Department of Physical Chemistry, Chemical Faculty, Gdańsk University of Technology, ul. Gabriela Narutowicza 11/12, PL-80-233 Gdańsk, Poland.
Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O. Box 7015, SE-750 07 Uppsala, Sweden.
Inorg Chem. 2020 Jun 15;59(12):8231-8239. doi: 10.1021/acs.inorgchem.0c00594. Epub 2020 May 28.
The strength of hydrogen bonding to and structure of hydrated oxometallate ions in aqueous solution have been studied by double difference infrared (DDIR) spectroscopy and large-angle X-ray scattering (LAXS), respectively. Anions are hydrated by accepting hydrogen bonds from the hydrating water molecules. The oxygen atom of the permanganate and perrhenate ions form weaker and longer hydrogen bonds to water than the hydrogen bonds in bulk water (i.e., they act as structure breakers), while the oxygen atoms of the chromate, dichromate, molybdate, tungstate, and hydrogenvanadate ions form hydrogen bonds stronger than those in bulk water (i.e., they act as structure makers). The oxometallate ions form one hydration shell distinguishable from bulk water as determined by DDIR spectroscopy and LAXS. The hydration of oxoanions results in X-O bond distances ca. 0.02 Å longer than those in unsolvated ions in the solid state not involved in strong bonding to counterions. The oxygens of oxoanions with a central atom from the second and third series in the periodic table and the hydrogenvanadate ion hydrogen bind three hydrating water molecules, while oxygens of oxoanions with a heavier central atom only form hydrogen bonds to two water molecules.
分别采用双差分红外（DDIR）光谱和大角度 X 射线散射（LAXS）研究了水合氧代金属离子在水溶液中的氢键强度和结构。阴离子通过接受水合水分子的氢键而被水合。相比与体相水中的氢键，高锰酸根和高铼酸根离子中的氧原子与水形成的氢键较弱且较长（即它们充当结构破坏者），而铬酸根、重铬酸根、钼酸根、钨酸根和钒酸氢根离子中的氧原子与水形成的氢键比体相水中的氢键更强（即它们充当结构形成者）。通过 DDIR 光谱和 LAXS 确定，氧代金属离子形成了一个可与体相水区分开来的水合壳。与未与抗衡离子形成强键的固态中不参与强键合的无溶剂离子相比，氧代阴离子的水合导致 X-O 键距离约长 0.02 Å。来自元素周期表第二和第三系列的中心原子的氧代阴离子和钒酸氢根离子与三个水合水分子形成氢键，而较重中心原子的氧代阴离子仅与两个水分子形成氢键。
