145296-91-9Relevant academic research and scientific papers
Mesitylpseudohalogermanes Mes2Ge(CN)2 and Mes3GeX (X=CN, NCS, N3, NCO and OH; Mes=2,4,6-trimethylphenyl): Syntheses, crystal and molecular structures
Hihara, Goro,Hynes, Rosemary C.,Lebuis, Anne-Marie,Rivière-Baudet, Monique,Wharf, Ivor,Onyszchuk, Mario
, p. 276 - 285 (2007/10/03)
The crystal and molecular structures of the mesitylpseudohalogermanes, Mes2Ge(CN)2 (Mes=2,4,6-trimethylphenyl) and Mes3GeX (X=CN, NCS, N3, NCO, or OH), have been determined by X-ray diffraction methods; the isocyanate and hydroxide crystallise as a 1:1 hydrogen-bonded complex. All are covalent monomers free from pseudohalogen bridging, and all except the cyanides and hydroxide are N-bonded to germanium. Each Ge atom is four-coordinate in a distorted tetrahedral geometry, as evident from (mes)-Ge-(mes) angles between 112 and 120°, which are attributed to the sterically demanding mesityl groups. The greatest distortion is displayed by Mes2Ge(CN)2, for which the NC-Ge-CN angle of 97.8(3)° and (mes)-Ge-(mes) angle of 119.8(3)° are also consistent with the bulky mesityl groups and the small steric requirements of the cyano groups. The Ge-N-Y angles show a distinctive trend, decreasing from 173.3(5)° for the isothiocyanate (Y=CS), through 153.5(5)° for the isocyanate (Y=CO), to 119.0(7)° for the azide (Y=NN), an effect attributed to differences in electronic structure of the pseudohalo ligands. The geometries of the compounds examined here are compared with those of some other tri- and dimesityl-Group 14 metal derivatives as well as related phenylgermanium compounds.
TRIMESITYLGERMYLAMINE Mes3GeNH2: SYNTHESES, STRUCTURE, PROPRIETES
Riviere-Baudet, Monique,Morere, Alain,Onyszchuk, Mario,Satge, Jacques
, p. 75 - 90 (2007/10/02)
Sterically hindered trimesitylgermylamine is a rare example of a stable primary germylamine.X-ray structural data show that germanium is shielded from nucleophilic attack by the surrounding mesityl groups.Nitrogen is still accessible, and the only reactions which occur are those in which the first step of the transition state proceeds through an electrophilic attack on nitrogen.With acid chlorides, Mes3GeNH2 reacts mainly as a primary amine forming the corresponding N-germylamides.The primary amine behaviour is also evident in the reaction with aldehydes.However, functional hydrogen cannot be substituted by lithium, probably because of steric hindrance which prevents the approach of an organolithium derivative.Insertion reactions into the Ge-N bond are difficult.Carbon dioxide and disulfide react only upon heating and yield trimesitylgermyliso- or isothiocyanates (Mes3GeN=C=X; X = O, S) through thermal degradation of the carbamate or dithiocarbamate initially formed. 3,5-di-tert-butylorthoquinone does not form an adduct with Mes3GeNH2, but is slowly transformed into 3,5-di-tert-butylorthocatechol.In spite of its steric hindrance, the trimesitylgermylamino group failed to stabilize a N-germylated germa-imine since the precursor Mes3Ge(Cl)NH-GeMes3 is not stable and gave cyclodigermazane (Mes2GeNH)2 and trimesitylgermyl chloride through Ge-Cl/Ge-N exchange reactions. Key words: Trimesitylgermylamine; 4-methyl 1-trimesitylgermoxy-benzene; N-trimesitylgermyl 2,2-dimethylpropanamide; trimesitylgermylisocyanate; trimesitylgermylisothiocyanate; tetramesitylcyclodigermazane.
