Synthesis, Crystal Structure, and Spectroscopic Characterization of trans-Bis[(mu-1,3-bis(4-pyridyl)propane)(mu-(3-thiopheneacetate-0))-(3-thiopheneacetate-0)]dicopper(ll), {[Cu_2CCH_2C_4H_3S)_4mu-(BPP)_2]}_n: From a Dinuclear Paddle-Wheel Copper(ll)

摘要

From the reaction between a dinuclear paddle-wheel carboxylate, namely [Cu_2mu-(O_2CCH_2C_4H_3S)_4] (1), and the flexible ligand 1,3-bis(4-pyridyl)propane (BPP) a neutral 2-D coordination polymer {[Cu_2(O_2CCH)2C_4H_3S)_4mu-(BPP)_2]}_n (2) was obtained. Compounds 1 and 2 were characterized by means of elemental analysis, thermal analysis (TG/ DSC), vibrational spectroscopy, and electron paramagnetic resonance (EPR). The crystal structure of 2 reveals that each Cu~(II) is coordinated by two nitrogen atoms from different BPP ligands and two 3-thiopheneacetate groups within a distorted square planar geometry in a trans-{N, N, 0, 0} arrangement. The BPP ligand adopts a TG conformation bridging two copper centers giving rise to a 1-D sinusoidal polymeric chain along the crystallographic c axis. Adjacent 1-D chains are extended into a 2-D coordination network through pairs of monatomic carboxylate bridges in direction of the b axis. This bridging mode affords centrosymmetric dimeric units Cu_20_2, and therefore, the copper ions are involved in a CuN_2O_2O' chromophore displaying a (4 + 1) square pyramidal coordination in the resultant 2-D polymeric network. The polycrystalline X-band EPR spectrum of 2 at room temperature is characteristic of a triplet state with nonnegligible zero-field splitting in agreement with the crystal structure. Crystal data for 2: monoclinic, space group P2_1/c, a = 9.4253(10) A, b = 10.9373(10) A, c = 23.6378(10) A, beta= 98.733(4)deg, Z = 2.