王美玲　臧晴　鐘國(guó)清

摘要在甲醇溶液中，以乙酸鈷、氯化鈷、硝酸鈷和縮二脲為原料合成了3種結(jié)構(gòu)不同的縮二脲鈷配合物.通過元素分析、紅外光譜、X射線粉末衍射和熱分析對(duì)產(chǎn)物進(jìn)行了表征，其化學(xué)組成為[Co（bi）2（H2O）2]（Ac）2·H2O （1），[Co（bi）2Cl2] （2）和[Co（bi）3]（NO3）2·2.5H2O （3） （bi = NH2CONHCONH2）.配合物1中每個(gè)Co2+與2個(gè)縮二脲分子中的4個(gè)羰基氧原子和2個(gè)水分子中的氧原子配位，配合物2中每個(gè)Co2+與2個(gè)縮二脲分子中的4個(gè)羰基氧原子和2個(gè)氯原子配位，而配合物3中每個(gè)Co2+與6個(gè)全部來自縮二脲分子的羰基氧原子配位，均形成了配位數(shù)為6的配合物.配合物1和3的熱分解過程包括失水和配體的分解，而配合物2的熱分解過程只是配體的分解過程，最后完全分解形成氧化鈷.

關(guān)鍵詞縮二脲；鈷配合物；表征；熱分解

Biuret is a kind of important chelating ligand， and can act as an O，O′bidentate neutral ligand or N，N′bidentate anionic ligand binding to metal ions， such as scandium（Ⅲ）[1]， copper（Ⅱ）[2]， samarium（Ⅲ）[3]， thorium（IV）[4] and so on. In recent years the chemistry of biuret and related compounds attracts increasing attention. A novel biscyclometalated complex named [Ir2（mbiuretato N，N′：O，O′）（ptpy）4] was obtained and studied[5]. Whats more， a research in thermal degradation kinetics of biuretformaldehyde polymeric ligand was done lately[6]. In animal husbandry， biuret is an excellent feed additive for ruminants， it has the advantages of good palatability， low toxicity and easy to digest， and is safer than other non protein nitrogen feed additives， such as urea. In medicine， biuret can be used for the preparation of hypnotics and sedatives and it is also good at lowering the blood pressure. In chemical industry， biuret can be utilized as raw materials for synthesis of paints， lubricants， and coatings. At home， the complexes of biuret ligand have been rarely reported[79]， especially in the comparison of different anions in the synthesis of Co（Ⅱ） complexes. The biuret complexes of trace elements as feed additives for ruminants can play a dual role of essential trace elements and non protein nitrogen nutrition supplements. Here we report three Co（Ⅱ） complexes synthesized with biuret and three different cobalt salts.

1Experimental

1.1Materials and physical measurements

All chemicals purchased were of analytical reagent grade and used without further purification. Cobalt acetate tetrahydrate， cobalt chloride hexahydrate， cobalt nitrate hexahydrate and biuret were purchased from Sinopharm Chemical Reagent Co. Ltd. of Shanghai.

Elemental analyses for C， H and N in the complexes were measured on a Vario EL CUBE elemental analyzer， and the content of cobalt was determined by EDTA complexometric titration with murexide as indicator. IR spectra were obtained with KBr pellets on a Nicolet 5700 FTIR spectrophotometer in the range of 4 000～200 cm-1. The powder Xray diffraction measurements were recorded on a D/maxⅡ Xray diffractometer in the diffraction angle range of 3～80°. The thermogravimetric analysis data were obtained using a SDT Q600 thermogravimetry analyzer in the air atmosphere in the temperature range of 20～800 ℃ with a heating rate of 10 ℃ min-1.