Synthesis and Structure Elucidation of Large Phosphorus Macrocycles

The simple reaction between 1,ω-diamino derivatives and R-bis-(dimethylamino)-phosphane (R = CH₃, C₆H₅), followed by an oxidation step led to the formation of the expected macrocyclic phosphorus compounds. By this way 17- to 27-membered macrocycles were easily obtained. During the synthesis, the formation of dimeric (40- and 52-membered rings) and trimeric (78-membered rings) macrocyclic species were obtained from 3 and 5 and fully characterized by NMR and mass spectrometry. The P(III) phosphorus species exchange in solution and the macrocycle/oligomers ratio is temperature and concentration dependent. The crystal structure analysis of macrocycles 1, 5, 7 and 8 show that voids are minimized in the solid so that the macrocyclic cavity is filled up with part of the molecule itself or with a guest molecule, when the size of the macrocycle does not allow molecular folding for self-filling the cavity. Dedicated to the memory of Prof. Jean-Bernard Robert