Synthesis and Photophysical Properties of T-Shaped Coinage-Metal Complexes

The photophysical properties of a series of T-shaped coinage d¹⁰ metal complexes, supported by a bis(mesoionic carbene)carbazolide (CNC) pincer ligand, are explored. The series includes a rare new example of a tridentate T-shaped Ag^I complex. Post-complexation modification of the Au^I complex provides access to a linear cationic Au^I complex following ligand alkylation, or the first example of a cationic square planar Au^III−F complex from electrophilic attack on the metal centre. Emissions ranging from blue (Cu^I) to orange (Ag^I) are obtained, with variable contributions of thermally-dependent fluorescence and phosphorescence to the observed photoluminescence. Green emissions are observed for all three gold complexes (neutral T-shaped Au^I, cationic linear Au^I and square planar cationic Au^III). The higher quantum yield and longer decay lifetime of the linear gold(I) complex are indicative of increased phosphorescence contribution.     

A Bis(Diphosphanyl N‐Heterocyclic Carbene) Gold Complex: A Synthon for Luminescent Rigid AuAg2 Arrays and Au5 and Cu6 Double Arrays

A mononuclear bis(NHC)/Au^I (NHC=N‐heterocyclic carbene) cationic complex with a rigid bis(phosphane)‐functionalized NHC ligand (PC_NHCP) was used to construct linear Au₃ and Ag₂Au arrays, a Au₅ cluster with two intersecting crosslike Au₃ arrays, and an unprecedented Cu₆ complex with two parallel Cu₃ arrays. The impact of metallophilic interactions on photoluminescence was studied experimentally.     

Cyclic voltammetric and e.s.r. studies of a tetraaza 14-membered macrocyclic copper(II) complex derived from 3-salicylideneacetylacetone ando-phenylenediamine: stabilization and activation of unusual oxidation states

Summary A 14-membered macrocyclic Schiff base derived from 3-salicylideneacetylacetone ando-phenylenediamine acts as a tetradentate and strongly conjugated ligand to form a cationic solid complex with CuCl₂. U.v.-vis. and e.s.r. spectral data reveal a strong ligand to metal -interaction in the square planar complex. C.v. data reveal that the title ligand is able to stabilize the copper(III) oxidation state more effectively than comparable saturated or partially unsaturated macrocyclic ligands and confers a weaker tendency for reduction of copper(II) to copper(I) and copper(0). While the inclusion of a PPh₃ ligand suppresses the Cu⁰ Cu^I Cu^II oxidation, imidazole and pyridine strongly enhance the Cu^II Cu^III oxidation of the complex.     

Three 3D hybrid networks based on octamolybdates and different Cu/Cu-bis(triazole) motifs

Three 3D compounds based on octamolybdate clusters and various Cu^I/Cu^II-bis(triazole) motifs, [Cu^I₂btb][β-Mo₈O₂₆]_0.5 (1), [Cu^I₂btpe][β-Mo₈O₂₆]_0.5 (2), and [Cu^II(btpe)₂][β-Mo₈O₂₆]_0.5 (3) [btb=1,4-bis(1,2,4-triazol-1-yl)butane, btpe=1,5-bis(1,2,4-triazol-1-yl)pentane], were isolated via tuning flexible ligand spacer length and metal coordination preferences. In 1, the copper(I)-btb motif is a one-dimensional (1D) chain which is further linked by hexadentate β-[Mo₈O₂₆]⁴⁻ clusters via coordinating to Cu^I cations giving a 3D structure. In 2, the copper(I)-btpe motif exhibits a “stairs”-like [Cu^I₂btpe]²⁺ sheet, and the tetradentate β-[Mo₈O₂₆]⁴⁻ clusters interact with two neighboring [Cu^I₂btpe]²⁺ sheets constructing a 3D framework. In 3, the copper(II)-btpe motif possesses a novel (2D→3D) interdigitated structure, which is further connected by the tetradentate β-[Mo₈O₂₆]⁴⁻ clusters forming a 3D framework. The thermal stability and luminescent properties of 1-3 are investigated in the solid state.     

New heterometallic coordination polymers derived form chalcogenocyanates: synthesis,characterization and electrical properties

A series of conducting mixed-metallic coordination polymers: Cu₂Pb(SCN)₄, CuPb(SeCN)₄, Cu^II _0.50Cu^IPb (SCN·SeCN)₂, CuAg(SCN)₂, CuAg(SeCN)₂ and CuAg(SCN·SeCN) have been synthesized by the reaction of Cu and Pb^II or Ag^Initrates with KSCN or KSeCN, or both KSCN and KSeCN in H₂O. Of significance are the aerobic reactions which yield heterometallic complexes viaoxidation of SCN^– and SeCN^– into (SCN)₂ and (SeCN)₂ followed by quantitative reduction of Cu^II into Cu^I; in the case of CuPb(SeCN)₄ reduction of Cu^II into Cu^I is not observed, while in Cu^{II 0.50}Cu^IPb(SCN·SeCN)₂, Cu^II is partially reduced to Cu^I. These compounds have been characterized by elemental (C, N, S and Se) analyses, magnetic moment measurements, relevant spectroscopies (i.r., far i.r., Raman, u.v.–vis. and e.p.r.), powder X-ray diffraction pattern and conductivity technique. The v(CN) vibrations in 2162–2087cm^–1 and far i.r. bands (500–100cm^–1) corroborated by Raman bands are conclusive of the bridging (N, S/Se) mode and metal-NCS and metal-SCN/SeCN^– bonding respectively in the complexes. Room temperature magnetic moment, electronic absorption spectra and e.p.r. active/silent nature confirm the oxidation state of copper in these solids. Room temperature compressed pellet conductivities _rt, 10^–9to 10^–7Scm^–1 with activation energies, E _a=0.19–0.25eV and increase in the conductivity with increase in temperature in the 305–423K, range and decrease in conductivity with decrease in temperature in the 295–200K range, show their semiconductor properties.     

A Tray‐Shaped,PdII‐Clipped Au3 Complex as a Scaffold for the Modular Assembly of [3×n] Au Ion Clusters

A tray‐shaped Pd^II₃Au^I₃ complex ( 1 ) is prepared from 3,5‐bis(3‐pyridyl)pyrazole by means of tricyclization with Au^I followed by Pd^II clipping. Tray 1 is an efficient scaffold for the modular assembly of [3×n] Au^I clusters. Treatment of 1 with the Au^I₃ tricyclic guest 2 in H₂O/CH₃CN (7:3) or H₂O results in the selective formation of a [3×2] cluster ( 1 ? 2 ) or a [3×3] cluster ( 1 ? 2 ? 1 ), respectively. Upon subsequent addition of Ag^I ions, these complexes are converted to an unprecedented Au₃–Au₃–Ag–Au₃–Au₃ metal ion cluster.     

A Tray‐Shaped,PdII‐Clipped Au3 Complex as a Scaffold for the Modular Assembly of [3×n] Au Ion Clusters

A tray‐shaped Pd^II₃Au^I₃ complex ( 1 ) is prepared from 3,5‐bis(3‐pyridyl)pyrazole by means of tricyclization with Au^I followed by Pd^II clipping. Tray 1 is an efficient scaffold for the modular assembly of [3×n] Au^I clusters. Treatment of 1 with the Au^I₃ tricyclic guest 2 in H₂O/CH₃CN (7:3) or H₂O results in the selective formation of a [3×2] cluster ( 1 ⋅ 2 ) or a [3×3] cluster ( 1 ⋅ 2 ⋅ 1 ), respectively. Upon subsequent addition of Ag^I ions, these complexes are converted to an unprecedented Au₃–Au₃–Ag–Au₃–Au₃ metal ion cluster.     

Solid-state electrode with a Cu(I)-based membrane hydrophobised by PTFE for the measurement of Cu2+ and I?

The preparation of CuI + Ag₂S and Cu₂[HgI₄] + Ag₂S membranes hydrophobised by PTFE is described. The pressed membranes mounted in a multi-purpose all-solid-state electrode body have been examined as electrochemical sensors for Cu²⁺ and I^– ions. For the electrode with (CuI + Ag₂S + PTFE)-membrane experimental slopes of 29 mV(pCu)^–1 and 62 mV(pI)^–1 were obtained, in good agreement with the theoretical values. For practical measurement in solutions where both Cu²⁺ and I^– can be present, the investigated electrode offers certain advantages in comparison with a commercial Cu-ISE.     

A 116-Nuclear Metallosupramolecular Cage-of-Cage Showing Multistep Single-Crystal-to-Single-Crystal Transformation

Here a unique single-crystal-to-single-crystal (SCSC) transformation of a 116-nuclear Au^I₇₂Cd^II₄₀Na^I₄ cage-of-cage ( 2 _CdNa) is reported, which was created from a trigold(I) metalloligand with d -penicillamine by way of a 9-nuclear Au^I₆Cd^II₃ cage ( 1 ). Cage-of-cage 2 _CdNa is composed of 12 cages of 1 that are linked by 4 Cd²⁺ and 4 Na⁺ ions, with its surface being covered by 12 NO₃⁻ ions to form a discrete, spherical molecule with a diameter ca. 4.7 nm. In crystal 2 _CdNa, the cage-of-cage molecules are packed in a cubic lattice with a huge cell volume of ca. 4.5×10⁵ ų_, so as to have large interstices with diameters of more than 3 nm. Upon soaking crystals 2 _CdNa in aqueous Cu(NO₃)₂, all Cd²⁺ and Na⁺ were quickly exchanged by Cu²⁺ to produce an analogous Au^I₇₂Cu^II₄₄ cage-of-cage ( 2 _Cu) in a SCSC manner. Prolonged soaking led to the SCSC transformation to another supramolecular structure ( 2′ _Cu) consisting of 152-nuclear Au^I₇₂Cu^II₈₀ cage-of-cages that are alternately H-bonded with the Au^I₇₂Cu^II₄₄ cage-of-cages. 2′ _Cu showed the accommodation of MoO₄²⁻ and the conversion of MoO₄²⁻ to β-Mo₈O₂₆⁴⁻ in the crystal, with retention of single-crystallinity.     

Arsolyl-supported intermetallic dative bonding

The first examples of late transition metal η⁵-arsolyls (L = CO, P(OMe)₃; R = Ph, Me, Et, SiMe₃; R′ = Ph, H, Me, Et, Me) serve as ditopic donors to extraneous metal centres (M = Pt^II, Au^I, Hg^II) through both conventional As → M and polar-covalent (dative) Co → M interactions.

Cobalt carbonyl reacts with arsoles to provide the first late transition metal η⁵-arsolyls. These serve as ditopic donors to extraneous metal centres (M = Pt^II, Au^I, Hg^II) through both conventional AsM and polar-covalent (dative) CoM interactions.     

Encapsulation of tricopper cluster in a synthetic cryptand enables facile redox processes from CuICuICuI to CuIICuIICuII states

One-pot reaction of tris(2-aminoethyl)amine (TREN), [Cu^I(MeCN)₄]PF₆, and paraformaldehyde affords a mixed-valent [TREN₄Cu^IICu^ICu^I(μ₃-OH)](PF₆)₃ complex. The macrocyclic azacryptand TREN₄ contains four TREN motifs, three of which provide a bowl-shape binding pocket for the [Cu₃(μ₃-OH)]³⁺ core. The fourth TREN caps on top of the tricopper cluster to form a cryptand, imposing conformational constraints and preventing solvent interaction. Contrasting the limited redox capability of synthetic tricopper complexes reported so far, [TREN₄Cu^IICu^ICu^I(μ₃-OH)](PF₆)₃ exhibits several reversible single-electron redox events. The distinct electrochemical behaviors of [TREN₄Cu^IICu^ICu^I(μ₃-OH)](PF₆)₃ and its solvent-exposed analog [TREN₃Cu^IICu^IICu^II(μ₃-O)](PF₆)₄ suggest that isolation of tricopper core in a cryptand enables facile electron transfer, allowing potential application of synthetic tricopper complexes as redox catalysts. Indeed, the fully reduced [TREN₄Cu^ICu^ICu^I(μ₃-OH)](PF₆)₂ can reduce O₂ under acidic conditions. The geometric constraints provided by the cryptand are reminiscent of Nature''s multicopper oxidases (MCOs). For the first time, a synthetic tricopper cluster was isolated and fully characterized at Cu^ICu^ICu^I (4a), Cu^IICu^ICu^I (4b), and Cu^IICu^IICu^I (4c) states, providing structural and spectroscopic models for many intermediates in MCOs. Fast electron transfer rates (10⁵ to 10⁶ M⁻¹ s⁻¹) were observed for both Cu^ICu^ICu^I/Cu^IICu^ICu^I and Cu^IICu^ICu^I/Cu^IICu^IICu^I redox couples, approaching the rapid electron transfer rates of copper sites in MCO.

Geometric constraints and site isolation provided by the cryptand enable reversible redox of tricopper μ-oxo cluster.     

Synthesis,spectroscopic characterization,and crystal structures of copper(I) iodide clusters of N-methylthiourea and 1,3-diazinane-2-thione

Two copper(I) iodide complexes, [Cu₄(Metu)₆I₄] (I) and [Cu₈(Diaz)₁₂I₈] (II) (Metu = N-methylthiourea; Diaz = 1,3-diazinane-2-thione), have been prepared and their structures been determined by X-ray crystallography. The crystal structures show that complex I is a tetranuclear, while II is an octanuclear cluster, both having a Cu : S ratio of 2 : 3, characteristic of metallothioneins. In I, each of the four copper atoms is coordinated to three thiourea ligands and one iodide ion in a distorted tetrahedral mode adopting admantane-like structure. In II, four types of core arrangements are observed around copper(I), which include, Cu(μ-S₂)I₂, Cu(μ-S₂)(μ-I)I, Cu(μ-S₃)I, and Cu(μ-S₃)S each having copper(I) tetrahedrally coordinated. The complexes were also characterized by IR and ¹H and ¹³C NMR spectroscopy.     

Synthesis and Crystal Structure of the Heterovalent Copper(I,II) π-Complex Cu7Br6.48Cl1.52 ? 2C3N3(OC3H5)3

Single crystals of the heterovalent Cu^I,Cu^II π,σ-complex Cu₇Br_6.48Cl_1.52 ⋅ 2C₃N₃(OC₃H₅)₃ are synthesized by the ac electrochemical method from an ethanol solution containing 2,4,6-triallyloxy-1,3,5-triazine, CuCl₂ ⋅ 2H₂O, and CuBr₂. The unit cell parameters of the crystals are: space group , a = 8.271(3) Å, b = 11.391(3) Å, c = 11.821(3) Å, α = 67.43(1)°, β = 84.41(2)°, γ = 85.14(2)°, V = 1022(1) ų, and R(F) = 0.0714. The copper and halogen atoms form unique moieties Cu₆X₆ linked by bridging fragments [Cu²⁺ (C₃N₃(OC₃H₅)₃)₂]X₂ into infinite chains. Each inorganic moiety Cu₆X₆ is linked with four 2,4,6-triallyl- oxy-1,3,5-triazine molecules. The ligand molecule is coordinated to one Cu^II atom through the nitrogen atom of the triazine cycle and to two Cu^I atoms through the C=C bonds of two allyl groups. The Br content equal to 0.57 in the X(4) position linking the Cu^I and Cu^II atoms differs markedly from a value of 0.85–0.91 for the X(1), X(2), and X(3) positions linked only with the Cu(I) atoms.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 6, 2005, pp. 455–461.Original Russian Text Copyright © 2005 by Goreshnik, Schollmeyer, Mys’kiv.     

Coordination modes of 1-allyl benzotriazole: synthesis and characterization of cobalt(II), nickel(II), copper(II), copper(I) and silver(I) complexes

Summary The synthesis and coordination behaviour of 1-allylbenzotriazole (ABT), containing both -donating heterocyclic ring nitrogen(s) and a -bonding olefinic group, has been studied by complexation with Co^II, Ni^II, Cu^II, Cu^I and Ag^I salts. The solid complexes M(ABT)₂X₂ (M=Co, Ni or Cu and X=a counterion) and M(ABT)X (M=Cu or Ag and X=Br, I, or NO₃) have been characterised by¹H-n.m.r. (representative Cu^I species) and other physical data. Different modes coordination for the title ligand have been proposed based upon i.r. data which indicate the participation of a -donating ring nitrogen only in complexes with bivalent metal salts, and the involvement of both the ring nitrogen and the allylic olefinic component in bonding to a monovalent metal ion.¹H-n.m.r. data are qualitatively commensurate with participation of the allyl group in monovalent metal complexes.     

Synthesis and characterization of Ru/Au,Pd/Au,Pd/2Au,Pt/2Au and Cu/2Au heterometallic complexes of cyclodiphosphazane cis-{(o-MeOC6H4O)P(μ-NBu)}2

Mononuclear complexes of cyclodiphosphazane with an uncoordinated phosphorus centre [RuCl₂(η⁶-cymene){l-κP}] (1a) (L = cis-{(o-MeOC₆H₄O)P(μ-N^tBu)}₂) and [PdCl₂(PEt₃){l-κP}] (1b) react with 1 equiv. of [AuCl(SMe₂)] to afford Ru^II/Au^I and Pd^II/Au^I heterodinuclear complexes [RuCl₂(η⁶-cymene){μ-l-κP,κP}AuCl] (2) and [PdCl₂(PEt₃){μ-l-κP,κP}AuCl] (3), respectively. Heterotrinuclear complexes [PdCl₂{μ-l-κP,κP}₂(AuCl)₂] (4), [PtCl₂{μ-l-κP,κP}₂(AuCl)₂] (5) and [CuI{μ-l-κP,κP}₂(AuCl)₂] (6) containing Pd^II/2Au^I, Pt^II/2Au^I and Cu^I/2Au^I metal centers have been synthesized from the reactions of trans-[PdCl₂{l-κP}₂] (1c), cis-[PtCl₂{l-κP}₂] (1d) and [CuI{{l-κP}₂] (1f) respectively, with 2 equiv. of [AuCl(SMe₂)]. Molecular structures of complexes 2, 3 and 4 were established by single crystal X-ray diffraction studies.     

Mixed metal complexes in solution. Thermodynamic and spectrophotometric study of copper(II)-citrate heterobinuclear complexes with nickel(II), zinc(II) or cadmium(II) in aqueous solution

Summary A thermodynamic study of Cu^II–M^II-citrate (M^II=Ni^II, Zn^II or Cd^II) ternary systems has been performed by means of potentiometric measurements of hydrogen ion concentration at different temperatures (10, 25, 35 and 45°C) and at I=0.1 mol dm^–3 (KNO₃).The different binary and ternary systems involved have been further characterized by visible spectra and by calculating the spectra ( versus ) of all the Cu^II complexes.The thermodynamic data suggest strong entropic stabilization for the species under discussion. As regards the visible spectral characteristics of Cu^II(d-d transitions), the substitution of one Cu^II ion in the dimer [Cu₂(cit)₂H_–2]^4– by Ni^II or Zn^II to form heterobinuclear [CuM(cit)₂H_–2]^4– complexes, gives rise to a change in the visible spectrum.     

Simulation of donor-acceptor electron-transport systems in the example case of the oxidation of copper in media of organic solvents

The interaction of the onium salts [Me₂ Et=O]BF₄ ^–, [Me₂ =CH-OEt]BF₄ ^–, and [Me₃ =O]I^– with metallic copper in DMSO, DMF, and acetonitrile (AN) has been investigated. It has been shown that the reaction takes place with an intermediate step involving the formation of Cu(I) compounds. The complexes [Cu^I(AN)₄]BF₄, [Cu^II(DMSO)₅](BF₄)₂, [Cu^II(DMSO)₄(AN)₂](BF₄)₂, [Cu^II(DMSO)₂(DMF)(AN)](BF₄)₂, and [ME₃ ]₃Cu^II₄ · [Me₃ =O]I^– have been isolated and characterized. It has been established that dipolar onium compounds which simulate the intermediate products of the interaction of the components of donor-acceptor electron-transport systems are responsible for the oxidation of metals in organic complex-forming media.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1325–1330, June, 1991.     

Synthesis,spectroscopy and electrochemistry of mono and dinuclear complexes of a peripherally mixed ligand and the interaction of (E,E) Ni(LH)2 with Pd2+ and Ag+

We describe the synthesis, characterization and electrochemistry of a new family of peripherally functionalised vic-dioxime, 5,6-bis-(hydroxyimino)-1,2,9,10-hydroxy-4,7-dithiadecane (LH₂), with bis-(thiopropandiol) moieties attached to the oxime. Thiopolyalcohol groups containing two different heteroatoms (—S— and —O—) serve as weak exocyclic binding sites for Pd⁺² and Ag⁺ ions. Novel mononuclear (LH)₂M, (M = Ni^II, Cu^II, Co^II, Mn^II and Fe^II), homodinuclear (LH)₂(UO₂)₂(OH) and heterotrinuclear (LH)₂MM₂ (M = Ni^II and M = Pd^II and Ag^I) species have been obtained with the metal:ligand ratios of 1:2, 2:2, and 3:2 respectively. Metal ions coordinate through N,N of the oxime and S,O donor sites of the peripherally attached groups in the presence of the base. The heterotrinuclear complexes were prepared by the interaction of the mononuclear complex, (LH)₂Ni, with Pd(C₅H₅)₂ and AgNO₃ in an appropriate solvent. The complexes were characterized by elemental analysis, ¹H-n.m.r., u.v.–vis. spectroscopy, FT-IR., and by f.a.b-m.s. The redox properties of the complexes were studied by cyclic voltammetry.     

Synthesis,spectroscopy and thermal properties of the nickel(II), palladium(II) and copper(II) complexes of bis(aminoalkyl)-oxamides (=LH2) including the crystal structure of Cu2L(NO3)2

Summary The synthesis of the Ni^II, Pd^II and Cu^II complexes of N, N-bis(aminoalkyl)oxamides (LH₂) is described and structures are proposed on the basis of their physical and spectroscopic properties. With Ni^II and Pd^II only one complex is formed with general formula NiL or PdL, characterised by coordination through two deprotonated amide N-atoms and two terminal NH₂ groups. With Cu^II it proved possible to obtain three structurally different compounds, depending on the pH, with general formulae Cu(LH₂)X₂, Cu₂(L)X₂ and CuL in which X=Cl, Br or NO₃. The structure of [Cu₂(C₈O₂N₄H₁₆](NO₃)₂ was solved by means ofx-ray diffraction; Mr=451.33, monoclinic, space group P2₁/n, a=9.503(4), b=7.614(1), c=10.407(3) Å, =98.43(3)°, V=744.3(7)ų, Z=2, Dx=1.202 g cm^–3, =1.33 cm^–1, (MoK)=0.71073 Å, F(000)=520, room temperature, R=0.043, wR=0.047 for 1080 observed [I>-3(I)] not systematically absent reflections out of 1423 measurements and 137 variables. The compound has a conformational chair/boat disorder with 82% in the more stable chair form.