Regulation of Metal Complexes by Ligands

配体对金属配合物的调节

基本信息

批准号：
63470041
负责人：
KIDA Shigeo
金额：
$ 4.29万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1990
项目状态：
已结题

项目摘要

There are two factors the stabilization of oxidation state of metal elements ; i. e., l) electronic state of ligand coordinated to the metal, and 2) coordination structure. The purpose of the present study is to stabilize metal oxidation states which are usually unstable by choosing suitable ligands to stabilize such oxidation states.Donor atoms with high electron density generally tends to stabilize a high oxidation state of the central metal. As a suitable ligand of our purpose N-2-hydroxyphenyl) salicylamide and its homologues were adopted in this study. By employing this ligand we have obtained several manganese (IV) and (V) complexes as pure crystals. Further, we have confirmed the formation of copper (III) and cobalt (IV) complexes in solution. Varying the substituents on the ligand, we could see the effect of electron density of the donor atoms on the oxidation states of central metal.It is well-known that cobalt (II) ammine and amine complexes are readily oxidized to cobalt (III) complexes. However, we have found that the oxidation of cobalt (II) complexes with 1, 4, 8, 11-tetrakis (2-aminoethyl)-1, 4, 8, 11-tetraazacyclo-tetradecane (abbreviated as taec) are difficult. This fact has been explained as that in such complexes, because of the steric hindrance of the ligand, cobalt could not take 6-coordination which is the spacifically favored coordination number of cobalt (III). Based on this view, we have synthesized air-stable chromium (II) complexes. Further, this view has been verified by the ready oxidation of Co (II) in the case of Co_2CO_3 (taec) (ClO_4)_2 in which the cobalt is 6-coordinated.

金属元素氧化态的稳定有两个因素；我。 e.，l) 与金属配位的配体的电子态，以及 2) 配位结构。本研究的目的是通过选择合适的配体来稳定通常不稳定的金属氧化态，以稳定这种氧化态。具有高电子密度的供体原子通常倾向于稳定中心金属的高氧化态。本研究采用 N-2-羟基苯基）水杨酰胺及其同系物作为我们目的的合适配体。通过使用该配体，我们获得了几种锰 (IV) 和 (V) 配合物的纯晶体。此外，我们还证实了溶液中铜（III）和钴（IV）络合物的形成。改变配体上的取代基，我们可以看到供体原子的电子密度对中心金属氧化态的影响。众所周知，钴(II)氨和胺配合物很容易被氧化成钴(III)配合物。然而，我们发现钴(II)配合物与1,4,8,11-四(2-氨基乙基)-1,4,8,11-四氮杂环十四烷(缩写为taec)的氧化很困难。这一事实被解释为，在此类配合物中，由于配体的空间位阻，钴不能采取6-配位，而6-配位是钴(III)的空间有利配位数。基于这一观点，我们合成了空气稳定的铬（II）配合物。此外，在钴为6配位的Co_2CO_3(taec)(ClO_4)_2的情况下，Co(II)的容易氧化也证实了这一观点。