Isocyanide ligation at ruthenium(II) complexes with chelating tertiary amine and porphyrin ligands. Structural and electrochemical studies

Abstract

Reaction of [Ru(Me 3tacn)(PMe 3) 2(O 2CCF 3)]PF 6 with one equivalent of t-BuNC or 4-cyano-1-isocyano-2,6-diisopropylbenzene (L′) in refluxing 1,2-dichloroethane gave [Ru(Me 3tacn)(PMe 3)(t-BuNC)(O 2CCF 3)]PF 6 (1)·PF 6 and [Ru(Me 3tacn)(PMe 3)(L′)(O 2CCF 3)]PF 6 (3)·PF 6, respectively. In the presence of zinc amalgam, reactions of [Ru(Me 3tacn)(H 2O) 2(O 2CCF 3)](OTf) 2, trans-[Ru(16-TMC)Cl 2]Cl and cis-[Ru(2,2,2-tet-Me 6)Cl 2]PF 6 with an excess of t-BuNC in 1,2-dichloroethane, followed by anion metathesis, afforded [Ru(Me 3tacn)(t-BuNC) 2(O 2CCF 3)]PF 6 (2)·PF 6, trans-[Ru(16-TMC)(t-BuNC) 2](ClO 4) 2 (4)·(ClO 4) 2 and cis-[Ru(2,2,2-tet-Me 6)(t-BuNC) 2](PF 6) 2 (5)·(PF 6) 2, respectively. Treatment of [Ru(Por)(CO)(MeOH)] (Por=TPP, 4-MeO-TPP or 4-F-TPP) with an excess of t-BuNC or L′ gave [Ru(TPP)(t-BuNC) 2] (6) or [Ru(4-MeO-TPP)(L′) 2] (7) and [Ru(4-F-TPP)(L′) 2] (8), respectively. 1·PF 6-5·(PF 6) 2 display a quasi-reversible Ru(III/II) couple at potentials ranging from +0.65 to +1.42 V vs. FeCp 2 +/0. The E 1/2(Ru III/II) of 5·(PF 6) 2 (+1.42 V vs. FeCp 2 +/0) is notably high compared with that of 4·(ClO 4) 2 (+0.65 V), reflecting the strong π-back-bonding in the cis-bis(tert-butyl isocyanide)ruthenium(II) complex. Irrespective of the overall charge, the cationic complex 4 and the neutral complexes 6-8 all exhibit a virtually linear RNC-Ru-CNR moiety. © 2000 Elsevier Science S.A.