Copper-incorporated mono- and di-TeRu5 metal carbonyl complexes: syntheses, structures, and an unusual skeletal arrangement

Two sandwich-type Cu3Cl- or Cu-2{Te2Ru4(CO)(10)}-bridging di-TeRu5 clusters, [{TeRu5(CO)(14)}(2)Cu3Cl](2-) (1) and [{TeRu5(CO)(14)}(2)Cu-2{Te2Ru4(CO)(10)}](4-) (2), were obtained from the reaction of [TeRu5(CO)(14)](2-) with 1 equiv. of [Cu(MeCN)(4)][BF4] in CH2Cl2 or THF at 0 degrees C, respectively, depending on the solvents. The chloride-abstracted 1 was structurally characterized to have two TeRu5 cores that were linked by a Cu3Cl moiety with two Cu-Cu bonds. If the reaction was carried out in a molar ratio of 1 : 2 at 0 or 30 degrees C in CH2Cl2, the structural isomers [TeRu5(mu-CO)(2)(CO)(12)(CuMeCN)(2)] (3a) and [TeRu5(mu-CO)(3)(CO)(11)Cu-2-(MeCN)(2)] (3b) were produced, respectively, as the major product. Cluster 3a displayed a TeRu5 core with two adjacent Ru-3 triangles each capped by a mu 3-Cu(MeCN) fragment, while 3b contained a TeRu5 core with one triangle Ru-3 plane capped by a Cu-2(MeCN)(2) fragment with two Cu atoms covalently bonded. Upon heating, the isomerization of 3a into 3b proceeded to undergo an unusual skeletal arrangement of Cu(MeCN) and migration of CO, with the TeRu5 core remaining intact. An electrochemical study revealed that 3a and 3b each exhibited only one oxidation while cluster 1 had two consecutive oxidations, suggesting significant electronic communication between the two TeRu5 metal cores in 1 via the Cu3 moiety. This work describes the facile synthesis of a series of semiconducting Cu-x-bridging Te-Ru carbonyl clusters, in which the incorporation of the Cu-x fragments has significantly influenced their resulting structures, rearrangements, and electronic properties, which was further elucidated by DFT calculations.