A survey of 18 paramagnetic LnRu(NO)k, including seven new examples studied by in situ electrolysis, reveals a surprisingly narrow range of EPR parameters despite a wide variety of ligands such as pyridine, polypyridines, imines, amines, nitriles, phosphines, carbonyl, cyclopentadienides, halides, hydride, hydroxide, thiocyanate or cyanide: g1 = 2.015 $\pm$ 0.02, g2 = 1.990 $\pm$ 0.015, g3 = 1.892 $\pm$ 0.03, gav = 1.968 $\pm$ 0.02, Dg = g1 - g3 = 0.122 $\pm$ 0.037, A2(14N) = 3.3 $\pm$ 0.5 mT. This rather small variability, smaller still if the organometallic compds. are excluded, differs from the wider range of EPR data reported for nitrosyliron species with S = 1/2; apparently, the RuNO7 configuration involves a rather invariant and relatively covalent metal-NO interaction. DFT calcns. were employed for (NC)5Ru(NO)3- to reproduce the EPR data, to evaluate the spin distribution (58\% spin d. on NO), and to reveal structural changes on redn. such as the Ru-N-O bending and Ru-NO bond lengthening. The possibility of staggered and eclipsed conformations is discussed. on SciFinder(R)
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