Platinum-Templated Coupling of B=N Units: Synthesis of BNBN Analogues of 1,3-Dienes and a Butatriene.

The 1:2 reaction of [μ-(dmpm)Pt(nbe)] (dmpm=bis(dimethylphosphino)methane, nbe=norbornene) with Cl BNR(SiMe ) (R=tBu, SiMe ) yields unsymmetrical (N-aminoboryl)aminoboryl Pt complexes by B-N coupling via ClSiMe elimination. A subsequent intramolecular ClSiMe elimination from the tBu-derivative leads to cyclization of the BNBN unit, forming a unique 1,3,2,4-diazadiboretidin-2-yl ligand. In contrast, the analogous reaction with Br BN(SiMe ) leads, via a twofold BrSiMe elimination, to a Pt A-frame complex bridged by a linear BNBN isostere of butatriene. Structural and computational data confirm π electron delocalization over the entire BNBN unit.