Hydrocarbon bridged metal complexes, XLIV. Donor–acceptor substituted Schiff bases of polyenes with transition metals2

Photoisomerisation of Exo-Imine Complexes and the Role of MECP in the Reverse Thermal Equilibrium: An Experimental and DFT Computational Investigation

Complexes [MCl2 Cp*]2 (M=Ir, Rh), [RuCl2 (p-cymene)]2 and [Ir(C^N)2 Cl]2 (HC^N=a, phenylpyridine ; b, phenylpyrazole,) react with imine ligands derived from ο-aminophenol to yield complexes with an exocyclic C=N bond which has a cis or trans configuration. The trans isomer is favoured except for sterically crowded complexes Cp*M (M=Ir, Rh) when the imine has a mesityl substituent, for which the cis isomer is favoured. The complexes undergo photoisomerisation in visible light but revert back to the original isomer over time or when heated. The rate of the thermal reverse isomerisation depends on the imine substituent and the metal fragment. DFT calculations correctly reproduce the favoured isomer and suggest that the reverse isomerisation occurs by a rehybridisation at the N atom as found in organic imines. In addition, a triplet state, thermally accessible by a Minimum Energy Crossing Point (MECP) provides a low energy pathway for reverse isomerisation in the case of the half-sandwich complexes.

Heteroligand Metal Complexes with Extended Redox Properties Based on Redox-Active Chelating Ligands of o-Quinone Type and Ferrocene

A combination of different types of redox-active systems in one molecule makes it possible to create coordination compounds with extended redox abilities, combining molecular and electronic structures determined by the features of intra- and intermolecular interactions between such redox-active centres. This review summarizes and analyses information from the literature, published mainly from 2000 to the present, on the methods of preparation, the molecular and electronic structure of mixed-ligand coordination compounds based on redox-active ligands of the o-benzoquinone type and ferrocenes, ferrocene-containing ligands, the features of their redox properties, and some chemical behaviour.

Crystal structure of (E)-2-hydroxy-4′-methoxyazastilbene

The title compound has an E conformation with respect to the azomethine C=N bond and the aromatic rings are inclined to one another by 3.29 (4)°. In the crystal, mol­ecules are linked via C—H⋯O hydrogen bonds, forming zigzag chains along [10-1].

The title aza­stilbene derivative, C₁₄H₁₃NO₂ {systematic name: (E)-2-[(4-meth­oxy­benzyl­idene)amino]­phenol}, is a product of the condensation reaction between 4-meth­oxy­benzaldehyde and 2-amino­phenol. The mol­ecule adopts an E conformation with respect to the azomethine C=N bond and is almost planar, the dihedral angle between the two substituted benzene rings being 3.29 (4)°. The meth­oxy group is coplanar with the benzene ring to which it is attached, the C_meth­yl—O—C—C torsion angle being −1.14 (12)°. There is an intra­molecular O—H⋯N hydrogen bond generating an S(5) ring motif. In the crystal, mol­ecules are linked via C—H⋯O hydrogen bonds, forming zigzag chains along [10-1]. The chains are linked via C—H⋯π inter­actions, forming a three-dimensional structure.