Trinuclear metal clusters of cobalt and rhodium containing bridging nitrogen-donor ligands

The synthesis of two novel trinuclear organometallic complexes based upon the series prepared by Barnes et al. (Organometallics, 1990, 9, 1021) is presented. Reaction of (η⁵-C₅Me₅Co)₂ (μ-CO) (μ-NO) (1) with (η⁵-C₅H₅Co) (C₂H₄)₂ yields (η⁵-C₅Me₅Co)₂ (μ₃ - CO)(μ₃ - NO) (η⁵-C₅H₅Co)(4), a 47 electron paramagnetic trinuclear cluster. Attempted dinuclear exchange reactions between 4 and (η⁵-C₅Me₅Rh)₂(μ-CO)₂ (2) yield no novel trinuclear clusters containing the nitrosyl moiety. Likewise, reactions of 1 with members of the series synthesized by Barnes et al. do not yield 4 as a product. The X-ray crystal data for 4 are as follows: monoclinic, P2₁/n, a = 8.692(10)Å, b= 17.482(2)Å, c = 16.278(3)Å, β= 103.550(10)°, Z = 4, R(F) = 2.92%. Reaction of (η⁵-C₅Me₅M)x(μ₃-CO)₂(η⁵-C₅H₅Co)_3-x (M= Co, Rh; x = 1, 2 ) with N₂CHCH₃ yields a 48 electron diazoalkane adduct, where the diazoalkane assumes a monohapto-, triply- bridging coordination mode, as verified by X-ray crystal analysis of 3 (M = Co, x = 1) . A similar reaction of (η⁵-C₅Me₅Co) (μ₃-CO)₂(η⁵-C₅H₅Co)₂ with N₂CH₂ yields a diazoalkane adduct, while reaction of (η⁵-C₅Me₅Rh) (μ₃-CO)₂(η⁵-C₅H₅Co)₂ with N₂CH₂ yields a trinuclear carbene complex which undergoes isomerization in solution. The X-ray crystal data for 3 are as follows: monoclinic, P2₁/c, a= 8.846(2)Å, b= 9.701(2)Å, c= 28.587(5)Å, β= 97.825(14)°, Z- 4, R(F)= 3.31%.