Structural and Electronic Studies of Substituted m-Terphenyl Group 12 Complexes

The effects of para-substitution on the structural and electronic properties of four series of two-coordinate m-terphenyl Group 12 complexes (R-Ar^#)₂M (M = Zn, Cd, Hg; R = t-Bu 1–3, SiMe₃4–6, Cl 7–9, CF₃10–12, where R-Ar^# = 2,6-{2,6-Xyl}₂-4-R-C₆H₂ and 2,6-Xyl = 2,6-Me₂C₆H₃) have been investigated. X-ray crystallography shows little structural variation across the series, with no significant change in the C–M–C bond distances and angles. However, considerable electronic differences are revealed by heteronuclear nuclear magnetic resonance (NMR) spectroscopy; a linear correlation is observed between the ¹¹³Cd, ¹⁹⁹Hg, and ¹H (2,6-Xyl methyl protons) NMR chemical shifts of the para-substituted complexes and the Hammett constants for the R-substituents. Specifically, an upfield shift in the NMR signal is observed with increasingly electron-withdrawing R-substituents. Density functional theory (DFT) calculations are employed to attempt to rationalize these trends.

Low-coordinate first-row transition metal complexes in catalysis and small molecule activation

In this Perspective, we will highlight selected examples of transition metal complexes with low coordination numbers whose high reactivity has been exploited in catalysis and the activation of small molecules featuring strong bonds (N₂, CO₂, and CO).

Cyclotrimerisation of isocyanates catalysed by low-coordinate Mn(ii) and Fe(ii) m-terphenyl complexes

Isocyanurates can be synthesised through the cyclotrimerisation of primary isocyanates catalysed by low-coordinate manganese(ii) and iron(ii) m-terphenyl complexes under mild conditions.

Ligand influences on homoleptic Group 12 m-terphenyl complexes

The analysis of three series of two-coordinate Group 12 bis-terphenyl complexes highlights how subtle changes to ligand properties, particularly sterics, and, to a smaller extent, electronics have a large effect on the solid state structures adopted.