Preparation of trimetallic alkoxide complexes exploiting the isomorphous substitution approach. Synthesis, X-ray single crystal and mass-spectrometric study of NbTa(OMe)(8)(ReO4)(2) and Nb2Ta2O2(OMe)(14)(ReO4)(2)

摘要

Alkoxylation of the rhenium heptoxide, Re2O7, with the bimetallic niobium-tantalum methoxide, NbTa(OMe)(10), provided, dependent on the reaction conditions, either (Nb,Ta)(2)(OMe)(8)(ReO4)(2) (1) or (Nb,Ta)(4)O-2(OMe)(14)(ReO4)(2) (II). Niobium and tantalum are distributed very uniformly between the correspondent positions in the molecular structure of I (only one symmetry independent position present for M-v atoms). In the structure of II, the metal atom position connected to the perrhenate ligand has higher niobium content, while that connected to alkoxide groups and the oxoligand has higher tantalum content. Possible reasons for this difference and its influence on the decomposition behavior of I and II on vacuum sublimation are discussed. (C) 2002 Elsevier Science Ltd. All rights reserved. [References: 10]