Synthesis, thermal stability and structural characterisation of iron(II) phthalocyanine complex with 4-cyanopyridine

A new complex of bis-axially coordinated iron(II) phthalocyanine by 4-cyanopyridine (4-CNpy) has been obtained in crystalline form as an adduct with two 4-CNpy molecules. The [FePc(4-CNpY)21 center dot 2(4-CNpy) crystallises in the monoclinic system, space group P2(1)/c with two molecules in the unit cell. The iron(II) coordinates four isoindole nitrogen atoms of the almost planar phthalocyaninato(2-) macroring and axially two nitrogen atoms of 4-CNpy molecules. The coordination polyhedron around the Fe(II) atom approximates to a tetragonal by-pyramid. Four equatorial Fe-N bonds are shorter (1.936(2) A) than two axial Fe-N bonds (2.027(2) A). The centrosymmetric FePc(4-CNpy), molecules form alternating sheets parallel to the bc crystallographic plane and solvated 4-CNpy molecules that are anti-parallel oriented by their polar cyano groups are located between the sheets of FePc(4-CNPY)2 molecules. Ligation of the intermediate-spin iron(II) phthalocyanine by 4-CNpy molecules leads to the low spin Fe(II) complex. The importance of the d(7r) pi*(Pc) back donation is manifested in the difference between the values of C-N isoindole and C-N azamethine bond lengths of the Pc macrocycle. The thermal analysis of the crystals of [FePc(4-CN)21 center dot 2(4-CNpy) shows two steps responsible for a loss of solvated (similar to 170 degrees C and coordinated (similar to 235 degrees C 4-CNpy molecules. (c) 2007 Elsevier Ltd. All rights. reserved.