Question

Using the tree approach for predicting first-order NMR spectra for molecules and draw the requested spectra for the following molecules #1-#3 in the space provided (do not use backside of pages). All spectra are collected with no {1H} (proton decoupling). The NMR active nuclei are all I = 1⁄2, i.e., dipolar, so Pascal’s triangle applies. Consider only 1-bond coupling constants 1JAB, and ignore ≥2- bond coupling constants (EXCEPT where noted in #2); label the chosen coupling constant on each branch of your tree. D = deuterium = 2H; assume that quadrupolar D is not involved in coupling to other nuclei. Carbon-13 is at natural abundance, unless noted otherwise (#2), so it is not involved in coupling, but its resonances can be observed by 13C NMR spectroscopy. Provide the coupling constant order that you have assumed in predicting your spectrum.

2) The liquid phosphorus ylid (UCD,),31r-13CH2, enriched to 100% ㎍ at all carbon sites; indude also 3) fac-RhH,[P(CD3)3]3 a) 1 Rh NMR spectrum (1 3Rh, î " is 100% abundant) 2-bond couplings with your 1-bond couplings the 2-bond coupling constants will be considerably smaller b) H NMR spectrum a) NMR spectrum b) H NMR spectrum c) PNMR spectrum c SCNMR spectrum 4) Why does the H NMR spectrum of the hydrido ligand in cis-RhH(CO(PMea)l consist of B resonances of equal intensity? -bond and 2-bond couplings are both involved in this question; assume that ! C is at natural abundance of 1%, and thus not involved in the coupling, and that Pt is 100% 1 Pt, spin 1 /2)). Your answer:

Answer 1

Organic compounds are often identified using spectroscopy. The process of testing compounds using spectroscopy is fairly simple (the compounds are placed into the machine and the read-out is printed). The difficult part comes in learning how to read the print-out and determining what it is telling you.

In infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy, we identify the compound based on specific groups. Certain ranges of frequencies for each type of spectroscopy indicate different groups