Self-assembly of a Mixed-valence Cu(Ⅰ)/Cu(Ⅱ) Coordination Polymer Derived from a Conformationally Flexible Tripodal Phosphoric Trimide Ligand

Reaction of a tripodal ligand, N,N?,N??-tris（3-pyridinyl） phosphoric trimide（TPPA） and CuBr;·2H;O result in the assembly of a new polymeric copper coordination polymer, which was characterized by single-crystal diffraction, infrared spectroscopy and elemental analysis. The polymer crystallizes in the triclinic system, space group P1 with a = 9.0964（5）, b = 10.2592, c = 10.5822（8） ?, V = 933.01（9） ?;, Z = 2, C;H;Br;Cu;N;O;P;, M;= 985.02, D;= 1.753 g/cm;, F（000） = 4072 and μ（MoKα） = 0.746 mm;. The final R and w R are 0.0588 and 0.1329 for 4260 observed reflections with I > 2σ（I）. Cu（Ⅰ） is tetrahedrally coordinated and Cu（Ⅱ） center adopts square planar coordination geometry. Because of the flexibility of the TPPA ligands, the pyridyl rings rotate though a certain angle and three pyridyl rings on the same TPPA rotate by about 45° with respect to the central P=O groups. TPPA ligand acts as a tridentate ligand and is coordinated with three metal centers with its pyridyl donors to form a 2D-sheet like structure, and it is further connected by N–H···O and N–H···Br, resulting in a 3D network packing. Oxidation states of the metal center have been determined by bond valence sum calculation.