Template Synthesis of Platinum Complexes with Benzoxazolin-2-ylidene Ligands

2-(Trimethylsiloxy)phenyl isocyanide (1) reacted with cis-[PtCl2(PPh3)(2)] (2), and subsequent hydrolysis of the O-SiMe3 bond yielded trans- [Pt(benzoxazolin-2-ylidene)Cl(PPh3)(2)]Cl (3). Reaction of dinuclear complex [Pt(mu-Cl)(dppe)](2)(CF3-SO3)(2) (4) [dppe = 1,2-bis(diphenylphosphanyl) ethane] with two equivalents of 1 did not yield the expected monocarbene complex but the dicarbene complex [Pt(benzoxazolinato-2-ylidene)(benzoxazolin-2-ylidene)(dppe)](CF3SO3) (5). A single-crystal X-ray diffraction study showed that complex 5 contains one deprotonated and one protonated heterocarbene ligand. The two carbene ligands are linked by a N-H center dot center dot center dot N hydrogen bond which forces them in a sterically unfavored coplanar arrangement. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)