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Chemistry Forums for Students => Organic Chemistry Forum => Organic Spectroscopy => Topic started by: ethan.millerirl on September 25, 2019, 06:50:28 PM

Title: NMR DEPTQ135 Shift after Coordination
Post by: ethan.millerirl on September 25, 2019, 06:50:28 PM

I have synthesized bis(amidine) ligands for metal coordination. At each step, the molecule is characterized by NMR (1H, 13C, DEPTQ135, 2D Experiments). Analyzing with DEPTQ135 should show CH and CH3 peaks as positive, and C and CH2 as negative, and it looks right in the ligand experiment, but after coordination, the expected peaks are reversed, with CH and CH3 as negative, and C and CH2 as positive. Keep in mind, we are seeing the correct number of peaks in the expected regions. Is there any reason aside from a failed coordination experiment that this could happen?

Title: Re: NMR DEPTQ135 Shift after Coordination
Post by: hollytara on September 25, 2019, 10:13:14 PM

What solvent did you run the spectrum in?  Do those peaks point the expected way?  Sometimes using the wrong phase angle can invert the direction of the peaks.

Title: Re: NMR DEPTQ135 Shift after Coordination
Post by: OrganicDan96 on September 26, 2019, 09:56:15 AM

i have seen this before, you can invert the phase in nmr software.