Limitations of VSEPR in its description of bonding

There are several limitations of VSEPR in its description of bonding. The 2019 article attached (1A and 1B), explores the bonding in water and several small molecules with apparent conjugation – formamide, formic acid, anisole and furan. Consider water and one (1) other molecule as case studies with which to answer the following questions:

a) What is the main weakness of the VSEPR in each of your select cases? (8 marks)

b) How does the wavefunction approach to molecular orbitals support the idea of extended conjugation? (6 marks)

c) Examine the resonance forms presented for the conjugated molecule you have chosen and comment on the distribution of charges which occurs. (6 marks)

d) All the orbitals discussed in the article are “computationally accurate” using “natural bond orbitals” and an undefined abbreviated term, “B3LYP”. Define each of these terms at a level suited to a student doing CAPE-level chemistry, using an appropriate example. (15 marks)

e) The authors mention microwave spectroscopy as an experimental tool to check molecular structures. Write a short paragraph on how this works. (5 marks)

Sample Solution