Phosphine and Selenoether -Substituted Acenaphthenes and Their Transition-Metal Complexes: Structural and NMR Investigations.

A series of -substituted acenaphthene-based phosphine selenoether bidentate ligands Acenap(PrP)(SeAr) (-, Acenap = acenaphthene-5,6-diyl, Ar = Ph, mesityl, 2,4,6-trisopropylphenyl and supermesityl) were prepared. The rigid acenaphthene framework induces a forced overlap of the phosphine and selenoether lone pairs, resulting in a large magnitude of through-space coupling, ranging from 452 to 545 Hz. These rigid ligands - were used to prepare a series of selected late d-block metals, mercury, and borane complexes, which were characterized, including by multinuclear NMR and single-crystal X-ray diffraction. The Lewis acidic motifs (BH, Mo(CO), Ag, PdCl, PtCl, and HgCl) bridge the two donor atoms (P and Se) in all but one case in the solid-state structures. Where the bridging motif contained NMR-active nuclei (B, Ag, Ag, Pt, and Hg), and couplings are observed directly, in addition to the altered in the respective NMR spectra. The solution NMR data are correlated with single-crystal diffraction data, and in the case of mercury(II) complexes, they are also correlated with the solid-state NMR data and coupling deformation density calculations. The latter indicate that the through-space interaction dominates in free , while in the complex, the main coupling pathway is via the metal atom and not through the carbon framework of the acenaphthene ring system.