Theodore A. Annan

The properties and structures of tris(benzenethiolato)indium(III)-bis-pyridine adduct, and of tris(benzeneselenolato)indium(III)

Abstract The bis-pyridine adduct of In(SC6H5)3 has been prepared. A crystal structure determination shows that the molecule has two different conformations in the solid state, related to the orientations of the phenyl rings of the SC6H5 ligand. The crystalline form of In(SeC6H5)3 is a homopolymer in which six-coordinate indium atoms are linked through bridging selenium atoms. The phenyl groups of the SeC6H5 ligand show an interesting disorder pattern. The structure of In(SC6H5)3 is discussed in this context.

One-electron transfer processes in the reaction of tin(II) halides with substituted o-quinones; crystal structure of bis(3,5-di-t-butylcatecholato)tin–1,10-phenanthroline–dimethylformamide (1/1/2)

The reaction of SnX2(X = Cl, Br, or I) with 3,5-di-t-butl-1,2-benzoquinone or phenanthrene-9,10-quinone in the presence of 2,2′-bipyridine (bipy) or 1,10-phenanthroline gives the adducts of the appropriate SnX2(diolate) formed by oxidative addition. Various spectroscopic results (i.r., 1H, 13C n.m.r.) confirm the conversion of o-quinone into the corresponding catecholate. E.s.r. studies show that semiquinone derivatives are intermediates in these processes, and a mechanism is proposed to satisfy both preparative and e.s.r. results in terms of two successive one-electron-transfer processes. The crystal structure of bis(3,5-t-butylcatecholato)tin(IV)–1,10-phenanthroline–dimethylformamide (1/1/2) has been determined by X-ray crystallography using the heavy-atom method. Crystal parameters are triclinic, space group P, a= 10.761(2), b= 14.357(3), c= 15.361(4)A, α= 93.5(3), β= 95.8(2), γ= 94.8(3)°, and Z= 2. The structure analysis, based on 3 005 observed reflections [I > 2σ(I)] gave R= 0.0699. The average Sn–O distance [2.008(8)A] is typical of tin(IV) compounds and the average C–O distance [1.36(1)A] again confirms that the ligand is an aromatic 1,2-diolate.

The direct electrochemical synthesis of metal–diphenylphosphido complexes, and the crystal structure of Cu4(µ-PPh2)4(Ph2PCH2PPh2)2

The electrochemical oxidation of metal anodes in an acetonitrile solution of Ph2PH yields M(PPh2)(M = Cu, Ag, Au) or M(PPh2)2(M = Co, Zn, Cd); with a solution of Ph2PH and bis(diphenylphosphino)methane (dppm), this method gives Cu4(PPh2)4(dppm)2 whose structure is found to be very similar to that of Cu4(SC5H11)4(dppm)2.

Indium(III) halide-3,5-di-tert-butyl-o-benzosemiquinone systems

Abstract The reaction of InX3 (X  Cl, Br, I) with 2 mol of Na+TBSQ·− (TBSQ·− =3,5-di-t-butyl-o-benzosemiquinonate anion) yields solutions of the diradicals InX(TBSQ)2, whose EPR spectra have been recorded. Addition of pyridine or γ-picoline (L) to such solutions produces adducts of the 3,5-di-t-butylcatecholate-indium(III) halide, of the type In(TBC)XLn. The mechanism of these reactions, and of the related ligand replacement and disproportionation equilibria, is discussed in terms of internal one-electron transfer processes. The compound In(TBC)(pic)2·DMF has been the subject of an X-ray crystallographic study. The substance forms monoclinic crystals, space group P21/n with a=12.992(5), b=13.923(4), c=18.491(4) A, β=98.82(2)o, Z=4, R=0.053 for 3244 unique reflections. The molecule is dimeric, with a central In2O2 ring, involving six-coordinate indium(III).

The insertion of indium(I) halides into the MX bond of some main group organometallic halides

Abstract Indium(I) halides (InX) react with Ph 3 SnX (X = Cl, Br, I) in toluene/tmed mixtures to give Ph 3 SnInX 2 ·tmed compounds (tmed = N , N , N′ , N′ -tetramethylethanediamine), and Ph 3 Sn(OAc) yields Ph 3 SnIn(OAc)X 2 ·tmed. Vibrational spectra and conductivities of these compounds, and of the salt Et 4 N[Ph 3 SnInCl 3 ], show that these are the first examples of SnIn bonded molecules. With Me 3 SnCl, Ph 3 SnH, Ph 3 GeCl, Ph 3 PbCl and Ph 2 PCl, no oxidative addition reaction was observed. The results are compatible with previous discussions of the mechanism of such reactions, based on the insertion of indium into the MX bond.

Electrochemical oxidation of elemental indium in liquid ammonia media

The electrochemical oxidation of indium metal in solutions of NH4X (X = Cl, Br or I) in liquid ammonia proceeds with an electrochemical efficiency which implies the formation of indium(II) species at the anode. In the case of NH4I–NH3, Raman spectroscopy confirmed the presence of In2I4 in solution; it was not possible to isolate neutral or anionic derivatives of indium(II), since disproportionation occurs on removal of solvent to give indium-(0), -(I) and -(III) derivatives. Mass-balance experiments have been made for these systems. Solutions of NH4I + substituted o-quinone (But2H2C6O2-o or Br4C6O2-o) yielded InI3·3NH3, while with substituted catechols [X4C6(OH)2; X = Cl or Br] the products were [NH4]3[In(O2C6X4)3]·Et2O. In the case of a solution of But2H2C6(OH)2-o(H2dbc) in liquid NH3–Et2O media, the final product is a derivative of the dimeric anion [In2(dbc)4(NH3)2]2–, in a lattice which also contains NH4+, Hdbc– and Et2O. The crystal parameters of [NH4]4[In2(dbc)4(NH3)2]·(2Hdbc)·2Et2O are monoclinic, space group P21/n, a= 14.464(10), b= 19.194(5), c= 19.560(7)A, β= 103.72(4)°, Z= 4, R= 0.055. The anion involves two InO5N kernels, with In2O2 cross-linking responsible for the dimerization.

The reaction of some substituted ortho-benzoquinones with elemental tellurium and with tellurium(II) compounds

The oxidation of elemental tellurium by three ortho-benzoquinones (RO2: R = Cl4C6, Br4C6 or 3,5-But2H2C6) is a direct route to the corresponding tellurium(IV) catecholates Te(O2R)2. The analogous reaction with organotellurium(II) TeR′2[R′= Me2, Et2, Ph(Et) or Ph(Br)] gives the products Te(O2R)R′2. The reactions proceed in each case by one-electron transfer, since the presence of the semiquinone radical RO2˙ in the reaction mixture has been demonstrated by ESR spectroscopy. The Te(O2R)2 species resist further oxidation, and also show weak donor and acceptor properties. The structure of the compound Te(O2C6H2But2-3,5)2(bipy)1(bipy = 2,2′-bipyridine) has been determined by X-ray crystallography. Crystal parameters: triclinic, space group P, a= 10.388(2), b= 14.468(3), c= 15.820(3)A, α= 106.00(1), β= 115.98(2), γ= 94.98(2)°, Z= 2 and R= 0.0424 for 3424 reflections. For Te(O2C6Cl4)·18-crown-6 2(18-crown-6 = 1,4,7,10,13,16-hexaoxacyclooctadecane), the crystal parameters are: monoclinic, space group P21/n, a= 10.809(4), b= 18.571(7), c= 19.287(9)A, β= 91.53(4)°, Z= 4 and R= 0.057 for 3768 reflections. In 1 the bipy is co-ordinated by weak Te–N interactions, with clear evidence for a stereochemically active lone pair, while in 2 the cryptand ring is situated around the axis of the presumed lone pair.

Studies of the oxidation of elemental phosphorus by substituted ortho-benzoquinones

The phosphorus compounds P(O2C6R)2Br (R = Cl4, Br4 or Bu2H2) have been prepared by the reaction of P4, Br2 and the substituted o-benzoquinone RC6O2-o. There is no reaction between Bu2H2C6O2-o, P4 and Ph2Se2, but in the presence of catalytic quantities of Br2 the product is P(O2C6H2Bu2)2(SePh). ESR spectra identify the presence of the corresponding o-semiquinone species in these reactions. The 13C and 31P NMR spectra of these phosphoranes are reported, and compared with those of P(O2C6R)X3(X3= Ph3, Ph2Cl, Br3 or Cl3) prepared by the reaction of PX3 and RC6O2-o.