Synthesis, Structural Features, and Catalytic Activity of an Iron(II) 3D Coordination Polymer Driven by an Ether-Bridged Pyridine-Dicarboxylate

Abstract

New iron(II) three-dimensional coordination polymer (3D CP), [Fe(µ3-Hcpna)2]n (1), was assembled under hydrothermal conditions from 5-(4’-carboxyphenoxy)nicotinic acid (H2cpna) as a trifunctional organic N,O-building block. This stable microcrystalline CP was characterized by standard methods for coordination compounds in the solid state (infrared spectroscopy, elemental analysis, thermogravimetric analysis, powder and single-crystal X-ray diffraction). Structure and topology of 1 were examined and permitted an identification of a 3,6-connected framework of the rtl topological type. In addition, compound 1 acts as effective catalyst precursor for oxidative functionalization of alkanes (propane and cyclic C5−C8 alkanes) under homogeneous catalysis conditions, namely for the oxidation of saturated hydrocarbons with H2O2/H+ system to produce ketones and alcohols, and for alkane carboxylation with CO/H2O/S2O82− system to obtain carboxylic acids. The influence of an acid promoter and substrate scope (propane and cyclic C5−C8 alkanes) were investigated.

Coordination Polymer Based on a Triangular Carboxylate Core {Fe(μ3-O)(μ-O2CR)6} and an Aliphatic Diamine

“…Coordination polymers are formed by binding metal ions or metal-containing cores with bridging ligands, whose variation in structure-forming parameters allows for control over the polymer's structure [1][2][3][4][5][6][7][8][9][10], as well as luminescent [11][12][13][14], sorption [4,[15][16][17][18], magnetic [19][20][21][22], and other properties. Iron(II) coordination polymers exhibit selective catalytic activity in the hydroboration of aldehydes and ketones [23], the oxidative functionalization of alkanes [24], and in dimerization reactions of aromatic halogen derivatives [25]. Mixed-valent derivatives with a metal core {Fe II Fe III Fe III O} can be used in the creation of molecular switches [3,26,27].…”