Synthesis, characterization and crystal structures of new ruthenium carbonyl clusters derived from (9-anthracenyl)diphenylphosphine

Thermal reaction of [Ru₂(CO)₆(μ-PFu ₂)(μ-η¹,η²-Fu)] (Fu=2-furyl) with (9-anthracenyl)diphenylphosphine (AnPPh₂) produces a novel diruthenium complex [Ru₂(CO)₅(μ-PFu₂)(μ- η¹,η¹,η²-C₁₄H ₈PPh₂)] (1) in good yield whereas the corresponding reaction between [(μ-H)₄Ru₄(CO)₁₂] and AnPPh₂ gives [HRu(CO)₃(PPh₂C₁₄H ₈)][(μ-H)₄Ru₄(CO)₁₁(AnPPh ₂)] (2). Both compounds 1 and 2 were fully characterized by spectroscopic methods and their X-ray crystal structures were determined. For 1, initial coordination of the PPh₂ functionality at the Ru atom is accompanied by cyclometalation of the anthracenyl ring to form a Ru-C σ bond together with concomitant formation of a π bond to the adjacent Ru center and loss of the furyl ligand. The formation of 2 involves the cleavage of two Ru-Ru bonds, and the making of a Ru-P bond, followed by orthometalation of the anthracenyl ring. The optical absorption and emission spectra of 1 were recorded and the results were correlated to the DFT calculations.