Tetra-, penta-, and hexacoordination in iron (II) adducts of aliphatic bidentate amines.: Crystal and molecular structure of the mononuclear complexes Fe(dienMe)Cl2 and Fe(tmeda)I2

The thf adduct of FeCl2, FeCl2(thf)(1.5), reacts with bidentate aliphatic nitrogen bases in toluene as medium to give the corresponding adducts of FeCl2. X-ray crystallography of Fe(dienMe)Cl-2 (dienMe = bis(2-dimethylaminoethyl) methylamine) has shown the compound to be mononuclear with pentacoordinated iron, thus confirming an earlier suggestion by Ciampolini and Speroni based on spectroscopic and magnetic data. Crystal data: C9H23C12FeN3; M = 300.06 g.mol(-1); monoclinic; space group p2(i)/C (No. 14); a = 8.336(3); b = 23.556(8); c = 12.108(3) Angstrom; beta = 101.22(4)degrees; V = 2947(3) Angstrom(3); Z = 8; d(calc) = 1.352 g.cm(-3); lambda(Ag-K alpha) = 0.56087 Angstrom; mu = 7.02 cm(-1) F(000) = 1264; T = 293 K. Bromo- and iodo complexes of iron (II) have been prepared by using cis-FeX2(CO)(4) (X = Br, I) as precursors. The reaction of cis-Fe(CO)(4)X-2 (X = Br, I) with N,N'-dimethylethylenediamine (dmeda) or N,N,N:N'-tetramethylethylenediamine (tmeda) in heptane as medium affords adducts of general formula Fe(NN) X-n(2) - X = Br, I; NN = dmeda, n = 2, NN = tmeda, n = 1. The iodo derivative Fe(tmeda)I-2 has been characterized by X-ray crystallography and found to be mononuclear with tetracoordinated iron (II) in a distorted tetrahedral arrangement of two iodo- and two nitrogen atoms of the bidentate amine. Crystal data: C6H16FeI2N2; M = 425.86 g mol-l; orthorhombic; space group Pbca (No. 61); a = 14.724(2); b = 15.151(4); c = 24.173(3) Angstrom; U = 5392(2) Angstrom(3); Z = 16; d(calc) = 2.098 g.cm(-3); lambda(Ag-K alpha) = 0.56087 Angstrom; mu = 29.52 cm(-1); F(000) = 3168; T = 293 K. (C) Academie des sciences/Elsevier, Paris.