Temperature-dependent elongation of the H-H bond in dihydrogen complexes of Ru(II) bearing an NHC ligand: Effect of the NHC and trans ligands

摘要: Ruthenium hydride complexes bearing an N-heterocyclic carbene ligand RuHCl(CO)(IMes)(PPh3)(L/L')] (L = py, 2; 4Mepy, 3; L' MeCN, 4; Me3CCN, 5) have been synthesized in high-yields via reaction of RuHCl(CO)(IMes)(PPh3)] (1) with pyridyl ligands L py and 4Mepy) or nitrile (L' MeCN Me3CCN). The L/L' are labile all the ruthenium complexes; they can be easily replaced by Lewis bases. X-ray structures 2 3 show intramolecular pi-pi interactions between aromatic ring PPh3, IMes, ligands. protonation 2-5 gives corresponding dihydrogen type RuCl(eta(2)-H-2)(CO)(IMes)(PPh3)(L/L')]OTf] 6; 7; 8; 9). In complexes, H-H bond distances eta(2)-H-2 is temperature-dependent 0.98 angstrom to 0.93 temperature range 183-233 K. Attempts synthesize analogous phosphine resulted a mixture cis trans- RuHCl(CO)(PPh3)(2)(L)] 10/11 (trans(HCl)/cis(HCl)); 12/13 (trans(HCl)/cis(HCl))] complexes. A comparative study has done get insight into 6-8 synthesizing RuCl(eta(2)-H-2)(CO)(PPh3)(2) (L)](OTf) 15; 17). All characterized using NMR spectroscopy. crystal 2, 3, 12 also determined.