Alkynyl gold(I) metallaligands [(AuC-Cbpyl)2(m-diphosphine)] (bpyl=2,2'-bipyridin-5-yl; diphosphine=Ph2P-(CH2)nPPh2, [n=3 (LPr), 4 (LBu), 5 (LPent), 6 (LHex)], dppf (LFc), Binap (LBinap) and Diop (LDiop)) react with MX2 (M=Fe, Zn, X= ClO4; M=Co, X=BF4) to give triple helicates [M2(LR)3]X4. These complexes, except those containing the semirigid LBinap metallaligand, present similar hydrodynamic radii (determined by diffusion NMR spectroscopy measurements) and a similar pattern in the aromatic region of their 1H NMR spectra, which suggests that in solution they adopt a compact structure where the long and flexible organometallic strands are folded. The diastereoselectivity of the self-assembly process was studied by using chiral metallaligands, and the absolute configuration of the iron(II) complexes with LBinap and LDiop was determined by circular dichroism spectroscopy (CD). Thus, (R)-LBinap or (S)-LBinap specifically induce the formation of (D,D)-[Fe2((R)-LBinap)3](ClO4)4 or (L,L)-[Fe2((S)-LBinap)3](ClO4)4, respectively, whereas (R,R)-or (S,S)-LDiop give mixtures of the DD-and LL-diastereomers. The DD helicate diastereomer is dominant in the reaction of FeII with (R,R)-LDiop, whereas the LL isomer predominates in the analogous reaction with (S,S)-LDiop. The photophysical properties of the new dinuclear alkynyl complexes and the helicates have been studied. The new metallaligands and the [Zn2(LR)3]4+ helicates present luminescence from [p!p] excited states mainly located in the C-Cbpyl units.
Triple helicates with golden strands: Self-assembly of M2Au 6 complexes from gold(I) metallaligands and iron(II), cobalt(II) or zinc(II) cations
MASCIOCCHI, NORBERTO;
2014-01-01
Abstract
Alkynyl gold(I) metallaligands [(AuC-Cbpyl)2(m-diphosphine)] (bpyl=2,2'-bipyridin-5-yl; diphosphine=Ph2P-(CH2)nPPh2, [n=3 (LPr), 4 (LBu), 5 (LPent), 6 (LHex)], dppf (LFc), Binap (LBinap) and Diop (LDiop)) react with MX2 (M=Fe, Zn, X= ClO4; M=Co, X=BF4) to give triple helicates [M2(LR)3]X4. These complexes, except those containing the semirigid LBinap metallaligand, present similar hydrodynamic radii (determined by diffusion NMR spectroscopy measurements) and a similar pattern in the aromatic region of their 1H NMR spectra, which suggests that in solution they adopt a compact structure where the long and flexible organometallic strands are folded. The diastereoselectivity of the self-assembly process was studied by using chiral metallaligands, and the absolute configuration of the iron(II) complexes with LBinap and LDiop was determined by circular dichroism spectroscopy (CD). Thus, (R)-LBinap or (S)-LBinap specifically induce the formation of (D,D)-[Fe2((R)-LBinap)3](ClO4)4 or (L,L)-[Fe2((S)-LBinap)3](ClO4)4, respectively, whereas (R,R)-or (S,S)-LDiop give mixtures of the DD-and LL-diastereomers. The DD helicate diastereomer is dominant in the reaction of FeII with (R,R)-LDiop, whereas the LL isomer predominates in the analogous reaction with (S,S)-LDiop. The photophysical properties of the new dinuclear alkynyl complexes and the helicates have been studied. The new metallaligands and the [Zn2(LR)3]4+ helicates present luminescence from [p!p] excited states mainly located in the C-Cbpyl units.
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