Skibsted Jørgen, Jakobsen Hans J.
Instrument Centre for Solid-State NMR Spectroscopy, Department of Chemistry, University of Aarhus, DK-8000 Aarhus C, Denmark.
Inorg Chem. 1999 Apr 19;38(8):1806-1813. doi: 10.1021/ic9811650.
35Cl quadrupole coupling constants (C(Q)), asymmetry parameters (eta(Q)), and isotropic chemical shifts (delta(iso)) have been determined for a series of inorganic perchlorates from (35)Cl magic-angle spinning (MAS) NMR spectra at 14.1 T. Illustrative (37)Cl MAS NMR spectra are obtained and analyzed for some of the samples. For perchlorate anions with quadrupolar couplings less than about 1 MHz, the (35)Cl/(37)Cl NMR parameters are most precisely determined from the full manifold of spinning sidebands observed for the satellite transitions while line-shape analysis of the central transition is employed for the somewhat larger quadrupolar couplings. The environments for the individual perchlorate anions are best characterized by the quadrupole coupling parameters (e.g., C(Q) ranges from 0.3 to 3.0 MHz), while the dispersion in the isotropic (35)Cl chemical shifts is small (1029 ppm < delta(iso) < 1049 ppm) for the perchlorates studied. Due to the variation in quadrupole coupling parameters, (35)Cl MAS NMR may conveniently be employed for identification of anhydrous and hydrated phases of perchlorates, in studies of phase transitions, hydration reactions, and the composition of mixed phases. The perchlorates studied include anhydrous KClO(4), RbClO(4), CsClO(4), (CH(3))(4)NClO(4), and the anhydrous and/or hydrated forms of LiClO(4), NaClO(4), Mg(ClO(4))(2), Ba(ClO(4))(2), and Cd(ClO(4))(2). The (35)Cl MAS NMR spectra of LiClO(4), Mg(ClO(4))(2), and Ba(ClO(4))(2), for which the crystal structures are unknown, reveal that each of these salts possesses a single perchlorate site in the asymmetric unit. The (35)Cl NMR data for Mg(ClO(4))(2) and Ba(ClO(4))(2) suggest that these two samples are isostructural. Relationships between the (35)Cl NMR parameters and crystal symmetries are discussed for the other perchlorates where crystal structure data have been reported.
通过在14.1 T下的³⁵Cl魔角旋转（MAS）核磁共振谱，测定了一系列无机高氯酸盐的³⁵Cl四极耦合常数（C(Q)）、不对称参数（η(Q)）和各向同性化学位移（δ(iso)）。对一些样品获取并分析了示例性的³⁷Cl MAS核磁共振谱。对于四极耦合小于约1 MHz的高氯酸根阴离子，³⁵Cl/³⁷Cl核磁共振参数最精确地由卫星跃迁所观察到的完整旋转边带流形确定，而对于稍大的四极耦合，则采用中心跃迁的线形分析。各个高氯酸根阴离子的环境最好由四极耦合参数来表征（例如，C(Q)范围为0.3至3.0 MHz），而在所研究的高氯酸盐中，各向同性³⁵Cl化学位移的分散很小（1029 ppm < δ(iso) < 1049 ppm）。由于四极耦合参数的变化，³⁵Cl MAS核磁共振可方便地用于鉴定高氯酸盐的无水相和水合相，用于相变、水合反应以及混合相组成的研究。所研究的高氯酸盐包括无水KClO₄、RbClO₄、CsClO₄、(CH₃)₄NClO₄，以及LiClO₄、NaClO₄、Mg(ClO₄)₂、Ba(ClO₄)₂和Cd(ClO₄)₂的无水和/或水合形式。LiClO₄、Mg(ClO₄)₂和Ba(ClO₄)₂的晶体结构未知，其³⁵Cl MAS核磁共振谱表明，这些盐中的每一种在不对称单元中都有一个单一的高氯酸根位点。Mg(ClO₄)₂和Ba(ClO₄)₂的³⁵Cl核磁共振数据表明这两个样品是同构的。对于已报道晶体结构数据的其他高氯酸盐，讨论了³⁵Cl核磁共振参数与晶体对称性之间的关系。
