Structural and spectroscopic trends in mononuclear arylchalcogenolato-palladium(II) and -platinum(II) complexes: Crystal structures of [M(TeAr)2(dppe)] {M = palladium, platinum; Ar = phenyl, 2-thienyl; dppe = 1,2-bis(diphenylphosphino)ethane}

A series of mononuclear [M(EAr)₂(dppe)] [M = Pd, Pt; E = Se, Te; Ar = phenyl, 2-thienyl; dppe = 1,2-bis(diphenylphosphino)ethane] complexes has been prepared in good yields by the reactions of [MCl₂(dppe)] and corresponding ArE⁻ with a special emphasis on the aryltellurolato palladium and -platinum complexes for which the existing structural information is virtually non-existent. The complexes have crystallized in five isomorphic groups: (1) [Pd(SePh)₂(dppe)] and [Pt(SePh)₂(dppe)], (2) [Pd(TePh)₂(dppe)] and [Pt(TePh)₂(dppe)], (3) [Pd(SeTh)₂(dppe)], (4) [Pt(SeTh)₂(dppe)] and [Pd(TeTh)₂(dppe)], and (5) [Pt(TePh)₂(dppe)]. In addition, solvated [Pd(TePh)₂(dppe)] · CH₃OH and [Pd(TeTh)₂(dppe)] · 1/2CH₂Cl₂ could be isolated and structurally characterized. The metal atom in each complex exhibits an approximate square-planar coordination. The Pd-Se, Pt-Se, Pd-Te, and Pt-Te bonds span a range of 2.4350(7)-2.4828(7) Å, 2.442(1)-2.511(1) Å, 2.5871(7)-2.6704(8) Å, and 2.6053(6)-2.6594(9) Å, respectively, and the respective Pd-P and Pt-P bond distances are 2.265(2)-2.295(2) Å and 2.247(2)-2.270(2) Å. The orientation of the arylchalcogenolato ligands with respect to the M(E₂)(P₂) plane has been found to depend on the E-M-E bond angle. The NMR spectroscopic information indicates the formation of only cis-[M(EAr)₂(dppe)] complexes in solution. The trends in the ³¹P, ⁷⁷Se, ¹²⁵Te, and ¹⁹⁵Pt chemical shifts expectedly depend on the nature of metal, chalcogen, and aryl group. Each trend can be considered independently of other factors. The ⁷⁷Se or ¹²⁵Te resonances appear as second-order multiplets in case of palladium and platinum complexes, respectively. Spectral simulation has yielded all relevant coupling constants.     

Ortho-tellurated derivatives of some arylamines and imines

A range of novel bi-, tri- and multidentate organotellurium ligands containing Te and N donor atoms and their derivatives have been synthesised. The synthetic strategy involves telluration of orthochelating, monoanionic substrates derived from the following arylamines: N,N-dimethylbenzylamine, (S)-(-)-N,Ndimethyl-1-phenethylamine, N,N-dimethylnaphthylamine, (N,N-di-methylaminomethy l) ferrocene, tricarbony1(N, N-dimethylbenzenemethanamine) chromium and 2-(3-thienyl)-pyridine. In addition novel chiral hybrid Schiff base ligands have been prepared by the condensation reaction of bis(o-formylphenyl) telluride ando-butyltellurobenzaldehyde with (R)-(+)-l-phenethylamine and (1R, 2S)-(-)-norephedrine.     

Structures of Iodophenyltellurium(II) and Diiododi-(β-naphtyl)tellurium(IV)

The reactions between diphenyl ditelluride, (PhTe)₂, or di(β-naphtyl)ditelluride, (β-naphtylTe)₂, with equivalent amounts of iodine have been reinvestigated and the crystal and molecular structures of iodophenyltellurium(II), (PhTeI)₄, and diiododi-(β-naphtyl)tellurium(IV), (β-naphtyl)₂TeI₂, have been determined. The structure of iodophenyltellurium(II) (space group Cc, a = 13.850(5) Å, b = 13.852(3) Å, c = 16.494(6) Å and β = 101.69(2)°, Z = 4) is built up by four PhTeI units which are linked by weak Te–Te interactions with Te–Te distances between 3.152(5) Å and 3.182(4) Å. The angles between the tellurium atoms are approximately 90° giving an almost perfect square. Long range secondary bonds (Te–I: about 4.2 Å) link the tetrameric units to give an infinite two-dimensional network. Iodo(β-naphtyl)tellurium(II) is less stable than the phenyl derivative. Solutions of this compound decompose under formation of elemental tellurium and (β-naphtyl)₂TeI₂. (β-Naphtyl)₂TeI₂ crystallises in the monoclinic space group C 2/c (a = 21.198(6) Å, b = 5.8921(8) Å, c = 16.651(5) Å, β = 114.77(2)°). The tellurium atom is situated on a two-fold crystallographic axis and Te–I and Te–C bond lengths of 2.899(1) and 2.108(7) Å have been determined.     

New versatile organyltellurium(IV) halides: Synthesis and X-ray structural features of the telluronium tellurolate salts [PhTe(CH3)2]2[TeX6] (X = Cl, Br) and [Ph3Te][PhTeX4] (X = Cl, Br, I)

TeX₄ (X = Cl, Br) react in HCl/HBr with [Ph(CH₃)₂Te]X (X = Cl, Br) to give [PhTe(CH₃)₂]₂[TeCl₆] (1) and [PhTe(CH₃)₂]₂[TeBr₆] (2). The reaction of PhTeX₃ (X = Cl, Br, I) in cooled methanol with [(Ph)₃Te]X (X = Cl, Br, I) leads to [Ph₃Te][PhTeCl₄] (3), [Ph₃Te][PhTeBr₄] (4) and [Ph₃Te][PhTeI₄] (5). In the lattices of the telluronium tellurolate salts 1 and 2, octahedral TeCl₆ and TeBr₆ dianions are linked by telluronium cations through Te?Cl and Te?Br secondary bonds, attaining bidimensional (1) and three-dimensional (2) assemblies. The complexes 3, 4 and 5 show two kinds of Te?halogen secondary interactions: the anion-anion interactions, which form centrosymmetric dimers, and two identical sets of three telluronium-tellurolate interactions, which accomplish the centrosymmetric fundamental moiety of the supramolecular arrays of the three compounds, with the tellurium atoms attaining distorted octahedral geometries. Also phenyl C-H?halogen secondary interactions are structure forming forces in the crystalline structures of compounds 3, 4 and 5.     

Synthesis and spectroscopic characterization of eleven mixed-ligand diorganotellurium(IV) compounds containing dithiocarbamate and dithiophosphate ligands

Eleven mixed-ligand organotellurium(IV) compounds of composition R₂Te(dtc)(dtp) have been prepared employing two different dithiocarbamate (dtc) and dithiophosphate (dtp) ligands: 1, R₂ = C₄H₈, dtc = S₂CNEt₂, dtp = S₂P(OCH₂)₂CEt₂; 2, R₂ = C₈H₈, dtc = S₂CNEt₂, dtp = S₂P(OCH₂)₂CEt₂; 3, R₂ = C₄H₈O, dtc = S₂CNEt₂, dtp = S₂P(OCH₂)₂CEt₂; 4, R₂ = C₅H₁₀, dtc = S₂CNEt₂, dtp = S₂P(OCH₂)₂CEt₂; 5, R₂ = C₄H₈, dtc = S₂CN(CH₂)₄, dtp = S₂P(OCH₂)₂CEt₂; 6, R₂ = C₈H₈, dtc = S₂CN(CH₂)₄, dtp = S₂P(OCH₂)₂CEt₂; 7, R₂ = C₄H₈O, dtc = S₂CN(CH₂)₄, dtp = S₂P(OCH₂)₂CEt₂; 8, R₂ = C₅H₁₀, dtc = S₂CN(CH₂)₄, dtp = S₂P(OCH₂)₂CEt₂; 9, R₂ = C₄H₈, dtc = S₂CN(CH₂)₄, dtp = S₂P(OCH₂)₂CMeⁿPr; 10, R₂ = C₈H₈, dtc = S₂CN(CH₂)₄, dtp = S₂P(OCH₂)₂CMeⁿPr; 11, R₂ = C₄H₈O, dtc = S₂CN(CH₂)₄, dtp = S₂P(OCH₂)₂CMeⁿPr. 1-11 were characterized by mass spectrometry, IR spectroscopy and multinuclear NMR (¹H, ¹³C, ³¹P, ¹²⁵Te) spectroscopy. The molecular structures of 2, 4 and 6, of which 2 crystallized in form of two different polymorphs (2a and 2b), were analyzed by single-crystal X-ray diffraction analysis. This analysis showed that the coordination mode of both ligand types is anisobidentate. When considering only covalent Te-C and Te-S bonds, the coordination geometry of the tellurium atoms is distorted Ψ-trigonal-bipyramidal, since the lone pair is stereochemically active and occupies an equatorial position together with the carbon atoms of the tellurocycles. If secondary Te?S interactions are considered also, the coordination sphere around tellurium is best described as bicapped Ψ-trigonal-bipyramidal for the complexes with two intramolecular Te?S secondary bonds and monomeric molecular structures, and pentagonal-bipyramidal for the complexes in which neighboring molecules in the crystal lattice are linked through additional weak intermolecular Te?S secondary bonds to form dimeric supramolecular aggregates.     

Synthesis and reactivity of para-substituted benzoylmethyltellurium(II and IV) compounds: observation of intermolecular C-H-O hydrogen bonding in the crystal structure of (p-MeOC6H4COCH2)2TeBr2

Bis(p-substituted benzoylmethyl)tellurium dibromides, (p-YC₆H₄COCH₂)₂TeBr₂, (Y=H (1a), Me (1b), MeO (1c)) can be prepared either by direct insertion of elemental Te across C_Rf-Br bonds (where C_Rf refers to α-carbon of a functionalized organic moiety) or by the oxidative addition of bromine to (p-YC₆H₄COCH₂)₂Te (Y=H (2a), Me (2b), MeO (2c)). Bis(p-substituted benzoylmethyl)tellurium dichlorides, (p-YC₆H₄COCH₂)₂TeCl₂ (Y=H (3a), Me (3b), MeO (3c)), are prepared by the reaction of the bis(p-substituted benzoylmethyl)tellurides 2a-c with SO₂Cl₂, whereas the corresponding diiodides (p-YC₆H₄COCH₂)₂TeI₂ (Y=H (4a), Me (4b), MeO (4c)) can be obtained by the metathetical reaction of 1a-c with KI, or alternatively, by the oxidative addition of iodine to 2a-c. The reaction of 2a-c with allyl bromide affords the diorganotellurium dibromides 1a-c, rather than the expected triorganotelluronium bromides. Compounds 1-4 were characterized by elemental analyses, IR spectroscopy, ¹H, ¹³C and ¹²⁵Te NMR spectroscopy (solution and solid-state) and in case of 1c also by X-ray crystallography. (p-MeOC₆H₄COCH₂)₂TeBr₂ (1c) provides, a rare example, among organotellurium compounds, of a supramolecular architecture, where C-H-O hydrogen bonds appear to be the non-covalent intermolecular associative force that dominates the crystal packing.     

X-ray characterization of Te(S2CNC5H10)2 and TeI2[(C13H10N2S)2] · 4C4H8TeI2; the first Te–C bond cleaved products obtained in the substitution reactions of organo(heterocyclic)tellurium(IV) derivatives

The reaction of organo(heterocyclic)tellurium(IV) derivative: C₈H₈TeI₂(1,3-dihydro-2λ⁴-benzotellurole-2,2-diyl diiodide) with NH₄S₂CNC₅H₁₀ (ammonium piperidine dithiocarbamate) gives C₈H₈Te(S₂CNC₅H₁₀)₂ (1) and Te(S₂CNC₅H₁₀)₂ (2) or C₈H₈TeI(S₂CNC₅H₁₀) (5) according to the reaction conditions. In such type of metathetical reactions, the formation of 2 is unprecedented and it corresponds to the first Te–C cleaved product. The reaction of 2 with CH₃I, yields the oxidative addition product, CH₃TeI(S₂CNC₅H₁₀)₂ (8). The formation of 2 is also supported through Quantum Chemical calculations. Another Te–C bond cleaved product TeI₂[(C₁₃H₁₀N₂S)₂] · 4C₄H₈TeI₂ (9) is obtained in the reaction of C₄H₈TeI₂ (1,1,2,3,4,5-hexahydro-1,1-diiodotellurophene) with NH₄S₂CNHC₆H₅ (ammonium aniline dithiocarbamate). The reaction of 1,1,2,3,4,5,6-heptahydro-1-iodo-1-(morpholine dithiocarbamato) tellurane [C₅H₁₀TeI(S₂CNC₄H₈O)] (10) with 1,10-phenanthroline gives an unusual product C₁₂H₈N₂ · C₄H₁₀INO (11). The structures of the new complexes 2, 8, 9, 10 and 11 have been determined by the X-ray analysis.     

Synthesis, characterization and structural studies of dithiocarbamate derivatives of 2,2,6,6-tetramethyl-1-oxa-4,4-diiodo-4-tellura-2,6-disilacyclohexane,O[Si(CH3)2CH2]2TeI(dtc)

Five new hetero-organotellurium (IV) dithiocarbamates O[Si(CH₃)₂CH₂]₂TeIS₂CN(CH₂CH₂)₂ (1), O[Si(CH₃)₂CH₂]₂TeIS₂CN(CH₂CH)₂ (2), O[Si(CH₃)₂CH₂]₂TeIS₂CN(CH₂CH₂)₂O (3), O[Si(CH₃)₂CH₂]₂-TeIS₂CN(CH₂CH₂)₂S (4) and O[Si(CH₃)₂CH₂]₂TeIS₂CN(CH₂CH₂)₂CH₂ (5) were prepared from the 2,2,6,6-tetramethyl-1-oxa-4,4-diiodo-4-tellura-2,6-disilacyclohexane and the corresponding dithiocarbamate (dtc) sodium salts in ethanol. The compounds were characterized by means of Elemental Analyses, FAB MS, IR, ¹H, ¹³C, ¹²⁵Te NMR spectroscopy. The crystal structures of 1, 3 and 4 were determined. Dithiocarbamate ligands display an anisobidentate chelating coordination mode on interacting with the tellurium center in all compounds. The Te(IV) immediate environment can be described as that of a sawhorse structure in which the lone pair is apparently stereochemically active and occupying an equatorial position in a distorted trigonal bipyramid. The two methylene groups occupy the other equatorial positions with a sulfur atom of the dithiocarbamate group and the iodine atom occupying the axial positions. The solid state structures of 3 and 4 exhibit important intermolecular interaction Te?S(2B). This interaction results in the formation of a dimer, which is better described as a distorted octahedron with an apparently inactive lone pair.     

Imine-functionalized, fluorescent organomercury and -tellurium compounds

Unsymmetrical diorganotellurium(IV) dihalides, Ar′(Ar)TeCl₂ [Ar′ = 2-(R-CHN-C₆H₃Me; R = 1-pyrenyl, 9-anthracenyl and 9-phenanthrenyl; Ar = 4-MeO-C₆H₄, 1-C₁₀H₇, 2,4,6-Me₃-C₆H₂, C₆H₅, 4-Me-C₆H₄] were synthesized from transmetallation reactions of Ar′HgCl and ArTeCl₃. Orthomercuration of the Schiff’s bases (Ar′H) afforded Ar′HgCl. All of these compounds have been characterized with the help of IR, multinuclear (¹H, ¹³C) solution NMR and ESI-HRMS spectrometry. X-ray crystal structures of pyrenyl Ar′HgCl; pyrenyl Ar′(Ar)TeCl₂ (Ar = 4-MeO-C₆H₄); anthranyl Ar′(Ar)TeCl₂ (Ar = 4-MeO-C₆H₄ and 1-C₁₀H₇) and; phenathranyl Ar′(Ar)TeCl₂ (Ar = 1-C₁₀H₇) have been determined. Intramolecular Hg/Te?N interactions are present in these structures. Fluorescence studies of these compounds have also been carried out.