Marek Bouška

Intramolecularly Coordinated Organotin Tellurides: Stable or Unstable?

The step-wise oxidation of an organotin(I) compound with elemental tellurium gave a variety of unprecedented organotin tellurides containing tin atoms in the oxidation states +II and +IV.

Intramolecularly Coordinated Tin(II) Selenide and Triseleneoxostannonic Acid Anhydride

Understanding the nature of chemical bonding remains a central focus of fundamental research, and one of the valuable methods for the increasing of the understanding of intramolecular binding forces is the investigation of compounds containing multiple bonds between heavier Group 14 elements of the type RE ER (where E= group elements Si, Ge, Sn, and Pb). Recent studies of these heavier Group 14 element analogues of alkynes revealed essential structural differences between alkynes, RC CR, and their heavier Group 14 analogues, RE ER (E=Si, Ge, Sn, Pb) and opened debate as to whether the Group 14 analogue compounds exhibit a true triple bond (A), a double bond (B), or a single bond whose geometry is strongly trans-bent (C) (see Scheme 1). The presence of rather bulky substituents such as a variety of substituted aryl and silyl groups afforded the synthesis of RE ER that possess multiple bonds. The presence of a multiple bond was proposed by the UV/Vis absorptions, molecular orbital (MO) calculations, and also by the reactivity studies on these molecules. All these experiments afforded insights into the nature of the E E triple bonds. Scission of the Si Si or Ge Ge triple bond was observed by the addition of an olefin 9, 22–27] and most recently, Power and coworkers nicely outlined the cleavage of the Sn Sn multiple bond in the distannyne [ArSnSnAr] (Ar=C6H3-2,6-(C6H32,6-iPr2)2) by complexation with two molecules of either ethylene or norbornadiene or by cyclic polyolefinic molecules. 29] Moreover, the latest study dealing with the reactivity of [ArSnSnAr] with cyclooctatetraene (cot) showed the powerful reducing character of the tin(I) compound towards neutral cot. Recently, we have shown that the use of intramolecularly coordinating built-in N,C,N-coordinating pincer-type ligands is an alternative concept for the synthesis and stabilization of the reactive distannyne [({2,6-(Me2NCH2)2C6H3}Sn)2] (1). This compound showed, however, Sn Sn single bond character with a central tin atom in the oxidation state + I. We have, therefore, concentrated on the redox-type reaction of compound 1 instead of cycloadditions of the olefins. In the course of a systematic studies on the metal-type redox reactivity of 1 we present here the reaction of 1 with Se as the oxidizing agent and show that the reaction results in the two-step oxidation of the tin(I) atom along with complete cleavage of the Sn Sn bond to give a new organotin(II) selenide [({2,6-(Me2NCH2)2C6H3}Sn)2Se] (2) in the first step of the oxidation (Scheme 2). This compound is unprecedented and there is no report on well-defined selenides of low-valent Group 14 elements. Preparation of organotin(IV) selenide [({2,6-(Me2NCH2)2C6H3}Sn(Se))2Se] (3), the first example of an intramolecularly coordinated triseleneoxostannonic acid anhydride, as the final product of the oxidation of 1 by Se is reported as well (Scheme 2). Compound 3 contains two terminal Sn Se bonds and represents a new [a] M. Bouška, Dr. L. Dost l, Dr. A. Růžička, Dr. R. Jambor Department of General and Inorganic Chemistry Faculty of Chemical Technology University of Pardubice Čs legi 565, 53210, Pardubice (Czech Republic) E-mail : roman.jambor@upce.cz [b] Dr. F. de Proft Eenheid Algemene Chemie (ALGC) Vrije Universiteit Brussel (VUB) Pleinlaan 2, 1050 Brussels, (Belgium) [c] Prof. A. Lyčka Research Institute for Organic Chemistry VUOS a.s. 532 10, Pardubice, (Czech Republic) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.201002641. Scheme 1. Canonical formulas for compounds of the type REER.

Oxidation of intramolecularly coordinated distannyne by S8: from tin(I) to tin(IV) polysulfide via tin(II) sulfide.

The investigation of heavier Group 14 element analogues of alkynes of the type (RE)2 (where E=Si, Ge, Sn, or Pb) is of current interest. These studies showed that the presence of rather bulky substituents such as a variety of substituted aryl and silyl groups allowed the synthesis of RE ER, which possess multiple bonds. The studies dealing with the reactivity of the RE ER multiple bonds showed scission of the Si Si or Ge Ge triple bond by the addition of an olefin, and most recently, Power and coworkers nicely outlined the cleavage of the Sn Sn multiple bond in the distannyne [ArSnSnAr] (Ar=C6H3-2,6-(C6H32,6-iPr2)2) by complexation with two molecules of either ethylene or norbornadiene. Moreover, the latest study dealing with the reactivity of [ArSnSnAr] with cyclooctatetraene (cot) showed the powerful reducing character of the tin(I) compound towards neutral cot. The reactivity studies of [ArSnSnAr] towards N2O also showed the reducing character of the Sn species, yielding the organotin(II) oxide [ArSnOSnAr] as the final product. Recently, the single-bonded dimeric species [{SiACHTUNGTRENNUNG(NtBu)2CPh}2] and [({2,6-(Me2NCH2)2C6H3}Sn)2] (1), as the first example of an Sn N intramolecularly coordinated distannyne containing a built-in N,C,N-pincer-type ligand, were reported as well. The redox reaction of [{Si ACHTUNGTRENNUNG(NtBu)2CPh}2] with N2O showed the reducing character of the Si I species, and led to the production of the well-defined [R4Si4O6] compound (R= (NtBu)2CPh) with a double-decker structure. [8]

Mixed Organotin(IV) Chalcogenides: From Molecules to Sn‐S‐Se Semiconducting Thin Films Deposited by Spin‐Coating

Put the right spin on it: Mixed monomeric organotin(IV) chalcogenides of the general formula L(2)Sn(2)EX(2) containing two terminal Sn-X (X = Se, Te) bonds were prepared and were tested as potential single-source precursors for the deposition of semiconducting thin films. Spin-coating deposition of [{2,6-(Me(2)NCH(2))(2)C(6)H(3)}SnSe](2)(μ-S), as the useful single-source precursor, provided amorphous Sn-S-Se semiconducting thin films.

Pulsed laser deposited GeTe-rich GeTe-Sb2Te3 thin films.

Pulsed laser deposition technique was used for the fabrication of Ge-Te rich GeTe-Sb2Te3 (Ge6Sb2Te9, Ge8Sb2Te11, Ge10Sb2Te13, and Ge12Sb2Te15) amorphous thin films. To evaluate the influence of GeTe content in the deposited films on physico-chemical properties of the GST materials, scanning electron microscopy with energy-dispersive X-ray analysis, X-ray diffraction and reflectometry, atomic force microscopy, Raman scattering spectroscopy, optical reflectivity, and sheet resistance temperature dependences as well as variable angle spectroscopic ellipsometry measurements were used to characterize as-deposited (amorphous) and annealed (crystalline) layers. Upon crystallization, optical functions and electrical resistance of the films change drastically, leading to large optical and electrical contrast between amorphous and crystalline phases. Large changes of optical/electrical properties are accompanied by the variations of thickness, density, and roughness of the films due to crystallization. Reflectivity contrast as high as ~0.21 at 405 nm was calculated for Ge8Sb2Te11, Ge10Sb2Te13, and Ge12Sb2Te15 layers.

Intramolecularly coordinated gallium sulfides: Suitable single source precursors for GaS thin films

Our studies have been focused on the synthesis of N→Ga coordinated organogallium sulfides [L1 Ga(μ-S)]3 (1) and [L2 Ga(μ-S)]2 (2) containing either N,C,N- or C,N-chelating ligands L1 or L2 (L1 is {2,6-(Me2 NCH2 )2 C6 H3 }- and L2 is {2-(Et2 NCH2 )-4,6-tBu2 -C6 H2 }- ). As the result of the different ligands, compounds 1 and 2 differ mutually in their structure. To change the Ga/S ratio, unusually N→Ga coordinated organogallium tetrasulfide L1 Ga(κ2 -S4 ) (3) was prepared and the unprecedented complex [{2-[CH{(CH2 )3 CH3 }(μ-OH)]-6-CH2 NMe2 }C6 H3 ]GaS (4) was also isolated as the minor by-product of the reaction. Compounds 1-3 were further studied as potential single-source precursors for amorphous GaS thin film deposition by spin-coating.

N-Coordinated Tin(II) Trifluoromethanesulfonates and Their Reactions with Transition Metal Carbonyls

The syntheses of the compounds [L(1)SnCl][M(CO)5(SnCl3)] (3, M = W; 4, M = Cr), [L(1)SnCl]OTf (5), [L(1)SnCl][W(CO)5(SnCl2OTf)] (6), [L(1)SnOTf][OTf] (7), and [L(2)Sn(OTf)2] (8) with L(1) = {2,6-[(CH3)C═N(C6H3-2,6-(i)Pr2)2]C5H3N} (DIMPY) and L(2) = {2-[(CH3)C═N(C6H3-2,6-(i)Pr2)]-6-(CH3O)}C5H3N) is reported. The compounds were characterized by elemental analyses, (1)H, (13)C, (19)F, and (119)Sn NMR spectroscopy, electrospray ionization mass spectrometry, and single-crystal X-ray diffraction analyses (3·1.5C7H8, 5·CH2Cl2, 7·C7H8, 8). For compounds 7 and 8, the experimental work is accompanied by density functional theory calculations.

Laser Desorption Ionization of As2Ch3 (Ch = S, Se, and Te) Chalcogenides Using Quadrupole Ion Trap Time-of-Flight Mass Spectrometry: A Comparative Study

AbstractLaser desorption ionization using time-of-flight mass spectrometer afforded with quadrupole ion trap was used to study As2Ch3 (Ch = S, Se, and Te) bulk chalcogenide materials. The main goal of the study is the identification of species present in the plasma originating from the interaction of laser pulses with solid state material. The generated clusters in both positive and negative ion mode are identified as 10 unary (Sp+/– and Asm+/–) and 34 binary (AsmSp+/–) species for As2S3 glass, 2 unary (Seq+/–) and 26 binary (AsmSeq+/–) species for As2Se3 glass, 7 unary (Ter+/–) and 23 binary (AsmTer+/–) species for As2Te3 material. The fragmentation of chalcogenide materials was diminished using some polymers and in this way 45 new, higher mass clusters have been detected. This novel approach opens a new possibility for laser desorption ionization mass spectrometry analysis of chalcogenides as well as other materials. Graphical abstractᅟ

Synthesis, Structure and Application of Intramolecularly-Coordinated Gallium Chalcogenides: Suitable Single-Source precursors for Ga x Se y Materials

Studies have been focused on the synthesis of N→Ga-coordinated organogallium selenides and tellurides [L1 Ga(μ-Se)]2 (1), [L2 Ga(μ-Se)]2 (2) and [L1 Ga(μ-Te)]2 (3), respectively, containing either N,C,N- or C,N-chelating ligands L1, 2 (L1 is {2,6-(Me2 NCH2 )2 C6 H3 }- and L2 is {2-(Et2 NCH2 )-4,6-tBu2 -C6 H2 }- ) having Ga/E (E=Se or Te) atoms in 1/1 ratio. To change the Ga/E ratio, an unusual N→Ga-coordinated organogallium tetraselenide L1 Ga(κ2 -Se4 ) (4) was prepared. An unprecedented complex (L1 Ga)2 (μ-Te2 )(μ-Te) (5), as the result of the non-stability of 3, was also isolated. Compound 2 is a suitable single-source precursor for the preparation of amorphous GaSe thin films by the spin coating. Moreover, simple heating of an octadecylamine solution of 2 provided, after work up, monoclinic Ga2 Se3 crystals with different crystallinity according to conditions used. Therefore, compound 2 may be also used as a source of Ga2 Se3 in the low-temperature doping process of Bi2 Se3 .

Amorphous Ge-As-Te thin films prepared by pulsed laser deposition: A photostability study

Pulsed laser deposition was used for the fabrication of amorphous thin films from Ge-As-Te system with the aim to study their intrinsic photostability. Photostability of prepared layers was studied using spectroscopic ellipsometry within as-deposited as well as relaxed layers. For irradiation, laser sources operating at three energies (1.17, 0.92 and 0.8 eV) in band gap region of the studied materials were employed. The lowest values of photorefraction (refractive index changes) accompanied with lowest changes of band gap values present Ge20As20Te60 thin films, which are therefore considered as the layers with highest photostability, especially in relaxed state.