Determines the location and connectivity of nuclei within a molecule
UV-Vis spectrometry
Determines bond patterns within a molecule
What kind of waves does NMR use?
Radio
What is required for NMR to work?
Nuclear spin and a atom with ODD atomic mass or atomic number
What do the levels of Nuclear spin range from?
0-2
What is the equation for energy state?
I= 2I+1
For Hydrogen: 2(.5)+1=2
Two energy states
What is the spectroscopy definition of resonance?
When the larmor (rotational frequency) is equal to the applied (radio frequency)
The frequency of the nucleus spinning is equal to the frequency of the radio waves being applied to it
FT NMR (Fourier Transform)
All nuclei are hit with a pulse, which then listens for the relaxation of the nuclei and records them all at once, as opposed to one by one as it used to be with continuous wave NMR (where frequencies had to be blasted one at a time)
Interpretation of NMR:
Number of different protons:
Determined by the number of group signals in the NMR spectrum
Interpretation of NMR:
Chemical shift:
The position of the signal groups on the line
Downfield = DEshielded
Upfield= shielded
Interpretation of NMR:
Integration:
Number of protons that are in each signal
Integration of NMR:
Spin-spin coupling:
Patterns within the signals that provide structural information about the molecule
ex: You would know how many proton neighbors something has by the amount of spikes that are there
What is tetramethasilane (TMS) used for?
It is used to be the internal reference when looking at chemical shifting. It is always at zero ppm and always has one signal
What are the key electron effects? In regards to deshielding and proximity
The more electronegative the atom, the more it will deshield the H
The closer H is to the electronegative atom, the more it will feel that effect of the electronegative pull and vice versa
Diagmatic anisotropy
When the electrons in a pi system (double bonds) are subjected to a magnetic field, that begin to rotate a lot
Because they are not rotating in all the same space, it means that certain regions will have different magnetic strengths
Does the circulation of pi bonds induce it's own magnetic field?