A New Class of Oligonuclear Platinum-Thallium Compounds with a Direct Metal−Metal Bond - 3. Unusual Equilibria in Aqueous Solution

Maliarik, Mikhail; Glaser, Julius; Tóth, I.; Silva, Mateus Webba da; Zékány, László

doi:10.1002/(sici)1099-0682(199805)1998:5<565::aid-ejic565>3.0.co;2-y

Cited by 25 publications

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“…Formation and characterisation of the solid TlPt(CN) 5 compound : The equilibrium between the bimetallic species [(NC) 5 Pt−Tl(CN) n ] n − in aqueous solution at high acidity and/or low free‐cyanide concentration is shifted toward the uncharged complex [(NC) 5 Pt−Tl(H 2 O) x ] 6d. Slow precipitation of a white powder occurs from such solutions.…”

Section: Resultsmentioning

confidence: 99%

“…The hydrolysed and protonated species are in fast exchange on the Tl NMR timescale in aqueous solution; this prevents their separate detection. In aqueous solutions of ionic cyanides, the formation of [(NC) 5 Pt−Tl(CN) n ] n − ( n =1–3) species leads to higher solubility of the solid compound 6b,6d. Thus the formation conditions, the dissolution products and the stoichiometric composition, TlPt(CN) 5 , of the solid powder strongly indicate that its structure is closely related to that of the neutral hydrated complex [(NC) 5 Pt−Tl(H 2 O) x ], which is formed in aqueous solution.…”

Section: Resultsmentioning

confidence: 99%

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Tl−Pt(CN)5 in the Solid State—A Multimethod Study of an Unusual Compound Containing Inorganic Wires

et al. 2001

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The crystal and molecular structure of a polycrystalline powder with a metal-metal bond and the composition TlPt(CN)5 has been determined by combining results from X-ray powder diffraction (XRD), extended X-ray absorption fine structure (EXAFS) and vibrational spectroscopic studies. The XRD data gave the tetragonal space group P4/nmm (No. 129), with a= 7.647(3), c=8.049(3) A, Z=2, and well-determined positions of the heavy metal atoms. The Pt-TI bond length in the compound is 2.627(2) A. The platinum atom coordinates four equivalent equatorial cyano ligands, with a fifth axial CN ligand and a thallium atom completing a distorted octahedral coordination geometry. The Tl-Pt(CN)5 entities are linked together in linear -NC-Pt-Tl-NC-Pt-Tl chains through the axial cyano ligand. These linear "wires" are the essential structural features and influence the properties of the compound. A three-dimensional network is formed by the four equatorial cyano ligands of the platinum atom that form bridges to the thallium atoms of neighbouring antiparallel chains. The platinum atom and the five nitrogen atoms from the bridging cyano groups form a distorted octahedron around the thallium atom. EXAFS data were recorded at the Pt and Tl L(III) edges for a more complete description of the local structure around the Pt and Tl atoms. The excessive multiple scattering was evaluated by means of the FEFF program. Raman and infrared absorption spectroscopy reveal strong coupling of the vibrational modes of the TlPt(CN)5 entities, in particular the metal-metal stretching mode, which is split into four Raman and two IR bands. Factor group theory shows that a structural unit larger than the crystallographic unit cell must be used to assign vibrational bands. Intra- and intermolecular force constants have also been calculated. The compound exhibits red luminescence at 700 +/- 3 nm in glycerol and has a corresponding excitation maximum at 240 nm. X-ray photoelectron spectra (XPS) show that the metal atoms have intermediate oxidation states, Pt3.2+ and Tl1.6-, between those in the parent Pt(II) and Tl(III) species and the decomposition products, Pt(IV) and Tl(I). The solid compound TlPt(CN)5 is stable to 520 degrees C. However in presence of water, a two-electron transfer between the metal atoms results in the cleavage of the metal-metal bond at 80 degrees C, forming a Pt(IV) pentacyanohydrate complex and a monovalent thallium ion.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Tl−Pt(CN)5 in the Solid State—A Multimethod Study of an Unusual Compound Containing Inorganic Wires

et al. 2001

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“…Found: Pt, 54.4; Na, 12.6. Bimetallic Pt−Tl cyano complexes in aqueous solution were prepared by mixing solutions of Pt(CN) 4 2- and Tl(CN) n 3- n (n = 2−4) at different Pt/Tl and cyanide-to-metal ratios as described previously. , The solid compound, [(NC) 5 PtTl], was precipitated from the solution containing the corresponding complex and 1.5 M perchloric or nitric acid …”

Section: Methodsmentioning

confidence: 99%

“…Recently, we reported our structural , and equilibrium studies of the family of oligometallic platinum−thallium cyano compounds containing (NC) 5 Pt- unit(s) directly bonded to the thallium atom. The complexes can be viewed as metastable intermediate products of the electron-transfer reaction between Pt(II) and Tl(III) leading to Pt(IV) and Tl(I).…”

Section: Introductionmentioning

confidence: 99%

Novel Pentacyano Complexes of Tri- and Tetravalent Platinum

1998

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New pentacyano complexes of tri- and tetravalent platinum were obtained in aqueous solution and characterized by multinuclear NMR ((195)Pt, (13)C) supported by Raman spectroscopy. The complexes form as products of redox decomposition of metal-metal bonded platinum-thallium compounds. The trimetallic [(NC)(5)Pt-Tl-Pt(CN)(5)](3)(-) yields a new dimeric compound of Pt(III), [(NC)(5)Pt-Pt(CN)(5)](4)(-). The latter is a rare representative of unbridged dimeric complexes of trivalent platinum; it was obtained through an oxidation of monomeric square-planar platinum(II) species by a metal complex. From the bimetallic compounds [(NC)(5)Pt-Tl(CN)(n)()](n)()(-) (n = 0-2) tetravalent platinum complexes are formed. Depending on the Pt-Tl species, electron transfer is initiated either by heat or by exposition to light; it results in [Pt(CN)(6)](2)(-) or in the hitherto unknown complexes [Pt(CN)(5)(OH)](2)(-) and [Pt(CN)(5)(H(2)O)](-), with the (195)Pt NMR chemical shift values 1638.7 (+/-0.6) and 1766.7 (+/-0.6), respectively. Proton dissociation constant of [Pt(CN)(5)(H(2)O)](-) has been determined, pK(a) = 2.51 (+/-0.01). In both Pt(III) and Pt(IV) pentacyano complexes platinum is hexacoordinated forming a pseudo-octahedron with two types of cyano ligands: four equivalent equatorial cyanides and one apical. Related platinum(IV) species, [Pt(CN)(5)X](2)(-) (X = Cl, Br, I), have also been studied. In all the pentacyano complexes a pronounced trans influence is reflected in a substantial difference between the (195)Pt-(13)C spin-spin coupling constant for the apical (trans) and the equatorial (cis) carbon sites. In this respect, the studied X ligands can be ordered in a series of decreasing (195)Pt-(13)C(trans) coupling constant: H(2)O > Cl(-) > Br(-) > I(-) > OH(-) > CN(-).

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“…The group of Glaser has recently synthesized an entire series of solid compounds, containing groups of the general type [(NC) 5 Pt-Tl(CN) n ] nÀ (n ¼ 0-3) with very short apparent Pt-Tl bonds around 260 pm. [1][2][3][4][5] These values can be compared with the pure 6ss bond in Au 2 (247 pm), or its isoelectronic analogues. 6 They are shorter than the nominally (5ds) 2 Au(II)-Au(II) bonds of around 270 pm 7,8 or the nominal (5ds) 2 Mo-Mo or W-W single bonds around 296-298 and 299 pm respectively.…”

Section: Introductionmentioning

confidence: 99%

On the nature of the short Pt–Tl bonds in model compounds [H₅Pt–TlH_n]ⁿ⁻

Pyykkö

Patzschke

2003

Faraday Discuss.

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A New Class of Oligonuclear Platinum-Thallium Compounds with a Direct Metal−Metal Bond - 3. Unusual Equilibria in Aqueous Solution

Cited by 25 publications

References 21 publications

Tl−Pt(CN)5 in the Solid State—A Multimethod Study of an Unusual Compound Containing Inorganic Wires

Tl−Pt(CN)5 in the Solid State—A Multimethod Study of an Unusual Compound Containing Inorganic Wires

Novel Pentacyano Complexes of Tri- and Tetravalent Platinum

On the nature of the short Pt–Tl bonds in model compounds [H₅Pt–TlH_n]ⁿ⁻

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A New Class of Oligonuclear Platinum-Thallium Compounds with a Direct Metal−Metal Bond - 3. Unusual Equilibria in Aqueous Solution

Cited by 25 publications

References 21 publications

Tl−Pt(CN)5 in the Solid State—A Multimethod Study of an Unusual Compound Containing Inorganic Wires

Tl−Pt(CN)5 in the Solid State—A Multimethod Study of an Unusual Compound Containing Inorganic Wires

Novel Pentacyano Complexes of Tri- and Tetravalent Platinum

On the nature of the short Pt–Tl bonds in model compounds [H5Pt–TlHn]n−

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On the nature of the short Pt–Tl bonds in model compounds [H₅Pt–TlH_n]ⁿ⁻