Bonding and structural features of metal-metal bonded homo- and hetero-dinuclear complexes supported by unsaturated hydrocarbon ligands

Alkyne–alkenyl coupling at a diruthenium complex

“…[1][2][3] For instance, as two working hands compared to one single hand, dimetallic systems offer major opportunities to build and stabilize uncommon hydrocarbyl ligands via multisite bridging coordination. [4][5][6][7][8][9][10] Alkynes are useful and versatile reagents in this setting, and in particular the {M 2 Cp 2 (CO) x } scaffold (M = Fe, Ru; Cp = η 5 -C 5 H 5 ; x = 2, 3) is suitable to promote their coupling with a diversity of bridging coordinated carbon ligands, including carbonyl, 11,12 isocyanide, 13 thiocarbonyl, 14 alkylidyne 10,15,16 and alkylidene ligands, [17][18][19][20] usually via alkyne insertion into the metal-μ-carbon bond, but alternative modes are also possible. 21 The two metal coordination spheres are coordinatively and electronically saturated, therefore prior removal of one 2-electron ligand (usually, a carbon monoxide ligand) is needed to guarantee the initial η 2 -coordination of the alkyne to one metal centre, that is a preliminary, fundamental step along the coupling process.…”

Interdependent Metal–Metal Bonding and Ligand Redox-Activity in a Series of Dinuclear Macrocyclic Complexes of Iron, Cobalt, and Nickel

“…Metal–metal bonding interactions have attracted considerable attention due to their unique electronic structures and their applications in catalysis. − Examples of M–M bonded complexes are known from across the transition series, − and the development of ligand scaffolds that are designed to support multinuclear complexes has greatly expanded the variety of clusters that contain M–M bonds. ,− Detailed investigations into how these complexes store electrons in weakly interacting d-manifolds have allowed for an advanced understanding of the nature of bonding, ,,, and in more applied research, M–M bonded systems have been exploited for unique catalytic applications. ,− …”

η6-Coordinated ruthenabenzenes from three-component assembly on a diruthenium μ-allenyl scaffold

“…6,8–10 However, sandwich compounds consisting of a ruthenabenzene acting as a η 6 organometallic ligand towards a second metal centre are significantly rarer and have been prepared mainly via ring closure reaction of open pentadienyl ligands with a suitable metal fragment (Scheme 1a). 11 In principle, dinuclear complexes should be convenient platforms to build metal-coordinated metallabenzenes; 12 in fact, unsaturated hydrocarbyl ligands, when bridging coordinated, may exhibit a peculiar reactivity provided by cooperative effects typical of a bimetallic system, thus facilitating coupling reactions with small molecular fragments otherwise not viable on related monometallic species. 13 To the best of our knowledge, only a few ruthenabenzenes coordinated to a second ruthenium centre have been prepared to date starting from a poly-ruthenium framework, 14 nevertheless the reported synthetic procedures suffer from poor selectivity and a narrow scope.…”