Unravelling the Structure of Magnus’ Pink Salt

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• 作者：Bryan E. G. Lucier ; Karen E. Johnston ; Wenqian Xu ; Jonathan C. Hanson ; Sanjaya D. Senanayake ; Siyu Yao ; Megan W. Bourassa ; Monika Srebro ; Jochen Autschbach ; Robert W. Schurko
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：January 29, 2014
• 年：2014
• 卷：136
• 期：4
• 页码：1333-1351
• 全文大小：801K
• ISSN：1520-5126

文摘

A combination of multinuclear ultra-wideline solid-state NMR, powder X-ray diffraction (pXRD), X-ray absorption fine structure experiments, and first principles calculations of platinum magnetic shielding tensors has been employed to reveal the previously unknown crystal structure of Magnus鈥?pink salt (MPS), [Pt(NHb>3b>)b>4b>][PtClb>4b>], study the isomeric Magnus鈥?green salt (MGS), [Pt(NHb>3b>)b>4b>][PtClb>4b>], and examine their synthetic precursors Kb>2b>PtClb>4b> and Pt(NHb>3b>)b>4b>Clb>2b>路Hb>2b>O. A simple synthesis of MPS is detailed which produces relatively pure product in good yield. Broad ¹⁹⁵Pt, ¹⁴N, and ³⁵Cl SSNMR powder patterns have been acquired using the WURST-CPMG and BRAIN-CP/WURST-CPMG pulse sequences. Experimentally measured and theoretically calculated platinum magnetic shielding tensors are shown to be very sensitive to the types and arrangements of coordinating ligands as well as intermolecular Pt鈥揚t metallophilic interactions. High-resolution ¹⁹⁵Pt NMR spectra of select regions of the broad ¹⁹⁵Pt powder patterns, in conjunction with an array of ¹⁴N and ³⁵Cl spectra, reveal clear structural differences between all compounds. Rietveld refinements of synchrotron pXRD patterns, guided by first principles geometry optimization calculations, yield the space group, unit cell parameters, and atomic positions of MPS. The crystal structure has P-1 symmetry and resides in a pseudotetragonal unit cell with a distance of >5.5 脜 between Pt sites in the square-planar Pt units. The long Pt鈥揚t distances and nonparallel orientation of Pt square planes prohibit metallophilic interactions within MPS. The combination of ultra-wideline NMR, pXRD, and computational methods offers much promise for future investigation and characterization of Pt-containing systems.