A four-parameter system for rationalising the electronic properties of transition metal–radical ligand complexes

Abstract

<p>A heuristic four-parameter scheme captures and predicts the electronic properties of radical-ligand transition metal compounds, overcoming ligand specific descriptions.</p>

Ni, Pd, and Pt complexes of a tetradentate dianionic thiosemicarbazone-based O^N^N^S ligand

“…28 We found excellent agreement of predicted and experimental metrics across the entire reference set (error in bond lengths <2 pm). Taken together with the general close compliance between model and experiment of planar d 8 configured complexes, [36][37][38][39] As could be concluded from strictly diamagnetic behaviour of the complexes in the 1 H NMR spectra, all complexes exhibit close-to-ideal square planar coordination of the S^N^N^O donor set. The bond length of the coordinated C-S moiety cluster at 1.78 ± 0.01 Å, indicating dominant ene-thiolate character.…”

“…However, this seemingly deviating ordering has been observed before along the d 8 triade and is usually explained in terms of energy matching of the metal-borne binding orbitals in the case of Ni and Pt. 36,[43][44][45][46] The low-energy tailing of these bands reveals additional weaker transitions in the case of Ni and Pt which extend to λ = 650 nm. Based on the similarity to the recently studied Pt(II) complexes of the pyridinecarbaldehyde (S)-N4-(α-methylbenzyl)thiosemicarbazone (HTSCmB) ligands, 35 these broad bands are preliminarily assigned to metal-to-ligand charge transfer (MLCT) transitions.…”

“…Similar observations have been previously made for the d 8 triade in planar coordination. 36,[40][41][42]…”

DFT Investigation of the Molecular Properties of the Dimethylglyoximato Complexes [M(Hdmg)2] (M = Ni, Pd, Pt)

“…A shorter The calculated M-N bond lengths increase from 1.912 to 2.015 Å along the series Ni << Pt < Pd which reflects the size of the central atom (Tables S2-S4, Supplementary). In many experimental and theoretical studies, Pd II has been found slightly larger than Pt II [63][64][65][66][77][78][79][80][81], in keeping with the effects of the lanthanide contraction [82]. While for the Ni complex (Table S2) the two calculated M-N bonds show identical length, for Pd the M-N6(oximate) bond is slightly shorter than M-N3(oxime) (Table S3).…”

“…Recently reported DFT and TD-DFT calculations on the molecular and electronic structures of planar d 8 configured Ni II , Pd II , and Pt II complexes have shown that the reliability of calculated data with experimental data [58][59][60][61][62][63][64][65][66] is very much dependent on functionals and basis sets. Furthermore, comparative DFT and experimental studies for these three metals were recently reported [62][63][64][65][66][67] allowing to gauge for the differences of these three metals.…”