Singlet and Triplet Anthrone

try to draw resonance contributors for both ground state and triplet anthrone. Then display a spin density surface for the triplet state of anthrone. (Note that the spin density surface shows the location of both unpaired electrons, one of which may be in a 7t orbital and one of which may be in a o orbital.) Where are the two unpaired electrons Are they localized or delocalized Given that spin delocalization generally leads to stabilization, would you expect the triplet state of anthrone to be stable  

Compare the geometries of triplet and ground state singlet anthrone. Where do they differ the most Focus on the carbonyl group. Has the CO bond distance altered Does the molecule incorporate a fully-developed CO n bond (as in ground state singlet anthrone), or a single bond (as in phenol) Is the carbonyl carbon planar or puckered Rationalize your observations. 

Spin density surface for triplet anthrone locates the two unpaired electrons. 

The NMR spectrum of the cyclophane shows three signals at 6 4.27, 6.97, and 7.24 (1 2 1 ratio) due to the benzene ring hydrogens. Examine cyclophane and identify which hydrogens are responsible for each signal. 

The NMR spectra of cis and trans-diphenylbenzo-cyclobutene are nearly the same except for the chemical shifts of the hydrogens on the four-membered ring. The hydrogens in one compound produce a singlet at 6 4.44, while those in the other compound produce a singlet at 6 5.2. Examine the geometries of cis and trans diphenylbenzo-cyclobutane. Which compound is responsible for which NMR spectrum Explain your reasoning. 

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