Abstract
Reactions of Cp2W2Ir2(CO)(10) (1) with terminal arylalkynes HC=CR afford the complexes Cp2W2Ir2(mu(4)-eta(2)-HC2R)(mu-CO)(4)(CO)(4) [R = Ph (3), C6H4Me-4 (4), C6H4NO2-4 (5)] in excellent yields (56-70%). The analogous adduct with the terminal alkylalkyne HC=CBut is obtained in much lower yield (20%). An X-ray structural study of 3 reveals that the alkynes have formally inserted into the W-W bond of 1, affording clusters with a pseudooctahedral geometry. The site of reactivity in 1 is consistent with the lack of reactivity towards terminal alkynes of the isostructural and isolobally related CpWIr3(CO)(11) (2). Reaction of 1 with the buta-1,3-diynyl complex CpW(CO)(3)(C=CC=CH) (8) affords the analogous adduct Cp2W2Ir2{mu(4)-eta(2)-HC2C=CW(CO)(3)CP)(mu-CO)(4)(CO)(4) (9), shown spectroscopically to be attached via the C=CH unit rather than the WC=C group. Attempts at condensing the pendant CpW(CO)(3)C=C unit with the W2Ir2 core in 9 have proven unsuccessful. Reactions of CpWIr3(CO)(11) (2) with equimolar amounts of the tungsten acetylides CpW(CO)(3)(C=CR) (R =Ph, C6H4Me-4, C6H4NO2-4, C=CPh) afford the products Cp2W2Ir3(mu(4)-eta(2)-C2R)(mu-CO)(CO)(9) [R = Ph (11), C6H4Me-4, (12), C6H4NO2-4 (13), C=CPh (14)] in fair yields (23-45%). Product 12 has been structurally characterized, with the structural study revealing an edge-bridged tetrahedral metal core geometry and an unusual mu(4)-eta(2) (3 sigma + pi)-coordinated alkynyl ligand. The reaction corresponds to formal insertion of the alkynyltungsten reagent into an Ir-Ir linkage of 2. Reactions of 1 with these tungsten acetylides were not successful under the experimental conditions attempted, a result ascribed to steric constraints.
Original language | English |
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Pages (from-to) | 5789-5795 |
Number of pages | 7 |
Journal | Organometallics |
Volume | 17 |
Issue number | 26 |
DOIs | |
Publication status | Published - 21 Dec 1998 |