| 1. |
- Maliarik, Mikhail, et al.
(författare)
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Metal-metal bonding in tetracyanometalates (M = Pt-II, Pd-II, Ni-II) of monovalent thallium. Crystallographic and spectroscopic characterization of the new compounds Tl2Ni(CN)(4) and Tl2Pd(CN)(4)
- 2007
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 46:11, s. 4642-4653
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Tidskriftsartikel (refereegranskat)abstract
- The new crystalline compounds Tl2Ni(CN)(4) and Tl2Pd(CN)(4) were synthesized by several procedures. The structures of the compounds were determined by single-crystal X-ray diffraction. The compounds are isostructural with the previously reported platinum analogue, Tl2Pt(CN)(4). A new synthetic route to the latter compound is also suggested. In contrast to the usual infinite columnar stacking of [M(CN)(4)](2-) ions with short intrachain M-M separations, characteristic of salts of tetracyanometalates of Ni-II, Pd-II, and Pt-II, the structure of the thallium compounds is noncolumnar with the two Tl-I ions occupying axial vertices of a distorted pseudo-octahedron of the transition metal, [MTl2C4]. The Tl-M distances in the compounds are 3.0560(6), 3.1733(7), and 3.140(1) A for Ni-II, Pd-II, and Pt-II, respectively. The short Tl-Ni distance in Tl2Ni(CN)(4) is the first example of metal-metal bonding between these two metals. The strength of the metal-metal bonds in this series of compounds was assessed by means of vibrational spectroscopy. Rigorous calculations, performed on the molecules in D-4h point group symmetry, provide force constants for the Tl-M stretching vibration constants of 146.2, 139.6, and 156.2 N/m for the Ni-II, Pd-II, and Pt-II compounds, respectively, showing the strongest metal-metal bonding in the case of the Tl-Pt compound. Amsterdam density-functional calculations for isolated Tl2M(CN)(4) molecules give Tl-M geometry-optimized distances of 2.67, 2.80, and 2.84 A for M = Ni-II, Pd-II, and Pt-II, respectively. These distances are all substantially shorter than the experimental values, most likely because of intermolecular Tl-N interactions in the solid compounds. Time-dependent density-functional theory calculations reveal a low-energy, allowed transition in all three compounds that involves excitation from an a(1g) orbital of mixed Tl 6p(z)-M nd(z)(2) character to an a(2u) orbital of dominant Tl 6p(z) character.
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| 2. |
- Chen, W. Z., et al.
(författare)
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Spectral and structural characterization of amidate-bridged platinum-thallium complexes with strong metal-metal bonds
- 2006
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 45:11, s. 4526-4536
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Tidskriftsartikel (refereegranskat)abstract
- The reactions of [Pt(NH3)(2)((NHCOBu)-Bu-t)(2)] and TlX3 (X = NO3-, Cl-, CF3CO2-) yielded dinuclear [{Pt(ONO2)(NH3)(2-)((NHCOBu)-Bu-t)}Tl(ONO2)(2)(MeOH)] (2) and trinuclear complexes [{PtX(RNH2)(2)((NHCOBu)-Bu-t)(2)}(2)Tl](+) [X = NO3- (3), Cl- (5), CF3CO2- (6)], which were spectroscopically and structurally characterized. Strong Pt-Tl interaction in the complexes in solutions was indicated by both Pt-195 and Tl-205 NMR spectra, which exhibit very large one-bond spin-spin coupling constants between the heteronuclei ((1)J(PtTl)), 146.8 and 88.84 kHz for 2 and 3, respectively. Both the X-ray photoelectron spectra and the Pt-195 chemical shifts reveal that the complexes have Pt centers whose oxidation states are close to that of Pt-III. Characterization of these complexes by X-ray diffraction analysis confirms that the Pt and Tl atoms are held together by very short Pt-Tl bonds and are supported by the bridging amidate ligands. The Pt-Tl bonds are shorter than 2.6 angstrom, indicating a strong metal-metal attraction between these two metals. Compound 2 was found to activate the C-H bond of acetone to yield a platinum(IV) acetonate complex. This reactivity corresponds to the property of Pt-III complexes. Density functional theory calculations were able to reproduce the large magnitude of the metal-metal spin-spin coupling constants. The couplings are sensitive to the computational model because of a delicate balance of metal 6s contributions in the frontier orbitals. The computational analysis reveals the role of the axial ligands in the magnitude of the coupling constants.
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| 3. |
- Gustafsson, Magnus, et al.
(författare)
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Novel Polynuclear Nickel(II) Complex : Hydrazine, Sulfato, and Hydroxo Bridging in an Unusual Metal Hexamer. Crystal Structure and Magnetic Properties of [Ni-6(N2H4)(6)(SO4)(4)(OH)(2)(H2O)(8)](SO4)(H2O)(10)
- 2010
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 49:12, s. 5359-5361
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Tidskriftsartikel (refereegranskat)abstract
- A reaction between nickel(II) sulfate and hydrazine in aqueous solution yields blue crystals of [Ni-6(N2H4)(6)(SO4)(4)(OH)(2)(H2O)(8)] (SO4)(H2O)(10). The compound has been characterized by single, crystal and powder X-ray diffraction, vibrational spectroscopy, as well as variable-temperature magnetic susceptibility. This is the first reported crystal structure of the nickel(II) complex with hydrazine. The complex cation in the compound has a remarkable structure with unusual diversity of bridging groups including hydrazine molecules, sulfate ions, and hydroxo groups. Hydrazine molecules bridge nickel ions into trimers, which are further linked into hexamers through bridging sulfates. The magnetic susceptibility study of the compound reveals antiferromagnetic interaction between nickel(II) ions in the polynuclear complex.
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| 4. |
- Joszai, R., et al.
(författare)
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Metal-metal bond or isolated metal centers? Interaction of Hg(CN)(2) with square planar transition metal cyanides
- 2005
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 44:26, s. 9643-9651
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Tidskriftsartikel (refereegranskat)abstract
- Three adducts have been prepared from Hg(CN)(2) and square planar M-II(CN)(4)(2-) transition metal cyanides (M = Pt, Pd, or Ni, with d(8) electron shell) as solids. The structure of the compounds K2PtHg(CN)(6)center dot 2H(2)O (1), Na2PdHg(CN)(6)center dot 2H(2)O (2), and K2NiHg(CN)(6)center dot 2H(2)O (3) have been studied by single-crystal X-ray diffraction, XPS, Raman spectroscopy, and luminescence spectroscopy in the solid state. The structure of K2PtHg(CN)(6)center dot 2H(2)O consists of one-dimensional wires. No CN- bridges occur between the heterometallic centers. The wires are strictly linear, and the Pt(II) and Hg(II) centers alternate. The distance d(Hg-Pt) is relatively short, 3.460 angstrom. Time-resolved luminescence spectra indicate that Hg(CN)2 units incorporated into the structure act as electron traps and shorten the lifetime of both the short-lived and longer-lived exited states in 1 compared to K-2[Pt(CN)(4)]center dot 2H(2)O. The structures of Na2PdHg(CN)(6)center dot 2H(2)O and K2NiHg(CN)(6)center dot 2H(2)O can be considered as double salts; the lack of heterometallophilic interaction between the remote Hg(II) and Pd(II) atoms, d(Hg-Pd) = 4.92 angstrom, and Hg(II) and Ni(II) atoms, d(Hg-Ni) = 4.61 angstrom, is apparent. Electron binding energy values of the metallic centers measured by XPS show that there is no electron transfer between the metal ions in the three adducts. In solution, experimental findings clearly indicate the lack of metal-metal bond formation in all studied Hg-II-CN--M-II(CN)(4)(2-) systems (M = Pt, Pd, or Ni).
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| 5. |
- Ma, Gui-Bin, et al.
(författare)
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Modification of binuclear Pt-Tl bonded complexes by attaching bipyridine ligands to the thallium site
- 2004
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 43:14, s. 4328-4340
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Tidskriftsartikel (refereegranskat)abstract
- Complex formation of monomeric thallium(III) species with 2,2'-bipyridine (bipy) in dimethyl sulfoxide (dmso) and acetonitrile solutions was studied by means of multinuclear (H-1, C-13, and (TI)-T-205) NMR spectroscopy. For the first time, NMR signals of the individual species [TI(bipy)(m)(SoIV)](3+) (M = 1-3) were observed despite intensive ligand and solvent exchange processes. The tris(bipy) complex was crystallized as [TI(biPY)(3)(dmso)](ClO4)(3)(dMSO)(2) (1), and its crystal structure determined. In this compound, thallium is seven-coordinated; it is bonded to six nitrogen atoms of the three bipy molecules and to an oxygen atom of dmso. Metal-metal bonded binuclear complexes [(NC)(5)Pt-TI(CN)(n)(SoIV)](n-) (n = 0-3) have been modified by attaching bipy molecules to the thallium atom. A reaction between [(NC)(5)Pt-TI(dMSO)(4)](s) and 2,2'-bipyridine in dimethyl sulfoxide solution results in the formation of a new complex, [(NC)(5)Pt-TI(bipy)(solv)]. The presence of a direct Pt-TI bond in the complex is convincingly confirmed by a very strong one-bond Pt-195-(TI)-T-205 spin-spin coupling ((1)J((195)pt-(TI)-T-205) = 64.9 kHz) detected in both Pt-195 and (TI)-T-205 NMR spectra. In solutions containing free cyanide, coordination of CN- to the thallium atom occurs, and the complex [(NC)(5)Pt-TI(bipy)(CN)(solv)](-) ((1)J(Pt-195-(TI)-T-205) = 50.1 kHz) is formed as well. Two metal-metal bonded compounds containing bipy as a ligand were crystallized and their structures determined by X-ray diffractometry: [(NC)(5)Pt-TI(bipy)(dMSO)(3)] (2) and [(NC)(5)Pt-TI(biPY)(2)] (3). The Pt-TI bonding distances in the compounds, 2.6187(7) and 2.6117(5) Angstrom, respectively, are among the shortest reported separations between these two metals. The corresponding force constants in the molecules, 1.38 and 1.68 N/cm, respectively, were calculated using Raman stretching frequencies of the Pt-TI vibrations and are characteristic for a single metal-metal bond. Electronic absorption spectra were recorded for the [(NC)(5)Pt-TI(bipy)(m)(solv)] compounds, and the optical transition was attributed to the metal-metal bond assigned.
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| 6. |
- Ma, Gui-Bin, et al.
(författare)
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Novel porphyrin-thallium-platinum complex with naked metal-metal bond : multinuclear NMR characterization of (tpp)Tl-Pt(CN)(5) (2-) and (thpp)Tl-Pt(CN)(5) (2-) in solution
- 2004
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Ingår i: Inorganica Chimica Acta. - : Elsevier BV. - 0020-1693 .- 1873-3255. ; 357:14, s. 4073-4077
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Tidskriftsartikel (refereegranskat)abstract
- The novel porphyrin-thallium-platinum complexes with naked metal-metal bond, with the composition [(tpp)Tl-Pt(CN)(5)](2-) (1) and [(thpp)Tl-Pt(CN)(5)](2-) (2) (tpp = tetraphenylporphrin and thpp = tetrakis(4-hydroxyphenyl)-porphine), were synthesized and characterised by multinuclear NMR (Tl-205, Pt-195, C-13 and H-1) and Raman spectroscopies in solution. The presence of a direct Pt-Tl metal-metal bond in the complexes is convincingly confirmed by a very strong one-bond Pt-195-Tl-205 spin-spin coupling (47.8 and 48.3 kHz for 1 and 2, respectively) detected in both Pt and Tl NMR spectra. The corresponding force constant in molecule 1, 1.92 Ncm(-1), was calculated using Raman stretching frequency of the Pt-T1 vibration and is characteristic for a single metal-metal bond.
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| 7. |
- Maliarik, Mikhail, 1964-
(författare)
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Compounds with Non-Buttressed Metal-Metal Bond between Platinum and Thallium. Model Systems for Photoinduced Two-Electron-Transfer.
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A new family of oligonuclear cyano compounds incorporatingtransition (Pt) and main group (Tl) metals bound with anon-buttressed Pt-Tl bond was synthesised in aqueous solution.The metal-metal linkage is formed in the reaction betweenplatinum and thallium in their stable oxidation forms, Pt(II)and Tl(III), orvice versa: Pt(IV) and Tl(I). Four binuclear complexeswith a general composition [(CN)5Pt-Tl(CN)n(aq)]n-(n = 0-3) and a trinuclear species [(NC)5Pt-Tl-Pt(CN)5]3-were identified and structurally characterised insolution by multinuclear NMR, EXAFS and vibrationalspectroscopy. In aqueous solution the complexes exist inequilibrium. The distribution between the species can bealtered by varying the molar ratio Pt/Tl, cyanide concentrationand pH. Stability constants of the compounds weredetermined.A new compound (NC)5PtTl was also prepared in solid and its crystalstructure solved by a combination of X-ray powder diffractionand EXAFS. Altogether the values of195Pt-205Tl spin-spin coupling constants (25-71 kHz),interatomic Pt-Tl distances (2.598-2.638 Å), and vibrationstretching frequencies v (Pt-Tl) (159-164 cm-1) are fully indicative of a direct and unsupportedPt-Tl bond. The calculated values of Pt-Tl force constants(1.56-1.74 N· cm-1) are characteristic for single metal-metal bond.The oxidation status in the compounds can be viewed asintermediate between II and IV for platinum, and between I andIII for thallium, as reflected by the chemical shifts of195Pt and205Tl nuclei, C≡ N stretching frequencies andelectron binding energies.The compounds are capable to undergo a photoinducedtwo-electron transfer between the coupled hetero-metal ions.Upon irradiation into the metal-to-metal charge transferabsorption band, effective photoredox reaction takes place. Itresults in scission of the Pt-Tl bond and formation of variouscomplexes of oxidised platinum (Pt(III, IV)) and reducedthallium (Tl(I)). The values of photodecomposition quantumyields were determined from a stationary photolysis study ofthe heterometallic complexes. Nanosecond laser flash photolysisof the heteronuclear Pt-Tl cyano compounds was performed in thetimescale range 1· 10-6- 5· 10-2s and several intermediate species were detectedand characterised by optical spectroscopy.The heteronuclear Pt-Tl cyano compounds can be furthermodified in terms of their stability, solubility, and lightabsorption characteristics. It has been found that the platinumpentacyano unit of the [(NC)5Pt-Tl(CN)n(aq)]n-species is inert towards the tested ligands,whereas the thallium "part" of the complexes can be tunedsignificantly. A number of complexes [(NC)5Pt-Tl(L)m]x-(L-ligand) were prepared and characterised insolution. Compounds [(NC)5Pt-Tl(nta)(H2O)]3-, [(NC)5Pt-Tl(bipy)(DMSO)3], and [(NC)5Pt-Tl(bipy)2]have been prepared in solid and their structuresdetermined by single-crystal X-ray diffraction.Keywords:thallium, platinum, cyanide, metal-metal bond,non-buttressed, heterobimetallic, photoinduced, electrontransfer, redox reaction, NMR, chemical shift, spin-spincoupling constant, Raman, EXAFS, X-ray diffraction,equilibrium, oxidation state, oxidative addition,photolysis
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| 8. |
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| 9. |
- Maliarik, Mikhail, et al.
(författare)
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Photoinduced electron transfer via nonbuttressed metal-metal bonds. The photochemical study of binuclear complexes with platinum-thallium bonds
- 2008
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Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 112:26, s. 5786-5793
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Tidskriftsartikel (refereegranskat)abstract
- The photochemistry of binuclear metal-metal bonded complexes [(NC) 5Pt-Tl(Solv)x] (solv is water or dimethylsulfoxide) has been studied in aqueous and dimethylsulfoxide solutions. Both stationary and nanosecond laser flash photolysis have been carried out on the species. The metal-metal bonded complexes have been photolyzed by irradiation into the corresponding intense MMCT absorption bands. Photoexcitation results in the cleavage of the platinum-thallium bond and the formation of a solvated thallous ion and a cyano complex of platinum(IV), [Pt(CN)5(Solv)]-, in both cases. The species have been characterized by multinuclear NMR and optical spectroscopy. The products of the photoreaction indicate a complementary two-electron transfer occurring between platinum and thallium ions in the binuclear Pt-Tl species. Quantum yield values for the photodecomposition of the species have been determined. The intermediates of the photoinduced metal-to-metal electron transfer have been detected and characterized by optical spectroscopy. The kinetics of transient formation and decomposition have been studied, and mechanisms of the photoactivated redox reaction have been suggested. © 2008 American Chemical Society.
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| 10. |
- Maliarik, Mikhail, et al.
(författare)
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The solvation of the mercury(II) ion - A 199Hg NMR study
- 2005
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Ingår i: Magnetic Resonance in Chemistry. - : Wiley. - 0749-1581 .- 1097-458X. ; 43:10, s. 835-842
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Tidskriftsartikel (refereegranskat)abstract
- The solvation of the mercury(II) ion in solvents with different solvation properties, water, dimethylsulfoxide, N,N-dimethylthioformamide, and liquid ammonia, has been studied by means of 199Hg NMR. The 199Hg chemical shift shows a pronounced dependence on the coordination number of the mercury(II) ion in the solvates resulting in a difference of over 1200 ppm between basically tetrahedral and octahedral complexes. The chemical shifts can furthermore be associated with electron-pair donor properties of the solvents. The spin-lattice relaxation times of the 199Hg nucleus in the solvates have been measured at different applied magnetic fields, concentrations, temperatures, and isotope substitutions. Possible mechanisms for the 199Hg relaxation were proposed and the chemical shielding anisotropy in the solvates has been estimated. The 199Hg relaxation rates and the anisotropy are correlated with the structure of the solvate complexes in solution obtained from recent LAXS and EXAFS studies. Copyright © 2005 John Wiley & Sons, Ltd.
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