A low-coordinate platinum(0)-germylene for E-H bond activation and catalytic hydrodehalogenation.

Pairing transition metals and heavier tetrylenes (Si, Ge, Sn, Pb) holds great potential for cooperative bond activation and catalysis. In this work, we investigate the reactivity of a low-coordinate Pt(0)/Ge(II) system that emerges from the reaction between the monoligated platinum(0) precursor [(PMeAr)Pt(olefin)] with germylene dimer [ArGeCl] (where Ar = CH-2,6-(CH-2,6-Pr)). The resulting complex reveals ability for cooperative bond activation.

Tuning the Inorganic Core of a reduced NiGe Cluster.

Tetranuclear cores (M-E) of transition metals (M) and tetrylenes (E=Si, Ge, Sn) are key motifs in homogeneous and heterogeneous catalysis. They exhibit a continuum of M-M and E-E bonding within the inorganic core that leads to a variety of structures for which there are no specific synthetic methods. Herein, we report a series of highly reduced [NiGe] squares solely stabilized by bulky terphenyl (CH-2,6-Ar) ligands, for which we provide complementary and high-yielding syntheses.

Mechanistic Investigations on Hydrogenation, Isomerization and Hydrosilylation Reactions Mediated by a Germyl-Rhodium System.

We recently disclosed a dehydrogenative double C-H bond activation reaction in the unusual pincer-type rhodium-germyl complex [(Ar)ClGeRh] (Ar=CH-2,6-(CH-2,4,6-Me)). Herein we investigate the catalytic applications of this Rh/Ge system in several transformations, namely semihydrogenation of internal alkynes, -isomerization of olefins and hydrosilylation of alkynes. We have compared the activity and selectivity of this catalyst against other common rhodium precursors, as well as related sterically hindered rhodium complexes, being the one with the germyl fragment superior in terms of selectivity towards -isomers.

Dehydrogenative Double C-H Bond Activation in a Germylene-Rhodium Complex*.

Transition metal tetrylene complexes offer great opportunities for molecular cooperation due to the ambiphilic character of the group 14 element. Here we focus on the coordination of germylene [(Ar ) Ge :] (Ar =C H -2,6-(C H -2,4,6-Me ) ) to [RhCl(COD)] (COD=1,5-cyclooctadiene), which yields a neutral germyl complex in which the rhodium center exhibits both η - and η -coordination to two mesityl rings in an unusual pincer-type structure. Chloride abstraction from this species triggers a singular dehydrogenative double C-H bond activation across the Ge/Rh motif.

Structural Snapshots of π-Arene Bonding in a Gold Germylene Cation.

Heavier group 14 element cations exhibit a remarkable reactivity that has typically hampered their isolation. For the few available examples, the role of π-arene interactions is crucial to provide kinetic stabilization, but dynamic and structural information on those contacts is yet limited. In this study we have accessed the metalogermylenium cation [(PMe Ar )AuGe(Ar )Cl] (4 ) (Ar =C H -2,6-(C H -2,6-iPr ) ) that has been structurally characterized with three different non-coordinating counter anions.

Metal-only Lewis Pairs of Rhodium with s, p and d-Block Metals.

Metal-only Lewis pairs (MOLPs) in which the two metal fragments are solely connected by a dative M→M bond represent privileged architectures to acquire fundamental understanding of bimetallic bonding. This has important implications in many catalytic processes or supramolecular systems that rely on synergistic effects between two metals. However, a systematic experimental/computational approach on a well-defined class of compounds is lacking.

Aldehydes and ketones influence reactivity and selectivity in nickel-catalysed Suzuki-Miyaura reactions.

The energetically-favorable coordination of aldehydes and ketones - but not esters or amides - to Ni during Suzuki-Miyaura reactions can lead either to exquisite selectivity and enhanced reactivity, or to inhibition of the reaction. Aryl halides where the C-X bond is connected to the same π-system as an aldehyde or ketone undergo unexpectedly rapid oxidative addition to [Ni(COD)(dppf)] (), and are selectively cross-coupled during competition reactions. When aldehydes and ketones are present in the form of exogenous additives, the cross-coupling reaction is inhibited to an extent that depends on the strength of the coordination of the pendant carbonyl group to Ni.

Reactivity of a gold(i)/platinum(0) frustrated Lewis pair with germanium and tin dihalides.

The reactivity of germanium and tin dichlorides with a transition metal-only frustrated Lewis pair based on Au(i) and Pt(0) compounds bearing bulky phosphine ligands is described in this work. We have examined both the reactivity of tetrylene dihalides towards the individual components of the metallic pair, as well as under metal/metal cooperative conditions. These studies allowed us to isolate several uncommon homo- and heterometallic structures.

Preparation of Tris-Heteroleptic Iridium(III) Complexes Containing a Cyclometalated Aryl-N-Heterocyclic Carbene Ligand.

A new class of phosphorescent tris-heteroleptic iridium(III) complexes has been discovered. The addition of PhMeImAgI (PhMeIm = 1-phenyl-3-methylimidazolylidene) to the dimer [Ir(μ-Cl)(COD)] (1; COD = 1,5-cyclooctadiene) affords IrCl(COD)(PhMeIm) (2), which reacts with 1-phenylisoquinoline, 2-phenylpyridine, and 2-(2,4-difluorophenyl)pyridine to give the respective dimers [Ir(μ-Cl){κ- C, C-(CH-ImMe)}{κ- C, N-(CH-isoqui)}] (3), [Ir(μ-Cl){κ- C, C-(CH-ImMe)}{κ- C, N-(CH-py)}] (4), and [Ir(μ-Cl){κ- C, C-(CH-ImMe)}{κ- C, N-(CFH-py)}] (5), as a result of the N-heterocyclic carbene (NHC)- and N-heterocycle-supported o-CH bond activation of the aryl substituents and the hydrogenation of a C-C double bond of the coordinated diene. In solution, these dimers exist as a mixture of isomers a (Im trans to N) and b (Im trans to Cl), which lie in a dynamic equilibrium.

Pyrazolylamidino ligands from coupling of acetonitrile and pyrazoles: a systematic study.

Mixed pyrazole-acetonitrile complexes, both neutral fac-[ReBr(CO)3(NCMe)(pz*H)] (pz*H = pzH, pyrazole; dmpzH, 3,5-dimethylpyrazole; or indzH, indazole) and cationic fac-[Re(CO)3(NCMe)(pz*H)2]A (A = BF4, ClO4, or OTf), are described. Their role as the only starting products to obtain final pyrazolylamidino complexes fac-[ReBr(CO)3(NH═C(Me)pz*-κ(2)N,N)] and fac-[Re(CO)3(pz*H)(NH═C(Me)pz*-κ(2)N,N)]A, respectively, is examined. Other products involved in the processes, such as fac-[ReBr(CO)3(pz*H)2], fac-[Re(CO)3(NCMe)(NH═C(Me)pz*-κ(2)N,N)]A, and fac-[Re(CO)3(pz*H)2(OTf)] are also described.