Detection of an unusually low ν(HH) stretching mode in the molecular dihydrogen complex [Ru(C5H5)(Ph2PCH2PPh2)(η2-H2)]BF4 by near infrared Fourier-Transform Raman spectroscopy☆

Abstract An unusually low ν(HH) stretching mode has been detected in the Raman spectrum of the molecular dihydrogen complex, [Ru(C 5 H 5 )(Ph 2 PCH 2 PPh 2 )( η 2 -H 2 )]BF 4 , at 2082 cm −1 which shifts to 1530 cm −1 upon η 2 -H 2 to η 2 -D 2 substitution. Other isotope-sensitive modes associated with the triatomic RuH 2 moiety are also detected at 1358, 679, 486, and 397 cm −1 , which are assigned to ν as (RuH 2 ), ν s (RuH 2 ), δ(RuH 2 ) and δ(RuH 2 ) modes, respectively.