Synthesis, characterization and some properties of S-bridged polynuclear complexes composed of fac(S)-[Cr(aet) 3] units (aet=2-aminoethanethiolate (aet). Crystal structures of [Ni{Cr(aet) 3} 2] 2+ and [{Cr(aet) 3} 4Zn 4O] 6+

Abstract

The reactions of newly prepared fac(S)-[Cr(aet) 3] ( 1) with Zn 2+ and Ni 2+ gave the polynuclear complexes [{Cr(aet) 3} 4Zn 4O] 6+ ( 2) and [Ni{Cr(aet) 3} 2] 2+ ( 3), respectively, where aet denotes 2-aminoethanethiolate (NH 2CH 2CH 2S –). The structures of complex cations 2 and 3 are determined by the X-ray diffractions. 2Br 6·6H 2O is spontaneously resolved as single crystals and crystallizes in the cubic space group P2 13, a=19.024(1) Å, Z=4, and R=0.044. 3(NO 3) 2·2H 2O crystallizes in the triclinic space group P1̄ with a=10.228(2), b=12.265(3), c=13.362(3) Å, α=101.08(1), β=108.02(1), γ=102.35(1)°, Z=2, and R=0.031. 2 consists of four fac(S)-[Cr(aet) 3] units, four Zn atoms, and one central μ 4-oxygen atom, forming the T-cage-type octanuclear structure. 3 consists of two fac(S)-[Cr(aet) 3] units and one Ni atom, forming linear-type trinuclear structure. The electronic absorption and CD spectral behavior of the isolated complexes are discussed in comparison with those of the corresponding polynuclear complexes. The effective magnetic moments are 3.99 μ B for 1 at 296 K, and 7.58 μ B for 2, and 5.19 μ B for 3 at 300 K. 3 indicates the presence of intramolecular antiferromagnetic exchange interactions, but 2 does not show the intramolecular magnetic exchange interactions.