Rational creation of chiral multinuclear and metallosupramolecular compounds from thiol-containing amino acids

Abstract

Developments in the rational creation of chiral multinuclear and metallosupramolecular compounds based on linear-type metal complexes with penicillaminate (pen), as well as their functionality as a multidentate chiral metalloligand, is the main subject of this paper. The reactions of a mononuclear Au(I) complex, [Au(d-pen)(2)](3-), in which two d-pen ligands bind to an Au(I) center through thiolato S atoms, with transition metal ions afford a variety of S-bridged heterobimetallic multinuclear complexes, the structures and properties of which are highly dependent on the nature of reacting metal ions. The created multinuclear complexes still act as a metalloligand when they possess free amine and/or carboxylate groups, leading to the formation of heterotrimetallic supramolecular structures by reacting with third metal ions. While the Au-S bonds in [Au(d-pen)(2)](3-) are generally retained in the course of the reactions with metal ions, this is not the case for the Hg-S bonds in the corresponding Hg(II) complex, [Hg(d-pen)(2)](2-). A remarkable chiral behavior of multinuclear complexes composed of [Au(l-cys)(2)](3-) (cys = cysteinate), which is opposite to that composed of [Au(l-pen)(2)](3-), is also presented.

Dielectric Jump and Negative Electrostriction in Metallosupramolecular Ionic Crystals

“…It has been recognized that a variety of polynuclear and supramolecular coordination compounds are created from thiol-containing amino acids, such as l -cysteine ( l -H 2 cys), d -penicillamine ( d -H 2 pen), and their derivatives, in combination with 3d and 4d transition metal ions, because these amino acids can adopt various coordination modes to multiple metal centres by using amine, carboxyl, and/or thiol groups dependent on their protonation/deprotonation states 1–4 . We found that the introduction of hydrophobic dppe (1,2-bis(diphenylphosphino)ethane) into a gold(I)-cobalt(III) coordination system with hydrophilic d -pen affords a cationic Au I 4 Co III 2 hexanuclear complex, [Au 4 Co 2 (dppe) 2 ( d -pen) 4 ] 2+ ([ 1 ] 2+ ), in which two Co III centres are spanned by two [Au I 2 (dppe)( d -pen) 2 ] 2− linkers 1–3 .…”

Metallosupramolecular Structures Derived from a Series of Diphosphine-bridged Digold(I) Metalloligands with Terminald-Penicillamine

“…We found that [H 2 1 ] coordinates to divalent transition‐metal ions (M = Ni II , Zn II ) in a chelating manner, forming an S‐bridged Au 2 M trinuclear structure with an 8‐membered MAu 2 S 2 P 2 C metalloring, [M{Au 2 (dppm)( d ‐pen) 2 }] ([ 20 ] for M = Ni II , [ 21 ] for M = Zn II ) (Scheme ) 16,17. This is in sharp contrast to the coordination mode of [Au( d ‐pen‐ S ) 2 ] 3– , which uniformly adopts a bridging‐type mode 10,11…”

“…The trinuclear complexes [ 20 ] and [ 21 ] contain an octahedral [M( d ‐pen) 2 ] 2– unit that is bound to a [Au 2 (dppm)] 2+ moiety through S atoms. The M atom selectively adopts a distorted N 2 O 2 S 2 octahedral geometry with a trans (O) geometric configuration 10. The two bridging S atoms are asymmetric and have the R chiral configuration.…”

“…Complex [ 29 ] + consists of an octahedral [Co( d ‐pen) 2 ] – unit bounded by two {Au(PPh 3 )} + moieties through S atoms. Of the three geometrical configurations ( trans (N), trans (O), and trans (S)) possible for the [M( d ‐pen‐ N , O , S ) 2 ] n – octahedron,10 [ 29 ] + adopts the trans (O) configuration in the solid and solution states, as found in the dppe‐bridged cyclic hexanuclear complex [ 25 ] 2+ . This implies that the trans (O) configuration is the most thermodynamically stable for the [M( d ‐pen‐ N , O , S ) 2 ] – unit, bound by two {Au(PPh 2 R)} + moieties through S atoms.…”

“…During these investigations, we found that a mononuclear gold(I) complex with d ‐pen, [Au( d ‐pen‐ S ) 2 ] 3– ,15 in which a linear gold(I) ion is coordinated by two d ‐pens through S atoms, acts as a multidentate metalloligand using coordinated thiolato and non‐coordinated amine and carboxylate groups to form a variety of heterometallic structures responding to the reacting metal ions and reaction conditions 10,11. This result suggested that the monodentate‐ S coordination of the d ‐pen moiety is a key factor for the coordination versatility of the metalloligand.…”