Reactions of triorganosilanes with tris-µ-(t-butyl isocyanide)-tris(t-butyl isocyanide)-triangulo-triplatinum: crystal structure of the complex [{Pt(CH:NBut)(SiMePh2)(CNBut)}2]

Abstract

The triplatinum compound [Pt₃(CNBu^t)₆] reacts with triorganosilanes SiR₃H [SiR₃= SiMe₃, SiEt₃, SiMe₂Ph, SiMePh₂, SiPh₃, or Si(OEt)₃] to give diplatinum complexes [{Pt(CH:NBu^t)(SiR₃)(CNBu^t)}₂], arising from insertion of an isocyanide ligand into a Pt–H bond, formed in an initial oxidative-addition step. The reaction with SiPh₃H also afforded the bis(silyl)platinum complex [Pt(SiPh₃)₂(CNBu^t)₂]. The structure of the diplatinum compounds has been established by a single-crystal X-ray diffraction study of [{Pt(CH:NBu^t)(SiMePh₂)(CNBu^t)}₂] which showed that the two platinum atoms, each in a square-planar environment, are bridged by HC:NBu^t ligands to give a six-membered ring of boat conformation. The terminal ligands are such that the silyl groups are trans to the N atoms of the central ring. The Pt–N bond is exceptionally long (2.17₃Å) and the trans-annular Pt ⋯ Pt distance of 3.05₆Å suggests little metal–metal interaction. Crystals of the title compound are monoclinic, space group P2₁/c, with Z= 4 in a unit cell of dimensions a= 11.649(4), b= 18.778(15), c= 21.825(15)Å, and β= 97.31(3)°. The structure has been solved by heavy-atom methods from 7 096 intensity data [l 2.0σ(l)] measured on a four-circle diffractometer at –50 °C, and refined to R 0.057. The compound [Pt₃(CNBu^t)₆] reacts with GeMe₃H to give an analogous diplatinum complex [{Pt(CH:NBu^t)(GeMe₃)(CNBu^t)}₂].