A Molecular Platinum Cluster Junction: A Single-Molecule Switch

We present a theoretical study of the electronic transport through single-molecule junctions incorporating a Pt6 metal cluster bound within an organic framework. We show that the insertion of this molecule between a pair of electrodes leads to a fully atomically engineered nano-metallic device with high conductance at the Fermi level and two sequential high on/off switching states. The origin of this property can be traced back to the existence of a HOMO which consists of two degenerate and asymmetric orbitals, lying close in energy to the Fermi level of the metallic leads. Their degeneracy is broken when the molecule is contacted to the leads, giving rise to two resonances which become pinned close to the Fermi level and display destructive interference.Comment: 4 pages, 4 figures. Reprinted (adapted) with permission from J. Am. Chem. Soc., 2013, 135 (6), 2052. Copyright 2013 American Chemical Societ

Inorganic Electrochemistry. Theory, Practice and Application, 2nd Edition

In order to understand the basic aspects of an electrochemical investigation on inorganic molecules (in its widest meaning, of any molecule which contains at least one metal centre) it must be taken into account that in these molecules the metal-ligand bonds are of the prevailingly covalent type. Since electrochemical techniques allow you to add or remove electrons in a controlled manner, it is conceivable that the addition or removal of electrons inside these molecules can lead to the formation of new bonds or to the breakage of existing bonds. The main aim of this book is to study the effects of such electron addition and removal processes on the molecular frames. The second edition of this classic book has been fully revised and updated and is a straightforward, logical introduction to electrochemical investigations for inorganic chemists. All chapters have been rewritten with new material including: - the addition of reactivity with nitric oxide to the chapter on the reactivity of metal complexes with small molecules - thiolate-protected gold nanoclusters has been added to the chapter on metal-sulfur and metal-carbonyl clusters - a new chapter on the digital simulation of electrochemical responses - a new chapter on the theoretical calculations to explain the nature of the electrochemical activity of metal complexes - new chapters on spectroelectrochemistry and electrochemiluminescence. The book covers every aspect of inorganic electrochemistry - the introduction is followed by chapters on the basic aspects of electrochemistry followed by practical and applicative aspects and ends with full appendices. It is probably the only publication with a simple approach to electrochemical aspects of the topics in inorganic chemistry. Bridging the gap between undergraduate and research-level electrochemistry books, this publication will be a welcome addition to the literature of inorganic chemists. It will also be particularly useful to final year students in chemistry and as background reading for graduates and researchers without adequate electrochemical knowledge to become active in the discipline or who want to collaborate with electrochemists

The redox behavior of 9-nickelafluorenyl sandwich complexes

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

Synthesis and Electrochemical Characterization of Halide, Isocyanide, and Alkynyl Synthons Containing the Encumbered Triangular Cluster Unit Pt(3)(mu P(t)Bu(2))(3)

7Useful synthons containing the tribridged triangular unit {Pt3} = [Pt3(μ-PtBu2)3]+ were prepared starting from the known tricarbonyl derivative [{Pt3}(CO)3]Z, [(1+)Z, Z = CF3SO3−]. This was easily converted into the monohalides {Pt3}(CO)2X [2, X = Cl; 3, X = Br; 4, X = I], by reaction with the appropriate halide salt. The coupling reaction between 2 and terminal alkynes in the presence of CuI afforded in good yields the σ-alkynyl derivatives {Pt3}(CO)2(CC-R) [6, R = SiMe3; 7, R = CC-SiMe3; 8, R = C6H5; 9, R = C6H4-4-Br; 10, R = C6H4-4-CCH; 11, R = 2-C4H2S-5-CCH; 12, R = 9-C14H8-10-CCH], while desilylation of 6 or 7 with TBAF/THF gave, respectively, the derivatives 13 (R = H) and 14 (R = CCH). The stepwise elongation of the arylalkynyl chain was obtained by the Sonogashira coupling of 10 with an excess of 1,4-diiodobenzene, which produced 15 (R = C6H4-4-CC-C6H4-4-I), and by coupling the latter with an excess of 1,4-diethynylbenzene, which formed 16 (R = [C6H4-4-CC]3H). Branched synthons were obtained by substitution of the carbonyl ligands with functional isocyanides; the reaction of an excess of CN-C6H4-4-R (R = I, CCH) with {Pt3}(CO)2H, 5, or with complex (1+)Z afforded, respectively, {Pt3}(CN-C6H4-4-I)2H, 17, or [{Pt3}(CN-C6H4-4-R)3]Z [(18+)Z, R = I; (19+)Z, R = CCH]. The crystal structures of complexes 2, 8, and 9 were established by X-ray diffraction studies. The electrochemical characterization of representative examples of the clusters prepared in this work shows that all clusters are characterized by the presence of two oxidations; an analysis of ligands’ effects on the redox processes is also included.reservedmixedCavazza, C.; FABRIZI DE BIANI, Fabrizia; Funaioli, T.; Leoni, P.; Marchetti, F.; Marchetti, L.; Zanello, PieroCavazza, C.; FABRIZI DE BIANI, Fabrizia; Funaioli, T.; Leoni, P.; Marchetti, F.; Marchetti, L.; Zanello, Pier

Ferrocene-based tris(1-pyrazolyl)borates: a new approach to heterooligometallic complexes and organometallic polymers containing transition metal atoms in the backbone.

Starting from mono- and bifunctional ferrocene-based tris(1-pyrazolyl)borates, a novel route to oligonuclear complexes is presented, which incorporates transition metal centers differing substantially in their chemical nature. Both binuclear organometallics FcB(pz)3MLn (Fc:  ferrocenyl. pz:  1-pyrazolyl. MLn:  Tl, 1-Tl; Mo(CO)3Li, 1-MoLi; Mo(CO)2(η3-methylallyl), 1-Mo; ZrCl3, 1-Zr) and trinuclear complexes 1,1‘-fc[B(pz)3MLn]2 (fc:  ferrocenylene. MLn:  Tl, 2-Tl; Mo(CO)3Li, 2-MoLi; Mo(CO)2(η3-methylallyl), 2-Mo) have been prepared. The trinuclear compound [FcB(4-SiMe3pz)3]2Fe, 1-FeSi, has been investigated as a model system for organometallic coordination polymers, consisting of the bifunctional linker 1,1‘-fc[B(pz)3]22- and transition metal ions Mn+. X-ray crystallography shows 1-Tl to establish a polymeric structure in the solid state, while 1-Mo features the usual tridentate coordination mode of the scorpionate ligand (C25H25BFeMoN6O2; a = 8.756(1) Å, b = 12.154(1) Å, c = 12.927(1) Å, α = 105.26(1)°, β = 102.29(1)°, γ = 105.09(1)°; triclinic space group P1̄; Z = 2). With the exception of 1,2-Tl, the anodic oxidation of the ferrocene moiety is generally reversible; cyclic voltammetry measurements indicate the two Mo centers in 2-Mo and the two Fc moieties in 1-FeSi to be noncommunicating

Electron-sink behaviour of the carbonylnickel clusters [Ni32C6(CO)36]6– and [Ni38C6(CO)42]6–: synthesis and characterization of the anions [Ni32C6(CO)36]n– (n = 5–10) and [Ni38C6(CO)42]n– (n = 5–9) and crystal structure of [PPh3Me]6[Ni32C6(CO)36] · 4 MeCN

The hexacarbide clusters [H(6-n)Ni38C6(CO)42](n-) (n = 3, 4, 5, or 6) have been directly obtained from the reaction of [Ni6(CO)12]2- with C3Cl6, whereas the related anions, [H(6-n)-Ni32C6(CO)36](n-) (n = 5 or 6), have been obtained by degradation under carbon monoxide of [Ni38C6(CO)42]6-, or upon thermal treatment at ca. 110 °C of [Ni10C2(CO)16]2- salts. The compound [PPh3Me]6[Ni32C6(CO)36] · 4 MeCN is triclinic, space group P1̄ (No 2), with a = 15.974(3), b = 17.474(3), c = 18.200(4) Å, α = 61.37(2), β = 69.31(2), γ = 72.35(2)°and Z = 1; final R = 0.033. The structure of [Ni32C6(CO)36]6- has an idealised O(h) symmetry and is based on a truncated octahedral Ni32C6 framework, with all edges spanned by bridging carbonyl groups. The six interstitial carbide atoms are lodged in square-antiprismatic cavities. The overall geometry of the Ni32C6 core is very similar to that found previously in [HNi38C6(CO)42]5-, and shows very close interatomic separations. Both [Ni32C6(CO)36]6- and [H(6-n)Ni38C6)(CO)42](n-) (n = 5 or 6) display electron-sink behaviour. Thus, they have been chemically and electrochemically reduced to their corresponding [Ni32C6(CO)36](n-) (n = 7-10), [Ni38C6(CO)42](n-) (n = 7-9) and [HNi38C6(CO)42](n-) (n = 6-8) derivatives, and several of the involved redox changes show features of electrochemical reversibility. In contrast, both [Ni32C6(CO)36]6- and [H(6-n)Ni38C6(CO)42](n-) (n = 5 or 6) support only one partially reversible oxidation step. Their different behaviour upon protonation or oxidation is an indirect, but unambiguous, proof of the hydride nature of [HNi32C6(CO)36]5- and [H(6-n)Ni36C6(CO)42](n-) (n = 3, 4, or 5), which could not be validated by 1H-NMR spectroscopy