Enhanced slip distortions in 1-phenyl-2-methyldicarbaplatinaboranes. Conformational destabilisation in the isomerisation of 1-phenyldicarbaplatinaboranes
摘要:
The compounds Tl-2[7-Ph-8-Me-7,8-nido-C2B9H9], [C5H10NH2] [7-Ph-8-Me-7,8-nido-C2B9H10], 1-Ph-2-Me-3,3-L(2)-3,1,2-PtC2B9H9 [L = PMe(2)Ph, PEt(3), PPh(3) or P(C(6)H(4)Me-p)(3)] have been prepared and characterised. The platinum complexes were obtained from the reactions between Tl-2[7-Ph-8-Me-7,8-nido-C2B9H9] and the appropriate [PtCl2(PR(3))(2)] species. Crystallographic studies upon the compounds where L = PEt(3) and two crystalline modifications of that where L = PPh(3) afforded evidence of a substantial influence of intramolecular crowding upon the observed structures, so that the lateral slippage (Delta) of the metal fragment is significantly enhanced: Delta = 0.74 and 0.94 and 0.91 Angstrom respectively. These compounds do not isomerise under conditions which produce rearrangement in the corresponding (less-congested) derivatives of 1-phenylcarbaborane, consistent with the proposed conformational destabilisation in the latter system.