Dinuclear Nickel(II) Complexes of an Unsymmetric “End-Off” Compartmental Ligand: Conversion of Urea into Cyanate at a Dinuclear Nickel Core

Abstract

A phenol-based “end-off” compartmental ligand, 2-[N,N-di(2-pyridylmethyl)aminomethyl]-6-{N-[2-(dimethylamino)ethyl]iminomethyl}-4-methylphenol (HL), having an iminic bidentate and an aminic tridentate chelating arms on the 2- and 6-positions of the phenolic ring, respectively, forms dinuclear nickel complexes [Ni2(L)(AcO)(NCS)2] (1), [Ni2(L)(AcO)2(MeOH)]PF6 (2), and [{Ni2(L)(OH)(MeOH)}2(CO3)](PF6)2 (3). Complex 1 crystallizes in the monoclinic space group P21/c, a = 14.165(5) A, b=15.198(4) A, c = 17.395(8) A, β = 100.62(4)°, V = 3680(2) A3, and Z = 4. The pair of Ni ions present are bridged by the phenolic oxygen of L- and an acetate group in syn−syn mode (Ni−Ni: 3.373(3) A). An isothiocyanate nitrogen atom coordinates to each Ni providing an asymmetric dinuclear core with a mixed {5/6} coordination number set. Complex 2 crystallizes in the monoclinic space group P21/c, a = 13.505(5) A, b = 12.028(4) A, c = 22.774(9) A, β = 103.78(3)°, V = 3592(2) A3, and Z = 4. It has a dinuclear core bridged by the ph...