Support of dinuclear copper triketonate complexes on silica: Monolayer loading from complex footprint and the first crystallographically characterized cis dipyridine adduct

摘要

To demonstrate that monolayer coverage of a complex can be estimated from the footprint area of the complex and surface area of the support, various loadings of two dinuclear copper complexes, bis(heptane-2,4,6-trionato)dicopper(II) [Cu-2(daa)(2)] and bis(1,5-diphenyl-1,3,5-pentanetrionato)dicopper(II) [Cu-2(dba)(2)], were supported on Cab-O-Sil by batch impregnation. The supported samples were characterized by elemental analysis, powder XRD, DRIFTS, EPR spectroscopy, and TGA. Elemental analysis and TGA data confirm that the Cu-2(daa)(2) complex loses one triketonate ligand upon adsorption onto silica from THF solution and therefore is not suitable for estimating monolayer coverage. By contrast, the Cu-2(dba)(2) complex was adsorbed on the silica surface intact from CH2Cl2. PXRD and DRIFTS confirmed the partial loading of the second Cu-2(dba)(2) layer on the Cab-O-Sil surface for samples containing >= 2.64 wt% copper. This agrees with a predicted loading based on the surface area of the support and footprint of the complex which was determined by X-ray crystallography of the dipyridine adduct. This is the first dicopper bis triketonate complex in which the pyridines are cis. (C) 2014 Elsevier B.V. All rights reserved.