The electronic effect of substituting CH with N in poly(pyrazolyl)-borato ligands and their transition-metal complexes is shown to be a decrease in energy of the filled metal and ligand orbitals. This conclusion is based on the cyclovoltammograms and photoelectron spectra of bis(hydrotris(azolyl)borato)-iron(II) and -cobalt(II) complexes (azolyl = pyrazolyl and 1,2,4-triazolyl) and on MO calculations. 57Fe Mössbauer spectra of bis(hydrotris(1,2,4-triazolyl)-borato)iron(II) show that there is a fine-tuning of the HOMO–LUMO gap by a shift in transition temperature for the spin equilibrium. 15N NMR spectroscopy supports the assignment of a higher negative charge to the exodentate N-4 nitrogen than to the endodentate N-2 or N-3 positions in the poly(azolyl)borato anions, where azolyl is 1,2,4-triazolyl or tetrazolyl. The electron withdrawing effect of the additional nitrogen atoms and the in-corporation of water of crystallization by O–H ⃛ N bonding both assist in the formation of (azolyl)C–H ⃛ O bonds.