A series of a
lky
lammonium-imidazo
lium ch
loride sa
lts [RImH(CH
2)
nNMe
2]C
l·HC
l (R = Me,
t-Bu, Mes;
n = 2, 3) have been prepared by a
lky
lation of 1-substituted imidazo
le compounds with the corresponding ch
loro-a
lky
l-dimethy
lamine hydroch
loride. These sa
lts are precursors for the synthesis of a
library of rhodium(I) comp
le
xes containing amino-a
lky
l functiona
lized N-heterocyc
lic carbene (NHC)
ligands with hemi
labi
le character by varying the substituent on the heterocyc
lic ring and the
length of the
linker with the dimethy
lamino moiety. The monodeprotonation of a
lky
lammonium-imidazo
lium sa
lts with NaH in the presence of [{Rh(μ-C
l)(cod)}
2] gave the amino-imidazo
lium sa
lts [RImH(CH
2)
nNMe
2][RhC
l2(cod)]. Further deprotonation with NaH under non anhydrous conditions gave the neutra
l comp
le
xes [RhC
l(cod)(RIm(CH
2)
nNMe
2)] in good yie
lds. The abstraction of the ch
loro
ligand by si
lver sa
lts rendered the cationic comp
le
xes [Rh(cod)(κ
2C,N-RIm(CH
2)
3NMe
2)][BF
4] (R = Me, Mes) by coordination of the NMe
2 fragment of the sidearm of the functiona
lized NHC
ligands. The cata
lytic activity of the rhodium comp
le
xes in the hydrosi
ly
lation of termina
l a
lkynes using HSiMe
2Ph has been investigated with Ph-C
CH,
t-Bu-C
CH,
n-Bu-C
CH, and Et
3Si-C
CH as substrates. Higher activities were achieved using neutra
l comp
le
xes having sma
ll substituents at the heterocyc
lic ring (R = Me). Exce
llent se
lectivities in the β-(
Z)-viny
lsi
lane isomer were found in the hydrosi
ly
lation of 1-hexyne and predominant
ly the β-(
E) and α-bis(si
ly
l)a
lkene isomers were obtained in the hydrosi
ly
lation of triethy
lsi
ly
lacety
lene.