NMR Investigations on (Benzene) Chromium Tricarbonyl Oriented in a Nematic Phase

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Abstract
The NMR spectrum of (benzene) chromium tricarbonyl oriented in the nematic phase of a mixture of 50% 4-methoxybenzylidene 4-amino-α-methyl cinnamic acid-n-propyl ester and 50% anisole-p-azophenyl-n-capronate has been investigated. It has been shown that the complex has a structure in which the Cr(CO)3 group is bonded to the delocalised π-electron cloud such that the effective symmetry is 6-fold. Ratios of the interproton distances are determined. Contrary to other aromatics, the molecule is shown to orient preferentially with the benzene plane perpendicular to the direction of the magnetic field, under the assumption that the indirect H-H couplings in the complex have the same sign as in benzene. The proton chemical shift anisotropy in the compound is determined.