Synthesis, X-ray structure and reactivity of μ-(CF3COO)2-[Mo(N-2,6-i-Pr2-C6H3)(CHCMe2Ph)(OOCCF3)(Et2O)]2, the first Bis(trifluoroacetate) derivative of a Schrock catalyst

Reaction of Mo(N-2,6-i-Pr-2-C6H3)(CHCMeIC6H5)(OSO2CF3)(DME) (DME = 1,2-dimethoxyethane) with 2 equiv. of CF3COOK yields mu-(CF3COO)(2)-[Mo(N-2,6-i-Pr-2-C6H3)(CHCMe2Ph)(OOCCF3)(Et2O)](2) (1). Compound I crystallizes in the orthorhombic space group Pna2(1) with a = 17.2485(3), b = 17.0336(3), c = 25.4031(5) angstrom, alpha = beta = gamma = 90 degrees, V= 7463. 5(2) angstrom(3), Z = 4. In contrast to alkoxide based Schrock type initiators, I is virtually inactive in numerous metathesis reactions including ring-closing metathesis (RCM) and homo metathesis reactions, the cyclopolymerization of 1,6-heptadiynes, and even ring-opening metathesis polymerization (ROMP) of norborn-2-ene. However, addition of quinuclidine results in the in situ formation of I a (Mo(N-2,6-i-Pr-2-C6H3)(CHCMeC6H5)(OOCCF3)(2)(quinuclidine) which displays moderate activity in ROMP, cyclopolymerization of 1,6-heptadiynes and RCM. Theoretical investigations carried out on the B3LYP/LACVP* level provide substantial explanation for these findings. (c) 2006 Elsevier B.V. All rights reserved.