E. Rosenberg et al., COMPARATIVE REACTIVITY OF TRIRUTHENIUM AND TRIOSMIUM MU(3)-ETA(2)-IMIDOYLS .1. DYNAMICS AND REACTIONS WITH CARBON-MONOXIDE, PHOSPHINE, AND ISOCYANIDE, Organometallics, 16(12), 1997, pp. 2665-2673
The reactivity and ligand dynamics of the mu(3)-eta(2)-imidoyl cluster
s Ru-3(CO)(9)(mu(3)-eta(2)-RC=NR')(mu-H) (R = CH3, R' = Et 2; RR' = (C
H2)(3), 3; RR' = (CH2)(2)C(H)CH2OCH3 4, R = R' = CH3, 5) are compared
with the previously reported osmium analogs. The lowest energy dynamic
al process in these clusters is the ''windshield wiper'' motion over t
he face of the cluster whereas tripodal rotation of the carbonyl group
s on the unbridged metal atom is the fastest process in the analogous
osmium compounds. Although the structures of the phosphine and isocyan
ide substitution products reported, Ru-3(CO)(8)(mu(3)-eta(2)-RC=NR')(m
u-H)L (R = CH3, R' = CH2CH3, L = PPh3 (So), L = CNMe (12); R = R' = (C
H2)(3), L = PPh3 (9), L = CNMe (13); R = R' = CH3, L = PPh3 (10), are
identical to their osmium analogs, the pathway to their formation refl
ects the lower CO dissociation energies for ruthenium clusters and a g
reater sensitivity to the substituents on the imidoyl group. The solid
state structures of 9 and 12 are reported as well as that of s-3(CO)(
8)(mu-eta(2)-C=N(CH2)(3)(mu-H)(PPh3)(MeNC) (15). The latter illustrate
s the hemilabile nature of the mu(3)-imidoyl ligand even in phosphine-
substituted derivatives and the structural preferences of phosphine an
d isocyanide ligands in this class of clusters.