Inversion of configuration around the seven-coordinated cobalt center induced by an interaction between sugars and tetrahedral oxoanions

Tanase, Tomoaki; Nakagoshi, Masako; Teratani, Akemi; Kato, Masako; Yamamoto, Yasuhiro; Yano, Shigenobu

doi:10.1021/ic00079a003

Cited by 22 publications

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“…The vicinal functional groups feature several donor atoms capable of forming stable complexes with transition metals [7] and offer several possibilities to introduce additional donor groups into the sugar backbone. Well-known modification strategies are N-glycosylation of polyamines [8,9] and nucleophilic substitution of bromoethyl-O-glycosides. [10] TEMPO oxidation of the secondary hydroxyl group at C6 results in the formation of uronic acids.…”

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confidence: 99%

Hydrogen Bonds as Structural Directive towards Unusual Polynuclear Complexes: Synthesis, Structure, and Magnetic Properties of Copper(II) and Nickel(II) Complexes with a 2‐Aminoglucose Ligand

Burkhardt

Spielberg

Simon

et al. 2009

Chemistry A European J

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The reaction of benzyl 2-amino-4,6-O-benzylidene-2-deoxy-alpha-D-glucopyranoside (HL) with the metal salts Cu(ClO(4))(2)6 H(2)O and Ni(NO(3))(2)6 H(2)O affords via self-assembly a tetranuclear mu(4)-hydroxido bridged copper(II) complex [(mu(4)-OH)Cu(4)(L)(4)(MeOH)(3)(H(2)O)](ClO(4))(3) (1) and a trinuclear alcoholate bridged nickel(II) complex [Ni(3)(L)(5)(HL)]NO(3) (2), respectively. Both complexes crystallize in the acentric space group P2(1). The X-ray crystal structure reveals the rare (mu(4)-OH)Cu(4)O(4) core for complex 1 which is mu(2)-alcoholate bridged. The copper(II) ions possess a distorted square-pyramidal geometry with an [NO(4)] donor set. The core is stabilized by hydrogen bonding between the coordinating amino group of the glucose backbone and the benzylidene protected oxygen atom O4 of a neighboring {Cu(L)} fragment as hydrogen-bond acceptor. For complex 2 an [N(4)O(2)] donor set is observed at the nickel(II) ions with a distorted octahedral geometry. The trinuclear isosceles Ni(3) core is bridged by mu(3)-alcoholate O3 oxygen atoms of two glucose ligands. The two short edges are capped by mu(2)-alcoholate O3 oxygen atoms of the two ligands coordinated at the nickel(II) ion at the vertex of these two edges. Along the elongated edge of the triangle a strong hydrogen bond (244 pm) between the O3 oxygen atoms of ligands coordinating at the two relevant nickel(II) ions is observed. The coordinating amino groups of the these two glucose ligands are involved in additional hydrogen bonds with O4 oxygen atoms of adjacent ligands further stabilizing the trinuclear core. The carbohydrate backbones in all cases adopt the stable (4)C(1) chair conformation and exhibit the rare chitosan-like trans-2,3-chelation. Temperature dependent magnetic measurements indicate an overall antiferromagnetic behavior for complex 1 with J(1)=-260 and J(2)=-205 cm(-1) (g=2.122). Compound 2 is the first ferromagnetically coupled trinuclear nickel(II) complex with J(A)=16.4 and J(B)=11.0 cm(-1) (g(1,2)=2.183, g(3)=2.247). For the high-spin nickel(II) centers a zero-field splitting of D(1,2)=3.7 cm(-1) and D(3)=1.8 cm(-1) is observed. The S=3 ground state of complex 2 is consistent with magnetization measurements at low temperatures.

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Hydrogen Bonds as Structural Directive towards Unusual Polynuclear Complexes: Synthesis, Structure, and Magnetic Properties of Copper(II) and Nickel(II) Complexes with a 2‐Aminoglucose Ligand

Burkhardt

Spielberg

Simon

et al. 2009

Chemistry A European J

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“…In general, the absolute configuration around the metal center (configurational effect) has the major contribution to the circular dichroism rather than the minor contributions of the chelate ring conformation (confonnational effect) and the chiral centers on the ligands (vicinal effect). Thus, the opposite sign between 1 and 2-3 was tentatively atmbuted to an inversion of the absolute configuration around the (4).3d Contrary, in the A configuration, the five-membered chelate rings of the sugar moieties are nearly parallel to the C3 axis (Zel form) and the hydrogen bondings could not be expected.…”

Section: Resultsmentioning

confidence: 99%

Intelligent Sugar Complexes

Yano

Nakagoshi

Teratani

et al. 1996

Molecular Crystals and Liquid Crystals Science and Technology.

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“…To the best of our knowledge complex [Ni(Hsal HMan)(tptz)]ClO 4 is the first transition metal complex exhibiting a non-chair conformation of a mannopyranose ring. In transition metal complexes derived from mannose or the related L L-rhamnose, containing more flexible co-ligand moieties like (aminoalkyl)amines [48][49][50][51][52][53] instead of the rigid tptz molecule or obtained from less donor-functionalized sugar moieties, 54-57 the pyranose ring generally adopts the expected chair conformation.…”

Section: Pyranose Ring Conformationmentioning

confidence: 99%

Nickel(II) complexes with Schiff-base ligands derived from epimeric pyranose backbones as 2,3-chelators: modeling the coordination chemistry of chitosan

Burkhardt

Görls

Plass

2008

Carbohydrate Research

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Inversion of configuration around the seven-coordinated cobalt center induced by an interaction between sugars and tetrahedral oxoanions

Cited by 22 publications

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Hydrogen Bonds as Structural Directive towards Unusual Polynuclear Complexes: Synthesis, Structure, and Magnetic Properties of Copper(II) and Nickel(II) Complexes with a 2‐Aminoglucose Ligand

Hydrogen Bonds as Structural Directive towards Unusual Polynuclear Complexes: Synthesis, Structure, and Magnetic Properties of Copper(II) and Nickel(II) Complexes with a 2‐Aminoglucose Ligand

Intelligent Sugar Complexes

Nickel(II) complexes with Schiff-base ligands derived from epimeric pyranose backbones as 2,3-chelators: modeling the coordination chemistry of chitosan

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