The X-ray crystal structure and electronic properties of [Cu(bipy)2(ONO)][NO3](bipy = 2,2′-bipyridyl) at 298 and 165 K, a fluxional cis-distorted octahedral CuN4O2chromophore

The X-ray crystal structures of [Cu(bipy)2(ONO)][NO3](bipy =2,2′-bipyridyl) are reported at 298 and 165 K; significant differences occur which are consistent with a fluxional behaviour of the CuN4O2 chromophore, and enable the underlying static stereochemistry to be predicted and rationalised using the i.r. spectrum of the nitrito-group and the electronic reflectance spectrum of the CuN4O2 chromophore.