Crystallographic coincidence of two bridging species in a dinuclear CoIII ethynyl­benzene complex

In the title compound, trans,trans-[μ-(m-phenyl­ene)bis­(ethyne-1,2-di­yl)]bis­[chlorido(1,4,8,11-tetra­aza­cyclo­tetra­deca­ne)cobalt(III)]–trans,trans-[μ-(5-bromo-m-phenyl­ene)bis­(ethyne-1,2-di­yl)]bis­[chlorido(1,4,8,11-tetra­aza­cyclo­tetra­deca­ne)cobalt(III)]–tetra­phenyl­borate–acetone (0.88/0.12/2/4), [Co2(C12H4)Cl2(C10H24N4)2]0.88[Co2(C10H3Br)Cl2(C10H24N4)2]0.12(C24H20B)2·4C3H6O, with the exception of the acetyl­ene and bromine groups, all atomic postitions are the same in the two compounds and are modeled at full occupancy. The CoIII ions are six-coordinate with acetyl­ide and chloride ligands bound to the axial sites and the N atoms from the cyclam rings coordinated at the equatorial positions. N—H⋯O and N—H⋯Cl hydrogen-bonding interactions help to consolidate the crystal packing

Structural and Electronic Comparison of 1st Row Transition Metal Complexes of a Tripodal Iminopyridine Ligand

We report the preparation and characterization of a series of divalent 3d transition metal complexes (Cr to Zn, <b>1</b>–<b>7)</b>, featuring the multidentate, tripodal iminopyridine Schiff-base ligand trimethyl 6,6′,6″-((1E,1′E,1″E)-((nitrilotris­(ethane-2,1-diyl))­tris­(azanylylidene))­tris-(methanylylidene))­trinicotinate (<b>L</b>^{<b>5‑OOMe</b>}). X-ray structural studies carried out on <b>1</b>–<b>5</b> and <b>7</b> reveal complex geometries ranging from local octahedral coordination to significant distortion toward trigonal prismatic geometry to heptacoordinate environments. Regardless of coordination mode, magnetic and spectroscopic studies show the ligand to provide moderately strong ligand fields: the Fe complex is low-spin, while the Co and Mn complexes are high-spin at all temperatures probed. Cyclic voltammograms exhibit multiple reversible ligand-based reductions, which are relatively consistent throughout the series; however, the electrochemical behavior of the Cr complex <b>1</b> is fundamentally different from those of the other complexes. Time-dependent (TD) density functional theory (DFT) and natural transition orbital (NTO) computational analyses are presented for the ligand, its anion, and complexes <b>1</b>–<b>7</b>: the computed spectra reproduce the major differential features of the observed visible absorption spectra, and NTOs provide viable interpretations for the observed features. The combined studies indicate that all complexes contain neutral ligands bound to M­(II) ions, except for the Cr complex <b>1</b>, which is best described as a Cr­(III) species bound to a radical anionic ligand