Thermolytic Behavior Research Articles

Surface Thermolytic Behavior of Nickel Amidinate and Its Implication on the Atomic Layer Deposition of Nickel Compounds

Atomic layer deposition (ALD) is a highly important technology to fabricate nickel and nickel compound thin films. The quality of the ALD films relies much on the surface chemistry reactions involved in the ALD process. Aiming to achieve high-quality ALD films, a careful surface chemistry study is carried out in this work to investigate the surface thermolysis behavior of an amidinate-type nickel precursor, bis(N,N′-di-tert-butylacetamidinato)nickel(II) (Ni(amd)2). Using the in situ technique of X-ray photoelectron spectroscopy, this work reveals a number of implications which are important for the engineering of the ALD processes. The Ni(amd)2 precursor is shown to be reactive to the SiOx surface even at room temperature, which suggests a good suitability for low-temperature ALD. The surface amidinate moiety is found to decompose at 250 °C, which suggests the limitation of Ni(amd)2 for high-temperature ALD. On the other hand, the byproduct of the surface reaction, amidine, can be adsorbed on the surface ...

Perfluorinated tert‐Butoxides of Tin(II): The Dimeric Alkoxide and Its Monomeric Ate Complex

Surprisingly little is known about fluorinated tin(II) alkoxides. Here the synthesis and characterization of Sn(ORF)2 [ORF = OC(CF3)3] and the crystal structures of its adducts with phenanthroline and dppe are reported. In addition, its ate complex [Sn(ORF)3]– was synthesized with lithium or sodium as cation and as acetonitrile adduct. The thermolytic behavior of both, the alkoxide and the lithium stannate(II), was investigated together with first electrochemical measurements of Li[Sn(ORF)3].

Synthesis of [Ru3(CO)9(μ-dppf){P(C4H3E)3}] (E = O, S) and thermally induced cyclometalation to form [(μ-H)Ru3(CO)7(μ-dppf){μ3-(C4H3E)2P(C4H2E)}] (dppf = 1,1′-bis(diphenylphosphino)ferrocene)

The new clusters [Ru3(CO)9(μ-dppf){P(C4H3E)3}] (1, E = O; 2, E = S) have been prepared from the Me3NO-induced decarbonylation of [Ru3(CO)10(μ-dppf)] in the presence of PFu3 (E = O) and PTh3 (E = S), respectively. Upon thermolysis in benzene, the major products are the cyclometalated clusters [(μ-H)Ru3(CO)7(μ-dppf){μ3-(C4H3E)2P(C4H2E)}] (3, E = O; 4, E = S). This thermolytic behavior is in marked contrast to that previously noted for the analogous bis(diphenylphosphino)methane (dppm) complexes [Ru3(CO)9(μ-dppm){P(C4H3E)3}], in which both carbon–hydrogen and carbon–phosphorus bond activation yields furyne- and thiophyne-capped clusters. The crystal structures of 1, 3 and 4 are presented and reveal that phosphine migration has occurred during the transformation of 1,2 into 3,4, respectively. The possible relation of the observed reactivity to the relative flexibilities of the diphosphine ligands is discussed. Density functional calculations have been performed on the model cluster [Ru3(CO)9(μ-Me4-dppf){P(C4H3O)3]}], and these data are discussed relative to the ground-state energy differences extant between the different isomeric forms of this cluster. The dynamic NMR behavior displayed by the metalated thienyl ring in cluster 4 has also been investigated by computational methods, and the free energy of activation for the “windshield wiper” motion of the activated thienyl moiety determined.

統計的手法を用いたバイオマスの熱分解挙動モデルの検討

統計的手法を用いたバイオマスの熱分解挙動モデルの検討

Synthesis and thermolytic behavior of tin(iv) formates: in search of recyclable metal–hydride systems

The synthesis and characterization of the series of organotin formates together with their thermolytic behavior are described. The diformate Bu(n)(2)Sn{OC(O)H}(2) (1) was synthesized by the reaction of Bu(n)(2)SnH(2) with formic acid. The triorganotin monoformate compounds R(3)SnOC(O)H (R = Cy (cyclohexyl)) 3, Mes, (mesityl, 2,4,6-trimethylphenyl) 4, and Dmp (2,6-dimethylphenyl 5) were obtained by the reaction of R(3)SnOH with formic acid. Their X-ray crystal structures along with that of the previously reported formate (PhCH(2))(3)SnOC(O)H (2) were determined. The diformate 1 exhibits an extended two-dimensional polymeric structure in which six-coordinate tin centers are linked by formate bridges. The tribenzyltin formate (2) possesses a chain structure in which the five-coordinate Sn(CH(2)Ph)(3) units are bridged by formate ions. The cyclohexyl derivative 3 was observed to have a similar structure. In contrast, the Mes and Dmp derivatives 4 and 5 support monomeric structures in which the four-coordinate tin atom is bound to an oxygen of the formate ligand. Heating the compounds in various high boiling solvents produced no decomposition up to 120 °C in the case of 1 and refluxing a solution of 2 or 3 in mesitylene or diglyme left the starting material mostly unchanged, although 3 decomposed to an insoluble orange solid in refluxing decalin. In contrast, the heating of 4 and 5 in refluxing mesitylene led to elimination of CO to give the tin hydroxides. The results are in contrast to the known thermolytic behavior of R(3)SnOC(O)H (R = Pr(n) or Bu(n)) complexes, which eliminate CO(2) to generate R(3)SnH. Compounds 3-5 are rare examples of structurally characterized tin formates.

Reactions of sterically congested 1,5-hexadienes: Ab initio and DFT calculations on the competition between cope rearrangements and disrotatory cyclobutene ring-opening reactions of bridged syn-tricyclo[4.2.0.0(2,5)]octa-3,7-dienes.

The thermolytic behavior of four syn-tricyclo[4.2.0.0(2,5)]octa-3,7-dienes, each spanned by four propano bridges (13, 14, 21, and 26), has been investigated by means of calculations at the UB3LYP/ 6-31G* and CASPT2/6-31G levels. These calculations predict that 13 should undergo a degenerate Cope rearrangement (E(A) = 19.6 kcal/mol), whereas the other three C(20)H(24) isomers should prefer a necessarily disrotatory cyclobutene ring-opening reaction. In the case of 14, the ring-opening reaction (E(A) = 27.2 kcal/mol) is concerted and leads directly to 15, a 4-fold bridged cyclooctatetraene. In the ring opening of 21, the 1,6-bridge in the 4-fold bridged bicyclo[4.2.0]octa-2,4,7-triene 31 prevents formation of the corresponding cyclooctatetraene. In the ring opening of 26, the 4-fold bridged bicyclo[4.2.0]octa-2,4,7-triene derivative 36 is predicted to form the corresponding bridged cyclooctatetraene 38, which should undergo bond shift. The results of these calculations are found to be in very good agreement with the results of experiments on these hydrocarbons.

Synthesis, characterization and thermolysis of phosphinite–borane adducts: investigation of an unusual thermally-induced phenol elimination reaction

The synthesis, characterization and thermolytic behavior of a new class of phosphinite–borane adducts containing the bulky 2,4,6-t-Bu3C6H2O (Mes*O) group is reported, including the description of the first example of a primary phosphinite–borane adduct isolable at room temperature (Mes*O)PH2·BH31. Adduct 1 and the phenylated derivative (Mes*O)PhPH·BH33 formed highly cross-linked solids, 7 and 8, when heated to 100 and 140 °C, respectively. Characterization of these solids by solid state and solution NMR spectroscopy suggest that both dehydrocoupling (H2 elimination) and Mes*OH elimination occur simultaneously to give the complex products [(Mes*O)xRPHy–BH(2x + 2y + z)]n (R = H or Ph, x + y + z = 1). The tertiary adduct (Mes*O)Ph2P·BH35 and the phosphite–borane (PhO)3P·BH36 were found to decompose at high temperatures via P–B bond cleavage without formation of the corresponding phenol. These results suggest that the thermally-induced formation of Mes*OH from 1 and 3 occurs via α-elimination from a phosphorus center. Adducts 1, 3, 5 and 6 were also structurally characterized by single-crystal X-ray diffraction.

Thermolytic Behavior of Crude Oil- and Natural Asphalt-derived Asphaltenes in the Presence of Several Aromatic Solvents.

Thermolytic behavior of asphaltene fractions derived from both vacuum residue of Arabian crude oil and Indonesian natural asphalt was investigated. At first, the asphaltenes were analyzed by 1H- and 13C-NMR spectroscopy to obtain structural information. Structural differences between the two asphaltenes were found in the amount of naphthenic carbon and in the size of polycyclic aromatic units. The asphaltene obtained from Indonesian natural asphalt contains much larger amount of naphthenic carbon but smaller size of polycyclic aromatic units compared those from Arabian crude. Thermal treatments of the asphaltene were conducted in a glass tube at 420°C for 5min in the presence or in the absence of aromatic solvents. The molecular weight distribution of the samples and the products was evaluated by using a gel permeation chromatography. Among the solvents used, partially hydrogenated aromatic compounds such as 9, 10-dihydroanthracene (DHA) showed a slight effect on thermolysis of asphaltene, while polycyclic aromatic compounds such as anthracene (Ant) or acridine (Acr) were more effective. These results could be explained by referring to the radical acceptability of these aromatic solvents.

Conductive F-doped Tin Dioxide Sol−Gel Materials from Fluorinated β-Diketonate Tin(IV) Complexes. Characterization and Thermolytic Behavior

Hydrolysis and condensation of (CH3COCHCOCH3)2SnF(Otert-Am) and (CF3COCHCOCH3)2Sn(Otert-Am)2 gave soluble stannic oxo-oligomers or -polymers including fluorine and β-diketonate groups. Under thermal treatment in air at 550 °C, they yielded nanocrystalline fluorine-doped tin dioxide powders. The amount of remaining ligands in the xerosols depends on the hydrolysis ratio and on the nature of the solvent used, dimethylformamide (DMF) favoring ligand removal. The thermolytic reactions have been investigated by thermogravimetry coupled to mass spectrometry: (1) the β-diketonate ligands pyrolyze in two stages, at 200 and 320 °C, involving two different processes; (2) elimination of polar solvents of high boiling point, such as DMF, occurs up to 300 °C; (3) fluorine is lost as fluorhydric acid from 230 °C. The best strategy to prepare F-doped SnO2 materials by the sol−gel route is thus to start from precursors including Sn−F bonds and to use a polar aprotic solvent of low boiling point such as acetonitrile. It l...

Synthesis and Thermolytic Behavior of Mixed-Valence Homo- and Heterometallic Group 14 Alkoxides

The mixed-valence molecule Sn{sup II}Sn{sup IV} (OPr){sub 6} is conveniently synthesized and is shown to exchange bridging and terminal alkoxides in solution in its Sn({micro}-OPr){sub 3}Sn(OPr){sub 3} structure. Pb{sub 3}SnO(POr){sub 8} is synthesized and shown to undergo an intramolecular fluxional process in solution. Both molecules are sufficiently volatile for CVD study, and comparison of CVD behaviors of these and of M(OPr){sub 2} (M = Sn, Pb), Sn(POr){sub 4}, SnZr(OPr){sub 6}, and Pb{sub 3}-ZrO(OPr){sub 8} shows the reducing capacity of the isopropoxide moiety dominates the thermolytic behavior of all these species, giving metallic Sn or Pb in all cases. Only Zr, when it is present, forms ZrO{sub 2}. The oxide in Pb{sub 3}SnO(POr){sub 8}yields PbO (and 2 Pb{sup 0} and 1 Sn{sup 0}), in contrast to the relative electropositivity of Sn and Pb, a fact attributed to kinetic control of CVD behavior.

Thermolytic behavior of polydienyllithium and polystyryllithium

UV absorption spectra of thermolyzed polybutadienyl- and polyisoprenyl-lithium reveal a chromophore group previously not recognized for such systems; its absorption band at 271 nm has been assigned to a structure with three conjugated double bonds. A two-step mechanism for the formation of this trienic structure is proposed: an intermolecular metallation of associated living ends is followed by lithium hydride (LiH) elimination. Along thermolysis the presence of a dienic structure was also recognized, the latter arising from intramolecular elimination of LiH. The trienyllithium structure is also considered to be an effective species for the observed molecular weight distribution (MWD) variations. The observed different extent of high molecular weight (HMW) for polyisoprenyl- and polybutadienyl-lithium is explained on the basis of a different stability of the intermediates present along the proposed reaction mechanism. The thermolytic behavior of polystyryllithium does not provide any significant change in MWD: the disappearance of the living chain ends, UV detected, is due to an intramolecular LiH elimination which obeys first-order kinetics. The influence of temperature and of the tetrahydrofuran (THF) level on kinetic rate constants was investigated. © 1996 John Wiley & Sons, Inc.

ChemInform Abstract: Thermochromic Furofurans. Part 2. Synthesis and Thermolytic Behavior of Spiroquinole Ethers with Naphthalene Nucleus.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Thermochrome Furofurane, II. Synthese und Thermolyseverhalten substituierter Spirochinolether der Naphthalinreihe

Thermochromic Furofuranes, II. — Synthesis and Thermolytic Behavior of Spiroquinole Ethers with Naphthalene NucleusTo obtain further insight into the new photochromic system 2/3, various 3,4‐disubstituted spiroquinole ethers 7 have been synthesized by oxidation of 2‐alkyl‐4‐methoxy‐1‐naphtholes 5 via the corresponding quinone methides 6. Unlike 7a, the ethers 7b–d did not yield dimeric quinone methides or furofuranes (type 2/3) on heating, but decomposed by retro‐diene reaction yielding monomeric methides 6. The sterically hindered methides 6e, 6f are stable yellow compounds; 6c rearranged forming 12 which led to the naphthopyranes 11a/11b on further reaction with 6c.

Characterization of thermolysis products of cuticular wax compounds of green tobacco leaf

A study was undertaken to determine the pyrolysis products of leaf surface constituents of tobacco that may contribute to the flavor and aroma of smoke. Compounds previously identified in cuticular waxes of green tobacco (diterpenes, aliphatic alcohols, wax esters, hydrocarbons) were subjected to semimicro pyrolyses within a range of temperatures (200–800°C) that are encountered during smoking of tobacco products. Recovered products were characterized by gas chromatography/mass spectrometry. During thermolysis, the aliphatic hydrocarbons were found to undergo thermal desorption. The C 22 alcohol, docosanol, exhibited thermolytic behavior analogous to that of the paraffinic hydrocarbons, mainly distilling and producing only minor amounts of the corresponding 1-alkene. The duvane diterpenes, the α- and β-duvatrienediols, yielded four major products, with mass spectrometric characteristics of C 20 monols or C 20-seco cembranoids. The labdane diterpene, cis-abienol, thermally isomerized to the trans-neo-abienol isomer. The thermal degradation of wax esters increased with chain length, producing the corresponding alkene, alcohol, and acid products.

ChemInform Abstract: Phosphorus‐Nitrogen Triple‐Bonded Species

Abstract Evidence for the transient formation of new phosphorus-nitrogen triple bonded species are given. Rules concerning the photolytic and thermolytic behavior of azides are reported.

PHOSPHORUS-NITROGEN TRIPLE-BONDED SPECIES

Abstract Evidence for the transient formation of new phosphorus-nitrogen triple bonded species are given. Rules concerning the photolytic and thermolytic behavior of azides are reported.

Thermolytic behavior of some 1-oxa-substituted 1-(trimethylsilyl)cyclopropanes

Thermolytic behavior of some 1-oxa-substituted 1-(trimethylsilyl)cyclopropanes

The synthesis of bridged biphenyl and naphthyl compounds by the photolytic and thermal extrusion of SO2

The photolytic and flash vacuum thermolytic behavior of several SO2-containing cyclic compounds was studied. The expulsion of SO2 by flash vacuum thermolysis afforded the corresponding bridged compounds in high yield.

Selectivity in retro-ene vs. cyclopentene rearrangements of a cis-methylvinylcyclopropane

The thermolytic behavior of 6β-ethenyl-1β-methyl-bicyclo [3.1.0] hexane-2-one was examined at a wide range of temperatures and with diverse catalytic surfaces. Conditions are reported to effect selectivity between the retro-ene and the cyclopentene modes of rearrangement. The synthetic scope of these transformations is indicated.