The cyanocarbanion (C[C(CN)2]3)2- as monodentate ligand: Synthesis, structure and magnetic properties of [Mn 2(bpym)3(tcpd)2(H2O)2] (tcpd2- = (C[C(CN)2]3)2- and bpym = 2,2′-bipyrimidine)
Abstract
One-pot reaction between MnCl2•4H2O, K 2tcpd (tcpd2- = [C10N6]2- = (C[C(CN)2]3)2- = 2-dicyanomethylene-1,1,3,3- tetracyanopropanediide anion) and 2,2′-bipyrimidine (bpym = C 8H6N4) in aqueous solution yields the new compound [Mn2(bpym)3(tcpd)2(H 2O)2] (1). The molecular structure of 1 consists of a centrosymmetrical binuclear complex which includes unprecedented unidentate tcpd ligands with two bidentate and a bis-chelate bpym units. Examination of the intermolecular distances reveals that the dinuclear units are held together by hydrogen bonds involving coordinated water molecules and two nitrile groups of the tcpd ligand, giving rise to a 2D structure overall. Variable-temperature magnetic susceptibility data show the occurrence of slight antiferromagnetic coupling (J = -0.58 cm-1) between the Mn(II) ions through bridging bpym (the exchange Hamiltonian being defined as Ĥ=- 2JŜA·ŜB). © 2005 Elsevier B.V. All rights reserved.