Synthesis and characterization of some methyl complexes of palladium(II). Part 2(1)

Summary Dichloro complexes of Pd^II, [Pd(L–L)Cl₂], where L–L=1-(thiomethyl)-2-(diphenylarsino)ethane (S–As) or 1-(thiomethyl)-2-(diphenylphosphino)ethane (S–P) andtrans-[PdL₂Cl₂], where L=diphenyl(2-phenylethyl)-phosphine (PE), diphenyl(1-naphthyl)phosphine (PN) orN-methyl-2-thiophenealdimine (SN), have been prepared and characterized. The reactions of these complexes with MeLi were investigated. The dimethyl complexes [Pd(L–L)Me₂] (L–L=S–As, S–P) and [Pd(PE)Me₂] were isolated and characterized. Reaction of [Pd(L–L)Me₂] (L–L=S–As, S–P) with HCl affords the monomethyl derivatives [Pd(L–L)Me(Cl)]. In contrast to the Pt analogues, [Pd(L–L)Me₂] and [Pd(L–L)Me(Cl)] are relatively less stable than [Pt(L–L)Me₂] and [Pt(L–L)Me(Cl)].     

Mixed ligand palladium(II) complexes of oxalate and malonate with vitamin-B6 molecules: synthesis,crystal structure and kinetics

The synthesis of six mononuclear palladium complexes of general formula [Pd(ox)/(mal)L₂] and [Pd(ox)/(mal)L] (ox = oxalate, mal = malonate, both L and L are vitamin-B₆ molecules (I), L = pyridoxine, pyridoxal and L = pyridoxamine) has been achieved. The structures of these compounds were established by elemental analysis, i.r. and ¹³C-n.m.r. [Pd(oxalate)(pyridoxine)₂] was analyzed by single crystal X-ray diffraction. It exhibits square planar coordination with bond lengths 2.015 (2) Å for Pd—N and 2.010 (2) Å for Pd—O. The interaction of [Pd(ox)₂]^2– and [Pd(mal)₂]^2– with L has been followed kinetically in order to look into the nature of products and the mechanism of formation under the conditions [Pd^II-chelate] [L] and [L].     

Copper(II) halide reactions with the - NH · CS - group in heterocyclic pentaatomic rings

Summary White crystalline complexes of general formula Cu₂L₄X₂ (where X = Cl, Br and L = 1, 3-oxazolidine-2-thione, pyrrolidine-2-thione,N-methyl-1,3-imidazolidine-2-thione andN-ethyl-1,3-imidazolidine-2-thione) and CuLX (where L = 1,3-imidazolidine-2-thione) were prepared by reduction of copper(II) halides and studied by i.r. spectroscopy in the 4000–200 cm^– range. Evidence for ligand coordination to the metal through sulphur was found in each case. The(CuCI) vibration in all the chloro derivatives falls atca. 240 cm^–.     

Novel asymmetric heterobimetallic complexes of transition metals and the kinetics of oxygen binding to a cobalt(II) complex

A series of asymmetric heterobimetallic complexes of the type [LMLSn]Cl and [LMLSn]Cl₂, where L = ethylene diamine, M = Mn^II, Co^II, Ni^II and Cu^II, M = Cr^III and Fe^III and L = 1-tryptophan and 1-valine, have been synthesized and characterized by elemental analyses, u.v.–vis., i.r., e.p.r., n.m.r., cyclic voltammetry and conductivity measurements. The Co^III analogue of these complexes was characterized by two dimensional n.m.r. COSY data. The kinetics of oxygen binding with the complex [C₁₅H₂₃N₄O₂SnCo]Cl has also been studied. The kinetic data proves that Co^II of a coordinated molecule participates in the rate-determining step of the dioxygen binding process. The plots of the pseudo-first-order rate k _obs versus [O₂] are linear passing through an intercept. The electrochemical behaviour of [C₁₅H₂₃N₄O₂SnCo]²⁺ and [C₁₅H₂₃N₄O₂SnCu]⁺ was monitored by cyclic voltammetry. Comparison of the electrochemical properties of [Co^IIISn^IV]²⁺ and [Cu^IISn^IV]⁺ reveal that, in both the species, one electron transfer reaction takes place. For the [Co^IIISn^IV]²⁺ species E ⁰ = 0.272 and –1.1 V and for the [Cu^IISn^IV]⁺ species E ⁰ = 0.078 and –0.300 V values were obtained, respectively.     

Synthesis and characterisation of some complexes of manganese(II) and iron(II) picrates with heterocyclic amines

Summary Complexes of manganese(II) and iron(II) picrates with various bidentate (L) and monodentate (L) heterocyclic bases have been synthesised; their compositions have been established as [ML₃]A₂ (1), [ML₂ · 2 H₂O]A₂ (2), [ML₆]A₂ (3) and [ML4 · 2 H₂O]A₂ (4), where M = Fe^II and Mn^II, L = 2,2-bipyridyl (bipy) and 1,10-phenanthroline (phen) in (1), A = picrate anion; M = Mn^II, L = bipy and phen in (2); M = Fe^II, L = pyridine (py), 4-picoline (4-pic) and 3-picoline (3-pic) in (3); M = Mn^II, L = py, 4-pic, quinoline (quin) and 2,6-lutidine (2,6-lut) in (4) and also M = Fe^II, L = quin and 2,6-lut.     

Electronic emission and absorption spectroscopy of the rhenium complexes Re(CO)3Cl(phosphine)2

Summary The compounds Re(CO)₃Cl(L)₂,L=triphenylphosphine, tri-p-tolyphosphine, and Re(CO)₃-Cl(L),L=1,2-bis(diethylphosphinoethane) are luminescent in solution and in crystalline form when excited between 351 nm and 514 nm at temperatures ranging from 10 K to room temperature. The absorption spectra contain a weak (E 10M ^–1 cm^–1) band in the visible region of the spectrum between 400 and 500 nm. The lowest energy transition giving rise to these spectroscopic features is assigned to a d-d transition.

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Elektronenemissions- und Absorptionsspektroskopie der Rheniumkomplexe Re(CO)₃Cl(Phoshin)₂

Zusammenfassung Die Verbindungen Re(CO)₃Cl(L)₂ mitL=Triphenylphosphin, Tri-p-tolylphosphin und Re(CO)₃Cl(L)₂ mitL=1,2-Bis(diethylphosphinoethan) sind in Lösung und im kristallinen Zustand bei Anregung zwischen 351 und 514 nm im Temperaturbereich von 10 K bis Raumtemperatur lumineszent. Die Absorptionsspektren enthalten im sichtbaren Bereich zwischen 400 und 500 nm eine schwache Bande von 10M ^–1 cm^–1. Der energetisch tiefstliegende Übergang, der für dieses Verhalten verantwortlich ist, wird einem d-d-Übergang zugeordnet.

     

4,4′-Bipyridine complexes of molybdenum(II) and tungsten(II)

Treatment of [MI₂(CO)₃(NCMe)₂] with two equivalents of 4,4-bipyridine (4,4-bipy) in CH₂Cl₂ at room temperature gave the MeCN displaced products, [MI₂(CO)₃(4,4-bipy-N)₂] (1) and (2). Equimolar amounts of [MI₂(CO)₃(NCMe)₂] and L (L = PPh₃, AsPh₃ or SbPh₃) react to give [MI₂(CO)₃(NCMe)L], which when reacted in situ with 4,4-bipy yield the new complexes, [MI₂(CO)₃(4,4-bipy-N)L] (3)–(8). Reaction of equimolar quantities of [WI₂(CO)(NCMe)( ²-RC₂R)₂] (R = Me or Ph) and 4,4-bipy gave the new bis(alkyne) complexes, [WI₂(CO)(4,4-bipy-N)( ²-RC₂R)₂] (9) and (10). Treatment of [MI₂(CO)₃(NCMe)₂] with two equivalents of (9) or (10) in CH₂Cl₂ at room temperature affords the bimetallic complexes, [MI₂(CO)₃{WI₂(CO)(4,4-bipy-N,N)( ²-RC₂R)₂}₂] (11)–(14). Equimolar quantities of [MI₂(CO)₃(NCMe)(PPh₃)] (prepared in situ) and (9) or (10), react to give the 4,4-bipy-bridged complexes, [MI₂(CO)₃{WI₂(CO)(4,4-bipy-N,N)( ²-RC₂R)₂}(PPh₃)] (15)–(18). All the new complexes, (1)–(18) were characterised by elemental analysis (C, H and N), i.r. and ¹H-n.m.r. spectroscopy.     

Equilibrium constants of some protonated,nonprotonated and hydroxo complexes of uranium(VI) with xylenol orange

Summary The species, UO₂H₃L^–, UO₂H₂L^2–, UO₂HL^3–, UO₂L^4–, UO₂(OH)L^5– and UO₂(OH)₂L^6– are found in the equilibria between uranyl ions and 3,3-bis[N,N-di(carboxymethyl)-aminomethyl]-o-cresolsulphonphthalein (H₆L; xylenol orange; dcac) in aqueous solution. The equilibria have been studied by the potentiometric method at 25° and at an ionic strength of 0.1M (KNO₃). New algebraic equations have been employed to evaluate the equilibrium constants.     

The preparation and characterization of acetylacetonato-bis(η-methylcyclopentadienyl)titanium(IV) complexes

Summary A series of [L₂TiL]⁺X^–compounds where L is the conjugate base of acetylacetone, L=-MeC₅H₄ and X^–= ClO ₄ ^– , BF ₄ ^– , FeCl ₄ ^– , ZnCl₃(H₂O)^–, SnCl ₃ ^– , CdCl ₄ ^2– , HgCl ₄ ^2– , Br^– or I^–, have been prepared by adding X^– to the aqueous solution of [L₂TiL]⁺Cl^–. Conductivity measurements in nitrobenzene for all compounds indicate that these complexes are electrolytes. The i.r. frequencies for various vibrational modes have been assigned. The ligand L appears to be chelating and the titanium atom is essentially tetracoordinate. The bonding in these complexes is discussed.On study leave from S. D. College, Muzaffar Nagar, U.P., India.     

Equilibria in complexes ofn-heterocyclic molecules,part XXVI. Reactions of hydroxide and water with the tris-(2,2′-bipyrazine)iron(II) and tris-[2,2′-bis-(5,6-dihydro-4-H-1,3-oxazine)]iron(II) ions

Summary The reactions of [Fe(bipyz)₃]²⁺ (bipyz = 2,2-bipyrazine) and [Fe(box)₃]²⁺ [box = 2,2-bis-(5,6-dihydro-4-H-1,3-oxazine] with H₂O and HO^– in aqueous solution have been followed. The [Fe(bipyz)₃]²⁺ ion is attacked at the ligand with both nucleophiles and the ligand is cleaved. A similar reaction between HO^– and [Fe(box)₃]²⁺ is observed. Detailed kinetics for all reactions are reported.phen 1,10-phenanthroline - bipy 2,2-bipyridyl - bipym 2,2-bipyrimidine Part XXV: R. D. Gillard, W. S. Walters and P. A. Williams,J. Chem. Soc. Dalton Trans., in press.     

Complexes of dioxouranium(VI) with zwitter-ionic forms of Bi- and tetra-dentateSchiff bases

Potentially bi- and tetra-dentateSchiff bases derived from salicylaldehyde react with hydrated uranyl salts to give complexes: UO₂H₂ LX ₂, UO₂H₂ LX ₂ and UO₂(HL)₂ X ₂ [H₂ L=N,N-propane-1,3-diylbis(salicylideneimine), H₂ L=N,N-ethylenebis(salicylideneimine) and HL=N-phenylsalicylideneimine;X ^–=Cl^–, Br^–, I^–, NO₃ ^–, ClO₄ ^–, and NCS^–]. Because of marked spectral similrities with the structurally known Ca(H₂ L) (NO₃)₂, theSchiff bases are coordinated through the negatively charged phenolic oxygen atoms and not the nitrogen atoms of the azomethine groups which carry the protons transferred from phenolic groups on coordination. Halide, nitrate, perchlorate and thiocyanate groups are covalently bonded to the uranyl ion, resulting a 6-coordinated uranium ion in the halo and thiocyanato complexes and 8-coordinated in nitrato and perchlorato complexes.

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Komplexe von Dioxouranyl(VI) mit zwitterionischen Formen von zwei- und vierzähnigen Schiff-Basen

Zusammenfassung Von Salizylaldehyd abgeleitete zwei- und vierzähnigeSchiff-Basen reagieren mit hydratisierten Uranylsalzen zu Komplexen folgenden Typs: UO₂H₂ LX ₂, UO₂H₂ LX ₂ und UO₂(HL)₂ X ₂ [H₂ L=N,N-Propan-1,3-diylbis(salicylidenimin), H₂ L=N,N-Ethylen-bis(salicylidenimin) und HL=N-Phenylsalicylidenimin;X ^–=Cl^–, Br^–, I^–, NO₃ ^–, ClO₄ ^– und NCS^–]. Auf Grund eindeutiger spektraler Ähnlichkeiten mit dem bekannten Ca(H₂ L) (NO₃)₂ wird auf Koordination über die negativ geladenen phenolischen Sauerstoffatome (und nicht über die Azomethin-Stickstoffe) geschlossen. Die AnionenX ^– sind kovalent an das Uranyl-Ion gebunden; damit ergibt sich ein hexakoordiniertes Uranyl-Ion für die Halogen- und Thiocyanat-Komplexe und Oktakoordination für die Nitrat- und Perchlorat-Komplexe.

     

Synthesis and characterization of cobalt(II), nickel(II), copper(II) and zinc(II) complexes with acetylacetone bis-benzoylhydrazone and acetylacetone bis-isonicotinoylhydrazone

Summary Acetylacetone bis-benzoylhydrazone (PhCONHN=CMe)₂ CH₂(LH₂) and acetylacetone bis-isonicotinoylhydrazone (NC₅H₄CONHN=CMe)₂CH₂(LH₂) complexes of the types [ML] and [ML] (M = Co^II, Ni^II, Cu^II or Zn^II) have been prepared and characterized. All the complexes are non-electrolytes and the cobalt(II) complexes are lowspin, the nickel(II) complexes are diamagnetic and the copper(II) complexes are paramagnetic. The ligands chelate via two C=N groups and two deprotonated enolate groups. The e.s.r. spectra of the copper(II) complexes indicate a tetragonally distorted dimeric structure. The X-ray diffraction parameters for [CoL] and [NiL] correspond to a tetragonal crystal lattice.     

Synthesis and magnetic properties of trinuclear copper(II) complexes bridged by dimethylglyoximate groups

Summary New three Cu^II-Cu^II-Cu^II homotrinuclear complexes have been synthesized, namely [Cu(dmg)₂{CuL}₂](ClO₄)₂ [L = 5-nitro-1,10-phenanthroline (5-NO₂-phen), 4,4-dimethyl-2,2-bipyridiine (DMbpy), tetramethylenediamine (TMDA) and dimethylglyoximate ion (dmg)^2-]. The magnetic susceptibilities of complexes (1) (L = 5-NO₂-phen) and (2) (L = DMbpy) were measured in the 4.2–300 K range, giving the parameters,J = -335cm^-1 (1) andJ= -327.5cm^-1 (2). The results demonstrate a very strong antiferromagnetic exchange interaction between the adjacent copper(II) ions.     

Xanthate complexes of nickel with nitrogen donor ligands. Part V

Nickel(II) xanthate complexes of general formula, [Ni(Rxa)₂(L)] [R = i-Pr, i-Am, xa = OCS^– ₂, L = 4,7-diphenyl-1,10-phenanthroline(baphen), 4,4-dimethyl-2,2-bipyridyl (me₂bpy), 2-9-dimethyl-1,10-phenanthroline(neo) or trans-1,2-diaminocyclohexane (dch)] and [Ni(Rxa)(cyclam)](Rxa) (= 1,4,8,11-tetraazacyclotetradecane) have been synthesized and characterized by elemental analyses, i.r. and electronic spectroscopy, magnetic and conductivity measurements. The complexes with cyclam were studied by cyclic voltammetry. Values of magnetic moments at room temperature lie within the 3.25–3.51 B.M. range and thus indicate the presence of two unpaired electrons, except for the complexes with cyclam, where the anomalous values of 1.76 and 1.74 B.M. were obtained in respect to the nickel(II) complexes. Magnetic susceptibility data for [Ni(i-Prxa)(cyclam)](i-Prxa) were measured over the 79–298 K range and indicate no exchange interaction between paramagnetic nickel(II) centres.     

O-phenylenebis(oxamato) bridged trinuclear copper(II) complexes: synthesis and magnetic properties

Summary Four new trinuclear copper(II) complexes bridged by o-phenylenebis(oxamato) (opba) and end-capped with 1,10-phenanthroline (phen), 5-nitro-1,10-phenanthroline (NO₂-phen), 2,2-bipyridyl (bipy) or 4,4-dimethyl-2,2-bipyridyl (Me₂bipy), {[Cu(opba)][Cu(L)]₂}(ClO₄)₂ (L = phen, NO₂-phen, bipy or Me₂bipy), have been synthesized and characterized. Based on i.r., elemental analyses, conductivity measurements and electronic spectra, oxamato-bridged structures consisting of three copper(II) ions in which each copper(II) ion has a square-planar environment are proposed. The temperature-dependent magnetic susceptibility of {[Cu(opba)][Cu(phen)]₂} (ClO₄)₂ has been studied in the 4.2–300 K range, giving the exchange integral J = -134.4cm^–1. The result revealed the operation of an antiferromagnetic spin-exchange interaction between the adjacent copper ions.     

Rhodium(1) carbonyl complexes with alkyl sulphoxides and sulphides

Summary Rhodium(I) carbonyl complexes, namely Rh(CO)X(R₂SO)₂ (R = Me, n-Pr or n-Bu) and Rh(CO)X(R₂S)₂ (R = Me, Et or i-Pr) and X = CI or Br, have been prepared and characterized. The compounds Rh(CO)X[P(OPh)₃]₂ X = Cl or Br, have also been isolated. In the R₂SO and R₂S complexes, the carbonyl stretching frequencies occur atca. 2020–2025 cm^–1 andca. 1950–1980 cm^–1 respectively. In the R₂SO ligand containing complexes v(S-O) occurs atca. 1100–1125 cm^–1 indicative of metal-sulphur coordination. In presence of HBF₄, the addition of an excess of Me₂SO to (OC)₂Rh(-Cl)₂Rh(CO)₂ gives [Rh(Me₂SO)₆]³⁺ in which the central metal atom undergoes spontaneous oxidation from Rh¹(d⁸) to Rh^III(d⁶). The complexes have been characterized additionally by u.v.vis. spectra, conductivity measurements and by elemental analyses.     

Mixed metal complexes in solution. Part 4. Formation and stability of heterobinuclear complexes of cadmium(II)-citrate with some bivalent metal ions in aqueous solution

Summary The systems, Cd-Ni-citrate, Cd-Mn-citrate and Cd-Zn citrate have been investigated pH-metrically at 25°C and I = 0.1 mol dm^–3 (KNO₃).As previously found for analogous citrate systems (namely for Cu-Ni-, Cu-Zn- and Ni-Zn-citrate) the existence of mixed metal complexes of the type [MM(cit)₂H_–2]^4– has been shown. In addition, the species [MM(cit)₂H_–1]^3– was also found to be present for Cd-Ni- and Cd-Zn-citrate systems The significance of the formation of such species is discussed.The existence of mixed metal complexes is also discussed in connection with the transport and the absorption of metal ions in biological systems.     

Synthesis and magnetism of tetrachlorophthalato-bridged manganese(II) binuclear complexes

Summary Four novel manganese(II) binuclear complexes have been prepared and characterized, namely [Mn₂(TCPHTA)(L)₄]-(ClO₄)₂ [where L is 2,2-bipyridyl (bipy), 1,10-phenanthroline (phen), 4,4-dimethyl-2,2-bipyridyl (Me₂bipy) or 5-nitro-1,10-phenanthroline (NO₂-phen) and TCPHTA is the tetrachlorophthalate dianion]. Based on i.r. spectra, elemental analyses, conductivity measurements, extended tetrachlorophthalato-bridged structures consisting of two manganese(II) ions in which each manganese(II) ion has a distorted octahedral environment are proposed for these structures. The temperature dependence of the magnetic susceptibility for [Mn₂(TCPHTA)(phen)₄]-(ClO₄)₂·H₂O was measured over the 4–300 K range and the observed data were successfully simulated by an equation based on the spin Hamiltonian operator ( = –2J ₁· ₂), giving the exchange integralJ = –1.05 cm^–1. This result is indication of a weak antiferromagnetic spin exchange interaction between the metal ions.     

Seven-coordinate complexes of molybdenum(II) and tungsten(II). Preparation and spectral properties of [MI2(CO)3LL′] {M=Mo or W; L=PPh3, AsPh3 or SbPh3; L′=SC(NH2)2, SC(NMe2)2 or SC(NH2)Me}

Summary The seven-coordinate complexes [MI₂(CO)₃(NCMe)₂] (M=Mo or W) react either in acetone or methanol with one equivalent of L (L=PPh₃, AsPh₃ or SbPh₃) to give [MI₂(CO)₃(NCMe)L], which when reactedin situ with one equivalent of L {L=SC(NH₂)₂, SC(NMe₂)₂ or SC(NH₂)Me} affords good yields of the new mixed complexes [MI₂(CO)₃LL]via successive displacement of acetonitrile ligands.     

A convenient synthesis of 1, 1′-dithiolatoferrocene and the preparation of [ReO{Fe(C5H4S)2}2]−

Summary LiAlH₄ reduction of 1, 1-ferrocene-bis(dimethyldithiocarbamates) gives 1, 1-dithiolatoferrocene [Fc(SH)₂] in high yield. The dithiol reacts with first-row transition metals to give polymeric products but with [ReOCl₃–(PPh₃)₂] the complex [ReO(FcS₂)₂]^–, can be isolated as a tetraphenylphosphonium salt in good yield.