More than four decades ago, a complex identified as the planar homoleptic lithium nickelate “LiNiPh3(solv)3” was reported by Taube and co-workers. This and subsequent reports involving this complex have lain...

There is a continous growing interest on the design of bimetallic cooperative complexes that emerges from their potential for bond activation and catalysis, a potential that has been widely exploited...

A joint experimental/computational effort to elucidate the mechanism of dihydrogen activation by a gold(I)/platinum(0) metal-only frustrated Lewis pairs is described herein. We have also investigated the drastic effects on H2 activation derived from subtle ligand modifications. The importance of the balance between bimetallic adduct formation and complete frustration has been interrogated, providing for the first time evidence for genuine metal-only FLP reactivity in solution. The origin of a strong inverse kinetic isotopic effect has also been clarified, offering further support for the proposed bimetallic FLP-type cleavage of dihydrogen.

The reactions of LiAlH 4 as the source of LiH with complexes that contain (H)Mo≣Mo and (H)Mo≣Mo(H) cores stabilized by the coordination of bulky Ad Dipp2 ligands result in the respective coordination of one and two molecules of (thf)LiH, with the generation of complexes exhibiting one and two HLi(thf)H ligands extending across the Mo≣Mo bond (Ad Dipp2 = HC(NDipp) 2 ; Dipp = 2,6- i Pr 2 C 6 H 3 ; thf = tetrahydrofuran, C 4 H 8 O). A theoretical study reveals the formation of Mo–H–Li three-center–two-electron bonds, supplemented by the coordination of the Mo≣Mo bond to the Li ion. Attempts to construct a [Mo 2 {HLi(thf)H} 3 (Ad Dipp2 )] molecular architecture led to spontaneous trimerization and the formation of a chiral, hydride-rich Mo 6 Li 9 H 18 supramolecular organization that is robust enough to withstand the substitution of lithium-solvating molecules of tetrahydrofuran by pyridine or 4-dimethylaminopyridine.

Bimetallic motifs mediate the selective activation and functionalization of CO 2 in metalloenzymes and some recent synthetic systems. In this work, we build on the nascent concept of bimetallic frustrated Lewis pairs (FLPs) to investigate the activation and reduction of CO 2 . Using the Fe 0 fragment [(depe) 2 Fe] (depe = 1,2-bis(diethylphosphino)ethane) as base, we modify the nature of the partner Lewis acid to accomplish a divergent and highly chemoselective reactivity towards CO 2 . [Au(PMe 2 Ar)] + irreversibly dissociates CO 2 , Zn(C 6 F 5 ) 2 and B(C 6 F 5 ) 3 yield different CO 2 adducts stabilized by push-pull interactions, while Al(C 6 F 5 ) 3 leads to a rare heterobimetallic CÀ O bond cleavage, and thus to contrasting reduced products after exposure to dihydrogen. Computational investigations provide a rationale for the divergent reactivity, while Energy Decomposition Analysis-Natural Orbital for Chemical Valence (EDA-NOCV) method substantiates the heterobimetallic bonding situation.

Introducing transition metals into frustrated Lewis pair systems has attracted considerable attention in recent years. Here we report a selection of three metal-only frustrated systems based on Au(I)/Pt(0) combinations and their reactivity towards alkynes. We have inspected the activation of the simplest alkyne, namely acetylene, as well as of other internal and terminal triply bonded hydrocarbons. The gold(I) fragments are stabilized by three bulky phosphines bearing terphenyl groups. We have observed that subtle modifications on the substituents of these ligands proved critical to control the regioselectivity of acetylene activation and the product distribution resulting from C(sp)-H cleavage of phenylacetylene. A mechanistic picture based on experimental observations and computational analysis is provided. As a result of the cooperative action of the two metals of the frustrated pairs, several uncommon heterobimetallic structures have been fully characterized.

Complex [Mo2(H)2{μ-HC(NDipp)2}2(THF)2], (1·THF), reacts with C2H4 and PhCH[double bond, length as m-dash]CH2 to afford hydrido-hydrocarbyl and bis(hydrocarbyl) derivatives of the Mo[quadruple bond, length as m-dash]Mo bond. Reversible migratory insertion and β-hydrogen elimination, as well as reductive elimination and other reactions, have been uncovered. PhC[triple bond, length as m-dash]CH behaves instead as a Brönsted-Lowry acid towards the strongly basic Mo-H bonds of 1·THF.

This contribution focuses on complex [Mo2(H)2(μ‐AdDipp2)2] (1) and tetrahydrofuran and pyridine adducts [Mo2(H)2(μ‐AdDipp2)2(L)2] (1⋅thf and 1⋅py), which contain a trans‐(H)Mo≣Mo(H) core (AdDipp2=HC(NDipp2)2; Dipp=2,6‐iPr2C6H3). Computational studies provide insights into the coordination and electronic characteristics of the central trans‐Mo2H2 unit of 1, with four‐coordinate, fourteen‐electron Mo atoms and ϵ‐agostic interactions with Dipp methyl groups. Small size C‐ and N‐donors give rise to related complexes 1⋅L but only one molecule of P‐donors, for example, PMe3, can bind to 1, causing one of the hydrides to form a three‐centered, two‐electron (3c‐2e) Mo‐H→Mo bond (2⋅PMe3). A DFT analysis of the terminal and bridging hydride coordination to the Mo≣Mo bond is also reported, along with reactivity studies of the Mo−H bonds of these complexes. Reactions investigated include oxidation of 1⋅thf by silver triflimidate, AgNTf2, to afford a monohydride [Mo2(μ‐H)(μ‐NTf2)(μ‐AdDipp2)2] (4), with an O,O’‐bridging triflimidate ligand.