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The reaction of nido-B10H12CNMe3 with Rh(PPh3)3Cl resulted to the formation of a novel monocarbon hydridorhodacarborane closo-2,7-(PPh3)(sub 2)-2-H-2-Cl-1-(NMe3)-2,1-RhCB10H9. This was identified as the first mononuclear hydride complex having an icosohedral monocarbon carborane ligand in its molecular structure. X-ray diffraction study confirmed the product to be a closo-hydridirhodacarborane consisting of quaternary nitrogen and phosphorus groups bonded to a monocarbon carborane ligand and an Rh center spanning 18 electrons.

Research has been conducted on the electronic and cluster structures of the electon-deficient closo-metallacarboranes. The example of the structurally characterized 8-vertex monocarbon metallacarborane derived from the monocarbon carborane is presented.

N-quarterization of the climeric anion present in (PPN) (Ph3PRhB10H10CNH2)2H (1) yields mononuclear monocarbon closo-rhodacarboranes. The mixture mononuclear complexes formed due the combination of the salt 1 with 0.20 milli litres of crotyl bromide in 25 ml of CH2Br2 at 25 degrees celsius is segregated into the mononuclear complexes. The separation is carried out by employing column chromatography on silica gel (eluent CH2Cl2). The complexes exhibit a proton NMR spectra, characterized by complex multiplets from phosphorus triphenyl (PPL3) ligands, in association with rhodium atoms. In addition to these signals the spectra contains signals from sigma-crotyl groups.

The monocarbon carborane [Cs][nido-7-CB10H13] reacts with the 16-electron [RuCl2(PPh3)3] in a solution of benzene/ methanol in the presence of N,N,N′,N′-tetramethylnaphthalene-l,8-diamine as the base to give a series of 12-vertex monocarbon arene-biruthenacarborane complexes of two types: [closo-2-{7,11-exo-RuClPPh3(μ,η6-C6H5PPh2)}-7,11-(μ-H)2-2,1-RuCB10H8R] (5, R = H; 6, R = 6-MeO; 7, R = 3-MeO) and [closo-2-(η6-C6H6)-10,11,12-{exo-RuCl(PPh3)2}-10,11,12-(μ-H)3-2,1-RuCB10H7R1] (8a, R1 = 6-MeO; 8b, R1 = 3-MeO, inseparable mixture of isomers) along with trace amounts of 10-vertex mononuclear hypercloso/isocloso-type complexes [2,2-(PPh3)2-2-H-3,9-(MeO)2-2,1-RuCB8H7] (9) and [2,5-(Ph3P)-2-Cl-2-H-3,9-(MeO)2-2,1-RuCB8H6] (10). Binuclear ruthena-carborane clusters of both series were characterized by a combination of analytical and multinuclear NMR spectroscopic data and by single-crystal X-ray diffraction studies of three selected complexes, 6–8. In solution, isomers 8a,b have been shown to undergo the isomerization process through the scrambling of the exo-{RuCl-(PPh3)2} fragment about two adjacent triangular cage boron faces B(7)B(11)B(12) and B(8)B(9)B(12). [ABSTRACT FROM AUTHOR]

Reactions of [OsCl2(PPh3)3] 1 with the [NEt4]+ salts of the [6-Ph-nido-6-CB9H11]− anion 2 and the [arachno-6-CB9H14]− anion 3 each proceed selectively in methanol solution with the elimination of one boron-containing fragment from the starting cluster polyhedron, yielding together a short series of three novel 10-vertex hydridoosmamonocarbaboranes of isocloso {OsCB8} cluster geometry. [Copyright &y& Elsevier]

Abstract: The heating of the isomeric [1-(η6-1,4-Me2C6H4)-3-Cl-isonido-1,2,4-RuC2B8H9] (1) or [1-(η6-1,4-Me2C6H4)-6-Cl-isonido-1,2,4-RuC2B8H9] (2) complexes (i) in a 1,4-Me2C6H4 solution at 85 °C as well as (ii) in a melt at 165 °C afforded mixtures of isomeric isonido- and closo-ruthenacarboranes, which differ in the positions of the chlorine substituent and the carbon atoms in the cage ligand. Structures of all new isomeric complexes have been established on the basis of analytical and multinuclear NMR data and were characterized by single-crystal X-ray diffraction studies. Also presented are the results of the quantum chemical calculations for the ground and the transition states of the reaction (i), which proved to be basis for the suggestion of interconversion scheme for these isomers. [Copyright &y& Elsevier]

Treatment of a recently reported complex [Ph 4 P][closo,nido-CoH(2,4-C 2 B 8 H 10 )(7,8-C 2 B 8 H 11 )] (1) either by H 2 O 2 in acetone or NaH in THF leads to the loss of both the bridging and terminal hydrides yielding the diamagnetic salt of an anionic commo-cobaltacarborane [Ph 4 P][Co(2,4-isonido-C 2 B 8 H 10 ) 2 ] (2) with the {CoC 2 B 8 }-cluster units adopting a distorted skeletal geometry of the isonido-type. The anionic commo complex 2 reacts with in situ generated cationic [CuPPh 3 ] + species to give stable copper-cobalt zwitterion [Ph 3 PCu][Co(2,4-isonido-C 2 B 8 H 10 ) 2 ] (3) with four two-electron, three-center (B-H) 4 ···Cu bonds, and exhibits no fluxional behavior in solution. Complex 3, at the same time, in CH 2 Cl 2 in the presence of 2-fold excess of PPh 3 readily converts to a new anionic species [(Ph 3 P) 3 Cu][Co(2,4-isonido-C 2 B 8 H 10 ) 2 ] (4) which retains initial isonido geometry. All newly obtained diamagnetic commo complexes were characterized by a combination of analytical and multinuclear NMR spectroscopic data and by single-crystal X-ray diffraction studies of complexes 2 and 3.

The monocarbon carborane [Cs][nido-7-CB(10)H(13)] reacts with the 16-electron [RuCl(2)(PPh(3))(3)] in a solution of benzene/methanol in the presence of N,N,N',N'-tetramethylnaphthalene-1,8-diamine as the base to give a series of 12-vertex monocarbon arene-biruthenacarborane complexes of two types: [closo-2-[7,11-exo-RuClPPh(3)(mu,eta(6)-C(6)H(5)PPh(2))]-7,11-(mu-H)(2)-2,1-RuCB(10)H(8)R] (5, R = H; 6, R = 6-MeO; 7, R = 3-MeO) and [closo-2-(eta(6)-C(6)H(6))-10,11,12-[exo-RuCl(PPh(3))(2)]-10,11,12-(mu-H)(3)-2,1-RuCB(10)H(7)R(1)] (8a, R(1) = 6-MeO; 8b, R(1) = 3-MeO, inseparable mixture of isomers) along with trace amounts of 10-vertex mononuclear hypercloso/isocloso-type complexes [2,2-(PPh(3))(2)-2-H-3,9-(MeO)(2)-2,1-RuCB(8)H(7)] (9) and [2,5-(Ph(3)P)-2-Cl-2-H-3,9-(MeO)(2)-2,1-RuCB(8)H(6)] (10). Binuclear ruthenacarborane clusters of both series were characterized by a combination of analytical and multinuclear NMR spectroscopic data and by single-crystal X-ray diffraction studies of three selected complexes, 6-8. In solution, isomers 8a,b have been shown to undergo the isomerization process through the scrambling of the exo-[RuCl(PPh(3))(2)] fragment about two adjacent triangular cage boron faces B(7)B(11)B(12) and B(8)B(9)B(12).