Tetraphenylarsonium Cation Research Articles

Dimethyl Derivatives of 2,2'-Bipyridine as Ligands in [W(CN)6(bpy)]2--Type Complexes.

The thermal decomposition of (XMebpyH)3(H3O)[W(CN)8]·3H2O (where XMebpy denotes 4Mebpy 4,4'-dimethyl-2,2'-bipyridine or 5Mebpy 5,5'-dimethyl-2,2'-bipyridine) in glycerol results in the coordination of XMebpy. Salts of the anion formula [W(CN)6(XMebpy)]2- were isolated for PPh4+ and/or AsPh4+ cations as well as for K+, Rb+, and Cs+ ones. X-ray single-crystal analyses for tetraphenyl-phosphonium and tetraphenyl-arsonium cations are described. IR, UV-Vis, and cyclic voltammetry data are presented. The results were compared with those for [W(CN)6(bpy)]2- (bpy = 2,2'-bipyridine) ion salts.

Chromium(III) complexes with 2-(2′-pyridyl)imidazole: Synthesis, crystal structure and magnetic properties

The preparation, crystal structure and variable temperature-magnetic investigation of three 2-(2′-pyridyl)imidazole-containing chromium(III) complexes of formula PPh4[Cr(pyim)(C2O4)2]·H2O (1), AsPh4[Cr(pyim)(C2O4)2]·H2O (2) and [Cr2(pyim)2(C2O4)2(OH2)2]·2pyim · 6H2O (3) [pyim=2-(2′-pyridyl)imidazole, C2O42-=dianion of oxalic acid, PPh4+=tetraphenylphosphonium cation and AsPh4+=tetraphenylarsonium cation] are reported herein. The isomorphous compounds are made up of discrete [Cr(pyim)(C2O4)2]− anions, XPh4+ cations [X=P (1) and As (2)] and uncoordinated water molecules. The chromium environment in 1 and 2 is distorted octahedral with Cr–N and Cr–O bond distances varying in the ranges 2.040(3)–2.101(3) and 1.941(3)–1.959(3)Å, respectively. The angle subtended by the chromium(III) ion by the two didentate oxalate ligands cover the range 82.49(12)–82.95(12)°, values which are somewhat greater than those concerning the chelating pyim molecule [77.94(13) (1) and 78.50(13)° (2)]. Complex 3 contains discrete centrosymmetric [Cr2(pyim)2(C2O4)2(OH)2] neutral units where the two chromium(III) ions are joined by a di-μ-hydroxo bridge, the oxalate and pyim groups acting as peripheral didentate ligands. Uncoordinated water and pyim molecules are also present in 3 and they contribute to the stabilization of its structure by extensive hydrogen bonding and π–π type interactions. The values of the intramolecular chromium–chromium separation and angle at the hydroxo bridge in 3 are 2.9908(12)Å and 99.60(16)°, respectively. Magnetic susceptibility measurements of 1–3 in the temperature range 1.9–300K show the occurrence of weak inter- (1 and 2) and intramolecular (3) antiferromagnetic couplings. The magnetic properties of 3 have been interpreted in terms of a temperature-dependent exchange integral, small changes of the angle at the hydroxo bridge upon cooling being most likely responsible for this peculiar magnetic behavior.

Cr(dmbipy)(ox)2]−: a new bis-oxalato building block for metal assembling. Crystal structures and magnetic properties of XPh4[Cr(dmbipy)(ox)2]·5H2O (X = P and As), {Ba(H2O)2[Cr(dmbipy)(ox)2]2}n·17/2nH2O and {Ag(H2O)[Cr(dmbipy)(ox)2]}n·3nH2O

The synthesis, X-ray structure and variable-temperature magnetic study of new compounds of formula PPh4[Cr(dmbipy)(ox)2]·5H2O (1), AsPh4[Cr(dmbipy)(ox)2]·5H2O (2), {Ba(H2O)2[Cr(dmbipy)(ox)2]2}n·17/2nH2O (3) and {Ag(H2O)[Cr(dmbipy)(ox)2]}n·3nH2O (4) (PPh4+ = tetraphenylphosphonium cation; AsPh4+ = tetraphenylarsonium cation; dmbipy = 4,4′-dimethyl-2,2′-bipyridine; ox2− = oxalate dianion) are reported herein. The isomorphous compounds 1 and 2 are made up of discrete [Cr(dmbipy)(ox)2]− anions, XPh4+ cations [X = P (1) and As (2)] and uncoordinated water molecules. The chromium environment in 1 and 2 is distorted octahedral with Cr–O and Cr–N bond distances varying in the ranges 1.950(2)–1.9782(12) and 2.047(3)–2.0567(14) Å, respectively. The angles subtended at the chromium atom by the two bidentate oxalate ligands cover the range 82.58(10)–83.11(5)°, and they are somewhat greater than those concerning the chelating dmbipy [79.04(10) (1) and 79.24(5)° (2)]. The [Cr(dmbipy)(ox)2]− unit of 1 and 2 also occurs in 3 and 4 but it adopts different coordination modes. It acts as a chelating ligand through its two oxalate groups towards the divalent barium cations in 3 affording neutral chains with diamond-shaped units sharing the barium atoms, while the two other corners are occupied by two crystallographically independent chromium atoms. The barium atom in 3 is coordinated by eight oxygen atoms from four oxalate groups and two aqua ligands. The structure of 4 consists of neutral bimetallic layers where the [Cr(dmbipy)(ox)2]− unit acts as a ligand towards the univalent silver(I) cation through its two oxalate groups, one of them being bidentate and the other bidentate/monodentate (outer). Each silver atom is six-coordinated with a water molecule and five oxygen atoms from three oxalate groups building a highly distorted octahedral environment. Magnetic susceptibility measurements for 1–4 in the temperature range 1.9–300 K show the occurrence of weak ferro- (1 and 2) and antiferromagnetic (3 and 4) interactions which are mediated by π–π stacking between dmbipy ligands through the spin polarization mechanism. A comparative study of the potentiality of the [Cr(AA)(ox)2]− unit (AA = bidentate nitrogen donor) as a building block for designing heterometallic species is carried out in the light of the available structural information.

Treating [K4(H2O)0.5][SnTe4] with PPh4+ or AsPh4+: Formation of a Highly Air‐Stable Tellurostannate Salt, a Tellurolate with One‐Coordinate Te Atoms, and a Polytelluride Salt with ∞1[Te4(H2O)2]2– Chains

AbstractIn reactions of potassium orthotellurostannates with EPh4Cl (E = P, As), different single‐crystalline products are obtained. An air‐stable dimeric tellurostannate forms by partial replacement of strongly interacting K+ cations by weakly interacting or noninteracting [PPh4]+ ions. For E = As, an equally air‐stable tellurophenolate, in which Te has the rare coordination number 1, results upon As–C bond cleavage at a tetraphenylarsonium cation. Oxidation of the air‐sensitive [Sn2Te6]4– anion and Te2– by O2 (air) affords a tetratelluride salt with strands of H2O‐bridged [Te4]2– anions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

4,2-Ribbon like ferromagnetic cyano-bridged FeIII2NiII chains: a magneto-structural study

The low-spin iron(III) complex AsPh(4)[Fe(III)(bpy)(CN)(4)].CH(3)CN (1) [AsPh(4) = tetraphenylarsonium cation] and the heterobimetallic chains [{Fe(III)(L)(CN)(4)}(2)Ni(II)(H(2)O)(2)].4H(2)O with L = bpy (2) and phen (3) [bpy = 2,2'-bipyridine and phen = 1,10-phenanthroline] have been prepared and their structures determined by X-ray diffraction methods. The structure of 1 consists of mononuclear [Fe(bpy)(CN)(4)](-) anions, tetraphenylarsonium cations and acetonitrile molecules of crystallization. The iron(III) is hexacoordinated with two nitrogen atoms of the bidentate bpy and four carbon atoms of four terminal cyanide groups building a distorted octahedral surrounding around the metal atom. 2 and 3 are isomorphous compounds whose structure is made up of neutral 4,2-ribbon like bimetallic chains of formula [{Fe(III)(L)(CN)(4)}(2)Ni(II)(H(2)O)(2)] where the [Fe(III)(L)(CN)(4)](-) unit acts as a bis-monodentate bridging ligand toward the trans-diaquanickel(II) units through two of its four cyanide groups in cis positions. The chains exhibit two orientations in the unit cell and they interact with each other through hydrogen bonds involving the coordination and crystallization water molecules together with the uncoordinated cyanide nitrogen atoms of the [Fe(L)(CN)(4)](-) units. Compounds 2 and 3 behave as ferromagnetic Fe(III)(2)Ni(II) chains which interact ferromagnetically at very low temperatures in the case of 2, whereas metamagnetic-like behaviour is observed for with a critical field (H(c)) around 200 G. For H > H(c) the ferromagnetic Fe(III)(2)Ni(II) chains of 3 exhibit a frequency dependence of the out-of-phase ac susceptibility signal at T < 3.5 K.

Malonate-Containing Manganese(III) Complexes: Synthesis, Crystal Structure, and Magnetic Properties of AsPh4[Mn(mal)2(H2O)2

The novel manganese(III) complexes PPh4[Mn(mal)2(H2O)2] (1) and AsPh4[Mn(mal)2(H2O)2] (2) (PPh4+ = tetraphenylphosphonium cation, AsPh4+ = tetraphenylarsonium cation, and H2mal = malonic acid) have been prepared, and the structure of 2 was determined by X-ray diffraction analysis. 2 is a mononuclear complex whose structure is made up of trans-diaquabis(malonato)manganate(III) units and tetraphenylarsonium cations. Two crystallographically independent manganese(III) ions (Mn(1) and Mn(2)) occur in 2 that exhibit elongated octahedral surroundings with four oxygen atoms from two bidentate malonate groups in equatorial positions (Mn(1)-O = 1.923(6) and 1.9328(6) A and Mn(2)-O = 1.894(6) and 1.925(6) A) and two trans-coordinated water molecules in the axial sites (Mn(1)-Ow = 2.245(6) A and Mn(2)-Ow = 2.268(6) A). The [Mn(mal)2(H2O)2]- units are linked through hydrogen bonds involving the free malonate-oxygen atoms and the coordinated water molecules to yield a quasi-square-type anionic layer growing in the ab plane. The shortest intralayer metal-metal separations are 7.1557(7) and 7.1526(7) A (through the edges of the square). The anionic sheets are separated from each other by layers of AsPh4+ where sextuple- and double-phenyl embraces occur. The magnetic behavior of 1 and 2 in the temperature range 1.9-290 K reveals the occurrence of weak intralayer ferromagnetic interactions (J = +0.081(1) (1) and +0.072(2) cm(-1) (2)). These values are compared to those of the weak antiferromagnetic coupling [J = -0.19(1) cm(-1)], which is observed in the chain compound K2[Mn(mal)2(MeOH)2][Mn(mal)2] (3), where the exchange pathway involves the carboxyate-malonate bridge in the anti-syn conformation. The structure of 3 was reported elsewhere. Theoretical calculations on fragment models of 2 and 3 were performed to analyze and substantiate both the nature and magnitude of the magnetic couplings observed.

Bis and tris(oxalato)ferrate(iii) complexes as precursors of polynuclear compounds

The preparation and crystal structure of two oxalato-bridged NaI–FeIII compounds, [Na3Fe(ox)3(H2O)4]·H2O (1) and [FeII(phen)3][NaFe(ox)3(H2O)3]·4H2O (5), two mononuclear FeIII complexes AsPh4[Fe(bipy)(ox)2]·H2O (3) and AsPh4[Fe(phen)(ox)2]·H2O (4) and an oxalato-bridged FeIII compound [AsPh4]4[Fe2(ox)5]·5H2O (2) (ox = oxalate dianion, bipy = 2,2′-bipyridine, phen = 1,10-phenantroline and AsPh4+ = tetraphenylarsonium cation) are reported here. The structure of 1 consists of infinite anionic [NaFe(ox)3]2− layers linked trough centrosymmetric [Na4(H2O)8]4+ tetranuclear units yielding a three-dimensional motif. Crystallization water molecules ensure the cohesion of the crystal lattice in 1. The iron environment is distorted octahedral being surrounded by six oxygen atoms of three oxalate groups, with an average iron to oxalate-oxygen bond distance of 2.012(3) A. There are four crystallographically independent sodium atoms, all of which have a highly distorted octahedral environment. Six oxalate-oxygen atoms are bound to Na(1) and Na(2), whereas the other two sodium atoms are surrounded by four water oxygen and two oxalate oxygen atoms [Na(3)] and three water oxygen and three oxalate oxygen atoms [Na(4)]. The structure of compound 2 consists of centrosymmetric dinuclear [Fe2(ox)5]4− anions, AsPh4+ cations and crystallization water molecules. The anionic unit contains two Fe(III) atoms, four bidentate and one bridging oxalato ligands. Each iron atom has a distorted octahedral environment. The structures of 3 and 4 consist of discrete [Fe(AA)(ox)2]− [AA = bipy (3) and phen (4)] anions, tetraphenylarsonium cations and uncoordinated water molecules which are linked by hydrogen bonds. Each iron atom is six-coordinated with two nitrogen atoms from the bidentate AA ligand and four oxalate-oxygen atoms building a distorted octahedral environment. The structure of compound 5 consists of anionic [Fe(ox)3Na(H2O)3]2− chains, tris-chelated low-spin iron(II) [Fe(phen)3]2+ units and lattice water molecules linked to the chains through hydrogen bonds in which the water molecules and oxygen atoms of the oxalate groups are involved. The chains contain Fe3+ and Na+ cations alternatively bridged by oxalate groups, the tris-chelated [Fe(ox)3]3− unit acting as a bidentate ligand through one oxalato group toward a central sodium atom. Magnetic susceptibilty measurements in the temperature range 2.0–290 K for 2 that reveal the occurrence of antiferromagnetic coupling (J = −6.5 cm−1, the Hamiltonian being defined as H = −JS1S2) between the high-spin iron(III) ions across the oxalato bridge.

Rhenium(IV)−Copper(II) Heterobimetallic Complexes with a Bridge Malonato Ligand. Synthesis, Crystal Structure, and Magnetic Properties

The Re(IV) complex [ReCl4(mal)]2-, in the form of two slightly different salts, (AsPh4)1.5(HNEt3)0.5[ReCl4(mal)] (1a) and (AsPh4)(HNEt3)[ReCl4(mal)] (1b), and the Re(IV)-Cu(II) bimetallic complexes [ReCl4(mu-mal)Cu(phen)2].CH3CN (2), [ReCl4(mu-mal)Cu(bpy)2] (3), and [ReCl4(mu-mal)Cu(terpy)] (4) (mal=malonate dianion, AsPh4=tetraphenylarsonium cation, HNEt3=triethylammonium cation, phen=1,10-phenanthroline, bpy=2,2'-bipyridine and terpy=2,2':6',2' '-terpyridine) have been synthesized and the structures of 1a, 1b, 2, and 3 determined by single-crystal X-ray diffraction. The structures of 1a and 1b are made up of discrete [ReCl4(mal)]2- anions and AsPh4+ and HNEt3+ cations, held together by electrostatic forces and hydrogen bonds. The Re(IV) atom is surrounded by four chloride anions and a bidentate malonate group, in a distorted octahedral environment. The structure of 2 consist of neutral dinuclear units [ReCl4(mu-mal)Cu(phen)2], with the metal ions united through a bridge carboxilato. The environment of Re(IV) is nearly identical to that in the mononuclear complex, and Cu(II) is five coordinate, being surrounded by four nitrogen atoms of two bidentate phen ligands and one oxygen atom of the malonato ligand. In 3, there are also dinuclear units, [ReCl4(mu-mal)Cu(bpy)2], but the Cu(II) ions complete a distorted octahedral coordination by binding with the free malonato oxygen atom of a neighbor unit, resulting in an infinite chain. The magnetic properties of 1-4 were also investigated in the temperature range 2.0-300 K. The magnetic behavior of 1a and 1b is as expected for a Re(IV) complex with a large value of the zero-field splitting (2D ca. 110 cm(-1)). For the bimetallic complexes, the magnetic coupling between Re(IV) and Cu(II) is antiferromagnetic in 2 (J=-0.39 cm(-1)), ferromagnetic in 4 (J=+1.51 cm(-1)), and nearly negligible in 3 (J=-0.09 cm(-1)).

Magnetic Studies on Hexaiodorhenate(IV) Salts of Univalent Cations. Spin Canting and Magnetic Ordering in K2[ReI6] with Tc = 24 K.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Magnetic studies on hexaiodorhenate(IV) salts of univalent cations. Spin canting and magnetic ordering in K2[ReI6] with Tc = 24 K.

The ionic salts of rhenium(IV) of formula (Cat)(2)[ReI(6)] with Cat = Li(+) (1), Na(+) (2), K(+) (3), Rb(+) (4), Cs(+) (5), NH(4)(+) (6), and AsPh(4)(+) (7) [AsPh(4)(+) = tetraphenylarsonium cation] have been synthesized, and the structures of two of them (namely, 3 and 6) were determined by single-crystal X-ray diffraction. 3 crystallizes in the monoclinic system, space group Pn, with a = 7.815(1) A, b = 7.874(1) A, c = 11.335(1) A, beta = 90.38(1) degrees, and Z = 2 whereas 6 crystallizes in the tetragonal system, space group P4/mnc, with a = 7.881(1) A, b = 7.881(1) A, c = 11.474(2) A, and Z = 2. The structures of 3 and 6 are made up of discrete [ReI(6)](2)(-) anions and K(+) (3) or NH(4)(+) (6) cations held together by electrostatic forces (3 and 6) and N-H.I hydrogen bonds (6). The rhenium(IV) cation in 3 and 6 is surrounded by six iodide ligands in an octahedral environment with the Re-I bond lengths varying in a very narrow range [2.704(3)-2.738(3) and 2.716(1)-2.722(2) A for 3 and 6, respectively]. The [ReI(6)](2)(-) anions in 6 describe a tetragonally distorted body-centered cubic structure. In 3, the arrangement of these units is similar but more distorted. The different arrangement of the anions in 3 and 6 accounts for the centrosymmetric (6) and non-centrosymmetric (3) structures observed. The magnetic properties of 1-7 were investigated in the temperature range 2.0-300 K. The magnetic behavior of 7 is that of a magnetically diluted Re(IV) complex with a large value of the zero-field splitting of the ground level (|2D| = 49.8 cm(-)(1)) whereas those of 1, 2, and 4-6 are typical of antiferromagnetically coupled systems with susceptibility maxima at 28 (1), 27 (2), 21 (4), 16 (5), and 20 K (6). In the case of compound 3, its magnetic behavior in the high-temperature range is parallel to that observed in the parent salts but below 24 K it is a weak ferromagnet with a canting angle of ca. 1.2 degrees.

Synthesis, Crystal Structure, and Magnetic Properties of Tetraphenylarsonium Tetrachloro(oxalato)rhenate(IV) and Bis(2,2'-bipyridine)tetrachloro(&mgr;-oxalato)copper(II)rhenium(IV).

Two new rhenium(IV) compounds of formula (AsPh(4))(2)[ReCl(4)(ox)] (1) and [ReCl(4)(&mgr;-ox)Cu(bipy)(2)] (2) (AsPh(4) = tetraphenylarsonium cation, ox = oxalate anion, and bipy = 2,2'-bipyridine) have been synthesized and their crystal structures determined by single-crystal X-ray diffraction. 1 and 2 crystallize in the monoclinic system, space groups P2(1)/c and P2(1)/n, respectively, with a = 22.250(5) Å, b = 11.245(3) Å, c = 19.089(4) Å, beta = 96.59(2) degrees, and Z = 4 for 1 and a = 9.421(2) Å, b = 16.909(4) Å, c = 16.179(4) Å, beta = 93.97(2) degrees, and Z = 4 for 2. The structure of 1 is made up of [ReCl(4)(ox)](2)(-) anions and AsPh(4)(+) cations held united by electrostatic forces. Rhenium(IV) is hexacoordinate, with two oxygens of a chelating ox and four chlorine atoms building a distorted octahedron around the metal atom. There is no contact between the [ReCl(4)(ox)](2)(-) anions, the shortest Re.Re and Cl.Cl distances being 10.345 and 7.209 Å, respectively. This anionic complex is coordinated to a [Cu(bipy)(2)](2+) cation in 2, through one oxalate-oxygen, giving a neutral heterometallic dinuclear unit. The Cu(II) ion shows a very distorted five-coordinated geometry, four bipy-nitrogens occuping the equatorial positions and the oxygen atom the apical one. The basal plane geometry is distorted toward the tetrahedron, the dihedral angle between the mean planes of the two bipy ligands is 37.6(2) degrees. These [ReCl(4)(&mgr;-ox)Cu(bipy)(2)] units are arranged in such a way that a chlorine atom of one of them points toward the copper atom of the neighboring one, forming helicoid chains. The intrachain Re.Cu distances through chloro and oxalato bridges are 4.658 and 4.798 Å, respectively. The magnetic behavior of 1 and 2 has been investigated over the temperature range 1.8-300 K. 1 is a magnetically diluted Re(IV) complex, the great value of zero-field splitting of the ground level (D = 60 cm(-)(1)) accounting for the variation of chi(M)T with T in the low-temperature range. 2 behaves as a ferrimagnetic chain, with weak antiferromagnetic interactions between Re(IV) and Cu(II) through oxalato and single chloro bridges.

Influence of the counterion on the coordinating properties of (2,2′-bipyridyl)bis(oxalato)chromate(III) anion: crystal structures and magnetic properties of AsPh4[Cr(bipy)(ox)2]·H2O and [NaCr(bipy)(ox)2(H2O)]·2H2O

Two new chromium(III)-containing complexes of formula AsPh4[Cr(bipy)(ox)2]·H2O 1 and [NaCr(bipy)(ox)2(H2O)]· 2H2O 2 (bipy = 2,2′-bipyridine and ox = oxalate dianion) have been synthesized and characterized by single-crystal X-ray diffraction. The structure of 1 consists of discrete [Cr(bipy)(ox)2]– mononuclear anions, tetraphenylarsonium cations and uncoordinated water molecules. The structure of 2 reveals a novel two-dimensional framework which is made up of oxalato-bridged bimetallic CrIII–NaI helical chains which are interconnected through centrosymmetric Na2O2 units. Within the chain, a regular alternation of the metal ions is observed, the oxalate group acting as a bis(chelating) ligand. In addition to this coordination mode, two oxalates each act as monodentate ligands towards a sodium atom of a neighbouring chain thus leading to a sheetlike polymeric structure. The chromium environment is distorted octahedral in both complexes: two nitrogen atoms from a bidentate bipy ligand and four oxygen atoms from either two chelating (1) or two bis(chelating) (2) oxalate groups build the coordination polyhedron around the chromium atom. The Cr–N bond lengths [values in the ranges 2.077(3)–2.057(3) (1) and 2.067(4)–2.058(4) A (2)] are somewhat longer than the Cr–O ones [values in the ranges 1.960(2)–1.946(2) (1) and 1.968(3)–1.949(3) A (2)]. The sodium atom in 2 is also six-coordinated: a coordinated water molecule [2.371(5) and 2.325(4) A for Na(1)–O(17) and Na(2)–O(18), respectively] and five oxygens from three oxalate groups [values of the Na–O (ox) bonds in the ranges 2.511(4)–2.331(4) and 2.481(4)–2.364(4) A around Na(1) and Na(2), respectively] build a distorted octahedral NaO6 environment. The intralayer chromium–sodium and sodium–sodium distances through bridging oxalate in 2 vary in the ranges 5.657(4)–5.579(2) and 3.534(3)–3.497(4) A, respectively. Variable-temperature magnetic susceptibility measurements of 1 and 2 reveal the occurrence of very weak antiferromagnetic interactions together with zero-field splitting effects in both compounds. The use of the [Cr(bipy)(ox)2]– unit as a ligand towards different univalent and divalent metal ions aimed at designing new heterobimetallic systems is analysed and discussed in the light of available structural data.

Enhancement of phenols on ion-pair extraction of chromium(VI) with tetraphenylarsonium

The effect of phenols on the ion-pair extraction of chromium(VI) as chromate anion (HCrO 4 − ) with tetraphenylarsonium cation (TPA+) has been investigated. By using TPACl, chromate is extracted as an ion-pair, TPA+·HCrO 4 − , into organic solvents, but its extractability into nonpolar solvents such as carbon tetrachloride is very low. The addition of several phenols greatly enhances the extractability, e.g., the distribution ratio of chromium(VI) between carbon tetrachloride and water rises 5500-fold in the presence of 0.020M 3,5-dichlorophenol in the organic phase. The enhancement was larger when using more acidic phenols and less polar solvents. From the analysis of the extraction data for the 3,5-dichlorophenol-carbon tetrachloride system, it was shown that one molecule of chromate is extracted together with one TPA+ and 1–3 phenol molecules and the extraction constants were determined. The UV spectrum indicated the extracted species including chromate ester to the TPA+·ArOCrO 3 − ·mArOH (m=1,2).

Individual extraction constants of some dicarbollylcobaltate anions in the water-nitrobenzene system

Individual extraction constants of nine dicarbollylcobaltate anions in the two-phase water-nitrobenzene system were determined radiometrically assuming that the changes of Gibbs energy of the transfer of the tetraphenylarsonium cation, Ph4As+, and of the tetraphenylborate anion, BPh 4 − , from the aqueous into the nitrobenzene phase are equal. The constants obtained by this method were correlated with Hansch's constants of hydrophobity.

Vibrational spectra of metal salts of bis(2-ethylhexyl)sulfosuccinate (AOT)

The vibrational spectra of sodium bis(2-ethylhexyl)sulfosuccinate (NaAOT), and NaAOT exchanged with alkali-metal (Li+, K+, Rb+, Cs), Ba2+ and Ce3+ and tetraphenylarsonium (TPA+) cations have been investigated. The effect of the charge-to-radius ratio of the counterion on the symmetric and antisymmetric sulfonate stretching modes has been studied to obtain a more comprehensive assignment of these modes for NaAOT. The symmetric sulfonate stretching mode shifted to lower wavenumber with increasing counterion radius, due to a decrease in the interaction between the cation and the SO3– group. A difference was observed between the IR and Raman spectra for the wavenumber of the symmetric sulfonate stretching mode, which was attributed to correlation coupling. This difference also decreased with increasing counterion radius. In the limiting case involving the large (TPA+) counterion, the symmetric sulfonate stretching mode appeared at the same wavenumber in the Raman and IR spectra. The spectrum of a model compound, bis(2-ethylhexyl)succinate (i.e. NaAOT without the sulfonate moiety), was used to assign bands in the 1300–1100 cm–1 region of the IR spectrum of NaAOT. This region consists of C–C and C–O stretching modes associated with the succinate backbone, and non-degenerate, antisymmetric stretching modes of the SO3– group. The correlation splitting yields four antisymmetric sulfonate stretching modes. The splitting decreases with increasing counterion radius, due to a reduction in the interaction between the cation and the SO3– group. The doubly degenerate, antisymmetric sulfonate stretching mode appeared as a single, broad band in the spectrum of (TPA)AOT. The carbonyl stretching mode of NaAOT appears as an asymmetric band between 1720 and 1740 cm–1. This asymmetry was attributed to different conformations about the acyl C–C bond. Weak interactions between the Na+ counterion and the carbonyl group may also contribute to the intensity of the lower-wavenumber band.

Absolute structure of a new paramagnetic platinum(II)-creatinine complex with a columnar structure

A new platinum complex with creatinine [C 3H 2 N 2(O)(CH 3)NH 2] exhibiting paramagnetic properties was synthesized fully characterized by crystallographic, spectral magnetic measurements. The compound [AsPh 4] +[Pt(creatinine)Cl 3] − crystallizes to give a columnar honeycomb motif of tetraphenylarsonium cations with the channels occupied by creatinine anions. The shortest Pt-Pt distance is 7.622(1). A remarkable feature of the structure is the formation of short Ptμ H intermolecular bonds of 2.73(2) Å. The temperature dependence of both μ eff and EPR parameters of the complex has been studied.

Solvent extraction of tetraphenylarsonium ion pairs from mixed aqueous-organic solutions

Ion pairs of tetraphenylarsonium cation with iodide, bromide, and perrhenate anions were extracted into chloroform from mixed aqueous-organic solutions. The extraction of these ion pairs was found to increase in the presence of polar aprotic solvents in the mixed aqueous-organic phase. This effect was correlated with literature data on free energy of transfer of the Ph4As+ ion, and ascribed to ion pair/solvent and/or ion/solvent interactions in the organic phase.

Preparation and characterisation of tetraphenylphosphonium and tetraphenylarsonium halogenoargentates(I), including a new lodoargentate(I) cluster, [Ag4I8]4–, containing three- and four-co-ordinated silver(I)

A new iodoargentate(I) cluster [Ag4I8]4–, containing three- and four-co-ordinated silver(I) has been isolated with the tetraphenylphosphonium and tetraphenylarsonium cations and characterised by means of crystal structure determination. Tetrakis(tetraphenylphosphonium) and tetrakis(tetraphenylarsonium) hexa-µ-iodo-di-iodotetra-argentate(I)[(1) and (2)] are isostructural and crystallise in the triclinic space group P, with a= 13.453(7), b= 16.607(9), c= 11.068(7)Å, α= 102.83(4), β= 103.94(4), γ= 82.96(4)°, Z= 1, and a= 13.446(3), b= 16.712(3), c= 11.293(4)Å, α= 103.36(2), β= 103.84(2), γ= 83.43(2)°, Z= 1, respectively. The initial phases crystallising from solution during formation of [PPh4]4[Ag4I8] and [AsPh4]4[Ag4I8] are [PPh4][Ag3I4](3) and [AsPh4][Ag3I4](4), respectively. The latter compounds are also isostructural with one another and crystallise in the monoclinic space group P21/c with Z= 4 and a= 13.380(5), b= 26.536(5), c= 8.504(4)Å, β= 108.09(4)° for (3), and a= 13.448(7), b= 26.723(4), c= 8.546(4), β= 107.99(4)° for (4). With tetraphenylarsonium as cation, discrete chloroargentate(I) and bromoargentate(I) anions, [Ag2X4]2–, X = Cl (5) or Br (6), containing distorted trigonal-planar co-ordinated silver(I), have been obtained. Bis(tetraphenylarsonium)di-µ-chloro-dichlorodiargentate(I)(5) and bis(tetraphenylarsonium) di-µ-bromo-dibromodiargentate(I)(6) both crystallise in the monoclinic space group P21/n with Z= 2 and a= 14.280(6), b= 8.200(4), c= 19.118(8)Å, β= 101.19(3)°, and a= 14.546(4), b= 8.072(2), c= 19.854(5)Å, β= 102.73(2)°, respectively. The tetranuclear [Ag4I8]4– anion is centrosymmetric and can be described in terms of two edge-sharing silver(I)–iodide tetrahedra, each linked via a common edge to an approximately planar silver(I)–iodide triangle. In the latter the silver(I) atom is displaced 0.054(1)(1) and 0.026(1)Å(2) from the plane through the three iodide ligands. The Ag–I distances associated with the three-co-ordinated centre are 2.727(2), 2.763(2), and 2.765(2)Å(1), and 2.721 (1), 2.757(1), and 2.766(1)Å(2), while those involving the four-co-ordinated centre range from 2.842(2) to 2.991 (2)(1) and 2.846(1) to 2.973(1)Å(2). The Ag ⋯ Ag separations are 3.171 (2) and 3.256(2), and 3.198(1) and 3.306(2)Å in (1) and (2), respectively. The [Ag3I4]– polymers in [PPh4][Ag3I4](3) and [PPh4][Ag3I4](4) consist of triple chains of edge-sharing Ag–I tetrahedra, Ag–I distances ranging from 2.796(2)–2.972(3)(3) and 2.798(4)–2.966(4)Å(4). The anions in [AsPh4]2[Ag2Cl4] and [AsPh4]2[Ag2Br4] are centrosymmetric, approximately planar entities in which silver(I) is displaced 0.004(1)(5) and 0.048(1)Å(6) from the ligand plane, and the Ag ⋯ Ag separations are 3.659(2)(5) and 3.549(2)Å(6). In [Ag2Cl4]2–, the bridging Ag–Cl distances differ considerably from one another, i.e. 2.446(2) and 2.809(2)Å, the terminal Ag–Cl bond being 2.359(2)Å. In [Ag2Br4]2–, there is less discrepancy between bridging distances: 2.614(1) and 2.741 (1)Å; Ag–Br(terminal) is 2.481 (1)Å.

The thermodynamics of solvation of ions. Part 4.—Application of the tetraphenylarsonium tetraphenylborate (TATB) extrathermodynamic assumption to the hydration of ions and to properties of hydrated ions

The tetraphenylarsonium tetraphenylborate (TATB) assumption, i.e. that thermodynamic and other quantities pertaining to the tetraphenylarsonium cation equal those pertaining to the tetraphenylborate anion, is applied to the standard enthalpy, entropy and Gibbs energy of hydration of ions, the standard partial molar heat capacity and volume of aqueous ions, and their equivalent conductivities and Dole–Jones B-coefficients of viscosity at infinite dilution, all at 298.15 K. The effect of uncertainties due to the non-equality in size of the TATB ions is discussed, and related to the relative magnitude of the quantity for small ions and for the constituent ions of TATB, as a criterion for the acceptance of the assumption.

An Adsorption Procedure for Determining the Level of Organophosphorus Pesticide Residues in Pond Water

Abstract A procedure for the accumulation of phosphorus-containing degradation products of organophosphorus pesticides from water by elution of ion-associates of dialkylphosphorus anions with tetraphenylarsonium cation adsorbed onto an activated carbon micro-column is described. Using a 50cm3 sample volume at a concentration of 1 μcm−3 the average accumulation recoveries (%±S.D.) were 81±11 and 91±8 for diethyl and dimethyl phosphorodithioates, 69±10 and 66±10 for the corresponding phosphorothioates and 33±13 and 13±6 for the analogous phosphates. A decrease in these values was caused by the presence of common inorganic anions and at lower concentrations of the analysed species. At a detection limit of 20 ng cm−3 the recovery was 20–30%. Despite of low accumulation recoveries the minimum detectable concentration of these anions was decreased below 0.1 ng cm−3 by handling 1 dm3 sample volumes. The procedure was applied for the analysis of dialkyl phosphorothioates and dialkyl phosphorodithioates in the wat...