Pyridine-copper tetramers

Recently, we have proposed a methodology [71] similar to the last approach, but using semiempirical molecular orbital methods instead of TDHE methods, to calculate the frequency-dependent polarizability properties of the molecule-surface complex. Although this is a lower level description of the electronic structure, the use of semiempirical methods allows us to describe more complex molecules than has been considered in earlier studies. In the following, we present some recent results for the pyridine-copper tetramer system, and we examine the influence of molecule-metal distance on the Raman intensities for this model. There are two components to the calculation of the Raman intensity (1) calculation of the ground state structure and normal coordinates and (2) calculation of the derivative of the frequency-dependent... 

The oxidation of halo(pyridine)copper(I) complexes by O2 in CH2CI2 and nitrobenzene also proceeds with an overall 4 1 stoichiometry, producing tetranuclear oxocopper(II) complexes. The kinetic behavior is governed by the involvement of Cu(I) in a monomer-dimer-tetramer equilibrium. 

Work by Paul Beer et al. in Oxford on dithiocarbamate-functionalised resorcarenes has resulted in resorcarene trimers termed molecular loops and molecular tetrahedra composed of four resorcarene units. The molecular loops (pyridine-capped Cd(II) and Zn(II) complexes) can bind C60 which fits neatly into the 16.4 A wide central cavity.35 The slightly larger tetrahedral tetramer which has a 19.4 A edge length, compared to 19.1 A for the loop, is bridged by square planar copper(III) ions, a very unusual oxidation state of copper that is obtained from iodine oxidation of an intermediate copper(II) complex. The solid-state structures of examples of the loop and tetrahedron are shown in Figure 10.35. 

Copper(I) Carboxylates, Triflate, Alkoxides, and Dialky lamides. Thecarbox-ylates have varied structures. The acetate that is obtained as white air-sensitive crystals by reduction of Cu11 acetate by Cu in pyridine or MeCN has a planar chain structure (17-H-I). By contrast the trifluoroacetate [Cu02CCF3]4-2C,H6, and benzoate [Cu02CPh]4 complexes are tetramers with bridging carboxylates as in (17-H-II). This is only one type of Cut polynuclear structure (see later). There are also bridged pyrazole and pyrazolylborate compounds. 

Oxidative coupling of 1,5-hexadiyne (150) with copper(ii) acetate in pyridine yielded a mixture of the cyclic trimer 151, the tetramer 152, the pentamer 153 and the hexamer 154 in addition to other compounds - The cyclic trimer 151... 

C2oH2oCUftI4N4, Copper(I) iodide - pyridine tetramer, 42B, 849 C20H2oi2NaNi, Diiodotetrakis(pyridine)nickel(II), 39B, 750 C20H20MO2N4O8P2 f Di-M oxo-bis(2,2 -bipyridyloxohypophosphitomolyb-denum(V)), 42B, 914... 

Photoexcitation (X = 313 nm) of the charge-transfer adducts of N with CuBr(Py)(PPh3) or Cu[HB(Pz)3] in hexane (Py = pyridine, Pz = 1-pyrazolyl) gives rise to Q with = 0.37-0.65. The photorearrangement of the complexes of N with halo(ferrocenyl-diphenylphosphine)copper(I) tetramers... 

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