A single-component ambiphilic system capable of the cooperative activation of protic, hydridic and apolar HX bonds across a Group 13 metal/activated β-diketiminato (Nacnac) ligand framework is reported. The hydride complex derived from the activation of H2 is shown to be a competent catalyst for the highly selective reduction of CO2 to a methanol derivative. To our knowledge, this process represents the first example of a reduction process of this type catalyzed by a molecular gallium complex.

An extremely bulky boryl-amide ligand, [N(SiMe3){B(DAB)}](-) (TBoN; DAB = (DipNCH)2, Dip = C6H3Pr(i)2-2,6), has been utilised in the preparation of the first isolable, two-coordinate acyclic diaminosilylene (ADASi), viz. :Si(TBoN)2. This is shown to have a frontier orbital energy separation, and presumed level of reactivity, intermediate between those of the two classes of previously reported isolable two-coordinate, acyclic silylenes.

The first examples of an amido-distibene, L(†)Sb[double bond, length as m-dash]SbL(†) (L(†) = -N(Ar(†))(SiPr(i)3), Ar(†) = C6H2{C(H)Ph2}2Pr(i)-2,6,4), and a boryl dibismuthene, {(DAB)B}Bi[double bond, length as m-dash]Bi{B(DAB)} (DAB = {(C6H3Pr(i)2-2,6)NCH}2, have been prepared by reaction of a lithium boryl complex, (THF)2LiB(DAB), with extremely bulky amido-group 15 dihalide precursor compounds. In these reactions, the lithium boryl acts as a boryl transfer reagent and/or a strong reducing agent.

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Thermally robust expanded ring carbene adducts of AlH3 have been synthesized with a view to probing their ligating abilities via Al-H σ-bond coordination. While κ(2) binding to the 14-electron [Mo(CO)4] fragment is readily demonstrated, interaction with [Mo(CO)3] results in μ:κ(1),κ(1) and μ:κ(2),κ(2) bridging linkages rather than terminal κ(3) binding.

The modes of interaction of donor-stabilized Group 13 hydrides (E=Al, Ga) were investigated towards 14- and 16-electron transition-metal fragments. More electron-rich N-heterocyclic carbene-stabilized alanes/gallanes of the type NHC⋅EH3 (E=Al or Ga) exclusively generate κ(2) complexes of the type [M(CO)4 (κ(2)-H3 E⋅NHC)] with [M(CO)4 (COD)] (M=Cr, Mo), including the first κ(2) σ-gallane complexes. β-Diketiminato ('nacnac')-stabilized systems, {HC(MeCNDipp)2 }EH2 , show more diverse reactivity towards Group 6 carbonyl reagents. For {HC(MeCNDipp)2 }AlH2, both κ(1) and κ(2) complexes were isolated, while [Cr(CO)4 (κ(2)-H2 Ga{(NDippCMe)2 CH})] is the only simple κ(2) adduct of the nacnac-stabilized gallane which can be trapped, albeit as a co-crystallite with the (dehydrogenated) gallylene system [Cr(CO)5 (Ga{(NDippCMe)2 CH})]. Reaction of [Co2 (CO)8] with {HC(MeCDippN)2 }AlH2 generates [(OC)3 Co(μ-H)2 Al{(NdippCme)2 CH}][Co(CO)4] (12), which while retaining direct AlH interactions, features a hitherto unprecedented degree of bond activation in a σ-alane complex.

Reduction of indium boryl precursors to give two- and three-dimensional M-M bonded networks is influenced by the choice of supporting ligand. While the unprecedented nanoscale cluster [In (boryl) ] (with an In @In @In (boryl) concentric structure), can be isolated from the potassium reduction of a bis(boryl)indium(III) chloride precursor, analogous reduction of the corresponding (benzamidinate)In Br(boryl) system gives a near-planar (and weakly aromatic) tetranuclear [In (boryl) ] system.

Bond activation at a transition metal centre is a key fundamental step in numerous chemical transformations. The oxidative addition of element-hydrogen bonds, for example, represents a critical step in a range of widely applied catalytic processes. Despite this, experimental studies defining steps along the bond activation pathway are very rare. In this work, we report on fundamental studies defining a new oxidative activation pathway: combined experimental and computational approaches yield structural snapshots of the simultaneous activation of both bonds of a β-diketiminate-stabilized GaH unit at a single metal centre. Systematic variation of the supporting phosphine ligands and single crystal X-ray/neutron diffraction are exploited in tandem to allow structural visualization of the activation process, from a η-H,H σ-complex showing little Ga-H bond activation, through species of intermediate geometry featuring stretched Ga-H and compressed M-H/M-Ga bonds, to a fully activated metal dihydride featuring a neutral (carbene-type) N-heterocyclic Ga ligand.