Borabenzene Derivatives. 30. Bis(1-methylboratabenzene) Compounds of Germanium, Tin, and Lead. First Structural Characterization of Facial Bonding of a Boratabenzene to a p-Element and the Structures of Pb(C5H5BMe)2 and Its 2,2‘-Bipyridine Adduct,1

Abstract

Bis(1-methylboratabenzene)lead, Pb(C5H5BMe)2 (1), was synthesized by the reaction of Li(C5H5BMe) with PbCl2 as a low-melting (mp 60 °C) thermochromic yellow crystalline solid (63%). The lighter homologues Sn(C5H5BMe)2 (2) and Ge(C5H5BMe)2 (3) were obtained from 1-methyl-2-(trimethylstannyl)-1,2-dihydroborinine, 2-(Me3Sn)C5H5BMe, and SnCl2 and GeI2, respectively, as colorless liquids (70%). The plumbocene analogue 1 possesses a monomeric bent-sandwich structure with a bending angle of 135.2(3)°. Compound 1 forms addition compounds with nitrogen bases such as 1·TMEDA (6) and 1·bipy (7). Adduct 7 has a bent-sandwich structure with the 2,2‘-bipyridine ligand in the pseudoequatorial plane; the bending angle is 139.1(5)°.