IR Spectra of n-Bu 4 M (M = Si, Ge, Sn, Pb), n-BuAuPPh 3 -d 15 , and "n-Bu" on a Gold Surface.

Observed and DFT-calculated IR spectra of n-Bu4 M (M = Si, Ge, Sn, Pb), (CH3 CH2 CH2 13 CD2 )4 Sn, and n-BuAuPPh3 -d15 are reported and assigned. The asymmetric CH stretching vibration of the CH2 group adjacent to the metal atom appears as a distinct shoulder at ∼2934 cm-1 , whereas for other CH2 groups it is located at ∼2922 cm-1 . The characteristic peak at ∼2899 cm-1 is attributed to an overtone of a symmetric CH2 bend at ∼1445 cm-1 . In n-BuAuPPh3 -d15 , the CH stretching vibrations of the butyl group are shifted to lower frequencies by ∼10 cm-1 , and two possible rationalizations are offered.