BIS(MU-PYRIDAZINE)-BIS[(2-CYANOGUANIDINE) COPPER(I)] CATION - A MOLECULE CONTAINING 2 COORDINATIVELY UNSATURATED COPPER(I) CENTERS

2-Cyanoguanidine [(NH2)2CNCN (cnge)] stabilises co-ordinatively unsaturated copper(I) in bis(mu-pyridazine)-bis[(2-cyanoguanidine)copper(I)] tetrafluoroborate 1, which has been structurally characterised by single-crystal X-ray diffraction analysis [triclinic, space group P1BAR, a = 754.8(2), b = 971.3(2), c = 937.2(2) pm, alpha = 118.94(2), beta = 94.72(2), gamma = 107.44(2)-degrees]. The cation in 1 contains two trigonal-planar copper(I) atoms bridged by two pyridazine (pydz) molecules and terminally co-ordinated by a cnge molecule. It acts as a receptor molecule binding a further pydz to form tris(mu-pyridazine)-bis[(2-cyanoguanidine)copper(I)] tetrafluoroborate 2. The structure of 2 was also determined [monoclinic, space group C2/c, a = 2229.3(7), b = 850.0(3), c = 1568.5(3) pm, beta = 99.13(2)-degrees]. It contains two distorted-tetrahedral copper(I) atoms bridged by three pydz molecules and terminally co-ordinated by a cnge molecule. Thermogravimetric analysis of 2 showed that heating removes the third bridging pydz molecule to regenerate 1; this behaviour is ascribed to the unusually high stability of the co-ordinatively unsaturated copper(I) moiety in 1.