Towards co-operative reactivity in conjoint classical-organometallic heterometallic complexes: the co-ordination chemistry of novel ligands with triphenylphosphine and bis(pyridylethyl)amine or triazacyclononane domains

Li, Ti(III), and Ti(IV) Trisamidotriazacyclononane Complexes. Syntheses, Reactivity, and Structures

“…Despite the extensive study of transition metal complexes of polyaza macrocyclic ligands bearing functionalized pendant arms, − [M{1,4,7-(o-NH-benzyl) 3 tacn}] (M = Fe, Co, Mn) are the sole reported examples of trisamido-tacn metal derivatives − Aiming to synthesize a ligand able to protect and direct the reactivity of metal centers through a new balance of bonding features, we designed a trisamido-triamine ligand precursor by introducing three Si(Me) 2 N(H)Ph pendant arms on the nitrogen atoms of tacn. We became interested in the reactivity of “encapsulated” metals where structural features and oxidation states may be dictated by the metal/ligand match and report here the syntheses of the ligand precursors and their titanium derivatives.…”

Aerobic alcohol oxidation catalyzed by a new, oxygen-bridged heterometallic compound [PPh4][Ru(N)Me2(μ2-O)2Pd((−)-sparteine)]

“…We have previously prepared heterobimetallic and heterotrimetallic with bridging oxo or sulfido groups through specific bridge-building reactions such as the reaction of organoosmium(VI) and organoruthenium(VI) chloro compounds [N(n-Bu) 4 ][M(N)R 2 Cl 2 ] with Ag 2 CrO 4 [4], AgReO 4 [5], or K 2 WS 4 [6]. The ruthenium compounds [N(n-Bu) 4 ][Ru(N)Me 2 Cl 2 ] also react with (trimethylsilyl)sulfido compounds M 0 (SSiMe 3 ) 2 L 2 (M 0 = Ni, Pd, Pt; L 2 = dppe, COD) to form the trimetallic species {Ru(N)Me 2 }(l 3 -S) 3 {M 0 L 2 } [7,8]. These compounds contain coordinately unsaturated metals and some of them are active for the aerobic oxidation of alcohols.…”

“…Several enzymes for oxidation reactions demonstrate this with active sites that contain and use multiple metal centers [1], and binuclear compound of iron and copper can model the oxidation reactions of enzymes [2]. The interaction between metal centers can also impede catalysis at a single metal center as it does in the oxidation of styrene with O 2 by trans-[IrCl(CO)(L-M 0 ) 2 ] [3]. Most synthetic heterometallic inorganic or organometallic compounds are poor catalysts for oxidation and other reactions because they are either coordinatively saturated and lack a site for substrate binding, or because they are not robust to the reaction conditions.…”

Coordination Studies of a New Unsymmetrical κ4-PNN‘N‘ ‘-Tetradentate Ligand: Stepwise Formation and Structural Characterization

“…We recently described a new Schiff base ligand and its coordination chemistry with a PNSe donor set combination 22a,22b,, combinations are considerably less well documented. This dearth of examples prompted us to seek a simple route to a novel PN 3 tetradentate ligand in which all three N donor centers are different.…”