TY - JOUR
T1 - Reductive coupling of [(RO) 2Ti(L 2) 2] complexes containing a chelating bis(aryloxide) ligand with ketones (L 2 = bpy, dmbpy, or phen)
AU - Owiny, David
AU - Kingston, Jesudoss V.
AU - Maynor, Marc
AU - Parkin, Sean
AU - Kampf, Jeff W.
AU - Ladipo, Folami T.
PY - 2005/8/1
Y1 - 2005/8/1
N2 - The reactivity of [(RO) 2Ti(L 2) 2] complexes (L 2 = bpy, dmbpy, or phen; (RO) 2 = DMSC or MBMP) with ketones was investigated (DMSC = 1,2-alternate dimethylsilyl-bridged p-tertbutylcalix[4]arene dianion; MBMP = 2,2′-methylenebis(6-tert-butyl-4- methylphenol) dianion). The molecular structures of [(DMSC)Ti(bpy)2] (6a) and [(DMSC)Ti(bpy) 2] (7a) were characterized by X-ray crystallography. Their structural data taken together with UV-visible and magnetic susceptibility data suggest some electron transfer into the LUMO (π* orbital) of the diimine ligands. [(RO) 2Ti(L 2) 2] complexes undergo light-assisted reaction with aromatic ketones in a reversible manner to afford Ti-η 2-ketone complexes [(RO) 2Ti(η 2-OCArR)(L 2)] (Ar = aryl while R = aryl or alkyl), which undergo further reaction with ketone to give the corresponding 2-aza-5-oxa-titanacyclopentene. Qualitatively, the efficacy of the formation of 2-aza-5-oxa-titanacyclopentene [(RO) 2Ti(L 2) 2] complexes increased with increasing ketone concentration and in the order L 2 = bpy < dmbpy < phen. This order is best explained in terms of the dependence of the equilibrium between [(RO) 2Ti(L 2) 2] and [(RO) 2Ti(η 2-OCArR) (L 2)] on relative abilities of the ketone and the diimine to accept π-electron density, as well as in terms of the order of the rate of reaction of [(RO) 2Ti(η 2-OCArR)(L 2)] with ketone.
AB - The reactivity of [(RO) 2Ti(L 2) 2] complexes (L 2 = bpy, dmbpy, or phen; (RO) 2 = DMSC or MBMP) with ketones was investigated (DMSC = 1,2-alternate dimethylsilyl-bridged p-tertbutylcalix[4]arene dianion; MBMP = 2,2′-methylenebis(6-tert-butyl-4- methylphenol) dianion). The molecular structures of [(DMSC)Ti(bpy)2] (6a) and [(DMSC)Ti(bpy) 2] (7a) were characterized by X-ray crystallography. Their structural data taken together with UV-visible and magnetic susceptibility data suggest some electron transfer into the LUMO (π* orbital) of the diimine ligands. [(RO) 2Ti(L 2) 2] complexes undergo light-assisted reaction with aromatic ketones in a reversible manner to afford Ti-η 2-ketone complexes [(RO) 2Ti(η 2-OCArR)(L 2)] (Ar = aryl while R = aryl or alkyl), which undergo further reaction with ketone to give the corresponding 2-aza-5-oxa-titanacyclopentene. Qualitatively, the efficacy of the formation of 2-aza-5-oxa-titanacyclopentene [(RO) 2Ti(L 2) 2] complexes increased with increasing ketone concentration and in the order L 2 = bpy < dmbpy < phen. This order is best explained in terms of the dependence of the equilibrium between [(RO) 2Ti(L 2) 2] and [(RO) 2Ti(η 2-OCArR) (L 2)] on relative abilities of the ketone and the diimine to accept π-electron density, as well as in terms of the order of the rate of reaction of [(RO) 2Ti(η 2-OCArR)(L 2)] with ketone.
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U2 - 10.1021/om050231k
DO - 10.1021/om050231k
M3 - Article
AN - SCOPUS:23844492853
SN - 0276-7333
VL - 24
SP - 3995
EP - 4002
JO - Organometallics
JF - Organometallics
IS - 16
ER -