The synthesis of a dinuclear anionic carbonyl derivative of manganese, [N(PPh3)2][Mn2(µ-PPh2)(CO)8], and its reactions with complexes of Group 1B and Group 8A metals to give mixed-metal clusters: comparative study of the X-ray crystal structures of [N(PPh3)2][Mn2(µ-PPh2)(CO)8], [Mn2{µ-Au(PMe2Ph)}(µ-PPh2)(CO)8], and [Mn2(µ-H)(µ-PPh2)(CO)8]

Abstract

The first anionic dinuclear carbonyl derivative of manganese, [Mn₂(µ-PPh₂)(CO)₈]^–, has been prepared by deprotonation of [Mn₂(µ-H)(µ-PPh₂)(CO)₈](1) and isolated as its bis(triphenylphosphine)-iminium salt, [N(PPh₃)₂][Mn₂(µ-PPh₂)(CO)₈](2). Complex (2) reacts with complexes of Group 1B and Group 8A metals to give the mixed-metal complexes, [Mn₂(µ-ML)(µ-PPh₂)(CO)₈][M = Cu, L = PEt₃(3a); M = Ag, L = PEt₃(3b); M = Au, L = PMe₂Ph (3c); M = Au, L = PPh₃(3d); M = Au, L = PEt₃(3e)], and [Mn₂{µ-M(PPh₃)L}(µ-PPh₂)(CO)₈][M = Rh, L = PPh₃(4a); M = Ir, L = CO (4b)]. Complex (3e) ionises in solution in the presence of excess PEt₃ to give [Au(PEt₃)₂]⁺ and [Mn₂(µ-PPh₂)(CO)₈]^–. The crystal structures of (2) and (3c) have been determined and are discussed in relation to that of (1), the structure of which has been redetermined in a different crystalline modification to that previously reported, and to a greater degree of accuracy than that originally achieved. Crystals of (1) are Triclinic, space group C, with a= 8.157(2), b= 19.246(3), c= 14.510(2)Å, β= 89.10(3), β= 106.31 (3), γ= 90.07(3)°, Z= 4; 2 710 reflections with I 3σ(I)[3 < θ < 25°], refined to R= 0.0493 and R′, = 0.0506. Complex (2) crystallises in space group P2₁/c with a= 10.172(2), b= 30.441(4), c= 17.076(3)Å, β= 100.88(3)°, Z= 4; 4 005 reflections [I 3σ(I), 3 < θ < 25°], refined to R= 0.067 and R′= 0.063. Crystals of (3c) are Monoclinic, space group P2₁/c, a= 13.360(2), b= 14.645(1), c= 17.336(3)Å, β= 115.20(1)°, Z= 4; 1 843 reflections [I 2σ(I), 3 < θ < 22.5°], refined to R= 0.079 and R′= 0.065.