Iron complexes of facially capping triphosphorus macrocycles.
Primary and secondary phosphine piano-stool complexes of the type [eta(5)-CpFeL3]+ (L = phenylphosphine, 3, (alpha-methyl)vinylphosphine, 4, allylphosphine, 5, (2-methylpropenyl)phosphine, 5b, allyl(phenyl)phosphine, 6) are described. The alkenyl phosphine complexes, 5 and 6, react by intramolecular hydrophosphination to give the corresponding [eta(5)-CpFe]+ complexes of 1,5,9-triphosphacyclododecane (12-aneP3R3, 2, R = H), 9 and 10 respectively. Alkylation of the secondary phosphines in 9 is achieved by hydrophosphinations with ethene to give the 12-aneP3R3 (R = Et) derivative 11. These complexes are also obtained by reaction of suitable [eta(5)-CpFe]+ containing precursor complexes with the corresponding free 12-aneP3R3 macrocycle as is the related [eta(5)-Cp*Fe]+ derivative, 8. Direct substitution of acetonitrile in [Fe(CH3CN)6][BF4]2 by 12-aneP3Et3, leads to the macrocycle piano-stool complex, [(12-aneP3Et3)Fe(CH3CN)3][BF4]2, 7. The crystal structures of selected primary phosphine, eta(5)-Cp, eta(5)-Cp* complexes and 7, allow a comparison of steric influences upon key macrocycle ring closure reactions and hence an insight into parameters required for the formation of smaller ring sizes by template based methods.
Edwards
Peter G
PG
School of Chemistry, Cardiff University, Cardiff, UKCF10 3AT. Edwardspg@cardiff.ac.uk
Malik
K M Abdul
KM
Ooi
Li-ling
LL
Price
Andrew J
AJ