title: Neutron diffraction studies on a 4-coordinate hydrogen atom in an yttrium cluster.
abstract: A four-coordinate hydrogen atom has been unambiguously located, by single-crystal neutron diffraction for the first time, in the center of the tetrahedral metal complex Y4H8(Cp')4(THF) [Cp'=C5Me4(SiMe3)]. The core of the molecule consists of a tetranuclear cluster with one interstitial, one face-bridging, and six edge-bridging hydride ligands. The compound was prepared via the reaction of YCp'(CH2SiMe3)2(THF) with gaseous H2. Neutron data were collected on a 4 mm3 crystal at the Quasi-Laue diffractometer VIVALDI at ILL (Grenoble)1a and on an 8 mm3 crystal at the SXD diffractometer at ISIS (Didcot). The final agreement factor is R = 8.9% for 4171 reflections. The existence of 4-coordinate hydrogen now completes the series of high-connectivity hydride ligands located in the interstitial cavities of molecular cluster complexes. We had previously reported the existence of 6-coordinate hydrogen in the octahedral cavity of [HCo6(CO)15]- in 1979, and 5-coordinate hydrogen in the square pyramidal cavities of [H2Rh13(CO)24]3- in 1997, also via single-crystal neutron analyses.
authors.affiliation: Department of Chemistry, University of Southern California, Los Angeles, California, USA.
authors.forename: Muhammed
authors.initials: M
authors.lastname: Yousufuddin
authors.forename: Matthias J
authors.initials: MJ
authors.lastname: Gutmann
authors.forename: Jens
authors.initials: J
authors.lastname: Baldamus
authors.forename: Olivier
authors.initials: O
authors.lastname: Tardif
authors.forename: Zhaomin
authors.initials: Z
authors.lastname: Hou
authors.forename: Sax A
authors.initials: SA
authors.lastname: Mason
authors.forename: Garry J
authors.initials: GJ
authors.lastname: McIntyre
authors.forename: Robert
authors.initials: R
authors.lastname: Bau