- TRIMESITYLGERMYLAMINE Mes3GeNH2: SYNTHESES, STRUCTURE, PROPRIETES
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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.
- Riviere-Baudet, Monique,Morere, Alain,Onyszchuk, Mario,Satge, Jacques
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- Synthesis, reactivity and crystal structure of trimesitylgermylamine, Mes3GeNH2
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Trimesitylgermylamine, Mes3GeNH2, prepared in high yield by the coupling of Mes3GeCl (Mes = 2,4,6-Me3C6H2) with NaNH2 or LiNH2, has been fully characterized by 1H and 13C NMR, IR and mass spectrometry.It is a rare example of a stable primary germylamine, melting at 166 deg C, which is only slowly cleaved by H2O, CH3OH, HCl or phenol, indicating tht the central Ge atom is protected from attack by the mesityl groups.Unlike other germylamines, Mes3GeNH2 reacts with tBuCOCl to give the N-substituted amide, Mes3GeNHCOtBu, rather than Mes3GeCl.Preliminary X-ray crystallographic analyses reveal that the Ge atom has approximate tetrahedral coordination with an average Ge-C bond length of 1.978(3) Angstroem and a Ge-N bond length of 1.854(3) Angstroem, and crowding around the Ge atom so that it is shielded from attack by approaching reactants.
- Riviere-Baudet, Monique,Morere, Alain,Britten, James F.,Onyszchuk, Mario
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