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)

The P-31 NMR spectra of CpRu(PR3)(2)Cl and Cp*Ru-(PR3)(2)Cl complexes with PR3 = PMe3, PPhMe2, PPh2Me, PPh3, PEt3, (PBu3)-Bu-n have been measured; these data correlate with and can be used to predict Ru-P bond distances and enthalpies. Their P-31 NMR coordination chemical shifts (Delta(ppm) = delta(complex) - delta(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 Delta (ppm) and Ru-P distance can be extended to include the first-generation Grubbs metathesis catalyst (PCy3)(2)Cl2Ru=C(H)Ph and four of its derivatives, (PCy3)(2)Cl2Ru=C(H)(p-C6H4X) (X = OCH3, CH3, Cl, Br), the four related Fischer carbenes (PCy3)(2)Cl2Ru=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)(2)Cl 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 Delta (ppm) values. The P-31 NMR shifts for six phosphines correlate nearly linearly with their crystallographic cone angles, allowing prediction of cone angles from P-31 NMR data.