Reactivity of bimetallic dibridged complexes Cp 2Ta(H)(μ-H)(μ-PMe 2)M′(CO) 4 (M′ = Cr, Mo, W) toward two-electron donor ligands L (L = PR 3, Me 2P(CH 2) nPMe 2). Synthesis of linear trinuclear chain complexes Cp 2Ta(H) 2(μ-PMe 2)M′(CO) 4(Me 2P(CH 2) 2PMe 2)Cr(CO) 5 (M′ = Mo, W)

Abstract

The reaction of the heterobimetallic phosphido- and hydrido-bridged complexes Cp 2TaH(μ-H)(μ-PMe 2)M′(CO) 4 (M′ = Cr, Mo, W) ( 1–3) with phosphines (L = PPh 2Me, PMe 2Ph) or diphosphines (L = dmpm, dmpe) leads to Cp 2Ta(H) 2(μ-PMe 2)M′(CO) 4(L) ( 1a, 1b, c, d-3b, c, d) with L regiospecifically coordinated to M′. Except for L = PPh 2Me, the reaction is stereospecific, since a cis arrangement (with respect to the PMe 2 bridge) on the M′ site is obtained. The new compounds Cp 2Ta(H) 2(μ-PMe 2)M′ (CO) 4(Me 2P(CH 2) 2PMe 2) (M′ = Mo, W) are able to bind [Cr(CO) 5] fragments affording the linear trinuclear chain compounds Cp 2Ta(H) 2(μ-PMe 2)M′(CO) 4(Me 2P(CH 5) ( 4,5). All new complexes have been fully characterized by NMR and IR spectroscopy, and by their elemental analyses.