Some ruthenium complexes containing cyanocarbon ligands: syntheses, structures and extent of electronic communication in binuclear systems

Abstract

The preparation of several ruthenium complexes containing cyanocarbon anions is reported. Deprotonation (KOBut) of [Ru(NCCH2CN)(PPh3)2Cp]PF6 (1) gives Ru{N=C=CH(CN)}(PPh3)2Cp (2), which adds a second [Ru(PPh3)2Cp]+ unit to give [{Ru(PPh3)2Cp}2(μ-NCCHCN)]+ (3). Attempted deprotonation of the latter to give the μ-NCCCN complex was unsuccessful. Similar chemistry with tricyanomethanide anion gives Ru{N=C=C(CN)2}(PPh3)2Cp (4) and [{Ru(PPh3)2Cp}2{μ-NCC(CN)CN}]PF6 (5), and with pentacyanopropenide, Ru{N=C=C(CN)C(CN)C(CN)2}(PPh3)2Cp (6) and [{Ru(PPh3)2Cp}2{μ-NCC(CN)C(CN)C(CN)CN}]PF6 (7). The Ru(dppe)Cp* analogues of 6 and 7 (8 and 9) were also prepared. Thermolysis of 6 (refluxing toluene, 12 h) results in loss of PPh3 and formation of the binuclear cyclic complex {Ru(PPh3)Cp[μ-N=C={C(CN)=C(CN)2}CN]}2 (10). The solid-state structures of 2–4 and 8–10 have been determined and the nature of the isomers shown to be present in solutions of the binuclear cations 7 and 9 by NMR studies has been probed using Hartree–Fock and density functional theory.