Heteroleptic Complexes of Zirconium Acetylacetonates: Better Precursors for the Preparation of Zirconia. Structural Characterization of [(acac)₂Zr{ONC(Me)py‐2}₂]

Abstract

The reactions of the heteroleptic zirconium diisopropoxide bis(acetylacetonate) in benzene solution with two equivalents of oximes, alkoxyalkanols, triphenylsilanol and trimethylsilyl acetate yield products with the formula [{MeC(O)CHC(O)Me}2ZrL2] with L = —ONC(Me)C5H4N‐2, —ONC(Me)C4H3O‐2, —OCH2CH2OR (R = Me, Et, Bun; py = pyridine, fu = furan), —OSiPh3 and —OSiMe3. Most of these derivatives are solids, but the [(acac)2Zr(OSiMe3)2] is a viscous oil. They could be purified either by recrystallization or by vacuum distillation; all of these are monomeric in boiling benzene. Their elemental analyses, molecular weight measurements and IR as well as NMR spectra were measured. The oximato complex [(acac)2Zr{ONC(Me)py‐2}2] has been shown by single crystal X‐ray crystallography to be monoclinic and mononuclear in the solid state, where zirconium has the coordination number 8; all the ligands are situated in cis‐ position and the oximato ligand binds via N and O in a dihapto (η2‐N, O) manner.

Synthesis and characterization of some oxovanadium(V) complexes with internally functionallized oximes. Crystal and molecular structure of heptacoordinated [VOCl{ON=C(CH3) (C4H3S-2)}2] · CH3OH

“…These show that the vanadium(V) atom is heptacoordinated with distorted pentagonal bipyramidal geometry. The oximato ligands are all bonded in a dihapto (g 2 -N,O) manner with the formation of three-membered rings [45,49]. The dimensions within the two oximato ligands are essentially the same as those found in other coordinated ON=C(CH 3 )(C 4 H 3 S-2) groups, including the closely related compound [VO{ON=C(CH 3 )(C 4 H 3 S-2)} 3 ] AE 0.5C 6 H 6 [49].…”

“…spectra The i.r. spectra of all these complexes (Table 4) were interpreted by comparison with those of the free oximes and other related complexes [26,29,45,58].…”

“…Oximes, including internally functionallized oximes, constitute an important class of N/O type donor ligands [34][35][36][37][38][39] because of their varying coordination abilities with the metal centers. Our previous studies on oximato complexes with some main group and transition metals show quite interesting structural features in both the solution and solid states [40][41][42][43][44][45][46][47]. The distinctive preference of the vanadium ion for these types of ligands has further promoted the synthesis and characterization of many model complexes containing N/O donor ligands [2,3,6,12,25,33,48,49].…”

11 Titanium, zirconium and hafnium

“…Zr is eight co-ordinate in [(acac) 2 Zr{ONC(Me)py-2} 2 ] which has an all-cis structure with a dihapto (g 2 -N,O) oximate ligand. 36 , with an edge-shared bis(tetrahedral) coordination geometry around Ti (Ti-Ti 3.0301 A ˚). The Ti-Ti distance in the compounds [Cp' 2 Ti(m-X) 2 TiCp' 2 ] increases as X is changed from Cl to Br, but remains almost the same in [(ArO) 2 Ti(m-X) 2 Ti(OAr) 2 ] (ArO ~2,6diphenylphenoxide), owing to a titanium-titanium bonding interaction.…”

9 Titanium, zirconium and hafnium

“…Although volatile, most are solids at room temperature, though [(acac) 2 Zr(OSiMe 3 ) 2 ] is a viscous oil. The oximate, all-cis-[(acac) 2 Zr{ONC(Me)(C 5 H 4 N-2)} 2 ], has eight-coordination of zirconium, the oximate ligands binding in a dihapto (g 2 -N,O) manner 25. [Mg 2 (OR) 4 (AlMe 3 ) 2 ] (OR = 1-methoxy-2-propoxide) reacts with ZrCl 4 forming [ZrCl 3 (OR) 2 (AlMe 2 )], which has seven-coordinate Zr 26.…”