Factors affecting the ability of potentially chelating amine ligands to form chelated fluoroboron cations are explored by 19F and 11B NMR spectroscopy and fast atom bombardment mass spectrometry (FAB-MS). Five-membered chelate rings form much more readily than six-membered. Some potentially chelating ligands give rise to additional fluoroboron species by various redistribution and decomposition reactions.Key words: chelated fluoroboron cations, 19F NMR, 11B NMR; FAB-MS, N,N,N',N'-tetraethylethylenediamine.