Carbon compounds of the transition metals. Part XXI. The crystal and molecular structure of bis[tricarbonyl-(3-chloro-2-methylnitrosobenzene)iron]

The product isolated from the reaction of 3-chloro-2-methylnitrobenzene with pentacarbonyliron is shown to be dimeric and of formula C20H12Cl2N2O8Fe2. Crystals are monoclinic with a= 18·23, b= 7·25, c= 8·71 A(±0·03%)β= 90·85°, spacegroup P21/n(C2h5, No. 14), and Z= 2. The structure was determined from 815 non-zero and visually estimated independent reflexions. The refinement, by large-block matrix least-squares, yielded a final R of 5·8%. The molecules are centrosymmetric with the two iron and two nitrogen atoms coplar. The oxygen atoms lie on either side of this plane in positions such that each is bonded to one iron atom only. Thus the nitroso-groups bridge the iron atoms unsymmetrically. The Fe ⋯ Fe distance is 3·13 A, which corresponds to a null bond.