Novel tris[2-substituted imidazol-4(5)-yl]phosphane (4-TIPR) ligands 2b (R = Ph) and 2c (R = tBu) were prepared as model ligands for the tris(histidine) motif found in many zinc enzymes. They readily form cobalt and zinc nitrato and chloro complexes in protic solvents. The steric requirements of the substituents R in 4(5)-position of the 4-TIPR ligands (R = iPr (2a), Ph (2b), tBu (2c)) is discussed on the basis of their UV/VIS spectra. Zinc complexes of 2a and 2c were studied due to their ability to promote the hydrolysis of the activated ester 4-nitrophenyl pyridine-2-carboxylate (pNpic).
小说中的三[2-取代
咪唑-4(5)-基]膦(4-TIP
R)
配体2b (R = Ph)和2c (R = tBu)被制备为许多
锌酶中发现的三(组
氨酸)基序的模型
配体。它们在质子溶剂中很容易形成
钴和
锌的
硝酸盐和
氯配合物。基于它们的UV/VIS光谱,讨论了4-TIP
R配体中4(5)-位取代基R的立体位阻要求(iPr (
2a),Ph (
2b),tBu (
2c))。由于它们促进活化酯4-硝基
苯基吡啶-2-羧酸酯(pNpic)的
水解能力,因此研究了2a和2c的
锌配合物。