Lithium- [N-di-tert-butylfluorsilyl-N′,Ν′-dimethyl-hydrazid] -Synthese, Kristallstruktur und Reaktivität / Lithium (N-di-tert-butylfluorosilyl-N′,N′-dimethyl)hydrazide -Synthesis, Crystal Structure and Reactivity

Abstract

Di-tert-butyldifluorosilane reacts with N-lithium-N′,N′-dimethylhydrazine in a molar ratio 1:1 to yield the N-di-tert-butylfluorosilyl-N′,N′-dimethylhydrazine 1. The lithium derivative of 1 (2) forms a dimer with the nitrogen atoms coordinated “side-on” to the lithium atoms. The silylation with Me3SiCl gives product 3. Heating 2 in a vacuum leads to the cyclodisilazane derivative 4. A bis(hydrazino)fluoroborane (5) is obtained in the reaction of 2 with trifluoroborane-etherate.

Structural Diversity of Lithium Sulfenamides: 7Li NMR Studies in Solution and Crystal Structures of [Li2(η2-(CH3)3C−NS−C6H4CH3-4)2(THF)2] and [Li2(η1-4-CH3C6H4−NS−C6H4CH3-4)2(THF)4]

“…A ligand that contains the additional donor atom (X) directly bound to nitrogen could be considered as the shortest case of a chelating amide; the proximity to the metal favors the η 2 binding mode (Chart , I ) over the η 1 mode (Chart , II ). Such coordination has been observed in [Li 2 ((CH 3 ) 3 Si−N−N(Si(CH 3 ) 3 )) 2 ] ( 7 ), [Li 2 ((CH 3 ) 2 ((CH 3 ) 3 C)Si−N−N(H)Si(C(CH 3 ) 3 )(CH 3 ) 2 ) 2 (THF) 2 ] ( 8 ), [Li 2 ((CH 3 ) 3 Si−N−N(H)C(CH 3 ) 3 ) 2 (THF) 2 ] ( 9 ), [Li 2 ((CH 3 ) 3 Si−N−N(CH 2 C 6 H 5 )Si(CH 3 ) 3 ) 2 ] ( 10 ), [Li 2 (C 6 H 5 −N−N(H)Si(CH 3 ) 3 ) 2 (Et 2 O) 2 )] ( 11 ), and [Li 2 (F((CH 3 ) 3 C) 2 Si−N−N(CH 3 ) 2 ) 2 (THF) 2 ] ( 12 ) . Softer X atoms are less effective in coordinating a hard cation; the only other structure of an amide featuring a third-period donor and η 2 coordination is that of [Li 2 (PhN−PPh 2 ) 2 (OEt 2 ) 2 ] ( 13 ) with a Li−P distance of 2.684(3) Å.…”

“…Such coordination has been observed in [Li 2 ((CH 3 ) 3 Si-N-N(Si(CH 3 ) 3 )) 2 ] (7), 34 [Li 2 ((CH 3 ) 2 ((CH 3 ) 3 C)Si-N-N(H)Si(C(CH 3 ) 3 )(CH 3 ) 2 ) 2 -(THF) 2 ] (8), 35 [Li 2 ((CH 3 ) 3 Si-N-N(H)C(CH 3 ) 3 ) 2 (THF) 2 ] (9), 35 [Li 2 ((CH 3 ) 3 Si-N-N(CH 2 C 6 H 5 )Si(CH 3 ) 3 ) 2 ] (10), 20 [Li 2 -(C 6 H 5 -N-N(H)Si(CH 3 ) 3 ) 2 (Et 2 O) 2 )] (11), 20 and [Li 2 (F-((CH 3 ) 3 C) 2 Si-N-N(CH 3 ) 2 ) 2 (THF) 2 ] (12). 36 Softer X atoms are less effective in coordinating a hard cation; the only other structure of an amide featuring a third-period donor and η 2 coordination is that of [Li 2 (PhN-PPh 2 ) 2 (OEt 2 ) 2 ] (13) 37 with a Li-P distance of 2.684(3) Å.…”