Mercury(II) cyanide complexes with alkyldiamines: solid-state/solution NMR,computational, and antimicrobial studies

Mercury cyanide complexes of alkyldiamines (1–6), [Hg(L)(CN)₂] (where L?=?en (1,2-diaminoethane), pn (1,3-diaminopropane), N-Me-en, N, N′-Me₂-en, N, N′-Et₂-en, and N, N′-ipr₂-en), have been synthesized and characterized by elemental analysis, IR, ¹³C, and ¹⁵N solution NMR in DMSO-d₆, as well as ¹³C, ¹⁵N, and ¹⁹⁹Hg solid-state NMR spectroscopy. Complexes 1 and 2 have been studied computationally, built and optimized by GAUSSIAN03 using DFT at B3LYP level with LanL2DZ basis set. Binding modes of en and bn (where bn?=?1,4-diaminobutane) toward Hg(CN)₂ are completely different. Complexes with en and pn show chelating binding to Hg(II), while bn behaves as a bridging ligand to form a polymeric structure, [Hg(CN)₂-bn]_∞ [B.A. Al-Maythalony, M. Fettouhi, M.I.M. Wazeer, A.A. Isab. Inorg. Chem. Commun., 12, 540 (2009).]. The solution ¹³C NMR of the complexes demonstrates a slight shift of the ?C≡N (0.9 to 2?ppm) and ?C–NH₂ (0.25 to 6?ppm) carbon resonances, while the other resonances are relatively unaffected. ¹⁵N labeling studies have shown involvement of alkyldiamine ligands in coordination to the metal. The principal components of the ¹³C, ¹⁵N, and ¹⁹⁹Hg shielding tensors have been determined from solid-state NMR data. Antimicrobial activity studies show that the complexes exhibit higher antibacterial activities toward various microorganisms than Hg(CN)₂.     

Desymmetrization of an Octahedral Coordination Complex Inside a Self‐Assembled Exoskeleton

The synthesis of a centrally functionalized, ribbon‐shaped [6]polynorbornane ligand L that self‐assembles with Pd^II cations into a {Pd₂ L ₄} coordination cage is reported. The shape‐persistent {Pd₂ L ₄} cage contains two axial cationic centers and an array of four equatorial H‐bond donors pointing directly towards the center of the cavity. This precisely defined supramolecular environment is complementary to the geometry of classic octahedral complexes [M(XY)₆] with six diatomic ligands. Very strong binding of [Pt(CN)₆]^2? to the cage was observed, with the structure of the host–guest complex {[Pt(CN)₆]@Pd₂L₄} supported by NMR spectroscopy, MS, and X‐ray data. The self‐assembled shell imprints its geometry on the encapsulated guest, and desymmetrization of the octahedral platinum species by the influence of the D_4h‐symmetric second coordination sphere was evidenced by IR spectroscopy. [Fe(CN)₆]^3? and square‐planar [Pt(CN)₄]^2? were strongly bound. Smaller octahedral anions such as [SiF₆]^2?, neutral carbonyl complexes ([M(CO)₆]; M=Cr, Mo, W) and the linear [Ag(CN)₂]^? anion were only weakly bound, showing that both size and charge match are key factors for high‐affinity binding.     

Investigation of the Catalytic Activity of a 2‐Phenylidenepyridine Palladium(II) Complex Bearing 4,5‐Dicyano‐1,3‐bis(mesityl)imidazol‐2‐ylidene in the Mizoroki‐Heck Reaction

The phenylidenepyridine (ppy) palladacycles [PdCl(ppy)(IMes)] ( 4 ) [IMes = 1,3‐bis(mesityl)imidazol‐2‐ylidene] and [PdCl(ppy){(CN)₂IMes}] ( 6 ) [(CN)₂IMes = 4,5‐dicyano‐1,3‐bis(mesityl)imidazol‐2‐ylidene] were prepared by facile two step syntheses, starting with the reaction of palladium(II) chloride with 2‐phenylpyridine followed by subsequent addition of the NHC ligand to the precatalyst precursor [PdCl(ppy)]₂. Suitable crystals for the X‐ray analysis of the complexes 4 and 6 were obtained. It was shown that 6 has a shorter NHC‐palladium bond than the IMes complex 4 . The difference of the palladium carbene bond lengths based on the higher π‐acceptor strength of (CN)₂IMes in comparison to IMes. Thus, (CN)₂IMes should stabilize the catalytically active central palladium atom better than IMes. As a measure for the π‐acceptor strength of (CN)₂IMes compared to IMes, the selone (CN)₂IMes · Se ( 7 ) was prepared and characterized by ⁷⁷Se‐NMR spectroscopy. The π‐acceptor strength of 7 was illuminated by the shift of its ⁷⁷Se‐NMR signal. The ⁷⁷Se‐NMR signal of 7 was shifted to much higher frequencies than the ⁷⁷Se‐NMR signal of IMes · Se. Catalytic experiments using the Mizoroki‐Heck reaction of aryl chlorides with n‐butyl acrylate showed that 6 is the superior performer in comparison to 4 . Using complex 6 , an extensive substrate screening of 26 different aryl bromides with n‐butyl acrylate was performed. Complex 6 is a suitable precatalyst for para‐substituted aryl bromides. The catalytically active species was identified by mercury poisoning experiments to be palladium nanoparticles.     

The HNO donor ability of hydroxamic acids upon oxidation with cyanoferrates(III)

The hydroxamic acids (RC(O)NHOH, HA) exhibit diverse biological activity, including hypotensive properties associated with formation of nitroxyl (HNO) or nitric oxide (NO). Oxidation of two HAs, benzohydroxamic and acetohydroxamic acids (BHA, AHA) by [Fe(CN)₅NH₃]^2? or [Fe(CN)₆]^3? was analyzed by spectroscopic, mass spectrometric techniques, and flow EPR measurements. Mixing BHA with both Fe(III) reactants at pH 11 allowed detecting the hydroxamate radical, (C₆H₅)C(O)NO˙^?, as a one-electron oxidation product, as well as N₂O as a final product. Successive UV–vis spectra of mixtures containing [Fe(CN)₅NH₃]^2? (though not [Fe(CN)₆]^3?) at pH 11 and 7 revealed an intermediate acylnitroso-complex, [Fe(CN)₅NOC(O)(C₆H₅)]^3? (λ_max, 465 nm, very stable at pH 7), formed through ligand interchange in the initially formed reduction product, [Fe(CN)₅NH₃]^3?, and characterized by FTIR spectra through the stretching vibrations ν_(CN), ν_(CO), and ν_(NO). Free acylnitroso derivatives, formed by alternative reaction paths of the hydroxamate radicals, hydrolyze forming RC(O)OH and HNO, postulated as precursor of N₂O. Minor quantities of NO are formed only with an excess of oxidant. The intermediacy of HNO was confirmed through its identification as [Fe(CN)₅(HNO)]^3? (λ_max, 445 nm) as a result of hydrolysis of [Fe(CN)₅(NOC(O)(C₆H₅)]^3? at pH 11. The results demonstrate that hydroxamic acids behave predominantly as HNO donors.     

Synthese und spektroskopische Charakterisierung von [Rh(SeCN)6]3– und trans‐[Rh(CN)2(SeCN)4]3–, Kristallstruktur von (Me4N)3[Rh(SeCN)6]

Synthesis and Spectroscopic Characterization of [Rh(SeCN)₆]^3– and trans ‐[Rh(CN)₂(SeCN)₄]^3–, Crystal Structure of (Me₄N)₃[Rh(SeCN)₆] Treatment of RhCl₃ with KSeCN in acetone yields a mixture of selenocyanato‐rhodates(III), from which [Rh(SeCN)₆]^3– and trans‐[Rh(CN)₂(SeCN)₄]^3– have been isolated by ion exchange chromatography on diethylaminoethyl cellulose. The X‐ray structure determination on a single crystal of (Me₄N)₃[Rh(SeCN)₆] (trigonal, space group R3, a = 14.997(2), c = 24.437(3) Å, Z = 6) reveals, that the compound crystallizes isotypically to (Me₄N)₃[Ir(SCN)₆]. The exclusively via Se coordinated selenocyanato ligands are bonded with the average Rh–Se distance of 2.490 Å and the Rh–Se–C angle of 104.6°. In the low temperature IR and Raman spectra the metal ligand stretching modes ν(RhSe) of (n‐Bu₄N)₃[Rh(SeCN)₆] ( 1 ) and trans‐(n‐Bu₄N)₃[Rh(CN)₂(SeCN)₄] ( 2 ) are in the range of 170–250 cm^–1. In 2 ν_as(CRhC) is observed at 479 cm^–1. The vibrational spectra are assigned by normal coordinate analysis based on the molecular parameters of the X‐ray determination. The valence force constants are f_d(RhSe) = 1.08 ( 1 ), 1.10 ( 2 ) and f_d(RhC) = 3.14 mdyn/Å ( 2 ). f_d(RhS) = 1.32 mdyn/Å is determined for [Rh(SCN)₆]^3–, which has not been calculated so far. The ¹⁰³Rh NMR resonances are 2287 ( 1 ), 1680 ppm ( 2 ) and the ⁷⁷Se NMR resonances are –32.7 ( 1 ) and –110.7 ppm ( 2 ). The Rh–C bonding of the cyano ligand in 2 is confirmed by a dublett in the ¹³C NMR spectrum at 136.3 ppm.     

Characterising lone-pair activity of lead(II) by 207Pb solid-state NMR spectroscopy: coordination polymers of [N(CN)2]- and [Au(CN)2]- with terpyridine ancillary ligands

A series of lead(II) coordination polymers containing [N(CN)₂]^? (DCA) or [Au(CN)₂]^? bridging ligands and substituted terpyridine (terpy) ancillary ligands ([Pb(DCA)₂] ( 1 ), [Pb(terpy)(DCA)₂] ( 2 ), [Pb(terpy){Au(CN)₂}₂] ( 3 ), [Pb(4′‐chloro‐terpy){Au(CN)₂}₂] ( 4 ) and [Pb(4′‐bromo‐terpy)(μ‐OH₂)_0.5{Au(CN)₂}₂] ( 5 )) was spectroscopically examined by solid‐state ²⁰⁷Pb MAS NMR spectroscopy in order to characterise the structural and electronic changes associated with lead(II) lone‐pair activity. Two new compounds, 2 and [Pb(4′‐hydroxy‐terpy){Au(CN)₂}₂] ( 6 ), were prepared and structurally characterised. The series displays contrasting coordination environments, bridging ligands with differing basicities and structural and electronic effects that occur with various substitutions on the terpyridine ligand (for the [Au(CN)₂]^? polymers). ²⁰⁷Pb NMR spectra show an increase in both isotropic chemical shift and span (Ω) with increasing ligand basicity (from δ_iso=?3090 ppm and Ω=389 ppm for 1 (the least basic) to δ_iso=?1553 ppm and Ω=2238 ppm for 3 (the most basic)). The trends observed in ²⁰⁷Pb NMR data correlate with the coordination sphere anisotropy through comparison and quantification of the Pb? N bond lengths about the lead centre. Density functional theory calculations confirm that the more basic ligands result in greater p‐orbital character and show a strong correlation to the ²⁰⁷Pb NMR chemical shift parameters. Preliminary trends suggest that ²⁰⁷Pb NMR chemical shift anisotropy relates to the measured birefringence, given the established correlations with structure and lone‐pair activity.     

Pseudohalogen Chemistry in Ionic Liquids with Non-innocent Cations and Anions

Within the second funding period of the SPP 1708 “Material Synthesis near Room Temperature”,which started in 2017, we were able to synthesize novel anionic species utilizing Ionic Liquids (ILs) both, as reaction media and reactant. ILs, bearing the decomposable and non-innocent methyl carbonate anion [CO₃Me]⁻, served as starting material and enabled facile access to pseudohalide salts by reaction with Me₃Si−X (X=CN, N₃, OCN, SCN). Starting with the synthesized Room temperature Ionic Liquid (RT-IL) [nBu₃MeN][B(OMe)₃(CN)], we were able to crystallize the double salt [nBu₃MeN]₂[B(OMe)₃(CN)](CN). Furthermore, we studied the reaction of [WCC]SCN and [WCC]CN (WCC=weakly coordinating cation) with their corresponding protic acids HX (X=SCN, CN), which resulted in formation of [H(NCS)₂]⁻ and the temperature labile solvate anions [CN(HCN)_n]⁻ (n=2, 3). In addition, the highly labile anionic HCN solvates were obtained from [PPN]X ([PPN]=μ-nitridobis(triphenylphosphonium), X=N₃, OCN, SCN and OCP) and HCN. Crystals of [PPN][X(HCN)₃] (X=N₃, OCN) and [PPN][SCN(HCN)₂] were obtained when the crystallization was carried out at low temperatures. Interestingly, reaction of [PPN]OCP with HCN was noticed, which led to the formation of [P(CN)₂]⁻, crystallizing as HCN disolvate [PPN][P(CN⋅HCN)₂]. Furthermore, we were able to isolate the novel cyanido(halido) silicate dianions of the type [SiCl_0.78(CN)_5.22]²⁻ and [SiF(CN)₅]²⁻ and the hexa-substituted [Si(CN)₆]²⁻ by temperature controlled halide/cyanide exchange reactions. By facile neutralization reactions with the non-innocent cation of [Et₃HN]₂[Si(CN)₆] with MOH (M=Li, K), Li₂[Si(CN)₆] ⋅ 2 H₂O and K₂[Si(CN)₆] were obtained, which form three dimensional coordination polymers. From salt metathesis processes of M₂[Si(CN)₆] with different imidazolium bromides, we were able to isolate new imidazolium salts and the ionic liquid [BMIm]₂[Si(CN)₆]. When reacting [Mes(nBu)Im]₂[Si(CN)₆] with an excess of the strong Lewis acid B(C₆F₅)₃, the voluminous adduct anion {Si[CN⋅B(C₆F₅)₃]₆}²⁻ was obtained.     

Spectroscopic Evidence of in situ Formation of a Novel Tetrakis(Tetrazolato)Iron Compound

In an attempt to synthesize the complex [Fe(CN)₅(N₂)]^3- by reaction of Na[Fe(CN)₅(NO)]·2H₂O with azide followed by treatment with NO[SbCl₆], a similar method to that used by Feltham to obtain trans-[RuCl(N₂)(das)₂]Cl₂ from trans-[RuCl(NO)(das)₂]Cl₂, we found spectroscopic evidence that excess azide reacts with the CN^- ligands to generate tetrazolato groups C-coordinated to Fe. Initial results suggest that the obtained compound is sodium azidotris(2H-tetrazolato)(5H-tetrazolato)iron(0). The spectroscopic evidence also indicates that these heterocycles are destroyed by reaction with NO[SbCl₆], and the CN^- groups are regenerated. Here we present the characterization of these complexes by IR, ¹³C NMR, conductivity measurements, elemental analysis and magnetic susceptibility.     

Zur Charakterisierung von 1,1,2,3,3-Pentacyanopropenid als Komplexligand in ein- und zweizähniger Funktion. Darstellung von Komplexen des Typs [MX(PPh3)n] (M = CuI,AgI; X = NCC{C(CN)2}2; n = 2, 3)

Pseudoelement Compounds. XII. [1] On the Characterization of 1,1,2,3,3-Pentacyanopropenide in Unidentate and Bidentate Function. Syntheses of Complexes of the Type [MX(PPh₃)_n] (M = Cu^I, Ag^I; X = NCC{C(CN)₂}₂; n = 2, 3) 1,1,2,3,3-Pentacyanopropenide is characterized as unidentate and bidentate ligand. For that reason compounds of the types [MX(PPh₃)₃] ( 6 ) and [MX(PPh₃)₂]₂ ( 8 ) (M = Cu^I, Ag^I) are synthesized. In the complexes 6 the ionic ligand is coordinated unidentately through an end-on nitrile group of a C(CN)₂ unit and in the dimeric complexes 8 bidentately bridging through the N atoms of a C(CN)₂ moiety too. The compounds are characterized by ¹³C NMR, ³¹P NMR and IR spectroscopy. The crystal structure of [AgX(PPh₃)₃] is presented and the structural parameters of the anion in this complex and in [CuX(PPh₃)₂]₂ [X = NCC{C(CN)₂}₂] are compared.     

Synthesis and Characterization of β‐Diketiminate Aluminum Compounds and Their Use in the Ring‐Opening Polymerization of ε‐Caprolactone

Four aluminum alkyl compounds, [CH{(CH₃)CN‐2,4,6‐MeC₆H₂}₂AlMe₂] ( 1 ), [CH{(CH₃)CN‐2,4,6‐MeC₆H₂}₂AlEt₂] ( 2 ), [CH{(CH₃)CN‐2‐iPrC₆H₄}₂AlMe₂] ( 3 ), and [CH{(CH₃)CN‐2‐iPrC₆H₄}₂AlEt₂] ( 4 ), bearing β‐diketiminate ligands [CH{(Me)CN‐2,4,6‐MeC₆H₂}]₂ (L¹H) and [CH{(Me)CN‐2‐ⁱPrC₆H₄}]₂ (L²H) were obtained from the reactions of trimethylaluminum, triethylaluminum with the corresponding β‐diketiminate, respectively. All compounds were characterized by ¹H NMR and ¹³C NMR spectroscopy, single‐crystal X‐ray structural analysis, and elemental analysis. Compounds 1 – 4 were found to catalyze the ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) with good activity.     

Cyanidosilicates—Synthesis and Structure

Starting from fluoridosilicate precursors in neat cyanotrimethylsilane, Me₃Si?CN, a series of different ammonium salts [R₃NMe]⁺ (R=Et, ⁿPr, ⁿBu) with the novel [SiF(CN)₅]^2? and [Si(CN)₆]^2? dianions was synthesized in facile, temperature controlled F^?/CN^? exchange reactions. Utilizing decomposable, non‐innocent cations, such as [R₃NH]⁺, it was possible to generate metal salts of the type M₂[Si(CN)₆] (M⁺=Li⁺, K⁺) via neutralization reactions with the corresponding metal hydroxides. The ionic liquid [BMIm]₂[Si(CN)₆] (m.p.=72 °C, BMIm=1‐butyl‐3‐methylimidazolium) was obtained by a salt metathesis reaction. All the synthesized salts could be isolated in good yields and were fully characterized.     

Pseudo Halide Chemistry in Ionic Liquids with Decomposable Anions

Several pseudohalide containing ionic liquids with quarternary ammonium counter cations of the general formula [R₃MeN]X [R = ethyl ( 1X ), n‐butyl ( 2X ) with X^– = CN^–, N₃^–, OCN^–, and SCN^–] were synthesized by decomposition of the corresponding trialkylammonium methylcarbonate in the reaction with Me₃Si–X. We also treated 2CN with OP(OMe)₃, yielding [nBu₃MeN][O₂P(OMe)₂] and acetonitrile (Me‐CN). The double salt [nBu₃MeN]₂{[B(OMe)₃(CN)](CN)} was obtained from the reaction of 2CN with B(OMe)₃, featuring the formation of the monocyanotrimethoxyborate anion, [B(OMe)₃(CN)]^–, co‐crystallized with [nBu₃MeN]CN. [nBu₃MeN]₂{[B(OMe)₃(CN)](CN)} was fully characterized including structure elucidation.     

Structure and in vitro antifungal activity of [2,6‐bis(dimethylaminomethyl)phenyl]diphenyltin(IV) compounds

A set of seven [2,6‐bis(dimethylaminomethyl)phenyl]diphenyltin(IV) ({[(CH₃)₂NCH₂]₂(C₆H₃)}­(C₆H₅)₂Sn⁺X^?) ionic organotin(IV) compounds (X = Br, NO₃, CN, SCN, SeCN, BF₄ and PF₆) has been prepared and characterized by electrospray ionization mass spectrometry, ¹H NMR spectroscopy in CDCl₃,¹¹⁹Sn NMR in CDCl₃ and DMSO‐d₆ solution, as well as by ¹³C and ¹¹⁹Sn CP/MAS NMR spectroscopy and X‐ray diffraction techniques in the solid state. The in vitro antifungal activity of these water‐soluble ionic organotin(IV) compounds was compared with starting compounds and the antifungal drugs currently in clinical use. Copyright © 2002 John Wiley & Sons, Ltd.     

Tetracyanido(difluorido)phosphates M+[PF2(CN)4]−

The systematic study of the reaction of M[PF₆] salts and Me₃SiCN led to a synthetic method for the synthesis and isolation of a series of salts containing the unprecedented [PF₂(CN)₄]^? ion in good yields. The reaction temperature, pressure, and stoichiometry were optimized. The crystal structures of M[PF₂(CN)₄] (M=[nBu₄N]⁺, Ag⁺, K⁺, Li⁺, H₅O₂⁺) were determined. X‐ray crystallography showed the exclusive formation of the cis isomer in accord with ³¹P and ¹⁹F solution NMR spectroscopy data. Starting with the K[PF₂(CN)₄] the room temperature ionic liquid EMIm[PF₂(CN)₄] was prepared exhibiting a rather low viscosity.     

Electronic Structure and Molecular Properties of the Mixed Rhenium–Molybdenum [Re6−x Mo x S8(CN)6]q−, (x = 0 to 6) Clusters

Relativistic density functional calculations including scalar and spin-orbit effects via the ZORA approximation and including solvent effects were carried out on the [Re₆S₈(CN)₆]⁴⁻, [Re₅MoS₈(CN)₆]⁵⁻, [Re₄Mo₂S₈(CN)₆]⁵⁻, [Re₃Mo₃S₈(CN)₆]⁵⁻, [Re₂Mo₄S₈(CN)₆]⁵⁻, [ReMo₅S₈(CN)₆]⁵⁻ and [Mo₆S₈(CN)₆]⁶⁻ clusters. By increasing the replacement of each Re atom with Mo atoms we find that for x > 2 the HOMO–LUMO gap decreases significantly. The calculated gap of the [Re₃Mo₃S₈(CN)₆]⁵⁻, [Re₂Mo₄S₈(CN)₆]⁵⁻ and [ReMo₅S₈(CN)₆]⁵⁻ clusters is similar to the calculated and observed gap of the superconducting PbMo₆S₈ Chevrel phases. The current calculations also indicates that the electronic similarities of the lowest excited states of the semiconducting 24e [Re₅MoS₈(CN)₆]⁵⁻ and 23e [Re₄Mo₂S₈(CN)₆]⁵⁻ clusters with the strongly luminescent 24e [Re₆S₈(CN)₆]⁴⁻ cluster, suggest that these mixed metal clusters might be luminescent.     

M[B(CN)4]2: Zwei neue Tetracyanoborate mit zweiwertigen Kationen (M = Zn,Cu)

M[B(CN)₄]₂: Two new Tetracyanoborate Compounds with divalent Cations (M = Zn, Cu) The reaction of ZnO or CuO with [H₃O][B(CN)₄] in aqueous solution yielded single crystals of Zn[B(CN)₄]₂ and Cu[B(CN)₄]₂, respectively. The compounds were characterized by single‐crystal X‐ray diffraction. Zn[B(CN)₄]₂ ( (no. 164), a = b = 7.5092(9) Å, c = 6.0159(6) Å, Z = 1) crystallizes isotypic with Hg[B(CN)₄]₂. The structure of Cu[B(CN)₄]₂ (C2/m (no. 12), a = 13.185(3) Å, b = 7.2919(9) Å, c = 6.029(1) Å, β = 93.02(2)°, Z = 2) can be considered as a super‐structure, resulting from Jahn‐Teller distortion of the Cu²⁺ ions. Magnetic measurements were performed for the copper compound. Vibrational spectra and thermal stabilities were compared with the known mercury(II) tetracyanoborate.     

Free electron model in cluster structure theory. Electronic structures of [Mo6S8(CN)6]6?, [Mo6Se8(CN)6]6?, [Re6S8(CN)6]4?, and Rh6(CO)16 clusters

The results of quantum chemical calculations of the electronic structure and geometry of octahedral clusters [Mo₆S₈(CN)₆]⁶⁻, [Mo₆Se₈(CN)₆]⁶⁻, [Re₆S₈(CN)₆]⁴⁻, and Rh₆(CO)₁₆ by the ab initio SCF (RHF) and DFT (B3LYP) methods with various basis sets are presented. The electronic states of the clusters under study in ideal spherically symmetric potential were classified in the orbital quantum number l (1s, 1p, 1d, 1f, 1g, 1h, 1i), l = 0–6. In real crystal field with O_h symmetry these states are split. The calculated new electronic states were matched to the irreducible representations of the point symmetry group O_h. The polarizabilities of the compounds considered are 55–65 ų. A new model for the electronic structure of octahedral clusters containing M₆ groups was proposed. The model is based on the idea of free electrons moving in spherically symmetric potential field. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2617–2624, December, 2005.     

SIMULTANEOUS REPLACEMENTS OF TRIETHYL PHOSPHINE AND TETRAACETYL THIOGLUCOSE LIGANDS FROM AURANOFIN (AN ANTIARTHRITIC DRUG) WITH SELENOCYANATE 13C and 31P NMR STUDIES

Abstract

The interaction of SeCN^? with a new gold-based antiarthritic drug auranofin (Et₃PAuSATg, where SATg^? = 2, 3, 4, 6-tetra-O-acetyl-l-thio-β-D-glucopyranosato-S) in aqueous methanol has been studied by ¹³C and ³¹P NMR spectroscopy. It is observed that SeCN^?releases bom ligands (i. e., SATg^? and Et₃P) to form [ATgS-Au-CN]^? and [Et₃P-Au-SeCN]. These newly generated species undergo further disproportionation and decomposition to generate species such as [(Et₃P)₂Au]⁺, [Au(CN)₂]^?, Et₃PO and metallic selenium. The formation of [(Et₃P)₂Au]⁺ and [Au(CN)₂]^? is found to be much faster for Et₃PAuNO₃ than for Et₃PAuSATg when reacted wim SeCN^?. Exchange between unlabelled CN^? of Au(CN)₂ ^? and labelled Se¹³CN^? was observed without selenium being precipitated from Se¹³CN^?.     

Reaction of [CpRu(CH3CN)3]PF6 with bidentate ligands: structural characterization of [{CpRu(CH3CN)2}2(μ-η-dppe)](PF6)2 [dppe=1,2-bis(diphenylphosphino)ethane]

The reaction of [CpRu(CH₃CN)₃]PF₆ with the bidentate ligands L-L=1,2-bis(diphenylphosphino)ethane, dppe, and (1-diphenylarsino-2-diphenylphosphino)ethane, dpadppe, affords mononuclear or dinuclear complexes of formula [CpRu(η²-L-L)(CH₃CN)]PF₆, [{CpRu(CH₃CN)₂}₂(μ-η^1:1-L-L)](PF₆)₂ and [{CpRu(CH₃CN)}₂(μ-η^1:1-L-L)₂](PF₆)₂ (L-L=dppe, dpadppe). All of the compounds are characterized by microanalysis and NMR [¹H and ³¹P{¹H}] spectroscopy. The crystal structure of [{CpRu(CH₃CN)₂}₂(μ-η^1:1-dppe)](PF₆)₂ has been determined by X-ray diffraction analysis. The complex exhibits a dppe ligand bridging two CpRu(CH₃CN)₂ fragments.     

Zusammensetzung und strukturelle Eigenschaften des „zweiwertigen”︁ Kobaltcyanids

The products obtained by mixing aqueous solutions of cobalt (II) chloride and potassium or hydrogen cyanide are nonstoichiometric compounds Co(CN)_x, yH₂O whith x between 2.2 and 2.4 and y between 1.75 and 2.15. They have a cubic face-centered unit cell with a = 10.20 ± 0.02 Å and Z between 6.8 and 7.1 (Z = number of units Co (CN)_x yH₂O per cell). Infrared spectra show that there is zeolitic as well as coordinated water present. The coordination units derived from reflectance spectra in the ultraviolet and visible region are (Co^III)C₆ and Co^IIN_6-xO_x. There exists a close structural relationship between Co(CN)_x, yH₂O and the stoichiometric compound Co₃[Co(CN)₆]₂, zH₂O. Comparison of calculated with experimental density shows that there must be holes in the threedimensional Co? C? N? Co-framework, which can be occupied by water molecules.