title: Synthesis and structural characterization of 14-vertex germa-, stanna-, and plumba-carboranes.
abstract: This article reports the synthesis and structures of several 14-vertex germa-, stanna-, and plumba-carboranes of the MC2B11 system. The reaction of GeCl2·dioxane, SnCl2 or Pb(OAc)2 with [8,9-(CH2)3-8,9-C2B11H11][Na2] in THF gave, after recrystallization from bidentate ligands such as bipyridine, 4,4'-dimethyl-2,2'-bipyridine, phenantroline and 1,2-bis(diphenylphosphino)ethane (dppe), eight 14-vertex p-block metallacarboranes 2,3-(CH2)3-1-(2',2''-bipyridine)-1,2,3-GeC2B11H11 (1), 2,3-(CH2)3-1-(4',4''-dimethyl-bipyridine)-1,2,3-GeC2B11H11 (2), 2,3-(CH2)3-1-(1',10'-phenantroline)-1,2,3-GeC2B11H11 (3), 2,3-(CH2)3-1-(2',2''-bipyridine)-1,2,3-SnC2B11H11 (4), 2,3-(CH2)3-1-(4',4''-dimethyl-bipyridine)-1,2,3-SnC2B11H11 (5), 2,3-(CH2)3-1-(1',10'-phenantroline)-1,2,3-SnC2B11H11 (6), 2,3-(CH2)3-1-(dppe)-1,2,3-SnC2B11H11 (7) and 2,3-(CH2)3-1-(2',2''-bipyridine)-1,2,3-PbC2B11H11 (8) in high isolated yields. Single-crystal X-ray analyses reveal that they adopt a distorted-bicapped-hexagonal antiprism geometry, in which the p-block metal atom slips away from the above center of the C2B4 bonding face towards the boron side, leading to an η(4) bonding mode. The results suggest that [nido-8,9-(CH2)3-8,9-C2B11H11](2-) is a redox inactive species and a good π-ligand for transition metals and p-block elements.
authors.affiliation: Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin NT, Hong Kong, China. zxie@cuhk.edu.hk.
authors.forename: Fangrui
authors.initials: F
authors.lastname: Zheng
authors.forename: Zuowei
authors.initials: Z
authors.lastname: Xie