A Crystalline NiX Complex.

High-valent nickel species are implicated as intermediates in industrially relevant chemical transformations and in the catalytic cycles of metalloenzymes. Although a small number of tetravalent NiX complexes have been crystallographically characterized, higher nickel valence states have not been identified. Here we report a stable, crystalline NiX complex, Ni(BeCp) (; cyclopentadienyl anion (Cp)), formed by the insertion of zerovalent nickel into three Be-Be bonds.

On the nature and limits of alkaline earth-triel bonding.

The synthesis of a series of isostructural organometallic complexes featuring Ae-Tr bonds (Ae = Be, Mg; Tr = Al, Ga, In) has been investigated, and their electronic structures probed by quantum chemical calculations. This systematic study allows for comparison, not only of the metal-metal bonding chemistries of the two lightest alkaline earth (Ae) elements, beryllium and magnesium, but also of the three triel (Tr) elements, aluminium, gallium, and indium. Computational analyses (NBO, QTAIM, EDA-NOCV) reveal that Be-Tr bonding is more covalent than Mg-Tr bonding.

A nucleophilic beryllyl complex via metathesis at [Be-Be].

Owing to its high toxicity, the chemistry of element number four, beryllium, is poorly understood. However, as the lightest elements provide the basis for fundamental models of chemical bonding, there is a need for greater insight into the properties of beryllium. In this context, the chemistry of the homo-elemental Be-Be bond is of fundamental interest.

Alkaline earth metals: homometallic bonding.

The study of alkaline earth metal complexes is undergoing a renaissance. Stable molecular species featuring Mg-Mg bonds were reported in 2007 and their reactivity has since been intensively investigated. Motivated by this work, efforts have also been devoted to the synthesis of complexes featuring Be-Be and Ca-Ca bonds.

Diberyllocene, a stable compound of Be(I) with a Be-Be bond.

The complex diberyllocene, CpBeBeCp (Cp, cyclopentadienyl anion), has been the subject of numerous chemical investigations over the past five decades yet has eluded experimental characterization. We report the preparation and isolation of the compound by the reduction of beryllocene (BeCp) with a dimeric magnesium(I) complex and determination of its structure in the solid state by means of x-ray crystallography. Diberyllocene acts as a reductant in reactions that form beryllium-aluminum and beryllium-zinc bonds.

Inducing Nucleophilic Reactivity at Beryllium with an Aluminyl Ligand.

The reactions of anionic aluminium or gallium nucleophiles {K[E(NON)]} (E = Al, ; Ga, ; NON = 4,5-bis(2,6-diisopropylanilido)-2,7-di-butyl-9,9-dimethylxanthene) with beryllocene (BeCp) led to the displacement of one cyclopentadienyl ligand at beryllium and the formation of compounds containing Be-Al or Be-Ga bonds (NON)EBeCp (E = Al, ; Ga, ). The Be-Al bond in the beryllium-aluminyl complex [2.310(4) Å] is much shorter than that found in the small number of previous examples [2.

Carbene Complexes of Neptunium.

Since the advent of organotransuranium chemistry six decades ago, structurally verified complexes remain restricted to π-bonded carbocycle and σ-bonded hydrocarbyl derivatives. Thus, transuranium-carbon multiple or dative bonds are yet to be reported. Here, utilizing diphosphoniomethanide precursors we report the synthesis and characterization of transuranium-carbene derivatives, namely, diphosphonio-alkylidene- and -heterocyclic carbene-neptunium(III) complexes that exhibit polarized-covalent σπ multiple and dative σ single transuranium-carbon bond interactions, respectively.

A crystalline tri-thorium cluster with σ-aromatic metal-metal bonding.

Metal-metal bonding is a widely studied area of chemistry, and has become a mature field spanning numerous d transition metal and main group complexes. By contrast, actinide-actinide bonding, which is predicted to be weak, is currently restricted to spectroscopically detected gas-phase U and Th (refs. ), UH and UH in frozen matrices at 6-7 K (refs.

Heteroleptic actinocenes: a thorium(iv)-cyclobutadienyl-cyclooctatetraenyl-di-potassium-cyclooctatetraenyl complex.

Despite the vast array of η -carbocyclic C complexes reported for actinides, cyclobutadienyl (C) remain exceedingly rare, being restricted to six uranium examples. Here, overcoming the inherent challenges of installing highly reducing C-ligands onto actinides when using polar starting materials such as halides, we report that reaction of [Th(η-CH)] with [K{C(SiMe)}] gives [{Th(η-C[SiMe])(μ-η-CH)(μ-η-CH)(K[CHMe])}{K(CHMe)}{K}] (), a new type of heteroleptic actinocene. Quantum chemical calculations suggest that the thorium ion engages in π- and δ-bonding to the η-cyclobutadienyl and η-cyclooctatetraenyl ligands, respectively.

Fragmentation, catenation, and direct functionalisation of white phosphorus by a uranium(IV)-silyl-phosphino-carbene complex.

Room temperature reaction of the uranium(iv)-carbene [U{C(SiMe3)(PPh2)}(BIPMTMS)(μ-Cl)Li(TMEDA)(μ-TMEDA)0.5]2 (1, BIPMTMS = C(PPh2NSiMe3)2) with white phosphorus (P4) produces the organo-P5 compound [P5{C(SiMe3)(PPh2)}2][Li(TMEDA)2] (2) and the uranium(iv)-methanediide [U{BIPMTMS}{Cl}{μ-Cl}2{Li(TMEDA)}] (3). This is an unprecedented example of cooperative metal-carbene P4 activation/insertion into a metal-carbon double bond and also an actinide complex reacting with P4 to directly form an organophosphorus species.

Insights into the Composition and Structural Chemistry of Gallium(I) Triflate.

"GaOTf" is a simple, convenient source of low-valent gallium for synthetic chemistry and catalysis. However, little is currently known about its composition or reactivity. In this work, Ga NMR spectroscopy shows the presence of [Ga(arene) ] salts on oxidation of Ga metal with AgOTf in arene solvents.

f-Element Half-Sandwich Complexes: A Tetrasilylcyclobutadienyl-Uranium(IV)-Tris(tetrahydroborate) Anion Pianostool Complex.

Despite there being numerous examples of f-element compounds supported by cyclopentadienyl, arene, cycloheptatrienyl, and cyclooctatetraenyl ligands (C ), cyclobutadienyl (C ) complexes remain exceedingly rare. Here, we report that reaction of [Li {C (SiMe ) }(THF) ] (1) with [U(BH ) (THF) ] (2) gives the pianostool complex [U{C (SiMe ) }(BH ) ][Li(THF) ] (3), where use of a borohydride and preformed C -unit circumvents difficulties in product isolation and closing a C -ring at uranium. Complex 3 is an unprecedented example of an f-element half-sandwich cyclobutadienyl complex, and it is only the second example of an actinide-cyclobutadienyl complex, the other being an inverse-sandwich.

Back-bonding between an electron-poor, high-oxidation-state metal and poor π-acceptor ligand in a uranium(V)-dinitrogen complex.

A fundamental bonding model in coordination and organometallic chemistry is the synergic, donor-acceptor interaction between a metal and a neutral π-acceptor ligand, in which the ligand σ donates to the metal, which π back-bonds to the ligand. This interaction typically involves a metal with an electron-rich, mid-, low- or even negative oxidation state and a ligand with a π* orbital. Here, we report that treatment of a uranium-carbene complex with an organoazide produces a uranium(V)-bis(imido)-dinitrogen complex, stabilized by a lithium counterion.

Silyl-Phosphino-Carbene Complexes of Uranium(IV).

Unprecedented silyl-phosphino-carbene complexes of uranium(IV) are presented, where before all covalent actinide-carbon double bonds were stabilised by phosphorus(V) substituents or restricted to matrix isolation experiments. Conversion of [U(BIPM )(Cl)(μ-Cl) Li(THF) ] (1, BIPM =C(PPh NSiMe ) ) into [U(BIPM )(Cl){CH(Ph)(SiMe )}] (2), and addition of [Li{CH(SiMe )(PPh )}(THF)]/Me NCH CH NMe (TMEDA) gave [U{C(SiMe )(PPh )}(BIPM )(μ-Cl)Li(TMEDA)(μ-TMEDA) ] (3) by α-hydrogen abstraction. Addition of 2,2,2-cryptand or two equivalents of 4-N,N-dimethylaminopyridine (DMAP) to 3 gave [U{C(SiMe )(PPh )}(BIPM )(Cl)][Li(2,2,2-cryptand)] (4) or [U{C(SiMe )(PPh )}(BIPM )(DMAP) ] (5).