Synthesis, characterization, and single crystal X-ray structures of [CoIII((BA)2en)(thiobenzamide)2]PF6 and [CoIII(acacen)(thiobenzamide)2]ClO4 and their solvatochromic properties

Abstract

New cobalt(III) complexes of two tetradentate Schiff base ligands, acacen = bis(acetylacetone)ethylenediimine dianion and (BA) 2 en = bis(benzoylacetone)-ethylenediimine dianion, with two axial thiobenzamide (tb) ligands have been synthesized by solid state methods and characterized by elemental analyses, IR, UV-Vis, and 1 H-NMR spectroscopy. Both complexes show solvatochromism in a variety of solvents. The crystal and molecular structures of (1) and (2) were determined by X-ray crystallography. The structure (1) contains two independent [Co III ((BA) 2 en)(tb) 2 ] ? complexes, two independent PF 6 anions, and one well ordered ethyl acetate solvent molecule per asymmetric unit. In contrast, the structure (2) contains two independent [Co III (acacen)(tb) 2 ] ? complexes of C 2 symmetry, a disordered ClO 4 group and disordered toluene molecules. The octahedral coordination of Co(III) is distorted and the Schiff base ligands (ONNO donors) coordinate the cobalt ion in four equatorial positions, and the two axial positions are occupied by S-bonded thiobenzamide molecules. Intramolecular N-HÁÁÁO hydrogen bonds donated by the thiobenzamide molecules add to the stability of the complexes in the solid state. The IR, UV-Vis, and 1 H-NMR spectra of the two complexes and their solvatochromic properties are also discussed. The compounds exhibit LLCT mediated by the metal center.

Switching metal complexesviaintramolecular electron transfer: connections with solvatochromism

“…An absorption in the visible region (between around 450 to 600 nm, depending on the complex) shifts to shorter wavelengths as the solvent donor number is increased, due to a reversible equilibrium involving substitution of the axial ligands by coordinated solvent. [95][96][97] For [Co III (saox)(bipy) 2 ] + (22; H 2 saox = salicylaldoxime), specific solvent-solute interactions cause changes in Δ oct that in turn, affect the energies of the 1 A 1g → 3 T 1g and 1 A 1g → 3 T 2g transitions. 98 In this case, the band wavelengths do not correlate with any of the solvatochromic parameters discussed earlier.…”

Synthesis of Rhodium–Primary Thioamide Complexes and Their Desulfurization Leading to Rhodium Sulfido Cubane-Type Clusters and Nitriles

“…Thioamides, sulfur analogues of carboxamides, act as versatile and interesting ligands in coordination chemistry, because they and their deprotonated species, thioamidate anions, can take various coordination geometries such as S -bonded, − N , S -chelating, N , S -bridging, , and S , S -bridging (Chart ). , Among those, thioamide-based pincer-type ligands have been received considerable attention in recent years. , Some thioamide complexes of palladium and rhodium show catalytic performance in reactions such as cross-coupling ,, and asymmetric hydrogenation of carbonyl compounds. , Since the sulfur atoms in thioamides are less prone to be oxidized in comparison with commonly used organophosphorus ligand, thioamide-based palladium complexes can serve as a good catalyst even under aerobic conditions for Suzuki–Miyaura cross-coupling and Mizoroki–Heck reaction. , …”

“…Although molecular thioamide complexes have been known for more than 30 years − and have attracted considerable attention as described above, fundamental chemistry of primary thioamide complexes with late-transition metals remains unexplored; only one organometallic ruthenium complex and very few coordination compounds of nickel , and cobalt , were crystallographically characterized. Now we have synthesized a series of simple rhodium complexes with a primary arenecarbothioamide ligand [Cp*RhCl 2 {SC(Ar)NH 2 -κ 1 S }].…”