(−)<sub>545</sub>-<i>fac</i>-Δ-Tris(<scp>L</scp>-prolinato)cobalt(III) trihydrate

Kato, Masaru; Hayashi, Miho; Fujihara, Takashi; Nagasawa, Akira

doi:10.1107/s1600536808010246

Cited by 4 publications

(6 citation statements)

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“…It is known that proline can form stable octahedral anionic complexes with Ni and a stabilizing countercation 56 with a similar structure to that of Co(prolinate) 3 . 57 In each of these complexes, each proline ligand is coordinated to the central metal ion via the lone pair of electrons on the NH species and an O atom of the O−CO functionality. The six chelating atoms adopt an octahedral environment around the central ion.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…57 In each of these complexes, when describing the 3-D structures of these complexes is that although, for example, the Δ-facand Λ-fac-isomers are mirror images in terms of the chelating atoms, the chirality of the proline ligands removes the mirror relationship between the two isomers. Furthermore, in the gas phase, an isolated proline molecule can exist as either cis-or trans-isomers; in the trans-isomer the carboxylic acid moiety is in the same plane as the pyrrolidine ring, whereas in the trans-isomer they are in different planes.…”

Section: Dftmentioning

confidence: 99%

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Formation of Bioinorganic Complexes by the Corrosive Adsorption of (S)-Proline on Ni/Au(111)

et al. 2014

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Nickel nanoparticles modified by the adsorption of chiral amino acids are known to be effective enantioselective heterogeneous catalysts. The leaching of nickel by amino acids has a number of potential effects including the induction of chirality in the nickel atoms left behind in the nanoparticle and the creation of catalytically active nickel complexes. The adsorption of (S)-proline onto Au(111) precovered by two dimensional nickel nanoclusters was investigated by scanning tunnelling microscopy, X-ray photoelectron spectroscopy and high resolution electron energy loss spectroscopy. Adsorption of (S)-proline at 300 K resulted in the corrosion of the nickel clusters, the oxidation of the leached nickel and the on-surface formation of bioinorganic complexes, which are concluded to contain three prolinate species in an 2 octahedral arrangement around the central Ni ion. Two distinguishable forms of nickel prolinate complexes were identified. One form self-assembles into 1-D chains and the other form gives rise to porous 2-D islands. Octahedral complexes of the type M(AB) 3 are intrinsically chiral resulting in two pairs of enantiomers. The mirror symmetry of each pair of enantiomers is broken when, as in this study, the bidentate ligand itself possesses a chiral center. DFT calculations are used to examine the relative energies of each Ni(prolinate) 3 complex as isolated gas phase species and isolated adsorbed species.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Dftmentioning

confidence: 99%

Formation of Bioinorganic Complexes by the Corrosive Adsorption of (S)-Proline on Ni/Au(111)

et al. 2014

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“…In addition, we compare the binuclear complex 1 with the corresponding mononuclear analogue: (À) 545 -fac-D-tris-(S-prolinato)cobalt(III)-Co(S-Pro) 3 38,39 (2) taking under consideration also circular dichroism (CD) spectra. In this paper we also describe synthesis of 1 and report X-ray structure of its tetrahydrate.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, structure, circular dichroism of a Δ(−)546-di-μ-hydroxo-tetrakis(S-prolinato)dicobalt(iii) complex and NMR study of its interaction with chiral and non-chiral probes in solutions

et al. 2012

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Slow oxidation of cobalt(II) ions by aerial oxygen in the presence of S-prolinate led to isolation of a new m-OH bridged binuclear chiral complex of cobalt(III): Co 2 (m-OH) 2 (S-Pro) 4 . The X-ray structure of this compound was studied. Co III ions are located in N 2 O 4 donor sets containing N and O atoms of S-prolinates at trans(N), cis(O)-or cis(N), trans(O)-positions. Optical properties of Co 2 (m-OH) 2 (S-Pro) 4 were investigated by means of electronic and circular dichroism spectroscopy providing data for comparison with the corresponding mononuclear complex of S-prolinate, cis-(À)-Co(S-Pro) 3 , as well as with other previously reported m-OH bridged cobalt(III) complexes. CD spectra also confirmed that no racemization of S-prolinate occurred during synthesis. The solution behaviour of Co 2 (m-OH) 2 (S-Pro) 4 in the presence of various organic acids was studied by 1 H and 13 C NMR techniques evidencing specific interactions between carboxylic groups of the substrate and hydrogen-bonding groups of the Co 2 (m-OH) 2 (S-Pro) 4 molecule. Relying on the NMR spectroscopy results, the most probable models of binding between Co 2 (m-OH) 2 (S-Pro) 4 and S-proline as well as N-benzoylated a-amino acids were discussed. Chart 1 Simplified representation of the most stable ligand configuration in M 2 (m-OH) 2 (S-Pro) 4 (M = Cr III reported by Oki et al., 33 M = Co III in this publication).

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“…Another crystal comprising isolated units is the L-prolinate of Co 3+ , namely, tris (L-prolinato)-cobalt trihydrate (Kato et al 2008). In this species, the same motif as in tris(glycinato)-cobalt monohydrate and tris(L-alaninato)-cobalt monohydrate is found: Three bidentate (N,O)-prolinate anions form an octahedral [6]-coordination around the cation (compare with Fig.…”

Section: Valine Leucine and Isoleucinementioning

confidence: 82%

Compounds of Amino Acids as Anions

Fleck

Petrosyan

2014

Salts of Amino Acids

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This chapter deals with salts formed from metal cations and amino acid anions. All amino acids can act as monovalent anion; the acidic members glutamic acid and aspartic acid as well as cysteine and tyrosine can form both monovalent and divalent anions. Due to the large number of available cations, a multitude of combinations is possible and in fact found (for the standard twenty amino acids, over 150 crystal structures are published, and many more species have been characterized by other methods). Different hydration states (as reported for the pristine amino acid crystals) occur as well, and the existence of polymorphs is also documented for some cases. The formation of metal-amino acid complexes has been studied in several works (both for a given amino acid and a given cation), and the flexibility of amino acid molecules as ligands allows coordination of cations with different chemical properties (such as charge or ionic radius). Several coordination modes are found for amino acids -the molecules can act as monodentate, bidentate, tridentate, and bridging ligands. The connectivity of the coordination polyhedra of the metal cations is considered -isolated units are frequent, but chains and layers occur as well. Moreover, these units can connect via amino acid molecules to form higher-dimensional structures. Hydrogen bonds (also involving water molecules, both in coordination or in the interstices as crystal water) further stabilize the units, forming relatively stable phases. The frequency of salts varies among the different amino acids, and most examples are reported for glycinate salts, whereas crystals of cations and basic and weakly soluble amino acids are difficult to obtain (e.g., arginate and lysinate salts have not been reported in crystalline state). Finally, the aspect of symmetry is considered (the chirality of most amino acids playing a crucial role), and, consequently, the properties of these salts have impact on applications in the fields of physics, biology, and medicine.

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(−)₅₄₅-fac-Δ-Tris(L-prolinato)cobalt(III) trihydrate

Abstract: The absolute configuration of the octahedral fac-CoN3O3 title complex, [Co(C5H8NO2)3]·3H2O, has been determined by single-crystal X-ray analysis. A three-dimensional network of hydrogen bonds is observed between the proline carboxylate groups and the three uncoordinated water molecules.

Cited by 4 publications

References 4 publications

Formation of Bioinorganic Complexes by the Corrosive Adsorption of (S)-Proline on Ni/Au(111)

Formation of Bioinorganic Complexes by the Corrosive Adsorption of (S)-Proline on Ni/Au(111)

Synthesis, structure, circular dichroism of a Δ(−)546-di-μ-hydroxo-tetrakis(S-prolinato)dicobalt(iii) complex and NMR study of its interaction with chiral and non-chiral probes in solutions

Compounds of Amino Acids as Anions

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(−)545-fac-Δ-Tris(L-prolinato)cobalt(III) trihydrate

Cited by 4 publications

References 4 publications

Formation of Bioinorganic Complexes by the Corrosive Adsorption of (S)-Proline on Ni/Au(111)

Formation of Bioinorganic Complexes by the Corrosive Adsorption of (S)-Proline on Ni/Au(111)

Synthesis, structure, circular dichroism of a Δ(−)546-di-μ-hydroxo-tetrakis(S-prolinato)dicobalt(iii) complex and NMR study of its interaction with chiral and non-chiral probes in solutions

Compounds of Amino Acids as Anions

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(−)₅₄₅-fac-Δ-Tris(L-prolinato)cobalt(III) trihydrate