Onoda Akira, Yamada Yusuke, Okamura Taka-Aki, Yamamoto Hitoshi, Ueyama Norikazu
Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 Japan.
Inorg Chem. 2002 Nov 18;41(23):6038-47. doi: 10.1021/ic010570f.
Two new mononuclear Ca(II) complexes with aryl dihydrogen phosphate ligands having two strategically oriented bulky amide groups, 2,6-(Ph3CCONH)2C6H3OPO3H2 (1), including one with a phosphate monoanion, (NMe4)[CaII[O2P(OH)OC6H3-2,6-(NHCOCPh3)2]3(NCMe)3] (3), and one with a phosphate dianion, [CaIIO3POC6H3-2,6-(NHCOCPh3)23(MeOH)2] (4). Both are analogues for the NH...O hydrogen bonds in the active site of Ca(II)-containing phosphotransferase. Crystallographic studies of these Ca(II) complexes revealed that the amide NHs are directed to uncoordinated O atoms of the phosphates, and the IR and 1H NMR spectra indicate that strong NH...O hydrogen bonds are formed only in the phosphate dianion state. The ligand exchange reaction of 3 with a non-hydrogen-bonded phosphate ligand shows that the NH...O hydrogen bonds prevent the Ca-O bond from dissociation. A scatter plot analysis comparing the distance of a Ca-O bond with the Ca-O-P angle, the Fourier density analysis, and DFT calculations reveal that a partial degree of covalency in the Ca-O(phosphate) bonds is present.
两种新的单核钙（II）配合物，其配体为具有两个处于战略导向位置的大体积酰胺基团的芳基磷酸二氢配体，即2,6-(Ph3CCONH)2C6H3OPO3H2（1），其中包括一种含磷酸单阴离子的配合物，(NMe4)[CaII[O2P(OH)OC6H3-2,6-(NHCOCPh3)2]3(NCMe)3]（3），以及一种含磷酸二阴离子的配合物，[CaIIO3POC6H3-2,6-(NHCOCPh3)23(MeOH)2]（4）。两者都是含Ca（II）磷酸转移酶活性位点中NH...O氢键的类似物。这些Ca（II）配合物的晶体学研究表明，酰胺NHs指向磷酸盐的未配位O原子，红外光谱和1H NMR光谱表明，只有在磷酸二阴离子状态下才会形成强NH...O氢键。3与非氢键结合的磷酸配体的配体交换反应表明，NH...O氢键可防止Ca-O键解离。通过比较Ca-O键距离与Ca-O-P角度的散点图分析、傅里叶密度分析和DFT计算表明，Ca-O（磷酸盐）键中存在一定程度的共价性。
