|
Compounds of zinc are chemical compounds containing the element zinc which is a member of the group 12 of the periodic table. The oxidation state of most compounds is the group oxidation state of +2. Zinc may be classified as a post-transition main group element with zinc(II) having much chemical behaviour in common with copper(II). Many salts of zinc(II) are isomorphous with salts of magnesium(II) due to the ionic radii of the cations being almost the same. Zinc forms many complexes; metallo-proteins containing zinc are widespread in biological systems. ==General characteristics== Zinc atoms have an electronic configuration of ()3d104s2. When compounds in the +2 oxidation state are formed the ''s'' electrons are lost, so the bare zinc ion has the electronic configuration ()3d10. Examples of these zinc compounds include zinc oxide, ZnO and zinc sulfide, ZnS, (zincblende) in which the oxide and sulfide ions are tetrahedrally bound to four zinc ions. Many complexes, such as ZnCl42−, are tetrahedral. Tetrahedrally coordinated zinc is found in metallo-enzymes such as carbonic anhydrase. However 6-coordinate octahedral complexes can also be found, such as the ion ()2+, which is present when a zinc salt is dissolved in water. Many zinc(II) salts are isomorphous (have the same type of crystal structure) with the corresponding salts of magnesium(II) which results from the fact that Zn2+ and Mg2+ have almost identical ionic radii. This comes about because of the d-block contraction. Whilst calcium is somewhat larger than magnesium, there is a steady decrease in size as atomic number increases from calcium to zinc. It is by chance that the ionic radius of zinc that is almost equal to that of magnesium. In most other respects the chemistry of zinc(II) most closely resembles the chemistry of copper(II), its neighbour in the periodic table, in which there is one less electron. However, whereas Cu2+ is classed as a transition metal ion by virtue of its electronic configuration, ()3d9, in which there is an incomplete ''d''-shell, Zn2+ is best considered to be an ion of a post-transition main group element. The IUPAC periodic table places zinc in the d-block. Some compounds with zinc in the oxidation state +1 are known. The compounds have the formula RZn2R and they contain a Zn — Zn bond analogous to the metal-metal bond in mercury(I) ion, Hg22+. In this respect zinc is similar to magnesium where low-valent compounds containing a Mg — Mg bond have been characterised. No compounds of zinc in oxidation states other than +1 or +2 are known. Calculations indicate that a zinc compound with the oxidation state of +4 is unlikely to exist. Although higher oxidation states are more stable with the heavier elements of a group, the compound was only characterized at 4 K in a neon/argon matrix.〔Xuefang Wang; Lester Andrews; Sebastian Riedel; and Martin Kaupp (2007). "Mercury Is a Transition Metal: The First Experimental Evidence for HgF4.". ''Angew. Chem. Int. Ed.'' 46 (44): 8371–8375. PMID 17899620〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Compounds of zinc」の詳細全文を読む スポンサード リンク
|