Electron Paramagnetic Resonance Studies of Mn(CN)5NO2− and Cr(CN)5NO3− in Dilute Single Crystals

We have studied the electron paramagnetic resonance spectra of Mn(CN)5NO2− and Cr(CN)5NO3− as dilute solutions in single crystals of various diamagnetic hosts. From these measurements, we have obtained the spectroscopic splitting factor tensor and the hyperfine tensors to the central metal atom and nitrosyl nitrogen. In the case of Cr(CN)5NO3−, we have also measured the hyperfine tensor to carbon-13 in the equatorial and axial cyanides. We have measured the quadrupole coupling constant to 55Mn in Mn(CN)5NO2−. We have attempted to construct a coherent picture of the electronic structure of the complexes from these data. This attempt has been only partly usccessful, primarily because the spectroscopic splitting factors are much nearer the free spin value than one expects on the basis of the hyperfine data.