Ag(I) Dithiocarbamate Clusters

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Ferrocene-Functionalized Cu(I)/Ag(I) Dithiocarbamate Clusters Pilli V. V. N. Kishore, Jian-Hong Liao, Hsing-Nan Hou, Yan-Ru Lin, and C. W. Liu* Department of Chemistry, National Dong Hwa University, Hualien, Taiwan 97401, R. O. C. S Supporting Information *

ABSTRACT: A series of compounds, namely, [Cu8(μ4-H){S2CNMeCH2Fc}6](PF6) (1), [Cu7(μ4-H) {S2CNiPrCH2Fc}6] (2), [Cu3{S2CN(Bz) (CH2Fc)}2(dppf)2](PF6) (3), and [Ag2{S2CNMe(CH2Fc)}2(PPh3)2] (4) (dppf = 1,1′-bis(diphenylphosphino)ferrocene), supported by multiferrocene assemblies, were synthesized. All the compounds were characterized by 1H NMR, Fourier transform infrared, elemental analysis, and electrospray ionization mass spectrometry techniques. Single-crystal X-ray structural analysis revealed that 1 is a monocationic octanuclear CuI cluster and that 2 is a neutral heptanuclear CuI cluster with tetracapped tetrahedral (1) and tricapped tetrahedral (2) geometries entrapped with an interstitial hydride, anchored by six ferrocene units at the periphery of the core. Compounds 3 and 4 comprise trimetallic CuI and dimetallic AgI cores enfolded by four and two ferrocene moieties. Interestingly both chelating and bridging modes of binding are observed for dppf ligand in 3. Further the formation and isolation of polyhydrido copper clusters [Cu28H15{S2CNiPrCH2Fc}12](PF6) (5) and [Cu28H15{S2CNnBu2}12](PF6) (7), stabilized by bulky ferrocenyl and n-butyl dithiocarbamate ligands, was demonstrated. They are readily identified by 2H NMR studies on their deuterium analogues, [Cu28D15{S2CNiPrCH2Fc}12](PF6) (6) and [Cu28D15{S2CNnBu2}12](PF6) (8). Though the structure details as well as spectroscopic characterizations of 5 are yet to be investigated, the compound 7 is fully characterized by variety of spectroscopy including single-crystal X-ray diffraction. The cyclic voltammetry studies for compounds 1, 2, and 4 display irreversible redox peaks for Fe2+/Fe3+ couple wherein the reduction peaks are not well-resolved due to some adsorption of the complex onto the electrode surface.

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also the majority of main group, f-block elements.13 Another interesting aspect of dithiocarbamate ligands is their ability to stabilize high formal oxidation states (e.g., iron(IV), copper(III), and nickel(IV)).14 We have previously reported the design, synthesis, and structural aspects of hydrido CuI clusters [Cu8HL6]+ and [Cu7HL6] [L = (E2PR2)−, (E2CNR2)−; E = S, Se] with tetracapped tetrahedral and tricapped tetrahedral core geometries supported by dithiocarbamate/phosph(in)ate ligands.15 Interestingly the oxidative release of entrapped hydride in the [Cu8H(L)6]+/[Cu7HL6] cores via the reaction of (NH4)2[Ce(NO3)6] has been demonstrated.15c Our recent contributions to this chemistry have led to path-breaking results when these core-containing structures are further reacted with excess borohydrides. To our uttermost surprise, fascinating nanoscopic copper hydrides [Cu28(H)15(S2CNnPr2)12](PF6),16 [Cu20H11{E2P(OiPr)2}9] (E = S, Se),17 and [Cu32(H)20{S2P(OiPr)2}12]18 are stabilized, and these results open new avenues in hydrogen storage materials. We are particularly interested in extending this chemistry by utilizing frameworks of both [Cu8HL6]+ and [Cu7HL6] as excellent platforms for generating multiferrocene architectures. With this in mind we try to explore molecular assemblies comprising similar core structures supported by dithiocarbamate ligands, which can be functionalized at their backbone with redox-active ferrocenes, so that different applications and interactions can be studied.

INTRODUCTION Functionalization of macromolecules/nanoparticles with redoxactive ferrocenes on their periphery is currently a very active area of research owing to the potential applications of these systems in the fields of optics and electronics.1 The different strategies used for fabricating multiferrocene assemblies include aromatics,2 polymers,3 and surface of metal nanoparticles.4 Stang et al. adopted coordination driven self-assembly approach for the preparation of nanoscopic supramolecular ferrocene assemblies with predetermined shapes, sizes, and geometries.5 Frequently multiferrocene assemblies have been reported as metallodendrimers where a central benzene-type aromatic core was constructed and ferrocene units were grafted at the peripheries either by convergent (from the core of the molecule to its periphery) or divergent (from the periphery to the core) methods.6 Because of its large surface area-to-volume ratio the metallodendrimers can incorporate more ferrocene units, but dendrimers require multistep syntheses, tedious synthetic efforts that often lead to end products with poor yield. Nevertheless, inorganic cores, for example, stannoxanes,7 cyclophosphazenes,8 aluminum−nitrogen/carbide frameworks,9 metal chalcogenolates,10 multinuclear transition and lanthanide metal cores,11 overcome these challenges and serve as potential candidates for supporting multiferrocene assemblies. Recently the synthesis of ferrocene assemblies via click chemistry (CuAAC) has been reported.12 However, dithiocarbamates are extremely versatile ligands that form stable complexes with all the transition elements and © XXXX American Chemical Society

Received: January 28, 2016

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DOI: 10.1021/acs.inorgchem.6b00201 Inorg. Chem. XXXX, XXX, XXX−XXX

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Inorganic Chemistry Chart 1

CH2Fc}6] (2) [Cu3{S2CN(Bz)(CH2Fc)}2(dppf)2](PF6) (3) [Ag(PPh 3 )(S 2 CNMeCH 2 Fc)] 2 (4) [Cu 28 H 15 {S 2 CN i PrCH2Fc}12](PF6) (5) [Cu28D15{S2CNiPrCH2Fc}12](PF6) (6) [Cu 2 8 H 1 5 {S 2 CN n Bu 2 } 1 2 ](PF 6 ) (7), and [Cu 2 8 D 1 5 {S2CNnBu2}12](PF6) (8) are presented, where the compounds (5 and 6) are unstable, the rest are stable. Further the redox chemistry of the clusters (1, 2, and 4) was examined by cyclic voltammetry.

Surprisingly this kind of system has not been investigated extensively;19 however, there are some reports on transition metal complexes with ferrocene-functionalized dithiocarbamate ligands used as sensitizers for light-harvesting reactions.19a,b Interestingly the coordination ability of other organometallic sulfur ligands toward CuI/AgI has also been explored.20 Our objective here is to functionalize the Cu8(μ4-H), Cu7(μ4-H) cores with redox-active ferrocenes, and our interest in this area stems from the possibility of using these cores as alternative frameworks for the stabilization of polyhydrido metal clusters supported by polyferrocenyl architectures in a manner similar to that shown in the aforementioned copper hydrides.16−18 Further we are also interested in the study of their redox behaviors. So herein self-assembly reactions of ferrocene-functionalized dithiocarbamate ligands {K(S2CNRCH2Fc)} [R = Me (1), iPr (2, 5, and 6), Fc = ferrocenyl]/{K(S2CNnBu2)} (7 and 8) with [Cu(CH3CN)4](PF6)/[Ag(CH3CN)4](PF6)(4) in the presence of hydride donor reagents [(Bu4N)(BH4)(1, 2), LiBH4· THF(5−8)] (THF = tetrahydrofuran) and phosphine-based ancillary ligands [(dppf(3), PPh3(4)] (dppf = 1,1′-bis(diphenylphosphino)ferrocene) were investigated. In this article, efforts and results obtained in the synthesis and structural charecterization (1−4 and 7) of [Cu8(μ4-H){S 2 CNMe(CH 2 Fc)} 6 ](PF 6 ) (1) [Cu 7 (μ 4 -H){S 2 CN( i Pr)-

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RESULTS AND DISCUSSION The synthetic methodology used is as follows: compounds 1 and 2 were synthesized by treating stoichiometric amounts of [Cu(CH3CN)4](PF6) with K(S2CNRCH2FC) [R = Me (1), iPr (2)] and (Bu4N)(BH4) in acetonitrile. Complexes 3 and 4 were obtained by reacting equimolar ratios of [M(CH3CN)4](PF6) [M = Cu (3), Ag (4)] with K(S2CNRCH2FC) [R = Ph (3), Me (4)] and dppf (3)/PPh3 (4) ligands in THF at ambient temperature (Chart 1). Compounds 6, 7, and 8 are synthesized by treating 2 equiv of [Cu(CH3CN)4](PF6) with 1 equiv of dithiocarbamate [(K(S2CNiPrCH2FC) (6), K(S2CNnBu2) (7, 8)] ligand in the presence of excess NaBD4 (6 and 8) and LiBH4·THF (7). Single crystals suitable for X-ray diffraction were grown from acetonitrile (1), chloroform/hexane (2, 4, and 7) and dichloromethane/hexane (3). Important crystallographic parameters are given in the Table 1. The compounds B


Article

Inorganic Chemistry Table 1. Crystallographic Data of Clusters 1−4 and 7 compound formula Fw crystal system space group a (Å) b (Å) c (Å) α (deg) β (deg) γ (deg) V (Å3) Z Dcalcd (g cm−3) μ (mm−1) T (K) θmax (deg) reflections collected/ unique (Rint) parameters/restraints R1,a wR2b [I > 2σ(I)] R1,a wR2b (all data) c goodness-of-fit a

1 C90H103Cu8F6Fe6N12PS12 2725.95 trigonal P3̅ 19.1030(7) 19.1030(7) 8.1014(3) 90 90 120 2560.3(2) 1 1.768 2.766 150(2) 25.00 11 754/3012 (0.0537)

2 C90H109Cu7Fe6N6S12 2439.43 triclinic P1̅ 12.7042(3) 13.3247(4) 15.4139(4) 78.8237(7) 83.5267(7) 70.8090(6) 2414.14(11) 1 1.678 2.684 296(2) 25.00 20 621/8457 (0.0185)

3 C109H95Cl9Cu3F6Fe4N2P5S4 2563.02 monoclinic P21/n 15.708(7) 34.184(15) 22.178(9) 90 110.188(11) 90 11177(8) 4 1.523 1.483 296(2) 25.00 32 587/19 546 (0.0489)

4 C62H58Ag2Fe2N2P2S4 1348.72 triclinic P1̅ 10.1901(4) 11.0874(4) 13.3699(6) 99.7200(10) 104.8110(10) 98.5690(10) 1409.83(10) 1 1.812 2.276 296(2) 25.00 12 729/4959 (0.0159)

7 C108H231Cu28F6N12PS24 4391.56 triclinic P1̅ 15.3196(11) 15.5413(11) 20.7294(15) 106.1630(10) 107.877(2) 94.706(2) 4435.1(6) 1 1.644 3.611 150(2) 25.00 39 468/15 553 (0.0183)

229/296 0.0452, 0.1100 0.0725, 0.1237 1.033

670/1086 0.0465, 0.1190 0.0576, 0.1271 1.045

1255/1758 0.0977, 0.2623 0.1461, 0.2972 1.058

334/0 0.0235, 0.0573 0.0281, 0.0602 1.021

904/221 0.0349, 0.0938 0.0411, 0.0975 1.080

R1 = ∑∥Fo| − |Fc∥/∑|Fo|. bwR2 = {∑[w(Fo2 − Fc2)2]/∑[w(F02)2]}1/2. cGOF = [∑w(Fo2 − Fc2)2/(nobs − nparam)]1/2.

closer to the previously reported metal complexes [(dppf){AuS2CN(CH2CHCH2)2}2] (30.1 ppm),21 [Ni{S2CN(CH2CHCH2)2}(dppf)]PF6 (31.1 ppm),22 and [Pt(dppf)(SCH2CH2CH2S)] (22.2 ppm)23 stabilized by dppf/dichalcogenide-based mixed ligand systems, clearly demonstrating that this behavior is strongly dependent on the ancillary ligands. Further this single peak at δ 23.27 ppm (Figure S4) suggests that the probability of interconverting chelating and bridging coordination modes of dppf on a trimetallic core is possible at room temperature (vide infra). As mentioned above the use of excess hydride source in the reaction results in the formation of polyhydrido copper(I) clusters [Cu28H15{S2CNiPrCH2Fc}12](PF6) (5) and [Cu28H15{S2CNnBu2}12]PF6 (7). Both compounds are confirmed by 2H NMR spectroscopy on their deuterium analogues, [Cu28D15{S2CNiPrCH2Fc}12](PF6) (6) and [Cu28D15{S2CNnBu2}12](PF6) (8), obtained from similar reactions with excess NaBD4. The 2H NMR peaks for both compounds are well-integrated for 15 deuterium atoms (Figure S6) with peak integral ratios of 8:1:6. The chemical shift values for 8 (−0.72, 1.31, 4.29 ppm) are closer to the previously reported [Cu28(D)15(S2CNnPr2)12](PF6) (−0.82, 1.38, 4.25 ppm), but the chemical shift values for 6 (−0.47, 1.74, 4.53 ppm) appear more downfield, which could be due to the electron-withdrawing nature of the ferrocene ligands. Further both 2H NMR spectroscopic studies and electrospray ionization (ESI) mass spectrometry analysis for 6 reveal that the compound is highly unstable and decomposes to [Cu7D(S2CNiPrCH2Fc)6], which is usually encountered as a byproduct in the cluster synthesis (Figures S7 and S8). The reasons accounting for the instability of 6 are either steric hindrance induced by bulky ferrocenyl groups or an uneven vibration offered by various unsymmetrical ferrocenyl ligands around the central core Cu28H15, which would possibly break the Cu−H bonds and destabilize an intact Cu28H15 core. However, this is in sharp contrast to [Cu28H15{S2CNnBu2}12](PF6) (7), where the rigid Cu28H15 core is strong enough to

were characterized by standard spectroscopic and analytical methods. The sharp bands in the IR region of 1449−1490 cm−1 can be attributed to the stretching vibrations of C−N group of N− CSS− moiety. Further the partial double-bond character of C− N group is supported by the appearance of characteristic medium-intensity absorption bands in the region of 1626−1664 cm−1 assigned to the C−N stretching mode. In addition, the stretching frequencies corresponding to C−S (−CSS), C−H are found in the region between 914−1085 cm−1 and 2924− 2963 cm−1, which are consistent with the literature reports.19 In the 1H NMR spectra of the complexes 1, 2, and 4 the cyclopentadienyl ring protons appear as a broad singlet in the region of 4.16−4.45 ppm, and in compound 3 these protons are observed as a multiplet in the region of 3.86−4.43 ppm. The signals observed around 5.11−5.30 ppm are assigned to the methylene protons directly attached to the cyclopentadienyl rings. The phenyl ring protons in compounds 3 and 4 appear as a multiplet between 7.32−7.82 ppm. The compounds 7 and 8 exhibit two multiplets and two triplets centered at 1.33, 1.80 ppm and 0.92, 3.98 ppm, respectively, corresponding to methylene and methyl protons of n-butyl group. Further 7 exhibits two broad singlet hydride resonances at −0.8 and 4.1 ppm with peak integral ratio of 8:6; unfortunately, one deeply buried hydride ion that is expected to come at ∼1.31 ppm was merged with chemical shift values (1.29−1.40 ppm) of n-butyl group protons. Nevertheless it was identified in 2H NMR on its deuterium analogue 8, which was discussed below. The slightly downfield 1H NMR values upon comparing to free ligands suggest metal (M) to ligand (S) bonding in the complexes. 31 1 P{ H} NMR spectra display a septet for a PF6 counteranion at −143 ppm in 1, 3, 6, 7, and 8. Compounds 3 and 4 each exhibit a single peak at chemical shift of 23.27 ppm (3) and 30.49 ppm (4) for dppf and PPh3 ligands in the 31P NMR spectrum. Though the chemical shift value of 3 is not in the range of those found for copper(I) dppf complexes, the value is C


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Inorganic Chemistry

Figure 1. (a) Molecular structure of the [Cu8(μ4-H){S2CNMeCH2Fc}6]+(1) (Fc = ferrocene). ORTEP of tetracapped tetrahedral core with an interstitial hydride [Cu8H] (30% thermal ellipsoid). Ranges of selected bond lengths [Å] and angles [deg]: Cuv···Cuv, 2.868(3)−3.06(4); Cuv··· Cucap, 2.601(2)−2.6309(19); Cuv−S, 2.3716(18)−2.4335(17); Cucap−S, 2.1987(17)−2.2608(11); S···S (bite), 3.067(2); Cu−S−Cu, 68.40(6)− 69.88(7); S−Cu−S, 104.71(7)−121.01(9). Symmetry code A: −x + y, −x, z; B: −y, x − y, z; C: −x, −y, −z; D: y, −x + y, −z + 1; E: x − y, x, −z + 1; F: −x, −y, −z + 1; G: −y + 1, x − y, z; H: −x + y + 1, −x + 1, z.

hold the bulky n-butyl substituents without any steric clashes and is quite stable under normal conditions. Further the robust nature of Cu28H15 (7) core is strongly suggested by ESI mass spectrometric analysis (Figure S12). Presumably the [Cu28(D)15(S2CNiPrCH2Fc)12](PF6) cluster formation takes place involving the enlargement of the original core of Cu7D (Cu7D → Cu8D → Cu28D15).24 Hence the present studies offer a facile approach for the synthesis of polyhydrido metal clusters anchored by multiferrocene assemblies. Although we successfully demonstrated the formation of [Cu 2 8 (D) 1 5 (S2CNiPrCH2Fc)12](PF6), due to its high instability, isolation and detailed characterizations are unsuccessful. Very interestingly our recent investigations have proved that under similar reaction conditions the use of dithiophosphates instead of dithiocarbamates results in distinctly different assemblies of [Cu20H11{S2P(OiPr)2}9]17 and [Cu32(H)20{S2P(OiPr)2}12].18 Obviously these diverse results are generated by the differences in ligands’ “bite distance”.25 Further these molecules are proven to be promising materials for hydrogen storage. The ESI mass spectrum for 1, 3, and 7 shows molecular ion peaks at m/z 2334.3, 2058.9, and 4246.2, respectively. An additional peak is shown at m/z 1166.7 in the ESI mass spectrum of 1; the possible assignment for this species is {Cu 3 (S 2 CNMeCH2Fc)3}+ [Figure S1a,b]. Similarly an additional peak at m/z 1616.1 shown in mass spectrum for 3 could arise from fragmentation of the parent ion; the possible assignment for this species is [Cu3(dppf)2(S2CNiPrCH2Fc)(S2)]+ [Figure S3a,b)]. The ESI mass spectrometry for 2 displays a single peak at m/z 2502.4 corresponding to an adduct ion [{Cu7(H)(S2CNiPrCH2Fc)6}(Cu)]+ instead of molecular ion peak. This is not surprising since an unstable neutral Cu7H cluster can be transformed into stable Cu8H by uptaking one Cu+ ion in the gas phase (Figure S2).15c Only fragment peaks were observed for 4.

contains a Cu8H core surrounded by six ferrocene dithiocarbamate ligands. Its charge neutrality is balanced by a PF6 anion. In fact the metallic core is disordered and can be understood as two cubes residing one inside the other.15a Since only four copper atoms in each cube are fully occupied, the disordered framework can be modeled as a tetracapped tetrahedral core. Whereas the tetrahedron (Cu2A, Cu2B, Cu2D, and Cu3 abbreviated as Cuv) comes from an inner cube, the four capping atoms (Cu1, Cu4A, Cu4B, and Cu4C abbreviated as Cucap) on four triangular faces of the tetrahedron are provided by the outer cube. A perspective view of molecule together with the atomic numbering scheme is illustrated in Figure 1. The Cuv··· Cuv edge distances of the tetrahedron and the Cuv···Cucap bond distances fall in the ranges of 2.868(3)−3.06(4) Å and 2.601(2)−2.6309(19) Å, respectively. These values are similar to those observed in [Cu8(H){Se2P(CH2CH2Ph)2}6]+ and [Cu8(H){Se2P(OiPr)2}6]+,15d,f but Cuv···Cuv distances are slightly shorter than those in [Cu8(H){S2CC(CN)2}6]+, 3.077(7)−3.287(12).15b Futher Cuv···Cucap distances in this cluster are shorter than the sum of the van der Waals radii for copper (2.80 Å). The average Cu−μ4-H distance, which hydride anion located at the center of the tetrahedron, is observed to be 1.81(6) Å, comparable with [Cu8(H){S2CNnPr2}6]+ (average (av) 1.80(12) Å).15c It is worthy to mention here that an interstitial hydride trapped in a Ln(III) tetrahedral cage26 has been reported. The hydride ion encapsulated in the Cu8 cage was resonated at 6.99 ppm in 1 H NMR spectrum, which is in good agreement with the previously reported value of 7.05 ppm for [Cu 8 (H){S2CNnPr)2}6]+. The surface of the Cu8H core was further surrounded by six ferrocene dithiocarbamates ligands on the periphery using tetrametallic tetraconnective (κ4: μ2-S; μ2-S) mode of bridging. The Cuv−S and Cucap−S bond distances fall in the range of 2.3716(18)−2.4336(18) Å and 2.1987(17)− 2.2608(11) Å. All the ferrocene units are directed away from the central core and are spatially well-separated from each other. The distances between adjacent iron centers are greater than 7 Å. The dihedral angle in the Cu4 butterflies are in the order of 155.8(6)° to 156.7(1)°, and the average intraligand S···

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X-RAY CRYSTALLOGRAPHY [Cu8(μ4-H){S2CNMeCH2Fc}6](PF6) (1). The structure was solved in trigonal P3̅ space group. The single-crystal X-ray analysis clearly demonstrates that 1, a cationic compound, D


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Inorganic Chemistry

Figure 2. (a) Molecular structure of the [Cu7(μ4-H){S2CN(iPr)CH2Fc}6] (2) (Fc = Ferrocene). (b) ORTEP of tricapped tetrahedral core with an interstitial hydride [Cu7H] (20% thermal ellipsoid). Ranges of selected bond lengths [Å] and angles [deg]: Cuv···Cuv 2.332(6)−2.552(5), Cuv··· Cucap 2.131(5)−2.790(5), Cuv−S 2.082(4)−2.860(5), Cucap−S 2.1191(14)−2.3742(15), S···S (bite) 3.022(3); Cu−S−Cu 52.93(11)−68.10(11), S−C−S 121.0(2)−121.3(2). Symmetry code A: −x, −y + 1, −z + 1.

Figure 3. (a) Molecular structure of the [Cu3{S2CN(Bz)(CH2Fc)}2(dppf)2]+ (3) (Fc = ferrocene). (b) ORTEP for core (3) (30% thermal ellipsoid). The phenyl rings and hydrogen atoms were omitted for clarity. Ranges of selected bond lengths [Å] and angles [deg]: Cu−P, 2.253(3)− 2.313(3); Cu−S, 2.242(3)−2.413(3); P−Cu−S, 94.87(9)−122.56(9); S−Cu−S, 109.99(9)−124.27(10); P4−Cu1−P3 (bite), 113.11(9).

Fourier maps, which encapsulated in the center of the tetrahedron to form a [Cu7(μ4-H)] core. A perspective view of molecule together with the atomic numbering scheme is illustrated in Figure 2. The central tetrahedron of Cu4H core approaches an elongated trigonal pyramid with a hydride atom encapsulated in its cavity, where the elongated edges are in a range of 3.203(9)−3.410(9) Å. The Cuv···Cuv and Cuv···Cucap distances are in the order of 2.332(6)−2.552(5) and 2.131(5)− 2.790(5) Å slightly shorter than the sum of the van der Waals radii for two copper atoms, 2.80 Å. The encapsulated hydride is appeared as a broad singlet at 7.4 ppm, which is closer to 6.9 ppm of 1 but significantly deviated from the corresponding 6.5 ppm for [Cu7(μ4-H){S2C(aza-15-crown-5)}6] reported previously.15c This could be due to the more asymmetrical orientation of tricapped tetrahderon geometry and different electromeric effects from ferrocene-substituted dithiocarbamate ligands. The average Cu−μ4-H distance is 1.85(12) Å larger than 1.67(9) Å of 1 and is comparable with [Cu7(μ4H){S2C(aza-15-crown-5)}6] (av 1.86(2) Å) affirmed by neutron diffraction. Peripheral ligations are provided by six

S bite distance is 3.067(2) Å, whose values are similar to those of [Cu8(H){S2CNnPr)2}6]+. [Cu7(μ4-H){S2CN(iPr)CH2Fc}6](2). The single-crystal X-ray diffraction studies reveal that the compound (2) is a neutral Cu7 cluster, which crystallizes in the triclinic, P1̅ space group. The cluster consists of a [Cu7(μ4-H)] core with tricapped tetrahedral geometry. The seven copper atoms are disordered to distribute over 16 positions of two concentric cubes; this arrangement is not uncommon in the [Cu7(μ4-H)] core, and some examples have been found for Cu with dithio/seleno carbamate ligands. 15c,e The disorder of copper atoms demonstrated complexity in the crystal, where their occupancy was refined with free variables initially. As a result, the sum of all disordered copper sites is seven. No counter-anions can be located in the Fourier maps, which excluded the possibility of [Cu8(μ4-H){S2CN(iPr)CH2Fc}6]PF6. Cu5, Cu6A, Cu7 and Cu8A (abbreviated as Cuv) as a tetrahedron with three copper atoms, Cu2, Cu3A, and Cu4A (abbreviated as Cucap), capped on three elongated triangular faces constitute a tricapped tetrahedron framework. A hydride atom was located in the E


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Inorganic Chemistry

Figure 4. (a) Molecular structure of the [Ag(PPh3){S2CNMe(CH2Fc)}]2 (4) (Fc = ferrocene). (b) ORTEP for core (4) (30% thermal ellipsoid). Ranges of selected bond lengths [Å] and angles [deg]: Ag−P, 2.4190(6); Ag−S, 2.5597(6)−2.7960(7); P−Ag−S, 113.06(12)−127.46(2); S−Ag−S, 67.416(19)−109.336(17); S−Ag−S (bite), 67.416(19). Symmetry code *: −x + 1, −y, −z + 1.

in the ranges of 2.253(3)−2.313(3) and 2.242(3)−2.413(3) Å, respectively. The bridging Cu2−P2 [2.270(3) Å] distances are shorter but presumably stronger than chelating Cu1−P3 [2.310(3) Å] bonds. The P4−Cu1−P3 bite angle is 113.11(9)°. The bond angles around the three coordinate copper atoms (Cu2 and Cu3) are in a range of 116.18(10)− 124.27(10)°, which is close to the ideal trigonal-planar coordination angles of 120°. The angles around the fourcoordinated copper (Cu1) are in a range of 94.86(9)− 122.56(9)°. For dppf, the torsion angle between the two planes formed by Fe−C−P is 45.58° and 80.33°. It seems that the molecular core is a sterically demanding system that forces the dppf ligand to adopt two different conformations. [Ag(PPh3){S2CNMe(CH2Fc)}]2 (4). The single-crystal X-ray diffraction studies reveal that the compound 4 is a dinuclear silver cluster, which crystallizes in the triclinic space group, P1̅. The structure is similar to the previously reported [Ag(L)PPh 3 ] 2 (L = N-benzyl-N-methylpyridyldtc, bis(Nmethylpyridyl)dtc, and [CuI(S2CNEt2)PR3]2 (R = OMe, Me, and Et)) clusters.30,31 The dinuclear cluster was stabilized by two ferrocene dithiocarbamate ligands and two triphenylphosphine ligands. The two dithiocarbamate ligands are connected to two silver atoms via dimetallic-triconnective chelating bridging mode (μ2, κ3-S1, S1*, S2), and the fourth coordination is satisfied by the triphenylphosphine ligand, resulting in distorted tetrahedral geometry around the silver atoms. The structure can be best visualized as a Ag2S4C2 core adopting a chair conformation. A perspective view of molecule together with the atomic numbering scheme is illustrated in Figure 4. The Ag···Ag distance in Ag2S4C2 core is 3.1312(4) Å, which is shorter than the sum of the van der Waals radii for silver (3.40 Å) and is consistent with the earlier reported values of 2.983(1) and 3.004(1) Å for [Ag(L)PPh3]2. Interestingly, in the recently reported [CuI(S2CNEt2)PR3]2 (R = OMe, Me, and Et) clusters it was shown that the Cu2S4C2 core ring geometries can be altered by varying electron-withdrawing or -donating substituents on triphenylphosphine ligands. The Ag−S and Ag−P distances are in the order of 2.5597(6)−2.7960(7) Å and 2.4190(6) Å, respectively. The S1*−Ag1−S2 bite angle is 67.416(19)°, and the P−Ag−S and S−Ag−S angles range from 113.06(12)−127.46(2)° to 67.416(19)−109.336(17)°, respectively. Interestingly the two triphenylphosphine ligands are in a trans orientation which could be due to the CH···CH (2.308 Å)

ferrocene dithiocarbamate ligands. The six ferrocene ligands enfolding the [Cu7(μ4-H)] core appears dangling, oriented away from the core, and spatially separated from each other. The distance between the neighboring iron atoms is greater than 7 Å. The ligands are coordinated to the copper atoms in a bidentate fashion, each behaving as a bridging ligand. The three Cu4 butterflies in the [Cu7(μ4-H)] core are tetrametallictetraconnective (κ4: μ2-S, μ2-S) by two ligands and trimetallictetraconnective (κ3: μ2-S, μ2-S) by one ligand. The rest of the ligands are connected to Cu3 traingles (△Cu3A-Cu6A-Cu8A, △Cu2−Cu7−Cu8A, △Cu4A-Cu6A-Cu7) via trimetallictetraconnective (κ3: μ2-S, μ2-S) and trimetallic-triconnective (κ3: μ2-S, μ-S) nature of bonding. The Cuv−S and Cucap−S bond lengths are in the ranges of 2.082(4)−2.860(5) Å and 2.1191(14)−2.3742(15) Å, respectively. The dihedral angle in the Cu4 butterflies ranges from 166.0 to 177.0°. The intraligand S···S bite distance in the dithiocarbamate ligand is 3.022(3) Å, which is in good agreement with [Cu7(μ4-H){S2C(aza-15crown-5)}6], 3.041(2) Å. [Cu3{S2CN(Bz) (CH2Fc)}2(dppf)2](PF6) (3). The singlecrystal X-ray diffraction studies reveal that the compound (3) is a cationic trimetallic cluster consisting of one tetrahedral copper and two trigonal planar copper centers, each being bridged by two dppf and two dithiocarbamate ligands. Whereas the two dithiocarbamate ligands are coordinated to three CuI atoms via a trimetallic-triconnective (κ3: μ2-S; μ-S) mode of binding, the dppf ligand serendipitously uses both bridging (μ, κ2-P1, P2-dppf) and chelating (P3, P4-dppf) modes for the construction of trimetallic CuI assembly. A perspective view of molecular cation together with the atomic numbering scheme is illustrated in Figure 3. It is worth mentioning that although the bridging and chelating coordination modes of dppf ligand are well-documented,27 only a few examples displayed in both chelating and bridging modes in the same compounds have been previously described. Notable examples are [M2(dppfP,P1)2(μ-dppf)]2+ (M = Cu, Ag, or Au) and [Pd3(η2dppf)(dppf)(μ3-S)2Cl2].28 It is expected that the tricoordinated copper atoms in the cluster are formed because of strong steric hindrance induced by the bulky phenyl stubstituents on the dppf and ferrocene dithiocarbamate ligands. There are instances in the literature where the introduction of bulky substituents on the dppf ligands leads to trigonal planar copper complexes.29 There are totally four ferrocene units enfolding the copper(I) framework. The Cu−P and Cu−S distances are F


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Inorganic Chemistry

Cu atoms of the rhombicuboctahedron square and two Cu atoms of the inner tetrahedron) and one is tetracoordinated (μ4-H, found in tetrahedral geometry at the cluster center), respectively. The line joining eight μ3-H and six μ-H (four μ5-H and two μ6-H) ions resembles a cube and an octahedron, respectively. The 1H NMR and 2H NMR studies (Figure S11) reveal that these two (four μ5-H and two μ6-H) sets of hydrides are chemically equivalent and cannot be distinguishable even at the low temperature, suggesting that all these hydrides along with the four copper atoms of inner tetrahedron involves in rapid fluxional process much faster than the time scale of an NMR experiment.16 Thus, each inner copper atom coordinates to three hydrides to satisfy the coordination sphere, and the distorted tetrahedral coordination geometry around the copper atom of the Cu24 core comes from S2H2 coordination. Finally the overall structure can be visualized concentrically as H(center)@Cu 4 (tetrahedron)@H 6 (octahedron)@Cu 24 (rhombicuboctahedron)@H8(cube)@S24(truncated octahedron).16

interactions between phenyl rings of PPh3 and ferrocene moiety of another cluster unit (Figure S16). [Cu28H15{S2CNnBu2}12](PF6) (7). The single-crystal X-ray diffraction studies reveal that the compound (6) is a cationic cluster crystallizes in the triclinic, P1̅ space group. The charge neutrality was balanced by a PF6 anion in the crystal lattice. The molecule resembles a truncated cubic cluster totally built of 28 copper atoms, 15 hydrides, and 12 dtc ligands. A perspective view of the molecule is shown in Figure 5a. The Cu28

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CYCLIC VOLTAMMETRY The cyclic voltammetric studies for 1, 2, and 4 were performed in oxygen-free dichloromethane at room temperature using tetraethylammonium perchlorate (TEAP) as the supporting electrolyte (vs Ag/Ag+) reference electrode, Pt wire as an auxiliary electrode, and glassy carbon as a working electrode. The voltammogram illustrates an irreversible redox peak (Figure 6). The E1/2 values for 1, 2, and 4 are 0.23, 0.17, and

Figure 5. (a) Molecular structure of [Cu28(H)15(S2CNnBu2)12]+ (7) (30% thermal ellipsoid). (b) Distorted rhombicuboctahedral core containing 24 Cu atoms. (c) Each of the 12 square faces of the Cu24 core is capped by a dtc ligand. (d) Rhombicuboctahedral core with 15 hydrides and a central Cu4 tetrahedron. Ranges of selected bond lengths [Å] and angles [deg]: Cu···Cu, 2.466(9)−3.041(2); Cu−S, 2.3503 (avg.); S···S (bite), 3.054 (av); Cu−S−Cu, 62.64(4)−73.18(4); S−Cu−S, 95.58(3)−107.92(4). Color code: cyan, CuRhom; blue, Cutet; yellow, S; violet, N; gray, C; red, H.

framework can be seen as a slightly distorted Cu 24 rhombicuboctahedron wherein 12 of 18 square faces on the rhombicuboctahedron are coordinated by dtc ligands (Figure 5b,c). The additional four copper atoms are disordered at 12 positions, which can be best described as a tetrahedral arrangement inside the Cu24 rhombicuboctahedron.16 The CuRhom−CuRhom distances are in the range of 2.4935(14)− 2.7682(6) Å, which are in well agreement with [Cu28(H)15(S 2 CN n Pr 2 ) 12 ]PF 6 [2.603(1)−2.824(1) Å], 16 [Cu 8 (H){S 2 CN n Pr 2 } 6 ] + [2.576(1)−2.989(2) Å], [Cu 20 H 11 {S 2 P(OiPr)2)9]17 [2.5284(9)−2.7542(7) Å], and [Cu14H12(phen)6(PPh3)4][Cl]2 (av 2.655 Å).32 There are 12 dtc ligands at the outer shell of the cluster core each bridging four metal centers in a (μ2, μ2) fashion. The 24 sulfur atoms above the rhombicuboctahedral core represent a truncated octahedral cage. The 12 dtc ligands provide a nonpolar cover over the cluster core, making the molecule highly soluble in a wide range of organic solvents. The average Cu−S bond length, S···S bite distance are 2.353 and 3.054 Å, respectively, which are comparable to [Cu28(H)15(S2CNnPr2)12]PF6 (2.354 and 3.059 Å). The Cu−S−Cu and S−Cu−S bond angles are in ranges of 62.64(4)−73.18(4) and 95.58(3)−107.92(4). Further the cluster core is stabilized by 15 hydride ions and an inner tetrahedron built by four copper atoms (Figure 5d). Of 15 hydride ions, eight are tricoordinated (μ3-H, capping the eight triangular faces of Cu24 rhombicuboctahedron), four are pentacoordinated (μ5-H, connect to four Cu atoms of the rhombicuboctahedron square and one Cu atom of inner tetrahedron), two are hexacoordinated (μ6-H, connect to four

Figure 6. Cyclic voltammogram of 1, 2 and 4 in dichloromethane (1 × 10−3 M TEAP) at 298 K with scan rate of 0.05 mV/s.

0.13 V, respectively, comparable with ferrocene 0.19 V. At higher scan rates peak broadening was observed indicating the irreversibility of the electron-transfer process (Figures S13− S15). The single oxidation peak of various ferrocene units at single unique potential value [0.398 V (1), 0.354 V (2), and 0.285 V (4)] indicates that six ferrocene moieties are oxidized in a single step and are electrochemically independent of one another. The observation of a single reduction peak [0.065 V (1), 0.024 V (2), and 0.026 V (4)] was the most intriguing aspect because they are much broader in length than the oxidation peaks. We expect the displayed single reduction peak may in fact correspond to reduction of all the six ferrocenium moieties. The broadening process of the reduction peaks may G


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Inorganic Chemistry

DPX300 FT-NMR spectrometer that operates at 300.13 MHz while recording 1H, 46.1 MHz for 2H, and 121.49 MHz for 31P. The 31P{1H} spectra were referenced externally against 85% H3PO4 (δ = 0 ppm). The chemical shift (δ) and coupling constant (J) are reported in parts per million and hertz. The NMR spectra were recorded at ambient temperature. ESI-mass spectra were recorded on a Fison Quattro BioQ (Fisons Instruments, VG Biotech, U.K). The cyclic voltammograms were recorded on a CH Instruments 611C electrochemical analyzer using a glassy carbon working electrode, Pt wire auxiliary electrode, Ag/AgNO3 reference electrode (0.33 V ± 10 mV vs standard calomel electrode), and standardized by the redox couple ferricinium/ ferrocene. Cyclic voltammetry studies for the compounds are performed in dichloromethane (1 × 10−3 M TEAP) at 298 K with scan rate of 0.05 mV/s. Electrochemical solutions were degassed with N2 and maintained under a positive pressure for the duration of the experiment. [Cu8(μ4-H){S2CNMeCH2Fc}6](PF6) (1). [Cu(CH3CN)4](PF6) (0.140 g, 0.388 mmol), K(S2CNMeCH2Fc) (0.100 g, 0.291 mmol), and (Bu4N) (BH4) (0.012 g, 0.048 mmol) in 30 mL of CH3CN were added to a Schlenk flask (100 mL) and were stirred at room temperature for 1 h under nitrogen atmosphere. The reaction mixture was evaporated to dryness under vacuum to obtain a yellow solid. The yellow solid was added to 30 mL of CH2Cl2 to form a yellow solution, and the solution was washed with deionized water (3 × 20 mL). The CH2Cl2 layer was separated and evaporated to dryness under vacuum to yield complex as a yellow powder. Yield: 0.10 g (78.1% based on Cu). mp 207.2 °C. Anal. calcd for C78H85Cu8F6Fe6N6PS12: C, 37.77; H, 3.46; N, 3.39%. Found: C, 38.14; H, 3.81; N, 3.17%. IR (υ cm−1, KBr pellet): 3443(m), 2924(m), 1626(w), 1492(s), 1430(m), 1388(m), 1257(m), 1218(m), 1180(m), 1105(m), 1073(m), 1000(m), 930(m), 840(s), 557(w), 481(w). 1H NMR (CDCl3, δ, ppm): 6.99 (bs,1H, μ4-H), 5.20 (12H, bs, −CH2Fc), 4.40 (12H bs, Cp), 4.19 (42H bs, Cp), 3.52 (18H, bs, CH3). 31P{1H} NMR (CDCl3, δ, ppm): −143.0 (septet, JPF = 706 Hz). ESI-MS (m/z) (Cal.): 2334.3 (2334.4) [Cu7(μ4-H){S2CN(iPr)CH2Fc}6] (2). [Cu(CH3CN)4](PF6) (0.110 g, 0.313 mmol), K(S2CN(iPr)CH2Fc) (0.100 g, 0.268 mmol), and (Bu4N) (BH4) (0.011 g, 0.044 mmol) in 30 mL of CH3CN were added to a Schlenk flask (100 mL) and were stirred at room temperature for 1 h under nitrogen atmosphere. The reaction mixture was evaporated to dryness under vacuum to obtain a yellow solid. The yellow solid was added to 30 mL of CH2Cl2 to form a yellow solution, and the solution was washed with deionized water (3 × 20 mL). The CH2Cl2 layer was separated and evaporated to dryness under vacuum to yield complex as a yellow powder. Yield: 0.08 g (78.4% based on Cu). mp 171.3 °C. Anal. Calcd for C90H109Cu7Fe6N6S12: C, 44.31.; H, 4.503; N, 3.44%. Found: C, 44.95; H, 4.96; N, 3.89%. IR (υ cm−1, KBr pellet): 3445(m), 3089(m), 2963(s), 2924(m), 1634(w), 1468(s), 1449(m), 1393(m), 1261(s), 1232(m), 1145(s), 1104 (m), 1026(m), 929(m), 841(s), 740(w), 618(m), 557(s), 481(m). 1H NMR (CDCl3, δ, ppm) 7.45 (bs,1H, μ4-H), 5.50−5.67 (6H, m, −CHMe2), 5.12 (12H, s, −CH2Fc), 4.45 (12H, bs, Cp), 4.19 (42H bs, Cp), 1.27 (36H, d, −CHMe2). ESI-MS (m/z) (Cal.): 2503.0 (2502.4). [Cu3{S2CN(Bz) (CH2Fc)}2(dppf)2](PF6) (3). [Cu(CH3CN)4](PF6) (0.088 g, 0.238 mmol), K(S2CN(Bz)CH2Fc) (0.100 g, 0.238 mmol), and dppf (0.130 g, 0.238 mmol) in 30 mL of THF were added to a Schlenk flask (100 mL) and were stirred at room temperature for 6 h under nitrogen atmosphere. The reaction mixture was evaporated to dryness under vacuum to obtain a yellow solid. The yellow solid was added to 30 mL of CH2Cl2 to form a yellow solution, and the solution was washed with deionized water (3 × 20 mL). The CH2Cl2 layer was separated and evaporated to dryness under vacuum to yield complex as a yellow powder. Yield: 0.15 g (74.6% based on Cu). mp 175.6 °C Anal. Calcd for C106H92Cu3F6Fe4N2P5S4: C, 57.77; H, 4.21; N, 1.27%. Found: C, 57.88; H, 4.31; N, 1.09%. IR (υ cm−1, KBr pellet): 3426(m), 3051(m), 2957(s), 2916(m), 1963(w), 1629(w), 1449(s), 1434(m), 1393(m), 1261(s), 1232(m), 1191(s), 1095(m), 1027(s), 923(m), 840(s), 744(w), 696(m), 633(w), 557(s), 488(m). 1H NMR (CDCl3, δ, ppm): 7.33−7.65 (34H, m, Ph), 5.30 (4H, s, −CH2Fc), 5.06 (4H, s, −CH2Ph), 3.86−4.43 (50H m, Cp). 31P{1H} NMR

not be due to electronic communication between various ferrocene units because all the ferrocene moieties located at the periphery of the cluster cores are oriented away from the central core and spatially well-separated by more than 7 Å from each other to behave independently, which was revealed from X-ray structural analysis and 1H NMR spectroscopy. The irreversible redox peaks were poorly defined, not well-resolved. The improvement in cyclic voltamogramms was not observed even after repeating the experiments with different electrodes and electrolytes. This kind of redox behavior is unknown in polyferrocenyl copper(I) complexes; however, examples of multiferrocenyl silver(I) chalcogenolate complexes [Ag7Br(dppe)3{SeCH2CH2O(O)CFc}6],10c [Ag36S9(SCH2CH2O{O}CFc)18(PPh3)3],4b and [Zn(tmeda){SCH2CH2O(O)CFc}2]10c have been reported recently, where the asymmetric behavior of the redox wave was attributed to some adsorption of the complex onto the electrode surface subsequent to oxidation of the iron center. In fact some dendrimers and metal nanoparticles (bearing terminal ferrrocenyl groups) adsorption to the electrode is readily observed by drastic differences in the shapes and sizes of the waves.4b So in the present case it is anticipated that due to similar adsorption phenomenon, the complexes are exhibiting cathodic wave higher and sharper than the forward wave. Recently [(FcSn)4E6] (Fc = ferrocenyl, E = S, Se) complexes displaying similar wave shape in cyclic voltammetry due to interaction of the Sn/E skeleton with the electrodes is also reported.10k In our recent report the cyclic voltammetry studies for (Cu8HL6)+ or (Cu7HL6) cluster cores display an irreversible wave indicating the formation of CuII species.15c Interestingly from the present study it can be understood that the oxidation of CuI to CuII is suppressed because of the presence of dominant redox-active ferrocenyl moieties on the cluster surface.19a The cyclic voltammograms for 3 were difficult to reproduce, so its electrochemistry was not studied; further, the compound also leads to electrode fouling.10d There are no additional peaks observed at more positive potential values for the oxidation of phosphorus atoms of the phosphine ligands in 4.

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CONCLUSION We have demonstrated the hydride ion mediated facile selfassembly of Cu8(μ4-H), Cu7(μ4-H), and Cu28H15 cores supported by multiferrocene assemblies. Core functionalization with redox-active ferrocenes at the periphery of the clusters has been achieved, and hence we have successfully anchored new functionality onto the hydrido copper(I) cores. The metal hydride clusters with maximum number of hydrides, anchoring maximum number of ferrocene units can have very interesting properties. The ongoing research is currently focused on this direction. Further we have also successfully synthesized and structurally characterized metal clusters supported by mixedligand systems incorporating four and two ferrocene units.

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EXPERIMENTAL SECTION

General Procedures. All chemicals were purchased from commercial sources and used as received. Solvents were purified following standard protocols. All reactions were performed under N2 atmosphere by using standard Schlenk techniques. The preparation of [Cu(CH3CN)4](PF6),33 K(S2CNRCH2FC) (R = Me, iPr, Ph), and the K(S2CNnBu2) ligands have been reported previously.19,34 Melting points were measured by using a Fargo MP-2D melting point apparatus. The elemental analyses were done using a PerkinElmer 2400 CHN analyzer. NMR spectra were recorded on Bruker Advance H


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Inorganic Chemistry

X-ray Crystallography. Crystals were mounted on glass fibers with epoxy resin, and all geometric and intensity data were collected on a Bruker APEXII CCD diffractometer using graphite monochromated Mo Kα radiation (λ = 0.710 73 Å). Data reduction was performed with SAINT-Plus software.35 An empirical absorption correction was applied using the SADABS program.36 Structures were solved by direct methods and refined by full-matrix least-squares on F2 using the SHELXL-2014/7 software package,37 incorporated in SHELXTL/PC version 6.14.38 The data collections for crystals of 1, 2, 3, 4, and 7 were performed at 150(2), 296(2), 296(2), 296(2), and 150(2) K, respectively. All Cu atoms in 1 are disordered over two positions with 50% occupancy. The copper atoms in 2 are disordered at 16 positions, and the sum of their site occupancy is seven. The four central copper atoms in 7 are disordered over 12 positions, constituting a cuboctahedral arrangement. The structures (1−4 and 7) reported herein have been deposited at the Cambridge Crystallographic Data Center, CCDC Nos. 1447513−1447517.

(CDCl3, δ, ppm): 23.27 (s), −143.0 (septet, JPF = 706 Hz). ESI-MS (m/z) (Cal.): 2059.0 (2058.9). [Ag(PPh3){S2CNMe(CH2Fc)}]2 (4). [Ag(CH3CN)4](PF6) (0.120 g, 0.291 mmol), Na(S2CN(Me)CH2Fc) (0.100 g, 0.291 mmol), and PPh3 (0.076 g, 0.291 mmol) in 30 mL of THF were added to a Schlenk flask (100 mL) and were stirred at room temperature for 6 h under nitrogen atmosphere. The reaction mixture was evaporated to dryness under vacuum to obtain a yellow solid. The yellow solid was added to 30 mL of CH2Cl2 to form a yellow solution, and the solution was washed with deionized water (3 × 20 mL). The CH2Cl2 layer was separated and evaporated to dryness under vacuum to yield complex as a pale yellow powder. Yield: 0.09 g (46.3% based on Ag). mp 130.3 °C. Anal. Calcd for C62H58Ag2Fe2N2P2S4: C, 55.21; H, 4.33; N, 2.08%. Found: C, 55.87; H, 4.52; N, 2.06%. IR (υ cm−1, KBr pellet): 3434(m), 3052(m), 2927(s), 1963(w), 1891(w), 1630(w), 1480(s), 1435(m), 1385(m), 1256(s), 1221(m), 1179(s), 1094(m), 1074(s), 998(w), 958(m), 935(m), 840(s), 744(w), 694(s), 633(w), 557(s), 504(m). 1H NMR (CDCl3, δ, ppm): 7.32−7.82 (30H, m, Ph), 5.11 (4H, S−CH2Fc) 4.43 (4H, bs, Cp) 4.16 (14H, bs, Cp), 3.28 (6H, S). 31 1 P{ H} NMR (CDCl3, δ, ppm): 30.49 (s). [Cu28D15{S2CNiPrCH2Fc}12](PF6) (6). [Cu(CH3CN)4](PF6) (0.190 g, 0.517 mmol), K(S2CN(iPr)CH2FC) (0.100 g, 0.269 mmol), and NaBD4 (0.033 g, 0.770 mmol) in 30 mL of THF were added to a Schlenk flask (100 mL) and were stirred at room temperature for 1 h under nitrogen atmosphere. The reaction mixture was evaporated to dryness under vacuum to obtain a red solid. The red solid was added to 30 mL of CH2Cl2 to form a red solution, and the solution was washed with deionized water (3 × 20 mL). The CH2Cl2 layer was separated and evaporated to dryness under vacuum to yield complex as a red powder. The compound is washed with MeOH and acetone to obtain fine orange powder. Yield: ∼0.04 g (36.6% based on Cu). IR (υ cm−1, KBr pellet): 3445(m), 2961(s), 2345(w), 1664(m), 1508(w), 1459(m), 1437(s), 1410(s), 1388(m), 1365(w), 1341(w), 1319(m), 1260(s), 1230(m), 1209(m), 1150(s), 1104(m), 1051(w), 1025(w), 932(m), 888(m), 860(m), 804(s), 704(w), 661(w), 620(s), 601(w), 576(w), 482(s). mp 221.3 °C (dec). 2H NMR (CH2Cl2, δ, ppm): −0.47 (8D), 1.74 (1D), 4.53 (6D). 31P{1H} NMR (CDCl3, δ, ppm): −143.0 (septet, JPF = 721 Hz) [Cu28H15{S2CNnBu2}12](PF6) (7). It was prepared in the similar fashion to 6. The stoichiometry of the reagents are [Cu(CH3CN)4](PF6) (0.200 g, 0.54 mmol), K(S2CNnBu2) (0.065g, 0.27 mmol), and LiBH4·THF (0.4 mL, 0.80 mmol). Yield: 0.048 g (57.0% based on Cu). mp 136 °C (dec). Anal. Calcd for C108H231Cu28F6N12PS24: C, 29.54; H, 5.30; N, 3.83%. IR (υ cm−1, KBr pellet): 3435(m), 2958(s), 2933(m), 2870(m), 1629(m), 1487(s), 1466(m), 1418(s), 1386(m), 1367(m), 1353(s), 1338(m), 1301(w), 1284(w), 1242(s), 1170(m), 1188(m), 1147(s), 1084(s), 1017(m), 964(m), 934(m), 914(m), 874(m), 841(s), 806(m), 628(w), 592(m), 557(m), 468(w). Found: C, 29.32; H, 5.40; N, 4.15%. 1H NMR (CDCl3, δ, ppm): −0.83 (bs, 8H, μ3-H), 0.89−0.95 (t, 72H, −CH3), 1.29−1.40 (m, 48H + 1 μ4-H, −CH2−CH2−), 1.56−1.84 (m, 48H, -CH2−CH2−), 3.94−4.00 (t, 48H, N−CH2−), 4.14 (bs, 6H, μ5,μ6-H). 31P{1H} NMR (CDCl3, δ, ppm): −143.0 (septet, JPF = 713 Hz). ESI-MS (m/z) (Cal.): 4246.2 (4246.92). [Cu28D15{S2CNnBu2}12](PF6) (8). Compound 8 was prepared in the similar fashion to 7 by replacing LiBH4·THF with NaBD4 (0.033 g, 0.80 mmol) Yield: 0.043 g (51.0% based on Cu). mp 135.6 °C (dec). Anal. Calcd for C108H216D15Cu28F6N12PS24: C, 30.44; H, 5.82; N, 3.94%. Found: C, 31.01; H, 6.03; N, 4.15%. IR (υ cm−1, KBr pellet): 3446(m), 2959(s), 2935(m), 2871(m), 2343(w), 1634(m), 1490(s), 1466(m), 1419(s), 1386(m), 1366(m), 1353(s), 1338(m), 1302(w), 1284(w), 1244(s), 1170(m), 1188(m), 1148(s), 1085(s), 1023(m), 964(m), 934(m), 914(m), 871(m), 840(s), 807(m), 628(w), 704(w), 628(w), 590(m), 557(m), 462(w). 1H NMR (300 MHz, CDCl3, δ, ppm): 0.92 (t, 72H, −CH3), 1.35 (m, 48H, −CH2−CH2−), 1.79 (m, 48H, −CH2−CH2−), 3.97 (t, 48H, N−CH2−). 2H NMR (CH2Cl2, δ, ppm): −0.73 (bs, 8D), 1.31(bs, 1D), 4.29 (bs, 6D). 31P{1H} NMR (CDCl3, δ, ppm): −143.0 (septet, JPF = 721 Hz). ESI-MS (m/z) (Cal.): 4258.3 (4262.01).

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.6b00201. ESI mass spectrum for 1, 2, 3, 6, and 7; 31P NMR spectrum for 3 and 4; 2H NMR spectrum for 6 and 8; cyclic voltammogram at various scan rates for 1, 2, and 4. (PDF) X-ray crystallographic information. (CIF)

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS Financial support from the Ministry of Science and Technology in Taiwan (MOST 103-2113-M-259-003) is greatly acknowledged.

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REFERENCES

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Ag(I) Dithiocarbamate Clusters

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