Atomically Precise Ni-Pd Alloy Carbonyl Nanoclusters: Synthesis, Total Structure, Electrochemistry, Spectroelectrochemistry, and Electrochemical Impedance Spectroscopy

The molecular nanocluster [Ni36-xPd5+x(CO)46]6- (x = 0.41) (16-) was obtained from the reaction of [NMe3(CH2Ph)]2[Ni6(CO)12] with 0.8 molar equivalent of [Pd(CH3CN)4][BF4]2 in tetrahydrofuran (thf). In contrast, [Ni37-xPd7+x(CO)48]6- (x = 0.69) (26-) and [HNi37-xPd7+x(CO)48]5- (x = 0.53) (35-) were obtained from the reactions of [NBu4]2[Ni6(CO)12] with 0.9-1.0 molar equivalent of [Pd(CH3CN)4][BF4]2 in thf. After workup, 35- was extracted in acetone, whereas 26- was soluble in CH3CN. The total structures of 16-, 26-, and 35- were determined with atomic precision by single-crystal X-ray diffraction. Their metal cores adopted cubic close packed structures and displayed both substitutional and compositional disorder, in light of the fact that some positions could be occupied by either Ni or Pd. The redox behavior of these new Ni-Pd molecular alloy nanoclusters was investigated by cyclic voltammetry and in situ infrared spectroelectrochemistry. All three compounds 16-, 26-, and 35- displayed several reversible redox processes and behaved as electron sinks and molecular nanocapacitors. Moreover, to gain insight into the factors that affect the current-potential profiles, cyclic voltammograms were recorded at both Pt and glassy carbon working electrodes and electrochemical impedance spectroscopy experiments performed for the first time on molecular carbonyl nanoclusters

Diastereoselective additions of organometallic reagents to (SFc)-2-p-tolylsulfanylferrocene carboxyaldehyde and to (SFc)-2-p-tolylsulfanyl ferrocenyl imines. Synthesis of new central and planar chiral ferrocenyl alcohols and amines

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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

Peripheral halo-functionalization in [Cu(N^N)(P^P)]+ emitters: influence on the performances of light-emitting electrochemical cells

A series of heteroleptic [Cu(N^N)(P^P)][PF6] complexes is described in which P^P = bis(2-(diphenylphosphino)phenyl)ether (POP) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos) and N^N = 4,4′-diphenyl-6,6′-dimethyl-2,2′-bipyridine substituted in the 4-position of the phenyl groups with atom X (N^N = 1 has X = F, 2 has X = Cl, 3 has X = Br, 4 has X = I; the benchmark N^N ligand with X = H is 5). These complexes have been characterized by multinuclear NMR spectroscopy, mass spectrometry, elemental analyses and cyclic voltammetry; representative single crystal structures are also reported. The solution absorption spectra are characterized by high energy bands (arising from ligand-centred transitions) which are red-shifted on going from X = H to X = I, and a broad metal-to-ligand charge transfer band with λmax in the range 387–395 nm. The ten complexes are yellow emitters in solution and yellow or yellow-orange emitters in the solid-state. For a given N^N ligand, the solution photoluminescence (PL) spectra show no significant change on going from [Cu(N^N)(POP)]+ to [Cu(N^N)(xantphos)]+; introducing the iodo-functionality into the N^N domain leads to a red-shift in λmaxem compared to the complexes with the benchmark N^N ligand 5. In the solid state, [Cu(1)(POP)][PF6] and [Cu(1)(xantphos)][PF6] (fluoro-substituent) exhibit the highest PL quantum yields (74 and 25%, respectively) with values of τ1/2 = 11.1 and 5.8 μs, respectively. Light-emitting electrochemical cells (LECs) with [Cu(N^N)(P^P)][PF6] complexes in the emissive layer have been tested. Using a block-wave pulsed current driving mode, the best performing device employed [Cu(1)(xantphos)]+ and this showed a maximum luminance (Lummax) of 129 cd m−2 and a device lifetime (t1/2) of 54 h; however, the turn-on time (time to reach Lummax) was 4.1 h. Trends in performance data reveal that the introduction of fluoro-groups is beneficial, but that the incorporation of heavier halo-substituents leads to poor devices, probably due to a detrimental effect on charge transport; LECs with the iodo-functionalized N^N ligand 4 failed to show any electroluminescence after 50 h

Topological insights in polynuclear Ni/Na coordination clusters derived from a schiff base ligand

This article presents the syntheses, crystal structures, topological features and magnetic properties of two NiII/NaI coordination clusters (CCs) formulated [NiII3Na(L1)3(HL1 (MeOH)2] (1) and [NiII6Na(L1)5(CO3)(MeO (MeOH)3(H2O)3]·4(MeOH) 2(H2O) [2 4(MeOH) 2(H2O)] where H2L1 is the semi rigid Schiff base ligand (E)-2-(2-hydroxy-3 methoxybenzylideneamino)-phenol). Compound 1 possesses a rare NiII3NaI cubane (3M4-1) topology and compound 2 is the first example in polynuclear Ni/Na chemistry that exhibits a 2,3,4M7-1 topology

Dinuclear [Cu2(N^N)(P^P)2][PF6]2 complexes containing bridging 2,3,5,6-tetra(pyridin-2-yl)pyrazine or 2,4,6-tri(pyridin-2-yl)-1,3,5-triazine ligands

The dinuclear copper(I) complexes [Cu2(1)(POP)2][PF6]2, [Cu2(2)(POP)2][PF6]2, [Cu2(1)(xantphos)2][PF6]2 and [Cu2(2)(xantphos)2][PF6]2 containing bridging 2,3,5,6-tetra(pyridin-2-yl)pyrazine (1) or 2,4,6-tri(pyridin-2-yl)-1,3,5-triazine (2) ligands and the P^P ligands bis(2- (diphenylphosphino)phenyl)ether (POP) or 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (xantphos) are presented. The single crystal structures of [Cu2(1)(POP)2][PF6]2 and [Cu2(2)(POP)2][PF6]2 confirm that both 1 and 2 act as bis(bidentate) ligands, bridging between two copper(I) centres; in [Cu2(1)(POP)2][PF6]2, two pyridine rings are non-coordinating, and in [Cu2(2)(POP)2][PF6]2, there is one non-coordinating pyridine. In solution and on the NMR timescale at 295 K, the four pyridine rings in coordinated 1 are equivalent; similarly, the three pyridine donors in the [Cu2(2)(P^P)2][PF6]2 complexes are equivalent. The dynamic behaviour of [Cu2(2)(POP)2][PF6]2 and [Cu2(2)(xantphos)2][PF6]2 are investigated using variable temperature 1H NMR spectroscopy. The photophysical properties of the complexes are discussed

Capitolo 25: Composti di Coordinazione

This textbook shows a strong emphasis on fundamental skills and concepts. As in previous editions, clearly explained problem-solving strategies continue to be the strength of this student-friendly text. This revision builds on the highly praised style and applications to everyday life that have earned this text a reputation as the voice of authority in general chemistry. Whitten always has been viewed as one of the few truly "traditional" general chemistry texts. Examples of this are that the text covers Thermodynamics, normally a topic split into two parts and covered in two different semesters, in one chapter and begins the second half of the course. GENERAL CHEMISTRY, Seventh Edition also follows a standard narrative-example-problem format, has a solid traditional writing style, and promotes problem solving. However, the authors have added some new elements over the years to reflect changes in chemical education. These include adding in conceptual questions in the problem sets, adding features like the Chemistry In Use boxes to show how chemistry is used in daily life, and further promoting problem solving by including hints and checks for students