Preparation and structure elucidation of novel organoruthenium amidinates bearing η4-diene ligands

Abstract A series of novel ruthenium amidinate complexes bearing η 4 -cyclooctadiene (COD) or η 4 -norbornadiene (NBD) ligand was prepared, and their structures were elucidated by spectroscopy and crystallography. A disilver amidinate, Ag 2 {μ 2 ,η-PhNC(H)NPh} 2 , was treated with either (η 4 -COD)Ru(MeCN) 2 Cl 2 or (η 4 -NBD)Ru(pyridine) 2 Cl 2 to form the corresponding bisamidinate complex, (η 4 -COD)Ru{η 2 -PhNC(H)NPh} 2 ( 5a ) or (η 4 -NBD)Ru{η 2 -PhNC(H)NPh} 2 ( 5a ′), respectively, in moderate to good yield. Alternatively, (η 4 -COD)Ru{η 2 - i PrNC(Me)N i Pr} 2 ( 5b ) or (η 4 -NBD)Ru{η 2 - i PrNC(Me)N i Pr} 2 ( 5b ′) was synthesized by reaction of [(η 4 -COD)RuCl 2 ] n or (η 4 -NBD)Ru(pyridine) 2 Cl 2 with Li{ i PrNC(Me)N i Pr}. Careful treatment of (η 4 -NBD)Ru(pyridine) 2 Cl 2 with one equivalent of Li{ i PrNC(Me)N i Pr} resulted in the formation of a monoamidinate complex, (η 4 -NBD)Ru{η 2 - i PrNC(Me)N i Pr}(pyridine)Br ( 6 ) as a good precursor for a mixed amidinate complex, (η 4 -NBD)Ru{η 2 - i PrNC(Me)N i Pr}{η 2 -PhNC(H)NPh} ( 5c ′), which was obtained by the reaction of 6 with Ag 2 {μ 2 ,η-PhNC(H)NPh} 2 . Crystal structures of these complexes revealed the octahedral arrangement of the ligands.