X-ray crystal comparisons and rates of conversion between RS/SR and RR/SS-[Ni(n-PrAO)2–H]+

Murmann, R. Kent; Barnes, Charles L.; Barakat, Samuel

doi:10.1016/s0277-5387(00)00644-6

Cited by 5 publications

(5 citation statements)

References 13 publications

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“…C 16 COO ]-ClO 4 ·0.5CH 3 OH (7·0.5CH 3 OH) were covered by paraffin oil and mounted on a glass fiber. Cu(ClO 4 ) 2 ·6H 2 O (11.1 mg, 0.03 mmol) in methanol (0.2 mL) was then added at room temperature.…”

Section: Homochiral-[(cul Coo )Clo 4 ] N (7)mentioning

confidence: 99%

“…[12][13][14][15][16][17][18][19] Several other strategies investigated included the synthesis of compounds that have a stereogenic nitrogen atom by freezing the nitrogen lone pair inversion. [12][13][14][15][16][17][18][19] Several other strategies investigated included the synthesis of compounds that have a stereogenic nitrogen atom by freezing the nitrogen lone pair inversion.…”

Section: Introductionmentioning

confidence: 99%

“…The solution was allowed to stand at 5°C to afford single16.5 H 20 ClCuN 3 O 7.5 ([CuL COO ]ClO 4 ·0.5CH 3 OH): calcd. After a while, a precipitate appeared and was collected and recrystallized from acetonitrile in the presence of NaClO 4 ·H 2 O (4.2 mg, 0.03 mmol) to afford single crystals of 1.…”

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confidence: 99%

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Differentiation of Oxygen Atom Chirality in Copper(II) Complexes with Dipicolylamine‐Derived Ligands

et al. 2012

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The ether coordination of the oxygen atom to the copper(II) center supported by dipicolylamine (DPA)‐derived ligands,N‐[2‐(2‐pyridylmethyloxy)ethyl]‐N,N‐bis(2‐pyridylmethyl)amine (LPy), N‐[2‐(2‐quinolylmethyloxy)ethyl]‐N,N‐bis(2‐pyridylmethyl)amine (LQ), N‐[3‐(2‐pyridylmethyloxy)‐1‐propyl]‐N,N‐bis(2‐pyridylmethyl)amine (L′Py), N‐{2‐[1‐(2‐pyridyl)ethyloxy]ethyl}‐N,N‐bis(2‐pyridylmethyl)amine (LPy*1), N‐[2‐(2‐pyridylmethyloxy)‐1‐propyl]‐N,N‐bis(2‐pyridylmethyl)amine (LPy*2), and N‐[2‐(carboxymethyloxy)ethyl]‐N,N‐bis(2‐pyridylmethyl)amine (HLCOO), have been examined. The factors that facilitate the coordination of the ether oxygen atom of these ligands to the copper center and the control of chirality around the copper‐coordinated oxygen atom are discussed. The copper center exhibits a pentacoordinate geometry with these ligands, as evidenced by X‐ray crystallography. The steric effect of the quinoline ring in the LQ complex prevents the coordination of a perchlorate anion to the copper center, which affords the pentacoordinate divalent complex with a shorter copper–oxygen bond than that for the corresponding pyridine ligand (LPy). The six‐membered chelate in the L′Py complex also exhibits a shorter Cu–O distance. The conformation of the oxygen atom of the LPy complex is unstable because of fast lone pair inversion, but this inversion is prevented for the complexes with chiral ligands, LPy*1 and LPy*2. Upon chelation to the metal center, the HLCOO ligand forms a pentacoodinate monomer complex that further affords a 1‐D polymer structure. With respect to the oxygen chirality, the water content of the solvent governs the formation of either a homochiral polymer (R‐R‐R‐R‐ or S‐S‐S‐S‐) or an alternative chirality polymer (R‐S‐R‐S‐). In this case, the isomers with respect to the oxygen chirality were separated and characterized.

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Section: Homochiral-[(cul Coo )Clo 4 ] N (7)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Differentiation of Oxygen Atom Chirality in Copper(II) Complexes with Dipicolylamine‐Derived Ligands

et al. 2012

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“…It is well-known that a nitrogen lone pair inverts via pyramidal inversion, , causing expeditious loss of chirality at a stereogenic nitrogen center. Thus, asymmetric nitrogen atoms that have been characterized have been limited to a series of quaternary ammonium ions , and N -oxides, , protonated , or metal-coordinated − amine ligands, and free tertiary amines with adequate electronic and structural , restrictions. Among them, asymmetric nitrogen atoms coordinated to metal centers are of particular interest as the chirality exists in the primary coordination sphere of the metal ion, potentially influencing the physical and chemical properties of the metal center .…”

Section: Introductionmentioning

confidence: 99%

Novel Oxygen Chirality Induced by Asymmetric Coordination of an Ether Oxygen Atom to a Metal Center in a Series of Sugar-Pendant Dipicolylamine Copper(II) Complexes

et al. 2006

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Six sugar-pendant 2,2'-dipicolylamine (DPA) ligands (L1-3 and L'1-3) have been prepared. OH-protected and unprotected D-glucose, D-mannose, and D-xylose were attached to a DPA moiety via an O-glycoside linkage. X-ray crystallography of the copper(II) complexes (1-5) with these ligands revealed that the anomeric oxygen atom is coordinated to the metal center in the solid state, generating a chiral center at the oxygen atom. The CD spectra of these copper complexes in methanol or aqueous solution exhibit Cotton effects in the d-d transition region, which indicates that the ether oxygen atoms remain coordinated to the metal center and the oxygen-atom chirality is preserved even in solution. For complexes 1 and 2, the inverted oxygen-atom chirality and chelate-ring conformation in the solid state are well correlated with the mirror-image CD spectra in methanol solution. The concomitant inversion of the asymmetric configuration around the copper center was also observed in a methanol solution of complex 3 and a pyridine solution of complex 2. The square-pyramidal/octahedral copper(II) centers also exhibited characteristic absorption and CD spectra.

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“…This chirality would normally be unstable because the lone pair on the oxygen atom inverts via pyramidal inversion in a similar manner with the nitrogen atom of aliphatic amines (Scheme a). In the case of nitrogen, however, this inversion can be substantially retarded on the metal ion coordination at the nitrogen atom, and the structure of asymmetric nitrogen and its inversion kinetics are extensively demonstrated in cobalt(III)−, nickel(II)−, platinum(II)−, and copper(II)−amine complexes. Thus, to synthesize the complexes that exhibit a chiral center at the oxygen atom, not only does strong coordination between ether oxygen atom and metal ion differentiate two lone pairs on the oxygen atom, but also adequate control of the configuration of the oxygen substituents is necessary.…”

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confidence: 99%

Control of Oxygen Atom Chirality and Chelate Ring Conformation by Protected/Free Sugar Hydroxyl Groups in Glucose-Pendant Dipicolylamine−Copper(II) Complexes

2004

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A pair of copper(II) complexes 1 and 2 exhibit an enantiomeric chiral center at the oxygen atom that coordinates to the metal center. The configurations of the oxygen atom chirality and the chelate ring conformation are simply controlled by protected/free hydroxyl groups of the sugar moiety, yielding mirror image CD spectra. In this system, repulsive and attractive forces are used to regulate chirality on the copper-coordinated oxygen atom both in the solid state and in solution.

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X-ray crystal comparisons and rates of conversion between RS/SR and RR/SS-[Ni(n-PrAO)2–H]+

Cited by 5 publications

References 13 publications

Differentiation of Oxygen Atom Chirality in Copper(II) Complexes with Dipicolylamine‐Derived Ligands

Differentiation of Oxygen Atom Chirality in Copper(II) Complexes with Dipicolylamine‐Derived Ligands

Novel Oxygen Chirality Induced by Asymmetric Coordination of an Ether Oxygen Atom to a Metal Center in a Series of Sugar-Pendant Dipicolylamine Copper(II) Complexes

Control of Oxygen Atom Chirality and Chelate Ring Conformation by Protected/Free Sugar Hydroxyl Groups in Glucose-Pendant Dipicolylamine−Copper(II) Complexes

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