title: Halide coordination of perhalocyclohexasilane Si6X12 (X=Cl or Br).
abstract: The addition of halide anions (X' = Cl(-), Br(-), or I(-)) to perhalocyclohexasilane Si(6)X(12) (X = Cl or Br) led to the formation of complexes comprising [Si(6)X(12)X'(2)](2-) dianions. An upfield shift in the (29)Si NMR spectra was noted upon coordination, and structural determination by X-ray crystallography showed that the dianions adopt an "inverse sandwich" structure where the six cyclic silicon atoms form a planar hexagon with the two halide anions X' located on the 6-fold axis equally disposed above and below the plane of the Si(6) ring. Additionally, these apical X' atoms are within the van der Waals bonding distance to the silicon ring atoms, indicating a strong interaction between X' and silicon atoms. These results detail crystallographic variations within the halogen series providing further insight into the nature of the Lewis acid sites above and below the Si(6)X(12) ring, where interactions with hard Lewis bases such as halide anions are observed. Interestingly, the stereochemistry of the silicon atoms in [Si(6)X(12)X'(2)](2-) is not affected much by the size or electronegativity of the halogen atoms.
authors.affiliation: Center for Nanoscale Science and Engineering, North Dakota State University, 1805 NDSU Research Park Drive, Fargo, North Dakota 58102, USA. xuliang.dai@ndsu.edu
authors.forename: Xuliang
authors.initials: X
authors.lastname: Dai
authors.forename: Seok-Bong
authors.initials: SB
authors.lastname: Choi
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Braun
authors.forename: Pooja
authors.initials: P
authors.lastname: Vaidya
authors.forename: Svetlana
authors.initials: S
authors.lastname: Kilina
authors.forename: Angel
authors.initials: A
authors.lastname: Ugrinov
authors.forename: Douglas L
authors.initials: DL
authors.lastname: Schulz
authors.forename: Philip
authors.initials: P
authors.lastname: Boudjouk