bond length is short due to the addition of Cl ions in some of the Br sites. Since the cages retain the triangulated closo-icosahedral framework, the electron deficiency is metal centered.

A new synthetic methodology enables the preparation of Pd(II) complexes having C-methyl-substituted icosahedral closo-PdC2B9 fragments, with the Pd carrying the donor ligands. At ambient temperatures, a Pd cod complex (cod-cycloocta-1, 5-diene) undergoes a cage transformation from a closo-3,1,2-PdC2B9 to the closo-2,1,4-PdC2B9 cage structure. Dissociation of the cod group induces intramolecular rearrangement, while complexes with strongly bound ligands do not undergo this polytopal rearrangement. X-ray crystallographic studies help determine the structures of various cage complexes.

Analysis of novel carborane complexes of platinum and nickel revealed the importance of allyl(carborane) metal reagents as precursors for polynuclear and mononuclear metallacarborane complexes of group 10 metals. A C4 chain bonding mode in these late transition metals was observed. Carborane complexes act as useful reagents during the synthesis of new mononuclear compounds belonging of group 6 metals.

Two anions (10-endo-(Au-(PPh3))-7,8-R'2-nido-7,8-C2B9H9)- and (10-endo-H-7,8-R'2-nido-7, 8-C2B9H9)-, are isoglobally mapped to reveal the yielding of slats from one anion. Gold bonding to temporary elements is seen in compounds synthesized by these salts, used as reagents. Numerous gold-rhodium and -iridium compounds are prepared by employing this method. The carborane cage ligands participate actively, resulting in the rare molecular organization of the products.

X-ray diffraction studies, microanalysis and nuclear magnetic resonance spectroscopy analyses characterized the products derived from the reactions of (closo-1,2-Me2-3- triple bond CR -3,3- CO 2-3,1,2-MC2B9H9)- and (closo-1,6-Me2-4- triple bond CC6H4Me-4 -4,4- CO 2-4,1,6-MC2B10H10)-. Results showed that the carborane CMe groups occupied separate vertices and dissociated at relatively low temperatures. Furthermore, the rearrangement process was found to be reversible.

The complex salts related to the salts of the anions (10-endo-(Au-(PPh3))-7,8-R2-nido-7,8-C2B9H9)-, where R may be Me or H, is prepared with the incorporation of an Au(PPh3) fragment which associates itself with a nido-C2B10 cage system. Two isomeric forms of the Au(PPh3)+ and H+, which are found to be isolobal, exist. A kinetically unstable isomer is produced first by protonation, but later the isomer becomes thermodynamically stable.

The generation of a [[B-PH[Ph.sub.2]] vertex in a ferramonocarbolide cage system via reaction between P[Ph.sub.2]Cl and Ti[P[F.sub.6]] is demonstrated. The results provide insight into the deprotonation of the phosphine ligand and subsequent reaction with a variety of substrates results in the formation of both 4- and 5-membered heteroatomic intermolecular rings.

The photochemical synthesis of an isomeric pair of anionic dirhenacarboranes and subsequent reactions leading to heterometallic compounds are described.

The formation of penta- and hexaruthenacarborane clusters by using {C[B.sub.n]} (n = 8, 9) monocarborane cage substrates is described. It is shown that the polyruthenium 'raft' moieties have contributed to closed 12-vertex {[Ru.sub.3C[B.sub.8]} clusters with hypercloso geometries.

Studies relating to the metal atom arrangement reveal that iridium and iron moieties exchange exo- and endo-polyhedral sites with respect to the ten-vertex metallacarborane. X-ray diffraction studies upon compounds confirmed their novel structural features. Some preliminary reactivity studies upon these compounds are reported.

The reagent [arachno-4-CB8H14] reacts with [Fe3(CO)12] in tetrahydrofuran (THF) at reflux temperatures, followed by the addition of [N(PPh3)2]Cl to afford [N(PPh3)2][4,9-{Fe(CO)4}-9,9,9-(CO)3-arachno-9,6-FeCB8H11]. Several 10-vertex ferracarboranes are prepared starting from 8-boron atom substrates and their reactivity is studied.

It been shown that compounds of the forms [2,2-L2-closo-2,1,7-NiC2B9H11], which display interesting dynamic properties in solution is obtained by protonation of the species [NEt4]-[2-(eta3-C3H4R)-closo-2,1,7-NiC2B9H11] (R = H, Ph) in the presence of donors (L = CO, CNBut, L2 = diene).