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Synthesis and Optical Properties of [Cu6E6(SnPh)2(PPh2Et)6] (E = S, Se, Te) Cluster Molecules Andreas Eichhöfer,*,†,‡,§ Michael Kühn,∥,⊥ Sergei Lebedkin,† Max Kehry,∥ Manfred. M. Kappes,†,∥ and Florian Weigend†,∥ †

Institut für Nanotechnologie, Karlsruher Institut für Technologie (KIT), Campus Nord, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany ‡ Lehn Institute of Functional Materials, Sun Yat-Sen University, Guangzhou 510275, People’s Republic of China § Karlsruhe Nano Micro Facility (KNMF), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany ∥ Institut für Physikalische Chemie, Karlsruher Institut für Technologie (KIT), Campus Süd, Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany S Supporting Information *

ABSTRACT: A homologous series of three copper−tin−chalcogenide cluster molecules [Cu6E6(SnPh)2(PPh2Et)6] (E = S, Se, Te) was synthesized by reactions of CuO(O)CCH3 and PhSnCl3 with E(SiMe3)2 in the presence of PPh2Et. The cluster cage structures are similar, with slight differences in the bridging modes of the respective chalcogenide ligands E. The onset of the optical absorption displays a significant decrease of ca. 1.1 eV on going from sulfur to tellurium. The differences in bonding and electronic excitations can be rationalized by DFT and TDDFT calculations. All complexes display near-infrared phosphorescence at cryogenic temperatures. In parallel with the absorption, the emission maximum shifts to lower energies in a series of sulfur, selenium, and tellurium compounds. In particular, the copper−tin−tellurium complex emits at an energy as low as ca. 0.97 eV (1280 nm).

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INTRODUCTION The synthesis of ternary cluster molecules has attracted some interest in the last few years.1 In general, ternary compounds may offer a greater compositional and structural diversity in comparison to the binary compounds and, correspondingly, a broader spectrum of tunable properties. Furthermore, some of the copper-based ternary compounds are viable candidates for a number of technical applications. One of the most prominent examples, CuInSe2 and its derivatives, has been investigated for thin film solar cell technology.2,3 Consequently, discrete cluster molecules of this latter type of compound were synthesized in order to study and model the growth and related property changes of the bulk material4−9 and to utilize them as singlesource precursors in the thermolytic generation of the respective chalcopyrite type ternary semiconductors.10−12 Recent investigations on related copper−tin−sulfur ternary systems have demonstrated interesting photoconductive properties of the extended cluster network compound (dienH2)Cu2Sn2S6.13 Similar materials synthesized by solvothermal reactions also include (DBUH)CuSnS3, (1,4-dabH2)Cu2SnS4,14 (enH)3Cu7Sn4S12, (trenH)Cu7Sn4S12, (enH)6+nCu40Sn15S60,15 and (enH2)2Cu8Sn3S12.16 However, only a limited number of the related molecular cluster compounds has been reported so far: for instance, [(Ph3PCu)6{(CH2)4SnS2}6Cu4Sn],17 [(RSnS3)2(CuPR3)6] (R = organic group),18−20 and [Cu4Sn2S12(MoO)2](NEt4)4.21 © 2017 American Chemical Society

Recently, we have reported on the optical properties of the polynuclear cluster (NBu4)[Cu19S28(SnPh)12(PEt2Ph)3] and the two trinuclear metal complexes [Cu2Sn(EPh)6(PPh3)2] (E = S, Se).22,23 These cluster compounds demonstrate a bright near-infrared (NIR) photoluminescence in the solid state at low temperatures. In particular, the trinuclear Cu2Sn chalcogenide compounds efficiently luminesce at long wavelengths of about 1020 and 1100 nm, respectively, and thus represent rare examples of NIR-emitting metal complexes. In this work, the three homologous copper−tin−chalcogenide clusters [Cu6E6(SnPh)2(PPh2Et)6] (E = S, Se, Te) were synthesized. Their optical properties were investigated by absorption and photoluminescence spectroscopy as well as by TDDFT calculations and were found to be significantly affected by variation of the chalcogen atom.

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RESULTS AND DISCUSSION Syntheses and Structures. From reaction solutions of CuOC(O)CH3 and PhSnCl3 with E(SiMe3) (E = S, Se, Te) in the presence of an excess of PPh2Et in organic solvents, [Cu6E6(SnPh)2(PPh2Et)6] (E = S (1), Se (2), Te (3)) can be obtained in the form of yellow, orange, and lilac crystals, respectively (Scheme 1). Received: June 13, 2017 Published: July 21, 2017 9330

DOI: 10.1021/acs.inorgchem.7b01495 Inorg. Chem. 2017, 56, 9330−9336

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Inorganic Chemistry

the increasing detection angle arise from the temperature difference between the data collections (single-crystal XRD at 180 K vs powder XRD at room temperature). Optical Properties. The formal exchange of the chalcogen atom from sulfur to selenium and tellurium in 1−3 has a distinct effect on the optical properties, as can be already concluded from the change of the visible colors from yellow in 1 to orange in 2 and dark lilac in 3 (Figure S7 in the Supporting Information). Absorption spectra of 1−3 have been measured for powdered crystals in a thin mineral oil layer between two quartz plates (Figures 2−4). In solution the clusters either are

Scheme 1. Synthesis of Compounds 1−3

Although the structural motifs of the cluster molecules in 1− 3 are similar, the compounds crystallize with different crystal structures in different space groups (Table S1 in the Supporting Information). However, all molecules show inversion symmetry (Figure 1 and Figures S1−S3 in the Supporting Information)

Figure 1. Molecular structures of 1−3 (C and H atoms omitted for clarity, ellipsoids drawn at the 50% probability level). For interatomic distances and bond angles see Table 1.

and are structurally related to [(PhSn)2(CuPMe2Ph)6S6], [(RSnS3)2(CuPPh3)6] (R = C(CH3)2CH2COCH3), and [(CuPPh3)6(S/Se)6(SnFc)2] (Fc = ferrocenyl),16−18 reported earlier. The polynuclear inorganic Cu/Sn/E core can be viewed to be formally composed of an almost regular E6 octahedron (no direct bonds between the chalcogen atoms) with two opposite trigonal faces symmetrically capped by PhSn units (for atomic distances and angles see Table 1). In 1, the six R3PCu Figure 2. Comparison of measured electronic spectra (powdered crystals in mineral oil) of 1 with calculated singlet excitation energies and oscillator strengths plotted as vertical lines (green) as well as with superimposed Gaussians of fwhm = 0.3 eV (black curve) to simulate the spectrum (see also Table 2 and Table S2 in the Supporting Information). The character of the peaks (up to 3.8 eV) was visualized using the nonrelaxed difference densities (see the Experimental Section). The contributions of occupied orbitals are plotted in red and those of the unoccupied orbitals in blue.

Table 1. Interatomic Distances (pm) and Bond Angles (deg) for 1−3a 1 (E = S)

2 (E = Se)

3 (E = Te)

Sn−E Cu−E Cu−P Cu····Cu E····E Sn····Sn

238.3−239.0 224.5−229.5 223.7−224.2 270.7−326.7 397.3−412.5 460.4

250.7−254.5 238.4−249.6 223.5−224.9 264.6−328.6 405.1−428.2 491.8

272.8−273.4 258.6−283.6 227.1−228.8 293.3−303.5 441.0−456.0 535.0

Cu−E−Sn Cu−E−Cu

96.02−113.3 73.2−92.2

73.6−111.1 66.53−125.8

66.7−108.2 64.95−108.1

partially insoluble or visibly decompose (see Figure S8). The absorption onsets of the solid-state spectra were evaluated by a linear interpolation of the rise of the first absorption features to its intercept with the x axis (Figures 2−4). The absorption onsets were found at 2.83, 2.32, and 1.71 eV for 1−3, respectively. Accordingly, the onset shifts to lower energy by approximately 0.5 eV from 1 to 2 and by as much as 1.1 eV from 1 to 3. In order to rationalize this behavior, singlet excitation energies were calculated by using the experimental structure parameters within time-dependent density functional theory (TDDFT) (Tables S2−S4 in the Supporting Information; for details see the Experimental Section). In Table 2, the calculated energies for excitations with significant oscillator strengths (>5 × 10−3) are given together with the respective molecular orbitals involved. From these transitions the spectra were simulated by superimposing Gaussians with a full width at halfmaximum of 0.3 eV. Figures 2−4 demonstrate a good agreement between the calculated singlet excitations and measured solid-state spectra of 1−3. The remarkable red shift

a

Values are rounded to one digit after the comma. Maximum esds for this digit are 1 for the atom distances and 2 for the bond angles.

units bridge the free edges in a μ2 fashion. In 2 and 3, they increasingly act as μ3 bridges over the triangular faces, being, however, unsymmetrical with one Cu−E bond always being longer than the other two. Differences in the geometrical parameters of 1−3 are related to the increasing ionic radii from S2− to Se2− and Te2− (170, 184, 207 pm).24 We note that molecular compounds which include Cu−Te−Sn entities have so far not been reported in the CCDC Database. A comparison of the measured and calculated X-ray powder diffraction patterns for 1−3 confirms their crystalline purity with respect to the formation of other crystalline phases/ compounds (Figures S4−S6 in the Supporting Information). Slightly increasing differences in the position of the peaks with 9331


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Inorganic Chemistry Table 2. Calculated (TDDFT) Electronic Excitation Energies in 1−3a ΔE

f

character

1

2.92 3.05 3.14 3.19 3.23

0.0051 0.0104 0.0066 0.0143 0.0091

2

2.78 2.90 2.96

0.0167 0.0378 0.0083

2.99 3.01 2.12 2.23 2.29 2.45 2.86

0.0079 0.0027 0.0056 0.0109 0.0121 0.0010 0.0004

au (HOMO) → ag (LUMO+1) au (HOMO) → ag (LUMO+2) au (HOMO−1) → ag (LUMO+1) au (HOMO) → ag (LUMO+4) 1/2 au (HOMO) → ag (LUMO+6) 1/2 au (HOMO) → ag (LUMO+6) au (HOMO) → ag (LUMO) au (HOMO−2) → ag (LUMO) 1/3 au (HOMO) → ag (LUMO+4) 1/3 ag (HOMO−1) → au (LUMO+3) 1/3 au (HOMO) → ag (LUMO) ag (HOMO−1) → au (LUMO+1) au (HOMO) → ag (LUMO+2) au (HOMO) → ag (LUMO) au (HOMO−1) → ag (LUMO) au (HOMO−3) → ag (LUMO) ag (HOMO−2) → au (LUMO+1) ag (HOMO−4) → au (LUMO+1)

3

Figure 3. Comparison of measured electronic spectra (powdered crystals in mineral oil) of 2 with calculated singlet excitation energies and oscillator strengths plotted as vertical lines (green) as well as with superimposed Gaussians of fwhm = 0.3 eV (black curve) to simulate the spectrum (see also Table 2 and Table S3 in the Supporting Information). The character of the peaks (up to 3.1 eV) was visualized using the nonrelaxed difference densities (see the Experimental Section). The contributions of occupied orbitals are plotted in red and those of the unoccupied orbitals in blue.

Parameters: transition energy ΔE (eV), corresponding oscillator strength f. For the spectra, see Figures 2−4.

a

maximum in 3, is also well reproduced by our TDDFT calculations. We further investigated the characters of the lowest energy transitions. In view of the formal distribution of charges in 1−3 (Cu+, E2−, PhSn3+) and according to recent investigations on related trinuclear copper complexes [Cu2(EPh)6Sn(PPh3)2] (E = S, Se)21 one might qualitatively expect the lowest energy transitions to be of Cu/E to Sn or Sn/E charge transfer type. Correspondingly, the shift in the absorption onset might then be rationalized in terms of optical electronegativity,25 meaning that it should be more difficult to remove electrons from sulfur (electronegativity χAR = 2.44)26 than from tellurium (χAR = 2.01). Consequently, the energy of the HOMO should be lower (higher negative energy) in 1 than in 3, whereas the energetic sequence of the LUMOs on going from 1 to 3 should be inverse, if chalcogen atoms are involved. These considerations would then qualitatively rationalize the observed increase in the HOMO−LUMO gap. However, the calculations revealed that this is only partially the case for 1−3. According to a Mulliken population analysis (Table S6 in the Supporting Information) of the molecular orbitals of 1−3, the six HOMOs in each compound are dominantly located at the copper and chalcogen atoms. This rationalizes the expected and observed increase in HOMO energies from 1 to 3 (Figure 5). In contrast, such a trend is not observed for the LUMOs. Mulliken population analysis of the six energetically lowest LUMOs reveals that in the case of 3 tin orbitals contribute to a significant extent to LUMO and LUMO+1, whereas in 2 a tin contribution is restricted to the LUMO and is much smaller. In 1 these unoccupied orbitals are almost exclusively localized at the phenyl rings of the phosphine ligands. As examples, molecular frontier orbitals involved in the relevant (lowest energy) electronic transitions of 1−3 are shown in Figures S9− S11 in the Supporting Information. The difference in the character of the LUMOs has a direct effect on the character of the electronic excitations. Green lines in Figures 2−4 correspond to electronic transitions with contributions of transitions to energetically low lying LUMOs

Figure 4. Comparison of measured electronic spectra (powdered crystals in mineral oil) of 3 with calculated singlet excitation energies and oscillator strengths plotted as vertical lines (green) as well as with superimposed Gaussians of fwhm = 0.3 eV (black curve) to simulate the spectrum (see also Table 2 and Table S4 in the Supporting Information). The character of the peaks (up to 2.6 eV) was visualized using the nonrelaxed difference densities (see the Experimental Section). The contributions of occupied orbitals are plotted in red and those of the unoccupied orbitals in blue.

of the absorption onset in the experimental spectra from 1 to 3 (ca. 1.1 eV) is mirrored by an analogous shift in the simulated spectra (ca. 1.1 eV). In addition, the shape of the absorption spectra, in particular the energetically lowest absorption 9332


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Inorganic Chemistry

Figure 5. Calculated molecular orbital diagrams of 1−3. The dashed line separates occupied orbitals from the unoccupied orbitals.

with tin character: i.e., the LUMO in the case of 2 and the LUMO and LUMO+1 in the case of 3 (Tables S5 and S6 in the Supporting Information). In 3 these transitions mostly form the isolated lowest energy band, whereas they are shifted to higher energies and overlapped by transitions to the phenyl ligands in the case of 2. Accordingly, the visualization of the nonrelaxed difference densities (see the Experimental Section) for selected regions of the spectra of 1−3 reveals the following picture (Figures 2−4 and Figures S12−S14 in the Supporting Information). For all compounds, transitions involve occupied orbitals located dominantly at the copper and the chalcogen atoms but differ in the (unoccupied) target orbitals. In 3, a significant amount of electron density is transferred to orbitals with distinct tin and tellurium character for the energy region between 1.8 and 2.6 eV. These lowest excitations are energetically well separated from the higher excitations, in both the measured and the calculated spectrum. In 2, significant transfer of electron density to tin-dominated orbitals occurs at higher energies, 2.8−3.1 eV. However, at these energies a large percentage of electron density is also transferred to the phenyl rings of the PPh2Et ligands. This means that the two different types of excitations (transfer to tin-dominated orbitals or to ligand orbitals) are not energetically separated here. In 1, the transfer to the phenyl rings of the PPh2Et ligands is the dominant process over the whole investigated energy range of the spectrum. Compounds 1−3 represent a further (rare) group of metal complexes which demonstrate near-infrared photoluminescence (NIR PL). Figure 6 combines PL excitation (PLE) and emission spectra of these complexes measured as crystalline powders at various temperatures down to 16 K. In parallel to the red shift of the absorption (mirrored in the PLE spectra), the emission maxima are positioned at about 800, 920, and 1280 nm (1.55, 1.35, and 0.97 eV) for 1−3, respectively. Complex 3 displays again the largest red shift relative to 1. The PL intensity of 1−3 is rather weak, particularly in the case of 3, and is readily detectable only at temperatures below ∼150 K. On the other hand, to our knowledge, such a low-energy PL as emitted by 3 has not yet been reported for copper complexes. In fact, in order to record its emission spectrum tailing up to ∼1700 nm, we applied a FTIR-PL technique which allows for the extended spectral range and higher sensitivity (see the Experimental Section). We attribute the emission of 1−3 to phosphorescence. Its relatively weak intensity and short lifetime (on the time scale of a few microseconds for 1 and 2 and submicroseconds for 3 at T = 16 K; see Figure S16 in the Supporting Information) are explained by the efficient

Figure 6. Photoluminescence excitation (PLE) and emission (PL) spectra of 1−3 (powdered crystals in oil) measured at low temperatures down to 16 K. Emission and excitation wavelengths were 800, 900, and 1500 nm and 400, 480, and 600 nm for 1−3, respectively. Complex 3 was measured by using a FTIR-PL technique providing for the extended NIR emission range and higher sensitivity (see the Experimental Section).

nonradiative relaxation. Interestingly, in contrast to the counterpart absorption spectra, the PLE spectra of 1−3 are more structured (probably partially due to cryogenic temperatures) and show distinctly reduced intensities for excitations above ∼3.5 eV (cf. Figures 2−4 and 6). This suggests the presence of additional efficient nonradiative relaxation channels for the higher energy excited states in 1−3. Finally, we note that the large Stokes shifts in the absorption/PLE and emission spectra (Figures 2−4 and 6) indicate significant structural relaxation upon intersystem conversion in 1−3.

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CONCLUSION We have described the synthesis of three homologous mixedmetal ternary cluster molecules [Cu6E6(SnPh)2(PPh2Et)6] (E = S, Se, Te) and the comparative investigation of their optical properties by absorption and luminescence spectroscopy and TDDFT calculations. The latter describes well the absorption spectra and reveals singlet excitations of different characters depending on the energy and the kind of chalcogen atom, with particularly pronounced effects for E = Te versus E = S, Se. We note here that a simple qualitative interpretation based on basic chemical assumptions or on analogy with other copper-based clusters would lead to an oversimplified picture and wrong conclusions regarding the character of excitations. Complementary to our recent findings for [Cu12E6(PR3)8] cluster molecules27 compounds 1 and 2 also demonstrate low-lying π* orbitals of phenyl ligands, which are partially still strongly involved in the lowest energy transitions. This suggests a possibility of significant variation of the optical properties of these clusters (and perhaps an increase in NIR PL intensity) via variation of the corresponding ligands. In particular, a cluster core “localization” of the lowest energy transitions might be achieved by the use of alkyl groups bound to the phosphorus and tin atoms. Compounds 1−3 demonstrate NIR phosphorescence of a weak to moderate intensity at cryogenic temperatures. Especially exciting is the observation of an 9333


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Inorganic Chemistry

On the basis of a crystal description numerical absorption corrections were applied for 1−3.31 The structures were solved with the direct methods program SHELXS of the SHELXTL PC suite of programs32 and were refined with the use of the full-matrix leastsquares program SHELXL. Molecular diagrams were prepared using Diamond.33 All Cu, P, S, Se, Sn, Te, and C atoms were refined in 1−3 with anisotropic displacement parameters, while H atoms were computed and refined, using a riding model, with an isotropic temperature factor equal to 1.2 times the equivalent temperature factor of the atom to which they are linked. In 2 two phenyl rings of the phosphine ligands are disordered and C atoms were refined isotropically with a split model of site disorder. Disordered toluene solvent molecules were identified within 3. CCDC 1537209 (1), 1537210 (2), and 1537211 (3) contain supplementary crystallographic data for this paper. X-ray powder diffraction patterns (XRD) for 1−3 were measured on a STOE STADI P diffractometer (Cu Kα1 radiation, germanium monochromator, Debye−Scherrer geometry, Mythen 1K detector) in sealed glass capillaries. Theoretical powder diffraction patterns were calculated on the basis of the atom coordinates obtained from single-crystal X-ray analysis by using the program package STOE WinXPOW.34 Physical Measurements. C, H, and S elemental analyses were performed on an Elementar Vario Micro cube instrument. Solid-state absorption spectra were measured in transmission mode on a PerkinElmer Lambda 900 spectrophotometer for samples which were prepared as micron-sized crystalline powders dispersed in a mineral oil layer between two quartz plates. These were placed in front of a Labsphere integrating sphere. Photoluminescence (PL) measurements were performed with the same sample preparations as for absorption measurements. PL measurements of 1 and 2 were recorded on a Horiba JobinYvon Fluorolog-3 spectrometer equipped with a Hamamatsu R5509 visibleNIR photomultiplier (∼300−1400 nm). Emission decay traces were recorded by connecting the photomultiplier to an oscilloscope (with a 500 or 50 Ω load) and using a N2 laser for pulsed excitation at 337 nm (∼2 ns, ∼5 μJ per pulse). The weak emission of 3 centered at ∼1280 nm and tailing up to ∼1700 nm was measured by using a FTIR-PL setup based on a FTIR spectrometer (Bruker IFS66) equipped with a high-sensitivity liquid-nitrogen-cooled germanium detector (∼900− 1700 nm). A scheme of the FTIR-PL setup is shown in Figure S9 in the Supporting Information. In fact, it is similar to that described previously for the NIR PL analysis of single-walled carbon nanotubes in aqueous or organic solvent dispersions.35 The photoexcitation unit of the Fluorolog spectrometer consisting of a 450 W xenon lamp and a PC-controlled monochromator was also applied in the second setup. In both experiments, the samples were fixed on a cold finger of an optical closed-cycle cryostat (Leybold) and could be cooled down to 16 K. A trolley-mounted cryostat holder also provided for positional and rotational adjustments of the cryostat. The latter could thus be readily moved between different apparatus. All emission spectra were corrected by using a standard lamp (L.O.T. Oriel) for the wavelengthdependent response of the corresponding spectrometer and detector (in relative photon flux units). Quantum Chemical Treatments. Calculations were done with TURBOMOLE36,37 employing Becke’s three-parameter hybrid functional with Lee−Yang−Parr correlation (B3LYP)38,39 and polarized double-ζ valence basis sets def2-SV(P)40 throughout. The electronic spectrum and the (nonrelaxed) difference densities for a group of transitions forming a peak were visualized at essentially no extra computational effort using the Python script PANAMA (peak analyzing machine).41 The contributions of occupied orbitals are plotted in red and those of the unoccupied orbitals in blue.

unusually low energy emission of the copper−tin−tellurium cluster, which is centered at ∼1280 nm (∼0.97 eV) and tails up to ∼1700 nm.

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EXPERIMENTAL SECTION

Synthesis. Standard Schlenk techniques were employed throughout the syntheses using a double-manifold vacuum line with highpurity dry nitrogen (99.9994%) and an MBraun glovebox with highpurity dry argon (99.9990%). The solvents Et2O (diethyl ether), thf (tetrahydrofuran), and toluene were dried over sodium-benzophenone and distilled under nitrogen. CuCl obtained from Sigma-Aldrich was subsequently washed with HCl, CH3OH, and diethyl ether to remove traces of CuCl2 and dried under vacuum. PhSnCl3 obtained from Aldrich or Alfa Aesar was distilled under nitrogen prior to use. CuO(CO)CH3,28 S(SiMe3)2, Se(SiMe3)2, and Te(SiMe3)2,29 and PPh2Et30 were prepared according to literature procedures. [Cu6S6(SnPh)2(PPh2Et)6] (1). PhSnCl3 (0.184 g, 0.61 mmol) was reacted with S(SiMe3)2 (0.44 g, 1.95 mmol) in 10 mL of Et2O for 5 h at room temperature to give a white precipitate. Et2O was then removed under reduced pressure, and the white dry residue was dissolved in 10 mL of toluene. A further 1.5 equiv of S(SiMe3)2 was added to this solution and the solution warmed to 80 °C for approximately 10 min. In a second flask Cu(O)OCCH3 (0.225 g, 1.83 mmol) and PPh2Et (0.78g, 3.65 mmol) were dissolved in 15 mL of Et2O to give a light yellow solution. Both reaction mixtures were cooled to 0 °C, and the solution with the copper acetate phosphine complex was slowly added to the tin−sulfur component to result in the formation of a yellow-orange solution. Yellow crystals of 1 started to grow soon after the stirring was stopped. Crystallization was completed upon storing the solution for one night in a refrigerator followed by filtration (G3) and washing two times with 10 mL of Et2O (yield 445 mg, 65%). Anal. Calcd for C96H100Cu6S6P6Sn2 (2250.75): C, 51.2; H, 4.5; S, 8.6. Found: C, 51.2; H, 4.3; S, 8.4. [Cu6Se6(SnPh)2(PPh2Et)6] (2). Cu(O)OCCH3 (0.225 g, 1.83 mmol) and PPh2Et (0.78 g, 3.65 mmol) were dissolved in 15 mL of Et2O to give a light yellow solution. In a second flask PhSnCl3 (0.184 g, 0.61 mmol) was reacted with Se(SiMe3)2 (0.44 g, 1.95 mmol)) in 10 mL of thf to give a yellow precipitate in a yellow solution. Both reaction mixtures were cooled to −40 °C and combined to give an orange-red solution with a yellow precipitate. Further stirring and warming to 0 °C resulted in the formation of an almost clear red solution. Stirring was then stopped, and the reaction solution was kept in a refrigerator to give orange-red crystals of 2 which were filtered (G3) after 2 days (yield 678 mg, 88%). Anal. Calcd for C96H100Cu6Se6P6Sn2 (2532.12): C, 45.5; H, 4.0. Found: C, 45.5; H, 4.0. [Cu6Te6(SnPh)2(PPh2Et)6] (3). Cu(O)OCCH3 (0.225 g, 1.83 mmol), PPh2Et (0.78 g, 3.65 mmol), and PhSnCl3 (0.184 g, 0.61 mmol) were dissolved in 25 mL of toluene to give a clear solution. After the solution was cooled to −70 °C, Te(SiMe3)2 (0.55 g, 1.95 mmol) was added. The reaction solution quickly changed color from pale yellow to orange and then to red. Upon standing in the refrigerator at around 4 °C dark lilac crystals of 3 started to form after one night from an intense dark red solution. Those were filtered (G3) after 4 days (yield 598 mg, 69.5%). Anal. Calcd for C96H100Cu6Te6P6Sn2 (2823.96): C, 40.8; H, 3.6. Found: C, 41.4; H, 3.6. An enhanced percentage of carbon is indicative of a slight amount of remaining toluene solvent molecules in the crystal lattice. Crystallography. Crystals suitable for single-crystal X-ray diffraction were taken directly from the reaction solution of the compound and then selected in perfluoroalkylether oil. Single-crystal X-ray diffraction data of 1−3 were collected using graphitemonochromatised Mo Kα radiation (λ = 0.71073 Å) on a STOE IPDS II (Imaging Plate Diffraction System) instrument. Raw intensity data were collected and treated with the STOE X-Area software, Version 1.39. Data for all compounds were corrected for Lorentz and polarization effects. 9334


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Inorganic Chemistry

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(8) Wang, L.; Wu, T.; Zuo, F.; Zhao, X.; Bu, X.; Wu, J.; Feng, P. Assembly of supertetrahedral T5 copper-indium sulfide clusters into a super-supertetrahedron of infinite order. J. Am. Chem. Soc. 2010, 132, 3283−3285. (9) Xiong, W.-W.; Li, J.-R.; Hu, B.; Tan, B.; Lia, R.-F.; Huang, X.-Y. Largest discrete supertetrahedral clusters synthesized in ionic liquids. Chem. Sci. 2012, 3, 1200−1204. (10) Hirpo, W.; Dhingra, S.; Sutorik, A. C.; Kanatzidis, M. G. J. Am. Chem. Soc. 1993, 115, 1597−1599. (11) Banger, K. K.; Hepp, A. F.; Harris, J. D.; Jin, M. H.-C.; Castro, S. L. U.S. Patent US 6992202 B1, 2006. (12) Kluge, O.; Biedermann, R.; Holldorf, J.; Krautscheid, H. Organo-Gallium/Indium Chalcogenide Complexes of Copper(I): Molecular Structures and Thermal Decomposition to Ternary Semiconductors. Chem. - Eur. J. 2014, 20, 1318−1331. (13) Pienack, N.; Puls, A.; Näther, C.; Bensch, W. The Layered Thiostannate (dienH2)Cu2Sn2S6: a Photoconductive Inorganic− Organic Hybrid Compound. Inorg. Chem. 2008, 47, 9606−9611. (14) Pienack, N.; Näther, C.; Bensch, W. Two new copper thiostannates synthesised under solvothermal conditions: Crystal structures, spectroscopic and thermal properties of (DBUH)CuSnS3 and (1,4-dabH2)Cu2SnS4. Solid State Sci. 2007, 9, 100−107. (15) Behrens, M.; Ordolff, M.-E.; Näther, C.; Bensch, W.; Becker, K.D.; Guillot-Deudon, C.; Lafond, A.; Cody, J. A. New ThreeDimensional Thiostannates Composed of Linked Cu8S12 Clusters and the First Example of a Mixed-Metal Cu7SnS12 Cluster. Inorg. Chem. 2010, 49, 8305−8309. (16) Zhang, R.-C.; Yao, H.-G.; Ji, S.-H.; Liu, M.-C.; Ji, M.; An, Y.-L. (H2en)2Cu8Sn3S12: a trigonal CuS3-based open-framework sulfide with interesting ion-exchange properties. Chem. Commun. 2010, 46, 4550− 4552. (17) Nayek, H. P.; Massa, W.; Dehnen, S. A Heterometallic, Heterovalent CuI/SnII/IV/S Cluster with an Unprecedented Cu4Sn Core and Stannacyclopentane Units. Inorg. Chem. 2008, 47, 9146− 9148. (18) Hauser, R.; Merzweiler, K. [(PhSnS3)2(CuPPhMe2)6], ein sechskerniger Kupfer(I)-Komplex mit PhSnS3-Liganden. Z. Anorg. Allg. Chem. 2002, 628, 905−906. (19) Fard, Z. H.; Xiong, L.; Müller, C.; Holynska, M.; Dehnen, S. Synthesis and Reactivity of Functionalized Binary and Ternary Thiometallate Complexes [(RT)4S6], [(RSn)3S4]2−, [(RT) 2 (CuPPh 3 ) 6 S 6 ], and [(RSn) 6 (OMe) 6 Cu 2 S 6 ] 4− (R = C2H4COOH, CMe2CH2COMe; T = Ge, Sn). Chem. - Eur. J. 2009, 15, 6595−6604. (20) Halvagar, M. R.; Fard, Z.; Dehnen, S. Directed derivatization of organotin sulfide compounds: synthesis and self-assembly of an SnS backpack-like cage and a CuSnS ternary cluster. Chem. Commun. 2010, 46, 4716−4718. (21) Zhang, W.; Wu, X.; Ebel, M.; Wang, D.; Rehder, D. Molecular assembly of novel hetero-metal clusters: [(O = MoS3Cu2)2(μSn2S6)]4− and [(S = MoS3Cu2)3(μ3-S)2]4−. Inorg. Chem. Commun. 2002, 5, 768−770. (22) Eichhöfer, A.; Jiang, J.; Lebedkin, S.; Fenske, D.; McDonald, D. G.; Corrigan, J. F.; Su, C.-Y. A ternary Cu−Sn−S cluster complex(NBu4)[Cu19S28(SnPh)12(PEt2Ph)3]. Dalton Trans. 2012, 41, 3321−3327. (23) Kühn, M.; Lebedkin, S.; Weigend, F.; Eichhöfer, A. Optical properties of trinuclear metal chalcogenolate complexes − room temperature NIR fluorescence in [Cu2Ti(SPh)6(PPh3)2]. Dalton Trans. 2017, 46, 1502−1509. (24) Shannon, R. D. Revised Effective Ionic Radii and Systematic Studies of Interatomie Distances in Halides and Chaleogenides. Acta Crystallogr., Sect. A: Cryst. Phys., Diffr., Theor. Gen. Crystallogr. 1976, 32, 751−767. (25) Atkins, P. W.; Overton, T. L.; Rourke, J. P.; Weller, M. T.; Armstrong, F. A. Shriver and Atkins’s Inorganic Chemistry, 5th ed.; W. H. Freeman: New York, 2010; p 498. (26) Allred, A. L.; Rochow, E. G. J. J. Inorg. Nucl. Chem. 1958, 5, 264−268.

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.7b01495. Measured and simulated X-ray powder patterns and calculated transition energies (PDF) Accession Codes

CCDC 1537209−1537211 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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AUTHOR INFORMATION

Corresponding Author

*A.E.: tel, 49-(0)721-608-26371; fax, 49-(0)721-608-26368; email, [email protected]. ORCID

Andreas Eichhöfer: 0000-0002-3412-6280 Florian Weigend: 0000-0001-5060-1689 Present Address ⊥

M. Kühn: BASF SE−Materials Molecular Modeling, 67056 Ludwigshafen, Germany. Author Contributions

A.E., synthesis and characterization; S.L., M. Kehry, and M.M.K., PL and PLE measurements; M. Kühn and F.W., quantum-chemical calculations. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by the Karlsruhe Institut für Technologie (KIT, Campus Nord) and the Helmholtz Research Programme “Science and Technology of Nanosystems (POF-STN). A.E. wishes to thank A. K. Powell for generous support and S. Stahl for the performance of the elemental analysis.

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REFERENCES

(1) Dehnen, S.; Melullis, M. A coordination chemistry approach towards ternary M/14/16 anions. Coord. Chem. Rev. 2007, 251, 1259− 1280. (2) Mitchell, K. In Solar Cells and Their Applications; Partain, L., Ed.; Wiley: New York, 1995; pp 185−210. (3) Contreras, M. A.; Ramanathan, K.; Shama, J. A.; Hasoon, F.; Young, D. L.; Egaas, B.; Noufi, R. Diode Characteristics in State-ofthe-Art ZnO/CdS/Cu(In1−xGax)Se2 Solar Cells. Prog. Photovoltaics 2005, 13, 209−216. (4) Hirpo, W.; Dhingra, S.; Kanatzidis, M. G. Synthesis and structure of the first Indium-Copper cluster, [Cu6In3(SEt)l6]− and its possible relevance to CuInS2. J. Chem. Soc., Chem. Commun. 1992, 557−559. (5) Eichhöfer, A.; Fenske, D. Syntheses and structures of new copper(I)−indium(III)−selenide clusters. J. Chem. Soc., Dalton Trans. 2000, 941−944. (6) Tran, D. T. T.; Beltran, L. M. C.; Kowalchuk, C. M.; Trefiak, N. R.; Taylor, N. J.; Corrigan, J. F. Ternary Nanoclusters of CuHgS, CuHgSe, and CuInS. Inorg. Chem. 2002, 41, 5693−5698. (7) Williams, M.; Okasha, R. M.; Nairn, J.; Twamley, B.; Afifi, T. H.; Shapiro, P. J. A Photochemical route to discrete, ternary metal chalcogenide clusters. Chem. Commun. 2007, 3177−3179. 9335


Article

Inorganic Chemistry (27) Eichhöfer, A.; Buth, G.; Kühn, M.; Weigend, F. Luminescence in Phosphine-Stabilized Copper Chalcogenide Cluster MoleculesA Comparative Study. Inorg. Chem. 2015, 54, 9413−9422. (28) Edwards, D. A.; Richards, R. Copper(I) carboxylates: preparations and infrared and mass spectral features. J. Chem. Soc., Dalton Trans. 1973, 2463−2468. (29) Schmidt, H.; Ruf, H. Ü ber die Umsetzung von Organohalogensilanen mit Natriumselenid. Z. Anorg. Allg. Chem. 1963, 321, 270−273. (30) Sasse, K. In Methoden der Organischen Chemie; Thieme Verlag: Stuttgart, Germany, 1963; Band 1, p 32. Kaesz, H. D.; Stone, F. G. J. Org. Chem. 1959, 24, 635−637. (31) X-RED32 1.01, Data Reduction Program; Stoe & Cie, Darmstadt, Germany, 2001. (32) Sheldrick, G. M. SHELXTL PC version 5.1, An Integrated System for Solving, Refining, and Displaying Crystal Structures from Diffraction Data; Bruker Analytical X-ray Systems, Karlsruhe, Germany, 2000. (33) Brandenburg, K. Diamond Version 2.1d; Crystal Impact GbR, 1996−2000. (34) WinXPOW; STOE & Cie, Darmstadt, Germany, 2000. (35) Lebedkin, S.; Arnold, K.; Hennrich, F.; Krupke, R.; Renker, B.; Kappes, M. M. FTIR-luminescence mapping of dispersed single-walled carbon nanotubes. New J. Phys. 2003, 5, 140. (36) TURBOMOLE Version 7.0; TURBOMOLE GmbH, 2015. TURBOMOLE is a development of the University of Karlsruhe and the Forschungszentrum Karlsruhe 1989−2007, TURBOMOLE GmbH since 2007. (37) Furche, F.; Ahlrichs, R.; Hättig, C.; Klopper, W.; Sierka, M.; Weigend, F. Turbomole. WIREs Comput. Mol. Sci. 2014, 4, 91−100. (38) Lee, C.; Yang, W.; Parr, R. G. Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. Phys. Rev. B: Condens. Matter Mater. Phys. 1988, 37, 785−789. (39) Becke, A. D. J. Density-functional thermochemistry. III. The role of exact exchange. J. Chem. Phys. 1993, 98, 5648−5652. (40) Weigend, F.; Ahlrichs, R. Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: Design and assessment of accuracy. Phys. Chem. Chem. Phys. 2005, 7, 3297−3305. (41) Yang, X.-X.; Issac, I.; Lebedkin, S.; Kühn, M.; Weigend, F.; Fenske, D.; Fuhr, O.; Eichhöfer, A. Red-luminescent biphosphine stabilized ‘Cu12S6’ cluster molecules. Chem. Commun. 2014, 50, 11043−11045.

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