Syntheses and Reactions of Derivatives of (Pyrrolylaldiminato)germanium(II) and -Aluminum(III)

(Pyrrolylaldiminato)­germanium­(II) chloride, LGeCl (<b>1</b>), was prepared by reacting LLi (L = 2-(ArNCH)-5-<i>t</i>BuC₄H₂N; Ar = 2,6-<i>i</i>Pr₂C₆H₃) with 1 equiv of GeCl₂·(dioxane). Treatment of LGeCl (<b>1</b>) with KO<i>t</i>Bu or LiN­(H)Ar yielded LGeR (R = O<i>t</i>Bu (<b>2</b>), N­(H)Ar (<b>3</b>)) by halide metathesis. (Pyrrolylaldiminato)­methylaluminum chloride, LAlMe­(Cl) (<b>4</b>), was obtained from the reaction of LLi and MeAlCl₂ or by treating LH with Me₂AlCl in toluene. Treatment of LH with Me₂AlCl or AlCl₃ in Et₂O at −18 °C resulted in the 1:1 adducts LH·AlMe₂Cl (<b>5</b>) and LH·AlCl₃ (<b>5</b>′), respectively. Further reaction of <b>4</b> with 2 equiv of LiNEt₂ led to the insertion of the NEt₂ group into the CN bond together with the elimination of LiCl, to afford L′(NEt₂)­AlMe­(NEt₂)­Li­(THF) (<b>6</b>). Similarly, treatment of <b>4</b> with 2 equiv of LiPPh₂(THF)₂ gave L′(PPh₂)­AlMe­(OC₄H₈-PPh₂)­Li­(THF)₂ (<b>7</b>) accompanied by ring opening of THF. Single-crystal X-ray structure determinations revealed that <b>3</b> and <b>4</b> each contained enantiomeric pairs, while <b>6</b> and <b>7</b> each adopted a single enantiomer

Synthesis and Characterization of Coinage Metal Aluminum Sulfur Species

The synthesis of heterobimetallic cluster with the Al–S–M (M = Cu and Ag) structural unit has been realized for the first time by the reaction of aluminum-dithiol LAl­(SH)₂ (L = HC­[C­(Me)­N­(Ar)]₂, Ar = 2,6-<i>i</i>Pr₂C₆H₃) with (MesCu)₄ and (MesAg)₄ (Mes = 2,4,6-Me₃C₆H₂), respectively. The isolated clusters exhibit core structures of Al₂Cu₄S₄ and Al₄Ag₈S₈, respectively. During the formation of the [LAl­(SAg)₂]₄, a side product of LAlS₆ is formed. However, the reaction of LAl­(SH)₂ with excess of sulfur and (MesAg)₄ resulted in the formation of LAlS₄ as the only product soluble in organic solvents. Both of them represent rare examples of aluminum polysulfides. All compounds were characterized by spectroscopic methods and single crystal X-ray diffraction studies

Studies of the Ligand Effect on the Synthesis of Dialuminoxanes by Various β-Diketiminato Ligands

Reactions of LH (L = HC­[C­(Me)­N­(2,6-Me₂C₆H₃)]₂) with Me_<i>n</i>AlCl_3–<i>n</i> in diethyl ether afforded the adducts LH·AlMe_<i>n</i>(Cl)_3–<i>n</i> (<i>n</i> = 2, <b>3</b>; 1, <b>4</b>; 0, <b>5</b>) in good yields. Treatment of <b>3</b> at elevated temperatures in toluene resulted in LAlMeCl (<b>2</b>) by intramolecular elimination of methane. The controlled hydrolysis of LAlMeCl (<b>2</b>) with equimolar amounts of water in the presence of N-heterocyclic carbene (NHC) gave a mixture of [LAl­(Me)]₂(μ-O) (<b>7</b>) and dimeric [LAlMe­(μ-OH)]₂ (<b>8</b>). A convenient route for the preparation of [LAlMe­(μ-OH)]₂ (<b>8</b>) was the NHC-assisted controlled hydrolysis of LAlMeI (<b>9</b>). Stepwise hydrolysis of LAlH₂ (<b>11</b>) gave dialuminoxane hydride [LAl­(H)]₂(μ-O) (<b>12</b>) and dialuminoxane hydroxide [LAl­(OH)]₂(μ-O) (<b>13</b>), respectively. Anhydrous treatment of LAlCl₂ (<b>1</b>) or LAlMeCl (<b>2</b>) with Ag₂O afforded chlorinated dialuminoxane [LAl­(Cl)]₂(μ-O) (<b>14</b>) and [LAl­(Me)]₂(μ-O) (<b>7</b>), respectively

Reactivity Studies of Heteroleptic Silylenes with N₂O

Reaction of heteroleptic silylenes LSiX (L = PhC­(N<i>t</i>Bu)₂; X = PPh₂ (<b>1</b>), NPh₂ (<b>2</b>), NMe₂ (<b>3</b>), O<i>t</i>Bu (<b>4</b>)) with N₂O resulted in the oxidized dimeric product [LSi­(X)­(μ-O)]₂ (X = PPh₂ (<b>5</b>), NPh₂ (<b>6</b>), NMe₂ (<b>7</b>), O<i>t</i>Bu (<b>8</b>)), which contains a four-membered Si₂O₂ ring. Compounds <b>5</b>–<b>8</b> were characterized by spectroscopic and spectrometric techniques. The molecular structures of <b>5</b>–<b>8</b> were established by single-crystal X-ray structure analysis

Reactivity Studies of Heteroleptic Silylenes with N₂O

Reaction of heteroleptic silylenes LSiX (L = PhC­(N<i>t</i>Bu)₂; X = PPh₂ (<b>1</b>), NPh₂ (<b>2</b>), NMe₂ (<b>3</b>), O<i>t</i>Bu (<b>4</b>)) with N₂O resulted in the oxidized dimeric product [LSi­(X)­(μ-O)]₂ (X = PPh₂ (<b>5</b>), NPh₂ (<b>6</b>), NMe₂ (<b>7</b>), O<i>t</i>Bu (<b>8</b>)), which contains a four-membered Si₂O₂ ring. Compounds <b>5</b>–<b>8</b> were characterized by spectroscopic and spectrometric techniques. The molecular structures of <b>5</b>–<b>8</b> were established by single-crystal X-ray structure analysis

Syntheses and Reactions of Derivatives of (Pyrrolylaldiminato)germanium(II) and -Aluminum(III)

(Pyrrolylaldiminato)­germanium­(II) chloride, LGeCl (<b>1</b>), was prepared by reacting LLi (L = 2-(ArNCH)-5-<i>t</i>BuC₄H₂N; Ar = 2,6-<i>i</i>Pr₂C₆H₃) with 1 equiv of GeCl₂·(dioxane). Treatment of LGeCl (<b>1</b>) with KO<i>t</i>Bu or LiN­(H)Ar yielded LGeR (R = O<i>t</i>Bu (<b>2</b>), N­(H)Ar (<b>3</b>)) by halide metathesis. (Pyrrolylaldiminato)­methylaluminum chloride, LAlMe­(Cl) (<b>4</b>), was obtained from the reaction of LLi and MeAlCl₂ or by treating LH with Me₂AlCl in toluene. Treatment of LH with Me₂AlCl or AlCl₃ in Et₂O at −18 °C resulted in the 1:1 adducts LH·AlMe₂Cl (<b>5</b>) and LH·AlCl₃ (<b>5</b>′), respectively. Further reaction of <b>4</b> with 2 equiv of LiNEt₂ led to the insertion of the NEt₂ group into the CN bond together with the elimination of LiCl, to afford L′(NEt₂)­AlMe­(NEt₂)­Li­(THF) (<b>6</b>). Similarly, treatment of <b>4</b> with 2 equiv of LiPPh₂(THF)₂ gave L′(PPh₂)­AlMe­(OC₄H₈-PPh₂)­Li­(THF)₂ (<b>7</b>) accompanied by ring opening of THF. Single-crystal X-ray structure determinations revealed that <b>3</b> and <b>4</b> each contained enantiomeric pairs, while <b>6</b> and <b>7</b> each adopted a single enantiomer

Reactivity of Stable Heteroleptic Silylene PhC(N<i>t</i>Bu)₂SiNPh₂ toward Diazobenzene and <i>N</i>‑Benzylidineaniline

The reaction of heteroleptic silylene LSiNPh₂ [L = PhC­(N<i>t</i>Bu)₂] with diazobenzene afforded product <b>6</b>. This involves one <i>o</i>-C–H bond activation at one of the phenyl groups of diazobenzene and migration of this hydrogen atom from the phenyl ring to one of the nitrogen atoms, which leads to the formation of the new C–Si and N–Si bonds. The reaction of benzylidineaniline with LSiNPh₂ results in the oxidative addition of the three-membered silaaziridine derivative <b>7</b>. Compounds <b>6</b> and <b>7</b> were fully characterized by elemental analysis, multinuclear NMR spectroscopy, and EI-MS spectrometry. The molecular structures of compounds <b>6</b> and <b>7</b> were established unequivocally by single-crystal X-ray structural analysis

Coinage Metals Binding as Main Group Elements: Structure and Bonding of the Carbene Complexes [TM(cAAC)₂] and [TM(cAAC)₂]⁺ (TM = Cu, Ag, Au)

Quantum chemical calculations using density functional theory have been carried out for the cyclic (alkyl)­(amino)­carbene (cAAC) complexes of the group 11 atoms [TM­(cAAC)₂] (TM = Cu, Ag, Au) and their cations [TM­(cAAC)₂]⁺. The nature of the metal–ligand bonding was investigated with the charge and energy decomposition analysis EDA-NOCV. The calculations show that the TM–C bonds in the charged adducts [TM­(cAAC)₂]⁺ are significantly longer than in the neutral complexes [TM­(cAAC)₂], but the cations have much higher bond dissociation energies than the neutral molecules. The intrinsic interaction energies Δ<i>E</i>_int in [TM­(cAAC)₂]⁺ take place between TM⁺ in the ¹S electronic ground state and (cAAC)₂. In contrast, the metal–ligand interactions in [TM­(cAAC)₂] involve the TM atoms in the excited ¹P state yielding strong TM p­(π) → (cAAC)₂ π backdonation, which is absent in the cations. The calculations suggest that the cAAC ligands in [TM­(cAAC)₂] are stronger π acceptors than σ donors. The trends of the intrinsic interaction energies and the bond dissociation energies of the metal–ligand bonds in [TM­(cAAC)₂] and [TM­(cAAC)₂]⁺ give the order Au > Cu > Ag. Calculations at the nonrelativistic level give weaker TM–C bonds, particularly for the gold complexes. The trend for the bond strength in the neutral and charged adducts without relativistic effects becomes Cu > Ag > Au. The EDA-NOCV calculations suggest that the weaker bonds at the nonrelativistic level are mainly due to stronger Pauli repulsion and weaker orbital interactions. The NBO picture of the C–TM–C bonding situation does not correctly represent the nature of the metal–ligand interactions in [TM­(cAAC)₂]

Studies of the Ligand Effect on the Synthesis of Dialuminoxanes by Various β-Diketiminato Ligands

Reactions of LH (L = HC­[C­(Me)­N­(2,6-Me₂C₆H₃)]₂) with Me_<i>n</i>AlCl_3–<i>n</i> in diethyl ether afforded the adducts LH·AlMe_<i>n</i>(Cl)_3–<i>n</i> (<i>n</i> = 2, <b>3</b>; 1, <b>4</b>; 0, <b>5</b>) in good yields. Treatment of <b>3</b> at elevated temperatures in toluene resulted in LAlMeCl (<b>2</b>) by intramolecular elimination of methane. The controlled hydrolysis of LAlMeCl (<b>2</b>) with equimolar amounts of water in the presence of N-heterocyclic carbene (NHC) gave a mixture of [LAl­(Me)]₂(μ-O) (<b>7</b>) and dimeric [LAlMe­(μ-OH)]₂ (<b>8</b>). A convenient route for the preparation of [LAlMe­(μ-OH)]₂ (<b>8</b>) was the NHC-assisted controlled hydrolysis of LAlMeI (<b>9</b>). Stepwise hydrolysis of LAlH₂ (<b>11</b>) gave dialuminoxane hydride [LAl­(H)]₂(μ-O) (<b>12</b>) and dialuminoxane hydroxide [LAl­(OH)]₂(μ-O) (<b>13</b>), respectively. Anhydrous treatment of LAlCl₂ (<b>1</b>) or LAlMeCl (<b>2</b>) with Ag₂O afforded chlorinated dialuminoxane [LAl­(Cl)]₂(μ-O) (<b>14</b>) and [LAl­(Me)]₂(μ-O) (<b>7</b>), respectively

Synthesis and Characterization of Heterobimetallic Al–O–Cu Complexes toward Models for Heterogeneous Catalysts on Metal Oxide Surfaces

The β-diketiminato aluminum-monohydroxide and -dihydroxide were reacted with tetrameric (CuMes)₄ (Mes = 2,4,6-Me₃C₆H₂) to prepare Cu­(I) complexes bearing the Al–O–Cu moiety. All complexes are characterized by elemental analysis, nuclear magnetic resonance, and single-crystal X-ray diffraction. The reaction of aluminum–monohydroxide LAlR­(OH) (L = HC­[C­(Me)­N­(Ar)]₂; Ar = 2,6-<i>i</i>Pr₂C₆H₃; R = Me, Et) with (CuMes)₄ afforded the Cu­(I) alumoxane [LAl­(R)­OCu·MesCu]₂ (R = Me, <b>1</b>; Et, <b>2</b>). Using the aluminum-dihydroxide LAl­(OH)₂ as the precursor, the dimeric [LAl­(OH)­OCu·MesCu]₂ (<b>3</b>) was isolated, bearing one reactive OH group on each Al center. When the reaction of LAl­(OH)₂ with (CuMes)₄ was carried out at 70 °C, the dimeric octanuclear Cu­(I) compound [LAl­(OCu·MesCu)₂]₂ (<b>4</b>) was formed, where two residual Mes groups are located at the neighboring position on each of the two (OCu·MesCu)₂ squares. Compound <b>4</b> can be alternatively obtained by reacting <b>3</b> with 1 equiv of (CuMes)₄ to demonstrate the stepwise assembly of the Cu­(I) alumoxanes