The indium(III) halo-bridged octahedral dimers [InX(2)(L-L)(mu-X)(2)InX(2)(L-L)] (X = Cl: L-L = MeS(CH(2))(2)SMe, MeSe(CH(2))(2)SeMe, (n)BuSe(CH(2))(2)Se(n)Bu), the ionic trans-[InX(2)(L-L)(2)][InX(4)] (X = Cl: L-L = (i)PrS(CH(2))(2)S(i)Pr; X = Br: L-L = MeS(CH(2))(2)SMe, (i)PrS(CH(2))(2)S(i)Pr, MeSe(CH(2))(2)SeMe), cis-[InCl(2)(thiamacrocycle)][InCl(4)] (thiamacrocycle = [12]aneS(4) or [14]aneS(4)) and the neutral, octahedral [InCl(3)([9]aneS(3))] and [InCl(3){MeC(CH(2)SMe)(3)}] were obtained in good yield by the reaction of 1:1 molar ratios of InX(3) with the ligand in anhydrous CH(2)Cl(2) solution. The distorted tetrahedral [InX(3)(Me(2)Se)] (X = Cl, Br or I) and [InX(3)(Me(2)Te)] (X = Br or I) were obtained from 1:3 and 1:2 molar ratios respectively of InX(3) and Me(2)E (E = Se or Te) also in CH(2)Cl(2). The ligand-bridged, distorted tetrahedral dimers [(InCl(3))(2){micro(2)-o-C(6)H(4)(CH(2)SMe)(2)}] and [(InCl(3))(2){micro(2)-MeTe(CH(2))(3)TeMe}] are formed even from a 1:1 In:ligand ratio. Key structure types were confirmed from crystal structures of [InCl(2){RSe(CH(2))(2)SeR}(micro-Cl)(2)InCl(2){RSe(CH(2))(2)SeR(2)}] (R = Me or (n)Bu), trans-[InX(2){(i)PrS(CH(2))(2)S(i)Pr}(2)][InX(4)] (X = Cl or Br), trans-[InBr(2){MeSe(CH(2))(2)SeMe}(2)][InBr(4)], cis-[InCl(2)([14]aneS(4))][InCl(4)] and [InBr(3)(Me(2)Se)]. The bulk complexes have been characterised by IR and Raman spectroscopy and microanalyses, while (1)H, (77)Se{(1)H} and (125)Te{(1)H} NMR spectroscopy show that the compounds are extremely labile in solution and undergo rapid dynamic exchange equilibria. Comparisons are drawn between these structurally rather diverse In(III) chalcogenoether complexes and the corresponding Ga(III) species (all of which are neutral and involve distorted tetrahedral coordination). The reaction of TlCl(3) with Me(2)E (E = Se or Te) shows that chlorination of Me(2)E rather than adduct formation occurs, while no reaction occurred between TlCl(3) and Me(2)S, consistent with Tl(III) being a very poor Lewis acid.

The reactions of GaX3 (X = Cl, Br or I) with SMe2, SeMe2 and TeMe2 (L) in non-coordinating solvents produces only the pseudo-tetrahedral [GaX3L], which have been characterised by IR, Raman and multinuclear NMR (1H, 71Ga, 77Se or 125Te) spectroscopy, and by the crystal structure of [GaCl3(SeMe2)]. The 71Ga NMR resonances show small low frequency shifts for fixed halides as the neutral donors change from S --> Se --> Te. Bidentate ligands including MeS(CH2)2SMe, PhS(CH2)2SPh, MeSe(CH2)2SeMe, nBuSe(CH2)2Se(n)Bu and MeTe(CH2)3TeMe (L-L) also produce complexes with 4-coordinate gallium centres, [(GaX3)2(mu-L-L)], confirmed by the crystal structures of [(GaI3)2(mu-MeS(CH2)2SMe)], [(GaCl3)2(mu-PhS(CH2)2SPh)] and [(GaCl3)2(mu-nBuSe(CH2)2Se(n)Bu)]. The structural data are consistent with the weaker Lewis acidity of the gallium as the halide co-ligands become heavier. Multinuclear NMR studies suggest that in chlorocarbon solutions partial dissociation of the ligands occur, which increases with the halide co-ligand Cl < Br < I. The o-xylyl dithioether, o-C6H4(CH2SMe)2, despite being pre-organised for chelation, also forms [(GaCl3)2(mu-L-L)]. The corresponding diselenoether complex decomposes in solution with C-Se bond cleavage to form the selenonium salt [o-C6H4CH2Se(Me)CH2][GaCl4], which was structurally characterised. The ditelluroether o-C6H4(CH2TeMe)2 undergoes rapid C-Te bond fission and rearrangement upon reaction with GaCl3, and the telluronium species [o-C6H4CH2Te(Me)CH2]+ and [MeTe(CH2(o-C6H4)CH2TeMe)2]+ have been identified by ES+ mass spectrometry from their characteristic isotope patterns.

The reaction of RS(CH(2))(2)SR (R = Me, Et or (i)Pr) with NbF(5) produces [NbF(4){RS(CH(2))(2)SR}(2)][NbF(6)] which contain distorted eight-coordinate (dodecahedral) cations and octahedral anions, whereas RSe(CH(2))(2)SeR (R = Me or Bu(n)) form six-coordinate [(NbF(5))(2)(mu-RSe(CH(2))(2)SeR)]. Et(2)S and Me(2)Se (L) also form six-coordinate [NbF(5)(L)], but Me(2)S forms both [NbF(5)(Me(2)S)] and an eight-coordinate cation in [NbF(4)(Me(2)S)(4)][NbF(6)]. MeS(CH(2))(2)SMe forms eight-coordinate cations in [NbX(4){MeS(CH(2))(2)SMe}(2)][NbX(6)] (X = Cl or Br), but other complexes of the heavier halides including [NbX(5)(L)] and [(NbX(5))(2)(mu-L-L)] (L-L = RSe(CH(2))(2)SeR; o-C(6)H(4)(CH(2)SMe)(2) and o-C(6)H(4)(CH(2)SeMe)(2)) contain six-coordinate niobium. The very unstable [NbCl(5)(Me(2)Te)] was characterised spectroscopically, but all other attempts to form telluroether complexes resulted in decomposition, and NbI(5) was reduced even by thioethers. The complexes have been characterised by multinuclear NMR ((1)H, (19)F, (93)Nb, (77)Se or (125)Te), IR and UV/visible spectroscopy, and X-ray crystal structures are reported for [NbF(4){RS(CH(2))(2)SR}(2)][NbF(6)] (R = Me, (i)Pr), [NbF(4)(Me(2)S)(4)][NbF(6)], [NbCl(5)(Me(2)Se)], [NbBr(5)(Me(2)S)], [(NbCl(5))(2){o-C(6)H(4)(CH(2)SMe)(2)}] and [(NbCl(5))(2){MeSe(CH(2))(2)SeMe}]. All the complexes are very moisture sensitive and the fluoride complexes decompose slowly with fluorination of the neutral ligand.

The highly unusual Mo(VI) thioether complexes [MoO(2)X(2)(L-L)][space](X = Cl or Br; L-L = MeS(CH(2))(2)SMe or EtS(CH(2))(2)SEt) were obtained by reaction of MoO(2)X(2) with L-L in rigorously anhydrous CH(2)Cl(2) solution. Similar reaction of MoO(2)Cl(2) with the diselenoether MeSe(CH(2))(2)SeMe gives the very reactive [MoO(2)Cl(2)[MeSe(CH(2))(2)SeMe]] as a yellow solid. These compounds are very moisture sensitive and were characterised by IR, diffuse reflectance UV-vis and multinuclear ((1)H, (13)C[(1)H], (77)Se and (95)Mo) NMR spectroscopy. The data are consistent with distorted 6-coordination at Mo(vi)viatrans X ligands, mutually cis oxo groups and a chelating dithio- or diseleno-ether ligand. Variable temperature (1)H and (13)C[(1)H] NMR data indicate fast pyramidal inversion at the coordinated chalcogen atoms occurs at room temperature, but cooling slows this process to reveal resonances consistent with the meso and dl forms. The (95)Mo NMR spectra are single resonances in the region 200-300 ppm, as expected for Mo(vi) complexes, and show inverse dependence of the chemical shifts upon both halide and chalcogen type. Crystal structures of three of the dithioether complexes are described and provide unequivocal evidence for Mo(vi) thioether coordination, confirming chelation of the dithioether through long Mo-S interactions of ca. 2.7 [Angstrom]. Attempts to extend the range of compounds by using other chalcogenoether ligands failed, indicating that to obtain complexes involving these extremely mis-matched metal ligand combinations requires both the favourable 5-membered chelate ring and small terminal alkyl substituents on the chalcogen.

The ligands o-C(6)H(4)(CH(2)EMe)(2) (E = S or Se) have been prepared and characterised spectroscopically. A systematic study of the coordination chemistry of these, together with the telluroether analogue, o-C(6)H(4)(CH(2)TeMe)(2), with late transition metal centers has been undertaken. The planar complexes [MCl(2){o-C(6)H(4)(CH(2)SMe)(2)}] and [M{o-C(6)H(4)(CH(2)EMe)(2)}(2)](PF(6))(2) (M = Pd or Pt; E = S or Se), the distorted octahedral [RhCl(2){o-C(6)H(4)(CH(2)EMe)(2)}(2)]Y (E = S or Se: Y = PF(6); E = Te: Y = Cl) and [RuCl(2){o-C(6)H(4)(CH(2)EMe)(2)}(2)] (E = S, Se or Te), the dithioether-bridged binuclear [{RuCl(2)(p-cymene)}(2){micro-o-C(6)H(4)(CH(2)SMe)(2)}] and the tetrahedral [M'{o-C(6)H(4)(CH(2)EMe)(2)}(2)]BF(4) (M' = Cu or Ag; E = S, Se or Te) have been obtained and characterised by IR and multinuclear NMR spectroscopy ((1)H, (63)Cu, (77)Se{(1)H}, (125)Te{(1)H} and (195)Pt), electrospray MS and microanalyses. Crystal structures of the parent o-C(6)H(4)(CH(2)SMe)(2) and seven complexes are described, which show three different stereoisomeric forms for the chelated ligands, as well as the first example of a bridging coordination mode in [{RuCl(2)(p-cymene)}(2){micro-o-C(6)H(4)(CH(2)SMe)(2)}]. These studies reveal the consequences of the sterically demanding o-xylyl backbone, which typically leads to unusually obtuse E-M-E chelate angles of approximately 100 degrees .