The twelve membered and eighteen membered cyclosiloxazanes [Me
2
SiOSiMe
2
N(H)SiMe
2
O]
2
(
3
) and [Me
2
SiOSiMe
2
N(H)SiMe
2
O]
3
(
4
) have been obtained as colourless liquids from the reaction of 1,5-Dichlorohexamethyltrisiloxane with ammonia at-50 °C without any solvent. For compound
3
and
4
, the yield is 30 % and 43 %, respectively. The treatment of
3
with two equivalents of
n
-butyllithium in n-hexane leads in almost quantitative yield (93 %) to the dilithiumsilylamide [Me
2
SiOSiMe
2
N(Li)SiMe
2
O]
2
(
5
). Compound
5
can be isolated at room temperature and recrystallized from benzene without any decomposition or contraction of the ring size. An X-ray structure determination on [Me
2
SiOSiMe
2
N(Li)SiMe
2
O]
2
(
5
) reveals a waved crown-like twelve membered Si
6
N
2
O
4
-cycle. Each of the two lithium ions is coordinated by two nitrogen and two oxygen atoms leading to a square pyramid, in which the metal occupies the apex. The two square-pyramidal coordination figures are located above and below the waved crown-like Si
6
N
2
O
4
-ring sharing a common edge by the atoms N(1) and N(2). All synthesised compounds have been characterised by spectroscopic methods. Because of the lower solubility of the dilithiumsilylamide
5
, only a
1
H-NMR could be applied for further characterisation in solution.