Dennis G. Tuck

Direct Electrochemical Synthesis of Inorganic and Organometallic Compounds

The method of direct electrochemical synthesis consists of oxidizing a metal anode in a non-aqueous solution containing a ligand (or ligand precursor) to produce the appropriate inorganic or organometallic compound. In many cases, the product precipitates directly in the cell, making for easy isolation, so that the technique is both direct and simple, and in addition the product yields are very high. One advantage of the technique is that the products are often derivatives of a low oxidation state of the metal; \examples of this include chromium(III) bromide, tin(II) and lead(II) diolates and thiolates, hexahalogenodigallate(II) anions, thorium diiodide, copper(I) thiolate complexes, and indium(I) derivatives of thiols, dithiols, and diols. In some systems, the low oxidation state compound undergoes subsequent reaction; for example, in the synthesis of RInX2 the reaction sequence involves the oxidation of indium metal to give InX, which then reacts with RX to give RInX2. Another possible post-electrolysis process is disproportionation. Examples of these various preparative routes will be discussed.

DIRECT ELECTROCHEMICAL SYNTHESIS OF SOME METAL CHELATE COMPLEXES

Abstract A convenient electrochemical synthesis of various ML2, ML3, ML4 and MOL2 complexes (M = Ti, Zr,Hf, V,Cr, Mn,Fe, Co,Ni, Cu,In; L = acetylacetonate anion, 3-hydroxy-2-methyl-4-pyronate anion, 2-acetylpyrrolate anion, and other bidentate ligands) is described. The metal, as the anode of simple cell, is oxidised in the presence of the parent compound of the ligand (HL) in an organic solvent mixture. Gram quantities of complex can be produced in a few hours; other advantages of this method are discussed. Current efficiency measurements serve to identify the reaction mechanism.

The coupling of organic groups by the electrochemical reduction of organic halides: Catalysis by 2,2′-bipyridinenickel complexes

Abstract The electrochemical reduction of a dilute solution of NiX 2 bipy (bipy = 2,2′-bipyridine) in N -methylpyrrolidone gives the corresponding Ni 0 complex, which undergoes oxidative addition with an excess of an organic halide RX to form RNiX. Decomposition of RNiX gives the dimer R 2 in good yield and nickel(II). The nickel(0) species is regenerated to give an electrocatalytic process. The possible mechanism of these reactions is discussed briefly.

The direct electrochemical synthesis of some thiolates of zinc, cadmium and mercury

Abstract The electrochemical oxidation of anodic Zn, Cd or Hg (M) into acetonitrile solutions of RSH (or R 2 S 2 ) gives the corresponding M(SR) 2 compounds in high yield. The mechanism of the electrochemical reactions is discussed. The insolubility, and the far infrared spectra (500–50 cm −1 ), are compatible with a polymeric structure for M(SR) 2 in the solid state.

The direct electrochemical synthesis and crystal structure of salts of [M4(SC6H5)10]2− anions (M = Zn, Cd)

Abstract The salts [(C2H5)3NH]2[M4(SC6H5)10] (M = Zn, Cd) can be prepared by the electrochemical oxidation of the metal in an acetonitrile solution of triethylamine and benzenethiol. An X-ray crystal structure determination shows that the anion consists of a tetrahedron of metal atoms, each carrying a terminal -SC6H5 ligand, and connected to the three other metal atoms by bridging > SC6H5 groups. The results are compared with those for similar compounds reported in the literature.

Electrochemical preparation and structure of an unusual zinc(II) thiolato anionic cluster

The electrochemical oxidation of anodic zinc into a solution of PhSH + Et3N in CH3CN yields *Et3NH)2[Zn4(SPh)10]. The structure, as determined by X-ray crystallography, shows that the anion is a novel cluster based on a tetrahedral Zn4S10 kernel.

The electrochemical synthesis of neutral and anionic organozinc halides

A series of 2,2′-bipyridine adducts of organozinc(II) halides RZnX has been prepared by the electrochemical oxidation of zinc in the presence of organic solutions of RX (R  CH3, C2H5, CF3, C3H3, C6H5, C6H5CH2; X  Cl, Br, I (not all combinations)). Similar methods have been used to prepare the anions RZnX2 (R  CH3, C2H5, C6H5, CF3; X  Cl, Br, I (not all combinations)) as the tetra-n-propylammonium salts.

One-electron transfer reactions in the redox chemistry of main group compounds

A. Introduction B. M-M bonded compounds C. Oxidative addition reactions of indium(1) compounds. .. D. Quinones as oxidants for Main Group species ....... (i) Reactions of InX or SnX, with o-quinones. ...... (ii) The oxidation of non-metallic compounds ....... (iii) Oxidation of metallic and non-metallic elements ... E. Conclusions Acknowledgement References . . . . . . .

The direct electrochemical synthesis of zinc and cadmium catecholates and related compounds

Abstract The electrochemical oxidation of either zinc or cadmium (= M) in acetone solutions of o -C 6 H 4 (OH) 2 (= R(OH) 2 ) gives M(O 2 R) in good yield. The advantages of this method are discussed. When neutral mono- or bidentate donors are present in the solution, the products are the 1:2 or 1:1 adducts of M(O 2 R). Similar results ar reported for 2,3-dihydroxynaphthalene and 2,2′dihydroxybiphenyl. A preliminary crystal structure determination on Zn(O 2 C 6 H 4 )(phen) 2 ·2C 6 H 4 (OH) 2 (phen) = 1.10-phenanthroline) shows the presence of a ZnO 2 N 4 kernel; each oxygen atom of the catecholate ligand is hydrogen-bonded to both hydrogens of a neutral C 6 H 4 (OH) 2 molecule.

The crystal structure of indium diiodide, indium(I) tetraiodoindate(III), In[InI4]

Abstract The crystal structure of the title compound has been determined by the heavy atom method. The crystals are orthorhombic, space group Pnna , with unit cell dimensions a = 8.525(5) A, b = 10.969(9) A, c = 11.162(8) A, Z = 4; R = 0.043 for 807 unique ‘observed’ reflections. The structure consists of InI 4 − anions (r(nI-I) = 2.714 A (av.)) and In + cations. A value is derived for the ionic radius of In + . Indium dichloride is not isomorphous with In[Inl 4 ].