L. P. Battaglia

Synthesis, characterization and stability constant determination of l-phenylalanine ternary complexes of cobalt(II), nickel(II), copper(II) with N-heterocyclic aromatic bases and X-ray crystal structure of aqua-1,10-phenanthroline-l-phenylalaninatocopper(II) perchlorate complex

Abstract The ternary l -phenylalanine ( l -phe) complexes of Co II , Ni II and Cu II with heterocyclic bases such as 2,2′-bipyridyl (bipy) or 1,10-phenanthroline (phen) were prepared and characterized by conventional methods, IR spectroscopy, pH-metric titrations and, for [Cu(OH 2 )(phen)( l -phe)]ClO 4 , the X-ray structure was carried out: copper is in a square-pyramidal arrangement in which the base is formed by two phenanthroline nitrogens, one carboxylic oxygen and the amino nitrogen of an l -phenylalaninate ion; the apical site is occupied by a water molecule. Formation constants of Co II , Ni II and Cu II ternary complexes involving 2,2′-bipyridyl, 1,10-phenanthroline or imidazole and the bidentate l -phenylalanine were determined. The results indicate that the stability of the ternary complexes containing the same metal ion varies with the nature of the primary ligand according to the order 1,10-phenanthroline > 2,2′-bipyridyl > imidazole.

Activation of unsaturated substrates by cobalt complexes. Crystal structure and reactivity of a complex of octacarbonyl dicobalt with N-methylbis(α,α-dimethylpropargyl)amine

Abstract A new complex of octacarbonyl dicobalt with N -methyl(α,α-dimethylpropargyl)amine was prepared and characterized by spectroscopic and X-ray diffraction methods. Each triple bond is coordinated to a hexacarbonyldicobalt fragment and each metal shows a pseudo-octahedral geometry. The structure of the free ligand having NH in place of N -methyl has also been determined for comparison. Thermal decomposition of the complex in toluene or in benzonitrile afforded a series of products, mainly resulting from the rearrangement of the original complex to a metallacyclic structure, able to incorporate either the acetylenic triple bond or carbon monoxide in the case of toluene and either the acetylenic or the nitrile triple bond in the case of benzonitrile. CN bond cleavage of the starting amine was observed as a side reaction. Catalytic reactions leading to benzonitrile incorporation were also observed. A cross experiment with a 1 1 mixture of diynes, either with or without geminal methyl groups α to triple bonds showed that for conformation reasons the metallacycle moiety mainly comes from the substrate containing geminal groups, whilst for steric reasons the other substrate is preferentially incorporated into the metallacycle.

N,N?-dialkylsubstituted Imidazolidine-2-thionecopper(I) complexes. X-ray analysis of chloro-bis(N,N?-dimethylimidazolidine-2-thione)copper(I)

SummaryNew complexes of copper(I) withN,N′-dialkylsubstituted imidazolidine-2-thione ligands were prepared by reduction of CuX2 (X = Cl or Br). The i.r. spectra show that in all the complexes the ligand coordinates through the sulphur atom. The crystal structure of chloro-bis(N,N′-dimethylimidazolidine-2-thione)copper(I) has been determined from x-ray diffraction data. Crystals are monoclinic. space groupC2, with unit cell dimensions:a = 16.022(15),b = 9.942(10),c = 15.112(15) A, β = 139.84(10)2, Z = 4. The final R index is 5.2%. The copper coordination is trigonal, involving sulphur atoms of the two ligands and One chlorine atom. The steric effect of the two methyls imposes a rotation of the imidazolidine rings with respect to the coordination plane. The dihedral angle between the mean plane of thiourea moieties. parallel one with the other. and the coordination plane is 119.3°.

REACTION OF CuX2(X = Cl, Br) WITH 5,5-DIMETHYLMIDAZOLIDINE-2,4-DITHIONE (ss), AND THEIR -2-ONE-4-THIONE (oxs) AND -2-THIONE-4-ONE (sox) ISOLOGUES-CRYSTAL STRUCTURES OF CU(oxs)2Br AND Cu(ss)2Cl

Abstract Copper(I) complexes, obtained by reacting CuX2 (X = Cl, Br) with 5.5-dimethylimidazolidine-2-thione-4-one (sox), and its 2-one-4-thione (oxs) and 2,4-dithione (ss) derivatives, are reported. Infrared spectra show evidence for S-coordination in all the complexes. The crystal structure of Cu(oxs)2Br shows dimeric units, where every copper(I), practically trigonal planar, undergoes a tetrahedral distorsion by long range interactions with one bridging bromine and one bridging sulphur atom of oxs. The crystal structure of Cu(ss)2Cl is formed by a polymeric chain in which every copper has a tetrahedral environment, achieved by two ligands bridged via the two sulphur atoms between two coppers, one ligand bonded only through the 2-thione sulphur, and one chlorine. The distortions of the C=O and C=S groups from the symmetrical positions with respect to the other two bonds of the C(sp2) carbons, verified in the complexes and in the free ligands, are interpreted in terms of the VSEPR model.

X-Ray crystal structures of tetrakis(imidazolidine-2-thionato)copper(I) nitrate and dichloro-µ-imidazolidine-2-thionato-tris(imidazolidine-2-thionato)dicopper(I)

The X-ray structures of the title compounds have been determined from diffractometer data by the heavy-atom method and refined by least-squares. Crystal data: [Cu(C3H6N2S)4]NO3, (I), a= 13.22(1), b= 11.21(1), c= 7.55(1)A, α= 82.0(1), β= 78.3(1), γ= 87.2(1)°, Z= 2, space group P, final R 8.5%; [Cu(C3H6N2S)2Cl]2, (II)a= 7.43(1), b= 18.71(1), c= 16.37(1)A, β= 94.4(1)°, Z= 4, space group P21/c, final R 9.4%. In (I) copper co-ordination is tetrhedral and involves the sulphur atoms of four 2-thioimidazolidine (etu) molecules (Cu–S 2.34, 2.36, 2.34, and 2.33 A). Complex (II) is binuclear containing two kinds of CuI atoms: one tetrahedrally co-ordinated by three etu molecules (Cu–S 2.26, 2.28, and 2.63 A) and by one chlorine ion (Cu–Cl 2.32 A), the other trigonally co-ordinated by two etu molecules (Cu–S 2.20 A) and one chlorine ion (Cu–Cl 2.28 A). In both compounds conformation and packing are mainly determined by hydrogen bonds of the type N–H ⋯ O (I) or N–H ⋯ Cl (II), and N–H ⋯ S.

Structure–magnetism correlation in dimeric copper(II) carboxylates: crystal and molecular structure of tetra-µ-(propanoato-O,O′)-bis[aquacopper(II)]

The dimeric copper(II) carboxylates [{Cu(O2CR)2(H2O)}2] and [{Cu(O2CR)2}2](R = Et or Prn) have been prepared and characterized by means of spectroscopic, magnetic, and thermogravimetric analyses. For [{Cu(O2CEt)2(H2O)}2] the crystal and molecular structure has also been determined. The crystals are monoclinic, space group P21/c, with a= 15.102(7), b= 17.186(5), c= 15.190(4)A, β= 94.24(3)°, and Z= 4. Full-matrix least-squares refinement, using 1 784 independent reflections converged to a conventional R factor of 0.0561. The unit cell contains four crystallographically independent copper(II) atoms which give rise to three binuclear molecules with copper(I) acetate monohydrate type geometry. Two of these dimers are centrosymmetric with the symmetry centre at the middle of the Cu–Cu bond. Comparison of the present structural data and |2J| values with those of other structurally known dimeric copper(II) alkanoates does not allow an unambiguous determination of a specific ligand parameter to be the major factor in determining the magnitude of |2J|, and suggests that it may be the result of several modes of interaction.

The crystal and molecular structure of [bis(diphenylphosphino)ethane]tricarbonyliron(0)

Abstract [Bis(diphenylphosphino)ethane]tricarbonyliron(0), Fe9(CO)3-(Ph2PCH2CH2-PPh2), has been prepared by reducing FeCl2 with metallic manganese under an atmosphere of CO in the presence of the diphosphine at room temperature in THF. The results of an X-ray diffraction study (room temperature, Mo-Kα) are: P21/n, a 12.260(6), b 15.890(7), c 14.227(6) A, β 110.57(3)°, Z = 4, Dc 1.378, Dm 1.40 Mg m−3, Rf( 2957 413 ) = 0.0393. The iron is pentacoordinate, with a geometry intermediate between trigonal bipyramidal, with a phosphorus and a carbonyl apical, and square pyramidal with a carbonyl alpical. No significant differerences are observed between the FeP distances (av.2.224(2) A) or between the FeCO distances (av. 1.770(5) A). Comparison with the analogous bis(diphenylphosphino)methane derivative shows that the main differences in the coordination polyhedra arise from the difference in the P⋯P bite distance, which is 2.981(2) A in the ethane derivative but only 2.650(3) A in the methane derivative. The five-membered FePCCP chelate ring shows an unsymmetrical conformation, with one carbon atom tending to lie in the PFeP plane, the corresponding torsion about the FeP bond being almost zero (1.3(2)°). This kind of conformation is common for bis(diphenylphosphino)ethane chelating rings, suggesting a limited flexibility of that ring. The orientations of the phenyl groups are somewhat different from those in the corresponding bis(diphenylphosphino)methane complex.

Imidazole-containing ternary complexes of N-benzyloxycarbonyl-aminoacids. Crystal and molecular structure of bis(N-benzyloxycarbonyl-alaninato)bis-(N-methylimidazole) copper (II) ethanol solvate

Abstract Mixed ligand complexes of the type Cu(Z-aminoacidato)2(B2) (Z = benzyloxycarbonyl group, Z-aminoacidate = Z-glycinate (Zgly), Z-alaninate (Zala); Z-valinate (Zval), Z-leucinate (Zleu) ion, B = imidazole (Im), N-methylimidazole (MeIm)) were synthesized and characterized by means of electronic, infrared and EPR spectroscopies. For one of them, bis(Z-alaninato)bis(N-methylimidazole)copper(II) ethanol solvate, the crystal and molecular structure was also determined by the single crystal X-ray diffraction method. The complex crystallizes in the monoclinic space group P21/c, with cell dimensions a = 11.1119(6), b = 18.8398(7), c = 8.9652(5) A, β = 105.380(2)° and Z = 2. The structure was solved by conventional Patterson and Fourier methods and refined by full-matrix least-squares to an R value of 0.045. The complex has square-planar coordination via two centrosymmetric carboxylic oxygens and two N-methylimidazole nitrogens. The second carboxylate oxygen is 2.731(5) A from the copper atom in an ‘out of plane’ position. Packing is mainly determined by hydrogen bondings between amide nitrogen and amide carboxyl oxygen. Electronic, infrared and EPR spectra are consistent with this type of coordination geometry for anhydrous complexes, while for hydrate complexes are suggestive of tetragonal bipyramidal geometry.

One-dimensional polymeric chlorocadmate(II) systems of N-methylpiperazinium and N,N′-dimethylpiperazinium compounds: synthesis, structural and thermal properties

The chlorocadmate(II) systems of (H2me2pipz)[Cd2Cl6(H2O)2] (1) and (H2mepipz)2[Cd3Cl10(H2O)] (2) (L = me2pipz = N,N′-dimethylpiperazine; L′ = mepipz = N-methylpiperazine) were prepared and their structural and thermal properties investigated. Compound 1 is monoclinic, space group P21/c, a = 7.664(1), b = 7.472(4), c = 15.347(1) A, β = 99.468(7)°, Z = 2, R = 0.024. The crystal structure consists of organic cations and infinite one-dimensional chains of [CdCl3(H2O)]n3− anions. Each Cd atom is octahedrally surrounded by bridged and terminal chlorine atoms and by a water molecule, which is in trans position with respect to the terminal chlorine atom. Inter- and intrachain hydrogen bond interactions between the terminal chlorine atoms and the water molecules contribute to the crystal packing. Compound 2 is orthorhombic, space group Cmc21, a = 15.286(3), b = 13.354(3), c = 13.154(3) A, R = 0.023. The crystal structure consists of organic dications and infinite chains of [Cd2Cl6(CdCl4H2O]n4− units running along the [001] axis. Each unit is formed of regularly alternate six-coordinated Cd atoms, one of them linking one pentacoordinated Cd atom which completes its coordination througha water molecule. A strong hydrogen bond interaction involving the organic dication and the inorganic chain contributes to the crystal packing. Differential hydrogen bond interaction involving the organic dication and the inorganic chain contributes to the crystal packing. Differential scanning calorimetry measurements did not show the presence of any structural phase transitions. The structures are compared with those of (H2pipz)[Cd2Cl6(H2O)2] (3), (H2mepipz)[Cd2Cl6(H2O)2]·H2O (4) and (H2mepipz)[Cd2Cl6] (5) (L = pipz = piperazine, L′ = mepipz = N-ethylpiperazine).

Trans-2-styrylbenzothiazole complexes with mercury(II) halides. Synthesis, characterization and X-ray crystal structure of diiodobis(trans-2-styrylbenzothiazole)mercury(II)

Abstract The synthesis of trans-2-styrylbenzothiazole (L) and of its complexes with mercury(II) halides is reported. Complexes with the formulae [Hg2(L)Cl4], [Hg(L)Br2], [Hg(L)2I2] and [Hg(L)I2] were isolated and characterized by conventional chemical analysis, electronic and IR spectra and by thermal analysis. For one of these complexes, [Hg(L)2I2], the X-ray crystal structure was also determined. The complex consists of discrete [Hg(L)2I2] units in which mercury, located on a two-fold axis, shows a distorted tetrahedral coordination and the ligand molecules are bonded via nitrogen atoms with HI = 2.61(2) A and HgN = 2.36(1) A bond distances.