10.1021/om950537z.s001
Sylviane Isoz
Sylviane
Isoz
Carlo Floriani
Carlo
Floriani
Kurt Schenk
Kurt
Schenk
Angiola Chiesi-Villa
Angiola
Chiesi-Villa
Corrado Rizzoli
Corrado
Rizzoli
Niobium−Carbon Functionalities Supported by
<i>meso</i>-Octaethylporphyrinogen and Derived Macrocycles
American Chemical Society
1996
C 4 H 2 N
macrocyclic ligand
report concerns
Et 8 N 4
SCF
Et 7
insertion reaction
Et 8
ethyl groups
Nb
NMR studies
η 2
1736 cm
Bu t NC
AgSO 3 CF 3
state structures
meso
organometallic chemistry
metal center
Derived Macrocycles
1996-01-09 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Niobium_Carbon_Functionalities_Supported_by_i_meso_i_-Octaethylporphyrinogen_and_Derived_Macrocycles/3776172
This report concerns the organometallic chemistry of niobium based
on a macrocyclic ligand.
To this purpose, the
(<i>meso-</i>octaalkylporphyrinogen)niobium(V) complex
[(η<sup>5</sup>:η<sup>1</sup>:η<sup>5</sup>:η<sup>1</sup>-Et<sub>8</sub>N<sub>4</sub>)NbCl], <b>2</b>, has been used as an appropriate starting material.
The ionization of the Nb−Cl
bond by the use of AgSO<sub>3</sub>CF<sub>3</sub> gave a
bifunctional acid−base system with an increased acidity
of the metal center in
[(η<sup>5</sup>:η<sup>1</sup>:η<sup>1</sup>:η<sup>1</sup>-Et<sub>8</sub>N<sub>4</sub>)Nb(THF)(O<sub>3</sub>SCF<sub>3</sub>)],
<b>3</b>. The alkylation of <b>2</b> with
LiMe
gave a quite stable Nb(V) organometallic derivative
[(η<sup>5</sup>:η<sup>1</sup>:η<sup>1</sup>:η<sup>1</sup>-Et<sub>8</sub>N<sub>4</sub>)Nb−Me],
<b>4</b>, which
undergoes a migratory insertion reaction with Bu<sup>t</sup>NC
leading to an η<sup>2</sup>-iminoacyl derivative
[(η<sup>5</sup>:η<sup>1</sup>:η<sup>1</sup>:η<sup>1</sup>-Et<sub>8</sub>N<sub>4</sub>)Nb(Bu<sup>t</sup>NC)(η<sup>2</sup>-C(Me)NBu<sup>t</sup>)],
<b>6</b> (ν<sub>C</sub><sub></sub><sub>N</sub>, 2217 and
1736 cm<sup>-1</sup>). Two steps
of the reaction have been identified. An attempt to functionalize
the NbO in
[(η<sup>5</sup>:η<sup>1</sup>:η<sup>1</sup>:η<sup>1</sup>-Et<sub>8</sub>(C<sub>4</sub>H<sub>2</sub>N)<sub>3</sub>(<i>p</i>-MeC<sub>5</sub>H<sub>2</sub>N)NbO],
<b>7</b>, by the use of LiMe led, on the contrary, to
[(η<sup>1</sup>:η<sup>1</sup>:η<sup>1</sup>:η<sup>1</sup>-Et<sub>7</sub>(CH-Me)(C<sub>4</sub>H<sub>2</sub>N)<sub>3</sub>(<i>p</i>-MeC<sub>5</sub>H<sub>2</sub>N)NbOLi(THF)<sub>3</sub>],
derived from the metalation of one of the
<i>meso</i>-ethyl groups in <b>9</b>. While X-ray analysis
provided information on the solid state
structures of <b>3</b>, <b>4</b>, <b>6</b>, and
<b>9</b>, NMR studies allowed us to establish a relationship
between the
bonding mode of the porphyrinogen in the solid state and in solution.