Probing Individual Steps of Dynamic Exchange with 31P EXSY NMR Spectroscopy: Synthesis and Characterization of the [E7PtH(PPh3)]2- Zintl Ion Complexes [E = P, As]

摘要: Ethylenediamine (en) solutions of E73- (E = P, As) react with Pt(PPh3)2(C2H4) in the presence 4,7,13,16,21,24-hexaoxa-1,10-diazobicyclo[8.8.8]hexacosane (2,2,2-crypt) to give transition-metal Zintl ion complexes [P7PtH(PPh3)]2- (1) and [As7PtH(PPh3)]2- (2) as isomorphic [K(2,2,2-crypt)]+ salts, respectively. The hydride ligand originates from solvent, deuterium labeling studies show that order hydrogen sources follows sequence en > CH3CN DMSO DMF synthesis 1. [E7PtH(PPh3)]2- anions have C1 point symmetry unperturbed nortricyclane-like ligands bound η2 square planar PtIIH(PPh3)+ centers. Complex 1 is dynamic solution whereby PtH(PPh3)+ fragment shifts top bottom P7 cluster (an → η4 shift) spins P4 face a concerted process apparent C2v symmetry. We shown 31P EXSY NMR experiments at −78 °C permit separation two processes shifting ∼20 times faster than spinning...