Novel polynuclear iron carbonyl complexes containing phosphorus and arsenic

Abstract

Novel polynuclear iron carbonyl complexes have been isolated from the reactions between the iron carbonyls and the ligands DC=CD(CF2),CF2 ( D = As(CH3j2, n = 1, ffars; D = (C6HB)LP, n = 2, fefos). The complexes have been found to possess the stoichiometry f f a r~F e s ( C O )~~, ffar~Fe3(CO)~, .4~2(CH3)2CHtFe3(CO)g, and fsfosFel(C0)T and their structures have been investigated using various spectroscopic techniques. Some attempt has been made to assign lines in the complicated MOSSbauer spectra of ffarsFes(C0)Q and A s~( C H~)~C H~F~~( C O )~.

The Preparation of Iron Carbonyl Complexes of Fluorocarbon-Bridged Ligands

“…Tables 5-7 also include bare details of previously unpublished experiments involving the symmetrical ligands f,fars, f4fos, and f,fos. No new techniques were used, most separations being made by chromatography on Florisil (1)(2)(3). Qualitative analyses were made by spectroscopic means.…”

“…A number of iron carbonyl derivatives of fluorocarbon-bridged ditertiary arsines and phosphines have been described in recent years (1)(2)(3)(4). Of special interest have been the complexes formed by f4fars and f4fos la and lb.…”

“…The 1 a L = (CH,),As = L' , n = 4, f,fars b L = (C6H5),P = L', n = 4, f4fos c L = (CH,),As, L' = (C6H5),P, n = 4, f4AsP d L = (CH,),As, L' = (C6H5),P, n = 6, f6AsP e L = (C6H5),P = L', n = 6, f6fos f L = (C6H5),P = L', n = 8, f,fos former has the ability to displace two terminal carbonyl groups from Fe,(CO),, to give the complex f4farsFe,(CO),,, 2, (L' = (CH,),As) (3,5). Furthermore, this Fe,(CO),, derivative on mild heating breaks down to a complex of formula f,farsFe,(CO), in which the ligand has undergone rearrangement 3 (L' = (CH,),As) (3,6). Complexes of these types are not formed by f4fos or by related ditertiary phosphines with larger bridging fluoroalicyclic groups.…”

A Kinetic Study of the Thermal Isomerization of and Related Complexes

“…The structure of the product of formula "f,fars"Fe,(CO), is shown in Fig. 1 (3,4). This was an early example of a ligand cleavage reaction.…”

“…For example, in f,farsFe,(CO),, the ligand bridges the two equivalent iron atoms which are also bridged by two CO and an Fe(CO), moiety (2,3). This particular complex on warming undergoes a rearrangement with cleavage of an As-cyclobutene bond and formation of a new Fe-cyclobutene bond.…”