Solvent-free mechanochemical synthesis of two Pt complexes: cis-(Ph3P)2PtCl2 and cis-(Ph3P)2PtCO3Electronic supplementary information (ESI) available: differential thermal analysis data, X-ray diffraction data. See http://www.rsc.org/suppdata/cc/b2/b203694k/ (original) (raw)
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Organometallics, 1987
The reaction of Pb(C0)3(P-t-BuzPh)3 (1) with 3 equiv of HCl at-50 O C results in immediate formation of PtHCl(CO)(P-t-Bu,Ph) (2) in which the hydride ligand is assigned to the position trans to the CO ligand. Complex 2 isomerizes rapidly at higher temperatures to give a second complex, PtHCl(CO)(P-t-BuzPh) (3), with the hydride ligand trans to the chloride ligand. Complex 3 slowly converts to a dinuclear Pt(1) complex shown by X-ray crystallography to be PtzC1z(CO)2(P-t-Bu2Ph)z (4). Complex 4 crystallizes in the monoclinic space group P2Jc with 2 = 4 in a unit cell of dimensions a = 15.418 (1) A, b = 14.751 (1) A, c = 16.051 (2) A, and p = 108.61 (1)". The structure was refined by using 4065 independent reflections with 203 variables to R1 = 0.046 and Rz = 0.053. 4 contains an unsupported Pt-Pt bond (2.628 (1) A), and the phosphine ligands are located trans to this bond. The Pt atom coordination spheres are essentially square-planar with a dihedral angle of 109.9" between the two planes. The rotational energy of the Pt-Pt bond and the relative stability of 4 and a hypothetical C1-bridged isomer are examined by using EHMO calculations. 4 also can be prepared by reacting 1.5 equiv of Clz with 1 while reaction of 1 or 4 with excess C12 gives Pt(Cl),(CO)(P-t-BuPh) (7). Addition of excess NaBH4 to a solution of 3 regenerates 1, and reaction of 3 with AgPF6 gives [ (Pt3(~-C0)3(P-t-Bu2Ph)3)zAg] [PF6] (6). Complex 6 has been spectroscopically characterized as a Ag cation sandwiched between two units of 1. 6 is also the product of the reaction of 1 and AgPF,. a Estimated standard deviations in the least significant figure(s) are given in parentheses. Anisotropically refined atoms are given in the form of the isotropic equivalent thermal parameter defined as (4/3)[a2~(1,i) + ~~(2 , 2) + c*~(3,3) + ab(cos y)~(1,2) + ac(cos B)B(1,3) + bc(cos a)B(2,3)]. cipitate was obtained by filtration; yields are quantitative; 'H
Chemistry of Materials, 2012
Crystal engineering through the use of metal-based interactions is relatively common, but this approach has not been widely used to develop highly ordered liquid-crystalline (LC) phases. Herein is presented a Pt(II)/Pt(IV) system with a highly ordered LC phase engineered to form through metal-based MX chain interactions of the type Pt(II)•••Cl-Pt(IV). This LC material constitutes a molecular alloy in which a single mesophase is formed from two components, and is the first alloy to include a Pt(IV) component. The molecular alloy was characterized via differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and variable-temperature X-ray diffraction (VT XRD). The alloy properties are contrasted with complimentary analyses of the individual components. The newly synthesized tetrachloro(dialkyl 4,4′dicarboxylate-2,2′-bipyridyl)platinum(IV) complexes (PtL n Cl 4 , n is the number of carbons in the alkyl chain) are themselves liquid crystalline. Structural and thermal properties of the Pt(II) analogues are presented to provide context to the behaviors of the Pt(IV) species and the alloys. Single-crystal X-ray diffraction data is presented for PtL 1 Cl 2 •CH 2 Cl 2 , PtL 2 Cl 2 , and PtL 16 Cl 2 ••2CHCl 3. This study demonstrates the potential of mesophase ordering through carefully engineered metal-based interactions. The resulting alloy provides a phase for studying MX chain interactions outside of the solid state.
A structure investigation of Pt-Co bimetallic catalysts fabricated by mechanical alloying
Materials Chemistry and Physics, 2009
Three Pt-Co mixtures of composition Pt25Co75, Pt50Co50 and Pt75Co25 respectively, were synthesized using the high-energy ball milling technique of the elemental powders with a view to prepare catalysts for fuel cells. The kinetics of phase evolution, their structure and average microstructure properties were quantitatively investigated by x-ray powder diffraction with the Rietveld method. The results show that the ball milling technique is able to produce Pt-Co solid solutions soon after few minutes of mechanical treatment. Of the two polymorphs of cobalt the fcc allotrope appears to be involved preferentially in the early stage of alloying reaction with fcc platimum. For the three compositions, a sigmoidal equation based on a interdiffusion-controlled mechanism satisfactorily accounts for the evolution of the solid solution as a function of mechanical treatment time. A characteristic reaction time of 3-6 h is observed for the solid state transformation reaction with the milling conditions adopted in our reactor. In the case of the Pt25Co75 composition, a competitive-consecutive reaction is observed. Lattice parameters of the solid solutions after extended times of milling and related atomic volumes turn out to be slightly above the values ideally predicted on the basis of the Vegard law. For the Pt75Co25 composition the average crystallite size is reduced down to ca 150 Å after 12 h when the lattice microstrain is also at a maximum, but further mechanical treatment tends to increase the average crystal size value and to decrease the strain. Similar results are found for equiatomic and Co-rich compositions. Annealing of the alloyed equiatomic powders effects a cubic-to-tetragonal transformation which is already operative at 600°C. In facts, after this treatment two tetragonal phases are observed. Further thermal treatment and annealing at 700 °C induces peak sharpening of the diffraction patterns, on account of ordering phenomena still in progress.
Powder Diffraction, 2016
X-ray powder diffraction data, unit-cell parameters, and space group for a new memantine analogue of a Platinum (Pt) (II) complex labelled LA-13, C 12 H 24 Cl 2 N 2 Pt, are reported [a = 8.324(1) Å, b = 27.838 (2) Å, c = 7.113(1), β = 111.25(1), unit-cell volume V = 1536.26 Å 3 , Z = 4, and space group P2 1 /n]. All measured lines were indexed and are consistent with the P2 1 /n space group. No detectable impurity was observed.
PtxGd alloy formation on Pt(111): Preparation and structural characterization
Surface Science, 2016
Pt x Gd single crystals have been prepared in ultra high vacuum (UHV). This alloy shows promising catalytic properties for the oxygen reduction reaction. The samples were prepared by using vacuum deposition of a thick layer of Gd on a sputter cleaned Pt(111) single crystal, resulting in a ∼63 nm thick alloy layer. Subsequently the surfaces were characterized using X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED), ion scattering spectroscopy (ISS) and temperature programmed desorption (TPD) of CO. A Pt terminated alloy was observed upon annealing the sample to 600 • C. The LEED and synchrotron XRD experiments have shown that a slightly compressed (2×2) alloy appear. The alloy film followed the orientation of the Pt(111) substrate half the time, otherwise it was rotated by 30 •. The TPD spectra show a well-defined peak shifted down 200 • C in temperature. The crystal structure of the alloy was investigated using ex-situ X-ray diffraction experiments, which revealed an in-plane compression and a complicated stacking sequence. The crystallites in the crystal are very small, and a high degree of twinning by merohedry was observed.
Powder Diffraction, 2010
X-ray powder diffraction data, unit-cell parameters, and space group for a novel platinum-based anticancer complex cis-͓diiodo͑1R ,2R͒-1,2-diaminocyclo-hexane-N , NЈ͔ platinum͑II͒, Pt͑C 6 H 14 N 2 ͒I 2 , are presented ͓a = 14.048͑4͒ Å, b = 7.588͑3͒ Å, c = 11.502͑4͒ Å,  = 98.446͑5͒°, space group C2, cell volume= 1212.80 Å 3 , and Z =4͔. All measured lines were indexed and are consistent with the C2 space group. No detectable impurities were observed.
Inorganic Chemistry, 1993
The crystal structures of the pure monoclinic and orthorhombic phases of [Pt(en)2] [Pt(en)2C12](C104)4 (PtC1) and [Pt(en)2] [Pt(en)~Br2](C104)~ (PtBr), with en = 1,2-diaminoethane, were determined at several temperatures. The monoclinic phase of PtCl has space group E 1 / m , with a = 7.972(3) A, b = 10.874(5) A, c = 8.500(4) A, j3 = 108.91(4)", Z = 2, d = 2.619 g/cm3, and T = -20 "C. The monoclinic phase of PtBr crystallizes in space group P2'/m, with a = 7.959(2) A, b = 10.957(2) A, c = 8.529(2) A, j3 = 109.32(3)", Z = 2, d = 2.811 g/cm3, and T = 25 OC. The orthorhombic phase of PtCl has space group Zbam, with a = 13.594(4) A, b = 9.657(5) A, c = 10.855(4) A, 2 = 4, d = 2.562 g/cm3, and T = 25 OC. The orthorhombic phase of PtBr crystallizes in space group Zbam, with a = 13.671(5) A, b = 9.680(3) A, c = 10.994(3) A, Z = 4, d = 2.712 g/cm3, and T = 40 "C. The monoclinic phases of PtCl and PtBr were also determined at T = -70 and -93 "C, respectively. The lattice constants forPtCl(-70 "C) area = 7.947(4) A, b = 10.871(5) & c = 8.445(5) &and@ = 108.79(4)", and thelatticeconstants for PtBr(-93 "C) are a = 7.912(2) A, b = 10.900(2) A, c = 8.387(2) A, and j 3 = 109.02(3)". The corresponding PtCl and PtBr phases are isostructural. These systems contain chains composed of alternating, octahedral Pt(en)2Xz
Inorganic Chemistry, 1984
The new linear trimetallic complexes tran~-Pt[M(C0)~Cp],(PhCN), [M = Cr (la), Mo (Za), W (3a)l have been isolated and characterized. The isocyanide complexes tram-Pt [ Cr(CO) ,Cp] 2(t-BuNC), (lb) and trans-Pt [ Cr (CO) ,Cp] , [ c-C6H I 'NC] , (IC) have also been prepared because they are related to la. The first reported u(Pt-Cr) frequencies are 173, 174, and 177 cm-I for la-c, respectively. The complex tran~-Pt[Mn(C0),]~(PhCN)~ (4a) has also been synthesized. It reacts with PPh, to give the Pt5(CO)6(PPh,)4 cluster and with CO to afford the linear trimetallic trans-Pt[Mn(CO)S]2(C0)2 (4) complex. The syntheses, characterizations, and X-ray structures of a family of new heterotetrametallic clusters Pt2M2Cp2(C0)6(PR,), [Cp = q5-C5H5; M = Cr (5), Mo (6), W (7); R = Me (e), Et (f), n-Bu (g), Ph (h)] are described. Two different synthetic routes have been shown to lead to these clusters. In method A, the PtC12(PR,), complexes were reacted with 2 equiv of Na[M(CO),Cp] in THF. A complex redox reaction occurs, accompanied by ligand transfer and cluster formation. Thus, the dimers [M(C0)3Cp]2 and/or derivatives thereof such as the new Mo2(CO),(PMe3)Cp, were obtained, together with the mixed-metal clusters in which only one PR3 ligand is coordinated to each Pt atom. Method B involves the reaction in T H F of 1 equiv of phosphine with the linear trimetallic complexes la-3a. Substitution of PhCN for PR, induces a fragmentation of the complex into reactive units that combine with each other, affording the stable compounds. Mechanisms involving radical intermediates are proposed for these reactions. In general, method B presents significant advantages over method A, namely (i) higher cluster yield (up to 87%), (ii) a readily available stable platinum precursor, and (iii) generality and economy of introduction of a phosphine ligand into a cluster molecule. An X-ray diffraction study has been performed on the complexes Pt2M2Cp2(ps-C0)2(p-C0)4(PEt3)2 [M = Cr (5f), Mo (60, W (701. Data for 5f monoclinic, space group R l / c with Z = 2, a = 10.765 (6) A, b = 9.430 (4) A, c = 17.450 (5) A, 0 = 115.37 (2)O, p(ca1cd) = 2.13 g cm-,. For 2321 reflections with I > 3 4 , R = 0.032. Data for 6 f triclinic, space group Pi with Z = 2, a = 10.026 (2) A, b = 11.155 (4) A, c = 15.126 (4) A, a = 85.17 (2)O, j3 = 75.44 (2)O, y = 84.33 (2)O, p(ca1cd) = 2.29 g cm-,. For 4574 reflections with I > 3 4 8 , R = 0.051. There are two slightly different molecules, A and B, in the unit cell. Complex 7f crystallizes in two different monoclinic cells, of P2,/n space group with Z = 2: a = 8.768 (7), 11.920 (2) %.; 6 = 14.147 (2), 12.930 (6) A; c = 13.580 (6), 12.166 (3) A; j3 = 77.96 (5), 61.72 (2)'; p(ca1cd) = 2.60 g cm-,; 2365, 1921 reflections with I > 3 4 8 , R = 0.033,0.085 for types A and B, respectively. All these structures are characterized by a planar, triangulated parallelogram framework for the metallic core. The center of symmetry of these molecules is at the middle of the Pt-Pt' bond. This distance is rather short, ranging from 2.612 (1) (in 5f) to 2.677 (1) %. (in 6f A). The Pt-M distances have values of 2.748 (1) and 2.709 (1) A for M = Cr and range from 2.777 (2) to 2.846 (1) A for M = Mo and from 2.775 (1) to 2.836 (1) A for M = W. A shorter Pt-M distance is found where the contributions of the bridging carbonyls on this bond is higher. In these 58-electron clusters, the 18-electron [CpM(CO),]-fragments bridge the L-+Pt(I)-Pt(I)+L unit in a very original way: a three-legged piano-stool structure with the two Pt atoms located within the M(CO), cone. Each PEt, ligand is coordinated to a Pt atom with a Pt'-Pt-P angle between 169.7 (1) and 177.7 (1)O and an average Pt-P distance of 2.285 A. The planes of the $-Cp ligands are by symmetry parallel to each other and form a dihedral angle between 75.6 and 86.9' with the metallic plane. The carbonyl ligands C(1)0(1) and C(3)0(3) are semibridging the M-Pt' and M-Pt edges, respectively, whereas C(2)0(2) is semi triply bridging the heterotrimetallic face MPtPt'. By symmetry, an identical geometry is found with the carbonyls bridging M'Pt,M'Pt' and M'PtPt'. This bonding situation is compared in the Pt2Cr2, Pt2M02, and Pt2W2 clusters and related to the difference observed between the Pt-M and Pt'-M distances. Spectroscopic, IR, and 'H, 13C('HJ, and 31P[1H) N M R data indicate that all the Pt2M2 clusters presented here have the same basic structures as 5f, 6f, and 7f and that the solid-state structure is retained in solution. 'J(PtPt) values of 775 and 1039 Hz were found for 6g and 7g, respectively. trun~-Pt[M(C0)~Cp]~(PhCN)~. The synthesis and charac-(1) Organometallic Complexes with Metal-Metal Bonds. 19.