Résumé
The imidotitanium alkyl cations [Ti(N
t
Bu)(Me
3
[9]aneN
3
)R]
+
(R = Me (
3
+
) or CH
2
SiMe
3
(
4
+
)) possess either a very weak α-agostic or β-Si-C agostic interactions, respectively, according to
13
C and
29
Si NMR and DFT studies; reaction of
4
+
with
i
PrNCN
i
Pr gives totally selective insertion into the Ti-alkyl bond; reaction of
3
+
with AlMe
3
gives the first structurally characterised AlMe
3
adduct of a transition metal alkyl cation (Me
3
[9]aneN
3
= 1,4,7-trimethyltriazacyclononane).
The agostic interactions in the imidotitanium alkyl cations [Ti(N
t
Bu)(Me
3
[9]aneN
3
)R]
+
(R = Me or CH
2
SiMe
3
) are described, together with the first experimental probe of M&z.dbd;NR
vs.
M-R site-selectivity in catalytically relevant systems.