Reactions of titanocene bis(trimethylsilyl)acetylene complexes with carbodiimides: an experimental and theoretical study of complexation versus C-N bond activation.
The reaction of the low valent metallocene(II) sources Cp'(2)Ti(η(2)-Me(3)SiC(2)SiMe(3)) (Cp' = η(5)-cyclopentadienyl, 1a or η(5)-pentamethylcyclopentadienyl, 1b) with different carbodiimide substrates RN═C═NR' 2-R-R' (R = t-Bu; R' = Et; R = R' = i-Pr; t-Bu; SiMe(3); 2,4,6-Me-C(6)H(2) and 2,6-i-Pr-C(6)H(3)) was investigated to explore the frontiers of ring strained, unusual four-membered heterometallacycles 5-R. The product complexes show dismantlement, isomerization, or C-C coupling of the applied carbodiimide substrates, respectively, to form unusual mono-, di-, and tetranuclear titanium(III) complexes. A detailed theoretical study revealed that the formation of the unusual complexes can be attributed to the biradicaloid nature of the unusual four-membered heterometallacycles 5-R, which presents an intriguing situation of M-C bonding. The combined experimental and theoretical study highlights the delicate interplay of electronic and steric effects in the stabilization of strained four-membered heterometallacycles, accounting for the isolation of the obtained complexes.
Leibniz-Institut für Katalyse e.V. an der Universität Rostock, Albert-Einstein-Strasse 29a, D-18059 Rostock, Germany.
Martin
M
Haehnel
Martin
M
Ruhmann
Oliver
O
Theilmann
Subhendu
S
Roy
Torsten
T
Beweries
Perdita
P
Arndt
Anke
A
Spannenberg
Alexander
A
Villinger
Eluvathingal D
ED
Jemmis
Axel
A
Schulz
Uwe
U
Rosenthal