title: Straightforward route to the adamantane clusters [Sn4Q10]4- (Q = S, Se, Te) and use in the assembly of open-framework chalcogenides (Me4N)2M[Sn4Se10] (M = Mn(II), Fe(II), Co(II), Zn(II)) including the first telluride member (Me4N)2Mn[Ge4Te10].
abstract: The reaction of K(2)Sn(2)Q(5) (Q = S, Se, Te) with stoichiometric amounts of alkyl-ammonium bromides R(4)NBr (R = methyl or ethyl) in ethylenediamine (en) afforded the corresponding salts (R(4)N)(4)[Sn(4)Q(10)] (Q = S, Se, Te) in high yield. Although the compound K(2)Sn(2)Te(5) is not known, this reaction is also applicable to solids with a nominal composition "K(2)Sn(2)Te(5)" which in the presence of R(4)NBr in en are quantitatively converted to the salts (R(4)N)(4)[Sn(4)Te(10)] on a multigram scale. These salts contain the molecular adamantane clusters [Sn(4)Q(10)](4-) and can serve as soluble precursors in simple metathesis reactions with transition metal salts to synthesize the large family of open-framework compounds (Me(4)N)(2)M[Sn(4)Se(10)] (M = Mn(2+), Fe(2+), Co(2+), Zn(2+)). Full structural characterization of these materials as well as their magnetic and optical properties is reported. Depending on the transition metal in (Me(4)N)(2)M[Sn(4)Se(10)], the energy band gaps of these compounds lie in the range of 1.27-2.23 eV. (Me(4)N)(2)Mn[Ge(4)Te(10)] is the first telluride analogue to be reported in this family. This material is a narrow band gap semiconductor with an optical absorption energy of 0.69 eV. Ab initio electronic band structure calculations validate the semiconductor nature of these chalcogenides and indicate a nearly direct band gap.
authors.affiliation: Department of Chemistry, University of Crete, Voutes 71003, Heraklion, Greece.
authors.forename: Konstantina
authors.initials: K
authors.lastname: Tsamourtzi
authors.forename: Jung-Hwan
authors.initials: JH
authors.lastname: Song
authors.forename: Thomas
authors.initials: T
authors.lastname: Bakas
authors.forename: Arthur J
authors.initials: AJ
authors.lastname: Freeman
authors.forename: Pantelis N
authors.initials: PN
authors.lastname: Trikalitis
authors.forename: Mercouri G
authors.initials: MG
authors.lastname: Kanatzidis