Metallaheteroborane chemistry. Part 6. Synthesis of closo-[2-(η-ligand)-1,2-TeMB₁₀H₁₀] complexes with M(η-ligand)= Rh(η⁵-C₅Me₅)(<b>1</b>), Ru(η⁶-p- MeC₆H₄Prⁱ)(<b>2</b>), Ru(η⁶-C₆Me₆)(<b>3</b>), and of nido-[6-(η⁶-C₆Me₆)-8-(OEt)-6-RuB₉H₁₂](<b>4</b>), their characterisation by nuclear magnetic resonance spectroscopy and, for (<b>1</b>) and (<b>3</b>), by X-ray crystallography

Abstract

The reaction between [{Rh(η5-C5Me5)Cl2}2] and nido-[7-TeB10H11]– in CH2Cl2, gave closo-[2-(η5-C5Me5)-1,2-TeRhB10H10](1) in moderate yield (65%). Similar reactions with [{Ru(η6-arene)Cl2}]2(η6-arene =p-MeC6H4Pri or C6Me6) in CH2Cl2 gave closo-[2-(η6-arene)-1,2-TeRuB10H10] complexes, (2)(40%) and (3)(60%) respectively. Reaction between [{Ru(η6-C6Me6)Cl2}2] and nido-[7-TeB10H11]– in EtOH produced nido-[6-(η6-C6Me6)-8-(OEt)-6-RuB9H12](4) in moderate yield (38%) together with (3)(15%). Compounds (1)–(4) were characterised by multielement n.m.r. spectroscopy and, for (1) and (3), by X-ray diffraction analyses. Crystals of (1) were orthorhombic, space group P212121, Z= 4, a= 988.3(1), b= 1 392.6(2), and c= 2 745.1(3) pm. The structure was refined to a final R of 0.0364 and R′ of 0.0397 for the 3 637 reflections with I 1.5σ(I). There were two molecules in the asymmetric unit. Crystals of (3) were monoclinic, space group C2/m, Z= 4, a= 1 850.8(2), b= 882.3(1), c= 1 216.5(1) pm, and β= 100.84(1)°. The structure was refined to a final R of 0.0286 and R′ of 0.0403 for the 1 793 reflections with I 2.0σ(I). Both (1) and (3) contained closed TeMB10 dodecahedra with Te and M adjacent. The metal tellurium distances were 252.9(4) and 253.6(4) pm in the two independent molecules of (1) and 254.9(2) in (3). Almost all comparable interatomic distances in the MTeB10 cages of (1) and (3) were remarkably similar. Features in the bonding of the metals to the telluraborane and organic ligands are discussed in terms of the relevant molecular orbital interactions.