Metal-to-ligand charge transfer excitations in CuI X-ray absorption spectra are introduced as spectroscopic handles for the characterization of species in homogeneous catalytic reaction mixtures. Analysis is supported by correlation of a spectral library to calculations and to complementary spectroscopic parameters.

Reaction in aqueous solution of cadmium nitrate, succinic acid (H2suc), and one of four possible isomeric dipyridylamide coligands has afforded a series of two-dimensional (2-D) and three-dimensional (3-D) coordination polymers. All were structurally characterized by single-crystal X-ray diffraction. [Cd(suc)(4-pina)] n (1, 4-pina = 4-pyridylisonicotinamide) displays a 3-D 6-connected self-penetrated 446108 mab topology, while {[Cd(suc)(3-pna)]·2.5H2O} n (2, 3-pna = 3-pyridylnicotinamide) has a simple 3-D non-interpenetrated 41263 pcu network. The supramolecular isomer 2′ has exactly the same stoichiometry and overall pcu topology as 2 but shows a difference in succinate binding mode. Compounds 1, 2, and 2′ all show similar [Cd(suc)] n layers with embedded {Cd2O2} rhomboid dimers that serve as the 6-connected nodes. {[Cd(suc)(4-pna)(H2O)]·2H2O} n (3, 4-pna = 4-pyridylnicotinamide) manifests an extremely rare 2-D 4-connected 66 layer self-penetrated topology based on cross-pillared [Cd(suc)] n helical chains. Slight adjustment of the donor disposition resulted in the formation of the 2-D (4,4) grid coordination polymer {[Cd(suc)(3-pina)(H2O)]·3.5H2O} n (4, 3-pina = 3-pyridylisonicotinamide), which has [Cd(suc)] n helical chains similar to those in 3 but avoids cross-pillaring. Luminescent and thermal properties of these four new materials are discussed.

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