Rudolph Wolfram W, Irmer Gert
Medizinische Fakultät der TU Dresden, Institut für Virologie im MTZ, Fiedlerstr. 42, 01307 Dresden, Germany.
Technische Universität Bergakademie Freiberg, Institut für Theoretische Physik, Leipziger Str. 23, 09596 Freiberg, Germany.
Dalton Trans. 2017 Mar 27;46(13):4235-4244. doi: 10.1039/c7dt00008a.
Raman spectra of aqueous La, Ce, Pr, Nd and Sm - perchlorate solutions were measured and weak strongly polarized Raman bands were detected at 343 cm, 344 cm, 347 cm, 352 cm and 363 cm, respectively. The full width at half height for these bands is quite broad (∼50 cm) in the isotropic spectrum and the band width increases with increasing solute concentration. The polarized Raman bands were assigned to the breathing modes of the nona-aqua ions of the mentioned rare earth ions. Published structural results confirmed that these ions exist as nona-hydrates in aqueous solutions [Ln(HO)]. The Ln-O bond distances of these rare earth ions correlate well with the band positions of the nona-aqua ions [Ln(OH)] (Ln = La, Ce, Pr, Nd and Sm) and the force constants were calculated for these breathing modes. The strength of the force constants increase with decreasing the Ln-O bond distances (La-O > Ce-O > Pr-O > Nd-O > Sm-O). While the fully hydrated ions are stable in dilute perchlorate solutions (∼0.2 mol L), in concentrated perchlorate solutions outer-sphere ion pairs and contact ion pairs are formed (C > 1.5 mol L). In a hydrate melt at 161 °C of Ce(ClO) plus 6HO, the contact ion pairs are the dominate species. The Raman bands of the ligated perchlorate and the Ce-O breathing mode of the partially hydrated ion pair at 326 cm were measured and characterized. In cerium chloride solutions chloro-complex formation was detected over the measured concentration range from 0.270-2.167 mol L. The chloro-complexes in CeCl(aq) are weak and diminish rapidly with dilution and disappear at a concentration <0.1 mol L. In a CeCl solution, with additional HCl, a series of chloro-complex species of the type [Ce(OH)Cl] (n = 1, 2) were detected.
测量了镧、铈、镨、钕和钐的高氯酸盐水溶液的拉曼光谱，分别在343厘米、344厘米、347厘米、352厘米和363厘米处检测到了弱的强偏振拉曼带。在各向同性光谱中，这些谱带的半高宽相当宽（约50厘米），并且带宽随着溶质浓度的增加而增大。这些偏振拉曼带被归属于上述稀土离子的九水合离子的呼吸模式。已发表的结构结果证实这些离子在水溶液中以九水合物[Ln(H₂O)₉]ⁿ⁺的形式存在。这些稀土离子的Ln - O键长与九水合离子[Ln(OH₂)₉]ⁿ⁺（Ln = La、Ce、Pr、Nd和Sm）的谱带位置有很好的相关性，并且计算了这些呼吸模式的力常数。力常数的强度随着Ln - O键长的减小而增加（La - O > Ce - O > Pr - O > Nd - O > Sm - O）。虽然完全水合的离子在稀高氯酸盐溶液（约0.2摩尔/升）中是稳定的，但在浓高氯酸盐溶液中会形成外层离子对和接触离子对（C > 1.5摩尔/升）。在161℃的Ce(ClO₄)₃加6H₂O的水合物熔体中，接触离子对是主要物种。测量并表征了配位高氯酸盐的拉曼带以及部分水合离子对在326厘米处的Ce - O呼吸模式。在氯化铈溶液中，在0.270 - 2.167摩尔/升的测量浓度范围内检测到了氯配合物的形成。CeCl₃(aq)中的氯配合物很弱，随着稀释迅速减少，在浓度小于＜0.1摩尔/升时消失。在CeCl₃溶液中，加入额外的HCl后，检测到了一系列[Ce(OH)ₙCl₃₋ₙ]（n = 1, 2）类型的氯配合物物种。
