Metallaboratranes: The M→B Dative Bond as a Ligand Activating Function in the Phosphaboration of Carbon Monosulfide

The reaction of Na[H 2 B(mt) 2 ] (mt = methimazolyl) with [RhCl(CO)(PPh 3 ) 2 ] proceeds via simple metathesis to provide the complex [Rh(CO)(PPh 3 ){H 2 B(mt) 2 }]; however, with [RhCl(CS)(PPh 3 ) 2 ] C,C-phosphaboration of the thiocarbonyl ligand occurs, with formation of the novel cage complex [RhH(PPh 3 ){η 2 ( C, S ),κ 2 S ‘, S ‘ ‘-SC(PPh 3 )BH(mt) 2 }].