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Date: 1-1-2017
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Date: 5-3-2019
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Date: 30-4-2019
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Non-aqueous coordination chemistry
A growing number of complexes (generally air- and moisture- sensitive) involving alkali metal ions with O- or Ndonor ligands and formed in non-aqueous media are now known, although the chemistry of the later group 1 metals is not so widely developed as that of Li. A general method of synthesis is to prepare an alkali metal salt in the presence of a coordinating ligand. For example, in [{LiCl(HMPA)}4], use of the bulky ligand HMPA (hexamethylphosphoramide), 10.5, results in the isolation of a discrete complex rather than an extended LiCl lattice; the complex contains the cubic Li4Cl4 core. Increasing the size of the halogen tends to reduce the nuclearity of the product, e.g. [Li2Br2(HMPA)3]. The bonding in these complexes is of interest can be viewed in terms of a central aggregate of Li+ and Cl- ions, and in general, the bonding should be considered to be predominantly ionic.
Amidolithium complexes of type RR’NLi (e.g. R and R’ = alkyl, aryl, silyl) exhibit a fascinating structural diversity; as above, bulky amido ligands are essential for complex stabilization. Planar Li2N2-rings are common structural units, and these appear in a variety of laddered structures which may be polymeric or discrete molecular as in [{tBuHNLi}8] (Figure 1.1).
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دراسة: عدم ترتيب الغرفة قد يدل على مشاكل نفسية
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علماء: تغير المناخ تسبب في ارتفاع الحرارة خلال موسم الحج
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ضمن مؤتمر الإمام الباقر (عليه السلام).. أكاديمي يناقش التربية العقدية في سلوك الآل المحمدي
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