Stereochemical activity of lone pairs of electrons and supramolecular aggregation patterns based on secondary interactions involving tellurium in its 1,1-dithiolate structures

The 3 centre-4 electrons (3c-4e) and the donor/acceptor or charge-transfer models for the description of the chemical bond in linear three-body systems, such as I3– and related electron-rich (22 shell electrons) systems, are comparatively discussed on the grounds of structural data from a search of the Cambridge Structural Database (CSD). Both models account for a total bond order of 1 in these systems, and while the former fits better symmetric systems, the latter describes better strongly asymmetric situations. The 3c-4e MO scheme shows that any linear system formed by three aligned closed-shell species (24 shell electrons overall) has reason to exist provided that two electrons are removed from it to afford a 22 shell electrons three-body system: all combinations of three closed-shell halides and/or chalcogenides are considered here. A survey of the literature shows that most of these three-body systems exist. With some exceptions, their structural features vary continuously from the symmetric situation showing two equal bonds to very asymmetric situations in which one bond approaches to the value corresponding to a single bond and the second one to the sum of the van der Waals radii of the involved atoms. This indicates that the potential energy surface of these three-body systems is fairly flat, and that the chemical surrounding of the chalcogen/halogen atoms can play an important role in freezing different structural situations; this is well documented for the I3– anion. The existence of correlations between the two bond distances and more importantly the linearity observed for all these systems, independently on the degree of their asymmetry, support the state of hypervalency of the central atom.

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The nature of the chemical bond in linear three-body systems: from i3- to mixed chalcogen/halogen and trichalcogen moieties.

Synthesis, characterization and crystal structure of 1,3-dihydro-2λ4-benzotellurole-2,2-diyl bis(N-piperidine-dithiocarbamate), [1,2-C6H4(CH2)2Te(S2CNC5H10)2] (1), 1,3 dihydro-2λ4-benzotellurole-2-iodo-2-yl-diethyldithiophosphinate, [1,2-C6H4(CH2)2TeI(S2PEt2)] (2) and 1,3-dihydro-2λ4-benzotellurole-2-iodo-2-yl dimethyldithiophosphinate, [1,2-C6H4(CH2)2TeI(S2PMe2)] (3)

[NMe4][RfTe(SC(S)NR2)2] derivatives are selectively formed by the oxidation of [NMe4]TeRf (Rf = CF3, C2F5) with [R2NC(S)S]2 (NR2 = NEt2, NBz2, N(CH2)4) in almost quantitative yields. An alternative route to obtain the dithiocarbamato complex anions offer reactions of Te[SC(S)NR2]2 (NR2 = NEt2, NBz2) with equimolar amounts of Me3SiRf and [NMe4]F. Some of the derivatives were recrystallized with bulky cations in order to determine the crystal structures. Structural elucidation by diffraction methods exhibit the structural feature of a distorted pentagonal planar environment (resembling “butterflies”) around the tellurium centres. The carbamato tellurates can be transferred easily into the neutral derivatives, RfTeSC(S)NR2, upon treatment with Ag[BF4]. In solution they equilibrate with Te2(Rf)2 and [R2NC(S)S]2 and finally are transformed into Te(Rf)2, Te[SC(S)NR2]2, and Te[SC(S)NR2]4, respectively. All compounds are fully characterized by NMR spectroscopic methods (1H, 13C, 19F, 125Te). Additionally, synthesis and characterization of the hitherto unknown derivative [NMe4]TeC2F5 are described.

Perfluoroalkyl(dithiocarbamato) tellurium(II) compounds.

Since the author's last surveys of this field in 1983 and 1987,1,2 there has been considerable developments in the structural chemistry of tellurium. A comprehensive review covers the field through most of 1993.3

Recent Developments in the Structural Chemistry of Tellurium with Sulfur and Selenium Containing Ligands

A novel mixed ligand Te(IV) complex comprising three halides and a dithiocarbamate; synthesis and crystal structure of triiododiethyldithiocarbamatotellurium(IV), Te{(C2H5)2NCS2}I3

[Te(C 7 H 14 NS 2 ) 2 ] cristallise dans Pbca avec a=12,411, b=13,679, c=25,579 A, Z=8; affinement jusqu'a R=0,036. Tous les coordinats dithiocarbamates sont lies asymetriquement a l'atome central Te. Autour de Te, il y a une tendance vers la coordination cinq avec un atome S a partir de la molecule situee a la peripherie, realisant ainsi un court contact Te...S

http://journals.iucr.org/c/issues/1990/11/00/as0323/as0323.pdf

Structure of bis(diisopropyldithiocarbamato)tellurium(II)

[Te(C 7 H 14 NS 2 ) 4 ] cristallise dans P2 1 2 1 2 1 avec a=13,946, b=14,833, c=20,213 A, Z=4; affinement jusqu'a R=0,037. L'atome Te central est coordonne 8 fois ainsi les atomes S forment un arrangement dodecaedrique legerement tordu autour du metal. La paire libre des electrons sur Te(IV) est stereochimiquement inerte. On observe des contacts courts S...S entre les coordinats

http://journals.iucr.org/c/issues/1990/11/00/li0028/li0028.pdf

K. Yvon

Papers

A novel mixed ligand Te(IV) complex comprising three halides and a dithiocarbamate; synthesis and crystal structure of triiododiethyldithiocarbamatotellurium(IV), Te{(C2H5)2NCS2}I3

Structure of bis(diisopropyldithiocarbamato)tellurium(II)

Structure of tetrakis(diisopropyldithiocarbamato)tellurium(IV)