Series of Comparable Dinuclear Group 4 Neo-pentoxide Precursors for Production of pH Dependent Group 4 Nanoceramic Morphologies

Abstract

A series of similarly structured Group 4 alkoxides was used to explore the cation effect on the final ceramic nanomaterials generated under different pH solvothermal (SOLVO) conditions. The synthesis of [Ti(μ-ONep)(ONep)(3)](2) (1, ONep = OCH(2)C(CH(3))(3)) and {[H][(μ-ONep)(3)M(2)(ONep)(5)(OBu(t))]} where M = Zr (2) and Hf (3, OBu(t) = OC(CH(3))(3)) were realized from the reaction of M(OBu(t))(4) (M = Ti, Zr, Hf) and H-ONep. Crystallization of 1 from py led to the isolation of [Ti(μ-ONep)(ONep)(3)](2)(μ-py) (1a) whereas the dissolution of 2 or 3 in py yielded {(μ(3)-O)(μ(3)-OBu(t))[(μ-ONep)M(ONep)(2)](3)} M = Zr (2a) and Hf (3a). The structurally similar congener set of 1-3 was used to investigate variations of their resultant nanomaterials under solvothermal conditions at high (10 M KOH), low (conc. (aq) HI), and neutral (H(2)O) pH conditions. Reproducible nanodots, -squares, and -rods of varied aspect ratios were isolated based on cation and the reaction pH. The hydrolysis products were reasoned to be the "seed" nucleation sites in these processes, and studying the hydrolysis behavior of 1-3 led to the identification of [Ti(6)(μ(3)-O)(7)(μ-O)(μ-ONep)(2)(ONep)(6)](2) (1b) for 1 but yielded 2a and 3a for 2 and 3, respectively. A correlation was found to exist between these products and the final nanomaterials formed for the acidic and neutral processes. The basic route appears to be further influenced by another property, possibly associated with the solubility of the final nanoceramic material.

New coordination features; a bridging pyridine and the forced shortest non-covalent distance between two CO32−species

“…When found bridging two Ag( i ) ions, 31 the pyridine group was described as “weakly coordinating”, with Ag–N of 2.71 Å. The complex involving Ti( iv ), 32 is the only reported example where the bridging pyridine has been crystallographically solved as disordered over two equivalent positions, showing two distinctly different (2.532 Å and 3.093 Å) Ti–N distances, as found here in complex 1 . In fact, the original solution for the structure of 1 featured a symmetric μ-pyridine ligand.…”

Synthesis, X-ray structures, and characterization of hexafluoro-iso-propoxide group 3 and lanthanide precursors

“…For the Ln (including Y and Sc) compounds reported with a "(OR)3Ln(H2O)" moiety, the Ln-OH2 distances ranged from 2.12 to 2.85 Å. [36] All of the distances noted for the Ln-hfip species in this work, fall at the short end of the literature data. In addition, as can be observed in A variety of solvents (THF-d8, py-d5, CDCl3, D2O) were investigated for analysis of the solution behavior of these compounds.…”

Heterometallic transition metal clusters and cluster-supported coordination polymers derived from Tp- and Tp*-based Mo(W) sulfido precursors

“…Each N atom from bipy was found to bridge two Cu atoms from the same cluster core. This bipy is therefore coordinated in a 4 -N fashion with four Cu atoms from the two cluster cores, which is, to our knowledge, unprecedented for bipy, though the N atoms from some other pyridine derivatives are occasionally found in a 2 -N coordination mode [93][94][95]. The formation of such a rare coordination mode is probably due to the association of the two CN bridges with the two Cu centers in the butterfly-shaped [Tp*WS 3 Cu 2 ] core which sterically 'squeezes' the bipy ligand to form such a 4 -coordination with the Cu-N bond distances of 2.416(6)Å and 2.574(6)Å, respectively.…”