Crystal structures of (η5-C5H4COC6H5)Cr(NO)2(X) (X = Cl, I), and unequivocal assignments of C(2,5) and C(3,4) on the cyclopentadienyl ring of dicarbonyl(η5-cyclopentadienyl)nitrosylchromium, (η5-cyclopentadienyl)halodinitrosylchromium (halo = Cl, Br, I), bis(η5-cyclopentadienyl)iron, and tricarbonyl(η5-cyclopentadienyl)methyltungsten bearing a carbonyl substituent in 13C NMR spectra

Abstract

Metallocenyl ketones (η5-C5H4COC6H5)Cr(NO)2(X) (X = Cl, 3b; X = I, 5b), (η5-C5H5)Fe[(η5-C5H4)CO(η5-C5H5)]Cr(NO)2(X)(X = Cl, 3c; X = I, 5c), and (η5-C5H5)Fe[(η5-C5H4)CO(η5-C5H5)]W(CO)3(CH3) 6c are synthesized. The structures of 3b and 5b are determined by X-ray diffraction studies. The exocyclic carbon of 5b bends toward the Cr atom with a θ value of 3.46°. The correlation between the magnitudes of nonplanarity of Cp-exocyclic carbon to π-acceptor carbonyl substituents and the twist angle of NO to Cp-exocyclic carbon are discussed. Based on the 2D HETCOR, C(2,5) resonating at a lower field than C(3,4) on the Cp(Cr) ring whereas C(3,4) resonating at a lower field than C(2,5) on the Cp(Fe) and the Cp(W) ring are revealed. The hypothesis to elucidate these data assignments has been proposed. The electron density distribution in the cyclopentadienyl ring has been discussed on the basis of 13C NMR data and compared with calculations using the density functional B3LYP exchange–correlation method for those with X-ray diffraction studies.