Acetylide ions, -shifts

Ab initio calculations at the HF/6-31G level have been used to explore energy changes, structural variation, and electron density shifts during jr-face selective addition of substituted acetylide ions to cyclohexanone and cyclohexanethione. Charge polarization of the jr-bond on approach of the nucleophile is such that the carbonyl carbon becomes considerably electron deficient for most of the reaction path (and may... 

The solid-state emission of the acetylide complexes 92a, 92b, 93a, and 93b occurs at 490, 521, 538, and 539 nm, respectively. The emission energy shows a red shift from the dimer to the trimer but is not sensitive to the methoxy substituent on the phenylacetylide ligand. In view of this, together with the large Stokes shifts observed, the excited state has been assigned to be [(d6t) (po) ] in origin. The photochemical properties of these gold(I) acetylides have also been studied. For example, the phosphorescent state of 93a has been found to be quenched by the electron acceptor 4-methoxycarbonyl-A -methylpyridinium ion. 

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