Hydrogen bonding interactions in phase A [Mg7Si2O8(OH)6] at ambient and high pressure
Hydrogen bonding interactions in phase A [Mg7Si2O8(OH)6] at ambient and high pressure
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环境压力和高压下 A 相 [Mg7Si2O8(OH)6] 中的氢键相互作用
DOI：
10.1007/s002690050251
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发表时间：
2000
影响因子：
1.4
通讯作者：
J. Loveday
中科院分区：
文献类型：
--
作者：
H. Kagi;J. Parise;H. Cho;G. Rossman;J. Loveday
在常压和3.2 GPa（由A相的可压缩性计算）条件下收集了氘化化合物A相（Mg7Si2O8(OH)6）的中子粉末衍射数据，并用Rietveld法对其结构进行了细化。推导出的晶体结构表明，氢原子在A相中占据两个不同的位置，两者都与同一个氧原子形成不同长度的氢键。红外光谱显示出3400和3513 cm−1处对应OH伸缩振动的两个吸收带，质子核磁共振光谱显示出两个强度相等的峰，各向同性化学位移分别为3.7和5ppm。在环境压力下的D-D距离[D(1)-D(2)距离]由中子衍射数据得到为2.09±0.02 Å，由核磁共振谱得到为2.09±0.05 Å。在3.2 GPa时，O-D原子间距离没有统计学意义上的增加，而在环境压力下，其中一个氢位点D(1)的氢键相互作用D···O似乎增加了，与另一个氢位点D(2)相比，D(1)具有更强的氢键相互作用。D(1)和D(2)的O-D键价在环境压力下分别为0.86和0.91，在3.2 GPa下分别为0.83和0.90。
Neutron powder diffraction data of phase A (Mg7Si2O8(OH)6) were collected at ambient pressure and 3.2 GPa (calculated from the compressibility of phase A) from the deuterated compound, and the structure was refined using the Rietveld method. The derived crystal structure implies that hydrogen atoms occupy two distinct sites in phase A, both forming hydrogen bonds of different lengths with the same oxygen atom. This picture is supported by IR spectra, which exhibit two absorption bands at 3400 and 3513 cm−1corresponding to OH stretching vibrations, and proton NMR spectra, which display two peaks with equal intensities and isotropic chemical shifts of 3.7 and 5 ppm. The D-D distance [D(1)-D(2) distance] at ambient pressure was found to be 2.09 ± 0.02 Å from the neutron diffraction data and 2.09 ± 0.05 Å from the NMR spectra. At 3.2 GPa, there is no statistically significant increase in the O-D interatomic distance while the hydrogen bonding interaction D···O appears to increase for one of the hydrogen sites, D(1), which has the stronger hydrogen bonding interaction compared with the other hydrogen, D(2), at ambient pressure. The O-D bond valences, determined indirectly from the D···O distances were 0.86 and 0.91 at ambient pressure, and 0.83 and 0.90 at 3.2 GPa, for D(1) and D(2), respectively.