February 28, 2020, 05:41:12 PM
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Topic: NMR DEPTQ135 Shift after Coordination  (Read 583 times)

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Offline ethan.millerirl

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NMR DEPTQ135 Shift after Coordination
« 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?
« Last Edit: September 26, 2019, 09:23:06 AM by sjb »

Offline hollytara

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Re: NMR DEPTQ135 Shift after Coordination
« Reply #1 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.

Offline OrganicDan96

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Re: NMR DEPTQ135 Shift after Coordination
« Reply #2 on: September 26, 2019, 09:56:15 AM »
i have seen this before, you can invert the phase in nmr software.

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