EPR Insensitivity of the Metal‐Nitrosyl Spin‐Bearing Moiety in Complexes [L
<sub>
<i>n</i>
</sub>
Ru
<sup>II</sup>
‐NO
<sup>·</sup>
]
<sup>
<i>k</i>
</sup>
作者:Stéphanie Frantz、Biprajit Sarkar、Monika Sieger、Wolfgang Kaim、Federico Roncaroli、José A. Olabe、Stanislav Záliš
DOI:10.1002/ejic.200400042
日期:2004.7
AbstractA survey of 18 paramagnetic species [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, phosphanes, carbonyl, cyclopentadienides, halides, hydride, hydroxide, thiocyanate or cyanide: g1 = 2.015 ± 0.02, g2 = 1.990 ± 0.015, g3 = 1.892 ± 0.03, gav = 1.968 ± 0.02, Δg = g1 − g3 = 0.122 ± 0.037, A2(14N) = 3.3 ± 0.5 mT. This rather small variability, smaller still if the organometallic compounds are excluded, differs from the wider range of EPR data reported for nitrosyliron species with S = 1/2; apparently, the RuNO}7 configuration involves a rather invariant and relatively covalent metal−NO interaction. DFT calculations were employed for [(NC)5Ru(NO)]3− to reproduce the EPR data, to evaluate the spin distribution (58% spin density on NO), and to reveal structural changes on reduction such as the Ru−N−O bending and Ru−NO bond lengthening. In addition, the possibility of staggered and eclipsed conformations is discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)