Heterocyclic thiocarboxylato complexes of iron: synthesis,characterization, electrochemistry,and reactions

Heterocyclic-thiocarboxylato complexes of iron, CpFe(CO)₂SCO-het (het?=?2-C₄H₃O, 2-C₄H₃S, CH₂-2-C₄H₃S), have been synthesized via the reaction of iron sulfides, (μ-S _x )[CpFe(CO)₂]₂ (x?=?3,?4), with heterocyclic acid chlorides het-COCl. Photolytic substitutions of these complexes CpFe(CO)₂SCO-het with triphenylphosphine, triethylphosphite, triphenylarsine, and triphenylantimony [ER₃ (E?=?P, R?=?Ph, OC₂H₅; E?=?As, Sb, R?=?Ph)] exclusively gave the monosubstituted complexes CpFe(CO)(ER₃)SCO-het in good yields. The new complexes have been characterized by elemental analysis, UV-Vis, IR, ¹H, and ³¹P NMR spectroscopies and by cyclic voltammetry for a representative family (1, 4a–d). The solid state structures of CpFe(CO)₂SCO(2-C₄H₃S) (2), CpFe(CO)(PPh₃)SCO(2-C₄H₃S) (5a), CpFe(CO)(AsPh₃)SCO(2-C₄H₃S) (5b), and CpFe(CO)(SbPh₃)SCO(2-C₄H₃S) (5c) were determined by X-ray crystal structure analysis.     

Synthesis and Characterization of Novel Trans-Mixed Diamine Platinum(II) and Platinum(IV) Complexes

A series of novel trans-mixed diamine platinum(II) and platinum(IV) complexes of type trans-[Pt^II(R-NH₂)(R'-NH₂)Cl₂] and trans -[Pt^IV(R-NH₂)(R'-NH₂)Cl₄] (where R-NH₂ = ethylamine or butylamine and R'-NH₂ = methylamine, propylamine, isopropylamine, pentylamine, or hexylamine) was synthesized and characterized using elemental analysis and infrared and ¹⁹⁵Pt nuclear magnetic resonance spectroscopic techniques.     

Complex Salts Derived from the Reactions of Organotin(IV) with 6-Methylpyridine-2-Carboxaldehyde Phenylhydrazone: X-Ray Crystal Structure of BIS[6-Methylpyridine- 2-Carboxaldehydehydrazodium]- Tetrachlorodimethylstannate(IV)

Reactions of organotin(IV) chloride (Me 2 SnCl 2 , PhSnCl 3 and n -BuSnCl 3 ) with the Schiff base 6-methylpyridine-2-carboxaldehyde phenylhydrazone ( L ) result in the formation of organotin(IV) anionic complexes. Me 2 SnCl 2 reacts with L in dichloromethane to form [ L H + ] 2 [Me 2 SnCl 4 ] 2 m . X-ray structural analysis has been carried out on the complex salt bis[6-methylpyridine-2-carboxaldehydehydrazodium]tetra-chlorodimethylstannate(IV), [ L H + ] 2 [Me 2 SnCl 4 ] 2 m wherein the tin moieties exist as monomers. Reactions of PhSnC1 3 and n -BuSnCl 3 with L form the complexes [ L H + ] 2 [PhSnCl 5 ] 2 m and [ L H + ] 2 [ n- BuSnCl 5 ] 2 m . Compounds were also characterized by FTIR, 1 H and 13 C NMR spectroscopy.     

Reactions of bis(diphenylphosphine)acetylene with metal carbonyl complexes

The reaction of [Co₂(CO)₈] with DPPA at room temperature yields a diphosphine bridged product [Co₄(CO)₁₂(μ-Ph₂-P-C≡C-P-Ph₂)₂] 1. Heating of 1 at 45°C promoted cleavage of the P-C_sp bond with the formation of binuclear, phosphido-bridged σ-π-acetylide isomer complexes [Co₂(CO)₅(μ-PPh₂) (μ-σ-π-C≡C-PPh₂ )] 2a, 2b. Heating (60°C) of the complex [CpFe(CO)₂CH₃] and DPPA affords mono and binuclear acetyl, P-coordinated diphenylphosphinoalkyne metal complexes [CpFe(Ph₂P-C≡C-PPh₂)CO(COCH₃)] 3, [CpFeCO(COCH₃)]₂-μ-(Ph₂P-C≡C-PPh₂) 4.     

SINGLET-TRIPLET SPIN TRANSITION IN AN IRON(II) COMPLEX OF 1,10-PHENANTHROLINE-2-CARBOTHIOAMIDE

Abstract

The ⁵⁷Fe Mössbauer effect for the solid complex FeLCl₂·H₂O (L=10-phenanthroline-2-carbothioamide) has been studied between 4.2°K and 298°K. Two overlapping doublets (I and II) are observed, their relative intensity being strongly temperature dependent. The doublets are characterized by δE_Q(I)=0.53 mm sec^?1, δ^IS(I)=+ 0.22 mm sec^?1 and δE_Q(II)=1.33 mm sec^?1, δ^IS(II)=+0.23 mm sec^?1 at 4.2°K. In conjunction with magnetic data, the Mössbauer spectra are interpreted in terms of a singlet-triplet spin transition of the central iron(II) ion. In an applied magnetic field at 4.2°K, H_int=0, V_ZZ(I)>0, and V_ZZ(II)>0. The results are consistent with optical electronic and infrared vibrational spectra.     

Complexation of (1Z, 2Z)- N ′-1-, N ′-2-dihydroxy- N -1-, N -2-dipyridin-2-ylethanedimidamide in mono and dinuclear Zn(II), Cd(II), Hg(II) and Sn(IV) complexes

Mononuclear O,O-coordinated complexes K₂(MLCl₂) M = Zn(II), Cd(II) and dinuclear complexes (MZnLCl₂R₂)^x along with dinuclear N,N-coordinated complexes (M′ZnH₂LCl₂R₂)^y (where M = Zn(II), Cd(II), Hg(II) and M′ = M and Sn(IV); R = Cl, CH₃; x = 0, ?2; y = 0, +2) of N′-1-,N′-2-dihydroxy-N-1-,N-2-dipyridin-2-ylethanedimidamide (H₂L) have been prepared. All complexes have been characterized by ¹H NMR, IR, EI-mass spectroscopy and elemental microanalysis. These results are in agreement with our prediction for structures of mono and dinuclear complexes of H₂L and L^?2 with Zn(II) in the gas phase by theoretical studies.     

Synthesis,characterization and antineoplastic activity of 5-chloro-2,3-dihydroxypyridine transition metal complexes

Synthetic procedures are described that allow access to cis-[Mo₂O₅(cdhp)₂]^2?, cis-[W₂O₅(Hcdhp)₂], trans-[OsO₂(cdhp)₂]^2?, trans-[UO₂(Hcdhp)₂], [ReO(PPh₃)(Hcdhp)₂]X (X =?Cl, I), [ReO₂(cdhp)₂]^?, [M(PPh₃)₂(cdhp)], [M(bpy)(cdhp)] (M(II) =?Pd, Pt), [Ru(YPh₃)₂(Hcdhp)₂] (Y =?P, As), [Rh(Hcdhp)₂Cl(H₂O)], [Rh(PPh₃)₂(Hcdhp)₂]ClO₄ and [Ir(bpy)(cdhp)Cl₂], where Hcdhp, cdhp are the deprotonated monoanion of 5-chloro-3-hydroxypyrid-2-one and dianion of 5-chloro-2,3-dihydroxypyridine, respectively. These complexes were characterized by their Raman, IR, ¹H NMR, electronic and mass spectra, conductivity, magnetic and thermal measurements. H₂cdhp, cis-K₂[Mo₂O₅(cdhp)₂], [Pd(bpy)(cdhp)] display a significant antineoplastic activity against Ehrlich ascites tumor cells (EAC).     

Synthesis and Characterization of Nitrato-Triamine-Metal(II) Complexes. Conglomerate Crystallization Part 55. Crystal Structure of [Ni(dien)(O2NO)(ONO2)] (I), {[Cu(dien)-(μ-ONO2)]NO3}∞ (II), [Zn(dien)(O2NO)(ONO2)] (III), [Ni(Medpt)(O2NO)(ONO2)] (IV) and [Cu(Medpt)(ONO2)2] (V)

In absolute ethanol and in the presence of triethylorthoformate, reactions of metal(II) nitrates with linear tridentate amines afforded metal complexes of the formula M(NNN)(NO₃)₂, where M = Ni²⁺, Cu²⁺ and Zn²⁺, and NNN = dien and Medpt. The compounds fall into three categories in accordance with their stereochemistry and mode of binding of the nitrato ligands. Compounds I, [Ni(dien)(O₂NO)(ONO₂)] and III, [Zn(dien)(O₂NO)(ONO₂)] are isomorphous and isostructural. They crystallize in the monoclinic space group P2₁/n with nearly identical cell constants. The stereochemistry of these two compounds is such that the terdentate dien ligand forms a fac MN₃ moiety with the two oxygens of the bidentate nitrato ligand trans to the terminal NH₂. These ligands form the base of the octahedral arrangement in which the sixth position, trans to the secondary nitrogen of the dien, is an oxygen of the monodentate nitrato ligand. Compound IV, [Ni(Medpt)(O₂NO)(ONO₂)] falls into the same category as I and III despite the fact that the two rings in the Ni-Medpt moiety are six-membered rings, unlike those in compounds I and III which are five-membered rings. Nevertheless, the nickel-amine arrangement is fac. The bidentate nitrato-oxygens are trans to the terminal NH₂ of the amine ligand, and the oxygen of the monodentate nitrato ligand is trans to the tertiary amine-nitrogen. Such stereochemistry is prevalent for nickel and zinc compounds. Interestingly, compound IV crystallizes as a conglomerate (space group P2₁2₁2₁). Compound II, {[Cu(dien)(μ-ONO₂)]NO₃}_∞ belongs to the second category and has a polymeric structure. The repeating fragment in the polymeric chain is a Cu(dien)-O fragment with the monodentate nitrato ligand occupying an equatorial position of the base. A second oxygen of the equatorial nitrate becomes an axial ligand for an adjacent Cu-N₃O fragment. In this way the substance propagates into an infinite chain. The repeating unit has an effective square pyramidal, five-coordinate, configuration. Finally, the compound crystallizes as a racemate. The second nitrate necessary for charge compensation of this copper(II) compound is ionic and its function is to hold the infinite chains of the lattice. The third category represented by compound V, [Cu(Medpt)(ONO₂)₂] contains two molecules in the asymmetric unit of the racemic lattice (monoclinic, space group P2₁/a). The structure of Cu-Medpt is unlike that of IV in that both species present in the asymmetric unit have the amine ligand in a mer configuration which together with a monodentate oxygen of a nitrato ligand form a base plane of a square pyramid. The fifth ligand of both Cu²⁺ ions is a second monodentate nitrato ligand. The stereochemical differences between the two Cu²⁺ ions are insignificant for the Cu-Medpt fragment, which share the same conformation and configuration. The major difference between the two species is the torsional angles defined by the Cu-O-N-O angles. The difference arises from variation in the hydrogens of the primary amine moieties selected by nitrato-oxygens to form intramolecular hydrogen bonds. Finally, there is a little variation in the equatorial Cu-ONO₂ stereochemistry because of steric hindrance, imposed by the Medpt, preventing large torsional angles by these nitrato ligands. This is evident by comparing the two copper species shown in Finally, nitrate-to-Br ligand exchange was found to take place when KBr pellets are prepared for IR spectral measurements.     

Equilibrium and spectroscopic studies of ternary cadmium(II) and mercury(II) complexes with CMP and triamines

Formation of ternary Cd(II) and Hg(II) complexes with cytidine 5′-monophosphate (CMP) and triamines has been studied. Complexes M(CMP)(H _x PA) and M(CMP)(PA) (M?=?Cd, Hg; PA?=?polyamine) were detected and overall stability constants and equilibrium constants for their formation determined. The mode of coordination in the complexes has been proposed on the basis of the equilibrium and ¹³C, ³¹P NMR and IR studies. In the Hg(II) systems, metalation involves the donor endocyclic N(3) atom, the CMP phosphate group and nitrogen donor atoms of PA. Relative to the Hg/CMP binary systems, the presence of a polyamine in ternary systems does not change the metal–nucleotide mode of coordination. In ternary systems including Hg(II) ions, the occurrence of noncovalent interactions has not been detected. Cd(II) ions form molecular complexes as well as protonated species. Introduction of a polyamine to the Cd/CMP system changes the coordination mode of the nucleotide. The phosphate group of CMP is inactive in binary complexes (metalation by the N(3) atom) but is involved in coordination in heteroligand species. In contrast to other polyamines studied, in the system including 1,7-diamino-4-azaheptane (3,3-tri), the phosphate group of CMP in Cd(CMP)(H3,3-tri) does not participate in metalation but is engaged in intramolecular noncovalent interactions that stabilize the complex.     

Complexation of N-tris[(1,2-dicarboxyethoxy)ethyl]amine with Ca(II), Mn(II), Cu(II) and Zn(II) in aqueous solution

In a search for environmentally friendly metal chelating ligands for industrial applications, the protonation and complex formation equilibria of N-tris[(1,2-dicarboxyethoxy)ethyl]amine (TCA6) with Ca(II), Mn(II), Cu(II) and Zn(II) ions in aqueous 0.1?M NaCl solution were studied at 25°C by potentiometric titration. A model for complexation and stability constants of the complexes were determined. With all of the metals, complex formation was dominated by ML^4?. Comparison of TCA6 and six other chelating agents showed TCA6 to be suitable for applications where strong calcium binding is essential.