Using spectroscopic experiments and computer simulations, Andrei Tokmakoff at the University of Chicago and colleagues show that the line between a hydrogen bond and a covalent bond is blurrier than your textbook suggests (Science 2021, DOI: 10.1126/science.abe1951) .
Recent work on Hydrogen bonding. Andrei Tokmakoff relates hydrogen bonding to covalent bond in F-H-F(-) ion in water using Femtosecond Infrared Spectroscopy