Binuclear complexes of ruthenium with diphosphines and bridging benzene-1,2-diamide. X-Ray crystal structure of [Ru2{µ-1,2-(NH)2C6H4}{µ-(Ph2P)2CH2}(CO)2(PPh3)2]·C6H5Me

Abstract

The binuclear complex [Ru₂{µ-1,2-(NH)₂C₆H₄}(CO)₄(PPh₃)₂]1 reacts with the diphosphines (Ph₂P)₂X [X = C₂H₄(dppe), cis-C₂H₂(dppen), 1,2-C₆H₄(dppbz), C₃H₆(dppp) and C₄H₈(dppb)], in boiling toluene, to give purple solutions from which the yellow compounds [Ru₂{µ-1,2-(NH)₂C₆H₄}(CO)₃(PPh₃)(diphosphine)][dppe, 2; dppen, 3, dppbz, 4; dppp, 5; or dppb, 6 can be obtained after purification on an Al₂O₃ column and crystallization from toluene–hexane solutions. The reaction of 1 with (Ph₂P)₂CH₂(dppm), in boiling toluene or xylene, affords [Ru₂{µ-1,2-(NH)₂C₆H₄}(µ-dppm)(CO)₂(PPh₃)₂]7 as the unique product. All these new complexes can be obtained in good yields by reaction of [Ru{1,2-(NH)₂C₆H₄}(PPh₃)(diphosphine)] with [Ru(CO)₃(PPh₃)₂] in boiling mesitylene. Compound 1 also reacts with [Ru{1,2-(NH)₂C₆H₄}(PPh₃)₃] or [RuH₂(PPh₃)₄] in boiling xylene to give [Ru₂{µ-1,2-(NH)₂C₆H₄}(CO)₃(PPh₃)₃]8 which easily regenerates 1 by reaction with CO. An excess of diphosphine (except for dppm) in the reaction with 1 produced the mononuclear complexes [Ru{1,2-(NH)₂C₆H₄}(CO)(diphosphine)] and [Ru(CO)₂(PPh₃)(diphosphine)] and for the reaction with dppb the complexes [Ru₂{µ-1,2-(NH)₂C₆H₄}(CO)₃(dppb-P)(dppb-PP′)]9, [Ru₂{µ-1,2-(NH)₂C₆H₄}(µ-dppb)(CO)₂(PPh₃)₂]10, [Ru₂{µ-1,2-(NH)₂C₆H₄}(CO)₂(dppb)₂]11 and [Ru(CO)₂(dppb-P)(dppb-PP′)]12 were also detected or isolated. All complexes have been characterized by elemental analysis and by IR and NMR spectroscopy. The structure of the toluene solvate of 7 has been determined by X-ray diffraction methods: monoclinic, space group P2₁/n, with a= 18.563(8), b= 21.066(9), c= 17.936(7)Å, β= 110.47(2)° and Z= 4. The structure was solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least squares to R= 0.0524 for 6679 observed reflections. The two Ru atoms are doubly bridged by the nitrogen atoms of the 1,2-diimine ligand with a short Ru–Ru separation, 2.562(1)Å, consistent with a metal–metal bond.