No abstract

The bis‐chelate tin complex 1, based on the 4,6‐di‐tert‐butyl‐N‐(tert‐butyl)‐ortho‐aminophenol ligand and representing the first example of a redox‐isomeric compound in main‐group chemistry, is synthesized and characterized by X‐ray diffraction analysis. Complex 1 exists in two electromeric forms in nonpolar solvents: a diamagnetic pseudotetrahedral (AP)2SnIV (1a) and a paramagnetic tetragonal‐pyramidal structure of low‐valence tin (imSQ)2SnII (1b) (where AP and imSQ are the dianionic and radical‐anionic forms of the ligand, respectively). The reversible redox‐isomeric rearrangement between 1a and 1b is investigated in solution by means of magnetochemistry, EPR spectroscopy, UV/Vis spectroscopy, and 119Sn Mössbauer spectroscopy. This interconversion can be quenched by an addition of a strong donor ligand, such as pyridine (Py), resulting in an octahedral complex (AP)2SnIV(Py)2 (2) that does not undergo redox isomerism.

The reactivity of tin(II) catecholate complex CatSn (1) (where Cat = 3,6‐di‐tert‐butylcatecholate dianion) and two o‐amidophenolate complexes DippAPSn (2) and PhAPSn (3) [where DippAP = 4,6‐di‐tert‐butyl‐N‐(2,6‐diisopropylphenyl)amidophenolate; PhAP = 4,6‐di‐tert‐butyl‐N‐(phenyl)amidophenolate dianions] towards different reagents is reported. Products of the insertion of 1 and 2 into the S–S bond of tetramethylthiuram disulfide were obtained and characterised by X‐ray diffraction analyses. The low temperature oxidation of complexes 1 and 2 with 2‐ethoxy‐3,6‐di‐tert‐butylphenoxy radical enabled us to detect formation of paramagnetic tin(II) derivatives containing the radical‐anion form of the redox‐active ligand. The reaction of tin derivative 3 with Ni(CO)4 leads to substitution of one of the CO groups in the latter with the formation of a new bimetallic product.

Abstract:The potential valence tautomeric (VT) properties of bischelate complexes of group 14 elements with 2,6-di-tertbutyl-4-[(3,5-di-tert-butyl-2-hydroxyphenyl)imino]cyclohexa-2,5-dienone (I) and 4,6-di-tert-butyl-N-(R)-o-aminophenol (II, R = Ph and tBu) were studied computationally. According to DFT B3LYP/6-311++G(d,p)/SDD calculations, the silicon complexes will be present as Si IV isomers with pseudotetrahedral coordination sites. Geometry optimizations of both lead bischelates I and II result in tetragonal-pyramidal Pb II structures. In the germanium complex I, the energy difference (5.2 kcal mol -1

Bimetallic coordination compounds prone to spin‐state‐switching rearrangements via spin‐crossover or valence tautomerism mechanisms are of ongoing interest due to their unique magnetic characteristics. Dinuclear transition metal (Cr, Mn, Fe, Co, Ni, Cu) complexes with redox‐active bridging ligands (tetraoxolenes and their imine derivatives, di‐o‐quinones bearing linker groups) and tetradentate nitrogen‐containing bases (tetraazacyclotetradecane, tris(2‐pyridylmethyl)amine and N,N′‐dialkyl‐2,11‐diaza[3.3]‐(2,6)pyridinophane derivatives) are described from the viewpoint of their electronic structure and magnetic properties. The present review summarizes data on comprehensive investigations of bi‐ and polystable species of such structural architectures, which might be valuable for the chemists and materials scientists involved in the creation of new promising magnetic materials − building blocks for electronic devices of future generations.