Electron Spin Resonance and Optical Absorption of K3[Cr(CN)5 NO]· H2O

Electron spin resonance of a water solution and of the pure powder of K3[Cr(CN)5NO]·H2O reveal a single sharp resonance line at room temperature. The water solution resonance gives a Cr53 hyperfine structure which is further split by a ``superhyperfine'' structure due to the nitrogen in the NO ligand. From the electron spin resonance the Cr1+ ion appears to be in a spin quenched (dε5) orbital singlet ground state. The optical absorption data allows the determination of the splittings of the d levels in concordance with the ESR spectrum.