New polynuclear compounds of iron(II) chloride with oxygen donor ligands Part II. Polymeric [FeCl 2(OPMe 3)] ∞ and mononuclear FeCl 2(OPMe 3) 2. Syntheses, properties and single crystal structure determinations

Abstract

A new polymeric Fe(II) chloride complex, [FeCl 2(OPMe 3)] ∞ ( 1), has been synthesized from the reaction of stoichiometric quantities of FeCl 3, Fe and OPMe 3 (2:1:3) in THF. Use of a 2:1:6 ratio in the above reaction gives instead the mononuclear complex FeCl 2(OPMe 3) 2 ( 2). The structure of the polymer consists of infinite chains of FeCl 2(OPMe 3) units, where each Fe atom is linked by four bridging chlorine atoms to two other Fe atoms. The arrangement of the four chlorine atoms and one OPMe 3 molecule around the iron atom results in a trigonal bipyramidal coordination geometry. Complex 2 has tetrahedral geometry. The magnitudes of the magnetic moments for 1 and 2 at room temperature are 4.90 and 5.51 BM, respectively, indicative of high spin Fe 2+. In 1, two different Fe…Fe distances 3.560(0) and 3.688(0) Å alternate along the chain, the FeCl bond distances are in the range 2.35–2.60 Å, the FeO distance is 1.954(2) Å and the PO distance is 1.513(2) Å. In 2, the FeCl distances average to 2.291(4) Å, the average FeO and PO distances are 1.994(2) and 1.504(1) Å, respectively. Crystallographic data: 1, monoclinic, space group P2 1/ n, a=6.810(2), b=12.943(5), c=9.645(2) Å, β=100.224(2)°, V=836.6(11) Å 3, Z=4, R=O.041 ( R w=0.058) for 101 parameters and 1665 unique data having F o 2>3σ( F o 2). 2, orthorhombic, space group P2 12 12 1, a=11.270(3), b=12.011(2), c=10.811(2) Å, V=1463.5(5) Å 3, Z=4, R=0.052 ( R w=0.064) for 142 parameters and 1356 unique data having F o 2>3σ( F o 2).