Preparation and structure elucidation of novel organoruthenium amidinates bearing eta(4)-diene ligands

A series of novel ruthenium amidinate complexes bearing eta (4)-cyclooctadi ene (COD) or eta (4)-norbornadiene (NBD) ligand was prepared, and their str uctures were elucidated by spectroscopy and crystallography. A disilver ami dinate, Ag-2{mu (2-)eta -PhNC(H)=NPh}(2) , was treated with either (eta (4) -COD)Ru(MeCN)(2)Cl-2 or (eta (4)-NBD)Ru(pyridine)(2)Cl-2 to form the corres ponding bisamidinate complex, (eta (4)-COD)Ru eta (2)-PhNC(H)=NPh}(2) (5a) or (eta (4)-NBD)Ru{eta (2)-PhNC(H)=NPh)(2) (5a'), respectively, in moderate to good yield. Alternatively, (eta (4)-COD)Ru{eta (2)-(PrNC)-Pr-i(Me)=(NPr )-Pr-i}(2) (5b) or (eta (4)-NBD)Ru(eta (2)-(PrNC)-Pr-i(Me)=(NPr)-Pr-i}(2) ( 5b') was synthesized by reaction of [(eta (4)-COD)RuCl2](n) or (eta (4)-NBD )Ru(pyridine)(2)Cl-2 with Li{(PrNC)-Pr-i(Me)=(NPr)-Pr-i}. Careful treatment of (eta (4)-NBD)Ru(pyridine)(2)Cl-2 with one equivalent of Li{(PrNC)-Pr-i( Me)=(NPr)-Pr-i}(2) resulted in the formation of a monoamidinate complex, (e ta (4)-NBD)Ru{eta (2)-(PrNC)-Pr-i(Me)=(NPr)-Pr-i}(pyridine)Br (6) as a good precursor for a mixed amidinate complex, (eta (4)-NBD)Ru{eta (2)- (PrNC)-P r-i(Me)=(NPr)-N-i}{eta (2)-PhNC(H)=NPh) (5c'), which was obtained by the re action of 6 with Ag-2{mu (2),eta -PhNC(H) NPh)(2). Crystal structures of th ese complexes revealed the octahedral arrangement of the ligands. (C) 2001 Elsevier Science B.V. All rights reserved.