177495-95-3Relevant academic research and scientific papers
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]
Kesanli,Charles,Lam,Bott,Fettinger,Eichhorn
, p. 11101 - 11107 (2000)
Ethylenediamine (en) solutions of E73- (E = P, As) react with Pt(PPh3)2(C2H4) in the presence of 4,7,13,16,21,24-hexaoxa-1,10-diazobicyclo[8.8.8]hexacosane (2,2,2-crypt) to give the 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 the solvent, and deuterium labeling studies show that the order of hydrogen sources follows the sequence en > CH3CN > DMSO > DMF in the synthesis of 1. The [E7PtH(PPh3)]2- anions have C1 point symmetry with unperturbed nortricyclane-like E73- ligands bound η2 to square planar Pt(II)H(PPh3)+ centers. Complex 1 is dynamic in solution whereby the PtH(PPh3)+ fragment shifts from the top to bottom of the P7 cluster (an η2 → η4 → η2 shift) and spins in the P4 face in a concerted process to give apparent C(2v) symmetry. We have shown that 31P EXSY NMR experiments at -78 °C permit the separation of the two processes and show that shifting is ~20 times faster than spinning (k(shift) = 160 s-1, k(spin) = 8 s-1).
