NUCLEAR SPECTROSCOPY

 

NUCLEAR SPECTROSCOPY

 

TECHNIQUES USED TO PREPARE COORDINATION COMPOUND

 

NUCLEAR SPECTROSCOPY

 

There are three “3” methods of molecular spectroscopy which we study in Nuclear Spectroscopy.

·           NMR Spectroscopy

·           NQR Spectroscopy

  Mossbauer Spectroscopy

NMR SPECTROSCOPY

 

NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

 

·         Why we use NMR Spectroscopy?

              

  We use NMR Spectroscopy to examine that what could be the possible structure of any Chemical Compound.

 

Instrumentation of NMR Spectroscopy

Instrumentation of NMR Spectroscopy

 

 

 

           WHAT TYPE OF SAMPLE IS REQUIRED?
               

 

·         To study any coordination compound we required NMR active atom.

·         NMR technique is not applicable to all type of elements. Although it is rare to found a compound.

·         Its is applicable to those compounds whose atom have odd number of protons and neutrons in their nuclease because it do not make pair during spinning and can easily spin in NMR Spectroscopy.

·         Method depend on the spinning of sample inclined to the correct angle to applied magnetic field.

 

 

·         When we put a sample in an instrument contain nucleus and nuclease is having a proton which is charged particle which rotate around their axes.

·         It behave like  magnet and rotate in the influence if magnetic field.

·         When we put any coordination compound to examine it in NMR Instrument.

·         α-spin or low-energy spin:

 

·         So small magnet (protons) of a nucleus comes in influence of large magnets of NMR Machine so it set its direction toward the direction of magnetic filed which is downward so called α-spin or Low-energy spin.

 

 

 

·         So when these protons of coordination compound get UV energy so amount of these rays can be measured in terms of ΔE=hѴ.

·         β-spin or high-energy spin:

 

·         When we put a UV rays on the nucleus of any coordination compounds it gain or absorb energy and moves in upward direction comes in High-energy state so this is called as β-spin.

·         When these nucleus of any coordination compounds comes in high state or get energy they are said to be that they comes in resonance.

·         So NMR Spectroscopy means that the nucleus of an coordination compound comes in resonance by the influence of magnetic filed.

·         While spectroscopy is a machine through which we study any matter and electromagnetic radiation.

 

 

 

 

 

NMR Spectrum

The peaks which are showing first are the peaks of first nucleus of coordination compounds and the peaks after showing are the peaks of next nucleus of coordination compounds.

 

·         Chemical shift:

·         Chemical shift is that the peaks of NMR are rather up-filled or dwon-filled.

·         The peaks filled first are called up-filled and the peaks filled later/next are called down-filled.

Up-filled are the peaks of those compounds which utilize low-energy to comes in resonance.
Down-filled are the peaks of those compounds which utilize high-energy to come in resonance.

 

 

EXAMPLE OF TUNGSTEN AND FLUORINE:

 

·         Complexes of WF₆, [WF₆L] where L is a ligand, exist and in which the tungsten atom might be seven coordinate. A low-resolution ¹⁹F spectrum shows three lines of relative intensity, which does not appear to be consistent with a seven-coordinate structures. The most likely structure is [WF₅L]⁺ F^-, in which the tungsten atom is octahedral coordinated by six ligands, five of which are fluorines. The four coplanar fluorines give rise to the largest peak and the axial fluorines to one of the others. The fluoride anion gives the final peak.  

 

 

        The fine structure of the peaks confirms this assignment as does the conductivity of the compounds in liquid sulfur dioxide and, finally, X-ray crystallography.

This example, as presented, depends on an interpretation of the number of observed peaks. In practice, empirical relationships between structure, chemical shifts and coupling constants would also be used in such structure determinations.