Carbon monoxide is a key C₁ feedstock for the industrial production of hydrocarbons, where it is used to make millions of tonnes of chemicals, fuels, and solvents per annum. Many transition metal complexes can coordinate CO, but the formation of new C−C bonds in well-defined compounds from the scission and subsequent coupling of two or more CO moieties at a transition metal centre remains a challenge. Herein, we report the use of low-coordinate iron(II) complexes for the selective scission and homologation of CO affording unusual squaraines and iron carboxylates at ambient temperature and pressure. A modification of the ligand framework allows for the isolation and structural characterisation of a proposed metallacyclic Fe(II) carbene intermediate. These results indicate that, with the appropriate choice of supporting ligands, it is possible to cleave and homologate carbon monoxide under mild conditions using an abundant and environmentally benign low-coordinate, first row transition metal.

Two- and three-coordinate m-terphenyl complexes of manganese and iron are efficient catalysts for the selective cyclotrimerisation of primary aliphatic isocyanates affording isocyanurates in short reaction times and under mild conditions.

Two- and three-coordinate manganese m-terphenyl complexes are precatalysts for the dehydrogenation of dimethylamine–borane (Me₂NH·BH₃) affording one equivalent of molecular hydrogen and half an equivalent of [Me₂N–BH₂]₂. Experimental studies into the nature of the catalyst indicate that small changes in the coordination environment give rise to significant differences in the reaction mechanism, occurring through a homogeneous mechanism for two-coordinate precatalysts, whilst for the three-coordinate species a heterogeneous mechanism takes place where nanoparticles are responsible for the catalysis.

Three m-terphenyl ligands 2,6-Ar₂C₆H₃ ⁻ [Ar = 2,6-Me₂C₆H₃ (2,6-Xyl); 3,5-Me₂C₆H₃ (3,5-Xyl); 2,3,4,5,6-Me₅C₆ (Pmp)] have been used to stabilise three series of two-coordinate Group 12 diaryl complexes; (2,6-Ar₂C₆H₃)₂M [M = Zn, Cd, Hg, Ar = 2,6-Xyl 1–3, 3,5-Xyl 4–6, Pmp 7–9], where differing steric demands on the metal centres are imparted. These are the first homoleptic d-block complexes featuring any of these ligands. Complexes 1–9 have been characterised in solution and the solid state; the analysis of structural changes produced by differences in ligand properties is reported. In particular, complexes 4–6 show smaller C–M–C bond angles and contain secondary ligand interactions that are not seen in the analogous complexes 1–3 and 7–9.

Synthesis of a chiral molecular metal which remains metallic down to at least 4.2 K and exhibits room-temperature switching capabilities.

We report the first example of a chiral BDH-TTP radical-cation salt. Chirality is induced in the structure via the use of a chiral spiroboronate anion where three stereocentres are present, one on each chiral ligand and one on the boron centre. Despite starting from a labile racemic mixture of B_S and B_R enantiomers, only one enantiomer is present in the crystal lattice. The anions pack in a novel double anion layer which is the thickest anion layer found in a BDH-TTP salt. This material is chiral and shows metallic behaviour down to at least 4.2 K.