Synthesis of compounds with C-P-P and C&z.dbd;P-P bond systems based on the phospha-Wittig reaction
A reactivity study of a β-diketiminate titanium( iii ) phosphanylphosphido complex [ Me NacNacTi(Cl){η 2 -P(SiMe 3 )-P t Bu 2 }] ( 1 ) towards ketones such as benzophenone, 9-fluorenone, acetophenone, cyclopentanone, cyclohexanone and cycloheptanone is reported. The reactions of 1 with aromatic keto...
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Veröffentlicht in: | Dalton transactions : an international journal of inorganic chemistry 2020-10, Vol.49 (39), p.13635-13646 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | A reactivity study of a β-diketiminate titanium(
iii
) phosphanylphosphido complex [
Me
NacNacTi(Cl){η
2
-P(SiMe
3
)-P
t
Bu
2
}] (
1
) towards ketones such as benzophenone, 9-fluorenone, acetophenone, cyclopentanone, cyclohexanone and cycloheptanone is reported. The reactions of
1
with aromatic ketones (without α-protons) directly lead to the Ti(
iii
) complex [
Me
NacNacTi(μ
2
-Cl)(OSiMe
3
)] (
5
) and Ti(
iv
) complexes with the pinacol condensation product [
Me
NacNacTi(OSiMe
3
)(η
2
-pinacolate)] (
3
), and phosphanylphosphaalkenes Ph
2
C&z.dbd;P-P
t
Bu
2
(
2
) and (fluorenyl)C&z.dbd;P-P
t
Bu
2
(
6
), respectively. The reaction with acetophenone leads to the titanium(
iii
) complex with the aldol condensation product as ligand [
Me
NacNacTi(Cl){OC{Me(Ph)}CH
2
(C&z.dbd;O)Ph}] (
8
) and in parallel to phosphanylphosphaalkene (Ph)MeC&z.dbd;P-P
t
Bu
2
(
9
) and
5
. The reactions of
1
with cyclic ketones (cyclopentanone and cyclohexanone) lead to Ti(
iii
) complexes [{(ArN&z.dbd;C(Me)CHC(Me)&z.dbd;NAr)((CH
2
)
4
CO)}Ti(Cl){P
t
Bu
2
-P(SiMe
3
)((CH
2
)
4
CO)}] (
10
) and [{(ArN&z.dbd;C(Me)CHC(Me)&z.dbd;NAr)((CH
2
)
5
CO)}Ti(Cl){P
t
Bu
2
-P(SiMe
3
)((CH
2
)
5
CO)}] (
11
), which are formed
via
the successive insertion of two molecules of ketone to one molecule of
1
. The stability investigation of complexes
10
and
11
in a polar solvent (THF) revealed that under these conditions, the complexes decompose, resulting in titanium(
iii
) complexes with aldol condensation products and the expected phosphanylphosphaalkenes (CH
2
)
4
C&z.dbd;P-P
t
Bu
2
(
10a
) and (CH
2
)
5
C&z.dbd;P-P
t
Bu
2
(
11a
). In the reaction of
1
with cycloheptanone, only the Ti(
iii
) complex with the aldol condensation product [
Me
NacNacTi(Cl){OC(CH
2
)
6
}CH(C&z.dbd;O)(CH
2
)
5
] (
12
) was isolated. The structures
3
,
5
,
8
,
10
,
11
,
11b
and
12
were characterized by X-ray spectroscopy, while all the phosphanylphosphaalkenes were characterized by NMR spectroscopy.
This work presents the reactivity of [
Me
NacNacTi(Cl){η
2
-P(SiMe
3
)-P
t
Bu
2
}] towards ketones such as benzophenone, 9-fluorenone, acetophenone, cyclopentanone, cyclohexanone and cycloheptanone based on the phospha-Wittig reaction. |
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ISSN: | 1477-9226 1477-9234 |
DOI: | 10.1039/d0dt02728f |