Problem Set 4 chem173A 2009

Problem Set 4 chem173A 2009 - Problem Set 4 Due: Nov 30,...

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Problem Set 4 Chemistry 173a/268a Due: Nov 30, 2009 1) (8 points) (a) Predict the 19 F NMR spectrum of BF 4 - . Hint: both 11 B (I = 3/2, 80% abundance) and 10 B (I = 3, 20% abundance) are NMR active. (b) Predict the 11 B NMR spectrum of BF 4 - and BF 3 ( 19 F: I = ½, 100% abundance). 2) (a) (2 points) Predict the number of lines ( and their relative intensities) in the 1 H NMR spectrum for a 1 H nucleus coupling to three equivalent 2 H nuclei (I = 1). (b) (2 points) Predict the number of lines ( and their relative intensities) in the 13 C NMR spectrum for a 13 C nucleus coupling to two equivalent 7 Li nuclei (I = 3/2). 3) (4 points) The ESR spectrum of [{((Me 3 Si) 2 N) 2 (OC 4 H 8 )Y} 2 ( μ - 15 N 2 )] - , where N 2 is isotopically labeled with 15 N, is shown below. ( 15 N: I = ½ and 89 Y: I = ½, 100% abundance). Explain the observed coupling. 4) (4 points) Pyridine forms a stronger Lewis acid-base complex with SO 3 than with SO 2 . However, pyridine forms a weaker complex with SF 6 than with SF
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This note was uploaded on 01/09/2011 for the course CHEM 173A taught by Professor Unknown during the Spring '08 term at UCSB.

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