Hydrocarbyl Ligand Transformations on Heterobimetallic Complexes

Coupling of Allenes with μ‐Alkylidyne Ligands in Diiron Complexes: Synthesis of Novel Bridging Thio‐ and Aminobutadienylidene Complexes

“…By contrast, protonation of the aminobutadienylidene complexes takes place at the terminal carbon of the C 4 chain and transforms the bridging frame into a stable vinyliminium ligand. Once again, these reactions evidence the role of the rather flexible dinuclear frame Fe 2 (CO) 2 Cp 2 in supporting transformations of the bridging ligand, in that they are accompanied and sustained by proper changes in the coordination mode or in the configuration of the ancillary ligands (cis-trans isomerizations).…”

“…Then, investigations were extended to the thiocarbyne complex [Fe 2 {µ-CS(Me)}(µ-CO)(CO) 2 (2) in order to compare the reactivity of the thio-and aminoalkylidyne ligands and evidence the possible influence of the heteroatom (S or N). The reactions of 2 with allenes (H 2 C=C=CRЈRЈЈ), under analogous conditions to those described for the aminocarbyne complexes, result in the formation of the neutral complexes 4a-c (Scheme 5), which have been purified by chromatography on alumina and characterized by spectroscopy.…”

“…These reactions take advantage of specific organic substrate activation due to multisite coordination and of reactivity patterns which are distinct from those of corresponding species in mononuclear complexes. [2] Within this field, the coupling of bridging alkylidyne (µ-CR) and alkylidene (µ-CR 2 ) ligands with alkynes [3] and, to a lesser extent with alkenes, [4] is well known to provide excellent routes to the synthesis of bridging C 3 hydrocarbyl ligands.…”

“…In particular, there are few examples of coupling reactions between allenes and bridging alkylidynes and alkylidenes. These include the reactions of allenes with the µ-methylidene complexes [NiW(µ-CH 2 )(µ-CO)(CO) 2 (Cp)(Cp*)], [6] [Ru 2 (µ-CH 2 )(µ-CO)(CO)(MeCN)-(Cp 2 )], [7] [RhM(CO) 2 (µ-CH 2 )(dppm) 2 ] + (M = Ru, Os) [8] and [Fe 2 (µ-CH 2 )(CO) 8 ], [3e] which lead to the formation of trimethylenemethane species (Scheme 1, I), and the reactions of the bridging methylidyne complexes [L 2 W(µ-CSiMe 3 )] 2 (L = Me 3 SiCH 2 , iPrO) [9] with allenes, which afford a related C 4 allylalkylidene fragment (Scheme 1, II).…”

Facile CH Bond Formation by Reductive Elimination at a Dinuclear Metal Site

“…[3, 4] The nature of these processes on metal surfaces and at polynuclear metal centers is certainly more complex and is not as well understood, but it is certainly of no less importance. [5][6][7] Multicenter metal-based transformations of hydrocarbons are believed to be important in heterogeneous catalytic hydrogenations, [8] petroleum reforming, [9] and Fischer-Tropsch chemistry. [10] There are strong similarities between the reductive elimination of C À H bonds and the reductive elimination of the HÀH bond to form H 2 .…”