Steinar Husebye

N-{2-(4-Methoxyphenyltelluro)ethyl}morpholine (L1) and bis{2-(N-morpholino)ethyl}telluride (L2): synthesis and complexation with palladium(II) and mercury(II). Crystal structures of trans-[PdCl2(L1)2] and trans-[PdCl2(L2)2]

Abstract The reactions of 4-(2-chloroethyl)morpholine hydrochloride with ArTe− and Te2−, generated in situ (under N2 atmosphere) have resulted in N-{2-(4-methoxyphenyltelluro)ethyl}morpholine (L1) and bis{2-(N-morpholino)ethyl}telluride (L2), respectively, which are first tellurated derivatives of morpholine. 1H- and 13C{1H}-NMR spectra of L1 are as expected but HETCOR experiments are used to assign the overlapping signals of CH2Te and CH2N in 1H-NMR spectrum of L2. The complexes of stoichiometries [PdCl2(L1/L2)2] (1/3) and [HgBr2(L1/L2)]2 (2/4) are synthesized. The NMR (1H and 13C{1H}) spectra of all the four complexes have CH2Te and ArCTe signals deshielded with respect to those of free L1/L2, indicating that the two ligands coordinate through Te only. The trans Pd-complexes 1 and 3 are characterized structurally and their PdTe bond lengths (average) are 2.596 and 2.600 A, respectively. The Pd-Cl bonds in 1 are marginally shorter (average 2.312 A) in comparison to those of 3 (average 2.325 A). The geometry of palladium is square planar. The TeC(aryl) is shorter than TeC(alkyl). The dimeric mercury complexes 2 and 4 appear to be formed through the formation two bromo bridges between Hg atoms.

Reaction of large-bite ligands with various tellurium compounds: Synthesis and structural characterization of [Te2(μ-Cl)2{(SPPh2)2N}2], [(4-MeOC6H4TeCl3)2{μ-Ph2P(S)CH2CH2P(S)Ph2}] and [Te2(μ-Ph2PS2)2] representing novel types of tellurium complexes

Abstract The three title compounds have been synthesized and their structures determined by X-ray crystallography. [Te2(μ-Cl)2{(SPPh2)2N}2], 1, is a dinuclear square planar Te(II) complex where each Te atom is coordinated to the two sulfur atoms of the bidentate dithiolate ligand and to the two bridging chloride ligands. The Te–S bond lengths are 2.4980(8) and 2.5054(8) A, while the Te–Cl bond lengths are 2.9065(9) and 2.9230(9) A. In [(4-MeOC6H4TeCl3)2{μ-Ph2P(S)CH2CH2P(S)Ph2}], 2, the dithio ligand is neutral and adds a molecule of [4-MeOC6H4TeCl3] at each sulfur atom, thus bridging the two Te(IV) atoms. The coordination of both tellurium atoms is ψ-octahedral with the anisyl group and a lone pair of electrons in axial positions. The Te–S bonds, 2.7747(6) and 2.8198(5) A, are surprisingly weak while the Te–Cl bonds lie in the range 2.4247(5) to 2.5343(6) A, those trans to Te–S being shortest. [Te2(μ-Ph2PS2)2], 3, is a binuclear Te(I) complex, mainly held together by a Te–Te bond of 2.7298(5) A. Both anisobidentate diphenyldithiophosphinate ligands bridge the two tellurium atoms. The resulting coordination around each tellurium is best described as T-shaped with the Te–Te bond along the stem. In the asymmetric near linear S–Te–S system, the short Te–S bonds are 2.487(2) and 2.495(2) A while the long bonds are 2.947(2) and 3.033(2) A, respectively. The strongly different trans influences of the dithio ligands of 1 and 2 are discussed and it is suggested that they are dependent upon the basicity of the sulfur atoms.

SYNTHESIS, NMR STUDIES AND CRYSTAL STRUCTURES OF 1,3-DIHYDRO-2δ4-BENZOTELLUROLE-2, 2-DIYL DIACETATE, C8H8Te(OAc)2 AND 1,3-DIHYDRO-2δ4-BENZOTELLUROLE-2,2-DIYL DIETHYLDITHIOCARBAMATE DIETHYLDITHIO-PHOSPHATE, C8H8Te(Et2NCS2)[(EtO)2PS2]

Abstract The crystal and molecular structures of C8H8Te(OAc)2, 1, and C8H8Te(Et2NCS2)[(EtO)2PS2], 2, have been determined. The crystals of 1 are monoclinic with a = 10.632(1), b = 9.200(1), c = 13.589(1) A, β = 101.330(6)°, Z = 4 and space group P21/a; the crystals of 2 are orthorhombic with a = 6.653(1), b = 9.876(2), c = 36.347(6) A, Z = 4 and space group P212121. In both compounds, the lone pair of electrons of tellurium is stereochemically active. In 1, tellurium is coordinated by the benzylic carbon atoms and by the four oxygens of the two anisobidentate acetate ligands. In addition, the molecules are joined into chains by weak intermolecular Te…O bonds. This results in seven-coordination for the tellurium atom. 2 consists of monomeric molecules where tellurium is bonded to the two benzylic carbons and to the four sulfur atoms of the two anisobidentate dithio ligands. Here, tellurium is six-coordinate. The structures may be described as distorted pseudo dodecahedral (1) and pseudo pentagonal bipyrami...

Synthesis and Structural Characterization of [Te{(SePPh2)2N}2]and 4-MeOPhTe{(SPPh2)2N}2.

Reaction of K[(SePPh2)2N] with [Te(tu)4]Cl2 (tu = thiourea) in methanol gave [Te{(SePPh2)2N}2], (1), while reaction of K[(SPPh2)2N] with 4-MeOPhTeCl3 in methanol gave [4-MeOPhTe-{(SPPh2)2N}]2, (2). The crystals of 1 are triclinic and contain centrosymmetric molecules. The ligands are bidentate and form a true square planar Te(II) complex with TeSe4 coordination. For 2, the crystals are also triclinic, and the dimeric molecules are centrosymmetric. Each dithiolate ligand bridges the two Te(II) atoms; the result is a T-shaped coordination around each tellurium atom. A tendency to weak TeTe bonding across the ring-formed dimer roughly in the direction of the missing fourth ligand in a potential square planar tellurium coordination sphere is also found [TeTe = 3.761 (1) A]. In 1, the Te–Se bonds have an average length of 2.797 A. The Te–S bonds in 2 are quite asymmetric with Te(1)–S(1) = 2.551 (3) A and Te(1)–S(2a) = 2.873 (3) A, while Te(1)–C(1) = 2.10 (1) A.

The reaction of trifluoromethanesulphonic anhydride with carbonyl compounds

Abstract Amides and ureas react with trifluoromethanesulphonic anhydride to give a new type of resonance stabilized dicarbonium salts, R1R2 C + -O- C + R1R2 · 2CF3SO3−.

N-Methylbenzothiazole-2(3H)-selone, C8H7NSSe

The crystal structure of N-methyl-1,3-benzothiazole-2(3H)-selone (mbts) has been studied in order to estimate the changes in the molecular geometry of the mbts ligand upon coordination. Hypervalent complexes of mbts with Te II and I I have been studied by us previously. A significant elongation of the Se=C bond [from 1.817 (7) in mbts to 1.85-1.88 A in the complexes] was found, but there were no significant changes in the other geometric parameters of the ligand. The only other bond-length decrease of note was for SeC-NMe [from 1.35 (1) in mbts to 1.32-1.34 A in the complexes]. Thus, only the amino group takes part in electron redistribution upon coordination.

RECENT DEVELOPMENTS ON THE STRUCTURAL CHEMISTRY OF COMPLEXES OF SELENIUM AND TELLURIUM WITH SULFUR-AND SELENIUM CONTAINING LIGANDS

Abstract The stereochemistry of selenium and tellurium and the role of lone electron pairs will be discussed on the basis of recent X-ray diffraction studies appearing in the literature. Some of the studies represent new types of structures.

The first metal complexes of 1,4-oxatellurane: synthesis and crystal structure of its platinum(II) complex

The palladium(II) and platinum(II) complexes of 1,4-oxatellurane (L), having the composition [MCl2L2], are synthesized and characterized spectroscopically and structurally (Pt complex only; Pt–Cl 2.3169(9) Å; Pt–Te 2.5945(3) Å) for the first time.

Study on Ferrocenes, Part 7. E-2-Ferrocenemethylene-1-benzocyclanones. Synthesis, stereostructure, NMR, IR X-ray, and Mossbauer spectroscopic investigation

Abstract A series of E-2-ferrocenemethylene-1-benzocyclanones (3a–e) were synthesized by base-catalysed condensation of ferrocenecarboxaldehyde (2) with benzocyclanones 1a–e. The stereostructure (configuration and conformation) and the electronic properties (conjugation of the enone moiety with the aromatic rings) of the compounds were studied by IR, 1H and 13C NMR and Mossbauer spectroscopy. The structure of E-2-ferrocenemethylene-1-benzosuberone (3c) was also investigated by X-ray spectroscopy.

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

Since the authors 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