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1.
Caneschi A Dei A Fabrizi de Biani F Gütlich P Ksenofontov V Levchenko G Hoefer A Renz F 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(18):3926-3930
An electronic switch at the molecular level has been realized by using a class of ionic compounds of the formula [Co(L)(diox)]Y (L = tetraazamacrocyclic ligand, Y = mononegative anion). Such compounds undergo temperature- and pressure-induced intramolecular one-electron transfer equilibria. The transition temperature of interconversion varies with the nature of the counterions Y (Y = PF6, BPh4, I). Surprisingly the effect of the anion on the transition temperature is not only governed by its volume but also by its coulombic interaction. 相似文献
2.
Fabrizi de Biani F Ienco A Laschi F Leoni P Marchetti F Marchetti L Mealli C Zanello P 《Journal of the American Chemical Society》2005,127(9):3076-3089
The reaction between equimolar amounts of Pt(3)(mu-PBu(t)()(2))(3)(H)(CO)(2), Pt(3)()H, and CF(3)SO(3)H under CO atmosphere affords the triangular species [Pt(3)(mu-PBu(t)()(2))(3)(CO)(3)]X, [Pt(3)()(CO)(3)()(+)()]X (X = CF(3)SO(3)(-)), characterized by X-ray crystallography, or in an excess of acid, [Pt(6)(mu-PBu(t)()(2))(4)(CO)(6)]X(2), [Pt(6)()(2+)()]X(2)(). Structural determination shows the latter to be a rare hexanuclear cluster with a Pt(4) tetrahedral core formed by joining the unbridged sides of two orthogonal Pt(3) triangles. The dication Pt(6)()(2+)() features also extensive redox properties as it undergoes two reversible one-electron reductions to the congeners [Pt(6)(mu-PBu(t)()(2))(4)(CO)(6)](+) (Pt(6)()(+)(), E(1/2) = -0.27 V) and Pt(6)(mu-PBu(t)()(2))(4)(CO)(6) (Pt(6)(), E(1/2) = -0.54 V) and a further quasi-reversible two-electron reduction to the unstable dianion Pt(6)()(2)()(-)() (E(1/2) = -1.72 V). The stable radical (Pt(6)()(+)()) and diamagnetic (Pt(6)()) species are also formed via chemical methods by using 1 or 2 equiv of Cp(2)Co, respectively; further reduction of Pt(6)()(2+)() causes fast decomposition. The chloride derivatives [Pt(6)(mu-PBu(t)()(2))(4)(CO)(5)Cl]X, (Pt(6)()Cl(+)())X, and Pt(6)(mu-PBu(t)()(2))(4)(CO)(4)Cl(2), Pt(6)()Cl(2)(), observed as side-products in some electrochemical experiments, were prepared independently. The reaction leading to Pt(3)()(CO)(3)()(+)() has been analyzed with DFT methods, and identification of key intermediates allows outlining the reaction mechanism. Moreover, calculations for the whole series Pt(6)()(2+)() --> Pt(6)()(2)()(-)()( )()afford the otherwise unknown structures of the reduced derivatives. While the primary geometry is maintained by increasing electron population, the system undergoes progressive and concerted out-of-plane rotation of the four phosphido bridges (from D(2)(d)() to D(2) symmetry). The bonding at the central Pt(4) tetrahedron of the hexanuclear clusters (an example of 4c-2e(-) inorganic tetrahedral aromaticity in Pt(6)()(2+)()) is explained in simple MO terms. 相似文献
3.
Francesco Demartin Fabrizia Fabrizi de Biani Cristina Femoni Maria Carmela Iapalucci Giuliano Longoni Piero Macchi Piero Zanello 《Journal of Cluster Science》2001,12(1):61-74
The [Ni36Pt4(CO)45]6- and [Ni37Pt4(CO)46]6- clusters have been obtained in mixture upon reaction in acetonitrile of [Ni6(CO)12]2- salts with K2PtCl4 in a 2.5:1 molar ratio. The two hexaanions were indistinguishable by spectroscopic techniques. Crystallization of their trimethylbenzylammonium salts led to crystals of composition 0.5[NMe3CH2Ph]6[Ni36Pt4(CO)45]-0.5[NMe3CH2Ph]6[Ni37Pt4(CO)46]·C3H8O, hexagonal,space group P63 (No. 173), a=17.853(9), c=27.127(13) Å, Z=2; final R=0.057. The metal core of the [Ni36Pt4(CO)45]6- anion consists of a Pt4 tetrahedron fully encapsulated in a shell of 36 Ni atoms belonging to a very distorted and incomplete 5 tetrahedron. The [Ni37Pt4(CO)46]6- hexaanion derives from the former by capping the unique triangular face of the metal polyhedron with an additional Ni(CO) fragment. The [Ni36Pt4(CO)45]6--[Ni37Pt4(CO)46]6- mixture is rapidly degraded to the known [Ni9Pt3(CO)21]4- cluster by exposure to carbon monoxide. Its reaction with protic acids initially affords the corresponding [H6-nNi36Pt4(CO)45]n--[H6-nNi37Pt4(CO)46]n- (n=5, 4) derivatives, and eventually leads to rearrangement to the known [H6-n Ni38Pt6(CO)48]n- species. Both [Ni36Pt4(CO)45]6--[Ni37Pt4(CO)46]6- and [HNi36Pt4(CO)45]5--[HNi37Pt4(CO)46]5- mixtures have been chemically and electrochemically reduced to their corresponding [Ni36Pt4(CO)45]n--[Ni37Pt4(CO)46]n- (n=7–9) and [HNi36Pt4(CO)45]n--[HNi37Pt4(CO)46]n- (n=6–8) mixtures. 相似文献
4.
Collini D De Biani FF Dolzhnikov DS Femoni C Iapalucci MC Longoni G Tiozzo C Zacchini S Zanello P 《Inorganic chemistry》2011,50(7):2790-2798
The previously ill-characterized [H(x)Rh(22)(CO)(35)](4-/5-) carbonyl cluster has been obtained as a byproduct of the synthesis of [H(3)Rh(13)(CO)(24)](2-) and effectively separated by metathesis of their sodium salts with [NEt(4)]Cl. Although the yields are modest and never exceed 10-15% (based on Rh), this procedure affords spectroscopically pure [H(3)Rh(22)(CO)(35)](5-) anion. Formation of the latter in mixture with other Rh clusters was also observed by electrospray ionization-mass spectrometry (ESI-MS) in the oxidation of [H(2)Rh(13)(CO)(24)](3-) with Cu(2+) salts. The recovery of further amounts of [H(3)Rh(22)(CO)(35)](5-) was hampered by too similar solubility of the salts composing the mixture. Conversely, the reaction in CH(3)CN of [H(2)Rh(13)(CO)(24)](3-) with [Cu(MeCN)(4)](+)[BF(4)](-) leads to the [H(2)Rh(13)(CO)(24){Cu(MeCN)}(2)](-) bimetallic cluster. The X-ray crystal structures of [H(4)Rh(22)(CO)(35)](4-), [H(3)Rh(22)(CO)(35)](5-), and [H(2)Rh(13)(CO)(24){Cu(MeCN)}(2)](-) are reported. From a formal point of view, the metal frame of the former two species can be derived by interpenetration along two orthogonal axes of two moieties displaying the structure of the latter. The availability of [H(8-n)Rh(22)(CO)(35)](n-) salts prompted their detailed chemical, spectroscopic, and electrochemical characterization. The presence of hydride atoms has been directly proved both by ESI-MS and (1)H NMR. Moreover, both [H(4)Rh(22)(CO)(35)](4-) and [H(3)Rh(22)(CO)(35)](5-) undergo distinctive electrochemically reversible redox changes. This allows to assess electrochemical studies as indisputable though circumstantial evidence of the presence of (1)H NMR-silent hydride atoms in isostructural anions of different charge. 相似文献
5.
Site selectivity in the reactions of the hexanuclear platinum cluster [Pt6(mu-PtBu2)4(CO)6][CF3SO3]2
Bonaccorsi C de Biani FF Leoni P Marchetti F Marchetti L Zanello P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(3):847-856
The previously reported hexanuclear cluster [Pt(6)(mu-PtBu(2))(4)(CO)(6)](2+)[Y](2) (1-Y(2): Y=CF(3)SO(3) (-)) contains a central Pt(4) tetrahedron bridged at each of the opposite edges by another platinum atom; in turn, four phosphido ligands bridge the four Pt-Pt bonds not involved in the tetrahedron, and, finally, one carbonyl ligand is terminally bonded to each metal centre. Interestingly, the two outer carbonyls are more easily substituted or attacked by nucleophiles than the inner four, which are bonded to the tetrahedron vertices. In fact, the reaction of 1-Y(2) with 1 equiv of [nBu(4)N]Cl or with an excess of halide salts gives the monochloride [Pt(6)(mu-PtBu(2))(4)(CO)(5)Cl](+)[Y], 2-Y, or the neutral dihalide derivatives [Pt(6)(mu-PtBu(2))(4)(CO)(4)X(2)] (3: X=Cl; 4: X=Br; 5: X=I). Moreover, the useful unsymmetrically substituted [Pt(6)(mu-PtBu(2))(4)(CO)(4)ICl] (6) was obtained by reacting equimolar amounts of 2 and [nBu(4)N]I, and the dicationic derivatives [Pt(6)(mu-PtBu(2))(4)(CO)(4)L(2)](2+)[Y](2) (7-Y(2): L=(13)CO; 8-Y(2): L=CNtBu; 9-Y(2): L=PMe(3)) were obtained by reaction of an excess of the ligand L with 1-Y(2). Weaker nitrogen ligands were introduced by dissolving the dichloride 3 in acetonitrile or pyridyne in the presence of TlPF(6) to afford [Pt(6)(mu-PtBu(2))(4) (CO)(4)L(2)](2+)[Z](2) (Z=PF(6) (-), 10-Z(2): L=MeCN; 11-Z(2): L=Py). The "apical" carbonyls in 1-Y(2) are also prone to nucleophilic addition (Nu(-): H(-), MeO(-)) affording the acyl derivatives [Pt(6)(mu-PtBu(2))(4)(CO)(4)(CONu)(2)] (12: Nu=H; 13: Nu=OMe). Complex 12 is slowly converted into the dihydride [Pt(6)(mu-PtBu(2))(4)(CO)(4)H(2)] (14), which was more cleanly prepared by reacting 3 with NaBH(4). In a unique case we observed a reaction involving also the inner carbonyls of complex 1, that is, in the reaction with a large excess of the isocyanides R-NC, which form the corresponding persubstituted derivatives [Pt(6)(mu-tPBu(2))(4)(CN-R)(6)](2+)[Y](2), (15-Y(2): R=tBu; 16-Y(2) (2-): R=-C(6)H(4)-4-C triple bond CH). All complexes were characterized by microanalysis, IR and multinuclear NMR spectroscopy. The crystal and molecular structures of complexes 3, 5, 6 and 9-Y(2) are also reported. From the redox viewpoint, all complexes display two reversible one-electron reduction steps, the location of which depends both upon the electronic effects of the substituents, and the overall charge of the original complex. 相似文献
6.
Barbara Di Credico Dipl.‐Chem. Fabrizia Fabrizi de Biani Dr. Luca Gonsalvi Dr. Annalisa Guerri Dr. Andrea Ienco Dr. Franco Laschi Prof. Dr. Maurizio Peruzzini Dr. Gianna Reginato Dr. Andrea Rossin Dr. Piero Zanello Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(44):11985-11998
The reaction of [CpRuCl(PPh3)2] (Cp=cyclopentadienyl) and [CpRuCl(dppe)] (dppe=Ph2PCH2CH2PPh2) with bis‐ and tris‐phosphine ligands 1,4‐(Ph2PC≡C)2C6H4 ( 1 ) and 1,3,5‐(Ph2PC≡C)3C6H3 ( 2 ), prepared by Ni‐catalysed cross‐coupling reactions between terminal alkynes and diphenylchlorophosphine, has been investigated. Using metal‐directed self‐assembly methodologies, two linear bimetallic complexes, [{CpRuCl(PPh3)}2(μ‐dppab)] ( 3 ) and [{CpRu(dppe)}2(μ‐dppab)](PF6)2 ( 4 ), and the mononuclear complex [CpRuCl(PPh3)(η1‐dppab)] ( 6 ), which contains a “dangling arm” ligand, were prepared (dppab=1,4‐bis[(diphenylphosphino)ethynyl]benzene). Moreover, by using the triphosphine 1,3,5‐tris[(diphenylphosphino)ethynyl]benzene (tppab), the trimetallic [{CpRuCl(PPh3)}3(μ3‐tppab)] ( 5 ) species was synthesised, which is the first example of a chiral‐at‐ruthenium complex containing three different stereogenic centres. Besides these open‐chain complexes, the neutral cyclic species [{CpRuCl(μ‐dppab)}2] ( 7 ) was also obtained under different experimental conditions. The coordination chemistry of such systems towards supramolecular assemblies was tested by reaction of the bimetallic precursor 3 with additional equivalents of ligand 2 . Two rigid macrocycles based on cis coordination of dppab to [CpRu(PPh3)] were obtained, that is, the dinuclear complex [{CpRu(PPh3)(μ‐dppab)}2](PF6)2 ( 8 ) and the tetranuclear square [{CpRu(PPh3)(μ‐dppab)}4](PF6)4 ( 9 ). The solid‐state structures of 7 and 8 have been determined by X‐ray diffraction analysis and show a different arrangement of the two parallel dppab ligands. All compounds were characterised by various methods including ESIMS, electrochemistry and by X‐band ESR spectroscopy in the case of the electrogenerated paramagnetic species. 相似文献
7.
Fulvio Rossi Fabrizia Fabrizi de Biani Piero Zanello Piotr Buchalski 《Journal of Solid State Electrochemistry》2009,13(10):1505-1510
A collection of nickelocene and cobaltocene analogs with one or two nickelafluorenyl rings has been recently synthesized starting
from 9-nickelafluorenyllithium complex. The redox ability of the whole series of derivates has been investigated by electrochemical
techniques, and the nature of the frontier orbitals responsible for the electron transfer activity of this class of compounds
has been supported by extended Hückel calculations.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
8.
9.
Schneider JJ Hagen J Spickermann D Bläser D Boese R de Biani FF Laschi F Zanello P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(2):237-246
The synthesis and structure of heterobimetallic Co/Sn complexes [(eta5-CpR)Co-Sn[CH(SiMe3)2]2] (CpR = C5Me5 2; C5EtMe4 3) are described. Insertion reactions of sulfur and selenium into the unbridged heteronuclear Co-Sn bonds of 1, 2, and 3 (R= H5 1, Me5 2, EtMe4 3) have been studied. Depending on the stoichiometry of the chalcogen element used, novel ternary Sn-chalcogen-Co clusters (8, 9, 15, and 16) can be synthesized, and their molecular structures, which represent rare examples of crystallographically characterized cases of ternary transition metal/chalcogen/tin complexes, have been determined. Electrochemistry shows that complexes 8 and 9 are able to support reversibly either the removal or addition of one electron. Insertion of a further (Cp)Co-E (E = chalcogen) fragment significantly affects the electron distribution and causes complexes 9 and 16 to undergo two consecutive one-electron oxidations. The EPR spectra of the respective monocations have been recorded. In all cases, the unpaired electron strongly interacts with the cobalt nucleus(i), thus testifying that the main contribution to the relevant HOMO orbitals comes from the cobalt atom(s). 相似文献
10.
A submillimeter spectrometer using the concept of generating continuosly tunable difference-frequency sideband by beating the HCN laser radiation and millimeter wave klystron radiation in the non-linear Schottky barrier diode has been developed for the accurate frequency measurement on32S16O gaseous sample at 820.151 GHz. The strength of the reradiated signal has been investigated as a function of generating laser and klystron power as well as of the d.c. bias applied externally to the diode. 相似文献