title: Analysis of anisotropic effects in trinuclear metal carbonyl compounds by visualization of through-space NMR shielding.
abstract: Through-space NMR shieldings were calculated for trinuclear metal-carbonyl compounds [M(3)(CO)(12)] (M = Fe, Ru, Os), employing the nucleus-independent chemical shift approach. The through-space shieldings were visualized as a contour plot of iso-chemical shielding surfaces, and were applied to quantify the overall anisotropic effect of the carbonyl groups, as well as to identify the influence of the transition metal on the scopes of the corresponding anisotropy cones. The shielding surfaces show that the anisotropic effect of the carbonyl groups at equatorial positions changes depending on the metal. This effect was associated with pi-backdonation from the metal to the carbonyl groups in that position, in agreement with geometric data as well as calculated NMR parameters. Therefore, visualization of the through-space NMR shieldings of trinuclear metal-carbonyl compounds of group 8 is able to reflect the distinct arrangements of the carbonyl groups in these organometallic compounds.
authors.affiliation: Departamento de Físico-Química, Universidade Federal Fluminense, Outeiro de São João Batista, Niterói, RJ, Brazil. mtaraujo@vm.uff.br
authors.forename: Martha T
authors.initials: MT
authors.lastname: de Araujo
authors.forename: Eluzir P
authors.initials: EP
authors.lastname: Chacon
authors.forename: José W
authors.initials: JW
authors.lastname: de M Carneiro
authors.forename: Andreas
authors.initials: A
authors.lastname: Koch
authors.forename: Erich
authors.initials: E
authors.lastname: Kleinpeter
mesh_terms: D016880:Anisotropy; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D009942:Organometallic Compounds