Crystal structures of azine derivatives of (eta(5)-acylcyclopentadienyl)dicarbonylnitrosylchromium and unequivocal assignments of C(2,5) and C(3,4) on the cyclopentadienyl ring of azine derivatives of (eta(5)-acylcyclopentadienyl)dicarbonylnitrosylchromium, (eta(5)-acylcyclopentadienyl)tricarbonylmethylmolybdenum, and (eta(5)-acylcyclopentadienyl)tricarbonylmethyltungsten in C-13 NMR spectra

摘要

Azine derivatives-(4), (5), (12), (13)-of (eta(5)-C5H4CHO)Cr(CO)(2)(NO) (2), (eta(5)-C5H4COCH3)Cr(CO)(2)(NO) (3), (eta(5)- C5H4CHO)W(CO)(3)(CH3) (10), and (eta(5)-C5H4COCH3)W(CO)(3)(CH3) (11) were obtained from condensation reaction of hydrazine with each corresponding carbonyl group. The structures of 4 and 5 were determined by X-ray diffraction studies. The chemical shifts of the C(2)-C(5) carbon atoms of 4, 5, 12, and 13 have been assigned using two-dimensional HETCOR NMR spectroscopy. We observed that C(2,5) resonate at a lower field than C(3,4) in [(CO)(2)(NO)Cr(eta(5)-C5H4CR=N-)](2) (R = H, 4; R = CH3, 5), whereas C(3,4) resonate at a lower field than C(2,5) in [(CO)(3)(CH3)W(eta(5)-C5H4CR=N-)](2) (R = H, 12; R = CH3, 13). The correlation between the magnitudes of nonplanarity of Cp-exocyclic carbon to pi-acceptor substituents and the twist angle of NO to Cp-exocyclic carbon are discussed. The electron density distribution in the cyclopentadienyl ring is discussed on the basis of C-13 NMR data and those of 4 and 5 are compared with calculations using the density functional B3LYP exchange-correlation method. (C) 2015 Elsevier Ltd. All rights reserved.