Covalent bonding is essentially the sharing of electrons between atoms to create a chemical bond. A covalent bond that shares two electrons would create a stronger bond than one whose bond has an odd number of electrons. A dihydrogen cation would only share one electron and therefore would be considered a weaker bond. Hydrogen has only one electron. When hydrogen is given a positive charge it is due to the loss of an electron which means it would no longer have an electron.
