PLATINUM(II) AND PALLADIUM(II) COMPLEXES WITH 1,2-DIHYDROBENZOXAZOL-2-YLIDENE LIGANDS AND MOLECULAR-STRUCTURE OF TRANS-BIS(1,2-DIHYDROBENZOXAZOL-2-YLIDENE) DIIODO PALLADIUM

2-Trimethylsiloxyphenyl isocyanide 1 reacts with [MCl2(NCPh)(2)] (M = Pd, Pt) to yield homoleptic tetraisocyanide complexes [M(1)(4)]Cl-2. S ubsequent hydrolysis of the Si-O bonds leads to intramolecular nucleop hilic attack at the isocyanide carbon atom with formation of homolepti c complexes with four 1,2-dihydrobenzoxazol-2-ylidene ligands [M(CN(H) C6H4-2-O)(4)]X-2 {M = Pt, X = Cl, 2; M = Pt, X = BF4, 3; M = Pd, X = C l, 4}. Double deprotonation of 4 by ammonia yields the neutral complex [Pd(CNC6H4-2-O)(2)(CN(H)C6H4-2-O)(2)] 5. Under similar conditions, Pd I2 reacts with 1 even in excess to give only the diisocyanide complex trans-[PdI2(1)(2)] 6 which upon Si-O bond cleavage yields the neutral dicarbene complex trans-bis(1,2-dihydrobenzoxazol-2-ylidene)diiodo pal ladium 7. Complex 7 was shown by X-ray crystallography to contain a pl anar tetracoordinated palladium atom and two carbenoid benzoxazole rin gs which are rotated by about 80 degrees relative to the palladium coo rdination plane. (C) 1997 Elsevier Science S.A.