Low-dimensional compounds containing cyano groups. XV. Preparation, crystal structure and spectral properties of three copper(II) nitrosodicyanomethanide complexes

Abstract

We describe the preparation and crystal structures of the ionic complexes [Cu(bipy)2{ONC(CN)2}]CF3SO3 (1b), [Cu(phen)2{ONC(CN)2}]PF6 (2p) and [Cu(bipy)2{ONC(CN)2}]PF6 (2b). In the complex cations [Cu(L)2{ONC(CN)2}]+ (L is 2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen)) the two molecules of bipy or phen coordinate to the copper atom through two nitrogen atoms along with the oxygen atom of the nitrosodicyanomethanide anion, ONC(CN) 2 − , to form a {CuN4O} chromophore with a distorted square pyramidal coordination sphere in (1b) and (2b) and a distorted trigonal bipyramidal geometry in (2p). The basal plane in (1b) and (2b) is formed by an oxygen atom coordinated at the Cu1–O1 distance of 1.990(2) and 2.002(2) A, respectively, and three nitrogen atoms coordinated to the copper atom at similar distances with the average of 2.01(2) and 2.00(3) A, respectively. The axial position is occupied by the fourth N atom at the longer distance of 2.222(2) and 2.185(2) A, respectively. The trifluoromethanesulfonate anion (triflate), CF3SO 3 − , in (1b) might be considered as very weakly coordinated in the opposite axial position (Cu1–O2 = 2.719(2) A). The equatorial plane in (2p) is formed by an oxygen atom coordinated at the Cu1–O1 distance of 1.975(3) A, and two nitrogen atoms from different phen molecules coordinated to the copper atom at the same distance within 2 σ with the average distance of 2.124(2) A. The axial positions are occupied by remaining two nitrogen atoms coordinated at shorter distance (average Cu–N = 1.99(3) A). The hexafluorophosphate anions, PF 6 − , in (2p) and (2b) remain uncoordinated. Besides the ionic forces, the structures of (2p) and (2b) may be stabilized by very weak C–H···F whereas the structure of (1b) by very weak C–H···F, C–H···O and C–H···N hydrogen bonds. The structural–spectral correlations are also discussed.