10.1021/ja052108q.s005
Cristian Saul Campos-Fernández
Cristian Saul
Campos-Fernández
Brandi L. Schottel
Brandi L.
Schottel
Helen T. Chifotides
Helen T.
Chifotides
Jitendra K. Bera
Jitendra K.
Bera
John Bacsa
John
Bacsa
John M. Koomen
John M.
Koomen
David H. Russell
David H.
Russell
Kim R. Dunbar
Kim R.
Dunbar
Anion Template Effect on the Self-Assembly and
Interconversion of Metallacyclophanes
American Chemical Society
2005
Anion Template Effect
BF 4
anion
bptz
SbF 6
Ni
presence
CH 3 CN
Zn
IO
ClO 4
2005-09-21 00:00:00
Dataset
https://acs.figshare.com/articles/dataset/Anion_Template_Effect_on_the_Self_Assembly_and_Interconversion_of_Metallacyclophanes/3266968
Reactions of 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz) with solvated first-row transition metals
M(II) (M(II) = Ni, Zn, Mn, Fe, Cu) have been explored with emphasis on the factors that influence the
identity of the resulting cyclic products for Ni(II) and Zn(II). The relatively small anions, namely [ClO<sub>4</sub>]<sup>-</sup> and
[BF<sub>4</sub>]<sup>-</sup>, lead to the formation of molecular squares [{M<sub>4</sub>(bptz)<sub>4</sub>(CH<sub>3</sub>CN)<sub>8</sub>}⊂X][X]<sub>7</sub>, (M = Zn(II), Ni(II); X =
[BF<sub>4</sub>]<sup>-</sup>, [ClO<sub>4</sub>]<sup>-</sup>), whereas the larger anion [SbF<sub>6</sub>]<sup>-</sup> favors the molecular pentagon [{Ni<sub>5</sub>(bptz)<sub>5</sub>-(CH<sub>3</sub>CN)<sub>10</sub>}⊂SbF<sub>6</sub>][SbF<sub>6</sub>]<sub>9</sub>. The molecular pentagon easily converts to the square in the presence of excess
[BF<sub>4</sub>]<sup>-</sup>, [ClO<sub>4</sub>]<sup>-</sup>, and [I]<sup>-</sup> anions, whereas the Ni(II) square can be partially converted to the less stable
pentagon under more forcing conditions in the presence of excess [SbF<sub>6</sub>]<sup>-</sup> ions. No evidence for the
molecular square being in equilibrium with the pentagon was observed in the ESI-MS spectra of the individual
square and pentagon samples. Anion-exchange reactions of the encapsulated ion in [{Ni<sub>4</sub>(bptz)<sub>4</sub>(CH<sub>3</sub>CN)<sub>8</sub>}⊂ClO<sub>4</sub>][ClO<sub>4</sub>]<sub>7</sub> reveal that a larger anion such as [IO<sub>4</sub>]<sup>-</sup> cannot replace [ClO<sub>4</sub>]<sup>-</sup> inside the cavity, but
that the linear [Br<sub>3</sub>]<sup>-</sup> anion is capable of doing so. ESI-MS studies of the reaction between [Ni(CH<sub>3</sub>CN)<sub>6</sub>][NO<sub>3</sub>]<sub>2</sub> and bptz indicate that the product is trinuclear. Mass spectral studies of the bptz reactions with
Mn(II), Fe(II), and Cu(II), in the presence of [ClO<sub>4</sub>]<sup>-</sup> anions, support the presence of molecular squares.
The formation of the various metallacyclophanes is discussed in light of the factors that influence these
self-assembly reactions, such as choice of metal ion, anion, and solvent.