Bulky cationic β-diketiminate magnesium complexes

Beitrag in einer Fachzeitschrift


Details zur Publikation

Autorinnen und Autoren: Friedrich A, Pahl J, Elsen H, Harder S
Zeitschrift: Dalton Transactions
Jahr der Veröffentlichung: 2019
Band: 48
Heftnummer: 17
Seitenbereich: 5560-5568
ISSN: 1477-9226
eISSN: 1477-9234


Abstract


Cationic β-diketiminate Mg complexes with the bulky
tBu
BDI ligand and the weakly coordinating anion B(C
6
F
5
)
4

-
have been prepared by the reaction of (
tBu
BDI)MgnBu with [Ph
3
C]
+
[B(C
6
F
5
)
4
]
-
;
tBu
BDI = CH[C(tBu)N-Dipp]
2
and Dipp = 2,6-diisopropylphenyl. Their structures are compared to the previously reported cationic (
Me
BDI)Mg
+
complexes;
Me
BDI = CH[C(Me)N-Dipp]
2
. Crystallization of [(
tBu
BDI)Mg]
+
[B(C
6
F
5
)
4
]
-
from chlorobenzene gave a unique (
tBu
BDI)Mg
+
·ClC
6
H
5
cation with a rather short Mg⋯Cl and consequently long C-Cl bond. Crystallization from chlorobenzene/arene solvent mixtures gave (
tBu
BDI)Mg
+
·arene complexes (arene = benzene, toluene, m-xylene) but in the presence of mesitylene the chlorobenzene complex was formed. Due to the greater shielding of the metal, none of these complexes display Mg⋯(F
5
C
6
)
4
B
-
interactions. Crystal structures of the arene complexes show in all cases η
2
-coordination of the arene ligands. Ring slippage from a more favorable η
2
-coordination can be explained by the steric bulk of the
tBu
BDI ligand. The smaller arenes, benzene and toluene, also bind to (
tBu
BDI)Mg
+
in bromobenzene solution. The Lewis acidity of these cationic Mg complexes was determined by the Gutmann-Beckett test. The acceptor number for (
tBu
BDI)Mg
+
(AN = 76.0) is substantially higher than that estimated for (
Me
BDI)Mg
+
(AN = 70.3). Calculation of the atomic NPA charges by DFT shows that the Mg
2+
ion in (
tBu
BDI)Mg
+
is slightly more positively charged than the metal in (
Me
BDI)Mg
+
, confirming its higher Lewis acidity. The lower benzene complexation energy calculated for (
tBu
BDI)Mg
+
versus (
Me
BDI)Mg
+
is due to steric congestion of the metal in the (
tBu
BDI)Mg
+
cation which allows only for Mg⋯(η
1
)C
6
H
6
instead of Mg⋯(η
6
)C
6
H
6
bonding. This ring slippage, however, results in a significant polarization of the electron density in the benzene ring, making it susceptible for nucleophilic attack..


FAU-Autorinnen und Autoren / FAU-Herausgeberinnen und Herausgeber

Elsen, Holger
Lehrstuhl für Anorganische und Metallorganische Chemie
Friedrich, Alexander
Lehrstuhl für Anorganische und Metallorganische Chemie
Harder, Sjoerd Prof. Dr.
Lehrstuhl für Anorganische und Metallorganische Chemie
Pahl, Jürgen
Lehrstuhl für Anorganische und Metallorganische Chemie


Zitierweisen

APA:
Friedrich, A., Pahl, J., Elsen, H., & Harder, S. (2019). Bulky cationic β-diketiminate magnesium complexes. Dalton Transactions, 48(17), 5560-5568. https://dx.doi.org/10.1039/c8dt03576h

MLA:
Friedrich, Alexander, et al. "Bulky cationic β-diketiminate magnesium complexes." Dalton Transactions 48.17 (2019): 5560-5568.

BibTeX: 

Zuletzt aktualisiert 2019-17-05 um 13:08