Complexes of dimethylsulfoxonium methylide (1) and organoboranes are crystalline for ylide· BH3 (2), ylide· BPh3 (3), ylide· B (C6F5) 3 (4), and ylide· BF3 (5). These complexes undergo exothermic rearrangement by 1, 2-migration upon heating to produce homologated organoboranes and dimethylsulfoxide. Non-isothermal kinetic analysis of the differential scanning calorimetry (DSC) data for ylide· BPh3 (3) and ylide· B (C6F5) 3 (4) complexes ...