Showing papers in "Journal of The Chemical Society-dalton Transactions in 1976"
TL;DR: In this paper, a study of the core-electron X-ray photoelectron (X-p) spectra of the f0 compounds La2O3, LaMO3(M = Fe and Co), CeO2, and BaCeO3 is described.
Abstract: A study of the core-electron X-ray photoelectron (X-p.e.) spectra of the f0 compounds La2O3, LaMO3(M = Fe and Co), CeO2, and BaCeO3 is described. Results on the chelate species [La(tmhd)3] and [Ce(tmhd)4](tmhd = 2,2,6,6-tetramethylheptane-3,5-dionato) are included for comparison. Special precautions have been taken to ensure an optimal degree of surface purity of the samples. Satellite structure has been observed for the 4p, in addition to the 3d and 4d, signals in both the lanthanum(III) and cerium(IV) compounds. These satellites arc discussed in terms of coexcitations of the charge-transfer type, principally O 2p→ metal 4f transitions. In the cerium(IV) oxides the satellites are apparently due to energy-gain (representing ‘ shake-down ’) rather than energy-loss (shake-up) processes.
841 citations
TL;DR: In this paper, the bulky diphosphine 1,3-[(di-t-butylphosphino)methyl]benzene undergoes metallation very readily to give a new type of tridentate chelating system, 2,6-bis[(diphosphino),methyl]phenyl (pcp), and complexes of the types [MX(pcp)](M = Ni, Pd, or Pt; X = Cl, Br, H, C⋮CPh, or CN; M = Rh,
Abstract: The bulky diphosphine 1,3-[(di-t-butylphosphino)methyl]benzene undergoes metallation very readily to give a new type of tridentate chelating system, 2,6-bis[(di-t-butylphosphino)methyl]phenyl (pcp). Complexes prepared are of the types [MX(pcp)](M = Ni, Pd, or Pt; X = Cl, Br, H, C⋮CPh, or CN; M = Rh, X = CO), [MHCl(pcp)](M = Rh or Ir), and [IrHCl(CO)(pcp)]. [Ni(CO)(pcp)][BPh4] was also prepared. 1H- and 31P- n.m.r. data and i.r. data are given.
620 citations
TL;DR: In this paper, two methods were described for the synthesis of the unusual bivalent Group 4B metal alkyls M[CH(SiMe3)2]2(M = Ge, Sn, or Pb) from Li[CH[SiMe 3]2] indiethyl ether at 0 to 20°C.
Abstract: Two methods are described for the synthesis of the unusual bivalent Group 4B metal alkyls M[CH(SiMe3)2]2(M = Ge, Sn,or Pb)from Li[CH(SiMe3)2] indiethyl ether at 0 to –20°C and (a) the metal(II) chloride (M = Sn or Pb) or (b) M[N(SiMe3)2]2(M = Ge or Sn). At ambient temperature in cyclohexane or benzene the solutions are yellow (Ge), red (Sn), or purple (Pb), and the compounds are monomeric and in a singlet electronic ground state. There are colour changes between the solid and the melt, and the compounds tend to become colourless at –196 °C. The crystal structure of the tin(II) alkyl shows a centrosymmetric dimer with a Sn–Sn bond (2.76 A) similar in length to that in Sn2Ph6, and the two pairs of geminal alkyl groups in a mutually trans arrangement. The solid germanium compound is inferred to be structurally similar because of the presence of a strong polarised Raman line at 300 cm–1. The monomer is believed to be angular with three approximately sp2 hybridised orbitals at the metal, one of which is non-bonding; the dimer. with a SnSn bent double bond, is formed by overlap of the non-bonding orbital of each monomer unit with the orthogonal vacant pz orbital of the other.
310 citations
TL;DR: The effect of different modes of co-ordination on the spectrum of the acetate ion is reviewed in this paper, where a series of metal acetates and acetato-complexes are reported.
Abstract: The effect of different modes of co-ordination on the i.r. spectrum of the acetate ion is reviewed. Infrared and 1H n.m.r. spectra of a series of metal acetates and acetato-complexes are reported. and the type of co-ordination identified: B2O(O2CMe)4 and Na[B2O(O2CMe)5] contain both bridging and unidentate acetate; Al(O2CMe)3 probably contains bridging acetate only: Si(O2CMe)4, Ge(O2CMe)4, K2[Si(O2CMe)6], and K2[Ge(O2CMe)5] contain only unidentate acetate: Zr(O2CMe)4 and Pb(O2CMe)4 contain only chelating acetate: K2[Sn(O2CMe)6], K2[Pb(O2CMe)6], and [NMe4][Sn(OMe)5] contain both chelating and unidentate acetate; and Sn(O2CMe)4 contains symmetrical and unsymmetrical chelating acetate.
184 citations
TL;DR: In this paper, the electronic factors responsible for the breakdown of the Polyhedral Skeletal Electron Pair rules when applied to the gold clusters are discussed, and the ligands to these bare metal clusters encourage a more favorable hybridisation of the metal orbitals and results in stronger radial metal-metal bonding.
Abstract: Molecular-orbital calculations on [Au6]2+ and [Aug9]3+ clusters have shown that the overlap of the gold 6s orbitals makes a dominant contribution to the bonding. Co-ordination of ligands to these ‘ bare ’ metal clusters encourages a more favourable hybridisation of the metal orbitals and results in stronger radial metal–metal bonding. The electronic factors responsible for the breakdown of the Polyhedral Skeletal Electron Pair rules when applied to the gold clusters are discussed.
121 citations
TL;DR: The ditertiary phosphines Ph2P[CH2]nPPh2(n= 2 or 3, dppe and dppp respectively) displace cyclo-octa-1,5-diene (cod) from [PtMe(cod)Cl] to give monomeric complexes as discussed by the authors.
Abstract: The ditertiary phosphines Ph2P[CH2]nPPh2(n= 2 or 3, dppe and dppp respectively) displace cyclo-octa- 1,5-diene (cod) from [PtMe(cod)Cl] to give monomeric complexes [PtMe(Cl)(dppe)] and [PtMe(Cl)(dppp)]. A similar reaction using Ph2PCH2PPh2(dppm) gives predominantly an oligomer [{PtMe(Cl)(dppm)}n] containing bridging dppm groups, together with a small amount of monomeric [PtMe(Cl)(dppm)]. Molecular-weight measurements suggest that the oligomers [{PtMe(X)(dppm)}n](X = Cl or I) may be trimeric in solution (n= 3). Dimethyl complexes, [PtMe2(diphosphine)], have been obtained from [PtMe2(cod)] and dppe, dppp, or dppm, 31P N.m.r. parameters and oxidative-addition reaction of the complexes with iodine or methyl iodide are very dependent on the ditertiary phosphine.
108 citations
TL;DR: In this paper, the 1H n.m.r. spectra of doublets characteristic of diastereotopicallv distinct SiMe3 groups in compounds of the form SnR2(A)B (A ≠ B).
Abstract: Bis[bis(trimethylsiiyl)methyl]tin, SnR2, has an extensive chemistry, behaving as (i) a Lewis base, (ii) a Lewis acid, or (iii) undergoing oxidative addition (insertion reactions). The following complexes have been isolated, many as well characterised crystals. For class (i), these include (M = Cr or Mo)[M(CO)5(SnR2)], trans-[M(CO)4-(SnR2)2], [Fe2(η-C5H5)2(CO)3(SnR2)], [RhCl(PPh3)2(SnR2)], and [PtCl(PEt3)(SnR2)(SnR2Cl)]: for class (ii), the readily thermally-dissociable 1 : 1 adducts with pyridine, 4-methylpyridine, or piperidine, and for class (iii), SnR2(A)B (AB = HCl,HF, MeI, RCl, Cl2, Br, O2, CH2:CMeCMe:CH2, [Mo(η-C5H5)(CO)3X](X = H or Me), [Fe(η-C5H5)(CO)2X](X = Cl or Me), [{Fe(CO)4}2]. and [PtCl2(PEt3)(SnR2)]). An interesting feature is the appearance in the 1H n.m.r. spectra of doublets characteristic of diastereotopicallv distinct SiMe3 groups in compounds of the form SnR2(A)B (A ≠ B). The complex [Mo(CO)5(PbR2)] has also been obtained.
95 citations
TL;DR: The crystal structure of the copper(I) iodide pyridine adduct has been determined by X-ray diffraction at 295 K and refined by least squares to R 0.057 for 2 710 "observed" reflections as mentioned in this paper.
Abstract: The crystal structure of the copper(I) iodide pyridine adduct has been determined by X-ray diffraction at 295 K and refined by least squares to R 0.057 for 2 710 ‘observed’ reflections. Crystals are orthorhombic, space group P212121, with a= 16.032(6), b= 15.510(2), and c= 11.756(3)A. The asymmetric unit is Cu4I4py4, based on the well-known tetrahedral tetrameric Cu4I4 unit, with Cu–N 2.04, Cu–I 2.70, and Cu–Cu 2.69 A; the latter distance is much shorter than in the analogous complexes formed with phosphine and arsine ligands.
90 citations
TL;DR: In this article, the use of several tertiary-phosphine-ruthenium complexes in the catalytic hydroformylation of alkenes is described, and a mechanism involving Ru(H 2(CO)2(PPh3)3) as the principal active catalytic species is suggested.
Abstract: The use of several tertiary-phosphine–ruthenium complexes in the catalytic hydroformylation of alkenes is described. For mononuclear complexes the conversions into aldehyde, as well as the ratios of straight- to branched-chain aldehyde are essentially constant; the ruthenium complex recovered from the reactions is invariably tricarbonylbis(triphenylphosphine) ruthenium(0), Ru(CO)3(PPh3)2. The dependence of conversion and aldehyde ratios on catalyst concentration, temperature, partial and total pressures, nature of the substrate, and addition of excess of triphenylphosphine and other ligands in hydroformylation with Ru(CO)3(PPh3)2 is also described. Based on these results, a mechanism involving Ru(H)2(CO)2(PPh3) as the principal active catalytic species is suggested.The compound Ru(CO)3(PPh3)2 is also active for the hydrogenation of alkenes and aldehydes and mechanisms for these reactions are suggested.Complexes formed by addition of various ligands to dodecacarbonyltriruthenium, Ru3(CO)12, are shown to be less active for hydroformylation than mononuclear complexes.
86 citations
TL;DR: In this article, the first-order rate constant increases with increasing concentration of Na2[N2O3] in the presence of nitrite and allowing the estimation of pK1ca.
Abstract: The kinetics of decompostion of sodium trioxodinitrate. Na2[N2O3], have been measured over the range pH 1–10 at several temperatures. At pH > 4, the rate-determining step is breakdown of [HN2O3]– to [NO2]– and N2O. The pK for [HN2O3]– at I= 0.25 mol dm–3 and 25 °C is 9.35, and λmax.= 237nm. At lower pH values, the rate increases with increasing acdity with production of NO, which is the predominant product at pH2. At these pH values kobs, the measured first-order rate constant, increases with increasing concentration of Na2[N2O3]. This is attributed to a reaction with trace amounts of HNO2, giving NO and reforming [NO2]–, rather than to an enhanced instability of H2N2O3. Extrapolation of kobs. to zero [N2O32–] at pH < 3 gives kobs.* which corrsponds to decomposition via[HN2O3]–; kobs.* decreases with decreasing pH. showing that H2N2O3 is stable compared to [HN2O3]– in the absence of nitrite and allowing the estimation of pK1ca.3·0. Addition of [NO2]– to Na2[N2O3] at pH 5 results in the production of NO, the use of [15NO2]– showing that this is not attributable to the disproportionation of HNO2 and also that both molecules of NO produced in the reaction are derived from the nitrogen atoms of [N2O3]2–. The acid-catalysed HNO2-catalysed reaction at lower pH obeys the rate equation Rate ∝[H+][HNO2][H2N2O3], but the value of the third-order rate constant is too high for a diffusion-controlled electrophilic nitrosation reaction. Added ethanol at these pH values has very marked inhibitory effect on the rate, so it is suggested that formation of NO results from a free-radical chain reaction.
77 citations
TL;DR: In this article, the e.s.r. spectra of the manganese(II) species are described and assignments made, and the existence of dimethyl- and dlphenyl-manganese is questioned.
Abstract: The interaction of manganese(U) chloride with Grignard or dialkylmagnesium reagents derived from Me3CCH2Cl. Me2PhCCH2Cl, and Me3SiCH2Cl yields thermally stable dialkyl compounds of manganese(II). For the neophyl compound. Mn2(CH2CMe2Ph)π. a dimeric structure with a bridging alkyl group, the phenyl group of which lies over a manganese atom, has been confirmed by X-ray diffraction (to be reported separately). For the trimethylsilyl-methyl compound, {Mn(CH2SiMe3)2}n, tetrahedral co-ordination of MnII is achieved by polymerisation via alkyl bridges (cf. BeMe2).The dialkyl compounds interact with Lewis bases such as NNN′N′-tetramethylethylenediamine to give mono-meric complexes of the type MnR2·tmed and with lithium alkyls to give solvated dilithium tetra-alkylmanganate(II) complexes Li2[MnR4]. Salts where R = Me are also described and the existence of dimethyl- and dlphenyl-manganese is questioned.The e.s.r. spectra of the manganese(II) species are described and assignments made. Oxidation of the dialkyl compounds in the presence of an excess of alkylating agent gives green solutions whose e.s.r. spectra are similar to that of tetranorbornylmanganese(IV) so that the solutions presumably contain unstable manganese(IV) alkyls.
TL;DR: In this paper, partial quadrupole splitting (p.q.s.) parameters were calculated for a variety of ligands in trigonal-bipyramidal structures.
Abstract: Mossbauer parameters are reported for ten cationic organotin(IV) complexes of type [R3SnL2][BPh4](R = alkyl or phenyl, L = electrongegative ligand). Details are given of a regression method which is used to distinguish structural isomers of trigonal-bipyramidal [R3SnL2] species by their 119Sn quadrupole splittings. By use of new and literature data, partial quadrupole splitting (p.q.s.) parameters are calculated for a variety of ligands in trigonal-bipyramidal structures. Comparison of theory with experiment indicates that the additive model gives a consistent account of the relationship between quadrupole splitting and stereochemistry in trigonal-bipyramidal organotin(IV) compounds. The 119Sn parameters are used to calculate p.q.s. parameters for 121SbV, thus extending recent work on application of the additive model to five-co-ordinate organoantimony(V) compounds.
TL;DR: In this article, a number of iso-and hetero-polyvanadate anions are reported, including vanadium-51 n.p.m. and tetrahedral vanadium.
Abstract: Vanadium-51 n.m.r. spectra of a number of iso- and hetero-polyvanadate anions are reported. Spectra of solutions containing [V10O28]6–(pH 6.5–3.5) are consistent with the known solid-state structure of this anion. The [VO2]+ cation in aqueous solution almost certainly has an octahedral cis-dioxo-structure as its n.m.r. linewidth is comparable with those for the cis compounds [VO2(04C2)2]3– and [VO2(edta)]3–(edta = ethylenediaminetetra-acetate), which are broader than those for pseudo-tetrahedral [VCl2O2]– and [VF2O2]–. Chemical shifts of pseudo-octahedral vanadium atoms in [VxW6–xO19]n–. [PVxW12–xO40]n–. [PMo12–xVxO40]n–, and [VVxW12–xO40]n– anions range from 506 to 545 p.p.m. (VCl3O reference) and linewidthsfrom 60 to 200 Hz (2.6–9 p.p.m.). Multiple lines in the specta of the 1 : 12 (Keggin) heteropolyanions confirm the existence of geometrical isomers distinguished by the relative positions of two or more vanadium atoms in the polyanion structure. Phosphorus-31 n.m.r. spectra confirm that most if not all of the possible isomers of this type areformed. The chemical shifts of 31P in [PMo12040]3– and [PW12040]3– are ca. 11 and 21 p.p.m. upfield from the unprotonated [PO4]3– ion (–6 with respect to 85% H,PO,). Introduction of V atoms in the heteropoly structures causes a progressive decrease in the chemical shift, enabling mixtures of such Keggin anions to be analyzed by n.m.r. A parallel variation in 51V chemical shift is found for [VO4]3–(536) and the tetrahedral vanadium in [VV3W9040]6–(553) and [VV2W10O40]5–(556 p.p.m.).
TL;DR: In this paper, it was shown that the conformations about the P-N bonds are influenced by the stereochemical bulk of R. The dependence on the R groups has been found for the diphosphinoamines, Ph2P·NR·PPhCl (R = Me, Et, Prn, Pri, and But).
Abstract: 1 H-{31P} and 31P n.m.r. measurements on the triphosphazanes (Ph2P·NR)2PPh show that J(PNP) is +280 Hz when R = Me and 25.1 Hz when R = Et. A similar marked dependence on the R groups has been found for the diphosphinoamines, Ph2P·NR·PPhCl (R = Me, Et, Prn, Pri, and But)(+334 to –35 Hz), and this may be related to the conformations about the P–N bonds, which are influenced by the stereochemical bulk of R. 1H-{31P} INDOR experiments on the symmetrical diphosphinoamines, Ph2P·NR·PPh2(R = Me, Et, and Pri), indicatethat J(PNP) is much greater when R = Me than when R = Et or Pri.
TL;DR: The contribution of mixed-valence electron delocalisation to the ferromagnetic exchange between the iron(III) ions in Prussian Blue {FeIII4[eII(CN)6]3·14H2O} has been estimated theoretically.
Abstract: The contribution of mixed-valence electron delocalisation to the ferromagnetic exchange between the iron(III) ions in Prussian Blue {FeIII4[eII(CN)6]3·14H2O} has been estimated theoretically. Agreement between the calculated and observed values of the Curie temperature is quite good.
TL;DR: A number of solution-stable species of general formula MR3˙[R = CH(SiMe3)2: M = Ge or Sn] have been prepared and characterised by e.g. spectroscopy.
Abstract: A number of solution-stable species of general formula MR3˙[R = CH(SiMe3)2: M = Si. Ge. or Sn], M(NR′2)3˙ and M (NR′R″)3˙(R′= SiMe3, R″= CMe3, M = Ge or Sn) have been prepared and characterised by e.s.r. spectroscopy. Most of the radicals have been generated by photolysis of the bivalent Group 4 species MR, M(NR′2)2 or M(NR′R″)2 when available; others have been obtained by alternative photochemical experiments. The e.s.r. parameters indicate that the radicals have non-planar structures similar to those of analogous transient species such as MMe3˙. The mechanism of formation of the radicals is discussed : their unusual stability (e.g. SnR3˙ has a halflife of ca. 1 year at 20 °C) is attributed mainly to steric hindrance to dimerisation.
TL;DR: The crystal structures of the title compounds, [Sb(S2C·NEt2)3], (I), and [Bi(S 2C ·NEt 2)3]-II, have been determined from X-ray diffractometer data by the heavy-atom method and refined by least squares to R 0.07 (I, 3 [332 reflections] and 0.09 (II)[6 029 reflections] as mentioned in this paper.
Abstract: The crystal structures of the title compounds, [Sb(S2C·NEt2)3], (I), and [Bi(S2C·NEt2)3](II) have been determined from X-ray diffractometer data by the heavy-atom method and refined by least squares to R 0.07 (I), 3 [332 reflections] and 0.09 (II)[6 029 reflections]. Crystals of both are monoclinic, Z= 4, space group P21/a; (I): a= 14.665(5), b= 13.619(5), c= 12.642(4)A, β= 99.86(4)°; (II): a= 14.825(4), b= 13.640(2), c= 12.605(3)A, β= 100.01(3)°.(I) and (II) are isostructural; the symmetry of the M(S2C)3 unit resembles the C3 symmetry of the arsenic derivative, with three short M–S bonds fac, one from each ligand [M–S 2.487(4)–2.631(4)(I); 2.595(5)–2.775(5)A(II)], and three long bonds [M–S 2.886(4)–2.965(4)(I); 2.956(5)–2.964(4)A(II)], with a considerable gap in the co-ordination about the pseudo-C3 axis suggesting a stereochemically active lone-pair. The inversion image of the molecule approaches near this direction also, with a weak intermolecular metal–sulphur interaction [M ⋯ SI, 3.389(4)(I), 3.210(4)A(II)].
TL;DR: In this paper, a series of mononuclear methoxo-complexes were constructed by metathesis of [MR(Cl)(PPh3)2] with Na(OMe).
Abstract: A series of mononuclear methoxo-complexes. cis- and trans-[MR(OMe)(PPh3)2](M = Pd or Pt; R = aryl or alkenyl) has been prepared by metathesis of [MR(Cl)(PPh3)2] with Na(OMe). Hydrolysis of the methoxo-complexes gives corresponding hydroxo-complexes. trans-[MR(OH)(PPh3)2], which are also obtained from [MR(OCMe2)(PPh3)2]+ and [OH]–. The stability and nature of the M–OR bond (R = H or Me) are influenced markedly by the identity of the metal and the trans ligand, R. The anionic character of the OH or OR ligand increases in the orders Pt < Pd and C6F5 < CClCCl2 < CHCCl2 < Ph. The hydroxo-complexes react with PhCOMe and MeNO2 to give the corresponding condensates. trans-[PtR(CH2X)(PPh3)2](X = COPh or NO2). The condensation reaction is facilitated by the increase in anionic character of the OH ligand.
TL;DR: In this paper, the symmetry of the crystal field surrounding the lanthanoid ion has been assigned by an analysis of the Stark splittings seen in the 5D0→7FJ emission lines.
Abstract: Emission spectra have been recorded of polycrystalline samples of Na7EuIIIW10O35·xH2O and K13EuIII(SiW11O39)2·xH2O. The fluorescence of the europium ion can be efficiently pumped via the internal states of the tungstate groups. The cluster maintains its integrity in neutral aqueous solution, in which the europium ion also luminesces intensely. The symmetry of the crystal field surrounding the lanthanoid ion has been assigned by an analysis of the Stark splittings seen in the 5D0→7FJ emission lines. The praseodymium(III), neodymium(III), and holmium(III) analogues of Na7EuIIIW10O35·xH2O do not give enhanced fluorescence under excitation in the poly-tungstate bands, but emission could be detected by direct laser excitation of the f-f states. An analysis of the praseodymium spectrum has been attemmpted, but overlapping of transitions prevents an unambiguous assignment of the Stark splittings.
TL;DR: In this paper, the first vertical ionisation potential is close to that of the free metal; the metal lone-pair orbital is progressively higher in M(NR′R″), and the second band is the second one, being preceded by the antibonding b2 molecular orbital (mo) formed by the nitrogen lonepair atomic orbitals (aos).
Abstract: He(I) photoelectron (pe) spectraof (i) themonomeric, presumed-bent, compounds MR2, M(NR′2)2, and M(NR′R″)2[M = Ge, Sn, or Pb; R = CH(SiMe3)2, R′= SiMe3, and R″= CMe3], (ii) the linear HgR2 and M′(NR′2)2(M = Zn or Hg), and (iii) the bent momomeric SnCl2 and SnBr2 have been recorded, as well as the reference compounds RH, R′2NH, and R′R″NH For the Group 4 metal(II) alkyls the first vertical ionisation potential (ip) is close to that of the free metal; the metal lone-pair orbital is progressively higher in M(NR′R″), and M(NR′2)2, in which compounds it is the second band, being preceded by the antibonding b2 molecular orbital (mo) formed by the nitrogen lone-pair atomic orbitals (aos) Confirmation of this assignment is also provided by comparison of data for the bent and linear metal(II) amides; in the latter, nitrogen lone-pair interactions are negligible Assignments, on the basis of trends and, for MX2, of CNDO calculations, are prooosed and trends noted There is evidence of substantial N→Si pπ–dπ interaction in the amides
TL;DR: In this article, the authors compared the geometrical variations which occur when a quadridentate Schiff-base co-ordinates to a cobalt(II) atom on the basis of the crystal structure analysis of the ligand NN′-(o-phenylene) bis(salicylideneamine) and its CoII derivative in its orthorhombic (II) and monoclinic (III) modifications.
Abstract: Geometrical variations which occur when a quadridentate Schiff-base co-ordinates to a cobalt(II) atom are compared on the basis of the crystal structure analysis of the ligand NN′-(o-phenylene) bis(salicylideneamine)(I) and its CoII derivative in its orthorhombic (II) and monoclinic (III) modifications. Crystals of (I) are monoclinic, space group P21/c, with cell parameters: a= 6.064(3), b= 16.541(7), c= 13.306(7)A, β= 91.5(1)°. Crystals of (II) are orthorhombic, space group P212121, with a= 16.755(7), b= 17.532(8), c= 5.362(3)A, and of (III) are monoclinic, space group P21/nwith a= 10.681(5), b= 8.354(4), c= 18.185(8)A, β= 105.3(1)°. A total of 1 277 (I). 1 113 (II), and 2 558 (III) independent reflexions were used : the structures were solved from diffractometer data by the heavy-atom method and refined to final R factors of 0.056 (I), 0.046 (II), and 0.041 (III). The enolimine form is established for (I) in the solid state. Upon co-ordination, with formation of (II) and (III), the geometrical data suggest that the contribution to the resonance of a ketamine form becomes as important as that of the enolimine. This is in agreementwith a π-orbital delocalization of the electronic charge over the planar complex molecule.
TL;DR: In this paper, the synthesis and characterization of complexes of the type cis-[FeX2(L4)]+[L4= 1,4,8,11-tetra-azacyclotetradecane (cyclam); X = Cl, Br, and NCS] and trans-[MX2(l4)]+(M = Mn, X = Br, NCS, or N3; M = Fe, X, Cl or NCS: and M = Ni, X or Br) are described.
Abstract: The syntheses and characterization of complexes of the type cis-[FeX2(L4)]+[L4= 1,4,8,11-tetra-azacyclotetradecane (cyclam); X = Cl, Br, and NCS] and trans-[MX2(L4)]+(M = Mn, X = Cl, Br, NCS, or N3; M = Fe, X = Cl, Br, or NCS: and M = Ni, X = Cl or Br) are described. The assignment of geometrical configuration to these complexes is made on the basis of their i.r. spectra in the 790–910 cm–1 region. In some cases, the assignment of a trans configuration to the dihalogeno-complexes is confirmed by the presence of only one ν(M–X) stretching frequency in their far-i.r. spectra. Magnetic susceptibilities show that all the d4 complexes prepared are high spin, whereas d6 and d7 complexes are low spin. For the d5 iron(III) system, all the cis complexes prepared are high spin, whereas trans complexes are low spin. However, trans-[FeBr2(L4)][ClO4] with µ295 3.90 B.M. appears to be in a high-spin–low-spin equilibrium at room temperature. The ambidentate thiocyanate ligand is N-bonded in each case. The electronic and far-i.r. spectra of these complexes are consistent with the electronic structures based on the magnetic properties.
TL;DR: The structure of methylcobaloximes containing pyridine, (I), and 3-N-methylimidazole, (II), together with a single-crystal i.r.
Abstract: The structure of methylcobaloximes containing pyridine, (I), and 3-N-methylimidazole, (II), are reported together with a single-crystal i.r. study of the 3-N-methylimidazole derivative. Structural evidence for a hydroxocobaloxime with 3-N-methylimidazole, (III), is also reported. Crystals of (I) are triclinic, space group P, with cell parameters: a= 14.38(1), b= 10.02(1), c= 9.41(1)A, α= 56.3(1), β= 127.3(1), γ= 106.6(1)°. Crystals of (II) and (III) are both monoclinic, space group P21/c, with cell parameters: (II)a= 9.25(1), b= 11.77(1), c= 19.80(1)A, β= 124.4(1)°; and (III)a= 9.24(1), b= 11.55(1), c= 19.80(1)A, β= 124.3(1)°. A total of 3 083 (I), 1 801 (II), and 1 739 (III) independent reflexions were used; the structures were solved from diffractometer data by the heavy-atom method and refined by least squares to final R factors of 0.064 (I), 0.051 (II), and 0.043 (III). Evidence of structural trans- and cis-effects is reported. Possible correlations between the structural features and chemical behaviour of cobaloximes and analogous quadridentate Schiff-base complexes are discussed.
TL;DR: In the presence of benzene or toluene, similar arene complexes, [RuH(η6-Ar)(PPh3)2][BF4] are obtained as mentioned in this paper.
Abstract: The action of fluoroboric acid on dihydridotetrakis(triphenylphosphine)ruthenium(II) or on acetatohydridotris(tri-phenylphosphine) ruthenium(II) in methanol produces the salt [RuH(η6-C6H5PPh2)(PPh2)3][BF4] in which the phenyl group of one triphenylphosphine molecule is π-bonded to the metal. In the presence of benzene or toluene, similar arene complexes, [RuH(η6-Ar)(PPh3)2][BF4] are obtained.The interaction of RuH2(PPh3)4 with phenol gives a neutral complex, RuH(C6H5O)(PPh3)2, that may also be obtained with two additional molecules of phenol hydrogen bonded to the oxygen atom of the phenoxo-ligand. The C6H5O– ligand can be considered to be bound as an η6-phenoxo or probably more realistically as an η5oxacyclohexadienyl ligand. Re-investigation of the compounds obtained by action of phenol on methyl- or phenyl-tris(triphenyIphosphine)rhodium(I) shows that these also are α-phenoxo-complexes.An η6-toluene-p-sulphonate is also described.I. r., 1H, and 31P n.m.r. spectra of the compounds are given.
TL;DR: The diazenido-complexes [MX(N2H)(dppe)2] and [WBr2(N 2HR)2 ] are derived from the parent diazeneor hydrazido(2)-complexes as mentioned in this paper.
Abstract: The diazenido-complexes [MX(N2H)(dppe)2](M = Mo or W: X = F, Cl, or Br; dppe = Ph2PCH2CH2PPh2) have been prepared by treatment of the corresponding diarene, [MX2(NH:NH)(dppe)2], or hydrazido(2–), [MF(N-NH2)(dppe)2][BF4], complexes with triethylamine or aqueous potassium carbonate. With 1 mol of anhydrous acid they regenerate the parent diazeneor hydrazido(2–) complexes. The complex [WBr(N2H)(dppe)2] reacts with organic bromides to give the known complexes [WBr2(N2HR)(dppe)2](R = Me or MeCO). The N2H ligand is not displaced by trialkylphosphines but nitrogen mono-oxide displaces it quantitatively to give the nitrosyl complexes [MX(NO)(dppe)2]. Spectroscopic data for these complexes and their 15N and 2H derivatives are described.
TL;DR: In this article, the formation constants for cadmium, lead, and zinc with ethylenediaminetetra-acetic acid, 1,2,di(2-aminoethoxy)ethanetetetric acid, glutathione, cysteine, and D-penicillamine at 25 °C, I= 3.00M(NaClO4).
Abstract: Potentiometrically determined formation constants are reported for cadmium(II), lead(II), and zinc(II) with ethylenediaminetetra-acetic acid, 1,2,di(2-aminoethoxy)ethanetetra-acetic acid, glutathione, cysteine, and D-penicillamine at 25 °C, I= 3.00M(NaClO4). Computer-simulated models of blood plasma conditions were used to examine the complexing competition between cadmium(II) and zinc(II), and lead(II) and zinc(II), with these ligands. It was concluded that glutathione is the most promising ligand for future clinical studies.
TL;DR: In this article, the X-ray structures of the title compounds have been determined from diffractometer data by the heavy-atom method and refined by least-squares, and the results showed that the copper co-ordination is tetrhedral and involves the sulphur atoms of four 2-thioimidazolidine (etu) molecules.
Abstract: 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.
TL;DR: In this article, magnetic Mossbauer measurements on SnR2 and [Cr(CO)5(SnR2)] have been carried out and it is shown that the sign of the quadrupole coupling constant eQVzz, is negative and hence Vzz the principal component of the field gradient tensor, is positive.
Abstract: Mossbauer spectra of SnR2[R = CH(SiMe3)2] and of 16 of its derivatives have been recorded. The latter fall into two classes: (i) the dialkylstannylene complexes such as [Cr(CO)5(SnR2)] in which bivalent Sn is three-co-ordinate: and (ii) dialkylstannylene insertion products into C–X, M–H, M–Cl, M–Me, or M–M bonds (M = a transition metal, X = halogen) such as [Fe(η-C5H5)(CO)2(SnR2Cl)], in which quadrivalent tin is four-co-ordinate. The compound SnR2 and class (i) complexes are characterised by isomer shifts of 2.15 ± 0.1 mm s–1 relative to BaSnO3 and large quadrupole splittings [2.31 (for SnR2) or 4.25 ± 0.2 mm s–1 for class (i)]. Class (ii) complexes show lower isomer shifts (1.49 ± 0.25 mm s–1) and quadrupole splittings (<2.37 mm s–1). Magnetic Mossbauer measurements on SnR2 and [Cr(CO)5(SnR2)] show that for both complexes the sign of the quadrupole coupling constant eQVzz, is negative and hence Vzz the principal component of the field gradient tensor, is positive.
TL;DR: In this paper, the influence of solvent and added solute molecules on the nature of the species observed in solutions of the tetrasodium salt of cobalt(II) tetrasulphophthalocyanine has been studied by electronic absorption spectrophotometry.
Abstract: The influence of solvent and added solute molecules on the nature of the species observed in solutions of the tetrasodium salt of cobalt(II) tetrasulphophthalocyanine has been studied by electronic absorption spectrophotometry. Water is the only solvent which promotes formation of the known dimeric species. The equilibrium between monomer (M) and dimer(D) obeys the relationship K=[D]/[M]2·[H2O]n where n≃ 12 in both water–methanol and water–ethanol mixtures. It is suggested that the water molecules play a specific role in binding together the two monomer units through the formation of hydrogen bonds.
TL;DR: In this article, the crystal structures of Ag2Mo2O7(I) and Ag2W2O 7(II) have been determined by single-crystal X-ray analysis.
Abstract: The crystal structures of Ag2Mo2O7(I) and Ag2W2O7(II) have been determined by single-crystal X-ray analysis Both compounds crystallize in space group P, Z= 2, with for (I): a= 6095(3), b= 7501(3), c= 7681(3)A, α= 1104(1), β= 933(1), γ= 1135(1)°; and for (II): a = 6033(3), b= 7051 (3), c= 7735(3)A, α= 738(1), β= 922(1), γ= 1047(1)° The structures were determined from diffractometer data by heavy-atom methods and refined to R 0045 [(I), 1 208 observed reflections] and 0047 [(II), 1 364 observed reflections] The structures consist of infinite chains formed by blocks of four edge-shared octahedra joined by edge-sharing in (I), and by corner-sharing in (II), with the silver ions situated between the chains