Cyclometallation Reactions. XXI. Some Chemistry of Binuclear Manganese Complexes Derived From Azobenzene: X-Ray Crystal-Structures of {Mn (CO)₄}₂(μ- C₆H₄N=NC₆H₄) and {Mn (CO)₄}{ Mn (CO)₃[P(OPh)₃]}(μ-C₆H₄N=NC₆H₄)

Abstract

The reaction between azobenzene and Mn (CH₂Ph)(CO)₅, carried out in refluxing n-octane, afforded the binuclear complex {Mn (CO)₄}₂(μ- C₆H₄N=NC₆H₄) (2) as the first isolable product; subsequent reaction with azobenzene gave Mn (C₆H₄N= NPh )(CO)₄. With P( OPh )₃, the binuclear complex undergoes CO substitution but not hydrogen transfer, to give {Mn (CO)₄}{ Mn (CO)₃[P(OPh)₃]}(μ-C₆H₄N=NC₆H₄)(3). The X-ray crystal structures of the title complexes have been determined. Compound (2) crystallizes in the monoclinic space group P2₁/c with unit cell dimensions a 10.161(2), b 23.586(4), c 13.091(4)Ǻ, β 97.10(2)° with Z = 6; crystals of (3) are triclinic, space group Pī , a 12.886(3), b 13.920(3), c 10.428(7)Ǻ, α 97.11(4),β 102.60(4), γ 81.78(2)°. The structures were refined by a full-matrix least-squares procedure to final R 0.041 and Rw 0.048 for 3459 reflections with I ≥ 2.5σ(I) for (2), and R 0.095 and Rw 0.106 for 3406 reflections for (3).