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Synthesis, Crystal and Molecular Structure of a Twelve‐membered N , N ′‐Di‐lithium‐cyclosiloxazane [Me 2 SiOSiMe 2 N(Li)SiMe 2 O] 2
Author(s) -
Veith Michael,
Rammo Andreas,
Heim Ralf,
Huch Volker
Publication year - 2010
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200900366
Subject(s) - chemistry , crystallography , lithium (medication) , square pyramid , benzene , yield (engineering) , ring (chemistry) , toluene , stereochemistry , crystal structure , materials science , organic chemistry , medicine , metallurgy , endocrinology
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.