Bridging Xe atom as electron-donor: The potential bond type of M–Ng–M in organometallic noble gas complexes

Bridging Xe atom between two Lewis acidic transition metal centers is theoretically proposed. The structures, stabilities and bonding of Cr2(CO)10Xe, Cr2(CO)8Xe2, as well as Cr2(ŋ4-C4H4)4(PF3)2Xe and Cr2(ŋ4-C4H4)4Xe2 containing bridging Xe are detailed studied. Xe atom acts as an electron donor in above complexes. The predicted bond energies for Cr–Xe in these complexes with bridging Xe are lower compared with the terminal Cr(CO)5Xe. However, the dissociation energies of Cr2(ŋ4-C4H4)4(PF3)2Xe and the intermediate product Cr2(ŋ4-C4H4)4Xe, are nearly the same to the existing terminal Cr(CO)5Xe. As being relatively stable against dissociation, once generate, the bridging Xe atom might exist at low temperature like the terminal Xe.