Reaction between [Re3H3(CO)12] and the diphosphine ligands Ph2P-CH2PPh2 and (EtO)2POP(OEt)2 : X-ray crystal structures of [Re2H2-(CO)6(Ph2PCH2PPh2)] and [Re3H3(CO)8{(EtO)2POP(OEt)2}2]

Abstract

The reactions of [Re₃H₃(CO)₁₂] with the diphosphine ligands Ph₂PCH₂PPh₂(dppm), (EtO)₂POP(OEt)₂(tedip), and Ph₂PCH₂CH₂PPh₂(dppe) have been studied. From the reaction with dppm, the known complex [Re₂-(CO)₈(dppm)](1) has been isolated together with the three new complexes [Re₂H₂(CO)₆(dppm)](2), [Re₃H₃-(CO)₁₀(dppm)](3), and [Re₃H₃(CO)₈(dppm)₂](4). The reaction of [Re₃H₃(CO)₁₂] with tedip proceeds similarly to that with dppm, forming products (5), (6), and (7) analogous to (2), (3), and (4), and a second isomer of (6), [Re₃H₃(CO)₁₀(tedip)](8), in which a tedip ligand chelates a single rhenium atom in an axial–equatorial configuration. Protonation of (7) gives the cation [Re₃H₄(CO)₈(tedip)₂]+(10). Complexes (2) and (7) have been characterised by X-ray structure analysis by conventional heavy-atom methods using room-temperature diffractometer data. Complex (2) crystallises in space group Pbca with Z = 8, a= 19.220(5), b= 29.820(9), and c= 10.655(4)Å, and (7) in space group P2₁/c with Z = 4, a= 18.053(6), b= 16.211(5), c= 14.800(3)Å, and β= 102.41(2). Final residuals were R= 0.033 and 0.0696 for 2 247 and 3 398 unique observed intensity data respectively. In (2) the dppm ligand and two hydride ligands bridge the (formal) Re–Re double bond. In (7) the Re₃(µ-H)₃ core of [Re₃H₃(CO)_{1 2}] is preserved with four axial sites occupied by the two tedip ligands which bridge two edges of the Re₃ triangle. The reaction between [Re₃H₃(CO)₁₂] and dppe gives [ReH(CO)₃(dppe)] as the major product; a minor product isolated in low yield is formulated as [Re₂H(CO)₇(Ph₂PCH₂CH₂PPhC₆H₄)](9).