Structurally Precise Silver Sulfide Nanoclusters Protected by Rhodium(III) Octahedra with Aminothiolates

Abstract

A 60‐nuclear silver sulfide nanocluster with a highly positive charge (1) has been synthesized by mixing an octahedral RhIII complex with 2‐aminoethanethiolate ligands, silver(I) nitrate, and d‐penicillamine in water under mild conditions. The spherical surface of 1 is protected by the chiral octahedral RhIII complex, with cleavage of the C−S bond of the d‐penicillamine supplying the sulfide ions. Although 1 does not contain d‐penicillamine, it is optically active because of the enantiomeric excess of the RhIII molecules induced by chiral transfer from d‐penicillamine. 1 can accommodate/release external Ag+ ions and replace inner Ag+ ions by Cu+ ions. The study demonstrates that a thiolato metal complex and sulfur‐containing amino acid can be used as cluster‐surface‐protecting and sulfide‐supplying regents, respectively, for creating chiral, water‐soluble, structurally precise silver sulfide nanoclusters, the properties of which are tunable through the addition/removal/exchange of Ag+ ions.

Heterometallation of Photoluminescent Silver(I) Sulfide Nanoclusters Protected by Octahedral Iridium(III) Thiolates

“…We carried out the reaction of fac ‐[Ir(aet) 3 ] with three equiv. of AgBF 4 in water at 50 °C in the presence of d ‐H 2 pen according to the synthetic procedure for [Ag 46 S 13 {Rh(aet) 3 } 14 ] 20+ ([ 1’ ] 20+ ) [10] . The reaction caused a gradual color change from light yellow to dark red, showing visible absorption at approximately 520 nm.…”

“…In terms of the chirality, the Δ and Λ configurational fac ‐[Ir(aet) 3 ] octahedra are alternately arranged in the [Ag 12 {Ir(aet) 3 } 12 ] 12+ belt in the Δ 6 Λ 6 meso form, whereas the Δ and Λ configurational fac ‐[Ir(aet) 3 ] octahedra exist at the apical positions to give the ΔΛ meso form. Thus, trigonal‐[ 1 ](NO 3 ) 20 contains [ 1 ] 20+ cations with the Δ 7 Λ 7 configuration, as in the case of trigonal‐[ 1’ ](NO 3 ) 20 [10] …”

“…The absorption spectrum of [ 1 ](NO 3 ) 20 in water exhibits an intense visible band (ϵ=2.52×10 4 M −1 cm −1 ) at approximately 520 nm (Figure 2, Table S1), [18] which is assignable to the charge transfer (CT) transition from the 3p (S) orbital to the 5s (Ag) orbital [10,23,24] . Since the overall spectral feature of [ 1 ](NO 3 ) 20 is very similar to that of [ 1’ ](NO 3 ) 20 , the transition is hardly affected by the protecting fac ‐[M(aet) 3 ] (M=Rh III , Ir III ) molecules [10] …”

“…We assume that the preference of a linear coordination geometry for Cu I and Au I leads to the unique site‐specific heterometallation in [ 1 Cu ] 20+ and [ 1 Au ] 20+ to maintain the overall nanocluster covered by the fac ‐[Ir(aet) 3 ] metalloligands. It should be noted that these are very rare heterometallic sulfide nanoclusters with ordered heteroatoms in a definite composition [9b–d,10] …”

“…In the course of our long‐standing study on the creation of heterometallic coordination compounds by using thiolato metal complexes as S‐donating metalloligands, [11–15] we have recently found that the reaction of fac ‐[Rh(aet) 3 ] (aet=2‐aminoethanethiolate) with Ag + in water in the presence of d ‐penicillamine ( d ‐H 2 pen) generates a unique silver(I) sulfide nanocluster protected by fac ‐[Rh(aet) 3 ] metalloligands, [Ag 46 S 13 {Rh(aet) 3 } 14 ] 20+ ([ 1’ ] 20+ ); this reaction is accompanied by the desulfurization of d ‐penicillamine [10] . Due to its structural robustness, the Rh III 14 Ag I 46 60‐nuclear cluster underwent a site‐specific metal exchange of its tetrahedral Ag I 4 S core by Cu I to form the isostructural [Ag 43 Cu 3 S 13 {Rh(aet) 3 } 14 ] 20+ .…”