Synthesis and selected properties of nonahalogenated 2-ammonio-decaborate anions and their derivatives substituted at N-centre

Publication date: Available online 1 March 2018 Source:Journal of Organometallic Chemistry Author(s): Suzan El Anwar, Josef Holub, Oleg Tok, Tomáš Jelínek, Zdeňka Růžičková, Lukáš Fojt, Veronika Šolínová, Václav Kašička, Bohumír Grüner New preparative methods for halogenation of the cage producing the corresponding [2-NH3-B10X9]- species (2 - to 4 - , X = Cl, Br, I) have been developed using halogenations by elemental halogens in a glass pressure vessel. Compared to similar icosahedral species of formulation [1-H3N-B12X11]- (X = Cl, Br), the N-alkylation reactions in 10-vertex series proceed significantly more easily. The reason for this difference is conceivably due to the two orders of magnitude lower basicity of the amino group, with pKa values in the interval from 9.27 to 8.37, and slightly lower steric strain around the reaction centre. Thus methylations with MeI under mild conditions provided the whole series of corresponding quarternary amines of the formulation [2-Me3N-B10X9]- (5 - to 7 - , X = Cl, Br, I). The effect of the steric strain of the surrounding halogens on the reactivity at the NH3- centre could then be better seen from reactions with bulkier benzyl bromide. Under comparable conditions, these reactions resulted in the ready formation of disubstituted compounds in case of X = Cl (8 - ), mixture of mono and disubstituted derivatives for X = Br (9 - , 10 - ) or in monosubstited product for X = I (11 - ) onl...

Source: Journal of Organometallic Chemistry - March 2, 2018 Category: Chemistry Source Type: research