NATURE OF SELENOCYANATE BONDING IN THE COMPLEXES OF MM'(NCSe)4 (M=Co,Ni, Zn,Cd; M′=Zn,Cd, Hg); WITH LEWIS BASES (PART II)

Abstract

Complexes of [MM′(NCSe)₄] (M=Co, Ni, Zn, Cd; M′=Zn, Cd, Hg;) with certain ligands (L), viz., ethylenediamine(en), isonicotinic acid hydrazide(inh), 3-aminopyridine(apy), pyridine(py), pyrazine 2-carboxamide(pza), pyrazine 2–3-dicarboxamide(pzd) and tetrahydrofuran(thf) have been synthesized and characterized. Their molar conductance, magnetic moments, infrared and electronic spectral studies indicate that these complexes are of three types: (i) cationic-anionic, viz., [ML₆] [M′(NCSe)₄] (M=Ni, M′=Cd, L=inh; M=Cd, M′=Hg, L=py; and M=Zn, M′=Cd, Hg; L=en;) (ii) monomeric bridged, viz., L₄ M(NCSe)₂ M′(SeCN)₂ (M=Co, Ni; M′=Cd, Hg; L=pzd;) (iii) polymeric bridged, viz., [dbnd](SeCN)₂ L₂ M(NCSe)₂ Hg (M=Co, Ni; M′=Zn, Cd, Hg; L=thf, pza and apy). The nature of bonding in these complexes has been related to the softness difference of M and M′ and the basicity of the ligands.     

Studies on the reaction products of bis(2-furanthiocarboxyhydrazidato)m(II) with pyridine-2- and -4-carboxaldehydes

Condensation of bis(2-furanthiocarboxyhydradatometal(II), M(fth)₂; [M (II) = Mn, Fe, Co, Ni, Cu and Zn] with pyridine-2- and -4-carboxaldehydes gave complexes of the formula M(pfth)₂ [pfth? = pyridine-2-carboxaldehyde-2-furanthiocarboxyhydrazonato], Ni(Ifth)₂, Zn(Ifth)₂, Cu(Ifth) and Co(Ifth)₃, (Ifth? = pyridine-4-carboxaldehyde-2-furanthiocarboxyhydrazonato). The magnetic and electronic spectral studies coupled with photoacoustic or Mössbauer spectra suggested octahedral geometry for the M(II) complexes with low-spin states for Co(Ifth)₃ and Fe(pfth)₂. IR and ¹H NMR spectral studies of diamagnetic complexes suggested bonding through “azomethine” nitrogen and “thiolo” sulphur. IR spectra also showed the involvement of pyridine ring nitrogen in coordination in all the complexes except Cu(Itfh), Co(Ifth)₃, and Zn(Ifth)₂. Some of the compounds possessed antimicrobial activity.     

Synthese und Kristallstruktur von Hydrogenselenaten zweiwertiger Metalle – M(HSeO4)2 (M = Mg,Mn, Zn) und M(HSeO4)2 · H2O (M = Mn,Cd)

Synthesis and Crystal Structure of Hydrogen Selenates of Divalent Metals – M(HSeO₄)₂ (M = Mg, Mn, Zn) and M(HSeO₄)₂ · H₂O (M = Mn, Cd) New hydrogen selenates M(HSeO₄)₂ (M = Mg, Mn, Zn) and M(HSeO₄)₂ · H₂O (M = Mn, Cd) have been synthesized using MSeO₄ (M = Mg, Mn, Zn, Cd) and 90% selenic acid as starting materials. The crystal structures have been determined by X-ray single crystal crystallography. The compounds M(HSeO₄)₂ (M = Mg, Zn) belong to the structure type of Mg(HSO₄)₂, whereas Mn(HSeO₄)₂ forms a new structure type. Both hydrogen selenate monohydrates are isotypic to Mg(HSO₄)₂ · H₂O. In all compounds the metal atoms are octahedrally coordinated by oxygen atoms of different HSeO₄-tetrahedra. In the HSeO₄-tetrahedra the Se–OH-distances (mean value 1.70 Å) are about 0.1 Å longer than Se–O-distances (mean value 1.62 Å). In the structure of M(HSeO₄)₂ (M = Mg, Zn) there are zigzag chains of hydrogen bonded HSeO₄-tetrahedra. The structure of Mn(HSeO₄)₂ is characterized by chains of HSeO₄-tetrahedra in form of screws. Hydrogen bonds from and to water molecules connect double layers of MO₆-octahedra and HSeO₄-tetrahedra in the structures of M(HSeO₄)₂ · H₂O.     

Spectroscopic properties of some mixed ligand copper(II) complexes of N-(2-aminoethyl)-1,2-ethanediamine and ethanediamine and its alkylated derivatives

IR, EPR and electronic spectral studies have been made on a series of complexes with general formula [M(dien)L](BØ₄)₂nH₂O (M = Cu(II), Zn(II), Cd(II), dien = N-(2-aminoethyl)-1,2-ethanediamine, L = ethanediamine (en), Me₄en, Et₂en, Me = methyl, Et = ethyl, BØ₄ = tetraphenylborate, n = 0 or 2] taking copper(II) as a magnetic probe in polycrystalline and solution forms to obtain stereochemical information. A five-coordinate square-based pyramidal (SBP) geometry with CuN₃N′₂ moiety having moderately covalent metal-ligand σ-bonds is found to exist in unalkylated mixed ligand complexes. Among alkylated complexes [Cu/Cd(dien)(Me₄en)](BØ₄)₂ is found to possess two species having tetrahedral and SBP with trigonal bipyramidal distortion geometries unlike the other alkylated complexes which have indicated the presence of one species having SBP coordination geometry with varying degrees of trigonal bipyramidal distortions and metal-ligand σ-bond strengths. EPR studies in dilute dmf and pyridine solutions of copper(II) complexes indicated the presence of solute-solvent interaction.     

SYNTHESIS AND CHARACTERIZATION OF DINUCLEAR,BRIDGED COMPLEXES OF THE TYPE LxM(NCSe)2M′(SCN)2L′2

Abstract

L _x M(NCSe)₂ M′(SCN)₂(PPh₃)₂ [M=Co(II), Ni(II); M′=Hg(II), Cd(II), Zn(II); L=pyridine (py), 2,2′-bipyridyl (bipy); x=4, 2] have been synthesized. Elemental analysis, magnetic moment, electronic and infrared spectral and thermogravimetric studies indicate that these complexes are dinuclear. The total softness of M and M′ in the complexed state have also been calculated to derive certain conclusions.     

Adduct formation properties of mono- and bidentate phosphine oxide compounds in the liquid—liquid extraction of some divalent metals with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone

The bidentate phosphine oxide compounds bis(diphenylphosphinyl)methane (BDPPM) and bis(diphenylphosphinyl)ethane (BDPPE) were synthesized and the liquid—liquid extraction equilibria of some divalent metal ions such as Co(II), Ni(II), Zn(II) and Cd(II) with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP) and the neutral phosphine oxide compounds were investigated. BDPPM was found to be much more powerful than BDPPE and the monodentate neutral ligand trioctylphosphine oxide (TOPO). The composition of the extracted species were determined by a graphical method to be M(PMBP)₂(TOPO)_s (s = 2 for Co, Ni, Cd and s = 1 for Zn), M(PMBP)₂(BDPPM) and M(PMBP)₂(BDPPE). The adduct formation constants between the acylpyrazolone chelates and the neutral ligands were determined and are discussed in terms of the molecular structure.     

Reactions of 2,5-pyrrolediylbis[N-(o-hydroxyphenylaldimine)] with some metal ions

The novel Schiff-base 2,5-pyrrolediylbis[N-(o-hydroxyphenylaldimine)] (SBH₂) has been synthesized by the condensation of 2,5-pyrroledicarboxaldehyde and o-amino-phenol. The reactions of the Schiff-base with several transition- and post-transition-metal ions have been investigated. The Schiff-base reacts as a tetradentate dianion without deprotonation of the pyrrole. The complexes M(SB)·nH₂O have been isolated and characterized with n = 1, 2 or 3; SB is the dianion of the Schiff-base; and M = divalent Mn, Co, Ni, Cu, Zn, Pd, Cd, Pb or UO₂. The binuclear complexes M(SB)MX₂ for M = Cu, X = NO₃, and M = Ni or Pd, X = Cl, have also been isolated.     

NATURE OF SELENOCYANATE BONDING IN THE COMPLEXES OF [MM1(NCSe)4] (M=Co,Ni AND M1Zn,Cd, Hg) WITH CERTAIN PYPIDINE DERIVATIVES

Abstract

Complexes of [MM′(NCSe)₄] (M=Co, Ni and M′=Zn, Cd, Hg) with certain ligands(L) viz. 3-cyanopyridine, 3-aminopyridine, nicotinamide and isonicotinic acid hydrazide have been synthesized and characterized. Their molar conductance, magnetic moment, infrared and electronic spectral studies indicate that these complexes are of three types: cationic-anionic viz. [ML₆] (Zn(NCSe)₄), monomeric bridged viz. [(L₄)M(NCSe)₂Cd(SeCN)₂] and polymeric bridged viz. [dbnd](SeCN)₂L₂M(NCSe)₂Hg(SeCN)₂[dbnd]. The softness and hardness of M, M′, -N-(NCSe′) and -Se-(SeCN-) have also been calculated to derive certain conclusions.     

Group 12 metal complexes of tetradentate N2O2–Schiff-base ligands incorporating pyrazole: Synthesis,characterisation and reactivity toward S-donors,N-donors,copper and tin acceptors

New [M(Q)₂(X)] derivatives (where M=Zn, Cd or Hg; Q=1-phenyl-3-methyl-4-R(C=O)-pyrazolon-5-ato; in detail: Q_L, R=C₆H₅; Q_B, R=CH₂C(CH₃)₃; Q_S, R=CH(C₆H₅)₂; X=EtOH or H₂O) have been synthesised and characterised. These compounds undergo a condensation reaction with the appropriate diamine in ethanol, affording novel Schiff-base metal derivatives [M(diaquo)bis(1-phenyl-3methyl-4-R(C=N)-pyrazolone)(CH₂)_ndiimmine] (LⁿH₂, R=C₆H₅, n=2, 3 or 4; BⁿH₂, R=CH₂C(CH₃)₃, n=2, 3 or 4; SⁿH₂, R=CH(C₆H₅)₂, n=2 or 3; M=Zn, Cd or Hg). These compounds possess a six-coordinate metal environment. A ¹¹³Cd NMR study has been carried out on cadmium derivatives. The derivative [Zn(L²)(H₂O)₂] reacted with CuCl₂ and with Cu(ClO₄)₂ affording [Cu(Q_L)₂] and [Cu(en)₂](ClO₄)₂ (en=ethylendiamine), respectively, upon breaking of the C=N bond in the Schiff-base donor. In addition [Zn(L²)(H₂O)₂] reacted with 1,10-phenanthroline (phen), yielding the derivative [Zn(Q_L)₂(phen)]. Whereas when [Zn(L²)(H₂O)₂] reacted with CdCl₂, formation of [Cd(L²)(H₂O)₂] due to exchange of the metal centre was observed. Finally the derivative [Zn(L²)(Hmimt)], likely containing a five-coordinate ZnN₂O₂S central core, has been obtained from the exchange reaction between [Zn(L²)(H₂O)₂] and 1-methylimidazolin-2-thione (Hmimt).     

Coordination and inclusion compounds formed by addition of quinoline (Q) or isoquinoline (Iq) to a metal(II) dibenzoylmethanate (Co, Ni, Zn, Cd)

Three isomorphous series of new compounds are reported: complexes [M(DBM)₂Q₂] and [M(DBM)₂Iq₂] (M = M(II) = Co, Ni, Zn, Cd; DBM is C₆H₅COCHCOC₆H₅ ^?) and inclusion compounds [M(DBM)₂Q₂]*Q (M = Co, Zn, Cd). All the compounds comprise a trans configured octahedral complex molecule. Inclusion compounds of modified Zn and Cd DBM complexes are reported for the first time and their inclusion ability is attributed to the trans isomeric state induced by the bulky Q or Iq ligand. The TG measurements indicate the following order of thermal stability of the complexes defined by the strength of the metal–ligand bonds: Ni > Co > Cd > Zn. The inclusion compounds do not follow this trend.     

Phase Transitions in Crystalline [M(H2O)6](ClO4)2 (M=Mg,Mn, Fe,Co, Ni,Cu, Zn,Cd and Hg)

The results of DSC measurements in the temperature range 140–370 K on nine crystalline compounds of the type [M(H₂O)₆](ClO₄)₂, where M=Mg, Mn, Fe, Co, Ni, Cu, Zn, Cd and Hg, are discussed. Anomalies detected in the DSC curves are related to the existence of solid-solid phase transitions and/or to the melting points of these compounds. In consequence of two different hypothetical structural modifications of [Fe(H₂O)₆](ClO₄)₂, two DSC curves are obtained. For the compounds with M=Fe, Cd and Hg, new phase transitions have been discovered. The transition temperatures of the other phase transitions are in good agreement with literature data obtained by adiabatic calorimetry. For the compounds with M=Mg, Ni and Cd, DTA measurements were also carried out and the melting points of theses compounds were established. This revised version was published online in August 2006 with corrections to the Cover Date.     

Spectroscopic investigations and physico-chemical characterization of newly synthesized mixed-ligand complexes of 2-methylbenzimidazole with metal ions

Some mixed ligand complexes containing 2-methylbenzimidazole and thiocyanate ion were synthesized. Free ligands and their metal complexes were characterized using elemental analysis, determination of metal, magnetic susceptibility, molar conductivity, infrared, UV-VIS, and (¹H, ¹³C) NMR spectra, and X-ray structure analysis. The results suggest that the Ag(I) complex has linear geometry, Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) have tetrahedral geometry, Pd(II) complex has square planar geometry, VO(IV) square pyramidal geometry, Pb(II) irregular tetrahedral geometry, and that the Cr(III) and Mn(II) complexes have octahedral geometry. The following general formulae were proposed for the prepared complexes: [AgBX], [CrB₃X₃], (HB)₂[MnB₂X₄] · 2B and [MB₂X₂], where B = 2-methylbenzimidazole, HB = 2-methylbenzimidazolium, X = thiocyanate ion, and M = VO(IV), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Pd(II), Cd(II), and Pb(II). Molar conductance of a 10⁻³ M solution in N,N-dimethyl formamide (DMF) indicates that all the complexes are non-electrolytes except the Mn(II) complex which is an electrolyte because the molar conductivity of its solution in DMF is high.     

Four divalent metal thiocyanate coordination compounds containing a rigid functional pyridine ligand

A series of new coordination compounds Zn(SCN)₂L₂ (1), Co(SCN)₂L₂ (2), [Cd(SCN)₂L₂·2L]_n (3) and [CdHg(SCN)₄L₂]_n (4) have been prepared by self-assembly of a rigid functional pyridine ligand, trans-4-[4′-(N-methyl-N-hydroxyethyl)amimo]styryl pyridine (abbreviated as L) with M(SCN)_x (M: Zn, Co, Cd, CdHg; x: 2, 4). The crystal structures indicate that 1 and 2 are mononuclear compounds while 3 and 4 are coordination polymers. O–H?N, C–H?O, O–H?π and C–H?π hydrogen bonds play significant roles in the final crystal structures. The solid-state luminescence properties have been measured. The results indicate that the photoluminescence spectra of all the compounds can be changed by the frameworks and introducing of different metal ions.     

Synthesis, spectral and structural studies of 1-ethoxycarbonyl-piperazine-4-carbodithioate and its Co(III), Zn(II) and Cd(II) complexes

The new complexes [Co(ecpzdtc)₃] (2) [Zn(ecpzdtc)₂(py)] (3) and [Cd(ecpzdtc)₂(py)]·H₂O (4) have been synthesized from sodium 1-ethoxycarbonyl-piperazine-4-carbodithioate [(Na⁺(ecpzdtc)⁻]. The ligand and the complexes have been characterized by elemental analyses, IR, magnetic susceptibility and single crystal X-ray data. The [Zn(ecpzdtc)₂(py)] and [Cd(ecpzdtc)₂(py)]·H₂O complexes contain pyridine as the co-ligand. [Co(ecpzdtc)₃] (2) crystallizes in the monoclinic system, whereas [Zn(ecpzdtc)₂(py)] (3) and [Cd(ecpzdtc)₂(py)]·H₂O (4) crystallize in the triclinic system. The sulfur donor sites of the bidentate ligand chelate the metal center, forming a four-membered CS₂M ring. The cobalt complex has a distorted octahedral geometry, the zinc complex is almost between trigonal bipyramidal and square pyramidal, whereas the cadmium complex is square pyramidal. The crystal structures of all the complexes are stabilized by various types of inter and intramolecular hydrogen bonding.     

Polysulfonylamine. LXXXIV [1]. Zur Isotypie in den Dimesylamid-Komplexreihen [M(H2O)4{(CH3SO2)2N}2] (MMg,Ca, Ni,Cu, Zn,Cd) und [M(py)4{(CH3SO2)2N}2] (MNi,Cu, Zn,Cd)

Polysulfonylamines. LXXXIV. Isotypic Structures in the Dimesylamide Complex Series [M(H₂O)₄{(CH₃SO₂)₂N}₂] (M?Mg, Ca, Ni, Cu, Zn, Cd) and [M(py)₄{(CH₃SO₂)₂N}₂] (M?Ni, Cu, Zn, Cd) The crystal structures of the trans-octahedral complexes [M(H₂O)₄{(CH₃SO₂)₂N}₂] (M?Ca, Cd), in which the dimesylamide anion acts as a monodentate O-ligand and a tetrafunctional hydrogen bond acceptor, were determined by low-temperature X-ray diffraction. Both belong to an isotypic series (triclinic, space group P1 , Z = 1) that had previously been characterized for M?Mg, Ni, Cu and Zn (Z. Anorg. Allg. Chem. 1996 , 622, 1065). In this structure there exists an extended network of strong hydrogen bonds which is probably the underlying reason why the structure type surprisingly persists across the whole series. To support this explanation by indirect evidence from comparison with suitable structures devoid of strong hydrogen bonding, the analogous trans-octahedral complexes [M(py)₄{(CH₃SO₂)₂N}₂] (M?Mn, Co, Ni, Cu, Zn, Cd) were prepared by treating M[(CH₃SO₂)₂N]₂ with pyridine, and the crystal structures of the Ni, Cu, Zn and Cd compounds were studied by low-temperature X-ray crystallography. As anticipated, the four pyridine complexes do not form an isotypic series but instead two isotypic pairs consisting of the Ni and Zn compounds (monoclinic, space group P2₁/n, Z =2) and of the Cu and Cd complexes (triclinic, space group P1, Z = 1). All molecules of the aqua and the pyridine complexes display crystallographic centrosymmetry. In the hydrates, the mean M? OH₂ and the M? O(anion) distances are 232.6 and 232.7 pm for M ? Ca, 225.5 and 230.3 pm für M ? Cd. The mean M? N and the M? O(anion) bond lengths of the pyridine species amount to 211.8 and 213.1 pm for M ? Ni, 217.0 and 218.5 pm for M ? Zn, 232.8 and 234.4 pm for M ? Cd; the corresponding values for the severely Jahn-Teller distorted Cu complex are 203.6 and 254.5 pm. In the crystals of the pyridine complexes, each methyl group is connected through a weak C? H…?O bond to a sulfonyl oxygen atom of an adjacent molecule.     

Diphosphine derivatives: Part 5. Ligand behaviour and vibrational spectra of coordinated tetraalkyl-1,2-dithioxodi-λ5-phosphanes (tetraalkyldiphosphine disulphides)

Vibrational data are reported for complexes of tetraethyl-,tetrapropyl-and tetrabutyl-1,2-dithioxodi-λ⁵-phosphanes (tetraalkyldiphosphine disulphides) P₂R₄S₂ with zinc, cadmium, mercury and cobalt halides. The P—P stretching frequencies in the coordinated ligands occur near 500 cm^?1, substantially higher than in the corresponding P₂Me₄S₂ complexes, most probably because of interactions with P—C—C deformation modes. In the F—C stretching region the spectra of the P₂Et₄S₂ complexes are consistent with (but do not necessarily prove) cis-chelate ligand geometry with Zn, Cd and Co halides, and gauche-chelate geometry with Hg halides. No M—S stretching vibrations can be identified above 250cm^?1.     

THE PREPARATION AND CHARACTERIZATION OF Cd(XCN)4M TYPE COMPOUNDS

Abstract

A series of compounds of the type Cd(XCN)₄M (X=S and Se; M=Mn, Fe, Co and Zn) have been prepared and characterized. These compounds crystallize in the tetragonal system: space group I4[sbnd]S₄ ². The bidentate thiocynate and selenocyanate ligands coordinate to the “hard” M(II) ions through the nitrogen atom and the “soft” Cd(II) ion through the sulfur or selenium atom. The Cd[sbnd]Se bond in Cd(XCN)₄ M is slightly stronger than the Cd[sbnd]S bond while the M[sbnd]NCSe bond is slightly weaker than the M[sbnd]NCS bond. The M(II) ions tetrahedrally coordinated by the nitrogen end of XCN^? are in the high spin state. The [sbnd]NCS and [sbnd]NCSe ligands are located at about the same place in the spectrochemical series.     

Trimellitate complexes of divalent transition metals with hydrazinium cation

New dihydrazinium divalent transition metal trimellitate hydrates of empirical formula (N₂H₅)₂M(Html)₂·nH₂O, where n = 1 for M = Co or Ni, and n = 2 for M = Mn, Zn, or Cd (H₃tml = trimellitic acid), and monohydrazinium cadmium trimellitate, [(N₂H₅)Cd(Html)_1.5·2H₂O] have been prepared and characterized by physico-chemical methods. Electronic spectroscopic, and magnetic moment data suggest that Co and Ni complexes adopt an octahedral geometry. The IR spectra confirm the presence of monodentate carboxylate anion (Δν = ν_asy(COO^?) ? ν_sym(COO^?) > 190 cm^?1) and coordinated N₂H₅ ⁺ ion (ν_N–N 1015 ? 990 cm^?1) in all the complexes. All the complexes undergo endothermic decomposition eliminating CO₂ in the temperature region 200–250 °C, followed by exothermic decomposition (in the range of 500–570 °C) of organic moiety to give the respective metal carbonate as the end products except nickel and cobalt complexes, which leave respective metal oxides. X-ray powder diffraction patterns reveal that Ni and Co complexes are isomorphous as are those of, Zn(II) and Cd(II) of the type, (N₂H₅)₂M(Html)₂·2H₂O.     

New homoleptic metal complexes of Schiff bases derived from 2,4-di-p-tolyl-3-azabicyclo[3.3.1]nonan-9-one

New bidentate Schiff-base ligands 2-(2,4-di-p-tolyl-3-azabicyclo[3.3.1]nonan-9-ylidene)hydrazinecarbothioamide HL¹ and 2-(2,4-di-p-tolyl-3-azabicyclo[3.3.1]nonan-9-ylidene)hydrazinecarboxamide HL² were synthesized from the condensation of 2,4-di-p-tolyl-3-azabicyclo[3.3.1]nonan-9-one with thiosemicarbazide and semicarbazide, respectively. Homoleptic complexes of these ligands, of general formula K[Cr(L ⁿ )₂Cl₂], K₂[Mn(L ⁿ )₂Cl₂], K₂[Fe(L¹)₂Cl₂] and [M(L ⁿ )₂] (where M = Co(II), Ni(II) Cu(II), Zn(II), Cd(II), and Hg(II) ions; n = 1 or 2) are reported. The mode of bonding and overall geometry of the complexes were determined through IR, UV-Vis, NMR and mass spectral studies, magnetic moment measurements, elemental analysis, metal content, and conductance. These studies revealed octahedral geometry for Cr(III), Mn(II), and Fe(II) complexes, square planar for Cu(II), Co(II), and Ni(II) complexes and tetrahedral for Zn(II), Cd(II), and Hg(II) complexes.     

An Infrared Spectroscopic Study on the Hofmann T d -Type Clathrates: M(Imidazole) 2 M'(CN) 4 .2C 6 H 6

Infrared spectra of M (Imidazole)2 M' (CN)₄ 2C₆H₆ (M = Mn, Co,Ni, Cd; M' = Zn, Cd) are reported. The spectral data suggest that the clathratesare similar in host structure to of Hofmann T_d-type clathrates.