unsymmetrical diruthenium amidinates in which the μ2-amidinate bridge is perpendicular to the Ru-Ru axis : Synthesis and reactions of derivatives of [(η5-C5Me5)Ru(μ-amidinate)Ru(η5-C5H5)]+

New diruthenium complexes, of which two organoruthenium species, (η 5 -C 5 Me 5 )Ru and (η 5 -C 5 H 5 )Ru, are linked by a bridging amidinate ligand, were synthesized and characterized. Treatment of (η 5 -C 5 Me 5 )Ru(η-amidinate)[amidinate: i PrN=C(Me)N i Pr] with [(η 5 -C 5 H 5 )Ru-(η-NCMe) 3 ] + PF 6 - resulted in formation of a cationic diruthenium amidinate, [(η 5 -C 5 Me 5 )-Ru(μ 2 -amidinate)Ru(η 5 -C5H5)(η-NCMe)]+PF6- (4), which was converted to (η 5 -C 5 Me 5 )Ru-(μ 2 -amidinate)Ru(η 5 -C5H5)X [X = Cl (5a), Br (5b)] by treatment with the halide anion. The molecular structures and spectroscopic data of 4 and 5a including their solution dynamics are compared with their bis-pentamethylcyclopentadienyl homologues, [(η 5 -C 5 Me 5 )Ru-(μ 2 -amidinate)Ru(η 5 -C5Me5)(η 7 -NCMe)] + PF 6 - and (η 5 -C5Me5)Ru(μ 2 -amidinate)Ru(η 5 -C5H5)Cl. Treatment of 5a with TIBF 4 produced a diruthenium complex, [(η 5 -C 5 Me 5 )Ru(μ 2 -amidinate)-Ru(η 5 -C 5 H 5 )] + BF 4 - (6), bearing 34 valence electrons, which was isolated and characterized by spectroscopy. The coordinatively unsaturated nature of 6 was evidenced by facile reactions with two-electron-donor ligands, NCMe, PMe 3 , t BUNC, and CO. The coordinatively unsaturated complex 6 and its precursors, 4 and 5, exhibited catalytic activity toward cyclization of N-tosyl-N-allyltrichloroacetamide, which was compared with the corresponding bis-pentamethylcyclopentadienyl homologues.