204455-57-2Relevant articles and documents
Cyanide Ligand Basicities in Cp′M(L)2CN Complexes (M = Ru, Fe). Correlation between Heats of Protonation and vCN
Nataro, Chip,Chen, Jiabi,Angelici, Robert J.
, p. 1868 - 1875 (2008/10/08)
Basicities of the cyanide ligands in a series of Cp′M(L)2CN complexes were investigated by measuring their heats of protonation (-δHCNH) by CF3SO3H in 1.2-dichloroethane solution at 25.0 °C to give Cp′M(L)2(CNH)+CF3SO3 -, in which the N-H+ group is probably hydrogen-bonded to the CF3SO3- anion. Basicities (-δHCNH) of the CpRu(PR3)2CN complexes increase from 20.5 (PPh3) to 22.4 (PMe3) kcal/mol with increasing donor abilities of the phosphine ligands. Basicities of all the Cp′Ru(PR3)2CN complexes, where Cp′ = Cp or Cp*, are linearly correlated with their vCN values; the nonphosphine complexes. CpRu(l.10-phen)CN and CpRu(COD)CN, do not follow the same correlation. For a large number of Cp′M(L)2CN complexes (M = Ru, Fe, L2 = mono- and bidentate phosphines, CO, 1,10-phen, and COD), their vCN values parallel vCN values of their protonated Cp′M(L)2(CNH)+ analogues. Also, 31P NMR chemical shifts of the unprotonated Cp′M(PR3)2-CN and protonated CpM(PR3)2(CNH)+ complexes are linearly related. Despite the high basicity of Ru in Cp*Ru-(PMe3)2Cl (30.2 kcal/mol), the CN- in Cp*Ru(PMe3)2CN (25.0 kcal/mol) is the site of protonation: factors that determine whether protonation occurs at the Ru or the CN- are discussed.
