Interconversion and ligand dependence in mononuclear and dinuclear cobalt(II) helicate complexes of 2,2′: 6′,2″: 6″,2‴:6‴,2â�—-quinquepyridines; crystal and molecular structure of aqua(methanol)[4′,4‴-bis(4-chlorophenyl)-2,2′:6′,2″:6″,2‴:6‴,2â�—-quinquepyridine]cobalt(II) bis(hexafluorophosphate)

Abstract

The crystal and molecular structure of [Co(cp₂qpy)(MeOH)(H₂O)][PF₆]₂(cp₂qpy = 4′,4‴-bis(4-chlorophenyl)-2,2′:6′,2″:6″,2‴:6‴,2â�—-quinquepyridine reveal the cation to be a mono-helical seven-coordinate species [P2₁/a, a= 17.441(4), b= 11.765(4), c= 20.402(6)å, β= 105.24(2)°] unlike 2,2′:6′,2″: 6″,2‴ :6‴,2‴ quinquepyridine (qpy), which forms a double-helical 2:2 complex with cobalt(II), [Co₂(qpy)₂(OAc)]³⁺; in acetonitrile solution the qpy and cp₂qpy complexes give rise to common mononuclear species.