Synthesis and characterization of novel monocarbollide exo-closo-(π-arene)biruthenacarboranes [(PPh3)mClRu(η6-C6H5R)Ru′CB10H11-n(OMe)n] (where R = H, m=2, n=1; R = μ-PPh2, m=1, n=0, 1)

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-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-RuClPPh3(mu,eta(6)-C6H5PPh2)}-7,11-(mu-H)(2)-2,1-RuCB10H8R] (5, R = H; 6, R = 6-MeO; 7, R = 3-MeO) and [closo-2-(eta(6)-C6H6)-10,11,12-{exo-RuCl(PPh3)(2)}-10,11,12-(mu-H)(3)-2,1-RuCB10H7R1] (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-(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 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(PPh3)(2)} fragment about two adjacent triangular cage boron faces B(7)B(11)B(12) and B(8)B(9)B(12).