Synthesis, Characterization, and Chiral Properties of Co^III₂Ag^I₃ Pentanuclear, Co^III₄Zn^II₄ Octanuclear, and Co^III Mononuclear Complexes with Aza-Capped Hexadentate-N₃S₃ Thiolate Ligands:  Crystal Structures of [Ag₃{Co(L)}₂][PF₆]₃ and [Zn₄O{Co(L)}₄][PF₆]₆ (L = N(CH₂NHCH₂CH₂

Abstract

The reaction of an S-bridged Co2(III)Ag3(I) pentanuclear complex, [Ag3[Co(aet)3]2][BF4]3 (aet = NH2CH2CH2S-), with paraformaldehyde in basic acetonitrile, followed by adding aqueous ammonia, produced an aza-capped Co2(III)-Ag3(I) complex, [Ag3[Co(L)]2]3+ ([1]3+) (L = N(CH2NHCH2CH2S-)3). The crystal structure of [1]3+ was determined by X-ray crystallography. [1][PF6]3 x H2O, empirical formula C18H44Ag3Co2F18N8OP3S6, crystallizes in the tetragonal space group 142m with a = 13.012(1) A, c = 24.707(2) A, and Z = 4. In [1]3+ the two aza-capped [Co(L)] units are linked by three Ag(I) atoms, such that the two Co(III) atoms are encapsulated in a macrobicyclic metallocage, [Ag3(I)(L)2]3-. [1]3+ was converted to an aza-capped Co4(III)Zn4(II) octanuclear complex, [Zn4O[Co(L)]4]6+ ([2]6+), by reaction with I- in the presence of Zn2+ and ZnO in water. The crystal structure of [2]6+ was also determined by X-ray crystallography. [2][PF6]6 x 8H2O, empirical formula C36H100Co4F36N16O9P6S12Zn4, crystallizes in the monoclinic space group P2(1/n) with a = 14.33(7) A, b = 25.67(10) A, c = 24.83(6) A, beta = 101.3(3) degrees , and Z = 4. In [2]6+ each of four [Co(L)] units is bound to each trigonal Zn3(II) face of the tetrahedral [Zn4(II)O]6+ core, such that each Co(III) atom is encapsulated in a macrobicyclic [Zn4(II)O(L)] fragment. Treatment of [2]6+ with a basic aqueous solution resulted in a cleavage of the Zn-S bonds to produce an aza-capped Co(III) mononuclear complex, [Co(L)] ([3]), from which [1]3+ is readily reproduced by the reaction with Ag+ in water. All the reactions were found to proceed with retention of the absolute configuration (delta or lambda) of the Co(III) chiral centers; deltadelta-[1]3+, deltadeltadeltadelta-[2]6+, and A-[3] were derived from deltadelta-[Ag3[Co(aet)3]2]3+. The contributions to circular dichroism (CD) from the triple helicity in [1]3+, besides from the asymmetric N and S donor atoms and the Co(III) chiral centers in [1]3+ and [2]6+, were estimated by comparing the CD spectra of deltadelta-[1]3+, deltadeltadeltadelta-[2]6+, and delta-[3].

Synthesis, Characterization, and Chiral Behavior of S-Bridged CoIIIPtIICoIII Trinuclear Complexes Composed of Bis(thiolato)-Type Octahedral Units cis(S)-[Co(aet)2(en)]+ and/or trans(N)-[Co(d-pen- N,O,S)2]- (aet = 2-Aminoethanethiolate, d-pen = d-Penicillaminate)

“…Certain thiolato groups coordinated to one Co III ion tend to bind with another metal ion to form S-bridged polynuclear structures, owing to the high nucleophilic character. − Utilizing this property, a large number of S-bridged polynuclear complexes composed of [Co(thiolato- S ) 3 (amine- N ) 3 ]-type octahedral units have been prepared by the reactions of fac ( S )-[Co(aet) 3 ] (aet = 2-aminoethanethiolate) or fac ( S )-[Co( l -cys- N , S ) 3 ] 3- ( l -cys = l -cysteinate) with a variety of metal ions. − On the other hand, S-bridged polynuclear complexes composed of [Co(thiolato- S ) 2 (amine- N ) 4 ] + -type units have remained largely unexplored, mainly because of the difficulty in isolation of this type mononuclear species, − and thus the key to control their structures and chiral properties has not been clarified.…”

Synthesis and crystallographic characterization of a mononuclear cobalt(III) complex possessing both thiolate and thioether donors: reactivity of an thiolate-bridged pentanuclear Co2Ag3 complex with iodomethane

“…In the course of our continuing study of the alkylation reaction of metal complexes with aminothiolate ligands (Okamoto et al, 1999;Chikamoto et al, 2005Chikamoto et al, , 2007Yoshinari & Konno, 2008, 2009, we herein report that an S-bridged Ag I 3 Co III 2 pentanuclear complex, {Ag 3 [Co(L)] 2 } 3+ [L 3-= N(CH 2 NHCH 2 CH 2 S À ) 3 ] (Tokuda et al, 2000), in which two tris(thiolate)-type octahedrally shaped Co III moieties with an aet derivative ligand, [Co(L)], are linearly linked by three Ag I ions, reacts with iodomethane to give a mono(thiolate)bis(thioether)-type complex, [Co(LMe 2 )] 2+ [LMe 2 À = N(CH 2 NHCH 2 CH 2 S À )(CH 2 NHCH 2 CH 2 SCH 3 ) 2 ]. It is noteworthy that the complex was crystallized as a hexafluoridophosphate salt, [Co(LMe 2 )](PF 6 ) 2 , and its molecular structure was fully determined by single-crystal X-ray diffraction analysis.…”

A Silver-Linked Supramolecular Cluster Encapsulating a Cesium Cation

“…The use of judiciously designed hybrid ligands to form supramolecular assemblies through coordination of two types of metal cations having incommensurate symmetry requirements has been successfully demonstrated by us as well as others. − We have recently reported pentametallic mixed-metal clusters derived from 4-(diphenylphosphino)benzene-1,2-diol (H 2 L ) which can chelate a hard cation through its phenolic oxygens while simultaneously binding a soft metal using its neutral phosphine site. , Hard metals such as Fe(III), Ga(III), Ti(IV), and Sn(IV) readily form anionic tris-chelates of the type M L 3 n - (M = Fe, Ga, n = 3; M = Ti, Sn, n = 2) which can serve as precursors to anionic clusters of the type M 2 M‘ 3 L 6 where M‘ is a soft metal such as Pd(II), Cr(0), Mo(0), and W(0) coordinated to the free phosphine of L (Scheme ). Formation of these C 3 h -symmetric mesocates is dependent on alkali metal counterions which are incorporated into deep molecular clefts and coordinated to endo -catecholate oxygens.…”