Coupling of terminal alkynes by RuHXL2 (X=Cl or N(SiMe3)2, L=PiPr3)

Catalytic 2,3,4-hexatriene formation by terminal alkyne coupling at calcium

“…16 For completely symmetric bridging, containing no p-bonding component, the C a -C b bond should lie perpendicular to the metal-metal vector (y = f), while a side-on p-interaction would be evidenced by values of f and y of 901 and 1801, respectively (y À f = 901). Examination of the relevant angles within the structure of 4, in (9). Symmetry operations to generate equivalent positions #1 Àx + 1, Ày + 1, Àz + 1, #2 Àx + 1, Ày, Àz + 2.…”

“…2 Although the E or Z stereochemistry of compound 2 could not be determined unequivocally it was evident that compound 1 had effected a coupling of two terminal alkynes. 3 Whilst the catalytic dimerisation of terminal alkynes by electron-rich transition metals has occasionally been observed to lead to butatriene derivatives (E/Z)-RCHQCQCQCHR, [4][5][6][7][8][9] in most cases a mixture of 1,3-and 1,4-disubstituted butenynes, RCRCC(R)QCH 2 and (E/Z)-RCRCCHQCHR, is formed. 10 In the current instance, however, it is apparent that the coupling promoted by the calcium species 1 is only superficially related to these precedents due to the lack of variable oxidation states for calcium and the inability of the alkaline earth elements to support vinylidene-type ligands.…”

Solvent and phosphine dependency in the reaction of cis-RuCl2(P–P)2 (P–P=dppm or dppe) with terminal alkynes

“…As several related butenynyl complexes [8,9,[16][17][18][19][20][21] have been proposed as intermediates in the catalytic dimerisation of alkynes, we were intrigued to discover if 3a could promote the dimerisation of PhC"CH [22]. This indeed proved to be the case.…”

Catalytic Transformations of Alkynes via Ruthenium Vinylidene and Allenylidene Intermediates

“…[58] [(η 5 -C9H7)Ru(PPh3)2CCPh],[59] [RuCl2(PCy3)2=CHPh][60] and RuHXL2 [X = Cl or N(SiMe3)2, L = Pi-Pr3] [61]. The stereoselectivity of the dimerization process can be modulated by changing the nature of the ligands in the catalysts.…”