Tetrahedral Stereochemistry Research Articles

Structural, spectroscopic and electrochemical consequences of displacing the co-ordinated thioethers from a copper(I) N2S2 complex

The effect of detaching the two co-ordinated thioethers from the copper(I) N2S2 complex N,N′-bis{[2-(phenylmethylthio)phenyl]methylene}ethane-1,2-diaminecopper(I) perchlorate, [CuL]ClO4, has been investigated. This has been achieved by treating this complex with a second mole of the same ligand such that CuI becomes co-ordinated to two ligands, each by way of its diimine moiety. The resulting orange coloured complex, [CuL2]ClO4, is air-stable in the solid state. Results from X-ray crystal structure analysis indicate that the cation has approximately tetrahedral stereochemistry with a CuN2–CuN2 dihedral angle of 90.7(4)°, Cu–N bond lengths all 2.05(1)A and intrachelate N–Cu–N angles of 83.9(4) and 85.0(4)°. Results from cyclic voltammetry indicate quasi-reversibility of the CuI↔ CuII electron-transfer process, and a standard reduction potential of 0.23 ± 0.02 V vs. saturated calomel electrode. Chemical decomposition of the copper(II) species is also apparent, which is consistent with its high reactivity when direct synthesis was attempted.

Organolanthanoids. XVII. The Synthesis of Bis(diphenylphosphinocyclopentadienyl)ytterbium(II) and Derived Heterobimetallic Complexes [Yb(thf)n(C5H4PPh2)2Z] [Z=Ni(CO)2, Mo(CO)4 or PtMe2; n = 1 or 2; thf = Tetrahydrofuran]. The X-Ray Crystal-Structure of [Yb(thf)2(C5H4PPh2)2Ni(CO)2

Reaction of diphenylphosphinocyclopentadiene with Yb (C6F5)2 or with ytterbium metal and Hg(C6F5)2 in tetrahydrofuran ( thf ) gives, after workup with toluene, the phosphinoytter-bocene , [Yb (C5H4PPh2)2( thf )]. Treatment with thf or with N,N,N′,N′- tetramethylethane-1,2-diamine ( tmen ) yields [ Yb (C5H4PPh2)2L2] (L = thf or L2 = tmen ). Redox trans- metallation between ytterbium metal and Tl (C5H4PPh2) in l,2-dimethoxyethane ( dme ) gives thallium metal and [ Yb (C5H4PPh2)2(dme )]. The ytterbium-transition metal hetero-bimetallics [ Yb ( thf ) (C2H4PPh2)2Z]. nPhMe [Z = Ni(CO)2, Mo(CO)4 or PtMe2, n = 2/3 or 1] have been prepared by reaction of [ Yb ( thf )(C5H4PPh2)2] with Ni(CO)2(PPh3)2, Mo(CO)4( nbd ) ( nbd = norbornadiene ) or PtMe2(cod) (cod = cycloocta-1,5-diene) in toluene. Treatment of the heterobimetallics with tetrahydrofuran [Z = PtMe2 or Mo(CO)4] or a preparation in thf /toluene [Z = Ni(CO)2] yields [ Yb ( thf )2(C5H4PPh2)2PtMe2]. thf, [ Yb ( thf )2(C2H4PPh2)2Mo(CO)4]. thf and [ Yb ( thf )2 (C5H4PPh2)2Ni(CO)2]. The X-ray crystal structure of the last compound (triclinic, space group Pi, a 14.514(5), b 13.565(1), c 10.866(5) 93.11(2), β 104.65(3), γ 97.25(2)�, U 2045 � 3 , Z 2, 5141 data refined to R 0.031) reveals eight-coordinate ytterbium with a pseudo-tetrahedral arrangement of two thf ligands and the cyclopentadienyl ring centroids of two ή5 -diphenylphosphinocyclopentadienide ligands . The latter are also bonded through phosphorus to the Ni(CO)2 group, resulting in tetrahedral stereochemistry for nickel. Infrared spectroscopy suggests the presence of ytterbium- isocarbonyl bonding in solid [ Yb ( thf )(C2H4PPh2)2Z] [Z = Ni(CO)2 or Mo(CO)4].

Spectral, Magnetic and Thermal Studies on Halocobaltates(II) of the 2-Thio-dimethylpyrimidinium Cation

Abstract Some halocobaltate(II) complexes of the 2-thio-4, 6-dimethyl-pyrimidinium cation were prepared and characterized by elemental and thermal analyses, molar conductivity, magnetic measurements and electronic and i. r. spectroscopy. The visible solid state spectra and magnetic moments show that the cobalt(II) has a tetrahedral stereochemistry in all the compounds. On the basis of the thermc-gravimetric (TG, DTG) results the probable decomposition sequences of thermal dissociation of the complexes in nitrogen atmosphere are proposed.

Synthetic and spectroscopic investigations of some dioxouranium(VI) complexes of multidentate disalicylaldehyde adipoyldihydrazone

Reactions of disalicylaldehyde adipoyldihydrazone with uranyl acetate dihydrate and uranyl nitrate hexahydrate in aqueous and ethanolic media under different experimental conditions were studied and the resulting complexes with the compositions [UO 2(H 2L 2)(H 2O)] n ,[UO 2(H 2L 2)]in n,3 nH 2O, [UO 2(H 3L 2)(CH 3COO)] n 3 nH 2O, [UO 2Zn(L 2) (H 2O) 2] n 2 nH 2O, [(UO 2) 2(H 2L 2)(C 2O 4)] n 2 nH 2O and [(UO 2) 2(L 2)(py) 2(H 2O) 4] were characterized on the basis of elemental analyses, EDAX and thermoanalytical data. The structural assessment of the complexes was carried out by using molar conductance, magnetic moment and ESR data and IR, electronic and 1H NMR spectroscopy. In the complexes, the ligand functions as a bridging monobasic tetradentate, dibasic hexadentate and tetrabasic hexadentate ligand, and exhibits keto-enol tautomerism. The acetate and oxalate groups act as chelating bidentate and bridging tetradentate ligands. The complexes are considered to involve seven, eight, nine and ten coordinated uranium atoms with ligand atoms arranged in the equatorial plane around the linear uranyl group and in the heterobimetallic complex [UO 2Zn(L 2)(H 2O) 2] n 2 nH 2O the zinc atom is considered to have tetrahedral stereochemistry.

Structure of a thiolate-bridged polymeric copper(I) compound, catena-(2,9-dimethyl-1,10-phenanthroline)-μ-(thiophenolato)-copper(I)

[Cu(C6H5S)(C14H12N2)], Mr = 380.97, monoclinic, P2(1), a = 10.047 (1), b = 15.797 (2), c = 10.581 (1) A, beta = 90.78 (1) degrees, V = 1679.2 A3, Z = 4, Dm (CCl4/C5H12) = 1.50, D chi = 1.51 g cm-3, lambda(Mo K alpha) = 0.7107 A, mu = 14.2 cm-1, F(000) = 784, T = 293 (1) K, R = 0.026, wR = 0.026 for 2709 observed reflections. The title compound, [Cu(Me2-phen)(C6H5S)]n, exists as chains of [Cu(Me1phen)]+ units linked by thiophenolate S atoms. Large bridging angles at thiolate S atoms [Cu(1)--S--Cu(2)(av.) = 134 (1) degrees] preclude any Cu--Cu bonding [Cu ... Cu = 4.246 (1), 4.284 (1) A] along the chain. The CuI atoms exhibit highly distorted tetrahedral coordination, with the largest deviations from tetrahedral stereochemistry involving the N--Cu--N and S--Cu--S angles [N--Cu--N(av.) = 78.0(2), S--Cu--S(av.) = 126 (3) degrees].

Complexes of 4,5,6,7-Tetrathiocino[1,2- b:3,4- b′]diimidazolyl-1,3,8,10-tetraethyl-2,9-dithione (Et 4todit) with group IIb metal halides. Crystal and molecular structure of (Cd(II)Et 4toditCl 2) n

The capability of Et 4todit (title ligand) to coordinate through the two CS groups forced at very distant positions has been used to prepare some new ligand-bridged polymeric complexes, having stoichiometry M(II)Et 4toditX 2 (M(II) = Zn, Cd, Hg; X=Cl, Br). IR spectral results show that the ligand binds via thionic sulphur in all isolated compounds, and the low frequency spectrum of (CdEt 4toditX 2) n gives a different pattern from the rest, which all are very similar and consistent with a tetrahedral stereochemistry. The X-ray structure of (CdEt 4toditCl 2) n shows that the crystals are orthorhombic, space group P2 12 12, a=14.199(4), b=15.550(4), c= 10.575(3) Å, Z=4. Solution and refinement of the structure gave final residuals R=0.0461 and R w=0.0615 using 1402 observed reflections. Coordination around the metal is trigonal-bipyramidal. Apical sites are occupied by Cl atoms (Cl(1) and Cl(2)). Both bidentate ligand and Cl(2) are bridging to form a polymeric tridimensional structure.

Aryltelluroacetic Acids-Synthesis and Ligation with Mercury(II)

Abstract Sodium aryltellurolates (ArTe−Na +, where Ar = C6H5, 4-MeOC6H4 or 4-EtOC6H4) react with chloro-acetic acid resulting in aryltelluroacetic acids or aryl carboxymethyl tellurides (ArTeCH2 COOOH, 1) which have been characterized by molecular weight measurements, elemental analyses, IR, 1H and 13C NMR spectra. Mercury(II) chloride forms with I a complex HgCl(OOCCH2TeAr), in which the (Te,0) ligand has been demonstrated to behave as an uninegative bidentate donor by IR, 1H and 13C NMR spectra. Presuming tetrahedral stereochemistry for mercury(II), a dimeric formulation having two bridging chloro groups seems to be most plausible. The bridges, however appear to be weak in DMSO.

Synthesis of nickel(II), copper(II), zinc(II), and cadmium(II) complexes of 2-[(2-mercaptophenyl)iminomethyl] pyrrole and 2-[(2-mercaptoethyl)-iminomethyl]pyrrole by the electrochemical cleavage of a disulphide bond: the crystal structure of bis{2-[(pyrrol-2-yl)methyleneamino]thiophenolato-S,N}zinc(II)

The electrochemical oxidation of anodic metal (nickel, copper, zinc, or cadmium) in acetonitrile solutions of the Schiff bases derived from 2-pyrrolecarbaldehyde and bis(2-aminophenyl)disulphide (H2L2) or cysteamine (H2L2′) gives compounds [ML], [ML′] or [Zn(HL)2]. The crystal structure of bis{2-[(pyrrol-2-yl)methyleneamino]thiophenolato}zinc(II) is orthorhombic, space group Pbca with a= 13.764(3), b= 17.819(1), c= 16.593(2)A, and Z= 8. The zinc atom has ZnS2N2 distorted tetrahedral stereochemistry and the pyrrolic nitrogen atoms are not co-ordinated.

Polymetallic complexes: Part XI, cobalt(II), nickel(II), copper(II), manganese(II), zinc(II), cadmium(II) and mercury(II) complexes with ON?NO tetradentate Schiff base,N,N'-bis(benzoin) benzidine

The ON−NO donor Schiff base,N,N'-bis(benzoin)benzidine forms mono-, di- and tetra-nuclear complexes with metal cations. The cobalt(II) complex is a blue monomei of tetrahedral configuration. The nickel(II) and manganese(II) complexes are dimers and octahedral. A tetranuclear square planar chloro-bridged structure is proposed for the copper(II) complex. A dimeric pentacoordinated square pyramidal configuration is assigned to zinc(II) and a dinuclear tetrahedral stereochemistry is suggested for the cadmium(II) and mercury(II) complexes on the basis of analytical, conductance, magnetic susceptibility, molecular weight, i.r., electronic, d.t.g. and d.t.a. data.

Copper(II) complexes of the 14-membered cis-N2S2 macrocycle 14,14,16-trimethyl-2,6-dithia-13,17-diazatricyclo[16.4.0.07,12]docosa-1(18),7(12),8,10,16,19,21-heptaene

The ligand 14,14,16-trimethyl-2,6-dithia-13,17-diazatricyclo[16.4.0.07,12]docosa-1(18),7(12),8,10,16,19,21-heptaene (L) has been prepared by hydrolysis of the nickel(II) complex [NiLBr2]. A variety of copper(II) complexes CuL(ClO4)2, CuLBr2, CuLCl2, CuL(NO3)2·H2O, and CuL(O2CMe)2 have been characterised and their spectroscopic properties studied. The complexes do not display a reversible CuII–CuI couple in acetonitrile solution, presumably as a result of the rigid nature of the macrocycle which does not readily adapt to the preferred tetrahedral stereochemistry of copper(I).

ChemInform Abstract: [Cu(Ph2PCH2CH2PEt2)2]Cl : A Chelated Copper(I) Complex with Tetrahedral Stereochemistry.

AbstractThe air‐stable, water‐soluble title Complex (I) has been prepared by reaction of the diphosphine in CHCl3 with solid CuCl.

Some Tetrahedral Coordination Polymers of Zinc(II), Cadmium(II), and Mercury(II) Involving 4-Aminomethylpyridine

Abstract Analytical data and infrared spectral measurements down to 200 cm−1 on the 1:1 compounds formed by the interaction of zinc(II) and cadmium(II) thiocyanates and mercury(II) chloride and bromide with 4-aminomethylpyridine indicate that the compounds are coordination polymers having tetrahedral stereochemistry with bidentate bridging 4-aminomethylpyridine molecules and terminally bonded halogen/pseudohalogen groups in the solid state.

Bis((diphenylphosphino)(diethylphosphino)ethane)copper(1+) chloride: a chelated copper(I) complex with tetrahedral stereochemistry. Rate of inversion compared with those of isostructural silver(I) and gold(I) complexes

Bis((diphenylphosphino)(diethylphosphino)ethane)copper(1+) chloride: a chelated copper(I) complex with tetrahedral stereochemistry. Rate of inversion compared with those of isostructural silver(I) and gold(I) complexes

Spectroscopic studies of heteroligand complexes containing oxygen, nitrogen and sulphur donor atoms

The heteroligand complexes Ni(dtc)(xan), Ni(dtc)(salox), Ni(dtc)(dmg), Ni(xan)(dmg), Ni(xan)(salox), Ni(dmg)(salox) and Ni(salox)(sph) (where dtc − = piperidine dithiocarbamate, xan − = ethylxanthate, dmg − = dimethylglyoximate, salox − = salicylaldoximate and sph − = salicylaldehyde phenylhydrazonate) have been synthesized. Molar conductances suggest that the complexes are non-electrolytes. Magnetic and electronic spectral studies suggest square-planar geometry for all the complexes except Ni(salox)(sph) which has been shown to possess tetrahedral stereochemistry. The splitting of energy levels with respect to coordinated atoms has been found to be dependent on their nature. Infrared spectra indicate the uninegative bidentate behaviour of the ligands.

Synthesis and Characterization of 2-Thenoylhydrazine Complexes with some Bivalent Metal Ions

Abstract The 2-thenoylhydrazine, TH(L) (Fig. 1) complexes having 1:1, 1:2 or 1:3 metal-ligand stoichiometry have been prepared and characterized by elemental analyses, molar conductance, molecular weight, magnetic susceptibility, electronic, infrared, NMR, Mossbauer and X-ray powder diffraction studies. Tetrahedral stereochemistry around Zn(II), Cd(II) and Hg(II), square pyramidal geometry around VO(IV) and octahedral coordination around Mn(II), Fe(II), Co(II), Ni(II) and Cu(II) ions have been proposed in these complexes on the basis of magnetic and spectral studies.

Complexes of theophylline with divalent metal ions

Theophylline (Tp)metal ion complexes of the type M(Tp) 2(L) 2·XH 2O, where M = Cu(II), Zn(II), and Cd(II), L = O, NH 3, Cl, Br, and X = 0, 1, 2 were examined in the IR 600–200 cm −1 region. Room temperature magnetic susceptibilities were acquired for the Cu(II) complexes. These values were slightly low, and when IR spectra of the above complexes were compared to similar compounds of known structure, the metal atoms in the above complexes appear to have distorted tetrahedral stereochemistries, with theophylline acting as a bridge for polymer formation. CuTp 2 exhibits a very low magnetic susceptibility, suggesting that extensive magnetic exchange interactions have occurred.

Copper, Thioamide Complexes. Syntheses and Structures of Di-m-chloro-bis[N-(pyridin-2-yl)benzenecarbothioamide-S,N']dicopper(I) and of Bis[N-(pyridin-2-yl)benzenecarbothioamide-S,N']copper(I) Chloride, Complxes Containing Tetrahedrally Coordinated Copper Centres

The mononuclear copper(I) complex Cu(PhCSNHC5H4N)2Cl (Cu( pbctaH )2Cl) and the binuclear copper(I) complex [Cu(PhCSNHC5H4N) Cl ]2 ([Cu( pbctaH ) Cl ]2) have been prepared from copper(II) chloride and N-(pyridin-2- yl ) benzenecarbothioamide ( pbctaH ) and their structures detertnined by single-crystal X-ray diffraction studies. Cu(PhCSNHC5H4)2Cl crystallizes in the space group C2/c with the parameters a 28.042(3) Ǻ, b 6.385(a) Ǻ, c 14.158(12) Ǻ, β 117.01(1)°. The stereochemistry about the copper is essentially tetrahedral, with coordination occurring through the pyridine nitrogen and the sulfur of the thioamide group, and an NCuS angle of 95.7(1)°. [Cu(PhCSNHC5H4N)2Cl]2 crystallizes in the space group C2/c with the parameters a 16.538(6) Ǻ, b 9.135(4) Ǻ, c 16.470(6) Ǻ, β 93.925(15)°. The crystal is made up of binuclear chloro -bridged units, the essentially tetrahedral stereochemistry about the copper atoms being completed by coordination from the pyridine nitrogen and the sulfur of the thioamide group, with an NCuS angle of 99.5(1)°. The Cu2Cl2 group is non-planar, with the copper atoms 0.133 Ǻ above and the chlorine atoms 0.133 Ǻ below the average plane. Other complexes can be isolated from reactions of excess copper(II) chloride with ligand although their structures have not been characterized. A diamagnetic orange compound and a paramagnetic yellow compound apparently derived from copper(n) oxidation of the thioamide were also obtained. Other products, prepared under more basic conditions, are also described. No stable copper(II) complexes of the parent thioamide could be isolated. Use of a 4-nitro substituted benzenecarbothioamide ligand did, however, produce a bis-chelated copper(II) complex.

Complexes of 1,8-bis(2-pyridyl)-3,6-dithiaoctane with cobalt(II) halides

Several cobalt(II) halide complexes derived from 1,8-bis(2-pyridyl)-3,6-dithiaoctane (bpdto) are described. Chemical analysis suggests their formulae to be: Co(bpdto)X2 (X=Cl−, Br−, or I−). Electrolytic conductivities in acetonitrile, magnetic moments at different temperatures, solid state i.r. and u.v.-visible spectra support a tetrahedral stereochemistry around the cobalt(II). The ligand is bidentate andN-bonded in all cases.

Metal complexes of hybrid oxygen-arsenic ligands Part II: Complexes ofo-dialkyl/arylarsinobenzoic acids with cobalt(II) and nickel(II)

Reactions of hybrid oxygen-arsenic ligandso-R2As-C6H4CO2H (R=Et, C6H11 andp-tolyl) (2 mols) with M(OAc)2 · 4H2O (M=Co or Ni) (1 mol) yield Co(o-R2As-C6H4CO2)2 (R=Et orp-tolyl) and Ni(o-R2AsC6H4CO2)2 · nH2O (R=Et, n=0.5; R=C6H11, n=2) complexes. The electronic spectra and magnetic susceptibilities at different temperatures are compatible with tetrahedral and octahedral stereochemistries for cobalt(II) and nickel(II) complexes respectively. The ligand field parameters (10 Dq and B) have also been calculated and interpreted in terms of metal-ligand bond types.

Complexes of substituted benzothiazoles 4. Nickel(II) complexes of the bidentate benzothiazoles 1,2-bis(2-benzothiazolyl)benzene and 1,2-bis(2-benzothiazolyl)ethane

The nickel coordination chemistry of two potentially bidentate bis-benzothiazole ligands is compared. 1,2-Bis(2-benzothiazolyl)-benzene (OBT), which has an o-phenylene bridge, forms square planar derivatives with NiX2 (X = I, ClO4, BF4), octahedral derivatives with NiX2 (X = NCS, NO3), and five-coordinate derivatives with NiX2 (X = CI, Br). 1,2-Bis(2-benzothiazolyl)ethane (BBTE), which has an ethylene bridge, forms tetrahedral derivatives with NiX2 (X = CI, Br, I) and an octahedral complex with Ni(NO3)2. Although both ligands are capable of tetrahedral coordination about a cobalt centre, the apparent preference of tetrahedral coordination with nickel complexes of BBTE seems unusual. The only difference between the two ligands lies in the bridging group between the benzothiazole rings. Structural assignments are supported by ligand field and infrared spectra, magnetic data, and an X-ray structure of the complex [Ni(BBTE)Br2], which has been shown to have a distorted tetrahedral stereochemistry.