166989-59-9Relevant academic research and scientific papers
Os(CO)4(η2-C2Me2)-promoted coupling of alkynes and CO: Formation of (η4-C4Me2R2CO)Os(CO)3 (R = Me, Et, nPr) and catalytic activity of (η4-C4R4CO)Os(CO)3 (R = Me, Ph)
Washington, John,McDonald, Robert,Takats, Josef,Menashe, Naim,Reshef, Dvora,Shvo, Youval
, p. 3996 - 4003 (2008/10/09)
Low-temperature photolysis of Os(CO)5 in the presence of excess 2-butyne gives Os(CO)4-(η2-C2Me2) (1) in moderate yield. Complex 1 undergoes facile alkyne-CO coupling with an additional alkyne ligand under mild thermal activation to give the cyclopentadienone-containing species (η4-C4Me2R2CO)Os(CO)3 (R = Me (2a), Et (2d), nPr (2e)). Isolation of the alkyne-carbonyl complex is not necessary to effect the transformation; in situ generated M(CO)4(η2-C2R2) provides a convenient method for the synthesis of (η4-C4R4CO)M(CO)3 (M = Ru, Os; R = Me, Et, nPr). On the basis of these observations, the proposed mechanisms for the formation of (η4-C4R4CO)M(CO)3 complexes are discussed and evaluated. The solid-state structure of 2d was determined and compared to the tetraphenyl analogue, (η4-C4Ph4-CO)Os(CO)3 (4). Compound 2d crystallizes in the monoclinic space group P21/c with a = 8.336(1) A?, b = 15.334(2) A?, c = 12.849(2) A?, β = 108.78(2)°, Z = 4, R = 0.040, and Rw = 0.046. The use of 2a and 4 as catalyst precursors for both Tishchenko and hydrogenation reactions was investigated and compared to the analogous ruthenium complex (η4-C4Ph4-CO)Ru(CO)3.
