REACTIONS OF [CP-ASTERISK-RUOME]2 .10. SYNTHESIS, STRUCTURE, AND TRANSFORMATIONS OF [CP-ASTERISK-RU(MU-ETA-3-O(CH2)2CH=CH2)]2, AND ALKOXIDE-BRIDGED DIMER DESTABILIZED BY INTERNAL PI-COORDINATION

The Ru alkoxo complex [Cp*RuOMe]2 (1) reacts with but-3-en-1-ol below room temperature with exchange of the alkoxo group to yield the respective butenyloxy dimer [Cp*Ru(eta-3-O(CH2)2CH=CH2)]2 (2), which was characterized by an X-ray structure determination (orthorhombic space group Fdd2, Z = 8, 4 pairs of enantiomers, a = 38.936 (2) angstrom, b = 8.976 (2) angstrom, c = 15.406 (3) angstrom). In 2 the olefinic double bonds are coordinated to Ru, leading to a flattened Ru-O-Ru-O rhombus. Complex 2 shows enhanced thermal and substitutional reactivity compared to 1. On reaction with two-electron ligands L (L = PPh3, CH2=CH2, PhCH=CH2, PhC=CPh) the butenyloxy group is transformed into an allenecarboxaldehyde ligand, giving the complexes Cp*Ru(eta-3-CH2CHCH-CHO)L. Acrylic acid substitutes a methoxy group in 1, yielding Cp*Ru(eta-2-O2CCH=CH2)(eta-2-CH2=CHCOOH) (12) and, on addition of PPh3, Cp*Ru(eta-3-O2CCH=CH2)PPh3 (13).