title: Encapsulation of hydride by molecular main group metal clusters: manipulating the source and coordination sphere of the interstitial ion.
abstract: The sequential treatment of Lewis acids with N,N'-bidentate ligands and thereafter with ButLi has afforded a series of hydride-encapsulating alkali metal polyhedra. While the use of Me3Al in conjunction with Ph(2-C5H4N)NH gives Ph(2-C5H4N)NAlMe2 and this reacts with MeLi in thf to yield the simple 'ate complex Ph(2-C5H4N)NAlMe3Li.thf, the employment of an organolithium substrate capable of beta-hydride elimination redirects the reaction significantly. Whereas the use of ButLi has previously yielded a main group interstitial hydride in which H- exhibits micro6-coordination, it is shown here that variability in the coordination sphere of the encapsulated hydride may be induced by manipulation of the organic ligand. Reaction of (c-C6H11)(2-C5H4N)NH with Me3Al/ButLi yields [{(c-C6H11)(2-C5H4N)N}6HLi8]+[(But2AlMe2)2Li]-, which is best viewed as incorporating only linear di-coordination of the hydride ion. The guanidine 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (hppH) in conjunction with Me2Zn/ButLi yields the micro8-hydride [(hpp)6HLi8]+[But3Zn]-.0.5PhMe. Formation of the micro8-hydride [(hpp)6HLi8]+[ButBEt3]- is revealed by employment of the system Et3B/ButLi. A new and potentially versatile route to interstitial hydrides of this class is revealed by synthesis of the mixed borohydride-lithium hydride species [(hpp)6HLi8]+[Et3BH]- and [(hpp)6HLi8]+[(Et3B)2H]- through the direct combination of hppLi with Et3BHLi.
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, UK CB2 1EW.
authors.forename: Sally R
authors.initials: SR
authors.lastname: Boss
authors.forename: Martyn P
authors.initials: MP
authors.lastname: Coles
authors.forename: Vicki
authors.initials: V
authors.lastname: Eyre-Brook
authors.forename: Felipe
authors.initials: F
authors.lastname: García
authors.forename: Robert
authors.initials: R
authors.lastname: Haigh
authors.forename: Peter B
authors.initials: PB
authors.lastname: Hitchcock
authors.forename: Mary
authors.initials: M
authors.lastname: McPartlin
authors.forename: James V
authors.initials: JV
authors.lastname: Morey
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Naka
authors.forename: Paul R
authors.initials: PR
authors.lastname: Raithby
authors.forename: Hazel A
authors.initials: HA
authors.lastname: Sparkes
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Tate
authors.forename: Andrew E H
authors.initials: AE
authors.lastname: Wheatley