One-Dimensional Cadmium Polymers with Alternative di(EO/EE) and di(EO/EO/EO/EE) Bridged Azide Bonding Modes

Four new doubly bridged Cd(II)-azido complexes derived from sterically hindered NNN- and NN-donors were synthesized and structurally characterized. The tridentate amine ligands 2-methylquinoly1-2(ethyl-2-pyridyl)-methylamine (Meepmqa) and bis(2-methylypyridyl)methylamine (MeDPA) afforded the dinuclear complexes [Cd-2(2vIeepniqa)2(mu 1,3-N-3)2(N-3)(2)] (1) and [Cd-2(MeDPA)(2)(beta 1,1-N-3)(2)(N-3)(2)] (2) with di-EE- and di-EO-azido bridges, respectively. The N-substituted trialkyl ethylenediamine compounds N,N,N'-triethylethylenediamine (Et(3)en) and N,N,N'-trimethylethylenediamine (Me(3)en) resulted in the formation of ID polymeric chains {[Cd-2(Et(3)en)2(1/1,1-N-3)(2)(p 1,3-N-3)(2)]}, (3) and {[Cd-4(Me(3)en)(4)(pi,I-N-3)(6)(p 1,3N(3))(2)]) (4) with alternative, (di-EO/di-EE)- and di(EO/EO/EWEE)-azido bonding modes. The IR asymmetric stretching vibration, v(as)(N-3) of the azidO ligands in these complexes and in related complexes, were analyzed in an attempt to predict the coordination bonding mode of the bridged azide. The fluorescence properties of the ligand Meepmqa and its complex 1 are reported. The Cd-complex 1 has increased fluorescence intensity compared to its free ligand. This was attributed to the strong Cd N bond of the quinolyl group of Meepmqa and the nonflexibility of the corresponding five-membered chelate ring.