FUSING NICKELOCENE AND CYCLOPENTADIENE BY 2 SILYL BRIDGES - SYNTHESISAND H-1, C-13, AND SI-29 NMR INVESTIGATION OF A PARAMAGNETIC BUILDING-BLOCK FOR HIGH-NUCLEAR METALLOCENES

Two isomers of trahydro-4,4,8,8-tetramethyl-4,8-disila-s-indacene (LH( 2)) were monodeprotonated and treated with cyclopentadienyl anion and NiBr2(THF)(1.5) to give a 72% yield of the mixed nickelocene CpNi(LH) where a cyclopentadiene is fused to a nickelocene. The analysis of the paramagnetic H-1, C-13, and Si-29 NMR spectra demonstrated that the s yn and anti isomer of CpNi(LH) formed in a ratio of 5/1. Both isomers could be deprotonated to yield the anion CpNi(L(-)). According to its C-13 NMR spectrum the bridging ligand L is not planar.