A density functional study of pseudotetrahedral metal–nitrosyl complexes

Abstract

Local and nonlocal density functional computations have been carried out to study the electronic structure and the equilibrium geometry of the isoelectronic series Cr(N0)4, Mn(N0)3 (CO), Fe(N0)2(C0)2, and Co(NO)(CO)3 and model compounds Fe(N0)2L2 (L = CI, HCN, NH3, PH3, and C2H4). The structure of Fe(NO)r(C4H6) is also described. The discussion is focused on structural modifications through a change of ligand, in particular those concerning the metal-nitrosyl conformation (linear vs. bent). Though this is a preliminary study of metal -nitrosy1 properties by OFT methods and more computations are required to analyze the mechanism of homogeneous catalysis processes, our results support the hypothesis that structural reorganization from linear to bent metal-nitrosyl plays a key role in some reactions, such as in hutadiene dimerization.

Contrasting Behavior of the Z Bonds in X–Z···Y Weak Interactions: Z = Main Group Elements Versus the Transition Metals

“…The optimized geometries show slight tilt and bend in the NO ligands from the square plane, and reasons for this observation have been discussed extensively . The Rh and Ir counterparts of the model complex M­(CN) 2 (NO) 2 Cl ( 1 ) are not considered further because of the uncertainty in electron counting arising from the large deviation in Rh–N–O bond angle (140°) in Rh­(CN) 2 (NO) 2 Cl complex and the preference for trigonal bipyramidal geometry as the global minimum for Ir­(CN) 2 (NO) 2 Cl complex.…”

“…The noninnocent nature of NO ligand is used to differentiate weak noncovalent interactions from that of strong dative bonds. The linear arrangement of NO is expected to retain as in the parent complex for noncovalent M···Y interactions with NO + configuration (NO acts as three electron donor). However, it attains a bent geometry with NO – configuration (NO becomes one electron donor) for strong M←Y dative bond, where bending in NO creates unsaturation at the metal center and encourages further electron acceptance leading to strong interaction.…”

Bond Lengths Co–C(CO), Co–N(NO) and Angles L–Co–C(CO), L–Co–N(NO) in Tetrahedral Complexes⋆

“…There is a good determine the shape of the molecular potential energy hyagreement between the results of these calculations with persurface. However, geometries as observed in the solid both the experimental gas phase structure [5] and the DFT state result from the interplay of intra-and intermolecular minimised structure [17] of Co(CO) 3 (NO) ( Table 1). Howinteractions.…”

“…For flexible organometallic species molecular ever, as already noticed in ref. [17] the computed metalϪC structure and crystal packing influence each other in a comand metalϪN distances are too short and the errors in the plex manner. [8] bond lengths are larger as for pure carbonyl compounds.…”

“…[19] [20] [15] GEHCIF [16] GEHCIF* Co(CO) 3 (NO), Co(CO) 3 (NO), DFT [17] Exp. [ tween the PϪCoϪC(CO) and the PϪCoϪN(NO) angles avoided any restraints, except for complex 5 for which DELU restraints were applied to remedy for the small re-which has not been documented before.…”