We present two important
trends in the reactivity of the titanium
complex [
Me
NacNacTi(Cl){η
2
-P(SiMe
3
)-P
t
Bu
2
}] (
Me
NacNac
–
= [Ar]NC(Me)CHC(Me)N[Ar]; Ar = 2,6-
i
Pr
2
Ph) with nucleophilic reagents RLi (R = Ph
2
P,
t
BuO, (Me
3
Si)
2
N, and
t
Bu
2
N) depending on the reaction medium. Reaction
in nonpolar solvent (toluene) leads to three main products: via an
autoredox process and nucleophilic substitution at the Ti-atom to
afford the Ti(IV) complex [
Me
NacNacTi(R){η
2
-P-P
t
Bu
2
}] (
1
for R = PPh
2
), via the elimination of Me
3
SiR to afford Ti(III)
complex [
Me
NacNacTi(Cl){η
2
-P-P
t
Bu
2
}]
−
[Li(12-crown-4)
2
]
+
(
2
), and via 2e
–
reduction process to afford new ionic complex [{ArNC(Me)CHC(Me)}Ti=NAr{η
1
-P(SiMe
3
)-P
t
Bu
2
}]
−
[Li(12-crown-4)
2
]
+
(
3
). Quite differently, the complex [
Me
NacNacTi(Cl){η
2
-P(SiMe
3
)-P
t
Bu
2
}] reacts
with Ph
2
PLi in THF, unexpectedly yielding two new, four-coordinate
Ti(IV) imido complexes
4a
[{ArNC(Me)=CHC(H)(Me)-P(P
t
Bu
2
)}Ti=NAr(Cl)]
−
[Li(12-crown-4)
2
]
+
·(toluene)
2
and
4b
[{ArNC(CH
2
)CH=C(Me)-P(P
t
Bu
2
)}Ti=NAr(Cl)]
−
[Li(12-crown-4)
2
]
+
·(Et
2
O). Complex
2
dissolved in THF converts to
4a
and
4b
.
1
,
2
,
3
,
4a
, and
4b
were characterized by X-ray diffraction.
1
,
4a
, and
4b
were also fully characterized
by multinuclear NMR spectroscopy.