京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21268号 / 工博第4496号 / 新制||工||1699(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 小澤 文幸, 教授 大江 浩一, 教授 中村 正治 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

N-Heterocyclic carbenes (NHCs) have attracted growing interest not only as successful ancillary ligands in a wide variety of transition-metal-catalyzed reactions but have also shown to offer photophysical and electrochemical properties. The metalation/transmetalation strategy using [Zr(NMe2)4] as initial metalating reagent offers an efficient approach to the preparation of CCC-NHC pincer complexes of the late transition metals such as Rh and Ir. In the process of investigating an intermediate and the mechanism of the metalation/transmetalation to Rh sequence, a mixed valent bimetallic CCC-NHC pincer Rh complex with two chloro ligands bridged between a [(CCC-NHC)Rh(III)] and a [Rh(I)(COD)] fragment was isolated and fully characterized for the first time. The investigation of the Rh(III)/Rh(I) bimetallic intermediate in the CCC-NHC pincer metalation/transmetalation methodology led to an improved stoichiometric synthesis of series of CCC-NHC pincer Rh complexes. The CCC-NHC pincer Rh complexes were characterized with 1H and 13C NMR spectroscopy, ESI-TOF MS and single crystal X-ray diffraction. The catalytic activity of the series of CCC-NHC pincer Rh complexes were evaluated. All the CCC-NHC pincer Rh precatalysts were found to promote the dehydrogenative silylation of vinylarenes with Et3SiH to form the corresponding (E)-vinylsilanes as the major silylation product under solvent-free conditions. The catalytic system displays wide substrate scope. Electron rich and electron deficient vinylarenes were well tolerated affording the corresponding vinyl silanes in good yields (65-86%). Mechanistic investigations indicated that Rh(III) center was responsible for the catalytic performance. The CCC-NHC pincer ligand architecture plays a role in achieving good regio- and stereoselectivities. Also, the complexes were evaluated as precatalysts towards hydrosilylation of aryl- and alkyl alkenes. The precatalysts, [(BuCiCiCBu)RhCl(µ-Cl)2Rh(COD)] and [(BuCiCiCBu)RhCl(µ-Cl)]2, were found to promote highly regioselective anti-Markovnikov hydrosilylation of aryl- and alkyl alkenes with excellent selectivity (>99%) using Et3SiH or PhMe2SiH as silane source and acetonitrile as solvent. Straight chain alkyl alkenes were tolerated without undergoing isomerization as it is the case with most known hydrosilylation catalyst systems. We extended the improved stoichiometric metalation/transmetalation methodology towards the synthesis of 1,3-di(1H-1,2,4-triazol-1-yl)benzene-based pincer Rh complexes. A series of 1,1'-(1,3-phenylene)bis(4-hexyl-1H-1,2,4-triazol-4-ium) salts were synthesized. Metalation/transmetalation of 1,1'-(1,3-phenylene)bis(4-hexyl-1H-1,2,4-triazol-4-ium) diiodide salt was successfully demonstrated to synthesize novel triazole-based CCC-NHC pincer Rh complexes.

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Die vorliegende Arbeit beschäftigt sich mit der Synthese von Pincer-Ligandenvor-läufern mit fluorierten Alkylketten –(CH2)2Rf6 (Rf6 = C6F13) an Sauerstoff- bzw. Phosphorhaftatomen. Darüber hinaus stehen die Bildung hochfluorierter Lithium-, Palladium-, Ruthenium- sowie Aluminium-Pincer-Komplexe und die Reaktivitäts-studien für diese neuartigen Komplexe im Fokus. Für vergleichende Untersuchungen war ebenso die Synthese der analogen, nicht fluorierten Verbindungen von Interesse. Eine Mischung aus in situ hergestelltem (NC5H3)-1,3-(CH2P((CH2)2(CF2)5CF3)2)2 (13) und [Ru(2Me-C3H4)2(cod)] kann die Dehydrogenierung von Cyclooctan bei vergleichsweise niedrigen Temperaturen von 80 °C katalysieren. Interessant ist die je nach Lösungsmittel unterschiedliche Produktbildung. Die Lithium- und Aluminiumkomplexe [Li(C6H3-2,6-(CH2O(CH2)2(CF2)5CF3)2)] (21), [Li(C6H3 2,6 (CH2OCH3)2)] (22), [Al((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)(CH3)2] (28), [Al((C6H3)-2,6-(CH2OCH3)2)I2] (29), [Al((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)I2] (31) wurden erfolgreich synthetisiert und charakterisiert. Mittels [Al((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)I2] (31) konnten diverse aromatische Verbindungen wie Benzol, Toluol oder Pentafluorbenzol dehydrogenierend gekuppelt werden. Weiterhin wurden die Palladiumkomplexe [Pd(Cl)((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)] (34) und [Pd(NCCH3)((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)][PF6] (36), [Pd(Cl)((C6H3)-2,6-(CH2OCH3)2] (37) und [Pd(NCCH3)((C6H3)-2,6-(CH2OCH3)2][PF6] (38) hergestellt und charakterisiert. / The current thesis is concerned with the syntheses of pincer ligand precursors with fluorinated alkyl chains –(CH2)2Rf6 (Rf6 = C6F13), the so called „ponytails“, at oxygen or phosphorous donor atoms. Furthermore, this work focuses on the formation of highly fluorinated lithium, palladium, ruthenium or alumina pincer complexes and considering reactivity studies of these novel compounds. For comparative investigations the syntheses of the analog non-fluorinated compounds was of great interest. A mixture of in situ synthesized (NC5H3)-1,3-(CH2P((CH2)2(CF2)5CF3)2)2 (13) and [Ru(2Me-C3H4)2(cod)] catalyses the dehydrogenation of cyclooctane at relatively low temperatures of 80 °C. Depending on the used solvent cyclooctene or cyclooctatriene can be received as the single product, respectively. The lithium and alumina complexes [Li(C6H3-2,6-(CH2O(CH2)2(CF2)5CF3)2)] (21), [Li(C6H3 2,6 (CH2OCH3)2)] (22), [Al((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)(CH3)2] (28), [Al((C6H3)-2,6-(CH2OCH3)2)I2] (29), and [Al((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)I2] (31) were synthesized and characterized succesfully. With the complex [Al((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)I2] (31) a diversity of aromatic compounds like benzene, toluene or pentafluorobenzene can be coupled after dehydrogenation. Moreover, the palladium complexes [Pd(Cl)((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)] (34), [Pd(NCCH3)((C6H3)-2,6-(CH2O(CH2)2(CF2)5CF3)2)][PF6] (36), [Pd(Cl)((C6H3)-2,6-(CH2OCH3)2] (37) and [Pd(NCCH3)((C6H3)-2,6-(CH2OCH3)2][PF6] (38) were synthesized and characterized.

Our group has been developing normal CCC-NHC pincer complexes for catalysis and OLED applications. However, synthesizing the abnormal analogs has been challenging due to the difficulty in accessing the ligand precursors. This study addresses these challenges, marking a significant step in CCC-NHC pincer chemistry. The abnormal CCC-NHC proligands were synthesized through Ullmann-type coupling of 2-phenylimidazole to 1,3-dibromobenzene. The intermediate 1,3-bis(2-phenylimidazole)benzene was alkylated with 1-iodobutane to obtain the 1,3-bis(N-butyl-2-phenylimidazole)benzene diiodide salt. The proligands 1,3-bis(N-butyl-2-phenylimidazole)benzene dichloride/diiodide were metalated with [Zr(NMe2)4] and transmetalated to group 10 metals (Ni, Pd, Pt) using [NiCl2(glyme)], [Pd(COD)Cl2], and [Pt(COD)Cl2]. Electrospray ionization of the CCC-aNHC pincer complexes [(BuCa-iCa-iCBu)MX] (M = Ni, Pd, Pt, X = Cl, I) in acetonitrile generated dinitrogen adducts [(BuCa-iCa-iCBu)M-N2]+, representing a rare example of group 10 dinitrogen complexes. The coordination of N2 to the cationic species means the pincer ligand provides the required electron density to the metals to stabilize the N2 through π-backbonding. The redox chemistry of NiII and PdII complexes bearing the super electron donating CCC-aNHC pincer ligand was investigated. The PdII complexes were cleanly oxidized with two electron oxidants, such as iodobenzene dichloride (PhICl2). The oxidation of the PdII complex with a half equiv of the oxidants gave mixed valent PdII/PdIV dimer as a thermodynamically preferred product. The oxidation of the CCC-aNHC NiII chloride complex with PhCl2 produced unstable NiIII species. However, utilizing anhydrous CuCl2 as the oxidant yielded a bis-ligated NiIV complex, a seemingly common occurrence among the first-row metals (Fe and Co). Emissive square planar Pt complexes have been utilized to produce OLEDs, but those with halides pose potential threats due to the electrochemical instability of halide complexes. Thus, it is highly desirable that halide-free square planar Pt complexes that maintain high molecular rigidity are developed. The CCC-aNHC pincer Pt halide complexes were emissive when irradiated with UV light. The pincer Pt halide complexes were converted to Pt azolate complexes and retained their emission properties. Substituting halides on Pt complexes with azolates increases the PLQY from 7 % to 24 % and the emission lifetimes from 1.0 μs to 1.4 μs in the solid states.

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Plusieurs nouveaux complexes pinceurs de cobalt et de nickel ont été préparés avec le ligand pinceur de type POCOP : 2,6-(i-Pr2PO)2C6H4. Dans le cas du cobalt, une nouvelle voie de synthèse a été développée. Contrairement au cas du nickel, il s’agit ici de cobalt au degré d’oxydation +III. Les composés obtenus sont paramagnétiques. En outre, le dérivé bromé est instable à la lumière et se décompose en perdant un brome pour former le complexe pinceur de Co(II). La réactivité de ces complexes a été étudiée. Pour ce qui est du nickel, la catalyse de l’hydroamination a été élargie aux dérivés de l’acrylonitrile et aux amines aromatiques. En outre, la réaction d’hydroaryloxylation a été étudiée dans les mêmes conditions. Enfin, avec le 4-cyanostyrène et le cinnamonitrile, la formation d’amidines a été observée. Un complexe pinceur portant cette amidine a été isolé. Enfin, le cation réagit avec des anions fortement coordonnants tels le cyanure ou l’isocyanate. En outre, l’anion triflate peut être déplacé par l’eau, l’acrylonitrile et ses dérivés. Enfin, une réactivité particulière a été observée avec la morpholine, l’acétone et un mélange 1:1 aniline/triéthylamine. / A large variety of new POCOP pincer type complexes of cobalt and nickel have been prepared. All those complexes are based on the following POCOP pincer type ligand: 2,6-(i-Pr2PO)2C6H4 In the case of cobalt, a new synthetic pathway has been developped. Unlike nickel, complexes containing cobalt in the +III oxidation state are obtained, the mechanism of their formation remains unknown. These complexes are paramagnetic. The dibromo derivative is light-sensitive, decomposing by losing a bromine to form the Co(II) pincer complex. The reactivity of those complexes has been studied. Concerning nickel, the catalyzed hydroamination has been extended to the derivates of acrylonitrile, crotonitrile and methacrylonitrile and to aromatic amines. Moreover, hydroaryloxylation reaction has been studied under the same conditions. Finally, amidines formation was obtained with 4-cyanostyrene and with cinnamonitrile. A pincer complex bearing this amidine moiety has been isolated. The cationic complex reacts with strong coordinating anions like cyanide and isocyanate. Moreover, the triflate anion is displaced by water, acrylonitrile and acrylonitrile derivates. Finally, a particular reactivity has been observed with morpholine, acetone and a 1:1 mixture of aniline and triethylamine.