eta(1)-Bound 2-pyrone complexes of molybdenum and iron: A synthetic and structural study

TY - JOUR

T1 - eta(1)-Bound 2-pyrone complexes of molybdenum and iron: A synthetic and structural study

AU - Fairlamb, I J S

AU - Lynam, J M

AU - Taylor, I E

AU - Whitwood, A C

PY - 2004/10/11

Y1 - 2004/10/11

N2 - Oxidative cleavage of the [Mo(CO)(3)(eta(5)-C5H5)](2) with AgBF4 in the presence of 4-methoxy-6-methyl-2-pyrone or 3-bromo-4-methoxy-6-methyl-2-pyrone results in the formation of [Mo(CO)(3)(eta(5)-C5H5){eta(1)(O)-O=COCMe=CHC(OMe)=CH}][BF4] and [Mo(CO)(3)(eta(5)-C5H5){eta(1)(O)-O=COCMe=CHC(OMe)=CBr}][BF4], respectively. Single-crystal X-ray diffraction studies have demonstrated that the orientation of the 2-pyrone ligands varies markedly within the two complexes. In the case of the 4-methoxy-6-methyl-2-pyrone complex the pyrone unit lies parallel to the Mo-CO axis, whereas the bromo-substituted pyrone lies in a perpendicular orientation. Similarly, reactions of [Fe(CO)(2)(eta(5)-C5H5)](2) with AgBF4 in the presence of 4-methoxy-6-methyl-2-pyrone or 3-bromo-4-methoxy-6-methyl-2-pyrone result in formation of [Fe(CO)(2)(eta(5)-C5H5){eta(1)(O)-COCMe=CHC(OMe)=CH}][BF4] and [Fe(CO)(2)(eta(5)-C5H5){eta(1)(O)-COCMe=CHC(OMe)=CBr}][BF4], respectively. Whereas the orientations of the pyrone ligands in the molybdenum and iron complexes containing the brominated 2-pyrone ligands are identical, the iron complex containing the 4-methoxy-6-methyl-2-pyrone contains three cations in the asymmetric unit, two of which have the 2-pyrone ligand perpendicular to the Cp(centroid)-Fe axis, whereas the third unit is parallel. The 2-pyrone ligands of these cations form a stack in which the parallel unit is sandwiched between the two with a perpendicular orientation. The pyrone ligands appear to be only weakly coordinated to the metals and solutions of the complexes rapidly decompose. The complex [Mo(CO)(3)(eta(5)-C5H5){eta(1)(O)-O=COCMe=CHC(OMe)=CH}][BF4] reacts with PhCdropCPh to give [Mo(CO)(eta(2)-PhCdropCPh)(2)(eta(5)-C5H5)][BF4]

AB - Oxidative cleavage of the [Mo(CO)(3)(eta(5)-C5H5)](2) with AgBF4 in the presence of 4-methoxy-6-methyl-2-pyrone or 3-bromo-4-methoxy-6-methyl-2-pyrone results in the formation of [Mo(CO)(3)(eta(5)-C5H5){eta(1)(O)-O=COCMe=CHC(OMe)=CH}][BF4] and [Mo(CO)(3)(eta(5)-C5H5){eta(1)(O)-O=COCMe=CHC(OMe)=CBr}][BF4], respectively. Single-crystal X-ray diffraction studies have demonstrated that the orientation of the 2-pyrone ligands varies markedly within the two complexes. In the case of the 4-methoxy-6-methyl-2-pyrone complex the pyrone unit lies parallel to the Mo-CO axis, whereas the bromo-substituted pyrone lies in a perpendicular orientation. Similarly, reactions of [Fe(CO)(2)(eta(5)-C5H5)](2) with AgBF4 in the presence of 4-methoxy-6-methyl-2-pyrone or 3-bromo-4-methoxy-6-methyl-2-pyrone result in formation of [Fe(CO)(2)(eta(5)-C5H5){eta(1)(O)-COCMe=CHC(OMe)=CH}][BF4] and [Fe(CO)(2)(eta(5)-C5H5){eta(1)(O)-COCMe=CHC(OMe)=CBr}][BF4], respectively. Whereas the orientations of the pyrone ligands in the molybdenum and iron complexes containing the brominated 2-pyrone ligands are identical, the iron complex containing the 4-methoxy-6-methyl-2-pyrone contains three cations in the asymmetric unit, two of which have the 2-pyrone ligand perpendicular to the Cp(centroid)-Fe axis, whereas the third unit is parallel. The 2-pyrone ligands of these cations form a stack in which the parallel unit is sandwiched between the two with a perpendicular orientation. The pyrone ligands appear to be only weakly coordinated to the metals and solutions of the complexes rapidly decompose. The complex [Mo(CO)(3)(eta(5)-C5H5){eta(1)(O)-O=COCMe=CHC(OMe)=CH}][BF4] reacts with PhCdropCPh to give [Mo(CO)(eta(2)-PhCdropCPh)(2)(eta(5)-C5H5)][BF4]

KW - COORDINATED LIGANDS

KW - MOLECULAR-STRUCTURE

KW - CRYSTAL-STRUCTURES

KW - PI-COMPLEXES

KW - DICARBONYLCYCLOPENTADIENYLIRON COMPLEXES

KW - ENANTIOCONTROLLED SYNTHESIS

KW - ENANTIOSPECIFIC SYNTHESIS

KW - CHIRAL SCAFFOLDS

KW - METAL-COMPLEXES

KW - FUNCTIONALIZATION

U2 - 10.1021/om049523w

DO - 10.1021/om049523w

M3 - Article

SN - 0276-7333

VL - 23

SP - 4964

EP - 4969

JO - Organometallics

JF - Organometallics

IS - 21

ER -