Complexes of N-thiophosphorylthioureas RNHC(S)NHP(S)(OiPr)2 (HL) (R = pyridin-2-yl, pyridin-3-yl, 6-amino-pyridin-2-yl) with copper(I): Crystal structures of Cu(PPh3)nL (n = 1, 2)

Reaction of the potassium salts of N-thiophosphorylated thioureas of common formula RNHC(S)NHP(S)(OiPr)₂ [R = pyridin-2-yl (HL^a), pyridin-3-yl (HL^b), 6-amino-pyridin-2-yl (HL^c)] with Cu(PPh₃)₃I in aqueous EtOH/CH₂Cl₂ leads to mononuclear [Cu(PPh₃)₂L^a,b-S,S′] (1, 2) and [Cu(PPh₃)L^c-S,S′] (3) complexes. Using copper(I) iodide instead of Cu(PPh₃)₃I, polynuclear complexes [Cu_n(L-S,S′)_n] (4-6) were obtained. The structures of these compounds were investigated by IR, ¹H, ³¹P{¹H} NMR spectroscopy, ES-MS and elemental analyses. The crystal structures of Cu(PPh₃)₂L^b (2) and Cu(PPh₃)L^c (3) were determined by single-crystal X-ray diffraction.     

Rhenium(III) and technetium(III) complexes with 2-mercapto-1,3-azole ligands and X-ray crystal structures

Reactions of labile [MCl₃(PPh₃)₂(NCMe)] (M = Tc, Re) precursors with 1H-benzoimidazole-2-thiol (H₂L¹), 5-methyl-1H-benzoimidazole-2-thiol (H₂L²) and 1H-imidazole-2-thiol (H₂L³), in the presence of PPh₃ and [AsPh₄]Cl gave a new series of trigonal bipyramidal M(III) complexes [AsPh₄]{[M(PPh₃)Cl(H₂L^1-3)₃]Cl₃} (M = Re, 1-3; M = Tc, 4-6). The molecular structures of 1 and 3 were determined by X-ray diffraction. When the reactions were carried out with benzothiazole-2-thiol (HL⁴) and benzoxazole-2-thiol (HL⁵), neutral paramagnetic monosubstituted M(III) complexes [M(PPh₃)₂Cl₂(L^4,5)] (M = Re, 8, 9; M = Tc, 10, 11) were obtained. In these compounds, the central metal ions adopt an octahedral coordination geometry as authenticated by single crystal X-ray diffraction analysis of 8 and 11. Rhenium and technetium complexes 1, 4 and rhenium chelate compounds 8, 9 have been also synthesized by reduction of [MO₄]⁻ with PPh₃ and HCl in the presence of the appropriate ligand. All the complexes were characterized by elemental analyses, FTIR and NMR spectroscopy.     

Synthesis, structure, and properties of monomeric Fe(II), Co(II), and Ni(II) complexes of neutral N-(aryl)-2-pyridinecarboxamides

We have prepared and structurally characterized six-coordinate Fe(II), Co(II), and Ni(II) complexes of types [M^II(HL¹)₂(H₂O)₂][ClO₄]₂ (M = Fe, 1; Co, 3; and Ni, 5) and [M^II(HL²)₃][ClO₄]₂ · MeCN (M = Fe, 2 and Co, 4) of bidentate pyridine amide ligands, N-(phenyl)-2-pyridinecarboxamide (HL¹) and N-(4-methylphenyl)-2-pyridinecarboxamide (HL²). The metal centers in bis(ligand)-diaqua complexes 1, 3 and 5 are coordinated by two pyridyl N and two amide O atoms from two HL¹ ligands and six-coordination is completed by coordination of two water molecules. The complexes are isomorphous and possess trans-octahedral geometry. The metal centers in isomorphous tris(ligand) complexes 2 and 4 are coordinated by three pyridyl N and three amide O atoms from three HL² ligands. The relative dispositions of the pyridine N and amide O atoms reveal that the pseudo-octahedral geometry have the meridional stereochemistry. To the best of our knowledge, this work provides the first examples of structurally characterized six-coordinate iron(II) complexes in which the coordination is solely by neutral pyridine amide ligands providing pyridine N and amide O donor atoms, with or without water coordination. Careful analyses of structural parameters of 1-5 along with that reported in the literature [M^II(HL¹)₂(H₂O)₂][ClO₄]₂ (M = Cu and Zn) and [Co^III(L²)₃] have allowed us to arrive at a number of structural correlations/generalizations. The complexes are uniformly high-spin. Spectroscopic (IR and UV/Vis) and redox properties of the complexes have also been investigated.     

Synthesis and single crystal structures of first examples of tridentate ligands of (Te, N, S) type and their complexes with palladium(II), platinum(II) and ruthenium(II)

The First examples of (Te, N, S) type ligands, 2-CH₃SC₆H₄CHNCH₂CH₂TeC₆H₄-4-OCH₃ (L¹) and 2- CH₃SC₆H₄CHNHCH₂CH₂TeC₆H₄-4-OCH₃ (L²), and their metal complexes, [PdCl(L¹)]PF₆ · CHCl₃ · 0.5H₂O (4), [PtCl(L¹)]PF₆ (5), [PdCl(L²)]ClO₄.CHCl₃ (6), [PtCl(L²)]ClO₄ (7), and [Ru(p-cymene)(L²)](PF₆)₂ · CHCl₃ (8), have been synthesized and characterized. The single crystal structures of 4, 6 and 8 have revealed that both the ligands coordinate in them in a tridentate (Te, N, S) mode. The geometry around Pd in both the complexes has been found to be square planar, whereas for Ru in a half sandwich complex 8, it is found to be octahedral. Between two molecules of 4 there are intra and inter molecular weak Te?Cl [3.334(3) and 3.500(3) Å, respectively] interactions along with weak intermolecular Pd?Te [3.621(2) Å] interactions. The Pd-Te bond lengths are between 2.517(6) and 2.541(25) Å and the Ru-Te bond length is 2.630(6) Å. The crystal structure of [PdCl₂(4-MeO-C₆H₄- TeCH₂CH₂NH₂)] (9) is also determined. It is formed when KPF₆ is not added in the synthesis of 4 and Pd-complex of L¹ is recrystallized. Apart from Te?Cl secondary interactions, C-H?π interactions also exist in the crystal of 9.     

Synthesis and characterisation of palladium(II) and platinum(II) compounds containing pyrazole-derived ligands: crystal structure of [PdCl2(HL)] (HL = 3-phenyl-5-(2-pyridyl)pyrazole)

Reaction of the ligands 3-phenyl-5-(2-pyridyl)pyrazole (HL¹), 3,5-bis(2-pyridyl)pyrazole (HL²), 3-methyl-5-(2-pyridyl)pyrazole (HL³) and 3-methyl-5-phenylpyrazole (HL⁴) with [MCl₂(CH₃CN)₂] (M = Pd(II), Pt(II)) or [PdCl₂(cod)] gives complexes with stoichiometry [PdCl₂(HL)₂] (HL = HL¹, HL², HL³), [Pt(L)₂] (L = L¹, L², L³) and [MCl₂(HL⁴)₂] (M = Pd(II), Pt(II)). The new complexes were characterised by elemental analyses, conductivity measurements, infrared and ¹H NMR spectroscopies. The crystal and molecular structure of [PdCl₂(HL¹)] was resolved by X-ray diffraction, and consists of monomeric cis-[PdCl₂(HL¹)] molecules. The palladium centre has a typical square planar geometry, with a slight tetrahedral distortion. The tetra-coordinated metal atom is bonded to one pyridine nitrogen, one pyrazolic nitrogen and two chloro ligands in a cis disposition. The ligand HL¹ is not completely planar.     

Copper(I)-imine complexes: Synthesis and catalytic activity in olefin cyclopropanation

Different imine-type ligands, prepared by the condensation of anilines or of α-methylbenzylamine with 2-pyridinecarboxaldehyde (pyim^1,2) or 2-quinolinecarboxaldehyde (quim^1,2) were prepared. These species act as N,N′-bidentate, chelating ligands upon coordination to Cu(I): treatment of [Cu(PPh₃)₃Cl] with an equimolar amount of the ligands resulted in the displacement of two molecules of PPh₃, giving rise to the formation of [Cu(pyim^1,2)(PPh₃)Cl] (1-2) and [Cu(quim^1,2)(PPh₃)Cl] (3-4), respectively. The copper derivatives 1-4 proved to be highly active catalysts in olefin cyclopropanation in the presence of ethyl diazoacetate, even using deactivated olefins (namely, 2-cyclohexen-1-one) as substrate. The X-ray structure of complex 2, [Cu(pyim²)(PPh₃)Cl], is also reported.     

New ruthenium complexes from Ru3(CO)12 and 6-Alkyl- or 6-Phenyl-2-hydroxypyridines

Trirutheniumdodecacarbonyl (Ru₃(CO)₁₂) reacts with 2-hydroxy-6-methylpyridine and with 2-hydroxy-5,6,7,8-tetrahydroquinoline in toluene to form centrosymmetric tetranuclear complexes of the type [Ru(η², μ-L)(CO)₂(μ₃-L)Ru(CO)₂]₂, where L is the respective (N,O)-pyridonate ligand (2 and 3). The structures of these complexes, which are almost insoluble in all common solvents, could be determined by single-crystal X-ray diffraction. Reaction of Ru₃(CO)₁₂ with 2-hydroxy-4,6-diphenylpyridine in methanol includes ortho-metallation at the phenyl ring, furnishing the dinuclear complex [Ru(κ²N,C-L)(CO)₂(μ-OCH₃)₂Ru(CO)₂ (κ²N,C-L)] (4), where L = (2-(6-hydroxy-4-phenylpyridin-2-yl)phenyl), according to an X-ray crystal structure determination.     

Structure, spectra and electrochemistry of ruthenium-carbonyl complexes of naphthylazoimidazole

[Ru(H)(CO)(PPh₃)₂(α/β-NaiR)](ClO₄) (3, 4) are synthesized by the reaction of [Ru(H)(Cl)(CO)(PPh₃)₃] with 1-alkyl-2-(naphthyl-α/β-azo)imidazole (α-NaiR (3); β-NaiR (4)). One of the complexes [Ru(H)(CO)(PPh₃)₂(α-NaiMe)](ClO₄) (3a) has been structurally established by X-ray diffraction study. Upon addition of Cl₂ saturated in MeCN to 3 or 4 gives [Ru(Cl)(CO)(α/β-NaiR)(PPh₃)₂](ClO₄) (for α-NaiR (5); β-NaiR (6)), without affecting metal oxidation state, which were characterized by spectroscopic measurements. The redox property of the complexes is examined by cyclic voltammetry.     

Osmadisiloxane and osmastannasiloxane complexes derived from silanolate complexes of osmium(II)

Treatment of the five-coordinate chlorodimethylsilyl complex, Os(SiMe₂Cl)Cl(CO)(PPh₃)₂ with hydroxide readily produces Os(SiMe₂OH)Cl(CO)(PPh₃)₂ (1). Complex 1 is deprotonated by ^tBuLi giving the silanolate complex, Os(SiMe₂OLi)Cl(CO)(PPh₃)₂ (2), which reacts further with Me₃SiCl or Me₃SnCl to give Os(SiMe₂OSiMe₃)Cl(CO)(PPh₃)₂ (3) or Os(SiMe₂OSnMe₃)Cl(CO)(PPh₃)₂ (4), respectively. The structures of 3 and 4 have been determined by X-ray crystallography. Reaction between OsH(κ²-S₂CNMe₂)(CO)(PPh₃)₂ and HSiMe₂Cl gives Os(SiMe₂Cl)(κ²-S₂CNMe₂)(CO)(PPh₃)₂ (5). This six-coordinate chlorodimethylsilyl complex, is unreactive towards hydroxide at room temperature and at 60 °C forms Os[Si(OH)₃](κ²-S₂CNMe₂)(CO)(PPh₃)₂ (7). Complex 5 is, however, smoothly converted to the hydroxy derivative, Os(SiMe₂OH)(κ²-S₂CNMe₂)(CO)(PPh₃)₂ (6) upon chromatography on silica gel. Complex 6 is deprotonated by ^tBuLi giving the intermediate silanolate complex, Os(SiMe₂OLi)(κ²-S₂CNMe₂)(CO)(PPh₃)₂, which reacts further with Me₃SiCl to give Os(SiMe₂OSiMe₃)(κ²-S₂CNMe₂) (CO)(PPh₃)₂ (8). Crystal structure determinations for 5, 6, 7, and 8 have been obtained and structural comparisons of these related compounds are made.     

Reactions of 2-(arylazo)aniline with iridium trichloride: Synthesis, characterization and structure of new cyclometallated complexes of iridium(III)

Reactions of 2-(arylazo)aniline, HL (H represents the dissociable protons upon orthometallation and HL is p-RC₆H₄NNC₆H₄-NH₂; RH for HL¹; CH₃ for HL² and Cl for HL³) with IrCl₃ in methanol afforded orthometallated complexes of composition (L)(HL)IrCl₂ (2) and (L)(MeOH)IrCl₂ (3), respectively. Complex (L)(MeOH)IrCl₂ (3) converted into (L)(CH₃CN)IrCl₂ (4) upon refluxing in acetonitrile. The X-ray structure of the complexes (L¹)(HL¹)IrCl₂ (2a) and (L³)(CH₃CN)IrCl₂ (4c) have been determined and characterized unequivocally. The anionic L⁻ binds the metal in tridentate (C, N, N) manner for all the complexes.     

New ruthenium(II) precursors with the tetradentate sulfur macrocycles tetrathiacyclododecane ([12]aneS4) and tetrathiacyclohexadecane ([16]aneS4) for the construction of metal-mediated supramolecular assemblies

The preparation and structural characterization of several new Ru(II) complexes in which four coordination positions are occupied by the sulfur atoms of a macrocycle, either 1,4,7,10-tetrathiacyclododecane ([12]aneS4) or 1,5,9,13-tetrathiacyclohexadecane ([16]aneS4), and the two others by relatively labile ligands (Cl⁻, , H₂O, dmso-S), are described:cis-[Ru([12]aneS4)(dmso-S)(H₂O)](CF₃SO₃)₂ (2a), cis-[Ru([12]aneS4)(dmso-S)(ONO₂)](NO₃) (2b), cis-[Ru([16]aneS4)Cl₂] (4), and trans-[Ru([16]aneS4)(dmso-S)(H₂O)](CF₃SO₃)₂ (5).The complexes of the larger [16]aneS4 macrocycle have a flexible coordination geometry, either cis or trans, that makes them unsuited for being used as precursors in metal-driven self-assembly processes.On the contrary, the [12]aneS4 complexes cis-[Ru([12]aneS4)(dmso-S)Cl]Cl (1) and, above all, its chlorido free derivatives cis-[Ru([12]aneS4)(dmso-S)(H₂O)](CF₃SO₃)₂ (2a) and cis-[Ru([12]aneS4)(dmso-S)(ONO₂)](NO₃) (2b) are potential precursors of the geometrically stable 90° bis-acceptor fragment cis-[Ru([12]aneS4)]²⁺.Preliminary results of their reactivity towards the linear linker pyrazine (pyz) showed that the nature of the isolated product depends on that of the counter-anion.When treated with pyz 2b afforded the dinuclear complex [{Ru([12]aneS4)(ONO₂)}₂(μ-pyz)](NO₃)₂ (8), while 2a gave the molecular triangle [{cis-Ru([12]aneS4)(μ-pyz)}₃](CF₃SO₃)₆ (9), both in low yields.The X-ray structures of compounds 2a, 2b, 4, 5, [{Ru([12]aneS4)Cl}₂(μ-pyz)]Cl₂ (7), 9, and of the sandwich complex[Ru([12]aneS3-S)₂](CF₃SO₃)₂ (3), in which only three sulfur atoms of each macrocycle are bound to ruthenium, are also described.     

Molecular structures and redox properties of oxorhenium(V) ‘3+1’ mixed ligand complexes with heterocyclic thiolates containing nitrogen

Reactions of chloro(3-thiapentane-1,5-dithiolato)oxorhenium(V) [ReO(SSS)Cl] with N-methyl-1H-imidazole-2-thiol (HL¹) and 2-pyrimidinethiol (HL²) have been studied to form ‘3+1’ oxorhenium(V) complexes. In the absence of triethylamine, [Re(SSS)(HL¹)]Cl (1a) was formed, while in the presence of triethylamine [Re(SSS)L¹] (1b) and [Re(SSS)L²] (2) were produced. Molecular structures of complexes 1a and 2 were determined to be distorted square pyramidal by single crystal X-ray analytical method. From cyclic voltammetric studies, furthermore, it was proposed that complexes 1b and 2 are irreversibly oxidized to Re(VI) at around 0.84 and 1.01 V versus Ag/AgNO₃, respectively, and are reduced to Re(IV) at −1.55 and −1.51 V with the dissociation of L¹ or L², followed by the quasi-reversible reductions to Re(III) at around −1.69 V, respectively.     

Synthesis and characterization of ruthenium(II) complexes bearing the bis(2-pyridylmethyl)amine ligand

The reaction of [Ru(CO)₂Cl₂]_n with bis(2-pyridylmethyl)amine (bpma) in refluxing ethanol followed by anion exchange yields two products: cis,fac-[Ru(bpma)(CO)₂Cl]PF₆ (1a, 71%) and trans,fac-[Ru(bpma)(CO)₂Cl]PF₆ (1b, 29%). Reaction of 1a with AgBF₄ in acetone, followed by acetonitrile and then anion exchange gave cis,fac-[Ru(bpma)(CO)₂(CH₃CN)](PF₆)₂ (2a). In the same way, 1b afforded trans,fac-[Ru(bpma)(CO)₂(CH₃CN)](PF₆)₂ (2b). Reaction of depolymerized [Ru(CO)₂Cl₂]_n with bpma in ethanol at room temperature afforded cis,cis-[Ru(η²-bpma)(CO)₂Cl₂] (3). In refluxing ethanol, 3 was converted to cis,fac-[Ru(bpma)(CO)₂Cl]Cl (1a-Cl). Heating 3 in chlorobenzene afforded 1b-Cl, exclusively; heating 3 in ethylene glycol gave mainly 1a-Cl. Heating 1a-Cl in ethanol resulted in no isomerization, but heating in chlorobenzene gave a mixture of 3 and 1b-Cl. Anion exchange for PF₆ with 1a-Cl and 1b-Cl afforded 1a and 1b, respectively, whereas anion exchange for BPh₄ afforded 1a-BPh₄. Compounds 1a, 1b, 2a and 3 have been structurally characterized.     

Substituted pyridylmethylamide ligands and their zinc complexes

Mononuclear zinc complexes of a family of pyridylmethylamide ligands abbreviated as HL, HL^Ph, HL^Me3, HL^Ph3, and MeL^SMe [HL = N-(2-pyridylmethyl)acetamide; HL^Ph = 2-phenyl-N-(2-pyridylmethyl)acetamide; HL^Me3 = 2,2-dimethyl-N-(2-pyridylmethyl)propionamide; HL^Ph3 = 2,2,2-triphenyl-N-(2-pyridylmethyl)acetamide; MeL^SMe = N-methyl-2-methylsulfanyl-N-pyridin-2-ylmethyl-acetamide] were synthesized and characterized spectroscopically and by single crystal X-ray structural analysis. The reaction of zinc(II) salts with the HL ligands yielded complexes [Zn(HL)₂(OTf)₂] (1), [Zn(HL)₂(H₂O)](ClO₄)₂ (2), [Zn(HL^Ph3)₂(H₂O)](ClO₄)₂ (3), [Zn(HL^Ph)Cl₂] (4), [Zn(HL^Me3)Cl₂] (5), and [Zn(MeL^SMe)Cl₂] (6). The complexes are either four-, five- or six-coordinate, encompassing a variety of geometries including tetrahedral, square-pyramidal, trigonal-bipyramidal, and octahedral.     

First microwave-assisted synthesis of an electron-rich phosphane and its coordination chemistry with platinum(II) and palladium(II)

The P-O ligand 3-(di(2-methoxyphenyl)phosphanyl)propionic acid (HL) was synthesized by a microwave-assisted reaction of a secondary phosphane. The coordination of HL to Pt^II yielded the neutral mononuclear complex trans-[PtCl(κ²-P,O-L)(κ-P-HL)] (1), while the reaction of PdClMe(η⁴-COD) (COD = 1,4-cyclooctadiene) with HL in the presence of NEt₃ gave the anionic Pd^II compound of the formula (HNEt₃)[PdClMe(κ²-P,O-L)] (2). Upon crystallization of the latter compound the neutral chloride-bridged dimetallic compound cis-[Pd(μ-Cl)Me(HL)]₂ (3) was obtained. HL, 1 and 3·CH₂Cl₂ have been characterized by single crystal X-ray structure analyses.     

Synthesis and structures of zinc complexes with new binucleating ligands containing alkoxide bridges, and their activities in the hydrolysis of tris(p-nitrophenyl)phosphate

Four new binucleating ligands featuring a hydroxytrimethylene linker between two coordination sites (1,3-bis{N-[3-(dimethylamino)propyl]-N-methylamino}propan-2-ol, HL¹; 1,3-bis{N-[2-(dimethylamino)ethyl]-N-methylamino}propan-2-ol, HL²; 1,3-bis[bis(2-methoxyethyl)amino]propan-2-ol, HL³; and 1-bis[(2-methoxyethyl)amino]-3-{N-[2-(dimethylamino)ethyl]-N-methylamino}propan-2-ol, HL⁴) were synthesized, along with the corresponding zinc complexes. The structures of three dinuclear zinc complexes ([Zn₂L¹(μ-CH₃COO)₂]BPh₄ (1), [Zn₂L³(μ-CH₃COO)₂]BPh₄ (3), and [Zn₂L⁴(μ-CH₃COO)(CH₃COO)(EtOH)]BPh₄ (4)) and a tetranuclear zinc complex ({[Zn₂L²(μ-CH₃COO)]₂(μ-OH)₂}(BPh₄)₂ (2)) were revealed by X-ray crystallography. Hydrolysis of tris(p-nitrophenyl)phosphate (TNP) by these zinc complexes in an acetonitrile solution containing 5% Tris buffer (pH 8.0) at 30 °C was investigated spectrophotometrically and by ³¹P NMR. Although zinc complexes 1, 3, and 4 did not show hydrolysis activity, the tetranuclear zinc complex 2, containing μ-hydroxo bridges, was capable of hydrolyzing TNP. This suggests that the hydroxide moiety in the complex may have an important role in the hydrolysis reaction.     

Iron(III) complexes using NNS reduced Schiff bases and NNOS coordinating tetradentate ligands: Synthesis, structure and catecholase activity

The orange-red colored complexes of the type [Fe(L_SB)Cl₃], 1, have been synthesized in excellent yields by reacting FeCl₃·6H₂O with L_SB in methanol. Here, L_SB is (2-(ethylthio)-N-(pyridin-2-ylmethyl)ethanamine), (L_SB¹) and (2-(benzylthio)-N-(pyridin-2-ylmethyl)ethanamine) (L_SB²). Similarly, FeCl₃·6H₂O reacted with 2-(((2-(ethylthio) ethyl) (pyridin-2-ylmethyl)amino)methyl)phenol (HL¹), 2-(((2-(ethylthio)ethyl)(pyridin-2 ylmethyl)amino)methyl)-4-nitrophenol (HL²), 4-chloro-2-(((2-(ethylthio)ethyl)(pyridin-2-ylmethyl)amino)methyl)phenol (HL³), 2-(((2-(benzylthio)ethyl)(pyridin-2-ylmethyl) amino)methyl)phenol (HL⁴), 2-(((2-(benzylthio)ethyl)(pyridin-2-ylmethyl)amino)methyl) -4-nitrophenol (HL⁵), and 4-chloro-2-(((2-(benzylthio)ethyl)(pyridin-2-ylmethyl)amino) methyl)phenol (HL⁶) to give dichloro complexes of the type [Fe(L)Cl₂], 2. The solid and solution structure of the complexes, as well as their properties, were probed using X-ray diffraction, spectroscopic and electrochemical methods. The Mössbauer spectral study at 80 K for complexes reveals the existence of (III) oxidation state and high-spin state of the metal center in the complex. Dioxygenase activity of the complexes has been studied and both 1 and 2 have been found to display the intradiol-cleaving pathway. However, no extradiol cleavage products have been isolated.     

Reactions of the fac-[Re(CO)3] and [ReO] moieties with substituted benzothiazoles

The reaction of 2-(2-aminophenyl)benzothiazole (Habt) with [Re(CO)₅Br] led to the isolation of the rhenium(I) complex fac-[Re(Habt)(CO)₃Br] (1). With trans-[ReOCl₃(PPh₃)₂], the ligand Habt decomposed to form the oxofree rhenium(V) complex [Re(itp)₂Cl(PPh₃)] (2) (itp = 2-amidophenylthiolate). From the reaction of trans-[ReOBr₃(PPh₃)₂] with 2-(2-hydroxyphenyl)benzothiazole (Hhpd) the complex [Re^VOBr₂(hpd)(PPh₃)] (3) was obtained. Complexes 1-3 are stable and lipophilic. ¹H NMR and infrared assignments, as well as the X-ray crystal structures, of the complexes are reported.     

Interactions of arene-Ru(II)-chloroquine complexes of known antimalarial and antitumor activity with human serum albumin (HSA) and transferrin

The interactions of π-arene-Ru(II)-chloroquine complexes with human serum albumin (HSA), apotransferrin and holotransferrin have been studied by circular dichroism (CD) and UV-Visible spectroscopies, together with isothermal titration calorimetry (ITC). The data for [Ru(η⁶-p-cymene)(CQ)(H₂O)Cl]PF₆ (1), [Ru(η⁶-benzene)(CQ)(H₂O)Cl]PF₆ (2), [Ru(η⁶-p-cymene)(CQ)(H₂O)₂][PF₆]₂ (3), [Ru(η⁶-p-cymene)(CQ)(en)][PF₆]₂ (4), [Ru(η⁶-p-cymene)(η⁶-CQDP)][BF₄]₂ (5) (CQ: chloroquine; DP: diphosphate; en: ethylenediamine), in comparison with CQDP and [Ru(η⁶-p-cymene)(en)Cl][PF₆] (6) as controls demonstrate that 1, 2, 3, and 5, which contain exchangeable ligands, bind to HSA and to apotransferrin in a covalent manner. The interaction did not affect the α-helical content in apotransferrin but resulted in a loss of this type of structure in HSA. The binding was reversed in both cases by a decrease in pH and in the case of the Ru-HSA adducts, also by addition of chelating agents. A weaker interaction between complexes 4 and 6 and HSA was measured by ITC but was not detectable spectroscopically. No interactions were observed for complexes 4 and 6 with apotransferrin or for CQDP with either protein. The combined results suggest that the arene-Ru(II)-chloroquine complexes, known to be active against resistant malaria and several lines of cancer cells, also display a good transport behavior that makes them good candidates for drug development.     

Tuning the formation of copper(I) coordination architectures with quinoxaline-based N,S-donor ligands by varying terminal groups of ligands and reaction temperature

Five new complexes [Cu₂(L¹)I₂]_∞ (1), [Cu(L²)I]₂ (2), {[Cu₂(L²)I₂](CH₃CN)₃}_∞ (3), [Cu₂(L³)I₂]_∞ (4) and {[Cu(L³)I](CH₃CN)}₂ (5) have been obtained by reacting three structurally related ligands, 2,3-bis(n-propylthiomethyl)quinoxaline (L¹), 2,3-bis(tert-butylthiomethyl)quinoxaline (L²) and 2,3-bis[(o-aminophenyl)thiomethyl]quinoxaline (L³) with CuI, respectively, at different temperatures. Single crystal X-ray analyses show that 1, 3, 4 possess 1D chain structures, while 2 and 5 are discrete dinuclear molecules. It is interesting that the reactions of CuI with L¹ at room temperature and 0 °C, respectively, only afforded same structure of 1 (1a and 1b), while using L² (or L³) instead, two different frameworks 2 and 3 (or 4 and 5) have been obtained. The structural changes mainly resulted from the different conformations that L² or L³ adopted at different temperatures. Our research indicates that terminal groups of ligands take an essential role in the framework formation, and the reaction temperature also has important effect on the construction of such Cu(I) coordination architectures. Furthermore, the influence of hydrogen bonds on the conformation of ligands and the supramolecular structures of these complexes have also been explored. The luminescence properties of complexes 1, 2, and 4 have been studied in solid state at room temperature.