Unlocking the metallaboratrane cage: reversible B-H activation in platinaboratranes

The reaction of the new platinaboratrane salt [PtH(PTol(3)){B(mt)(3)}]Cl(Pt -> B)(8) (mt = methimazolyl, Tol = C6H4Me-4) with 2 equivalents of PR3 (R = Me, Et) affords, via hydride migration to boron and ligand substitution, the salts [Pt(PR3)(2){kappa(2)- S, S'-HB(mt)(3)}]Cl, which slowly undergo B-H reactivation, to afford, ultimately, the platinaboratrane salts [PtH(PR3){B(mt)(3)}]Cl(Pt -> B)(8).