897015-18-8Relevant articles and documents
An acidity scale of phosphonium tetraphenylborate salts and ruthenium dihydrogen complexes in dichloromethane
Li, Tianshu,Lough, Alan J.,Zuccaccia, Cristiano,Macchioni, Alceo,Morris, Robert H.
, p. 164 - 175 (2006)
Equilibrium constants (KDM) for reactions between acids and bases of the title compounds in CD2Cl2 (DM) have been determined by 31P and 1H NMR spectroscopy at room temperature. [HPCy3]BPh4 and [HPCy3]BF 4, with pKDM assigned by literature convention to 9.7, have been used as the anchor compounds for the pKDM determinations. A continuous scale of pKDM values covering the range 9.7 to 5.7 is created with the acidic compounds [HPR3]BPh4. Those acids with pKDM greater than 6 are stable, while those with more acidic cations HPR3+ protonate BPh4- to produce R3PBPh3 and benzene. The literature pK THF values reported for [HPBu2Ph]BPh4, [HPMePh2]BPh4, and [HPEtPh2]BPh4 are questionable because of this protonation reaction. NOE and PGSE 1H NMR techniques are used to show that [HPCy2Ph]BPh4 in DM exists as ion pairs and higher aggregates up to quadrupoles at the concentrations used in the acid-base studies. The new dihydrogen complexes [Ru(H2)Cl(PPh3)2(dach)]BF4 (dach = (1R,2R)-(-)-diaminocyclohexane) and [Ru(H2)Cl{tmeP 2(NH)2}]BF4 (tmeP2(NH)2 = PPh2C6H4CH2NHCMe 2CMe2NHCH2C6H4PPh 2) were prepared by reaction of RuHCl(PPh3) 2(dach) and RuHCl{tmeP2(NH)2} with HBF 4. Their crystal structures are reported, and the pKDM values of their BPh4- salts were determined to be 8.6 and 6.9, respectively.
