Takumi Konno

Metallosupramolecular Structures Derived from a Series of Diphosphine-bridged Digold(I) Metalloligands with Terminal d-Penicillamine

In this report, we describe our recent work on the development of a new family of chiral heteroleptic digold(I) metalloligands with mixed diphosphine and d-penicillaminate (d-pen), [Au2 (dppx)(d-pen-S)2 ](2-) (dppxu2009=u2009PPh2 (CH2 )n PPh2 , nu2009=u20091-5) and their application for the construction of chiral multinuclear and metallosupramolecular structures. The reactions of the metalloligands with 3d metal ions produce a variety of chiral heterobimetallic structures retaining the digold(I) metalloligand structure, ranging from discrete trinuclear to infinite helix structures that depend on the type of dppx. In addition, monophosphine and triphosphine analogues of the metalloligands were designed, and their coordination behavior is discussed to show the essential properties and potential extensibility of this class of metalloligands.

Disproportionation of Achiral Nickel(II) Centers into Two Kinds of Chiral Nickel(II) Centers Caused by an Achiral Diimine Ligand

Since the correlation between molecular structure and optical activity was discovered by Pasteur, chirality has achieved great importance in various research fields, involving chemistry, biochemistry, and materials science. In recent years, chiral coordination compounds have received increased attention because of their potential applications in asymmetric catalysis, nonlinear optics, sensors, and multifunctional materials, as well as due to their fundamental significance in modern stereochemistry. The most representative approach for introducing chirality in coordination compounds is the chelation of three bidentate ligands to a metal center, which gives rise to a metal octahedron with either the D or the L chiral configuration. The use of spatially controlled bridging ligands often generates discrete or infinite coordination compounds that possess righthanded (P) or left-handed (M) helical chirality. In common, a pair of enantiomers is produced by using an achiral ligand unless enantiopure auxiliaries, such as chiral catalysts, templates, and solvents, are involved in the reaction. On the other hand, the introduction of an element of chirality, represented by asymmetric carbon centers with either the R or the S chiral configuration, into the ligand possibly leads to the diastereoselective synthesis of a single optically active isomer. We have been interested in the diastereoselective synthesis of polynuclear and supramolecular coordination compounds by employing chiral sulfurcontaining amino acids, such as cysteine (H2cys) and penicillamine (H2pen). [15–17] Recently, we have shown that a linear Au complex with two d-penicillaminate (d-pen) ligands, [Au ACHTUNGTRENNUNG(d-pen-S)2]3 , acts as a bridging metallo ACHTUNGTRENNUNGli ACHTUNGTRENNUNGgand to produce an S-bridged Au2Ni II 2 tetranuclear complex, [Au2Ni2(d-pen-N,S)4] 2 ([1] ), in which each of the two Ni centers is in an N2S2 square-planar geometry chelated by two d-pen ligands. Although compound [1] was selectively produced under given reaction conditions, we found that [1] interconverts to an S-bridged Au3Ni II 2 pentanuclear complex, [Au3Ni2(dpen-N,S)6] 5 ([2] ), in response to a change in external factors, such as molar ratio, solution pH, solvent, and temperature. Because each Ni center in [2] has an N3S3 octahedral geometry chelated by three d-pen ligands, three diaACHTUNGTRENNUNGstereo ACHTUNGTRENNUNGmers, (DD)2, (DD)(LD), and (LD)2, are possible. However, only the (LD)2 isomer was observed for [2] 5 , implying that the diastereoselective production of a heterometallic multinuclear complex proceeds with the conversion of achiral square-planar Ni centers to chiral octahedral Ni centers. This result suggests that the square-planar Ni centers in [1] could potentially be converted to octahedral Ni centers with retention of the S-bridged Au2Ni II 2 tetranuclear structure, by chelation with an additional bidentate ligand. To confirm this, we investigated the reaction of [1] with 1,10-phenanthroline (phen), which has been recognized as an effective chelating ligand to a Ni center. Remarkably, the reaction resulted in the formation of [2] and [NiACHTUNGTRENNUNG(phen)3]2 , rather than the anticipated Au2Ni2 tetranuclear complex with mixed d-pen and phen ligands. Herein, we report a unique structural conversion induced by an achiral diimine ligand, which results in the disproportionation of achiral Ni centers in [1] to form chiral Ni centers in [2] and [Ni ACHTUNGTRENNUNG(phen)3]2+ (Scheme 1). The production of two kinds of complex salts from the same reaction controlled by solvent polarity, together with the marked difference in their magnetic properties affected by chirality, is presented. The reaction of a red aqueous solution of K2[1] with phen (2 equiv) gave a green solution in a few minutes. After the addition of KCl, the reaction solution was stored in a refrigerator for several days to give brown crystals (3). The presence of Au and Ni atoms in 3 as transition-metal components was confirmed by X-ray fluorescence spectroscopy. The presence of d-pen and phen as organic components was indicated by the IR spectrum that showed characteristic ñC=O and ñC H bands at 1586 and 726 cm , respectively. 20] The electronic absorption spectrum of 3 exhibits a weak, broad band at around 920 nm assignable to the T2g !3 A2g transition for an octahedral Ni center and an intense, sharp band at around 250 nm assignable to the p–p* transition of phen (Figure 1). These data are compatible with the formation of the expected Au2Ni II 2 structure in [Au2Ni2ACHTUNGTRENNUNG(dpen)4 ACHTUNGTRENNUNG(phen)2]2 , which contains octahedral Ni centers with mixed d-pen and phen ligands. However, the elemental analytical data of 3 did not support this formula (d-pen/phen 2:1), but are instead consistent with a formula that contains d-pen and phen in a 1:1 ratio. This conflict was solved by single-crystal X-ray analysis that revealed the existence of [a] Dr. A. Igashira-Kamiyama, A. Fukushima, Prof. T. Konno Department of Chemistry, Graduate School of Science Osaka University, Toyonaka, Osaka 560-0043 (Japan) Fax: (+81) 6-6850-5765 E-mail : konno@chem.sci.osaka-u.ac.jp Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201303731.

Aggregation of chiral hexanuclear complex-cations into cationic metallosupramolecules with concomitant aggregation of inorganic counter-anions into anionic clusters

A chiral AuI4CoIII2 hexanuclear complex, [Au4Co2(dppe)2(D-pen)4]X2 (X = Cl−, ClO4−), was prepared from a digold(I) metalloligand, [Au2(dppe)(D-Hpen)2], in combination with CoIII. In the crystal, complex-cations and counter-anions of this complex were found to aggregate separately to form big cationic metallosupramolecular octahedrons and amazing adamantane-like anionic clusters, respectively.

Methanol-Triggered Turn-On-Type Photoluminescence in l-Cysteinato Palladium(II) and Platinum(II) Complexes Supported by a Bis(diphenylphosphine) Ligand

The selective detection of methanol by photoluminescence under environmental conditions has been a great challenge for materials science. Herein, a reversible, turn-on-type photoluminescence triggered by methanol vapor in square-planar palladium(II) and platinum(II) complexes, newly prepared from [MCl2(1,3-bis(diphenylphosphino)propane)] and L-cysteine, is reported. Both the turn-on and turn-off states of the complexes were crystallographically characterized, which revealed the presence of intermolecular OH···O and CH···π interactions between methanol and the complex molecules in the turn-on state. These interactions prevent the vibrational quenching of the luminescence, leading to the turn-on-type luminescence in this system.

Enantioselective/Anion-Selective Incorporation of Tris(ethylenediamine) Complexes into 2D Coordination Spaces between Tripalladium(II) Supramolecular Layers with d-Penicillaminate

The formation of a cocrystallized coordination compound, [Pd(3)(D-pen)(3)](2)·[M(en)(3)](ClO(4))(3) (D-H(2)pen = D-penicillamine; M = Co(III) or Rh(III)), from [Pd(3)(D-pen)(3)] and [M(en)(3)](ClO(4))(3) is reported. In this compound, only the Δ-configurational [M(en)(3)](3+) cations were incorporated when its racemic (Δ/Λ) isomer was employed. Besides this enantioselective incorporation of complex cations, this compound was found to show the selective incorporation of ClO(4)(-) as the anion species.

Synthesis and coordination behavior of a bipyridine platinum(II) complex with thioglucose.

A mononuclear platinum(II) complex with two monodentate-S H4tg(-) ligands, [Pt(H4tg-κS)2(bpy)] (1), was newly synthesized by the reaction of [PtCl2(bpy)] (bpy = 2,2-bipyridyl) with NaH4tg (NaH4tg =1-thio-β-d-glucose sodium salt) in water. Complex 1 reacted with additional [PtCl2(bpy)] in water to give an S-bridged dinuclear complex, [Pt2(μ2-H4tg-κ(1)S:κ(1)S)2(bpy)2](2+) ([2](2+)), in which a square-planar [Pt(H4tg)2(bpy)] unit binds to a [Pt(bpy)](2+) moiety through two thiolato groups. Treatments of 1 with Cu(2+) and Ni(2+) in water in the presence of bpy produced S-bridged dinuclear complexes [PtCu(μ2-H4tg-κ(1)S:κ(2)O,S)2(bpy)2](2+) ([3](2+)) and [PtNi(μ2-H4tg-κ(1)S:κ(2)O,S)2(bpy)2](2+) ([4](2+)), respectively, in which a square-planar [Pt(H4tg)2(bpy)] unit binds to a [M(bpy)](2+) (M = Cu(II), Ni(II)) moiety through two thiolato and two hydroxyl groups to form a chiral [M(N)2(O)2(S)2] octahedron with the Δ configuration. On the other hand, similar treatment with Cd(2+) in the presence of bpy resulted in the formation of an S-bridged trinuclear complex, [Cd{Pt(μ2-H4tg-κ(1)S:κ(2)O,S)(μ2-H4tg-κ(1)S:κ(1)S)(bpy)}2](2+) ([5](2+)), in which each of two square-planar [Pt(H4tg)2(bpy)] units binds to a Cd(II) ion through two thiolato groups and one hydroxyl group to form a chiral [Cd(O)2(S)4] octahedron with the Λ configuration. Of two geometrical configurations, syn and anti, which arise from the relative arrangement of two β-D-pyranose moieties, [2](2+) adopts the syn configuration with symmetric bridging sulfur atoms, while [3](2+), [4](2+), and [5](2+) all have the anti configuration with R configurational bridging sulfur atoms. All of the complexes were fully characterized by electronic absorption, CD, and NMR spectroscopies, along with single-crystal X-ray crystallography.

A 1 : 1 intercluster compound consisting of +6 and −6 charged RhIII4ZnII4 octanuclear cations and anions with aminothiolate ligands

The first example of a 1u2006:u20061 metal–organic intercluster compound with +6 charged cations and −6 charged anions was synthesized from [Zn4O{Rh(aet)3}4]6+ (aet = 2-aminoethanethiolate) and [Zn4O{Rh(L-cys)3}4]6− (L-cys = L-cysteinate). Its structure was determined by single-crystal X-ray crystallography, which revealed the formation of a diamondoid (dia) hydrogen-bonding network of the cluster anions, accommodating the cluster cations in its cavities.

Bis(bipyridine)ruthenium(II) complexes with an aliphatic sulfinato donor: synthesis, characterization, and properties.

Treatment of a thiolato-bridged Ru(II)Ag(I)Ru(II) trinuclear complex, [Ag{Ru(aet)(bpy)(2)}(2)](3+) (aet = 2-aminoethanthiolate; bpy = 2,2-bipyridine), with NaI in aqueous ethanol under an aerobic condition afforded a mononuclear ruthenium(II) complex having an S-bonded sulfinato group, [1](+) ([Ru(aesi-N, S)(bpy)(2)](+) (aesi = 2-aminoethanesulfinate)). Similar treatment of optically active isomers of an analogous Ru(II)Ag(I)Ru(II) trinuclear complex, Δ(D)Δ(D)- and Λ(D)Λ(D)-[Ag{Ru(d-Hpen-O,S)(bpy)(2)}(2)](3+) (d-pen = d-penicillaminate), with NaI also produced mononuclear ruthenium(II) isomers with an S-bonded sulfinato group, Δ(D)- and Λ(D)-[2](+) ([Ru(d-Hpsi-O,S)(bpy)(2)](+) (d-psi = d-penicillaminesulfinate)), respectively, retaining the bidentate-O,S coordination mode of a d-Hpen ligand and the absolute configuration (Δ or Λ) about a Ru(II) center. On refluxing in water, the Δ(D) isomer of [2](+) underwent a linkage isomerization to form Δ(D)-[3] (+) ([Ru(d-Hpsi-N,S)(bpy)(2)](+)), in which a d-Hpsi ligand coordinates to a Ru(II) center in a bidentate-N,S mode. Complexes [1](+), Δ(D)- and Λ(D)-[2](+), and Δ(D)-[3](+) were fully characterized by electronic absorption, CD, NMR, and IR spectroscopies, together with single-crystal X-ray crystallography. The electrochemical properties of these complexes, which are highly dependent on the coordination mode of sulfinate ligands, are also described.

Crystalline-Amorphous-Crystalline Transformation in a Highly Brilliant Luminescent System with Trigonal-Planar Gold(I) Centers

Photoluminescent compounds showing emission color changes in response to external stimuli have received considerable attention because of their wide range of applications. Here, we report the unique photoluminescence behavior of a digold(I) coordination system with trigonal-planar AuI centers, [Au2(dppm)3]2+ (dppmu2009=u2009bis(diphenylphosphino)methane). This system shows an extremely intense phosphorescence, with a quantum yield of >95% in the solid state. Both the emission color and thermal stability vary due to changing counter ions (Cl− vs. OTf−). Of particular note is the thermal crystalline-amorphous-crystalline transformation for the chloride salt, which is accompanied by drastic emission color changes. Single-crystal and powder X-ray diffractions demonstrate that the two-step transformation is induced by the loss of water molecules of crystallization with the subsequent removal of a dppm ligand to form [Au2(dppm)2]2+, which is mechanically reverted back to [Au2(dppm)3]2+.

The first crystal structure of an alkaline metal salt of thioglucose: potassium 1-thio-β-D-glucoside monohydrate.

In the crystal structure of the title hydrated salt, poly[(μ(2)-aqua)(μ(4)-1-sulfido-β-D-glucoside)potassium], [K(C(6)H(11)O(5)S)(H(2)O)](n) or K(+)·C(6)H(11)O(5)S(-)·H(2)O, each thioglucoside anion coordinates to four K(+) cations through three of its four hydroxy groups, forming a three-dimensional polymeric structure. The negatively charged thiolate group in each anion does not form an efficient coordination bond with a K(+) cation, but forms intermolecular hydrogen bonds with four hydroxy groups, which appears to sustain the polymeric structure. The Cremer-Pople parameters for the thioglucoside ligand (Q = 0.575, θ = 8.233° and ϕ = 353.773°) indicate a slight distortion of the pyranose ring.