Reactions of ReH3(CO)(PMe2Ph)3 with Metallic Lewis Acids. Synthesis and Structural Characterization of Hydrido-Bridged Heterometallic Rhenium-Gold, Rhenium-Silver, and Rhenium-Copper Complexes

This contribution presents a study of the reactions of ReH₃(CO)(PMe₂Ph)₃ (1) with a variety of metallic Lewis acids of the coinage metals to form hydrido-bridged heterometallic rhenium-gold, rhenium-silver, and rhenium-copper complexes. The reaction of 1 with AuCl(PPh₃) proceeds with elimination of hydrogen to give the hydrido-bridged heterobinuclear rhenium-gold complex (PMe₂Ph)₃(CO)ClRe(-H)Au(PPh₃) (2). In contrast, the reactions of 1 with AgPF₆, Cu(CH₃CN)₄]PF₆ or CuCl proceed without elimination of hydrogen to give the hydrido-bridged heterotrinuclear rhenium-silver and rhenium-copper complexes (PMe₂Ph)₃(CO)HRe(-H)₂M(-H)₂ReH(CO)(PMe₂Ph)₃]PF₆ (M=Ag (3), Cu (4)) and the hydrido-bridged heterotetranuclear rhenium-copper complex (PMe₂Ph)₃(CO)HRe(-H)₂Cu(-Cl)₂Cu(-H)₂ReH(CO)(PMe₂Ph)₃ (5), respectively. The molecular structures of compounds 2 and 3 have been determined by single-crystal X-ray diffraction studies. Crystallographic data for 2: monoclinic, space group P2₁2₁2₁, a=12.804(2) Å, b=13.512(2) Å, c=24.312(3) Å, V=4206(1) ų, Z=4, and R=0.042. Crystallographic data for 3: monoclinic, space group C2/c, a=24.212(6) Å, b=13.098(3) Å, c=20.177(5) Å, b=116.40(2)°, V=5732(2) ų, Z=4, and R=0.044. The X-ray crystal structure of 2 exhibits a short contact (2.798(12) Å) between the gold atom and the CO ligand that is primarily bound to the adjacent rhenium atom, suggesting an incipient semibridging relationship.