Zeise's Anion Research Articles

A Combined Gas‐Phase Photoelectron Spectroscopic and Theoretical Study of Zeise’s Anion and Its Bromine and Iodine Analogues

Shining light on Zeise: In a study of Zeise's anion, [PtCl(3)(C(2)H(4))](-), and its bromine and iodine analogues, electronic structure information for each species, derived from spectral features, is assigned through calculations at the coupled cluster level of theory. The calculations indicate that the electron binding energies decrease with halogen size and that there is a synergistic η(2) interaction between C(2)H(4) and the PtX(3)(-) anions.

Modulation of properties in analogues of Zeise's anion on changing the ligand trans to ethene. X-Ray crystal structures of trans-[PtCl2(OH)(η2-C2H4)]− and trans-[PtCl2(η1-CH2NO2)(η2-C2H4)

To get further insight in the reaction of nucleophilic substitution upon changing the ligand trans to a η(2)-olefin, the reactivity of some monoanionic platinum(II) complexes (trans-[PtCl(2)X(η(2)-C(2)H(4))](-), X = Cl(-), 1, OH(-), 2, and CH(2)NO(2)(-), 3) towards pyridines with different steric hindrance (py, 4-Mepy, and 2,6-Me(2)py) has been tested. All crystallographic (2 and 3 reported for the first time) and spectroscopic data are in accord with a platinum-olefin interaction decreasing in the order 2 > 1 > 3, paralleling the decreasing electronegativity of the donor atom (O > Cl > C). Not only the platinum-olefin bond but also the bond between platinum and the ligand trans to the olefin appear to be strongest in 2 (Pt-O distance at the lower limit for this type of bond). In the reaction with py, the ligand trans to the olefin is displaced in 1 and 2. Moreover the reaction is in equilibrium in the case of sterically hindered 2,6-Me(2)py, the equilibrium being shifted moderately or prevalently toward the reagents in the case of 1 and 2, respectively. In the case of 3, the reaction with pyridines leads to substitution of the olefin instead of the carbanion. This is in accord with the observation that carbanions strongly weaken the trans Pt-olefin bond.

New chemistry of olefin complexes of platinum(ii) unravelled by basic conditions: synthesis and properties of elusive cationic species

The evolution in basic medium ([RO-] = 1 M in methanol, R = H or Me) of five-coordinate platinum(II) compounds, [PtCl2(eta2-C2H4)(N-N)], 2a-c, (N-N = N,N,N',N'-tetramethyl-1,2-ethanediamine, a; 2,2'-bipyridyl, b; 1,10-phenanthroline, c) leads to the formation of [PtCl(eta1-CH2CH2-OCH3)(N-N)], 5a-c. The analogous compound 5d (N-N = 2,9-dimethyl-1,10-phenanthroline, d) can also be prepared, but not via transformation of the five-coordinate species 2d in basic medium where it is quite stable. 5d can instead be prepared by reaction of d with a strongly basic methanol solution of Zeise's anion [PtCl3(eta2-C2H4)](-), 1. In such a medium the di-anionic trans-[PtCl2(OR)(eta1-CH2CH2-OCH3)](2-) species (1") reacts with to form exclusively 5d. Hydrolysis of with acids bearing weakly coordinating anions leads to [PtCl(eta2-C2H4)(N-N)]+, 3a-c, as stable cations; upon the same treatment 5d does not generate 3d, but it reacts with HCl to give 2d in almost quantitative yield. Cationic complexes 3b, 3c, here reported for the first time, were reacted with some nucleophiles and their behaviour compared with that of the already known 3a. In 3b, 3c the metal centre competes with the coordinated ethene for binding to nucleophiles; therefore the acetylacetonate anion can either add to the olefin (affording compounds 6b, 6c ) or to the metal ion replacing the ethene ligand (yielding compounds 7b, 7c). Under similar conditions, 3a gives exclusively 6a. Secondary amines readily add to ethene in 3b, 3c, affording the addition products 8b, 8c, which undergo a ready cyclization to an azaplatinacyclobutane ring (9b, 9c). The remarkable ease of the four-membered ring formation has been related to the high electrophilic character of the metal core in 3b, 3c.

The unexpected reactivity of Zeise's anion in strong basic medium discloses new substitution patterns at the platinum centre

Zeise's anion in strongly basic hydroxylated solvents undergoes unprecedented nucleophilic addition of OR- (R = H, Me, Et) to the eta2-ethene giving trans-[PtCl2(eta1-C2H4OR)(OR)]2- which readily reacts with bidentate nitrogen donors N-N to give Cl- and OR- substitution and formation of [PtCl(CH2CH2OR)(N-N)]. Protonolysis of this stable organometallic species offers a versatile route to cationic [PtCl(eta2-C2H4)(N-N)]+ complexes.

Synthesis and Structures of Zeise‐type Complexes with Vinylsilane Ligands and Quantum Chemical Analysis of the Platinum–Vinylsilane Bonding

AbstractZeise‐type complexes with vinylsilanes as π‐ligands [K(18C6)][PtCl3(η2‐CH2=CHX)] (X = SiMe3, 4; SiPh3, 5; Si(OMe)3, 6; 18C6 = 18‐crown‐6) and [K(18C6)]2[(PtCl3)2{η2,η2‐(CH2=CHSiMe2)2O}] (7) have been prepared by the reaction of [K(18C6)]2[Pt2Cl6] (3) with the appropriate vinylsilanes. The identities of the complexes have been confirmed by NMR spectroscopy as well as for 4, 5 and (PPh4)[PtCl3{η2‐CH2=CHSi(OMe)3}] (6′) also by single‐crystal X‐ray diffraction measurements. DFT calculations exhibited, that the coordination induced C=C bond lengthenings and the pyramidalization angles of the olefins in the vinylsilane complexes [PtCl3(η2‐CH2=CHX)]− (X = SiMe3, 4c; SiPh3, 5c; Si(OMe)3, 6c) are the same as in Zeise's anion [PtCl3(η2‐CH2=CH2)]− (8c) while the amount of the π back‐donation in the vinylsilane complexes 4c–6c is higher than that in the ethylene complex 8c.

Synthesis and Characterization of Alkoxide-Derived Pt Nanoparticles

Identification of the species formed during the in situ reduction of hexachloroplatinic acid by sodium ethoxide, forming a Pt sol, is made. The solution phase is shown to consist of suspended metallic Pt nanoparticles (1-3 nm in diameter), acetaldehyde, and a Pt(II) species, identified by NMR and X-ray adsorption near-edge spectroscopy (XANES) to be NaPtCl3(C2H4), a sodium analogue of Zeise's salt [KPtCl3(C2H4)]. The NaPtCl3(C2H4) product exhibits greater stability in both ethanol and air than the conventional Zeise's salt, providing a means of storing the useful Zeise's anion [PtCl3(C2H4)-]. Electrochemistry, X-ray diffraction (XRD), and transmission electron microscopy (TEM) analyses have shown that the precipitate phase formed during the synthesis is composed solely of Pt particles approximately 6 nm in diameter and NaCl. Thermal gravimetric analysis/differential scanning calorimetry (TGA/DSC) showed that the color of the precipitate is an accurate gauge of the ratio of Pt to NaCl, with the lightest to darkest precipitates containing from 1% to 40% nanoparticulate Pt by mass, respectively. A comprehensive characterization of both phases formed has allowed us to propose a mechanism for the conversion of hexachloroplatinic acid to Pt nanoparticles.

Low temperature kinetic study of very fast substitution reactions at platinum(ii) trans to olefins

Ultra-fast substitution of chloride for bromide, iodide, azide and thiocyanate trans to ethene in Zeise's anion, [PtCl3(C2H4)]−, 1, has been investigated in methanol solvent by use of cryo temperature diode array stopped-flow spectrophotometry. Reactions follow the usual two-term rate law for square-planar substitutions, kobs = k1 + k2[Y] (where k1 = kMeOH[MeOH]), with k1 = 118 ± 10 s−1 and k2 = (5.1 ± 0.2) × 102, (3.51 ± 0.07) × 103, (11.8 ± 0.2) × 103, and (56 ± 4) × 103 mol−1 dm3 s−1 for Y = Br−, I−, N3− and SCN−, respectively, at 223 K. Activation parameters for MeOH, Br−, I− and N3− are ΔH≠ = 23 ± 2, 21 ± 2, 17 ± 1.0 and 11.9 ± 1.5 kJ mol−1 and ΔS≠ = −124 ± 10, −96 ± 9, −98 ± 4 and −111 ± 6 J K−1 mol−1, respectively. Recalculation of k1 to second-order units gives the sequence of nucleophilicity MeOH < Br− < I− < N3− < SCN− (1 ∶ 100 ∶ 700 ∶ 2500 ∶ 12000) at 223 K. This nucleophilic discrimination decreases with increasing temperature. Chloride for iodide substitution trans to allyl alcohol, vinyltrimethylsilane and cyclooctene at [PtCl3(L)]−, (L = CH2CHCH2OH, 2; CH2CHSiMe3, 3; C8H14, 4) follow the same rate law with k1 = 116 ± 5, 31.0 ± 0.3 and 23.6 ± 0.1 s−1 and k2 = (2.65 ± 0.06) × 103, (0.273 ± 0.005) × 103 and (0.119 ± 0.002) × 103 mol−1 dm3 s−1 at 223 K. Activation parameters are ΔH≠(kMeOH) = 24.4 ± 1.3, 28.4 ± 0.6 and 29.9 ± 0.8 kJ mol−1, ΔS≠(kMeOH) = −120 ± 5, −114 ± 2 and, −108 ± 3 J K−1 mol−1, ΔH≠(k2) = 19.9 ± 1.2, 24.6 ± 1.7 and 24 ± 3 kJ mol−1 and ΔS≠ (k2) = −88 ± 5, −84 ± 7 and −93 ± 10 J K−1 mol−1, for 2, 3 and 4 respectively. The free energies of activation are dominated by the −TΔS≠ terms. The crystal and molecular structures of Bu4N[PtCl3(CH2CHSiMe3)] and Bu4N[PtCl3(C8H14)] show slight Pt–Cl bond lengthening to 2.314(2) A and 2.3238(16) A trans to the olefins, similar to that found trans to ethene in Zeise's anion. All experiments support a model for the very fast substitution reactions trans to the olefins in which ground state labilisation is much less significant than transition state stabilisation. Extrapolation to ambient temperature together with literature data for related reactions in methanol solvent gives a quantitative measure of the trans effect of ethene as: SR2 < Me2SO < AsEt3 < PR3 < P(OR)3 < C2H4 (1 ∶ 5 ∶ 400 ∶ 3500 ∶ 7000 ∶ 3 × 106). The relative trans effect of the olefins studied is C2H4 ∼ CH2CHCH2OH > CH2CHSiMe3 ∼ C8H14, spanning a factor of between 5 and 30 depending on the nucleophile, and reflecting minor differences in steric and electronic properties of the olefins.

Rehybridization in ethene ligand of Pt(II) in zeise's anion

In crystals, [(C 2H 4)PtCl 3] − contains a wedgewise distorted ethene ligand. Hybridization in the ligand was estimated using the “π-orbital axis vector” (POAV) analysis of the free C 2H 4 regular wedge (symmetry C 2v; angle between eclipsed CH 2 groups 146°; r(CC) = 137.5 pm). The original sp 2.000 hybridization of both C atoms in the planar molecule was changed to sp 2.065 in the wedge. The admixture of s character into p orbitais forming the π molecular orbital, ps m , has the value m = 0.022. The rehybridized p π orbitais form an angle of about 96° with all three σ bonds on each C atom. These results are in agreement with the idea of a chemically pseudo-excited state of this C 2H 4 monodentate ligand of Pt(II) within the stable complex ion.

Complex formation and kinematic coupling: C2H4.PtCl3

Normal coordinate analyses including calculations of PED's were performed for C2H4.PtCl3 system modelling Zeise's anion, [(C2H4)PtCl3]-. The wedgewise distorsion of the C2H4 ligand known from the crystallographic data for Zeise's salt, was taken into account. Under these circumstances it was found that the kinematic couplings between the internal ligand and complex framework vibrational modes are rather small. The reliability of some existing assignments of the fundamental frequencies of Zeise's anion is discussed.

Acidolysis of diamino complexes of platinum(II) with η-ethene: Preparation of some new complexes containing mono-quaternized ditertiary amines

The acidolysis of five-co-ordinate [Pt(C 2H 4)Cl 2(Me 4en)], (I), and four-co-ordinate [Pt(C 2H 4)Cl(Me 4en)](ClO 4), (II), (Me 4en = N,N,N′,N′-tetramethylethylenediamine), is controlled by the trans effect of the olefin. Compound ( I) reacts with HCl to give first ring open of the chelate diamine and formation of a species with monoprotonated singly-bonded diamine opposite to the unsaturated ligand, then displacement of the second end of the diamine with formation of Zeise's anion. Under analogous conditions compound ( II) forms cis-[Pt(C 2H 4)Cl 2(Me 4enH)] +, ( III), which reacts further with HCl to give displacement of ethene and formation of the zwitterion [PtCl 3(Me 4enH)], ( IV). This reaction sequence allows through the isolation of deal substrates to study ringclosing processes. Spectroscopic data for the new complexes containing the monoquaternized Me 4enH + ligand are report and discussed.

Zeise's anion as a system of strongly anharmonic coupled oscillators

Zeise's anion as a system of strongly anharmonic coupled oscillators

The bonding of ethylene to titanium halides: An SCF-Xα-scattered-wave study of clusters relevant to Ziegler—Natta catalysts

SCF—Xα—scattered-wave calculations on TiF 3− 6 and TiCl 3− 6 clusters demonstrate the large ionic character in the electronic structure of these complexes (and the related titanium trihalides). Excitation energies for d—d transitions and charge-transfer transitions are well reproduced. By replacing one L − ligand by ethylene to form [Ti(C 2H 4)L 5] 2− (L = F, Cl), model “surface complexes” are set up, relevant as intermediates in a Ziegler—Natta polymerization reaction. A comparison with Zeise's anion [Pt(C 2H 4)Cl 3] − shows a weaker bonding component, but significantly enlarged π* back- bonding. This is attributed to the different influence of the ligand environment on the metal d orbitals.

Ethylene Exchange in Zeise's Anion

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEthylene Exchange in Zeise's AnionRichard CramerCite this: Inorg. Chem. 1965, 4, 4, 445–447Publication Date (Print):April 1, 1965Publication History Published online1 May 2002Published inissue 1 April 1965https://doi.org/10.1021/ic50026a002RIGHTS & PERMISSIONSArticle Views126Altmetric-Citations54LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (383 KB) Get e-Alerts Get e-Alerts