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