TY - JOUR
T1 - Adding rubidium and cesium to the homologous series of alkali metal compounds of (Trimethylsilyl)methanides and 2,2,6,6-Tetramethylpiperidides
AU - Clegg, William
AU - Klett, Jan
AU - Mulvey, Robert E.
AU - Russo, Luca
AU - Kennedy, Alan
PY - 2012/6
Y1 - 2012/6
N2 - (Trimethylsilyl)methylrubidium [RbCH2SiMe3] (1) and (trimethylsilyl)methylcesium [CsCH2SiMe3] (2) were prepared by metathesis reactions of (trimethylsilyl)methyllithium [LiCH2SiMe3] with rubidium or cesium tert-butoxide in n-hexane. Both new compounds are pyrophoric powders which were characterised by NMR spectroscopy and elemental analyses. They can be used as deprotonating agents towards secondary amines such as 2,2,6,6-tetramethylpiperidine (TMPH). The resulting amides [RbTMP] (3) and [CsTMP] (4) form temperature-sensitive, n-hexane-insoluble orange solids. Treatment with the bidentate donor N,N,N',N'-tetramethylethylenediamine (TMEDA) produces the corresponding n-hexane-soluble complexes. The crystal structures of [(TMEDA)RbTMP] (3a) and [(TMEDA)CsTMP] (4a) were determined to be closely related to that of [(TMEDA)KTMP]. Thus they are dimers with frameworks that consist of four-membered MNMN rings (M = Rb, Cs or K, N = TMP). The versatility and stability observed should make these (trimethylsilyl)methyl and TMP compounds of rubidium (1, 3a) and cesium (2, 4a) valuable starting points for further exploration of the chemistry of these heavy alkali metals.
AB - (Trimethylsilyl)methylrubidium [RbCH2SiMe3] (1) and (trimethylsilyl)methylcesium [CsCH2SiMe3] (2) were prepared by metathesis reactions of (trimethylsilyl)methyllithium [LiCH2SiMe3] with rubidium or cesium tert-butoxide in n-hexane. Both new compounds are pyrophoric powders which were characterised by NMR spectroscopy and elemental analyses. They can be used as deprotonating agents towards secondary amines such as 2,2,6,6-tetramethylpiperidine (TMPH). The resulting amides [RbTMP] (3) and [CsTMP] (4) form temperature-sensitive, n-hexane-insoluble orange solids. Treatment with the bidentate donor N,N,N',N'-tetramethylethylenediamine (TMEDA) produces the corresponding n-hexane-soluble complexes. The crystal structures of [(TMEDA)RbTMP] (3a) and [(TMEDA)CsTMP] (4a) were determined to be closely related to that of [(TMEDA)KTMP]. Thus they are dimers with frameworks that consist of four-membered MNMN rings (M = Rb, Cs or K, N = TMP). The versatility and stability observed should make these (trimethylsilyl)methyl and TMP compounds of rubidium (1, 3a) and cesium (2, 4a) valuable starting points for further exploration of the chemistry of these heavy alkali metals.
KW - alkali metals
KW - N-donor ligands
KW - metalation
KW - cesium
KW - carbanions
KW - rubidium
UR - http://www.scopus.com/inward/record.url?scp=84862164336&partnerID=8YFLogxK
U2 - 10.1002/ejic.201200122
DO - 10.1002/ejic.201200122
M3 - Article
VL - 2012
SP - 2989
EP - 2994
JO - European Journal of Inorganic Chemistry
JF - European Journal of Inorganic Chemistry
SN - 1434-1948
IS - 18
ER -