Spin-state switching: chemical modulation and the impact of intermolecular interactions in manganese(III) complexes.

A series of mononuclear manganese(III) complexes [Mn(X-sal-323)](ReO) (X = 5 Cl, 1; X = 5 Br, 2; X = 3,5 Cl, 3; X = 3,5 Br, 4; and X = 5 NO, 5), containing hexadentate ligands prepared using the condensation of ,'-bis(3-aminopropyl)ethylenediamine and 5- or 3,5-substituted salicylaldehyde, has been synthesized. Variable temperature single-crystal X-ray diffraction, magnetic, spectroscopic, electrochemical, and spectroelectrochemical analyses, and theoretical calculations have been used to explore the role of various ligand substituents in the spin-state switching behavior of the prepared manganese(III) complexes. All five complexes consist of an analogous distorted octahedral monocationic MnNO surrounding offered by the flexible hexadentate ligand and ReO as the counter anion.

Impact of counter anions on spin-state switching of manganese(III) complexes containing an azobenzene ligand.

Four mononuclear manganese(III) complexes coordinated with photo-active hexadentate azobenzene ligands, [Mn(5azo-sal-323)](X) (X = Cl, 1; X = BF, 2; X = ClO, 3; X = PF, 4), were prepared. The impact of various counter anions on the stabilization and switching of the spin state of the manganese(III) center was explored through detailed magneto-structural investigation using variable temperature single-crystal X-ray diffraction, magnetic, spectroscopic, and spectroelectrochemical studies, along with theoretical calculations. All four complexes consisted of an isostructural monocationic distorted octahedral MnNO coordination environment offered by the hexadentate ligand and Cl, BF, ClO, and PF as counter anions respectively.

Effect of ligand substituents and tuning the spin-state switching in manganese(iii) complexes.

Three mononuclear manganese(iii) complexes based on flexible hexadentate ligands obtained from the condensation of N,N'-bis(3-aminopropyl)ethylenediamine and salicylaldehyde or salicylaldehyde with substitutions at the 5 or 3,5 positions, namely [Mn(X-sal-323)](BPh) (X = 5 H, 1; X = 5 Br, 2, and X = 3,5 Br, 3) have been synthesized. The impact of ligand substituents has been studied by variable temperature single-crystal X-ray diffraction analyses, and magnetic, spectroscopic and electrochemical investigations. The complexes have an analogous monocationic MnNO surrounding offered by the flexible hexadentate ligand in a distorted octahedral geometry.

Stepwise spin-state switching in a manganese(III) complex.

A mononuclear manganese(iii) complex containing a flexible hexadentate chelating ligand has been prepared and characterized by performing, at various temperatures, single-crystal X-ray diffraction analyses and magnetic, spectroscopic, and electrochemical studies. The complex was shown to consist of an MnN4O2 octahedral coordination environment, and to exhibit reversible two-step thermally induced spin-state switching, a gradual one at 168 K and an abrupt one at 103 K. Structural analyses revealed the existence of three spin-states, namely high-spin, low-spin, and intermediate states, during the spin-state switching process.

Homocubane Chemistry: Synthesis and Structures of Mono- and Dicobaltaheteroborane Analogues of Tris- and Tetrahomocubanes.

Room-temperature reactions between [Cp*CoCl] (Cp* = η-CMe) and large excess of [BHE]Li (E = S or Se) led to the formation of homocubane derivatives, . These species are bimetallic tetrahomocubane, [(Cp*Co)(μ-S)(μ-S)BH], ; bimetallic trishomocubane isomers, [(Cp*Co)(μ-S)(μ-S)BH], and ; monometallic trishomocubanes, [M(μ-E)(μ-E)BH] [: M = Cp*Co, E = S; : M = Cp*Co, E = Se and : M = {(Cp*Co)(μ-H)(μ-Se)}Co, E = Se], and bimetallic homocubane, [(Cp*Co)(μ-Se)(μ-Se)BH], . As per our knowledge, is the first isolated and structurally characterized parent prototype of the 1,2,2',4 isomer of tetrahomocubane, while , , and are the analogues of parent -trishomocubane.