63Cu high resolution NMR of Cu(I) halides in aqueous solution and suspension.

概要

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In an aqueous solution, 63Cu chemical shielding order ([CuCl4]3− \simeq[CuBr4]3−<[CuI4]3−) and line widths (10 to 30 kHz) for CuX–KX systems(where X=Cl, Br, I) have been obtained. The chemical shift(−694 ppm) between [CuCl4]3− and [Cu(CN)4]3− is interpreted by the paramagnetic term which depends mainly upon a 3d-hole on a Cu(I) atom by using perturbation theory with an average excitation energy approximation. The linebroadening of Cu(I) halide complexes in aqueous solution is explained dominantly by a Cu(I) nuclear quadrupole interaction with the electric field gradient which arises from a 3d-hole on a Cu atom. For the abnormal increasing metal shielding order of [MX4](4−i)−([MCl4](4−i)−≤[MBr4](4−i)−<[MI4](4−i)−), a possibility of the heavyatom effect in the metal shielding of [CuI4]3−(649 ppm, using the lowest excitation energy of the diatomic molecule) and [CdI4]3−(1941 ppm using the lowest excitation energy of the diatomic molecule), is evaluated.