Organozinc Siloxide-Hydrazide Aggregates [(RZn)₄(NHNMe₂)_x(OSiMe₃)_{(4 – x)}]

Abstract

The reaction of dialkylzinc compounds R 2 Zn (R = Me, Et) with N,N-dimethylhydrazine and trimethylsilanol in a 4 : 2 : 2 ratio leads to the formation of tetra(alkylzinc) tris-siloxide monohydrazide aggregates, [(RZn) 4 (NHNMe 2 )(OSiMe 3 ) 3 ] [R = Me (1) and Et (2)]. These compounds are aggregates of mirror symmetry, containing the novel Zn 4 N 2 O 3 core. Both compounds have been characterised by 1 H, 13 C and 29 Si NMR and IR spectroscopy, by mass spectrometry and by elemental analysis, and 2 also by X-ray crystallography. The structure can be derived from a heterocubane, in which one anionic vertex is replaced by an NHNMe 2 group contributing two N atoms to the core constitution. By applying a ratio of hydrazine : silanol of 2 : 1 in a reaction with R 2 Zn (R = Me, Et, iPr), compounds of the general formula [(RZn) 4 (NHNMe 2 ) 2 (OSiMe 3 ) 2 ] [R = Me (3), Et (4), iPr (5)] are obtained. These aggregates contain a Zn 4 N 4 O 2 core. Upon employing a hydrazine : silanol ratio of 5 : 1 in a reaction with diisopropyl zinc, the compound [(iPrZn) 4 (NHNMe 2 ) 3 (OSiMe 3 )] results, containing a Zn 4 N 6 O unit. Compounds 3 -6 have been characterised by 1 H, 13 C and 29 Si NMR and IR spectroscopy, by mass spectrometry and by elemental analysis. The topologic relationship between the pure hydrazides [(RZn) 4 (NHNMe 2 ) 4 ], the mixed aggregates [(RZn) 4 (NHNMe 2 ) 3 (OR')], [(RZn) 4 (NHNMe 2 ) 2 (OR') 2 ] and [(RZn) 4 (NHNMe 2 ) 3 (OR') 3 ] and the pure alkoxides [(RZn) 4 (OR') 4 ] is discussed.

Modern concepts and methods in the chemistry of polyhedral metallasiloxanes

“…However, additional ligands are necessary in the majority of cases, (Fig. 35), such as an azoimide residue (99 [144]), amino group (100 [145]), acyl group (101 [146]), halogen (102 [147]), organophosphine (103 [148]), or isothiocyanate group (104 [149]. 103 [148] 104 [149] This is also true for the formation of polyhedral molecules containing only alkali metal ions, where these PHMSs are formed exclusively from organosilanolates (Fig.…”