Tantalocene-hydride-phosphorus chemistry. Some new complexes and crystal structures of [CpCp ' TaH2(PMe2H)]PF6 (Cp = C5H5, Cp ' = (C5H2Bu)-Bu-t(Me)(2)) and Cp2Ta(H)(mu-PPh2,H)Fe(CO)(3)

摘要

The aim of this paper is to look for a better knowledge of the behaviour of bent tantalocenes that bear hydrides, phosphorus PR2X (R = Me, Ph; X = H, lone pair) and cyclopentadienyl (Cp = C5H5, Cp' = C5H2'Bu(Me)(2), Cp* = C5Me5) ligands. An orbital control of regioselectivity of insertion of the PR2 phosphide fragment of chlorophosphines PR2Cl into the central Ta-H bond of trihydrides Cp2TaH3 leading to the formation of metallophosphonium cations is discussed. Neutralisation of cationic complexes with strong bases leads either to the Ta(V)-phosphide or to the Ta(III)-phosphine species depending on the nature of the cyclopentadienyl ligand; good electron donor Cp' and Cp* rings favour the formation of Ta(V)-phosphide species, while C;H; orients neutralisation towards Ta(III)-phosphine ones. These trends are roughly confirmed by DFT calculations. The X-ray structure of the first tantalocene phosphonium ionic compound [CpCp'TaH2(PMe2H)]PF6 (Cp' = C5H2'Bu(Me)(2)) as well as that of the bimetallic complex Cp2Ta(H)(mu-PPh2,H)Fe(CO)(3) are also reported. (C) 2002 Elsevier Science Ltd. All rights reserved. [References: 52]