Correlations among 31P NMR Coordination Chemical Shifts, Ru–P Bond Distances, and Enthalpies of Reaction in Cp′Ru(PR3)2Cl Complexes (Cp′ = η5-C5H5, η5-C5Me5; PR3 = PMe3, PPhMe2, PPh2Me, PPh3, PEt3, PnBu3)

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• 作者：Alex D. Hunter ; Trevor Robert Williams ; Brandon M. Zarzyczny ; Hans W. Bottesch II ; Sara A. Dolan ; Kimberly A. McDowell ; Dominique Nicole Thomas ; Charles H. Mahler
• 刊名：Organometallics
• 出版年：2016
• 出版时间：August 22, 2016
• 年：2016
• 卷：35
• 期：16
• 页码：2701-2706
• 全文大小：372K
• 年卷期：0
• ISSN：1520-6041

文摘

The ³¹P NMR spectra of CpRu(PR₃)₂Cl and Cp*Ru(PR₃)₂Cl complexes with PR₃ = PMe₃, PPhMe₂, PPh₂Me, PPh₃, PEt₃, PⁿBu₃ have been measured; these data correlate with and can be used to predict Ru–P bond distances and enthalpies. Their ³¹P NMR coordination chemical shifts (Δ(ppm) = δ_complex – δ_free) show significant linear correlations with literature values of both the enthalpies of the ligand exchange reactions to form the Ru–P bonds and the average Ru–P bond distances from crystal structures. The strong correlation between Δ(ppm) and Ru–P distance can be extended to include the first-generation Grubbs metathesis catalyst (PCy₃)₂Cl₂Ru═C(H)Ph and four of its derivatives, (PCy₃)₂Cl₂Ru═C(H)(p-C₆H₄X) (X = OCH₃, CH₃, Cl, Br), the four related Fischer carbenes (PCy₃)₂Cl₂Ru═C(H)ER (ER = OEt, SPh, N(carbazole), N(pyrrolidinone)), the second-generation Grubbs catalyst (PCy₃)(IMes)Cl₂Ru═C(H)Ph, and its derivative (PCy₃)(IMes)Cl₂Ru═C(H)OEt. Other significant correlations in the Cp′Ru(PR₃)₂Cl complexes are found between the enthalpies of reaction and Ru–P bond distances and between the cone angle and the Ru–P enthalpy, Ru–P bond distance, and Δ(ppm) values. The ³¹P NMR shifts for six phosphines correlate nearly linearly with their crystallographic cone angles, allowing prediction of cone angles from ³¹P NMR data.