Regioselective Metal Exchange Reactions in Linked Clusters

Regioselective metal exchange reactions in linked clusters, [(CO)9Co3(μ3-C)COOCH2]2 (1)
and (CO)9Co3(μ3-C)COOCH2(μ-CCH)Co2(CO)6 (2), were investigated. The reactions of 1 with
Na[M(CO)3(C5H4R)] (M = Mo, W; R = H, COCH3, COOC2H5) gave one-step or two-step
exchange products, (CO)9Co3(μ3-C)COOCH2CH2OCO(μ3-C)Co2M(CO)8(C5H4R) (3a, M = Mo,
R = H; 3b, M = Mo, R = COCH3; 3c, M = Mo, R = COOC2H5; 3d, M = W, R = H; 3e, M =
W, R = COCH3; 3f, M = W, R = COOC2H5) or [(CO)8(C5H4R)Co2M(μ3-C)COOCH2]2 (4a, M =
Mo, R = H; 4b, M = Mo, R = COCH3; 4c, M = Mo, R = COOC2H5; 4d, M = W, R = H; 4e,
M = W, R = COCH3; 4f, M = W, R = COOC2H5). The reactions of 1 with Na2[p-{M(CO)3C5H4CO}2C6H4] (M = Mo, W) gave cyclic clusters, (5a, M = Mo; 5b, M = W). Further reaction of 3e or 4e
with Na[Mo(CO)3(C5H5)] gave a two-step exchange product, (CO)8(C5H5)Co2Mo(μ3-C)COOCH2CH2OCO(μ3-C)CoMoW(CO)7(C5H5)(C5H4COCH3) (6) or [(CO)7(C5H5)(C5H4COCH3)CoMoW(μ3-C)COOCH2]2 (7). The reactions of 2 with Na[Mo(CO)3(C5H4R)] (R = H, COCH3, COOC2H5)
also gave one-step or two-step exchange products, (CO)8(C5H4R)Co2Mo(μ3-C)COOCH2(μ-CCH)Co2(CO)6 (8a, R = H; 8b, R = COCH3; 8c, R = COOC2H5) or (CO)7(C5H4R)2CoMo2(μ3-C)COOCH2(μ-CCH)Co2(CO)6 (9a, R = H; 9b, R = COCH3; 9c, R = COOC2H5). The reaction of
2 with Na2[p-{Mo(CO)3C5H4CO}2C6H4] gave a linear cluster, p-[(CO)6Co2(μ-CHC)CH2OCO(μ3-C)Co2Mo(CO)8C5H4CO]2C6H4 (10). The structures of 3a and 8a have been determined
by single-crystal X-ray diffraction.