Synthesis and characterization of [(CO)4FeL-L] and [(CO)4FeL-LFe(CO)4] wherein L-L is N(CH2CH2)3N and also P(NMeNMe)3P in the latter complex: single crystal X-ray molecular structure of [Fe(CO)4DABCO

Robson M Matos,John G Verkade

doi:10.1590/s0103-50532003000100012

Abstract

Herein we report the syntheses and characterization of the novel title mono- and dinuclear compounds from pentacarbonyliron. They were obtained in a stepwise manner by UV irradiation of [Fe(CO)5] with the appropriate ligand in THF and were characterized by ¹H, 13C, 13C{¹H} 31P and 31P{¹H} NMR spectroscopy, by IR spectroscopy and by elemental analysis. The single crystal X-ray molecular structure of [Fe(CO)4(DABCO)] is described. The 13C{¹H} NMR spectra of each of the title complexes reveal their fluxional behavior, which presumably occurs via Berry pseudorotation.

Highlights

With the exception of nitrosyl complexes, mononuclear iron tetracarbonyl complexes bearing nitrogen ligands are relatively rare[1] and most of the reported examples involve aromatic nitrogen ligands such as pyridine,[2,3,4,5] picoline,[2] pyrazine,[3] quinoline[2] and lutidine.[2]
Several aliphatic trialkylaminetetracarbonyl iron complexes have been reported in which the ligand is NMe3,6,7 NEt3,6 n-NPr3,6 nNBu3,6 N(PhCH2)2Me,[6] hexamethylenetetraamine[6] or quinuclidine.[6]
The instability of aminetetracarbonyl iron complexes has been attributed to the tendency of nitrogen bases to facilitate disproportionation of iron pentacarbonyl.[4,8,9,10,11]

Summary

Introduction

With the exception of nitrosyl complexes, mononuclear iron tetracarbonyl complexes bearing nitrogen ligands are relatively rare[1] and most of the reported examples involve aromatic nitrogen ligands such as pyridine,[2,3,4,5] picoline,[2] pyrazine,[3] quinoline[2] and lutidine.[2]. The mixture was irradiated for 48 h and the solvent was evaporated under reduced pressure to dryness to yield a red solid that was purified chromatographically on Florisil using acetonitrile as eluent. The mixture 5 was irradiated with UV light for 4 h and unreacted [Fe(CO)5] and the solvent were evaporated under reduced pressure to dryness, affording a pale yellow solid that was purified by chromatography on Florisil using benzene as eluent.

Results

Conclusion