Cobalt(III) Metallacryptates and Their Guest Cation-Exchange in Solution Monitored by Co NMR.

One-pot reactions of the catechol-scaffolding aroylbis(,-diethylthiourea) HL with mixtures of CoCl and MCl (M = Cs, Rb, K, Tl, or NH) or with a Co(NO)/TlNO mixture lead to the self-assembly of a series of cationic Co(III) metallacryptates of the general formula [M ⊂ {Co(L)}] (M = Cs, Rb, K, Tl, or NH). Crystalline PF salts were obtained after workup with (-BuN)(PF), and the single-crystal structures of all five metallacryptates have been determined. Depending on the nature of the guest cations, the directional interactions between guest cations and the metallacryptand {Co(L)} are either weak coordination contacts or hydrogen bonds.

Reversible photo-isomerization of cis-[Pd(L-κS,O)] (HL = N,N-diethyl-N'-1-naphthoylthiourea) to trans-[Pd(L-κS,O)] and the unprecedented formation of trans-[Pd(L-κS,N)] in solution.

Upon ex situ UV-visible light irradiation, complex cis-bis(N,N-diethyl-N'-naphthoylthioureato)-palladium(ii), cis-[Pd(L-κS,O)2], undergoes isomerization in acetonitrile-d3 and chloroform-d to yield trans-[Pd(L-κS,O)2] which then rearranges thermally to novel trans-[Pd(L-κS,N)2] prior to reverting thermally to the cis isomer in the absence of light. The thermal isomerization rate is highly solvent dependent and harnessed to enable each of these three geometric isomers to be isolated and characterized by 1H NMR spectroscopy, X-ray crystallography, melting point and thermal analysis. The formation of the trans-[Pd(L-κS,N)2] isomer as part of this isomerization has only been observed with the sterically demanding cis-bis(N,N-diethyl-N'-(naphthoylthioureato)palladium(ii) precursor based on our knowledge to date.

Pt NMR and Molecular Dynamics Simulation Study of the Solvation of [PtCl] in Water-Methanol and Water-Dimethoxyethane Binary Mixtures.

The experimental Pt NMR chemical shift, δ(Pt), of the [PtCl] anion dissolved in binary mixtures of water and a fully miscible organic solvent is extremely sensitive to the composition of the mixture at room temperature. Significantly nonlinear δ(Pt) trends as a function of solvent composition are observed in mixtures of water-methanol, or ethylene glycol, 2-methoxyethanol, and 1,2-dimethoxyethane (DME). The extent of the deviation from linearity of the δ(Pt) trend depends strongly on the nature of the organic component in these solutions, which broadly suggests preferential solvation of the [PtCl] anion by the organic molecule.

Intrinsic Cl and O isotope shifts in Pt and Rh NMR of purely inorganic Pt and Rh complexes as unique spectroscopic fingerprints for unambiguous assignment of structure.

Well-resolved intrinsic ΔM(Cl) and ΔM(O) isotope shifts (where M = Pt or Rh) are visible in the Pt NMR peak profiles of relatively kinetically inert [PtCl(HO)] (n = 1-6) complexes, their corresponding hydroxido [PtCl(OH)] (n = 1-5/6) anions, and [RhCl(HO)] (n = 3-6) complexes in aqueous solutions at ca. 293 K. Although some such isotope effects have been previously reported, there are very limited published data in the open literature, and the first systematic studies of such intrinsic ΔM(Cl) and ΔM(O) isotope effects are reviewed in this perspective.

A DFT study to unravel the ligand exchange kinetics and thermodynamics of Os(VIII) oxo/hydroxido/aqua complexes in aqueous matrices.

The Os(VIII) oxo/hydroxido complexes that are abundant in mild to relatively concentrated basic aqueous solutions are Os(VIII)O4, [Os(VIII)O4(OH)](-) and two cis-[Os(VIII)O4(OH)2](2-) species. Os(VIII) complexes that contain water ligands are thermodynamically unfavoured w.r.

Isotope effects in (195)Pt NMR spectroscopy: unique (35/37)Cl- and (16/18)O-resolved "fingerprints" for all [PtCl6-n(OH)n](2-) (n = 1-5) anions in an alkaline solution and the implications of the trans influence.

A detailed analysis of the intrinsic (1)Δ(195)Pt((37/35)Cl) and (1)Δ(195)Pt((18/16)O) isotope 128.8 MHz (195)Pt NMR profiles of the series of kinetically inert [PtCl6-n(OH)n](2-) (n = 1-5) anions generated in strongly alkaline aqueous solutions shows that each (195)Pt NMR resonance of the [Pt(35/37)Cl6-n((16/18)OH)n](2-) (n = 1-5) anions is resolved only into [(6 - n) + 1 for n = 1-5] (35/37)Cl isotopologues at 293 K. Evidently, the greater trans influence of the hydroxido ligand in the order OH(-) > Cl(-) > H2O in [PtCl6-n(OH)n](2-) (n = 1-5) complexes results in somewhat longer Pt-Cl bond displacements trans to the hydroxido ligands, resulting in the absence of isotopomer effects in the [PtCl6-n(OH)n](2-) (n = 1-5) anions in contrast to that observed in the corresponding [PtCl6-n(H2O)n]((2-n)-) (n = 1-5) complexes.

Mechanism of tetrachloroplatinate(II) oxidation by hydrogen peroxide in hydrochloric acid solution.

Oxidation of tetrachloroplatinate(II) by hydrogen peroxide in hydrochloric acid was studied by UV-Vis spectrophotometry. Oxidation takes place via two parallel reactions with hypochlorous acid and hydrogen peroxide, respectively, according to the overall rate law d[Pt(IV)]/dt = (k(0) + k(H2O2)[Pt(II)])[H2O2]. For oxidation of [PtCl4](2-) at relatively low concentrations, [PtCl4](2-) ≪ 0.

Probing isotope shifts in 103Rh and 195Pt NMR spectra with density functional theory.

Zero-point vibrationally averaged (rg(0)) structures were computed at the PBE0/SDD/6-31G* level for the [Pt(35)Cln(37)Cl5-n(H2(18)O)](-) (n = 0-5), cis-Pt(35)Cln(37)Cl4-n(H2(18)O)(H2(16)O) (n = 0-4), fac-[Pt(35)Cln(37)Cl3-n(H2(18)O)(H2(16)O)2](+) (n = 0-3), [Pt(35)Cln(37)Cl5-n((16/18)OH)](2-) (n = 0-5), cis-[Pt(35)Cln(37)Cl4-n((16/18)OH)2](2-) (n = 0-4), fac-[Pt(35)Cln(37)Cl3-n((16/18)OH)3](2-) (n = 0-3), cis-[Pt(35)Cln(37)Cl2-n((16/18)OH)4](2-) (n = 0-2), [Pt(35)Cln(37)Cl1-n((16/18)OH)5](2-) (n = 0-1), [Rh(35)Cln(37)Cl5-n(H2O)](2-) (n = 0-5), cis-[Rh(35)Cln(37)Cl4-n(H2O)2](-) (n = 0-4), and fac-Rh(35)Cln(37)Cl3-n(H2O)3 (n = 0-3) isotopologues and isotopomers. Magnetic shielding constants, computed at the ZORA-SO/PW91/QZ4P/TZ2P level, were used to evaluate the corresponding (35/37)Cl isotope shifts on the (195)Pt and (103)Rh NMR spectra, which are known experimentally. While the observed effects are reproduced reasonably well computationally in terms of qualitative trends and the overall order of magnitude (ca.

Cation-π induced aggregation of water-soluble [Pt(II)(diimine)(L(n)-S,O)]+ complexes studied by 1H DOSY NMR and TEM: from 'dimer aggregates' in acetonitrile to nano-aggregates ('metallogels') in water.

(1)H NMR chemical shift concentration dependence as well as the diffusion coefficients from DOSY NMR of mixed ligand [Pt(II)(1,10-phenanthroline)(N-pyrrolidyl-N-(2,2-dimethylpropanoyl)thiourea)]Cl ([Pt(II)(phen)(L(1)-S,O)]Cl) dissolved in mixtures of acetonitrile-water in the range 0-30% (v/v) D(2)O-CD(3)CN shows that the complex cation (M(+) = [Pt(II)(phen)(L(1)-S,O)](+)) aggregates to form dimers, 2M(+) ⇌ {M(+)}(2), with association constants ranging from K(D)(CD(3)CN) = 17 ± 2 M(-1) to K(D)(30% (v/v) D(2)O-CD(3)CN) = 71 ± 8 M(-1) at 299.3 K, presumably via non-covalent cation-π interactions. Experimental data are consistent with an 'offset' face-to-face cation-π stacking arrangement of the planar cation.

(35/37)Cl and (16/18)O isotope resolved 195Pt NMR: unique spectroscopic 'fingerprints' for unambiguous speciation of [PtCl(n)(H2O)(6-n)](4-n) (n = 2-5) complexes in an acidic aqueous solution.

At high magnetic fields the 128.8 MHz (195)Pt NMR of all the species in the series [PtCl(n)(H(2)O)(6-n)](4-n) (n = 2-6) display unique (35/37)Cl isotope effects resulting in a unique 'fine-structure' of each individual resonance, which constitutes an unambiguous spectroscopic 'fingerprint' characteristic of the structure of the octahedral platinum(IV) complex, provided (195)Pt NMR are recorded at optimum magnetic field homogeneity and carefully controlled temperature (293 ± 0.1 K).

35Cl/37Cl isotope effects in 103Rh NMR of [RhCl(n)(H2O)(6-n)](3-n) complex anions in hydrochloric acid solution as a unique 'NMR finger-print' for unambiguous speciation.

A detailed analysis of the (35)Cl/(37)Cl isotope effects observed in the 19.11 MHz (103)Rh NMR resonances of [RhCl(n)(H(2)O)(6-n)](3-n) complexes (n=3-6) in acidic solution at 292.1K, shows that the 'fine structure' of each (103)Rh resonance can be understood in terms of the unique isotopologue and in certain instances the isotopomer distribution in each complex.

On the Origin of (35/37)Cl Isotope Effects on (195)Pt NMR Chemical Shifts. A Density Functional Study.

Zero-point vibrationally averaged (rg(0)) structures were computed at the PBE0/SDD/6-31G* level for [Pt(35)Cl6](2-) and [Pt(37)Cl6](2-), for the [Pt(35)Cln(37)Cl5-n(H2O)](-) (n = 0-5), cis-Pt(35)Cln(37)Cl(4-n)(H2O)2 (n = 0-4), and fac-[Pt(35)Cln(37)Cl(3-n)(H2O)3](+) (n = 0-3) isotopologues and isotopomers. Magnetic (195)Pt shielding constants, computed at the ZORA-SO/PW91/QZ4P/TZ2P level, were used to evaluate the corresponding (35/37)Cl isotope shifts in the experimental (195)Pt NMR spectra. While the observed effects are reproduced reasonably well computationally in terms of qualitative trends and the overall order of magnitude (ca.

A robust method for speciation, separation and photometric characterization of all [PtCl(6-n)Br(n)]2- (n=0-6) and [PtCl(4-n)Br(n)]2- (n=0-4) complex anions by means of ion-pairing RP-HPLC coupled to ICP-MS/OES, validated by high resolution 195Pt NMR spectroscopy.

A robust reversed phase ion-pairing RP-HPLC method has been developed for the unambiguous speciation and quantification of all possible homoleptic and heteroleptic octahedral platinum(IV) [PtCl(6-n)Br(n)](2-) (n=0-6) as well as the corresponding platinum(II) [PtCl(4-n)Br(n)](2-) (n=0-4) complex anions using UV/Vis detection. High resolution (195)Pt NMR in more concentrated solutions of these Pt(II/IV) complexes (≥50 mM) served to validate the chromatographic peak assignments, particularly in the case of the possible stereoisomers of Pt(II/IV) complex anions. By means of IP-RP-HPLC coupled to ICP-MS or ICP-OES it is possible to accurately determine the relative concentrations of all possible Pt(II/IV) species in these solutions, which allows for the accurate determination of the photometric characteristics (λ(max) and ɛ) of all the species in this series, by recording of the UV/Vis absorption spectra of all eluted species, using photo-diode array, and quantification with ICP-MS or ICP-OES.

A kinetic and thermodynamic study of the unexpected comproportionation reaction between cis-[Os(VIII)O4(OH)2](2-) and trans-[Os(VI)O2(OH)4](2-) to form a postulated [Os(VII)O3(OH)3](2-) complex anion.

A kinetic study of [OsO(4)] reduction by aliphatic alcohols (MeOH and EtOH) was performed in a 2.0 M NaOH matrix at 298.1 K.

A comparison of experimental and DFT calculations of ¹⁹⁵Pt NMR shielding trends for [PtX(n)Y(6-n)](2-) (X, Y = Cl, Br, F and I) anions.

A comparison between experimental and calculated gas-phase as well as the conductor-like screening model DFT (195)Pt chemical shifts of a series of octahedral [PtX(6-n)Y(n)](2-) complexes for X = Cl, Br, F, I was carried out to assess the accuracy of computed NMR shielding and to gain insight into the dominant σ(dia), σ(para) and σ(SO) shielding contributions. The discrepancies between the experimental and the DFT-calculated (195)Pt chemical shifts vary for these complexes as a function of the coordinated halide ions, the largest being obtained for the fluorido-chlorido and fluorido-bromido complexes, while negligible discrepancies are found for the [PtCl(6-n)Br(n)](2-) series; the discrepancies are somewhat larger where a significant deviation from the ideal octahedral symmetry such as for the geometric cis/trans or fac/mer isomers of [PtF(6-n)Cl(n)](2-) and [PtF(6-n)Br(n)](2-) may be expected. The discrepancies generally increase in the order [PtCl(6-n)Br(n)](2-) < [PtBr(6-n)I(n)](2-) < [PtCl(6-n)I(n)](2-) < [PtF(6-n)Br(n)](2-) ≈ [PtF(6-n)Cl(n)](2-), and show a striking correlation with the increase in electronegativity difference Δχ between the two halide ligands (X(-) and Y(-)) bound to Pt(IV) for these anions: 0.

Separation and quantification of [RhCln(H2O)(6-n)](3-n) (n=0-6) complexes, including stereoisomers, by means of ion-pair HPLC-ICP-MS.

A hyphenated ion-pair (tetrabutylammonium chloride-TBACl) reversed phase (C(18)) HPLC-ICP-MS method (High Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectroscopy) for anionic Rh(III) aqua chlorido-complexes present in an HCl matrix has been developed. Under optimum chromatographic conditions it was possible to separate and quantify cationic Rh(III) complexes (eluted as a single band), [RhCl(3)(H(2)O)(3)], cis-[RhCl(4)(H(2)O)(2)](-), trans-[RhCl(4)(H(2)O)(2)](-) and [RhCl(n)(H(2)O)(6-n)](3-n) (n=5, 6) species. The [RhCl(n)(H(2)O)(6-n)](3-n) (n=5, 6) complex anions eluted as a single band due to the relatively fast aquation of [RhCl(6)](3-) in a 0.

A novel approach to the rapid assignment of (13)C NMR spectra of major components of vegetable oils such as avocado, mango kernel and macadamia nut oils.

Assignment of (13)C nuclear magnetic resonance (NMR) spectra of major fatty acid components of South African produced vegetable oils was attempted using a method in which the vegetable oil was spiked with a standard triacylglycerol. This proved to be inadequate and therefore a new rapid and potentially generic graphical linear correlation method is proposed for assignment of the (13)C NMR spectra of major fatty acid components of apricot kernel, avocado pear, grapeseed, macadamia nut, mango kernel and marula vegetable oils. In this graphical correlation method, chemical shifts of fatty acids present in a known standard triacylglycerol is plotted against the corresponding chemical shifts of fatty acids present in the vegetable oils.

(195)Pt NMR isotopologue and isotopomer distributions of [PtCl(n)(H(2)O)(6 - n)](4 - n) (n = 6,5,4) species as a fingerprint for unambiguous assignment of isotopic stereoisomers.

A detailed analysis of the (35)Cl/(37)Cl isotope shifts induced in the 128.8 MHz (195)Pt NMR resonances of [PtCl(n)(H(2)O)(6 - n)](4 - n) complexes (n = 6,5,4) in acidic solution at 293 K, shows that the unique isotopologue and isotopomer distribution displayed by the resolved (195)Pt resonances, serve as a fingerprint for the unambiguous identification and assignment of the isotopic stereoisomers of [PtCl(5)(H(2)O)](-) and cis/trans-[PtCl(4)(H(2)O)(2)].

Bipodal 1,1'-acyl-3,3,3',3'-tetraalkylbis(thiourea) ligands with flexible C3, C4 and C6 spacer groups.

In the structures of 3,3,3',3'-tetraethyl-1,1'-(propane-1,3-diyldicarbonyl)bis(thiourea), C(15)H(28)N(4)O(2)S(2), (I), 3,3,3',3'-tetraethyl-1,1'-(butane-1,4-diyldicarbonyl)bis(thiourea), C(16)H(30)N(4)O(2)S(2), (II), and 3,3,3',3'-tetrabutyl-1,1'-(hexane-1,6-diyldicarbonyl)bis(thiourea), C(26)H(50)N(4)O(2)S(2), (III), compound (I) displays resonance-assisted hydrogen bonding, (II) exhibits an inversion centre, and both (II) and (III) are characterized by intermolecular hydrogen bonds between the carbonyl O atoms and thioamide H atoms, leading to chains of hydrogen-bonded molecules throughout the structures. The accurate structural data for these molecules is expected to assist in molecular modelling and other studies currently in progress.

N-benzoyl-N',N'-dibutylselenourea and its palladium(II) complex.

The crystal and molecular structures of N-benzoyl-N',N'-dibutylselenourea (HL), C16H24N2OSe, and the corresponding complex bis(N-benzoyl-N',N'-dibutylselenoureato-kappa(2)Se,O)palladium(II), [Pd(C16H23N2OSe)2], are reported. The selenourea molecule is characterized by intermolecular hydrogen bonds between the selenoamidic H atom and the Se atom of a neighbouring molecule forming a dimer, presumably as a consequence of resonance-assisted hydrogen bonding or pi-bonding co-operativity. A second dimeric hydrogen bond is also described.

195Pt NMR chemical shift trend analysis as a method to assign new Pt(IV)-halohydroxo complexes.

A 195Pt NMR spectroscopy study of the speciation of [PtCl6]2-, [PtBr6]2-, and the mixed [PtCl6-mBrm]2- (m=0-6) anions in aqueous medium after hydroxide ion substitution of coordinated halide ions has been carried out under dynamic conditions. Of the 56 possible [PtCl6-m-nBrm(OH)n]2- (m, n=0-6) complex anions in solution under dynamic conditions, the relative chemical shifts delta(195Pt) of 52 observable species have been assigned, 33 of which had not been reported previously. The assignment of all these species including the possible stereoisomers is facilitated by systematic linear relationships between the delta(195Pt) increments resulting from substitutions of the halide ions by OH- ions.

195Pt NMR study of the speciation and preferential extraction of Pt(IV)-mixed halide complexes by diethylenetriamine-modified silica-based anion exchangers.

A detailed 195Pt NMR study of the distribution of Pt(IV) complex species resulting from the aquation of H2PtCl6, H2PtBr6, and mixtures of H2PtCl6/H2PtBr6 in water/dilute HClO4 has been carried out to obtain an understanding of the speciation in these solutions as relevant to the recovery of Pt(IV) complexes from process solutions. A species distribution plot of the [PtCl6]2-, [PtCl5(H2O)]-, and [PtCl4(H2O)2] shows that in equilibrated, relatively concentrated H2PtCl6 solutions ([Pt]t > 0.12 M), the [PtCl4(H2O)2] species is below the 195Pt NMR detection limit; for [Pt]t concentrations < 0.

195Pt NMR and DFT computational methods as tools towards the understanding of speciation and hydration/solvation of [PtX6]2- (X = Cl-, Br-) anions in solution.

195Pt NMR together with DFT calculations and MD simulations, offer a powerful toolkit with which to probe the hydration shells of the [PtCl6]2- anions, which may lead to a more profound understanding of the solute-solvent interactions of such complexes.