Tris(<i>tert</i>-butoxy)siloxy Derivatives of Boron, Including the Boronous
Acid HOB[OSi(O<i><sup>t</sup></i><sup></sup>Bu)<sub>3</sub>]<sub>2</sub> and the Metal (Siloxy)boryloxide Complex
Cp<sub>2</sub>Zr(Me)OB[OSi(O<i><sup>t</sup></i><sup></sup>Bu)<sub>3</sub>]<sub>2</sub>: A Remarkable Crystal Structure with 18
Independent Molecules in Its Asymmetric Unit
Kyle L. Fujdala
Allen G. Oliver
Frederick J. Hollander
T. Don Tilley
10.1021/ic0205482.s001
https://acs.figshare.com/articles/dataset/Tris_i_tert_i_-butoxy_siloxy_Derivatives_of_Boron_Including_the_Boronous_Acid_HOB_OSi_O_i_sup_t_sup_i_sup_sup_Bu_sub_3_sub_sub_2_sub_and_the_Metal_Siloxy_boryloxide_Complex_Cp_sub_2_sub_Zr_Me_OB_OSi_O_i_sup_t_sup_i_sup_sup_Bu_sub_3_sub_sub_2_sub_A_Remarka/3606636
Silanolysis of B(O<i><sup>t</sup></i><sup></sup>Bu)<sub>3</sub> with 2 and 3 equiv of HOSi(O<i><sup>t</sup></i><sup></sup>Bu)<sub>3</sub> led to the formation of <i><sup>t</sup></i><sup></sup>BuOB[OSi(O<i><sup>t</sup></i><sup></sup>Bu)<sub>3</sub>]<sub>2</sub> (<b>1</b>) and
B[OSi(O<i><sup>t</sup></i><sup></sup>Bu)<sub>3</sub>]<sub>3</sub> (<b>2</b>), respectively. Compounds <b>1</b> and <b>2</b> are efficient single-source molecular precursors to B/Si/O
materials via thermolytic routes in nonpolar media, as demonstrated by the generation of BO<sub>1.5</sub>·2SiO<sub>2</sub> (<b>BOSi2</b><b><sub>xg</sub></b>)
and BO<sub>1.5</sub>·3SiO<sub>2</sub> (<b>BOSi3</b><b><sub>xg</sub></b><b>)</b> xerogels, respectively. Use of a block copolymer template provided B/Si/O materials
(<b>BOSi2</b><b><sub>epe</sub></b> and <b>BOSi3</b><b><sub>epe</sub></b>) with a broad distribution of mesopores (by N<sub>2</sub> porosimetry) and smaller, more uniform
particle sizes (by TEM) as compared to the nontemplated materials. Hydrolyses of <b>1</b> and <b>2</b> with excess H<sub>2</sub>O
resulted in formation of the expected amounts of <i><sup>t</sup></i><sup></sup>BuOH and HOSi(O<i><sup>t</sup></i><sup></sup>Bu)<sub>3</sub>; however, reaction of <b>1</b> with 1 equiv of
H<sub>2</sub>O led to isolation of the new boronous acid HOB[OSi(O<i><sup>t</sup></i><sup></sup>Bu)<sub>3</sub>]<sub>2</sub> (<b>3</b>). This ligand precursor is well suited for the
synthesis of new metal (siloxy)boryloxide complexes via proton-transfer reactions involving the BOH group. The
reaction of <b>3</b> with Cp<sub>2</sub>ZrMe<sub>2</sub> resulted in formation of Cp<sub>2</sub>Zr(Me)OB[OSi(O<i><sup>t</sup></i><sup></sup>Bu)<sub>3</sub>]<sub>2</sub> (<b>4</b>) in high yield. This rare example
of a transition metal boryloxide complex crystallizes in the triclinic space group <i>P</i>1̄ and exhibits a crystal structure
with an unprecedented number of independent molecules in its asymmetric unit (i.e., <i>Z</i>‘ = 18 and <i>Z</i> = 36). This
unusual crystal structure presented an opportunity to perform statistical analyses of the metric parameters for the
18 crystallographically independent molecules. Complex <b>4</b> readily converts to Cp<sub>2</sub>Zr[OSi(O<i><sup>t</sup></i><sup></sup>Bu)<sub>3</sub>]<sub>2</sub> (<b>5</b>) upon thermolysis
or upon dissolution in Et<sub>2</sub>O at room temperature.
2003-01-24 00:00:00
N 2 porosimetry
BOH
Bu
BOSi 3 epe
BOSi 2 epe
Et 2 O
TEM
Remarkable Crystal Structure
H 2 O
BOSi 3 xg
uniform particle sizes
block copolymer template
crystal structure
18 Independent Molecules
transition metal boryloxide
Asymmetric Unit Silanolysis
Cp 2 ZrMe 2
BOSi 2 xg
HOB