Acetonitrile-bis-(2,9-dimethyl-1,10-phen-an-throline)copper(II) bis-(tetra-fluorido-borate).

The title compound, [Cu(CH(3)CN)(C(12)H(12)N(2))(2)](BF(4))(2), crystallizes with two copper-containing cations and four tetra-fluoro-borate anions in the asymmetric unit. The structure represents a second crystal form of the salt, the first being an acetonitrile solvate [Watton (2009 ▶). Acta Cryst.

Acetonitrile-bis-(2-methyl-1,10-phenanthroline)copper(II) tetra-fluoridoborate.

In the title compound, [Cu(CH(3)CN)(C(13)H(10)N(2))(2)](BF(4))(2), the fivefold-coordinate Cu(II) atom is located on a twofold rotation axis, imposing twofold symmetry to the complete cation. The structure exhibits disorder of the anion, which was successfully refined using a two-site model with 0.810 (3):0.

Acetonitrilebis(2,9-dimethylphenanthroline)copper(II) bis(tetrafluoridoborate) acetonitrile disolvate.

In the title compound, [Cu(CH(3)CN)(C(14)H(12)N(2))(2)](BF(4))(2)·2CH(3)CN, the Cu(II) atom shows a distorted CuN(5) square-pyramidal geometry with the acetonitrile N atom in an equatorial site, which differs substanti-ally from the distorted trigonal-bipyramidal arrangement usually observed for five-coordinate complexes of Cu(II) with two phenanthroline-type ligands and one other ligand. The B atom of one of the BF(4) (-) anions is disordered over two sites in a 0.825 (2):0.

Speciation of ternary cobalt(II) phenanthroline-silica surface complexes as a function of pH and ligand steric bulk.

Co(II) solution species containing 1 equiv of phenanthroline (phen), 2-methyl-1,10-phenanthroline (MMP), or 2,9-dimethyl-1,10-phenanthroline (DMP) ligand formed inner-sphere surface complexes when grafted on silica. The speciation on the silica surface depended on both the pH of the grafting solution and the steric bulk of the ligand. [Co(DMP)](2+) formed tetrahedral surface adducts exclusively, with a 1:1 ligand-Co ratio.

Inner-sphere complexation of cobalt(II) 2,9-dimethyl-1,10-phenanthroline ([Co(neo)]2+) with commercial and sol-gel derived silica gel surfaces.

[Co(2,9-dimethyl-1,10-phenanthroline)(solvent)4]2+ ([Co(neo)]2+) undergoes a significant decrease in symmetry to form an inner-sphere surface complex when grafted directly on performed silica or introduced during the sol-gel process. The visible and X-ray absorption spectra of the surface adducts are interpreted in terms of a binding mode in which the Co(II) center has a highly distorted pseudo-C2v symmetry. The interaction of [Co(neo)]2+ with the silica surface was analyzed using an acid-base equilibrium relationship.