A niobium-necked cluster [As3Nb(As3Sn3)]3− with aromatic Sn32− 1. Issue 9 (1st February 2016) - Pan, Fu-Xing
Abstract : A new Zintl cluster [As3 Nb(As3 Sn3 )] 3− was synthesized and characterized, in which an As3 triangle and a bowl-type As3 Sn3 ligand are bridged by a niobium atom. The Sn3 ring is found to have σ-aromaticity featured by a delocalized Sn–Sn–Sn σ orbital. Abstract : We describe here the synthesis and characterization of a ternary cluster compound [As3 Nb(As3 Sn3 )] 3− (1 ), in which a niobium(v ) atom is coordinated by an As3 3− triangle and a bowl-type As3 Sn3 5− ligand. Cluster1 was synthesized by dissolving K8 NbSnAs5 (2 ) in the presence of [2.2.2]crypt in ethylenediamine solution, filtered and layered with toluene, then crystallized in the form of [K([2.2.2]crypt)]3 [As3 Nb(As3 Sn3 )]·en·tol. The flower-vase shaped compound1 features a new structure type, rather different from the known Zintl phases. The stability and bonding of1 are elucidated via extensive bonding analyses. The Sn3 ring is found to have σ-aromaticity featuring a delocalized Sn–Sn–Sn σ bond. Electronic structure calculations confirm the Nb(v ) oxidation state and weak Nb–Sn and Sn–Sn bonding, in addition to the normal Nb–As and As–As bonds.