1. The problem statement, all variables and given/known data The attempt at a solution 1) Is the above excerpt describing pi-backbonding? It seems to be describing some form of backbonding because the electron density is moving away from the positively charged metal cation (rather unexpected based on superficial Columbic analysis). 2) Is pi-backbonding more favorable for metals in a low rather than a high oxidation state because such metals still have substantial electron density that needs to be stabilized - and preferably stabilized by something more electronegative than a metal? 3) Metal d-orbitals overlap with p or d-orbitals of the non-metal. How does this work? I always see diagrams such as these: Is the overlap between the metal d-orbital and non-metal p-orbital as poor as depicted? Are the d-orbitals really at a 45 degree angle relative to the p-orbital? 3b) Why does there seem to be 4 bonds in the carbon monoxide ligand in the above diagram? Shouldn't there be instead 2 lines between C and O not 3 lines and two aligned p-orbitals? (Probably being a bit nit-picky here). 4) How well is the above excerpt written? I feel that two improvements could be made: A) The passage seems to imply that Bronsted acidity and basicity do not depend on the corresponding base or acid. Wrong implication. HCl in HBr solvent won't be a strong acid. B) Why electron density might just "drift" to the non-metal could be explained explicitly. I.e. electronegativity.