Diverse Tp*-Capped W–Cu–S Clusters from One-Pot Assembly Involving in Situ Thiolation of Phosphines

Abstract

In the absence/presence of S8, the one-pot assembly of [Et4N][Tp*WS3] [1; Tp* = hydridotris(3,5-dimethylpyrazol-1-yl)borate] with [Cu(MeCN)4]PF6 and bis- or tetraphosphine ligands 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,4-bis(diphenylphosphino)butane (dppb), and N,N,N',N'-tetrakis(diphenylphosphinomethyl)ethylenediamine (dppeda) produces six W-Cu-S clusters, namely, [(Tp*WS3Cu2Cl)2(dppe)] (2), [Tp*WS3Cu4(dppp)2(μ4-Cl)(μ-Cl)]PF6·MeCN (3·MeCN), [(Tp*WS3Cu3)2(μ4-Cl)(μ-Cl)2(dpppS2)] (4), [(Tp*WS3Cu2Cl)2(dppbS2)]·2MeCN·2H2O (5·2MeCN·2H2O), [(Tp*WS3Cu3Cl2)2(dppbS2)] (6), and [(Tp*WS3Cu3)2(Ph2PS2)3(μ6-Cl)0.5](PF6)0.5·0.75CH2Cl2 (7·0.75CH2Cl2). Compounds 2-7 are characterized by elemental analysis, IR, UV-vis, (1)H and (31)P{(1)H} NMR, electrospray ionization mass spectrometry, and X-ray crystallography. For 2, the dppe ligand bridges a pair of butterfly-shaped [Tp*WS3Cu2] cores to form a double-butterfly-shaped structure. For 4, the dppp ligand is susceptible toward S association and forms an in situ generated dpppS2 ligand, supporting an octanuclear double-half-open-cubane structure and contrasting an analogous system wherein a pentanuclear motorcycle-shaped cationic cluster 3 is formed with the absence of S8. A longer dppb ligand readily converts to S-based ligands in 5 and 6, subsequently serving as bridges between a pair of a butterfly-shaped (5) and nest-shaped (6) clusters. Further use of a tetraphosphine ligand, dppeda, in the cluster formation, with the presence of S8, leads to an unexpected ligand degradation to give the [Ph2PS2](-) anions. Three [Ph2PS2](-) anions juxtapose a pair of nest-shaped cluster cores to yield an octanuclear cluster, 7, featuring a cage to encapsulate μ6-Cl(-). The third-order nonlinear-optical (NLO) properties of 2-7 in N,N-dimethylformamide, investigated using a Z-scan technique at 532 nm, show that 2-6 have a reverse saturable absorption, while 7 has a notable saturable absorption. All of 2-7 exhibit a self-focusing effect with hyperpolarizability γ values in the range of 4.71 × 10(-30)-1.02 × 10(-29) esu, which are 440-1000 times higher than that of 1. The formation of 4-7 from 1 through the in situ thiolation of phosphine ligands presents a new approach to the design and assembly of the W-Cu-S clusters with interesting structural arrays and better NLO properties.

Butterfly and Nest‐Shaped Tp*‐W‐Cu‐S Cluster Monomers and Dimers with Hexamethylenetetramine as Ligand: Anion‐Dependent Structures and Nonlinear Optical Properties

“…[ 47 ] It is also higher than those found in known W/Cu/S clusters derived from 1 (Table 1), e.g ., [Tp*WS 3 Cu 2 (bipy) 1.5 ](PF 6 ) (3.2 × 10 −31 esu), [ 42 ] K[Tp*WS 3 Cu 3 (DMF){Cu 2 (CN) 4.5 }] 2 (4.39 × 10 −31 esu) (DMF = N , N ‐dimethylformamide), [ 3 ] [Tp*WS 3 Cu 3 (DMF)(CN) 3 Cu] (4.36 × 10 −31 esu), [ 32 ] and [Tp*WS 3 Cu 2 (bdppmapy)](PF 6 ) (2.43 × 10 −31 esu) (bdppmapy = N , N ‐ bi‐(diphenylphosphanylmethyl)‐2‐aminopyridine). [ 48 ] These values are similar to those of [(Tp*WS 3 Cu 2 Cl) 2 (dppe)] (4.71 × 10 −30 esu; dppe = 1,2‐bis‐(diphenylphosphino)ethane) [ 18 ] and [Tp*WS 3 Cu 2 (CN) 2 Cu](pz) 0.5 (3.69 × 10 −30 esu; pz = pyrazine). [ 16 ] They are slightly lower than those of [(Cp*MoS 3 Cu 3 ) 2 (bpe) 2 Br 4 ] (4.29 × 10 −29 esu; bpe = 1,2‐bis(4‐pyridyl)ethane) [ 8 ] and [Cp*MoS 3 Cu 3 (pyz)(NCS) 2 ] (2.96 × 10 −29 esu; pyz = 1,4‐pyrazine).…”

“…Other experimental conditions for these NLO measurements were the same as described in our previous articles. [ 18,20,51 ]…”

“…Transition metal clusters of organo‐thiometallates such as [Cp*MS 3 ] − (Cp* = pentamethylcyclopentadienyl; M = Mo, W), [ 1 ] [TpMoS(S 4 )] − , [Tp*MoS(S 4 )] − , [TpWS 3 ] − and [Tp*WS 3 ] − (Tp = hydridotris(pyrazol‐1‐yl)borate; Tp* = hydridotris(3,5‐dimethylpyrazol‐ 1‐yl)borate) [ 2 ] have been extensively investigated in the last two decades because of their diverse structural characteristics, [ 3‐9 ] their revelation to biological systems, [ 10‐13 ] catalysis, [ 14‐15 ] and optoelectronic materials. [ 3,16‐24 ] In this regard, we and others have developed a keen interest in the development of molecular arrays from preformed Mo(W)‐Cu(Ag)‐S clusters. [ 25‐29 ] Some of these molecular entities are capable of gas adsorption, [ 30 ] sensing, [ 31 ] or exhibit nonlinear optical properties.…”

“…[ 25‐29 ] Some of these molecular entities are capable of gas adsorption, [ 30 ] sensing, [ 31 ] or exhibit nonlinear optical properties. [ 17‐19,21,30,32‐37 ] We have further investigated a diverse array of molecular entities using rigid/flexible ditopic ( e.g ., 4,4’‐bipyridine, bipy), [ 19 ] tritopic ( e.g ., 2,4,6‐tri(4‐ pyridyl)‐1,3,5‐triazine, tpt), [ 7,19,38 ] and tetratopic N ‐based ligands ( e.g ., 5,10,15,20‐tetra(4‐pyridyl)‐21 H ,23 H ‐porphyrin, H 2 tpyp), [ 7 ] wherein these N sites are co‐planar. Further introducing a tetratopic ligand with four N sites spatially arranged in a tetrahedral manner is expected to yield high‐dimensional networks of interest.…”

Investigation of the Effect of a Mixed-Ligand on the Accommodation of a Templating Molecule into the Structure of High-Nucleus Silver Clusters

“…Rare examples adopt a μ 3 :O 1 ,O 2 bridging fashion . Four diphenylphosphinates on clusters 1 and 2 uniquely exhibit the distinct μ 5 :O 2 ,O 3 binding mode, which is also never observed for the dichalcogenophosphinate ligands. − …”