By following a new synthetic approach, which is based on the in situ formation of a basic medium by the reaction between the strong base Sb(V)S4 (3-) and the weak acid H2 O, it was possible to prepare three layered thioantimonate(III) compounds of composition [TM(2,2'-bipyridine)3 ][Sb6 S10 ] (TM=Ni, Fe) and [Ni(4,4'-dimethyl-2,2'-bipyridine)3 ][Sb6 S10 ] under hydrothermal conditions featuring two different thioantimonate(III) network topologies. The antimony source, Na3 SbS4 ⋅ 9 H2 O, undergoes several decomposition reactions and produces the Sb(III) S3 species, which condenses to generate the layered anion. The application of transition-metal complexes avoids crystallization of dense phases. The reactions are very fast compared to conventional hydrothermal/solvothermal syntheses and are much less sensitive to changes of the reaction parameters.
The new compound [Mn2(bipy)4SbS4](ClO4) was prepared by a new synthetic route for the preparation of thioantimonates(V) that can be used even at room temperature. Mixing aqueous solutions of [Mn(bipy)3](ClO4)2 and Na3SbS4 · 9H2O leads to immediate crystallization of the pure compound. In the structure an SbS43– anion acts as a tetradentate bridge connecting two Mn2+ cations of [Mn(bipy)3]2+ complexes (bipy = 2,2′-bipyridine). The compound features a hitherto unknown [Mn2(bipy)4SbS4]+ cation. Bipy ligands of adjacent cations are arranged parallel to each other leading to weak off-center parallel π-π interactions stabilizing the crystals. Magnetic measurements indicate weak antiferromagnetic exchange interactions between the Mn2+ centers.
The
reaction of an aqueous solution of Na3SbS3 with
[Ni(terpy)2]2+ (terpy = 2,2′:6′,2″-terpyridine)
afforded crystallization of three new thioantimonates in short reaction
times. Two polymorphic compounds, [Ni(terpy)2][Sb4S7]·H2O (1, 2), were obtained simultaneously under identical reaction
conditions, while an increase of the reaction temperature led to formation
of the third compound [Ni(terpy)2]2[Sb10S17] (3). In 1 the anion
consists of a [Sb4S7]2– chain,
whereas 2 is composed of a layered [Sb4S7]2– anion. Form 2 disappeared
at longer reaction times, and therefore modification 1 might represent the thermodynamically stable form at this temperature
despite the lower density compared to 2. Storing modification 1 at elevated temperatures the water can partly be removed
in a topotactic reaction leading to the compound [Ni(terpy)2][Sb4S7]·0.25 H2O (1A). Compound 3 exhibits a unique Sb:S
ratio, and a never before observed network topology significantly
enhancing the structural diversity of thioantimonates(III).
In the title compound, [Ni(C15H11N3)2](ClO4)2·0.5H2O, the Ni2+cation is coordinated by two terpyridine ligands to form a discrete complex and the coordination polyhedron can be described as a slightly distorted octahedron. It crystallizes as a hemihydrate with two perchlorate anions to compensate the charges. In the crystal, one of the two crystallographically independent perchlorate anions is involved in O—H...O hydrogen bonding to the water molecules, where two inversion-related water molecules link two inversion-related perchlorate anions into a ring with anR42(12) loop. The O-atom position of the water molecule is only half occupied,i.e.only half of the anions are involved in hydrogen bonding. A similar arrangement of two anions is also observed for the second crystallographically independent perchlorate anion but no water molecules are located between the anions. The cationic complex and the perchlorate anions are additionally linked by a number of weak C—H...O hydrogen bonds, forming a three-dimensional supramolecular structure. The crystal structure of the monohydrate of the same complex has been reported [Bakeret al.(1995).Aust. J. Chem.48, 1373–1378].
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