Solid-state B NMR studies of coinage metal complexes containing a phosphine substituted diboraanthracene ligand.

Transition metal interactions with Lewis acids (M → Z linkages) are fundamentally interesting and practically important. The most common Z-type ligands contain boron, which contains an NMR active B nucleus. We measured solid-state B{H} NMR spectra of copper, silver, and gold complexes containing a phosphine substituted 9,10-diboraanthracene ligand (BP) that contain planar boron centers and weak M → BR linkages ([(BP)M][BAr] (M = Cu (1), Ag (2), Au (3)) characterized by large quadrupolar coupling () values (4.4-4.7 MHz) and large span () values (93-139 ppm). However, the solid-state B{H} NMR spectrum of K[Au(BP)] (4), which contains tetrahedral borons, is narrow and characterized by small and values. DFT analysis of 1-4 shows that and are expected to be large for planar boron environments and small for tetrahedral boron, and that the presence of a M → BR linkage relates to the reduction in and B NMR shielding properties. Thus solid-state B NMR spectroscopy contains valuable information about M → BR linkages in complexes containing the BP ligand.