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Complexes of SiH22+ with carbodiphosphorane and analogues {R(PPh3)2} in unusual bonding mode (E = C, Si, Ge, Sn, Pb)

Nguyen Thi Ai Nhung, Nguyen Van Ly, Tran Duong, Pham Van Tat

Abstract


Quantum chemical calculations at the BP86 level with various basis sets (SVP, TZVPP) were carried out for complexes of carbodiphosphorane analogues E(PPh3)2 with E = C, Si, Ge, Sn, Pb. The equilibrium geometries of the complexes [SiH22+–{E(PPh3)2}] (Si2+-1E) possess the carbodiphosphorane ligand 1C is slightly bonded in a tilted way to SiH22+ in the complex Si2+-1C, whereas the heavier group-14 ligands E(PPh3)2 (E = Si, Ge, Sn, Pb) in the complexes Si2+-1Si – Si2+-1Pb are strongly bonded in side-on fashions. The surprising structures SiH22+-tetrylone complexes possess a strong Si-C1 bond between the Si atom of the SiH22+ fragment and atom C1 of the phenyl group. The trend of the bond dissociation energies  (BDEs) for the Si-E bond in the Si2+-1E complexes is Si2+-1C ~ Si2+-1Si ~ Si2+-1Ge < Si2+-1Sn < Si2+-1Pb. Bonding analysis of the complexes shows that the Si-E bonds have a significant contribution from H2Si2+←E(PPh3)2 π-donation.

Keywords: Donor-acceptor interactions; bonding analysis; density functional theory, bond dissociation energy.

Keywords


Donor-acceptor interactions; bonding analysis; density functional theory, bond dissociation energy