Synthesis and reactivity of homo-bimetallic Rh and Ir complexes containing a N,O-donor Schiff base

Binuclear complexes {(η⁵-C₅Me₅)RhCl}₂(μ-bsh)] (1) and {(η⁵-C₅Me₅)IrCl}₂(μ-bsh)] (2) containing N,N′-bis(salicylidine)hydrazine (H₂bsh) are reported. The complexes 1 and 2 reacted with EPh₃ (E = P, As) to afford cationic complexes (η⁵-C₅Me₅)Rh(PPh₃)(κ²-Hbsh)]PF₆ (3), (η⁵-C₅Me₅)Rh(AsPh₃)(κ²-Hbsh)]PF₆ (4), (η⁵-C₅Me₅)Ir(PPh₃)(κ²-Hbsh)]PF₆ (5), and (η⁵-C₅Me₅)Ir(AsPh₃)(κ²-Hbsh)]PF₆ (6) which were isolated as their hexafluorophosphate salts. Representative complexes 3 and 5 have been used as a metallo-ligand in the synthesis of binuclear complexes (η⁵-C₅Me₅)RhCl(μ-bsh)Ru(η⁶-C₁₀H₁₄)Cl]PF₆ (7) and (η⁵-C₅Me₅)IrCl(μ-bsh)Ru(η⁶-C₁₀H₁₄)Cl]PF₆ (8). The complexes under study have been fully characterized by analytical and spectral (FAB/ESI-MS, IR, NMR, electronic and emission) studies. Molecular structures of 1, 2, 3 and 5 have been determined crystallographically. Structural studies on 1 and 2 revealed the presence of extensive inter- and intra-molecular C-H···O and C-H···π weak bonding interactions. The complexes 1, 2, 3 and 5 moderately emit upon excitation at their respective MLCT bands.