Structural organization and thermal behavior of the heteropolynuclear complex [Au2{S2CN(CH3)2}4][ZnCl4] and the heterovalent complex ([Au{S2CN(CH3)2}2][AuCl2]) n obtained in the chemisorption system [Zn2{S2CN(CH3)2}4]-Au3+/2 M HCl

Reactions of freshly precipitated binuclear zinc dimethyldithiocarbamate with [AuCl₄]^? anions in 2 M HCl were studied. The heteropolynuclear complex [Au₂{S₂CN(CH₃)₂}₄][ZnCl₄] (I) and the polymeric heterovalent complex ([Au{S₂CN(CH₃)₂}₂][AuCl₂]) _n (II) were preparatively isolated from the chemisorption system [Zn₂{S₂CN(CH₃)₂}₄]-Au³⁺/2 M HCl. The products were characterized by ¹³C MAS NMR data and by X-ray diffraction determination of crystal and molecular structures. The principal structural units of compounds I and II are the tetragonal planar complex cations [Au{S₂CN(CH₃)₂}₂]⁺ (in which the complex-forming ion coordinates two MDtc ligands in the S,S′-bidentate mode) and the anions, namely, the distorted tetrahedral anion [ZnCl₄]^2? in I and the linear [AuCl₂]^? anion in II. The further structural self-organization of complexes at the supramoleular level occurs through relatively weak secondary bonds Au?S and Au?Cl. The chemisorption capacities of zinc dimethyldithiocarbamate calculated from gold(III)-binding reactions are 644.1 and 1288.2 mg of gold per gram of the sorbent. Simultaneous thermal analysis studies of the thermal behavior of I and II were used to elucidate the conditions of gold recovery.     

Binding forms of gold(III) from solutions by cadmium diethyl dithiocarbamate: Thermal behavior and role of secondary interactions in the supramolecular self-assembly of polymeric complexes ([Au{S2CN(C2H5)2}2][AuCl4]) n and [Au{S2CN(C2H5)2}Cl2] n

The chemisorption interaction between the binuclear cadmium diethyl dithiocarbamate (EDtc), [Cd₂{S₂CN(C₂H₅)₂}₄], (chemisorbent I) and AuCl₃ solutions in 2 M HCl results in the formation of polymeric gold(III) complexes: ([Au{S₂CN(C₂H₅)₂}₂][AuCl₄]) _n (II) and [Au{S₂CN(C₂H₅)₂}Cl₂] _n (III) with the same Au : EDtc : Cl ratio (1 : 1 : 2). The alternating centrosymmetric cations and anions of complex II are structurally self-assembled to form linear polymeric chains: the gold atom in [Au{S₂CN(C₂H₅)₂}₂]⁺ forms secondary Au(1)?Cl(1) bonds (3.7784 Å) with two neighboring [AuCl₄]^? anions. This binding is additionally strengthened by secondary S(1)?Cl(1) interactions (3.4993 Å). The mixed-ligand complex III comprises two structurally non-equivalent molecules [Au{S₂CN(C₂H₅)₂}Cl₂]: A—Au(1) and B—Au(2), each being in contact with two nearest neighbors through pairs of unsymmetrical secondary bonds: Au(1)?S(1)^a/b 3.4361/3.6329; and Au(2)?S(4)^c/d 3.4340/3.6398 Å. At the supramolecular level, this gives rise to independent zigzag-like polymeric chains, (?A?A?A?) _n and (?B?B?B?) _n along which antiparallel isomeric molecules of III alternate. The chemisorption capacity of cadmium diethyl dithiocarbamate calculated from the gold(III) binding reaction is 963.2 mg of gold per 1 g of the sorbent. The recovery conditions for the bound gold were elucidated by simultaneous thermal analysis of II and III. The DSC curves reflect different sets of heat effects, because thermolysis occurs for complex molecules (III) or for cations and anions (II). Nevertheless, the patterns of experimental TG curves are similar despite different structures of the complexes. The final product of thermal transformations is reduced gold.     

Chemisorption of the [AuCl4]− anion by cadmium cyclo-pentamethylenedithiocarbamate and the resulting bound-gold(III) species: The supramolecular structure and thermal behavior of the polynuclear complexes ([Au{S2CN(CH2)5}2]2[CdCl4]) n and ([Au{S2CN(CH2)5}Cl2]) n

The interaction between cadmium cyclo-pentamethylenedithiocarbamate (chemisorbent Ia) and the [AuCl₄]^? anion in 2 M HCl has been investigated. The state of the chemisorbent in contact with AuCl₃ solutions has been probed by ¹¹³Cd MAS NMR spectroscopy. The heterogeneous reactions in the system, including gold(III) chemisorption from the solution and partial ion exchange, yield the gold(III)-cadmium heteropolynuclear complex ([Au{S₂CN(CH₂)₅}₂]₂[CdCl₄]) _n (I) and the polynuclear mixed-ligand complex ([Au{S₂CN(CH₂)₅}Cl₂]) _n (II). The crystal and molecular structures of these compounds have been determined by X-ray crystallography. The main structural units of the compounds are the complex cation [Au{S₂CN(CH₂)₅}₂]⁺, [CdCl₄]^2? anion (in I), and Au{S₂CN(CH₂)₅}Cl₂ molecule (in II). The further structural self-organization of the complexes at the supramolecular level is due to secondary Au...S and Au...Au bonds. [Au₂{S₂CN(CH₂)₅}₄]²⁺ dinuclear cations form in the structure of I, which then polymerize into ([Au₂{S₂CN(CH₂)₅}₄]²⁺) _n chains. In the structure of II, adjacent Au{S₂CN(CH₂)₅}Cl₂ molecules join by forming pairs of asymmetric secondary Au...S bonds, producing polymer chains with alternating antiparallel monomer units. The chemisorption capacity values calculated for cadmium cyclo-pentamethylenedithiocarbamate from gold(III) binding reactions are 455 and 910 mg of gold per gram of sorbent. The gold recovery conditions have been determined by investigating the thermal behavior of I and II by synchronous thermal analysis. The multistep thermal destruction of ionic complex I includes the thermolysis of its carbamate moiety and [CdCl₄]_2? (which liberates gold metal and cadmium chloride and yield some amount of CdS) and CdCl₂ and CdS evaporation. The thermolysis of II proceeds via the formation of Au₂S and AuCl as intermediate compounds. In both cases, the ultimate pyrolysis product is elemental gold.     

Xanthate complexes of {Nb2S4}4+

Alkyl xanthate complexes [Nb₂S₄(S₂COR)₄] (R = Et (I), iso-Pr (II), n-Bu (III), and iso-Am (IV)) are synthesized by the ligand exchange reaction in solutions from (Et₄N)₄[Nb₂S₄(NCS)₈] and the corresponding potassium salts in satisfactory yields. The X-ray diffraction analyses are carried out for the isopropyl xanthate (II) and butyl xanthate (III) complexes. From the view point of mutual arrangement of chelate cycles, complexes II and III exist in crystals as ΛΔ isomers. The niobium-niobium distances are 2.8789(4) Å in complex II and 2.8856(3) Å in complex III. The first example for the formation of short S...S contacts between the disulfide ligands of the {Nb₂S₄}⁴⁺ fragments in the crystal structure of III is found (3.146 Å).     

Synthesis and structure of cluster compounds containing a novel cluster core {Re4STe3}

Three novel cluster compounds K₄[Re₄STe₃(CN)₁₂]·₄H₂O (I), [{Cu(en)₂}₂Re₄STe₃(CN)₁₂]·₅H₂O (II) and [{Cu(trien)}₂Re₄STe₃(CN)₁₂]·2H₂O (III) (en is ethylenediamine, trien is triethylenetetraamine) containing a new cluster core {Re₄STe₃} have been prepared and structurally characterized. According to single crystal X-ray diffraction data, compound I is ionic and represents the arrangement of ions K⁺ and [Re₄STe₃(CN)₁₂]^4?; compounds II and III are molecular and formed by two cationic moieties {Cu(en)₂}²⁺ and {Cu(trien)}²⁺, respectively, coordinated to one cluster anion. In the solid state, S atom positions in the tetrahedron Q₄ (Q = S, Te) are disordered for all three compounds: in I and III sulfur atoms are split over all four Q positions, while in II over two positions.     

Formation of supramolecular complexes in reactions of adduct formation of zinc diethyldithiocarbamate with morpholine. Molecular structures and thermal properties

A supramolecular compound of the general formula [Zn{NH(CH₂)₄O} {S₂CN(C₂H₅)₂}₂]₄ · NH(CH₂)₄O · C₂H₄{N(CH₂)₄O}₂ (I) was obtained and examined by X-ray diffraction analysis and thermography. According to X-ray diffraction data, the crystal lattice of compound I shows an unusual alternation of two independent centrosymmetric supramolecular complexes [Zn{NH(CH₂)₄O} {S₂CN(C₂H₅)₂}₂]₂ · C₂H₄{N(CH₂)₄O}₂ (Ia) and [Zn{NH(CH₂)₄O} {S₂CN(C₂H₅)₂}₂]₂ · NH(CH₂)₄O (Ib). Either complex includes two molecules of an adduct of bis(diethyldithiocarbamato)zinc with morpholine and outer-sphere molecules of 1,2-dimorpholinoethane or morpholine. Adduct molecules are structurally nonequivalent in pairs and linked with solvate molecules by hydrogen bonds. The calculated geometries of the zinc polyhedra are intermediate between trigonal bipyramid and tetragonal pyramid. Thermal decomposition of supramolecular compound I proceeds through desorption of the outer-sphere and coordinated organic molecules; in the final step, defragmentation of the dithiocarbamate part gives zinc sulfide.     

Platinum(II) cyclo-hexamethylenedithiocarbamate complex, [Pt{S2CN(CH2)6}2] and its solvated form, [Pt{S2CN(CH2)6}2] · CHCl3: Crystal and molecular structures, 13C CP/MAS NMR data, and thermal behavior

Platinum(II) cyclo-hexamethylenedithiocarbamate (HmDtc) complex, [Pt{S₂CN(CH₂)₆}₂] (I), and its solvated form, Pt{S₂CN(CH₂)₆}₂] · CHCl₃ (II), are synthesized and characterized by the ¹³C MAS NMR data. The HmDtc ligands in structure I are not equivalent, whereas the solvation of the complex is accompanied by the structural unification of the initially nonequivalent HmDtc ligands. In addition, the spectra are characterized by the ¹³C-¹⁹⁵Pt spin-spin coupling. The noncentrosymmetric molecular structure of compound I determined by X-ray diffraction analysis includes two nonequivalent dithiocarbamate ligands coordinated by the metal in the S,S′-bidentate mode. The central atom forming the [PtS₄] chromophore (intraorbital dsp ²-hybrid state of platinum) shifts from the plane of four sulfur atoms by 0.07 Å in the vertex of the flattened tetragonal pyramid. The seven-membered heterocycles ?N(CH₂)₆ of the HmDtc ligands are oppositely directed in space relative to the [S₄] plane (trans orientation). The thermal behavior of compounds I and II are studied by simultaneous thermal analysis. In both cases, the final product of the multistage thermal destruction of the complexes is reduced metallic platinum.     

A fixation mode of gold(III) in the course of the chemisorption interaction with cadmium cyclo-hexamethylene dithiocarbamate: Structural organization and thermal behavior of the heteropolynuclear complex ([Au{S2CN(CH2)6}2]2[CdCl4] · 3/4H2O) n (an example of the complicated supramolecular structure)

The chemisorption interaction of binuclear cadmium cyclo-hexamethylene dithiocarbamate with H[AuCl₄] in a solution of 2 M HCl is studied. The state of the chemisorbent is monitored by ¹¹³Cd and ¹³C MAS NMR spectroscopy. The result of the heterogeneous reaction, including the chemisorption of gold(III) from a solution and partial ion exchange, is the formation of the heteropolynuclear gold(III)-cadmium complex. The crystal, molecular, and supramolecular structures of the hydrated form of the synthesized coordination compound ([Au{S₂CN(CH₂)₆}₂]₂[CdCl₄] · 3/4H₂O) _n (I) are determined by X-ray diffraction analysis. Compound I includes three structurally nonequivalent complex cations [Au{S₂CN(CH₂)₆}₂]⁺. The character of structural differences between them indicate that they correlate as conformers: cations (A), (B), and (C) are present in the ratio 2: 1: 1. The isomeric cations perform different functions in the self-organization of the chemical system into unusually complicated supramolecular structure I. Cations (A) form centrosymmetric dimers [Au₂{S₂CN(CH₂)₆}]²⁺, which are involved together with cations (B) in the formation of polymeric chains ([Au₂{S₂CN(CH₂)₆}]²⁺ · [Au{S₂CN(CH₂)₆}₂]⁺) _n alternating along the chain length. Cations (C) are structurally isolated, as well as anions [CdCl₄]^2?. The chemisorption capacity of the cadmium cyclo-hexamethylene dithiocarbamate complex calculated from the reaction of Au(III) binding is 427.2 mg of gold per 1 g of the sorbent. To establish the optimum conditions for the regeneration of bound gold, the thermal behavior of I is studied by simultaneous thermal analysis (STA). The multistage process of chemical destruction includes the desorption of hydrate water, the thermolysis of the dithiocarbamate part of the complex and [CdCl₄]^2? (with the release of metallic gold and cadmium chloride and the partial formation of CdS), and the evaporation of CdCl₂ and CdS. The final product of thermal transformations is reduced metallic gold.     

Complexes of Cu(II) and Co(II) nitrates with 3-Phenyl-5,5-dimethyl-5,6-dihydro-1,2,4-triazolo[3,4-a]isoquinoline

Complexes of Cu(II) and Co(II) nitrates with 3-phenyl-5,5-dimethyl-5,6-dihydro-1,2,4-triazolo[3,4-a]isoquinoline (L⁰) of the composition [CuL ₂ ⁰ (NO₃)₂] (I) and [CoL ₂ ⁰ (NO₃)₂] · CH₃CN (II) are synthesized and their crystal structures are determined by X-ray diffraction. The L⁰ ligand is coordinated to the metal atoms through the N atom in position 2 of triazole fragment. The coordination polyhedron of the Cu(II) atom is a square with two additional axial vertices, while that of the Co(II) atom is a tetrahedron with two additional vertices. The NO ₃ ^? groups in the structures of I and II perform similar anisobidentate function. Complexes I and II are studied by IR and electronic spectroscopy.     

A family of three-dimensional porous coordination polymers with general formula (Kat)2[{M(H2O)n}3{Re6Q8(CN)6}2]·xH2O (Q=S, Se; n=1.5, 2)

The X-ray crystal structures of a series of new compounds (H₃O)₂[{Mn(H₂O)_1.5}₃{Re₆Se₈(CN)₆}₂]·19H₂O (1), (Me₄N)₂[{Co(H₂O)_1.5}₃{Re₆S₈(CN)₆}₂]·13H₂O (2), (Me₄N)₂[{Co(H₂O)_1.5}₃{Re₆Se₈(CN)₆}₂]·3H₂O (3), (Et₄N)₂[{Mn(H₂O)₂}₃{Re₆Se₈(CN)₆}₂]·6.5H₂O (4), (Et₄N)₂[{Ni(H₂O)₂}₃{Re₆S₈(CN)₆}₂]·6.5H₂O (5), and (Et₄N)₂[{Co(H₂O)₂}₃{Re₆S₈(CN)₆}₂]·10H₂O (6) are reported. All six compounds are isostructural crystallizing in cubic space group with four formulae per unit cell. For compounds 1, 3-5 the following parameters were found: (1) a=19.857(2) Å, R1=0.0283; (3 at 150 K) a=19.634(1) Å, R1=0.0572; (4) a=20.060(2) Å, R1=0.0288; (5) a=19.697(2) Å, R1=0.0224. The structures consist three-dimensional cyano-bridged framework formed by cyano cluster anions [Re₆Q₈(CN)₆]⁴⁻, Q=S, Se and transition metal cations, M²⁺=Mn²⁺, Co²⁺, Ni²⁺. Water molecules and large organic cations Me₄N⁺ and Et₄N⁺ are included in cavities of this framework. Porosity of the framework, its ability to accommodate different cations and water molecules by little changes in the structure, as well as distortion of coordination framework under loss of water of crystallization is discussed.     

Synthesis,characterization, and biological activity of Cd(II) and Mn(II) coordination polymers based on pyridine-2,6-dicarboxylic acid

The coordination polymers (CPs) {[Cd(Pydc)(H₂O)₃] · PydcH₂} (I) and [Mn(Pydc)(H₂O)₃] · PydcH2} (II) were obtained by the reaction of CdSO₄ · 5H₂O or MnCl₂ · 4H₂O with pyridine-2,6-dicarboxylic acid (PydcH₂). The structures of the CPs I and II were characterized by IR, UV-Vis, TGA, and X-ray single crystal analysis (CIF files CCDC nos. 1417757 (I), 1417758 (II)). The network structures of I and II are constructed by an infinite number of discrete binuclear molecules and free PydcH2. The structures of the CPs I and II connected by the extensive H-bonds and π–π stacking, forming a 3D-network. The CPs I and II were screened to test their antimicrobial activities against different species of bacteria and fungi.     

Polymeric gold(I) diisobutyl dithiophosphate, [Au2{S2P(O-iso-C4H9)2}2]n: Synthesis,supramolecular self-organization (a role of aurophilic interaction), 13C and 31P MAS NMR spectroscopy,and thermal behavior

A new polymeric gold(I) diisobutyl dithiophosphate (Dtph), [Au₂{S₂P(O-iso-C₄H₉)₂}₂] _n (I), was preparatively obtained and characterized by ¹³C and ³¹P MAS NMR spectroscopy and X-ray diffraction (CIF file CCDC no. 977818). Diagrams of the χ² statistic were constructed from the complete ³¹P MAS NMR spectra and used to calculate the ³¹P chemical shift anisotropy (δ _aniso = δ _zz ? δ _iso ) and the asymmetry parameter η = (δ _yy ? δ _xx )/(δ _zz ? δ _iso ). The main structural unit of complex I is the noncentrosymmetric dinuclear molecule [Au₂{S₂P(O-iso-C₄H₉)₂}₂], in which the gold atoms are linked by two bridging ligands Dtph. The central cyclic structural fragment of the dimer [Au₂S₄P₂] is additionally stabilized by the intramolecular aurophilic interaction Au?Au. Further supramolecular self-organization of the complex involves intermolecular aurophilic bonds Au?Au that serve to unite adjacent dinuclear molecules [Au₂{S₂P(O-iso-C₄H₉)₂}₂] with different spatial orientations into the polymer chains ([Au₂{S₂P(O-iso-C₄H₉)₂}₂]) _n . The thermal behavior of complex I was examined by synchronous thermal analysis under argon. The character of the thermolysis of the complex to reduced metallic gold as a final product was determined.     

Heterometallic cluster [CpMn(CO)2]2S2Ni(Dppe) containing the binuclear manganese disulfide complex as a ligand

A reaction of the disulfide complex [CpMn(CO)₂]₂S₂ with the Ni(0) diphosphine acetylene complex, (Dppe)Ni(C₂Ph₂) (I), yielded the heterometallic complex [CpMn(CO)₂]₂S₂Ni(Dppe) (II). An X-ray diffraction study revealed lateral coordination of the disulfide group to the Ni atom in complex II, which results in lengthening of both the S-S and Mn-S bonds against those in the starting complex. However, the Mn-S and Ni-S bonds are still much shorter than the sums of the covalent radii of the corresponding atoms.     

Formation of the ionic gold(III) complex [Au3{S2CN(CH2)4O}6][Au2Cl8][AuCl4] in chemisorption systems [M{S2CN(CH2)4O}2] n -[AuCl4]−/2 M HCl (M = Cd, Zn): Supramolecular structure and thermal behavior

The interaction of freshly precipitated cadmium and zinc morpholinedithiocarbamates with solutions of AuCl₃ in 2 M HCl is studied. In both cases, the heterogeneous reactions of gold(III) binding from solutions lead to the formation of the ionic gold(III) complex [Au₃{S₂CN(CH₂)₄O}₆][Au₂Cl₈][AuCl₄] (I), whose molecular and supramolecular structures are determined by X-ray diffraction analysis. Compound I includes centrosymmetric and noncentrosymmetric cations [Au{S₂CN(CH₂)₄O}₂]⁺ in a ratio of 1: 2. According to the manifested structural differences, the complex cations are related as conformers (cations A are Au(1) and cations B are Au(2)). At the supramolecular level, the isomeric cations form linear trinuclear structural fragments [Au₃{S₂CN(CH₂)₄O}₆]³⁺ [A...B...A] due to secondary bonds Au...S of 3.6364 Å. The anionic part of compound I is presented by [AuCl₄]^? and centrosymmetric binuclear [Au₂Cl₈]^2?, whose formation involved secondary bonds Au...Cl of 3.486 and 3.985 Å. The ultimate chemisorption capacity of cadmium and zinc morpholinedithiocarbamates calculated from the binding of gold(III) is 901.7 and 1010.4 mg of Au³⁺ per 1 g of the sorbent, respectively (i.e., each miononuclear fragment of the chemisorption complexes [M{S₂CN(CH₂)₄O}₂] participates in binding of two gold atoms). To establish the conditions for the isolation of bound gold, the thermal properties of compound I are studied by simultaneous thermal analysis. The thermal destruction process includes the thermolysis of the dithiocarbamate part of the complex and anions [AuCl₄]^? and [Au₂Cl₈]^2? with the reduction of gold to the metal, being the only final product of the thermal transformations of compound I.     

CP/MAS NMR (13C, 15N, and 113Cd), thermal behavior, and sorption properties of cadmium Di-iso-butyldithiocarbamate. The gold(III)-binding species sorbed from solutions

The structure and thermal behavior of cadmium di-iso-butyldithiocarbamate (I) have been studied by solid-state ¹³C and ¹⁵N CP/MAS NMR and simultaneous thermal analysis (STA). The cadmium complex forms two crystalline polymorphs, ?? and ??. The structure of each of the polymorphs contains two structurally nonequivalent binuclear [Cd₂{S₂CN(iso-C₄H₉)₂}4] molecules. The STA data have shown the possibility of the ??-I ?? ??-I phase transition. Studying the thermal behavior of the complex has demonstrated that the end product of thermodestruction is a fine yellow-orange powder of CdS. The sorption properties of I have been studied with respect to gold(III) chloride solutions in 2 M HCl. It has been found that gold(III) is efficiently sorbed from strong acid solutions in the Au³⁺ concentration range 0.032?C3.220 mg/mL. On the basis of multinuclear (¹³C, ¹⁵N, and ¹¹³Cd) MAS NMR data, it has been demonstrated that the individual gold(III)-binding species in the sorption system is the ionic gold(III) cadmium-complex of composition [Au{S₂CN(iso-C₄H₉)₂}₂]₂[CdCl₄].     

Two new cyano-bridged Cu(II)-Fe(II) complexes: Synthesis and crystal structures

Two new cyano-bridged Cu(II)-Fe(II) binuclear complexes, [Cu(L¹)Fe(CN)₅(NO)] (I) [L¹ = 1,3,6,8,11,14-hexaazatricyclo[12.2.1.1^8,11]octadecane and [Cu(L²)Fe(CN)₅(NO)] · 2H₂O (II) L² = 1,3,6,9,11,14-hexaazatricyclo[12.2.1.1^6,9]octadecane, have been assembled and structurally characterized by spectroscopy and X-ray crystallography. Complex I crystallizes in the monoclinic crystalline system of space group P2₁/c, while complex II crystallizes in the monoclinic crystalline system of space group P2₁/n. These two complexes assume a binuclear structure in which the Fe²⁺ ion is in an octahedron environment and the Cu²⁺ ion is in a square-prism geometry environment.     

Binding of Au3+ from solutions by nickel(II) and cadmium diisopropyl dithiophosphates: MAS 31P NMR, structure and thermal behavior of the polynuclear complex [Au2{S2P(O-iso-C3H7)2}2] n

The paper deals with reactions of freshly precipitated diisopropyl dithiophosphate (Dtph) complexes of nickel(II), [Ni{S₂P(O-iso-C₃H₇)₂}₂] and cadmium, [Cd₂{S₂P(O-iso-C₃H₇)₂}₄], with the [AuCl₄]^? in 2M HCl, resulting in gold transition from the solution to the precipitate as polymeric gold(I) diisopropyl dithiophosphate. The reduction of gold(III) to gold(I) noted in both cases is due to oxidation of the relevant part of the Dtph group to bis(O,O??-di-(iso)-propoxythiophosphoryl) disulfide, (iso-C₃H₇O)₂P(S)S-S(S)P(O-iso-C₃H₇)₂. The polynuclear gold(I) complex [Au₂{S₂P(O-iso-C₃H₇)₂}₂] _n (I) was isolated on a preparative scale from the chemisorption system and studied by MAS ³¹P NMR and X-ray diffraction. The key structural unit of I is the non-centrosymmetric binuclear molecule [Au₂{S₂P(O-iso-C₃H₇)₂}₂] in which the gold atoms are connected by two bridging Dtph groups. The structure contains two types of non-equivalent binuclear molecules related as conformational isomers. Owing to the relatively weak Au-Au contacts, the neighboring binuclear [Au₂{S₂P(O-iso-C₃H₇)₂}₂] molecules are involved in an infinite polymeric chain with conformer alternation along the chain. To elucidate the conditions for the recovery of bound gold(I), the precipitates formed in the sorption systems were studied by simultaneous thermal analysis under argon. As the final product, thermolysis gives reduced metallic gold. The ability of dithiophosphate complexes to bind gold from a solution is much lower than that of dithiocarbamate complexes, which is due to oxidation of some Dtph groups to disulfide.     

On rhodium(III) chloride complexes with N,N-dimethylformamide

A prolonged storage of a solution of RhCl₃·nH₂O in N,N-dimethylformamide (DMF) at room temperature is attended by the consecutive formation of two precipitates, which mainly contain the [(CH₃)₂NH₂][RhCl₅(DMF)] complex (I) and the complex [RhCl₃(DMF)₃] (II) liberates. The addition of PPh₄Cl to an aqueous solution of complex I brings about the precipitation of [PPh₄][RhCl₄(H₂O)₂] (III). Complex II (a mixture of mer-and fac-isomers) can be obtained also by treatment of [RhCl₃(CH₃CN)₃] with DMF. In the course of the latter reaction, the formation of intermediate complex [RhCl₃(CH₃CN)₂(DMF)] (IV) is observed. Complexes I–IV are characterized by elemental analysis; complexes I, II, and IV are characterized by the IR and ¹H and ¹³C NMR spectra. The structures of III and IV are determined by X-ray diffraction analysis.     

Gold(III) preconcentration from acid solutions by cadmium diisopropyldithiocarbamate: Gold(III)-binding species, supramolecular structure, and thermal properties of the heteropolynuclear complex ([Au{S2CN(iso-C3H7)2}2]2[CdCl4] · 1/2C3H6O) n

The reaction of binuclear cadmium diisopropyldithiocarbamate with a solution of AuCl₃ in 2 M HCl was studied. The heterogeneous reaction of gold(III) binding follows a chemisorption scenario (in combination with partial ion exchange) and yields a heteropolynuclear gold(III)-cadmium complex. The molecular and crystal structure of a solvated species of the compound, namely ([Au{S₂CN(iso-C₃H₇)₂}₂]₂[CdCl₄] · 1/2C₃H₆O) _n (I), was solved by X-ray crystallography. The structure of complex I contains (in the ratio 1: 1) structurally nonequivalent molecular cations [Au{S₂CN(iso-C₃H₇)₂}₂]⁺; the differences between these cations allow them to be classified as conformational isomers (cations A and B). The specifics of the supramolecular organization of complex I consist of the alternation of layers of [Au₂{S₂CN(iso-C₃H₇)₂}₄]²⁺ binuclear cations (formed by cations A), ([Au{S₂CN(iso-C₃H₇)₂}₂]⁺) _n polymer chains (formed by cations B), and [CdCl₄]^2? anions. The chemisorption capacity of the precursor cadmium diisopropyldithiocarbamate as calculated from the gold(III) binding reaction is 423.5 mg Au³⁺ per gram of sorbent. The thermal properties of complex I were studied by simultaneous thermal analysis (STA) in order for the parameters of sorbed gold recovery to be determined. The multistep thermal destruction process involves desorption of solvating acetone molecules, thermolysis of the dithiocarbamate part of the complex and [CdCl₄]^2? with release of metallic gold and cadmium chloride and formation of CdS, as well as vaporization of CdCl₂ and CdS. The only final product of thermal conversions is reduced metallic gold.     

Crystal and molecular structure of [RuNO(NO2)4OHCuPy n ] heterometallic complexes

Heterometallic complexes [RuNO(NO₂)₄OHCuPy₂(H₂O)] (I) and [RuNO(NO₂)₄OHCuPy₃] (II) are described structurally for the first time. In complex I, the ruthenium anion is coordinated to the copper atom by the bridging OH group and two bridging nitro groups; in complex II, by the bridging OH group and one bridging nitro group. Dimers are formed in the crystal lattice of complex II due to the interaction of the copper atom and the nitro group of the ruthenium anion in trans position to the bridging NO₂ group.