IR spectroscopic results, combined with earlier crystallographic and spectr
oscopic evidence on Fe and Ru nitrosyl complexes, indicate that metastable
eta(1)-O and eta(2)-NO linkage isomers are formed on low-temperature irradi
ation of the nitrosyl metalloporphyrins (OEP)Ru(NO)L (L = O-i-C5H11, SCH2CF
3); the new compounds are stable at low temperature, but revert to the grou
nd state on warming.