Syntheses and Crystal Structures of Novel Functionalized Lithium Silylamides R (4– n ) Si(N(Li)CH 2 CH 2 NR' 2 ) n (R = Me, Ph, R' = Me, i Pr; n = 2, 3)

The difunctional aminosilanes Ph 2 Si(NHCH 2 CH 2 NMe 2 ) 2 ( 1 ), Me 2 Si(NHCH 2 CH 2 N i Pr 2 ) 2 ( 2 ) and Ph 2 Si(NHCH 2 CH 2 N i Pr 2 ) 2 ( 3 ) were prepared by aminolysis of the chlorosilanes R 2 SiCl 2 (R = Ph, Me) and the corresponding ethylenediamine derivatives H 2 NCH 2 CH 2 NR' 2 (R' = Me, i Pr). The trifunctional aminosilane MeSi(NHCH 2 CH 2 N i Pr 2 ) 3 ( 4 ) was synthesized from MeSiCl 3 and H 2 NCH 2 CH 2 N i Pr 2 in the presence of triethylamine as auxiliary base. Compounds 1–4 were obtained as pale yellow viscous oils that have been characterized by 1 H, 13 C and 29 Si NMR spectroscopy. Treatment of the aminosilanes 1–3 with two equivalents and 4 with three equivalents of n BuLi in hexane led to the corresponding lithium salts, which were recrystallized from n ‐hexane at –25 °C. The crystal structure analysis of Ph 2 Si(N(Li)CH 2 CH 2 NMe 2 ) 2 ( 5 ) and Me 2 Si(N(Li)CH 2 CH 2 N i Pr 2 ) 2 ( 6 ) revealed dimeric molecules which contain a central Li 4 N 4 heterocubane core. Additionally, the lithium atoms are coordinated intramolecularly by NR 2 donor groups. For Ph 2 Si(N(Li)CH 2 CH 2 N i Pr 2 ) 2 ( 7 ) dimers with Si 2 N 4 Li 4 adamantane core were observed. MeSi(N(Li)CH 2 CH 2 N i Pr 2 ) 3 ( 8 ) displays dimers with a rhombododecahedral Si 2 N 6 Li 6 core. Like in compounds 5–7 the cluster structure is supported by intramolecular coordination of the N i Pr 2 donor group.