Particularly in view of potential applications in catalysis, we were also interested in the binding to weaker-coordinating neutral substrates. While for catalysis obviously the association in the transition state is decisive, the substrates may still provide a first indication of the feasibility of a multidentate interaction. Thus, NMR titrations with model substrates like acetone and acetonitrile were performed in deuterated toluene (Table ). While the association constants of both bidentate systems m-1 and p-1 were expectedly much lower compared to the complexes with anions (Table , entries 1-4), m-1 was still binding both acetonitrile and acetone stronger than p-1 by an order of magnitude. This hints towards a more fitting binding pocket for m-1 and is in line with other catalyst structures that also bind carbonyl groups better with a meta-instead of a para-benzene core . When tridentate Lewis acid 3 was titrated against the neutral guests, its binding data to acetone or acetonitrile approximately matched that of m-1, suggesting that bidentate coordination might be present in solution. Finally, the complex formation of halogen bond donor 3 with trans-nitrostyrene was also explored, as the latter acts as substrate for a benchmark nitro-Michael reaction. Even though the obtained binding constant of 7.3 M -1 was somewhat lower than the one of a bidentate iodine(III)-based catalyst (K = 29 M -1 ), it still seemed promising enough to also test the carborane halogen bond donors in such reactions.