A series of bidentate alkanethiolate compounds Mo[BH(Me2pz)3](NO)[SRS], [SRS]2− = [S(CH2)2CONH(CH2)2S]2− (1), [S(CH2)5S]2− (2), and [S(CH2)6S]2− (3), have been synthesized in order to determine the effects of N-H⋯S hydrogen bonding on redox potentials in metal-thiolate complexes. Complex 1 was structurally characterized by X-ray crystallography. It crystallizes in the space group P21\c with a = 11.878(2) Å, b= 10.8040(10) Å, c = 21.453(4) Å, a = 90°, β = 105.54°, γ = 90°, V = 2652.4(7) Å3, Z = 4, and R = 0.0374. Redox potentials of −0.793 V (1), −0.930 V (2), and −1.013 V (3) (relative to SCE) were measured in CH3CN by cyclic voltammetry. A comparison of complexes 1–3 by solution vibrational spectroscopy shows that the high redox potential of 1 may be attributed to the presence of N-H⋯S hydrogen bonds. The nitrosyl stretching frequency, v(NO), was assigned in the resonance Raman spectra of complexes 1–3. This band decreased in frequency in parallel with the decrease in redox potential. For complex 1 in solution the values of the amide N-H stretching frequency, v(NH), 3434 and 3308 cm−1 indicates a hydrogen bonding equilibrium constant of K = [NHbonded]/ [NHfree] = 6.7.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry