The titanium tert-butyl imido compounds
[Ti(NBu
t
)Cl
2
(NC
5
H
4
R-4)
n
] (R = H, n = 2 or 3;
R = Bu
t
, n = 2) have been
found to be entry points to the half-sandwich
η
5
-cyclopentadienyl derivatives
[Ti(η
5
-C
5
R′
4
R″)(NBu
t
)Cl(NC
5
H
4
R-4)]
(R = Bu
t
,
R′ = R″ = H or Me;
R = H, R′ = H,
R″ = H, Me or Pr
i
; R = H,
R′ = Me, R″ = Me, Et or
C
4
H
7
), the η
5
-1,2,3-trimethylindenyl
species
[Ti(η
5
-C
9
H
4
Me
3
)(NBu
t
)Cl(NC
5
H
4
Bu
t
-4)] and the
bis(η
5
-cyclopentadienyl) compound
[Ti(η
5
-C
5
H
5
)
2
(NBu
t
)(NC
5
H
5
)], the crystal structure of which has
been determined. The complex
[Ti(η
5
-C
5
H
5
)(NBu
t
)Cl(NC
5
H
5
)] readily loses pyridine under vacuum in the
solid state to form the binuclear complex
[Ti
2
(η
5
-C
5
H
5
)
2
(
µ-NBu
t
)
2
Cl
2
]. Treatment of
[Ti(η
5
-C
5
Me
4
R)(NBu
t
)Cl(NC
5
H
5
)] (R = Me or Et) with
Na[C
5
H
5
] gives the corresponding mixed-ring sandwich
derivatives
[Ti(η
5
-C
5
H
5
)(η
5
-C
5
Me
4
R)(NBu
t
)Cl(NC
5
H
5
)]. Addition of Li[C
9
H
7
] to
[Ti(η
5
-C
5
H
5
)(NBu
t
)Cl(NC
5
H
5
)] gave the η
5
-cyclopentadienyl,
η
3
-indenyl mixed-ring analogue
[Ti(η
5
-C
5
H
5
)(η
3
-C
9
H
7
)(NBu
t
)(NC
5
H
5
)].
The complex
[Ti(η
5
-C
5
H
5
)
2
(NBu
t
)(NC
5
H
5
)] undergoes a room-temperature
cyclopentadienyl ligand-redistribution reaction with
[Ti(NBu
t
)Cl
2
(NC
5
H
5
)
2
] forming
[Ti(η
5
-C
5
H
5
)(NBu
t
)Cl(NC
5
H
5
)] in quantitative yield. Variable-temperature NMR
spectra for the half-sandwich complexes show that the co-ordinated pyridine
exchanges with free pyridine via an associative mechanism. The
compound
[Ti(η
5
-C
5
H
5
)(η
5
-C
5
Me
4
Et)(NBu
t
)(NC
5
H
5
)] is also fluxional and exhibits reversible pyridine dissociation at
higher temperatures and restricted rotation about the Ti–N
(pyridine) bond at lower temperatures.
叔丁基亚
氨基
钛化合物 [Ti(NBu t)Cl 2 (NC 5 H 4 R-4) n ](R = H,n = 2 或 3;
R = Bu t ,n = 2)已被发现是半夹心η 5 -
环戊二烯基衍
生物[Ti(η 5 -C 5 R′ 4 R″)(NBu t )Cl(NC 5 H 4 R-4)] (R = Bu t ,R′ = R″ = H 或 Me ;R = H ,R′ = H ,R″ = H ,Me 或 Pr i ;R=H,R′=Me,R″=Me,Et 或 C 4 H 7)、η 5 -1,2,3-三甲基
茚基化合物[Ti(η 5 -C 9 H 4 Me 3 )(NBu t )Cl(NC 5 H 4 Bu t -4)]和双(η 5 -
环戊二烯基)化合物[Ti(η 5 -C 5 H 5 ) 2 (NBu t )(NC 5 H 5 )],其晶体结构已经确定。复合物 [Ti(η 5 -C 5 H 5 )(NBu t )Cl(NC 5 H 5 )] 在固态真空下很容易失去
吡啶,形成双核复合物 [Ti 2 (η 5 -C 5 H 5 ) 2 ( µ-NBu t ) 2 Cl 2 ]。用 Na[C 5 H 5 ]处理[Ti(η 5 -C 5 Me 4 R)(NBu t )Cl(NC 5 H 5 )] (R = Me 或 Et),可得到相应的混环夹心衍
生物[Ti(η 5 -C 5 H 5 )(η 5 -C 5 Me 4 R)(NBu t )Cl(NC 5 H 5 )]。在[Ti(η 5 -C 5 H 5 )(NBu t )Cl(NC 5 H 5 )] 中加入 Li[C 9 H 7 ],可得到 η 5 -
环戊二烯基、η 3 -
茚基混合环类似物[Ti(η 5 -C 5 H 5 )(η 3 -C 9 H 7 )(NBu t )(NC 5 H 5 )]。
复合物 [Ti(η 5 -C 5 H 5 ) 2 (NBu t )(NC 5 H 5 )] 与 [Ti(NBu t )Cl 2 (NC 5 H 5 ) 2 ] 发生室温
环戊二烯配体再分布反应,形成 [Ti(η 5 -C 5 H 5 )(NBu t )Cl(NC 5 H 5 )] 复合物,产量定量。半夹心复合物的变温核磁共振光谱显示,配位
吡啶与游离
吡啶通过缔合机制发生交换。化合物[Ti(η 5 -C 5 H 5 )(η 5 -C 5 Me 4 Et)(NBu t )(NC 5 H 5 )]也具有通性,在较高温度下表现出可逆的
吡啶解离,在较低温度下表现出围绕 Ti-N (
吡啶)键的受限旋转。