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)

Abstract

The 31P NMR spectra of CpRu­(PR3)2Cl and Cp*Ru­(PR3)2Cl complexes with PR3 = PMe3, PPhMe2, PPh2Me, PPh3, PEt3, P n Bu3 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) = δcomplex – δfree) 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.

Coordination Ability of 10-EtC(NHPr)=HN-7,8-C2B9H11 in the Reactions with Nickel(II) Phosphine Complexes

“…In the 31 P NMR spectra, the signals of phosphine ligands appeared at 29.3 ppm for 2, at −2.6 ppm for 3 and at 11.9 ppm for 4. Such chemical shifts were in good agreement with the data for similar phosphine complexes of other transitional metals [24].…”

Ruthenium (II) complexes bearing thioether‐appended α‐iminopyridine ligands: Arene precursors permit access to κ2‐N,N and κ3‐N,N,S complexes

“…To this end, addition of two equivalents (0.05 mmol) of triphenylphosphine to a solution of 1 in CDCl 3 (~0.75 M) resulted in a rapid color change from dark green to purple upon heating at 70 °C for one hour. The 1 H NMR spectrum of this solution revealed complete disappearance of signals attributed to Ru‐bound arene C–H's (δ = 5.81, 5.66, 5.58, and 5.29, Figure ), while the 31 P{ 1 H} NMR spectrum exhibited a new signal at δ = 17.40 consistent with the chemical shifts observed for related arene Ru(II) complexes . Combined, these data suggest loss of the p ‐cymene ligand to form a complex such as [ L1 ‐Ru(PPh 3 ) 2 Cl] BF 4 with two equivalent triphenylphosphine ligands, likely requiring a κ 3 ‐N,N,S binding mode to complete the coordination sphere.…”

Structure, Electronics and Reactivity of Ce(PNP) Complexes

“…31 P NMR data were recently applied for correlation of both steric and electronic parameters of phosphine ligands in transition‐metal complexes, particularly, the Ru⋅⋅⋅P distances and coordination chemical shifts were linearly correlated . In this work we found that there is a positive correlation between the δ ( 31 P) chemical shifts for PNP−Ce III complexes 1 – 6 measured in benzene and experimentally estimated Ce III −P bond distances ( R= 0.965, Figure ).…”