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While the nucleophilic addition of ammonia to ketones is an archetypal reaction in classical organic chemistry, the reactivity of heavier group 14 carbonyl analogues (R2E=O; E=Si, Ge, Sn, or Pb) with NH3 remains sparsely investigated, primarily due to the synthetic difficulties in accessing heavier ketone congeners. Herein, we present a room‐temperature stable boryl‐substituted amidinato‐silanone {(HCDippN)2B}{PhC(tBuN)2}Si=O (Dipp=2,6‐iPr2C6H3) (together with its germanone analogue), formed from the corresponding silylene under a N2O atmosphere. This system reacts cleanly with ammonia in 1,2‐fashion to give an isolable sila‐hemiaminal complex {(HCDippN)2B}{PhC(tBuN)2}Si(OH)(NH2). Quantum chemical calculations reveal that the formation of this sila‐hemiaminal is crucially dependent on the nature of the ancillary ligand scaffold. It is facilitated thermodynamically by the hemi‐lability of the amidinate ligand (which allows for the formation of an energetically critical intramolecular N⋅⋅⋅HO hydrogen bond within the product) and is enabled mech‐anistically by a process in which the silanone initially acts in umpolung fashion as a base (rather than an acid), due to the strongly electron‐releasing and sterically bulky nature of the ancillary boryl ligand. [ABSTRACT FROM AUTHOR]

The reaction of the bulky EMind-based diarylgermylene, (EMind)2Ge: (1a) (EMind = 1,1,7,7-tetraethyl-3,3,5,5-tetramethyl-s-hydrindacen-4-yl), with pyridine N-oxide (Py+O-) initially formed the Py-coordinated diarylgermanone, (EMind)2-Ge(=O)(Py) (3a), which gradually converted to the 1,3,2,4-dioxadigermetane, (EMind)4Ge2(®-O)2 (4a), through the dimerization of the germanone, (EMind)2Ge=O (2a). The Ge=O double-bond in 3a reacted not only with H2O to give the germanediol, (EMind)2Ge(OH)2 (5a), but also with Py+O- to form the germanol, (EMind)2Ge(C5H4NO)(OH) (6a), via activation of the ortho CH bond. [ABSTRACT FROM AUTHOR]

A rare three‐coordinate germanone [IPrN]2Ge=O (IPrN=bis(2,6‐diisopropylphenyl)imidazolin‐2‐imino) was successfully isolated. The germanone has a rather high thermal stability in arene solvent, and no detectable change was observed at 80 °C for at least one week. However, high thermal stability of [IPrN]2Ge=O does not prevent its reactivity toward small molecules. Structural analysis and initial reactivity studies revealed the highly polarized nature of the terminal Ge=O bond. Besides, the addition of phenylacetylene, as well as O‐atom transfer with 2,6‐dimethylphenyl isocyanide make it a mimic of nucleophilic transition‐metal oxides. Mechanism for O‐atom transfer reaction was investigated via DFT calculations, which revealed that the reaction proceeds via a [2+2] cycloaddition intermediate. [ABSTRACT FROM AUTHOR]

Complexes of germanone containing formal Ge=O→M bonds (M=Zn, B, Ge, Sn) were isolated and characterized. The compounds were prepared through a novel synthetic route using a germanium μ-oxo dimer 3 as the starting material. This method circumvents the need to employ germanones to prepare complexes of germanones. [ABSTRACT FROM AUTHOR]

Dispersion corrected quantum-chemical calculations of the germanones [(Eind) 2 Ge O] ( I ), [((Tbt))(Tip)Ge O] ( II ) and [R 2 Ge O] ( III , R = Ph; IV , R = Me) were performed to evaluate the effect of noncovalent interactions on the dramatic stability of isolated germanone [(Eind) 2 Ge O]. The investigations have been carried at DFT, DFT-D3(BJ) and DFT-DDSC level with BP86, PW91, PBE density functionals. The dispersion-corrected geometry of the compound [(Eind) 2 Ge O] (Ge O = 1.668 Å) is in good agreement with the experimental geometry (Ge O = 1.6468(5) Å). The polarizations of the G C σ-bonds toward the carbon atoms and Ge O σ- and π-bonds toward oxygen atom decreases on going from I to IV . Due to the largest polarizations of these bonds in germanone ( I ), the Ge C and Ge O bond distances are longest in ( I ). The lowering in charge on oxygen atom in [(Eind) 2 Ge O] ( I ) retard its reactivity. The total contribution of Ge atom toward two Ge C bonds are 50.60% in I < 57.18% in II < 59.70% in III < 63.02% in IV . The Ge C bonds (longer Ge C bond distances, smaller Mayer Ge C bond orders, smaller values of BDE and interaction energy) in most stable germanone [(Eind) 2 GeO] ( I ) are weaker than the Ge C bonds in germanpnes ( II – IV ) and do not support the trends of relative stability of germanones ( I – IV ). The D3(BJ) dispersion energy is largest for germanone [(Eind) 2 GeO]. Thus, compared to small molecules, large molecules are stabilized by dispersion interactions. The dispersion interactions between R⋯R and between R⋯GeO support the trends of relative stability of germanones ( I – IV ). [ABSTRACT FROM AUTHOR]

H(2-n)X(n)A=Te (X=H, F, Cl and Br; A=C, Si and Ge; n=0-2), the novel heavy congeners of formaldehyde, have been studied in the gas phase using MP2/def2-TVZP and BP86/def2-TVZP methods. Emphasis has been laid on the bond strengths and the standard heats of formation (ΔHf°) of the mentioned telluro-ketones to reveal their thermodynamic stabilities and further assist in their isolations. The bond strengths have been evaluated in terms of the σ-bond energy, π-bond energy and the bond dissociation enthalpy, D°, using isodesmic reaction schemes. The methodology employed has satisfactorily reproduced the bond strengths and the ΔHf° of formaldehyde and silanone. The findings from this work indicate that the D° of the F2A=Te (A=C, Si and Ge) molecules are comparable to that of H2C=O and thus their respective stabilities are expected to be equivalent to that of formaldehyde. Besides, the fluorinated telluro-ketones are predicted to possess a unique thermodynamic stability since they have the most exothermic ΔHf° in their respective series while the H2A=Te ketones have the most endothermic ΔHf°. In addition, the silanetellones are found to be thermodynamically more stable than their corresponding telluroformaldehyde and germanetellone analogs. Since reported data for H(2-n)X(n)A=Te (X=H, F, Cl and Br; A=C, Si and Ge; n=0-2) is non-existent in terms of the thermodynamic data, the findings of this work should supplement the literature with reliable information. [ABSTRACT FROM AUTHOR]

Abstract: The formation of a new transient germa-alkyne Ar-GeSiMe3 [Ar=2,4-di-tert-butyl-6-(diisopropylaminomethyl)phenyl] is achieved by photolysis of the corresponding trimethylsilyldiazomethylgermylene ArGeC(N2)SiMe3 (2). The germa-alkyne is characterized by trapping reactions with H2O and an equimolar mixture of tert-butanol and water. The respective adducts, the gem-germanediol 5 and the alkoxygermanol 4 have been fully characterized by spectroscopic methods. A study of the mechanism is proposed and in both cases, the addition involves the transient formation of a germanone. The structures of 2 and 5 are determined by single-crystal X-ray diffraction. [Copyright &y& Elsevier]

Vacuum pyrolysis of 3-sila-3,3′-spirobi(6-oxabicyclo[3.1.0]hexanes) leads to the formation of monomeric silicon dioxide and 1,3-butadienes, whereas under the same conditions 3-germa-3,3′-spirobi(6-oxabicyclo[3.1.0]hexanes) afford germanium monoxide, the corresponding divinyl ethers, and 1,3-butadienes. A multistage mechanism of pyrolytic decomposition of the above spirobicyclohexanes was proposed on the basis of experimental data and calculations. The different behavior of the silicon and germanium compounds having similar structures can be explained by an increase in the bivalent state stability and by a decrease in the energy of the metal-oxygen double bond on the transition from silicon to germanium. [ABSTRACT FROM AUTHOR]

Am Ende der Reise: Mehr als 100 Jahre nach den ersten Syntheseversuchen eines stabilen Silanons wurde dieses Ziel durch die Herstellung eines Metallsilanonkomplexes erreicht (siehe Schema). Um die schwer erzeugbare SiO ‐ Bindung zu stabilisieren, wurde eine elektronenreichen Chromeinheit in Verbindung mit einem sterisch anspruchsvollen gesättigten N ‐ heterocyclischen Carben genutzt. [ABSTRACT FROM AUTHOR]