Preparation, Characterization, and Some Properties of a T-Cage-Type S-Bridged RhIII4ZnII3 Heptanuclear Complex with a Defective [Zn3HO]5+ Core. Crystal Structure of Spontaneously Resolved [{Rh(aet)3}4Zn3HO]Br5 (aet = 2-Aminoethanethiolate)

Abstract

Abstract The reaction of fac(S)-[Rh(aet)3] with ZnBr2 in water produced a T-cage-type S-bridged polynuclear complex with a “defective” [Zn3HO]5+ core, [{Rh(aet)3}4Zn3HO]Br5 (1Br5), which was subject to spontaneous resolution to give and isomers. 1 was also optically resolved into the two isomers with use of [Sb2(R,R-tartrate)2]2−. The crystal structure and absolute configuration for the spontaneously resolved isomer were determined by X-ray crystallography. [{Rh(C2H6NS)3}4Zn3HO]Br5·9H2O, crystallizes in the cubic space group P213 with a = 19.186 (1) Å, V = 7062.1 (4) Å3, Z = 4, and R = 0.0648. In 1 the four octahedral fac(S)-[Rh(aet)3] subunits are bound to a quasi-tetrahedral [Zn3HO]5+ core in a tetrahedral arrangement. The chiral configurations are regulated to Δ for all fac(S)-[Rh(aet)3] subunits and R for all asymmetric bridging sulfur atoms in -1, giving a quasi-T symmetrical structure. 1 is unstable in water and convertible to a T-cage-type octanuclear complex with a “complete” [Zn4O]6+ core, [{Rh(aet)3}4Zn4O]6+ (2), and to a linear-type S-bridged trinuclear complex, [Co{Rh(aet)3}2]3+, by adding ZnBr2 and [CoCl(NH3)5]Cl2, respectively. The electronic absorption and circular dichroism (CD) spectral behavior of 1 are discussed in comparison with those of 2.