N2S2 macrocyclic ligands. Synthesis and characterization of novel transition metal complexes of the type [LM(Si2Me6NH)2]2+ and [L′M(Si2Me6NH)2]2+

Summary Novel N₂S₂ macrocyclic ligands, L and L [SS-diethyl(1,3-diaminopropane) dithiocarbamate], [SS-cyclohexyl spiro-(1,3-diaminopropane) dithiocarbamate] and their complexes with Mn^II, Fe^II, Co^II, Ni^II and Cu^II have been characterized by elemental analyses, conductivity measurements, i.r., u.v.-vis. and n.m.r. spectra. The divalent transition metal complexes appear to be square planar and achieve octahedral geometry when treated with bis(trimethylsilyl)-amine to yield new heterobimetallic complexes.     

Synthesis of Bis(macrocyclic) Polyamines Containing Rigid Bridging Groups

Thesgnthesi8ofbis(macrocyclic)POlyamineligandsandtheirdinuclearcomplexesoftransitionmetalionshaveattractedmuchinterestinrecentyears.Andava-rietyofsyStemshavebeenreported[1-s1.Theprotonatedfreeligandshavebeenusedashostsforanionicsubstrates.Theresultingdinuc1earcomplexeshavebeenstudiedasmodelsfortheactivesitesofphosphateases.Ofspecialinterestisthehydrolysisofactivatedphosphatemonoester[3J.Here,weconfineourreporttothesrothe8isofthreenew8ymmetricalbis(1,4,7-triazacyclononane)ligandsNa-ccontaini…     

Organotin(IV) complexes with 2-(2′-pyridyl)quinoxaline (L): The crystal structure of the [SnEt2Cl2L]·0.5 benzene

Complexes of 2-(2′-pyridyl)quinoxaline (L) with R₂SnCl₂ (R=Me, Et, Buⁿ) have been synthesized and characterized using IR, far-IR, ¹¹⁹Sn Mössbauer, ¹H and ¹³C spectroscopies. The X-ray crystal structure of Et₂SnCl₂L shows a bidentate chelating behaviour of L, which is observed in all the diorganotin compounds presented. Interaction of the ligand L with SnCl₄ resulted in the formation of a salt with the formula [(LH)₂]²⁺[SnCl₆]²⁻. Solution studies of the complexes R₂SnCl₂L (R=Me, Et, Buⁿ) revealed partial dissociation of the ligand in chloroform.     

Copper(II), nickel(II) and palladium(II) complexes of the diamide ligand N,N′-bis(2-carbamoylethyl)ethylenediamine (H2L) and the crystal structure of the carbonyl-oxygen-bonded copper(II) complex [Cu(H2L)](ClO4)2

The preparation of the diamide ligand N,N-bis(2-carbamoylethyl)ethylenediamine (H2L) by Michael addition of ethylenediamine to acrylamide is described. The copper(II) complex [Cu(H2L)](ClO4)2 and the deprotonated complex [CuL]·H2O have been prepared and characterized as has the blue octahedral nickel(II) complex [Ni(H2L)](ClO4)2. The crystal structure of the carbonyl-oxygen-bonded copper(II) complex [Cu(H2L)] (ClO4)2 has been determined (R=5.5%). The stepwise protonation equilibria of the ligand have been studied by potentiometric titration, giving values of logK1= 8.71 and logK2=5.74 at 25°C and I=0.1moldm–3 (NaClO4). The interaction of copper(II) with the ligand (H2L/Cu(II)=1:1) can be fitted to the set of equilibria:With nickel(II), only two complexes, [Ni(H2L)]2+ and [NiL], occur and they have formation constants of log110=7.39 and log 11–2=–11.49. With palladium- (II) the system is similar to that with copper(II) with three complex species, 110, 11–1 and 11–2, with log 110=15.48, log 11–1=11.88 and log 11–2=7.32.     

New tetraaza macrocyclic complexes of palladium(II) and platinum(II) formed by the self-condensation of 5-amino-3-methyl-1-phenylpyrazole-4-carbaldehyde in the presence of metal ions. α-Amino ether and carbinolamine derivatives of the macrocyclic Schiff base metal complex

The self-condensation of 5-amino-3-methyl-1-phenylpyrazole-4-carbaldehyde (AMPC) in the presence of Pd^II and Pt^II ions yields the Pd^II and Pt^II complexes, [M(TAAP)]Cl₂, of the fully cyclized tetradentate macrocyclic ligand tetrapyrazolo[1,5,9,13]tetraazacyclohexadecine, (TAAP). Metathetical displacement of the chloride has led to isolation a series of complexes of the type [M(TAAP)]X₂, (X=I, ClO₄ and BF₄), the formulation of which is supported by elemental analysis, molar conductance and magnetic susceptibility measurements, and i.r. and u.v.–vis. spectra. Spectroscopic and other analytical results reveal that the complexes have square-planar stereochemistry with four donor nitrogen atoms coordinated to the metal ion in a planar array. The reaction which produces this new cyclic ligand is assumed to include the metal ion acting as a template for the condensation. Thus the probable mechanistic implications for the coordination template hypothesis are discussed to explain the formation of these new macrocyclic chelate compounds. Both Pd^II and Pt^II complexes appear to be sensitive to nucleophilic attack at the methine carbon, which is reversible upon acidification. The reaction of [Pt(TAAP)]²⁺ or [Pd(TAAP)]²⁺ with MeO^- or EtO^- ions results in the formation of partially solvolysed inner complexes containing two ionized -amino ether functions, stabilized by the macrocyclic chelate ring. Attempts to prepare discrete -carbinolamine derivatives were unsuccessful.     

A study of zinc complexes of the metalloligand [Pt2(μ-S)2(PPh3)4] of the type [Pt2(μ-S)2(PPh3)4ZnL]+ (L = bidentate chelating ligand)

Reactions of [Pt₂(μ-S)₂(PPh₃)₄] with zinc acetate and an ancillary chelating ligand L (HL = 8-hydroxyquinoline, 8-tosylaminoquinoline or maltol) with added trimethylamine in methanol give new cationic platinum–zinc sulfide aggregates [Pt₂(μ-S)₂(PPh₃)₄ZnL]⁺, isolated as their BF₄^? salts. The complexes were characterized by NMR spectroscopy, ESI mass spectrometry, microelemental analysis, and an X-ray structure determination of the tosylamidoquinoline derivative [Pt₂(μ-S)₂(PPh₃)₄Zn(TAQ)]BF₄, which showed a distorted tetrahedral coordination geometry at zinc. Additional examples, containing picolinate, dithiocarbamate, or dithiophosphinate ligands were also synthesized and partly characterized in order to demonstrate a wider range of available derivatives.     

A study on some macrocyclic bicopper(Ⅱ) complexes as the model compounds of superoxide dismutase

24-Membered macrocyclic bicopper(Ⅱ) complexes wth bridging ligand imidzao-late,SCN-,N3-and H2O respectively were synthesized by condensation of diacetylpyridine with 3-oxapentane-1,5-diamine.As the model compounds of superoxide dismutase (SOD),the relationship between their SOD activities and properties of bridging ligands and redox potentials of copper(Ⅱ) were studied.     

Synthesis of optically active Zn(II) complexes with thiosemicarbazones of (+)-camphor (L) and (−)-carvone (L1). The crystal structures of L and [Zn(L)2Cl2]

The optically active complexes [Zn(L)₂Cl₂] (I) and [Zn(L¹)₂Cl₂] (II) (L and L¹ are thiosemicar-bazones of (+)-camphor and (?)-carvone, respectively) were obtained. The crystal structures of L and complex I were determined by X-ray diffraction. The structure of L consists of hydrogen-bonded molecules united into chains. The crystal structure of complex I is built from mononuclear molecules. The coordination polyhedron of the Zn atom is a distorted tetrahedron Cl₂S₂. The molecule L functions as a monodentate ligand. According to data from IR spectroscopy, complex II is structurally similar to complex I.     

Electrochemical studies of the bis (triphenyl phosphine) ruthenium(II) complex,cis -[RuCl2(L)(PPh3)2], with L = 2-(2′-pyridyl)quinoxaline

Electrochemical studies of the newly synthesized bis(triphenyl phosphine) ruthenium(II) complex, cis-[RuCl₂(L)(PPh₃)₂] (1, with L = 2-(2′-pyridyl)quinoxaline, C₁₃N₃H₉), were performed in acetonitrile (ACN). For this purpose, cyclic voltammograms (CVs) as well as electrochemical impedance spectra (EIS) were recorded on either glassy carbon (GC), platinum (Pt), gold (Au), or multi-walled carbon nanotube (MWCNT) electrodes. Qualitative examination of solutions of 1 in ACN was performed on the basis of conductivity measurements and electrospray ionization mass spectrometry (ESI–MS). The conductivity data suggest that 1 is a 1 : 1 type electrolyte in ACN. The ESI spectra further demonstrate that upon dissolution of 1 in ACN progressive replacement of chloro- and PPh₃-ligands by ACN occurs, leading to formation of [RuCl(L)(PPh₃)(CH₃CN)₂]⁺Cl^?, [2 ⁺ Cl ^? ]. The CVs recorded for [2 ⁺ Cl ^? ] on various working electrodes demonstrate that the reversibility of the redox couple 2^{2 +/+} enhances with the order: Au < Pt < MWCNT < GC. The EI spectra verify that GC and MWCNT electrodes provide insignificant barrier for interfacial electron transfer since they afford less charge-transfer resistance.     

Co(III) and Cr(III) complexes of diphosphadithia ligands and the crystal structure of [CoCl2(L3)]PF6·CH2Cl2 (L3=Ph2P(CH2)2S(o-C6H4)S(CH2)2PPh2)

[CrX₃(thf)₃] (X=Cl or Br) reacts with L (L=L¹–L³ or Ph₂[14]aneP₂S₂) (L¹=Ph₂P(CH₂)₂S(CH₂)₂S(CH₂)₂PPh₂, L²=Ph₂P(CH₂)₂S(CH₂)₃S(CH₂)₂PPh₂, L³=Ph₂P(CH₂)₂S(o-C₆H₄)S(CH₂)₂PPh₂, Ph₂[14]aneP₂S₂=4,8-diphenyl-1,11-dithia-4,8-diphosphacyclotetradecane) and TlPF₆ in MeNO₂ solution to yield the distorted octahedral complexes [CrX₂(L)]PF₆ as green coloured solids in high yield. UV/visible spectroscopy suggests that these are cis-dihalo species and they have also been characterised by IR spectroscopy, electrospray mass spectrometry and microanalyses. The Co(III) analogues [CoX₂(L)]⁺ are readily prepared in a two-stage reaction, involving treatment of CoX₂·6H₂O with L (L=L¹–L³) and NH₄PF₆ in EtOH solution to give a green/brown solid, followed by halogen oxidation of this product in CH₂Cl₂ solution using X₂/CCl₄, to give the final products as brown coloured solids. A mixture of PF₆⁻ and [CoX₄]²⁻ anions are present in the final Co(III) compounds in varying ratios. Crystal structures of [CoCl₂(L²)]₂[CoCl₄]·4H₂O and [CoCl₂(L³)]PF₆·CH₂Cl₂ confirm tetradentate P₂S₂ coordination of L in each case, with mutually cis halogens completing the distorted octahedral geometry. In both cases the complex cation adopts the cis-α form in the solid state and this is also consistent with the solution ³¹P{¹H} NMR spectroscopic data. ⁵⁹Co NMR spectroscopy reveals a very broad single resonance at ≈3200 ppm for these species.     

Mössbauer analysis of substituted diiron(II) tetraiminediphenolate macrocyclic complexes

A new series of substituted diiron(II) complexes [Fe(2)(tidf)(L)(2)(MeOH)(2)](n+) (tidf=a two compartment tetraiminediphenolate macrocycle; n=0 or 2+; L=NCS(-), CN(-), N(3)(-), pyrazine (pz), 4-cyanopyridine (4-cnpy) and 4-mercaptopyridine (4-shpy)) and one tetranuclear complex, {[Fe(2)(tidf)(CH(3)OH)(2)](2)(mu-4-cnpy)(2)}(ClO(4))(4) were isolated and characterized by elemental analysis, conductivity measurements, M?ssbauer and FTIR.     

Inhibiting the growth of tumor cells by ruthenium(II) complexes [Ru(phen)2L] (L = o-TFMPIP and p-CPIP) through DNA-binding

[Ru(phen)₂o-TFPIP]²⁺ (1) and [Ru(phen)₂p-CPIP]²⁺ (2) have been synthesized and demonstrated to inhibit the growth of tumor cells. The inhibitory activities (IC₅₀) of 1 against the growth of C6, MDA-MB-231 and HepG2 cells were about 24.5, 36.7, and 36.1 μM, respectively. Studies show that both complexes bind to CT-DNA, explained by using density functional theory calculations. The LogP calculated for 1 and 2 are ?0.4859 and ?1.279, respectively. These complexes, especially 1, can be used as promising inhibitors in chemotherapy, and their DNA-binding behaviors play a key role.     

Cobalt (iron) thiolato complexes containing the Co-ligand phosphine and reaction products of the structural fragment ML 2 L′ (L = 1,2-bidentate thiolate,L′= tertiary phosphine)

Mono-, di-, tri-, and tetra-nuclear cobalt (iron) complexes containing co-ligands phosphine and thiolate are presented according to the classification by combination of different dentates of the two ligands. Emphasis is being put on the triand tetranuclear cluster complexes of monodentate phosphines and 1,2-bidentate thiolates. These complexes are considered to be constructed based on the general structural fragment (or building block) ML ₂L (L=1,2-bidentate thiolate,L=tertiary phosphine). Structural regularities are presented in Tables I, III, IV, and V and discussed. FAB mass spectroscopic data showed the possible fragmentation patterns. Synergism of the cluster skeletons is proposed to explain the occurrence of the distinct structural modes.Abbreviations Bu _n ³ P tri-n-butylphosphine - dmpe 1,2-bis(dimethylphosphino)ethane - dmpm 1,2-bis(dimethylphosphino)methane - dppe 1,2-bis(diphenylphosphino)ethane - dppep bis(2-diphenylphosphinoethyl)phenylphosphine - dppm 1,1-bis(diphenylphosphino)methane - dppp 1,3-bis(diphenylphosphino)propane - Et₃P triethylphosphine - Ph₃P triphenylphosphine - tepme 1,1,1-tris(diethylphosphinomethyl)ethane - tppme 1,1,1-tris(diphenylphosphinomethyl)ethane - H₂bdt 1,2-benzenedithiol - H₂edt 1,2-ethanedithiol - Hmbt 2-mercaptobenzothiazole - H₂mp 2-mercaptophenol - Hmp 2-hydroxythiophenolate - Hmpo 2-mercaptopyridine-N-oxide - H₂mpp 2-mercapto-3-hydroxypyridine - Hmpp 3-hydroxy-2-pyridinothiolate - H₂pdt 1,2-propanedithiol - HSPh thiophenol - H₂tdt 4-methyl-1,2-benzenedithiol(4-toluenedithiol) - R₂dtc dialkyldithiocarbamate - (RO)₂dtp dialkyldithiophosphate     

The coordination chemistry of mono and bis(di-2-pyridylamine)copper(II) complexes: preparation,characterization and crystal structures of [Cu(L)(NO2)2], [Cu(L)(H2O)2(SO4)], [Cu(L)2(NCS)](SCN)·0.5DMSO and [Cu(L)2(SCN)2]

The crystal structures of two mono(dpyam)copper(II) complexes, [Cu(dpyam)(NO₂)₂] (1) and [Cu(dpyam)(H₂O)₂(SO₄)] (2) and two dithiocyanate compounds containing bis(dpyam)copper(II) units, [Cu(dpyam)₂(NCS)](SCN)·0.5DMSO (3) and [Cu(dpyam)₂(SCN)₂] (4) have been determined by X-ray crystallography. The second orthorhombic form of the monomeric Cu(II) complex 1 was obtained by the reaction of di-2-pyridylamine (dpyam) with CuCl and NaNO₂ in water–methanol solution. Each copper(II) ion in 1 exhibits a tetrahedrally-distorted square base of the CuN₂O₂ chromophore, with off-the-z-axis coordinated nitrito groups weakly bound in approximately axial positions. Complex 2 is an example of a polymeric copper(II) derivative containing the bidentate bridging sulfate ligand in the long-bonded axial positions. Each copper(II) ion in 2 shows an elongated tetragonal octahedral stereochemistry. The CuN₄N′ chromophore of 3 involves a square-based pyramidal structure, slightly distorted towards a trigonal bipyramidal stereochemistry, τ=0.13. One of the SCN⁻ anions is bonded to the copper(II) ion via the N atom in the axial position of the square pyramid. Complex 4 is centrosymmetric and octahedrally elongated, with the SCN⁻ anions coordinating in axial positions via the S atom. The structures of complexes 1–4 and their ESR and electronic reflectance spectra are compared with those of related complexes.     

Outer-sphere addition compounds of MoO2Br2(H2O)2 with ethers. Molecular structure of MoO2Br2(H2O)2·L (L=2,5,8-trioxanonane; 2,5,8,11,14-pentaoxapentadecane)

Outer-sphere addition compounds of MoO₂Br₂(H₂O)₂ with diethyl ether, dioxane, glyme, diglyme, triglyme and tetraglyme have been readily prepared by crystallizing diethyl ether extracts of a solution of sodium molybdate in concentrated hydrobromic acid in the presence of the corresponding ether. The molecular structures of MoO₂Br₂(H₂O)₂·L (L=2,5,8-trioxanonane; 2,5,8,11,14-pentaoxapentadecane) have been established by X-ray diffraction analysis.     

Synthesis and crystal structure of [UO2(L)(OH)], (CN3H6)2[(UO2)2CrO4(L)4 · 2H2O and [UO2(H2O)5][(UO2)2Cr2O7(L)4] (where L is picolinate ion)

[[UO₂(L)(OH)] (I), (CN₃H₆)₂[(UO₂)₂CrO₄(L)₄] · 2H₂O (II), and [UO₂(H₂O)₅][(UO₂)₂Cr₂O₇(L)₄] (III) crystals, where L is picolinate ion C₅H₄NCOO^?, have been synthesized and studied by X-ray diffraction and IR spectroscopy. Complex I crystallizes in triclinic system with the unit cell parameters a = 6.2858(5) Å, b = 7.9522(5) Å, c = 8.3598(6) Å, α = 79.527(6)°, β = 87.760(6)°, γ = 79.126(6)°, space group P $\bar 1$ , Z = 2, R = 0.0306, and complexes II and III crystalize in monoclinic system with a = 8.8630(9) Å, b = 13.4540(13) Å, c = 31.266(3) Å, β = 93.118(3)°, space group C2/c, Z = 4, R = 0.0187 (II), and a = 7.3172(4) Å, b = 15.4719(8) Å, c = 16.6534(10) Å, β = 98.943(4)°, space group P2₁/m, Z = 2, R = 0.0588 (III). The structure of complex I is built of electronegative [UO₂(L)(OH)] chains, which belong to the AT¹¹M² crystallochemical group (A = UO ₂ ²⁺ , T¹¹ = L, M² = OH^?) of uranyl complexes. The structure of complexes II and III contains [(UO₂)₂(L′)(L)₄]^2? dimers (L′ = CrO ₄ ^2? or Cr₂O ₇ ^2? ), which belong to the A₂B²B ₄ ⁰¹ group (A = UO ₂ ²⁺ ,B² = L′, B⁰¹ = L). The specifics of intermolecular interactions in the structures of complexes I–III and some their analogues have been considered using molecular Voronoi-Dirichlet polyhedra.     

Facile synthesis of nanoparticles of the molecule-based superconductor κ-(BEDT-TTF)2Cu(NCS)2

Well-dispersed roughly spherical nano-objects of the molecule-based superconductor κ-(BEDT-TTF)₂Cu(NCS)₂ have been prepared in an organic solution by using an easy synthetic route. Long alkyl-chain aconitate esters have been used as growth controlling agents. Nano-objects exhibiting sizes in the 35–120 nm range are made of aggregated individual smaller nanoparticles ranging from 3 to 10 nm. Nanoparticle powders have been studied by X-ray diffraction, high resolution electron microscopy and atomic force microscopy in the conductivity mode.     

Varying the Lewis base coordination of the Y2N2 core in the reduced dinitrogen complexes {[(Me3Si)2N]2(L)Y}2(μ-η2:η2-N2) (L = benzonitrile, pyridines, triphenylphosphine oxide, and trimethylamine N-oxide)

The effect of the neutral donor ligand, L, on the Ln(2)N(2) core in the (N═N)(2-) complexes, [A(2)(L)Ln](2)(μ-η(2):η(2)-N(2)) (Ln = Sc, Y, lanthanide; A = monoanion; L = neutral ligand), is unknown since all of the crystallographically characterized examples were obtained with L = tetrahydrofuran (THF). To explore variation in L, displacement reactions between {[(Me(3)Si)(2)N](2)(THF)Y}(2)(μ-η(2):η(2)-N(2)), 1, and benzonitrile, pyridine (py), 4-dimethylaminopyridine (DMAP), triphenylphosphine oxide, and trimethylamine N-oxide were investigated. THF is displaced by all of these ligands to form {[(Me(3)Si)(2)N](2)(L)Y}(2)(μ-η(2):η(2)-N(2)) complexes (L = PhCN, 2; py, 3; DMAP, 4; Ph(3)PO, 5; Me(3)NO, 6) that were fully characterized by analytical, spectroscopic, density functional theory, and X-ray crystallographic methods. The crystal structures of the Y(2)N(2) cores in 2-5 are similar to that in 1 with N-N bond distances between 1.255(3) ? and 1.274(3) ?, but X-ray analysis of the N-N distance in 6 shows it to be shorter: 1.198(3) ?.     

Accessibility and Selective Stabilization of the Principal Spin States of Iron by Pyridyl versus Phenolic Ketimines: Modulation of the (6)A(1) ↔ (2)T(2) Ground-State Transformation of the [FeN(4)O(2)](+) Chromophore

Several potentially tridentate pyridyl and phenolic Schiff bases (apRen and HhapRen, respectively) were derived from the condensation reactions of 2-acetylpyridine (ap) and 2'-hydroxyacetophenone (Hhap), respectively, with N-R-ethylenediamine (RNHCH(2)CH(2)NH(2), Ren; R = H, Me or Et) and complexed in situ with iron(II) or iron(III), as dictated by the nature of the ligand donor set, to generate the six-coordinate iron compounds [Fe(II)(apRen)(2)]X(2) (R = H, Me; X(-) = ClO(4)(-), BPh(4)(-), PF(6)(-)) and [Fe(III)(hapRen)(2)]X (R = Me, Et; X(-) = ClO(4)(-), BPh(4)(-)). Single-crystal X-ray analyses of [Fe(II)(apRen)(2)](ClO(4))(2) (R = H, Me) revealed a pseudo-octahedral geometry about the ferrous ion with the Fe(II)-N bond distances (1.896-2.041 ?) pointing to the (1)A(1) (d(π)(6)) ground state; the existence of this spin state was corroborated by magnetic susceptibility measurements and M?ssbauer spectroscopy. In contrast, the X-ray structure of the phenolate complex [Fe(III)(hapMen)(2)]ClO(4), determined at 100 K, demonstrated stabilization of the ferric state; the compression of the coordinate bonds at the metal center is in accord with the (2)T(2) (d(π)(5)) ground state. Magnetic susceptibility measurements along with EPR and M?ssbauer spectroscopic techniques have shown that the iron(III) complexes are spin-crossover (SCO) materials. The spin transition within the [Fe(III)N(4)O(2)](+) chromophore was modulated with alkyl substituents to afford two-step and one-step (6)A(1) ? (2)T(2) transformations in [Fe(III)(hapMen)(2)]ClO(4) and [Fe(III)(hapEen)(2)]ClO(4), respectively. Previously, none of the X-salRen- and X-sal(2)trien-based ferric spin-crossover compounds exhibited a stepwise transition. The optical spectra of the LS iron(II) and SCO iron(III) complexes display intense d(π) → p(π)* and p(π) → d(π) CT visible absorptions, respectively, which account for the spectacular color differences. All the complexes are redox-active; as expected, the one-electron oxidative process in the divalent compounds occurs at higher redox potentials than does the reverse process in the trivalent compounds. The cyclic voltammograms of the latter compounds reveal irreversible electrochemical generation of the phenoxyl radical. Finally, the H(2)salen-type quadridentate ketimine H(2)hapen complexed with an equivalent amount of iron(III) to afford the μ-oxo-monobridged dinuclear complex [{Fe(III)(hapen)}(2)(μ-O)] exhibiting a distorted square-pyramidal geometry at the metal centers and considerable antiferromagnetic coupling of spins (J ≈ -99 cm(-1)).