Synthesis and characterisation of tungsten and rhenium aluminopolyhydrides: X-ray crystal structures of (Me3P)3H3W(µ-H)2Al(H)(µ-OBun)2Al(H)(µ-H)2WH3(PMe3)3 and (Me3P)3H3W(µ-H)2Al(H)(µ-H)2WH3(PMe3)3

Abstract

The reaction of WCl₄(PMe₃)₃ with LiAlH₄ in refluxing tetrahydrofuran leads to the aluminopolyhydride, (Me₃P)₃H₃W(µ-H)₂Al(H)(µ-OBuⁿ)₂Al(H)(µ-H)₂WH₃(PMe₃)₃(1), whereas in diethyl ether the product is (Me₃P)₃H₃W(µ-H)₂Al(H)(µ-H)₂Al(H)(µ-H)₂WH₃(PMe₃)₃(2). Addition of NNN′N′-tetramethylethylenediamine to a toluene solution of (2) results in the formation of (Me₃P)₃H₃W(µ-H)₂Al(H)(µ-H)₂WH₃(PMe₃)₃(3). The rhenium analogues of (1) and (2), namely compounds (Me₂PhP)₃H₂Re(µ-H)₂Al(H)(µ-OBuⁿ)₂Al(H)(µ-H)₂ReH₂(PMe₂Ph)₃(4) and (Me₂PhP)₃H₂Re(µ-H)₂Al(H)(µ-H)₂Al(H)(µ-H)₂ReH₂(PMe₂Ph)₃(5) have been obtained from ReCl₃(PMe₂Ph)₃. The heavy-atom structures of (1) and (3) have been confirmed by X-ray crystallography. Hydrogen-1, ³¹P, and ²⁷Al n.m.r. spectra are reported and the fluxional behaviour of the compounds discussed.