Gaseous bis(trimethylsilyl)methyl-lithium (LiR) at ca. 413 K is a monomer with Li-C 2.03(6) A and the SiMe3 groups only slightly distorted from an eclipsed conformation with respect to each other; crystalline LiR is a polymer, having three 'molecules' of monomer in the asymmetric unit, the Li-C distances range from 2.14(3) to 2.27(2) A and average 2.19(5) A,

Nuclear magnetic resonance spectroscopic data on metallocene(1v) halogeno-alkyls and dialkyls Chemical shift (T) a

No abstract

Variable temperature l H n.m.r. spectra of Ph, C1, or H) in [2H,]toluene show that the activation free energy for rotation about the Zr-CH(SiMe,), bond is exceptionally high [11.6-15-3 kcal mol-l: R = H (a dimer in vapour or in C,H,) > C1 > alkyl > Ph] with a preference to a low temperature conformation in which the two sets of SiMe, and q-C,H, groups are diastereotopic; this is established for the crystalline state (X-ray

1982 345 Hydrazido(2-)-complexes of Tungsten-(v) and -(vI) and a Bis(diazenid0)complex of Tungsten(iv). X-Ray Crystal Structure of cis-[WCI3(NNH2)-(PMesPh),l t