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Syntheses and Structural Characterization of Mono‑, Di‑, and Tetranuclear Silver Carbone Complexes Tomohito Morosaki, Tsubasa Suzuki, and Takayoshi Fujii* Department of Applied Molecular Chemistry, College of Industrial Technology, Nihon University, Chiba 275-8575, Japan S Supporting Information *

ABSTRACT: Mono-, di-, and tetranuclear silver complexes 1−3 were successfully synthesized and isolated using a bis(chalcogenane)carbon(0) (BChC)-bearing iminosulfane ligand. In these complexes, BChCs exhibit κ2C,N and κ3C,C′,N coordination modes. The molecular structure of [Ag4(BChCs)2](TfO)4 (3) reveals the peculiar electronic structure of BChC, which features two electron lone pairs on the central carbon atom. Furthermore, the structure of 3 provides the first experimental proof that carbones can act as multidentate ligands in multication clusters.

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bis(phosphane)carbon(0) (BPC: A)) as a ligand (Figure 1).8 In this structure, the central carbon of A binds to two AuI atoms,

INTRODUCTION The original reports of the isolation of a free divalent carbon(II) species (carbenes)1 and the first silver(I) Nheterocyclic carbene (NHC) complex reported by Arduengo et al.2 and the continuing investigations provided the foundation for the growing area of silver NHC chemistry.3 The considerable attention given to silver NHC complexes has been attributed to their extensive use in NHC transfer reagents, homogeneous catalysts, and luminescence materials.4 Because NHCs are typically monodentate σ-donor ligands, several attempts have been made to prepare multimetallic silver complexes by augmenting NHCs with different functionalized side chains bearing further donor atoms (e.g., Ccarbene, N, O, and P).5,6 To date, several NHC-stabilized cationic tetranuclear silver clusters have been reported.6 However, because NHC ligands have the ability to donate only two electrons, its possible coordination modes are limited to three-center twoelectron bonds or Ag−σ interactions.5,6 Recently, divalent carbon(0) species (carbones) have been recognized as exhibiting unique bonding and donating characteristics at the central carbon atom. The central carbon atom of carbones CL2 possesses all four valence electrons as two lone pairs and is bonded to the two σ-donor ligands L through donor−acceptor interactions (L→C←L). [The bond description of S−C and Se−C (BiSC, iSSC, and iSSeC) could be considered as polar single bonds and dative bonds. We have chosen the dative bonds because these compounds exhibit unusual features.14 Frenking and Schmidbaur suggested that there is a scope for identifying many examples with such out-ofthe-box ideas, which provide opportunities for refining concepts in chemical bonding.7] An important difference between carbone and carbene is that the former is a four-electron donor while the latter is usually a two-electron donor. The most prominent example of the four-electron-donating ability of carbones is the first structurally characterized C-dimetalated complex A·(AuCl)2 with carbodiphosphorane (also termed © XXXX American Chemical Society

Figure 1. Molecular structures of A−G.

clearly demonstrating that the central carbon donates two electron pairs to two Au centers. Thus, the dimetalation of a central carbon atom has been used as a criterion for the definition of divalent carbon(0) character.9,10 Further theoretical and experimental work has revealed that the σ- and π-lone pairs of carbones can be utilized to bind double-Lewis-acidbearing vacant σ- and π-orbitals.11 Only a small number of multinuclear carbone complexes with additional donor atoms have been described.12,13 Shuh and Peringer et al. reported bi- and tridentate d8−d8 or d8−d10 mixed-metal complexes using a phosphane-functionalized carbone,12 and Alcarazo et al. prepared the first chiral Cu−Au heterobimetallic complex using a supporting ligand in which the usual phenyl ring was replaced with a pyridyl substituent.13 Nevertheless, none of these carbones were applied as a ligand for polymetallic clusters containing more than two metal atoms. Moreover, silver−carbone complexes containing two or more silver atoms bound to the carbone ligand have not been reported. Recently, we reported the syntheses and reactivities of several bischalcogenane-stabilized carbon(0) species (BChCs), includReceived: June 4, 2016

A

DOI: 10.1021/acs.organomet.6b00452 Organometallics XXXX, XXX, XXX−XXX

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than that of B (39.7 ppm). However, signals of 1b and 1c are not observed. The absence of the central carbon resonance is not unusual, and this has been reported for several silver carbone complexes.7a,14b,15,16 The molecular structures of 1a and 1b were determined by single-crystal X-ray diffraction analysis (Figures 2 and 3). Table

ing bis(iminosulfane)carbon(0) (BiSC: B), iminosulfane(sulfane)carbon(0) (iSSC: C), and iminosulfane(selenane)carbon(0) (iSSeC: D) (Figure 1).14 Furthermore, we reported the syntheses of phosphorus- and sulfur-stabilized carbones (iminosulfane(phosphane)carbon(0) (iSPCs: E−G)) and their complexation behavior toward gold(I) and silver(I) (Figure 1).15 Naturally, the synthesis of polymetallic complexes requires ligands with at least two donor centers in close spatial proximity. We speculated that the σ- and π-donating abilities of BChCs and imine nitrogen on the iminosulfane substituent would potentially stabilize silver clusters. Consequently, here, we report the preparation and structural characterization of mono-, di-, and tetranuclear silver complexes stabilized by BChCs.

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RESULTS AND DISCUSSION To test the donating ability of BChCs, we first performed the reaction of B−D with 0.5 equiv of AgTfO in MeOH at room temperature (Scheme 1). The reaction smoothly proceeded Figure 2. Molecular structure of the mononuclear complex [Ag(B)2] in 1a. Hydrogen atoms, TfO anions, and solvent molecules are omitted for clarity.

Scheme 1. Synthesis of Silver Carbone Complexes 1−3

Figure 3. Molecular structure of the mononuclear complex [Ag(C)2] in 1b. Hydrogen atoms and TfO anions are omitted for clarity.

1 shows the selected bond lengths and angles of mononuclear complexes 1a and 1b and the literature values for silver carbone complex [AgA2] and bis(NHC) silver complexes ([Ag(NHC)2]).3c,7a,16 Silver centers in 1a and 1b adopt a slightly distorted linear geometry, being bound to central carbon atoms. C→Ag←C angles of 1 (1a: 177.2°; 1b: 178.8°) are nearly linear, which are similar to that of the silver complex [AgA2] (177.5°) and slightly wider than the mean value for bis(NHC) silver complexes (173.8°).3c The mean values of C→Ag distances in 1 (1a: 2.122 Å; 1b: 2.111 Å) are comparable with those of [AgA2] (2.125 Å)7a,16 and calculated values (2.102 Å),17 but are longer than those of related silver bis(NHC) complexes (2.087 Å).3c The twist angle of the two S→C←S planes in 1a (58.2°) is similar to that of the angle in [AgA2] (66.3°), whereas 1b presents almost coplanar geometry (9.5°).3c,7a,16 One of the two central carbon atoms in 1a exhibits slight pyramidalization, with the sum of the three angles being 349.5°, while the other exhibits almost planar geometry (359.0°). Both central carbon atoms of 1b exhibit

and afforded corresponding mononuclear complexes in good yield (1a: 97%; 1b: 72%; 1c: 78%). The 1H NMR spectra of complexes 1a−c in CDCl3 exhibit characteristic singlets due to N-methyl protons (1a: 2.51 ppm; 1b: 2.28 ppm; 1c: 2.26 ppm), which are shifted to a field higher than those of carbones (B: 2.62 ppm; C: 2.46 ppm; D: 2.60 ppm).14 In the 13C NMR spectra for 1a, the central carbon resonance appears as a broad singlet at 40.0 ppm, which is slightly shifted to a field lower B

DOI: 10.1021/acs.organomet.6b00452 Organometallics XXXX, XXX, XXX−XXX

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Table 1. Selected Bond Lengths (Å) and Angles (deg) of Mono- and Dinuclear AgI Complexes 1a, 1b, 2a, [AgA2], and [Ag(NHC)2] 1a C→Ag SIV→C SII→C SIV−N E→C←E C→Ag←C C→Ag←N′

2.116, 2.127 1.671−1.696 1.536−1.541 114.6, 115.6 177.2

1b 2.111, 1.678, 1.715, 1.544, 105.5, 178.8

2.112 1.679 1.721 1.544 105.8

2a

[AgA2]7a,16

[Ag(NHC)2]3c

2.147 1.666, 1.696

2.115, 2.134

2.087

128.5, 129.1 177.5

173.8

1.527, 1.570 114.7 167.9

is slightly longer compared with 1a. The Ag−Ag′ distance of 2.877 Å indicates an argentophilic bonding interaction (2.53− 3.44 Å).20 The central carbon atom of 2a is more pyramidalized (sum of the three angles: 345.0°) compared with 1a. The C→ Ag←N′ bond angle (167.9°) of 2a is narrower than that of 1a and is comparable to that of the NHC dinuclear silver complex (169.5°).21 Encouraged by these results, we attempted to ascertain whether BChC ligands can be employed as ligands for a polymetallic silver cluster. Gratifyingly, the treatment of B−D with two equivalents of AgTfO in methanol affords desired tetranuclear complexes 3a, 3b, and 3c in 95%, 90%, and 70% yields, respectively. In the 1H NMR spectra, 3a displays broad singlets at 2.61 and 2.66 ppm because of asymmetric N-methyl units, whereas 3b and 3c exhibit singlets (3b: 2.59 ppm; 3c: 2.58 ppm) in CD3CN. In the 13C NMR spectra for 3a and 3b, the carbone resonance appears as a broad singlet at 43.7 and 49.0 ppm, respectively, whereas the central carbon resonance signals of 3c are not observed. Crystals suitable for X-ray crystallography were grown by the slow diffusion of hexane into a solution of 3 in dichloromethane. Complexes 3a−c are tetranuclear complexes consisting of a rhomboidal [Ag4]4+ core surrounded by two carbone ligands and four TfO anions (Figure 5−7). Table 2

slightly distorted planar geometry (354.2° and 354.6°). These values are within the range observed for related silver complexes ([AgA2]: 360.0°; [G2·Ag]: 347.6° and 349.7°).15,16 Having obtained mononuclear complexes, we next examined the donating ability of the imine nitrogen. The reaction of B−D with one equivalent of AgTfO results in corresponding dinuclear complexes 2a−c (2a: 95%; 2b: 66%; 2c: 60%; Scheme 1). The coordination of the nitrogen atom of BChCs to AgI is primarily indicated by the appearance of new singlets for N-methyl protons in the 1H NMR spectra for 2 (2a: 2.74 ppm; 2b: 2.58 ppm; 2c: 2.59 ppm). These signals are significantly shifted downfield compared with those of 1 (Δδ: 2a: +0.25 ppm; 2b: +0.30 ppm; 2c: +0.33 ppm). The central carbon resonances of 2a and 2c appear as broad singlets at 43.1 and 52.7 ppm, respectively, while 2b is not observed in the 13C NMR spectra. The solid-state structure of 2a was confirmed by singlecrystal X-ray diffraction analysis (Figure 4). Selected bond

Figure 4. Molecular structure of the dinuclear complex [Ag(μ-Bκ2N,Ccarbone)]2 in 2a. Hydrogen atoms, TfO anions, and solvent molecules are omitted for clarity. Figure 5. Molecular structure of the tetranuclear complex [Ag2(μ-Bκ3N,Ccarbone,C′carbone)]2 in 3a. Hydrogen atoms and TfO anions are omitted for clarity.

lengths and angles are shown in Table 1. Complex 2a comprises two silver atoms joined by two “CPh2SN” bridges to form an eight-membered heterocyclic ring. Interestingly, carbone ligand B adopts a κ2C,N-coordination mode. The N→ Ag bond distance (2.170 Å) is less than the sum of the covalent radii of nitrogen and silver (2.27 Å).18 This demonstrates the donating ability of imine nitrogen toward the cationic metal center. The coordinated S−N bond (1.570 Å) is within its reported range (1.567−1.628 Å)19 and is longer than that of the free ligand B (1.550 Å).14a The C→Ag distance (2.147 Å)

lists the selected bond lengths and angles of tetranuclear complexes 3a−c and compares them with the literature values of tetranuclear silver complexes H−K consisting of a rhomboidal core stabilized by two-electron-donor ligands, i.e., NHC or an anionic aryl ligand with nitrogen atoms present on side chains (Figure 8).6a,b,d,22 To the best of our knowledge, C

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Figure 6. Molecular structure of the tetranuclear complex [Ag2(μ-Cκ3N,Ccarbone,C′carbone)]2 in 3b. Hydrogen atoms and TfO anions are omitted for clarity.

Figure 8. Structure of tetranuclear silver complexes with NHC or aryl anion ligands H−K.

Each central carbon of carbones B−D symmetrically interacts with two neighboring silver atoms, forming two threemembered rings. The dihedral angles (3a: 79.85°; 3b: 80.95°; 3c: 81.44°) of these three-membered rings are nearly perpendicular to the [Ag4]4+ plane, which are different from those of H−K (which exhibit nearly planar geometry (H: 0°; I: 18.32°; J: 22.94°; K: 31.88°)).6a,b,d,22 The two E→C←S (E = SIV, SII, or SeII) planes are approximately perpendicular to the [Ag4]4+ plane, as indicated by dihedral angles between them (3a: 87.36°; 3b: 88.96°; 3c: 89.94°). Diagonal Ag2−Ag2′ distances (3a: 2.812 Å; 3b: 2.846 Å; 3c: 2.845 Å) are shorter than the four side lengths of the square ring (Ag1−Ag2: 3a: 2.868 Å; 3b: 2.866 Å; 3c: 2.909 Å; Ag1− Ag2′: 3a: 3.177 Å; 3b: 3.222 Å; 3c: 3.222 Å), in contrast to the trend observed in H−K (Table 2).6a,b,d,22 These values indicate argentophilic interactions (2.53−3.44 Å).20 Other diagonal Ag1−Ag1′ distances (3a: 5.361 Å; 3b: 5.394 Å; 3c: 5.439 Å) are significantly longer than those of H−K (Table 2). The Ag1−Ag2−Ag1′ angles of 3 (3a: 124.9°; 3b: 124.6°; 3c: 125.0°) are wider than those of H−K (H: 108.1°; I: 108.0°; J: 115.6°; K: 97.5°). Structural differences between 3 and H−K are most likely because of differences in the electron-donating ability of ligands. Interestingly, the C→Ag bond distances of 3 (3a: 2.193 and 2.228 Å; 3b: 2.187 and 2.192 Å; 3c: 2.174 Å) are comparable to those of silver carbone complexes (2.115−2.221 Å).7a,14b,15,16 These observations are different from those of [Ag4]4+ clusters

Figure 7. Molecular structure of the tetranuclear complex [Ag2(μ-Dκ3N,Ccarbone,C′carbone)]2 in 3c. Hydrogen atoms and TfO anions are omitted for clarity.

complexes 3a−c are the first examples of [Ag4]4+ clusters that are supported by two carbone ligands and adopt a κ3C,C′,N coordination. It is interesting to note that the ratio of ligands and Ag of 3 is 1:2, whereas that of NHC and aryl ligands is 1:1.

Table 2. Selected Bond Lengths (Å) and Angles (deg) of Tetranuclear Ag(I) Complexes 3a−c and H−K

C→Ag1 C→Ag2 N→Ag Ag1−Ag2 Ag1−Ag2′ Ag1−Ag1′ Ag2−Ag2′ Ag1←C→Ag2 C→Ag2←N′ Ag1−Ag2−Ag1′ Ag2−Ag1−Ag2′

3a

3b

3c

H6b

I6d

J6a

K23

2.228 2.193 2.204 2.868 3.177 5.361 2.812 80.9 158.6 124.9 55.1

2.192 2.187 2.188 2.866 3.222 5.394 2.846 81.8 161.7 124.6 55.4

2.174 2.174 2.184 2.909 3.222 5.439 2.845 84.0 161.1 125.0 55.0

2.136 2.348 2.407, 2.427 2.851 2.851 4.618 3.346 78.8

2.204 2.265 2.674 2.820 2.728 4.535 3.293 76.9, 78.2

2.147 2.412 2.360 2.768 2.808 4.719 2.971 72.3, 75.8

2.135−2.168 2.351−2.410 2.489−2.562 2.748, 2.731 2.733, 2.744 4.117 3.613 73.4−74.5

108.1 71.9

108.0 72.0

115.6 64.4

97.5 82.5

D

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3a are similar to those of 2a. These structures indicate that the eight-membered ring structure observed in 2a is retained in the tetranuclear complex.

supported by two-electron-donating ligands such as H−K. Generally, one of the two C→Ag bond distances of twoelectron-donor ligands (such as NHCs and aryl anions in tetranuclear silver clusters) becomes longer (2.261−2.671 Å)6,22 than C→Ag bond distances observed in mononuclear complexes (2.056−2.166 Å)6c because of the Ag−π interactions or three-center two-electron bonding.23 Furthermore, the Ag1←C→Ag2 angles of 3 (3a: 80.9°; 3b: 81.8°; 3c: 84.0°) are wider than those of H−K (H: 78.8°; I: 78.2°; J: 75.8°; K: 74.5°). In the case of 3, the central carbon can donate each silver(I) using two orthogonal lone pairs to make the two C→ Ag σ-coordination bonds. Thus, the two C→Ag bond distances are within the range observed for general C→Ag distances, and the Ag1←C→Ag2 angles are close to 90°. Hence, these arrangements reflect the four-electron-donating ability of BChCs. The two terminal silver atoms Ag1 and Ag1′ are tricoordinated by central carbon and two TfO anions with trigonal planar geometry (Figure 9; sum of the three angles: 3a:

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CONCLUSION We have successfully synthesized mono-, di-, and tetranuclear Ag complexes 1−3. Di- and tetranuclear silver complexes form unique structures with bicyclic and tetracyclic chelate ring systems, respectively. In these complexes, BChCs exhibit κ2C,N and κ3C,C′,N coordination modes. Particularly, the tetranuclear Ag complex 3 not only exhibits the four-electron-donating ability of BChCs but also more importantly provides the first experimental proof of a carbone acting as a multidentate ligand in multication clusters. These complexation behaviors of carbones indicate that the introduction of appropriate σdonor substituents on the ligand enables the formation of multimetallic cluster complexes bearing carbones as novel chelating ligands. These results should be considered as a new approach toward the design of new multinuclear metal− carbone complexes. Further studies aimed at investigating the synthesis and catalytic application of multinuclear transition metal complexes with carbone ligands are currently under way in our laboratory.

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EXPERIMENTAL SECTION

General Considerations. Reagents were purchased reagent grade from commercial suppliers and used without further purification. 1H, 13 C{1H}, 19F{1H}, and 77Se NMR spectroscopies were recorded on a Bruker Avance 500 MHz spectrometer. 1H and 13C{1H} NMR chemical shifts (δ) in CDCl3 are given in ppm relative to Si(CH3)4; coupling constants (J) in Hz. 1H and 13C{1H} NMR chemical shifts (δ) in CD3CN are calibrated to the residual proton resonance of the solvent (CD3CN: δH = 1.94, δC = 1.32). Chemical shifts for 19F{1H} and 77Se NMR spectroscopy were referenced to an external standard (C6H5CF3; δF = −63.7, Me2Se; 0.0). Melting points (mp) were determined with a Yanaco MP-03 instrument. Carbones 1, 2, and 3 were prepared according to the literature.14 Syntheses and Characterization of Compounds. To a solution of carbone in methanol was added 0.5−2.0 equiv of AgTfO. The mixture was protected from light and stirred 3 h. The solvent was removed under reduced pressure. The residue was dissolved in dichloromethane (DCM) and filtered through Celite. Concentration of the filtrate under reduced pressure afforded the desired product. [(BiSC)2Ag]TfO (1a). A 130 mg (0.31 mmol) amount of BiSC and 40.3 mg (0.160 mmol) of AgTfO in 20 mL of methanol were employed (170 mg, 97%). The solid product of 1a suitable for X-ray analysis was recrystallized in benzene/hexane to yield colorless crystals. Mp: 165−166 °C (dec); 1H NMR (400 MHz, CDCl3): δ 2.51 (s, 12H), 7.29−7.33 (m, 16H), 7.41−7.45 (m, 8H), 7.69−7.71 (m, 16H) ppm. 1H NMR (400 MHz, CD3CN): δ 2.50 (s, 12H), 7.31−7.35 (m, 16H), 7.45−7.48 (m, 8H), 7.68−7.70 (m, 16H) ppm. 19 F NMR (470 MHz, CDCl3): δ −78.9 ppm. 13C NMR (100 MHz, CDCl3): δ 30.0, 40.0 (SCS), 122.1 (q, JCF = 320 Hz), 127.7, 129.1, 132.3, 141.4 ppm. Anal. Calcd (%) for C55H52AgF3N4O3S5·0.5C6H6: C, 58.97; H, 4.69; N, 4.74. Found: C, 58.77, H 4.80, N 5.06. [(iSSC)2Ag]TfO (1b). A 82.8 mg (0.20 mmol) amount of iSSC and 25.7 mg (0.10 mmol) of AgTfO in 20 mL of methanol were employed (65 mg, 60%). The solid product of 1b suitable for X-ray analysis was recrystallized in DCM/hexane to yield colorless crystals. Mp: 105−106 °C. 1H NMR (500 MHz, CDCl3): δ 2.28 (s, 6H), 7.32−7.37 (m, 24H), 7.42−7.45 (m, 4H), 7.51−7.52 (m, 4H), 7.88−7.90 (m, 8H) ppm. 13C NMR (126 MHz, CDCl3): δ 29.7, 121.2, (q, JCF = 321 Hz), 127.8, 127.8, 129.3, 130.0, 131.4, 132.4, 139.1, 141.7 ppm. 19F NMR (470 MHz, CDCl 3 ): δ −78.9 ppm. Anal. Calcd (%) for C53H46AgF3N2O3S5·H2O: C, 57.76; H, 4.39; N, 2.54. Found: C, 57.64; H, 4.21; N, 2.56.

Figure 9. Molecular structure of 3a (a) and schematic representation of tetranuclear silver complexes (b) with TfO anions.

359.5°; 3b: 357.9°; 3c: 355.8°). One of the two TfO anions bridges Ag1 and Ag2′ atoms (Ag1−O2: 3a: 2.326 Å; 3b: 2.336 Å; 3c: 2.484 Å; Ag2′−O3: 3a: 2.509 Å; 3b: 2.532 Å: 3c: 2.680 Å), whereas the other is coordinated to Ag1 (Ag1−O1: 3a: 2.315 Å; 3a: 2.263 Å; 3a: 2.267 Å). The N→Ag bond distances (3a: 2.204 Å; 3b: 2.188 Å; 3c: 2.184 Å) of 3 and the Ag2−Ag2′ bond distances (2.812 Å) and C→Ag2←N′ angle (158.6°) of E

DOI: 10.1021/acs.organomet.6b00452 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics [(iSSeC)2Ag]TfO (1c). A 92.2 mg (0.20 mmol) amount of iSSeC and 25.7 mg (0.10 mmol) of AgTfO in 20 mL of methanol were employed (71 mg, 60%). The solid product of 1c was recrystallized in DCM/ hexane to yield a white powder. Mp: 83−84 °C. 1H NMR (500 MHz, CDCl3): δ 2.26 (s, 6H), 7.31 (t, J = 7.5 Hz, 8H), 7.36 (t, J = 7.5 Hz, 8H), 7.45 (t, J = 7.5 Hz, 4H), 7.48 (d, J = 7.5 Hz, 8H), 7.56 (t, J = 7.5 Hz, 4H), 7.84 (d, J = 7.5 Hz, 8H) ppm. 1H NMR (500 MHz, CD3CN): δ 2.49 (s, 6H), 7.33−7.36 (m, 8H), 7.40−7.45 (m, 8H), 7.47−7.50 (m, 8H), 7.55−7.59 (m, 4H), 7.60−7.65 (m, 8H), 7.66− 7.70 (m, 4H). 13C NMR (126 MHz, CD3CN): δ 30.5, 122.2 (q, JCF = 321 Hz), 128.9, 130.0, 131.2, 131.9, 133.6, 135.2, 136.6, 139.7 ppm, the signal of the central carbon was not observed. 19F NMR (470 MHz, CDCl3): δ −78.8 ppm. 19F NMR (470 MHz, CD3CN): δ −80.3 ppm. 77Se NMR (95.4 MHz, CD3CN): δ 558.3 ppm. Anal. Calcd (%) for C53H46AgF3N2O3S3Se2·2H2O: C, 52.44; H, 4.15; N, 2.31. Found: C, 52.64; H, 3.83; N, 2.35. [(BiSC)2Ag2](TfO)2 (2a). A 130 mg (0.31 mmol) amount of BiSC and 80.6 mg (0.31 mmol) of AgTfO in 20 mL of methanol were employed (200 mg, 95%). The solid product of 2a suitable for X-ray analysis was recrystallized in DCM/hexane to yield colorless crystals. Mp: 179−180 °C. 1H NMR (500 MHz, CD3CN): δ 2.74 (s, 12H), 7.37 (t, J = 8.0 Hz, 16H), 7.52 (t, J = 8.0 Hz, 8H), 7.68 (d, J = 8.0 Hz, 16H) ppm. 1H NMR (500 MHz, CD3CN, −40 °C): δ 2.67 (s, 12H), 7.33−7.36 (m, 16H), 7.49−7.52 (m, 8H), 7.58−7.64 (br, 16H) ppm. 13 C NMR (125 MHz, CD3CN): δ 33.6, 43.1 (SCS), 122.2 (q, JCF = 321 Hz), 128.8, 130.5, 130.4, 140.6 ppm. 19F NMR (470 MHz, CDCl3): δ −78.9 ppm. 19F NMR (470 MHz, CD3CN): δ −80.2 ppm. Anal. Calcd (%) for C56H52Ag2F6N4O6S6: C, 48.07; H, 3.75; N, 4.00. Found: C, 48.07; H, 3.75; N, 4.00. [(iSSC)2Ag2](TfO)2 (2b). A 82.8 mg (0.20 mmol) amount of iSSC and 51.4 mg (0.20 mmol) of AgTfO in 20 mL of methanol were employed (88 mg, 66%). The solid product of 2b was recrystallized in DCM/hexane to yield a brown powder. Mp: 105−106 °C. 1H NMR (500 MHz, CDCl3): δ 2.58 (s, 6H), 7.21−7.27 (m, 12H), 7.39−7.40 (m, 8H), 7.64 (t, J = 7.5 Hz, 8H), 7.75 (d, J = 7.5 Hz, 12H) ppm. 1H NMR (500 MHz, CD3CN): δ 2.38 (s, 6H), 7.34−7.49 (m, 26H), 7.52−7.55 (m, 4H), 7.57−7.64 (m, 2H), 7.73−7.83 (m, 8H) ppm. 13C NMR (126 MHz, CD3CN): δ 32.8, 122.2 (q, JCF = 321 Hz), 128.9, 129.4, 131.2, 131.7, 133.6, 135.3, 138.3 ppm, the signal of the central carbon was not observed. 19F NMR (470 MHz, CDCl3): δ −78.8 ppm. 19 F NMR (470 MHz, CD3CN): δ −80.2 ppm. Anal. Calcd (%) for C54H46Ag2F6N2O6S6·0.66CH2Cl2: C, 46.98; H, 3.41; N, 2.00. Found: C, 46.80; H, 3.29; N, 2.09. [(iSSeC)2Ag2](TfO)2 (2c). A 92.2 mg (0.20 mmol) amount of iSSeC and 51.4 mg (0.20 mmol) of AgTfO in 20 mL of methanol were employed (86 mg, 60%). The solid product of 2c was recrystallized in acetone/hexane to yield a brown powder. Mp: 83−84 °C. 1H NMR (500 MHz, CDCl3): δ 2.59 (s, 6H), 7.27 (t, J = 3.5 Hz, 8H), 7.40 (t, J = 7.5 Hz, 4H), 7.51 (t, J = 8.5 Hz, 16H), 7.58 (t, J = 7.5 Hz, 4H), 7.69 (d, J = 7.5 Hz, 8H) ppm. 1H NMR (500 MHz, CD3CN): δ 2.51 (s, 6H), 7.33−7.36 (m, 8H), 7.40−7.44 (8H), 7.47−7.51 (m, 8H), 7.55− 7.58 (m, 4H), 7.59−7.63 (m, 8H), 7.68−7.71 (m, 4H) ppm. 13C NMR (126 MHz, CD3CN): δ 35.7, 52.7 (SeCS), 122.2 (q, JCF = 321 Hz), 129.0, 130.0, 131.3, 131.9, 133.6, 135.3, 136.5, 136.9 ppm. 19F NMR (470 MHz, CDCl3): δ −78.8 ppm. 19F NMR (470 MHz, CD3CN): δ −80.2 ppm. 77Se NMR (95.4 MHz, CD3CN): δ 558.6 ppm. Anal. Calcd (%) for C54H46Ag2F6N2O6S4Se2·(Me)2CO: C, 45.86; H, 3.51; N, 1.88. Found: C, 45.74; H, 3.24; N, 2.08. [(BiSC)2Ag4](TfO)4 (3a). A 44.7 mg (0.10 mmol) amount of BiSC and 51.4 mg (0.20 mmol) of AgTfO in 20 mL of methanol were employed (91 mg, 95%). The solid product of 3a suitable for X-ray analysis was recrystallized in DCM/hexane to yield colorless crystals. Mp: 175−177 °C. 1H NMR (500 MHz, CDCl3): δ 2.65 (s, 12H), 7.36−7.39 (m, 16H), 7.42−7.45 (m, 8H), 7.77−7.79 (m, 16H). 1H NMR (500 MHz, CD3CN): δ 2.61 (s, 6H), 2.66 (s, 6H), 7.33−7.36 (m, 16H), 7.48−7.51 (m, 8H), 7.67−7.69 (m, 16H) ppm. 13C NMR (125 MHz, CDCl3): δ 30.9, 128.0, 129.6, 132.9, 138.2 ppm; the signal of the central carbon was not observed in CDCl3. 13C NMR (125 MHz, CD3CN): δ 34.4, 43.7 (SCS), 122.2 (q, JCF = 321 Hz), 128.9, 130.5, 134.1, 140.0 ppm. 19F NMR (470 MHz, CDCl3): δ −78.8 ppm.

F NMR (470 MHz, CD3CN): δ −80.3 ppm. Anal. Calcd (%) for C58H52Ag4F12N4O12S8: C, 36.41; H, 2.74; N, 2.93. Found: C, 36.76; H, 2.62; N, 3.07. [(iSSC)2Ag4](TfO)4 (3b). A 41.4 mg (0.10 mmol) amount of iSSC and 51.4 mg (0.20 mmol) of AgTfO in 20 mL of methanol were employed (84 mg, 90%). The solid product of 3b suitable for X-ray analysis was recrystallized in DCM/diethyl ether to yield colorless crystals. Mp: 105−106 °C. 1H NMR (500 MHz, CDCl3): δ 2.64 (s, 6H), 7.42 (t, J = 8.0 Hz, 8H), 7.46−7.49 (m, 4H), 7.54 (d, J = 8.0 Hz, 8H), 7.64 (t, J = 7.0 Hz, 8H), 7.69 (t, J = 7.0 Hz, 4H), 8.01 (d, J = 7.0 Hz, 8H) ppm. 1H NMR (500 MHz, CD3CN): δ 2.59 (s, 6H), 7.43− 7.41 (m, 16H), 7.51−7.57 (m, 12H), 7.59−7.63 (m, 4H), 7.68−7.71 (m, 8H) ppm. 13C NMR (126 MHz, CD3CN): δ 35.9, 49.0 (SCS), 122.2 (q, JCF = 321 Hz), 129.0, 129.4, 131.2, 131.7, 133.7, 135.4, 138.1, 142.1 ppm. 19F NMR (470 MHz, CDCl3): δ −78.2 ppm. 19F NMR (470 MHz, CD3 CN): δ −80.2 ppm. Anal. Calcd (%) for C56H46Ag4F12N2O12S8·0.5CH2Cl2: C, 35.76; H, 2.50; N, 1.48. Found: C, 35.73; H, 2.12; N, 1.68. [(iSSeC)2Ag4](TfO)4 (3c). A 46.1 mg (0.10 mmol) amount of iSSeC and 51.4 mg (0.20 mmol) of AgTfO in 20 mL of methanol were employed (68 mg, 70%). The solid product of 3c suitable for X-ray analysis was recrystallized in acetone/diethyl ether to yield colorless crystals. Mp: 159−161 °C. 1H NMR (500 MHz, CDCl3): δ 2.43 (s, 6H), 7.35 (t, J = 7.0 Hz, 8H), 7.43 (t, J = 8.0 Hz, 4H), 7.59 (d, J = 7.5 Hz, 8H), 7.66 (br, 12H), 8.06 (br, 8H) ppm. 1H NMR (500 MHz, CD3CN): δ 2.58 (s, 6H), 7.35−7.48 (m, 14H), 7.54−7.62 (m, 12H), 7.66−7.72 (m, 8H), 7.73−7.77 (m, 6H) ppm. 13C NMR (126 MHz, CD3CN): δ 36.2, 122.2 (q, JCF = 321 Hz), 129.1, 130.0, 131.4, 132.1, 133.8, 135.6, 136.3 ppm; the signal of the central carbon was not observed. 19F NMR (470 MHz, CDCl3): δ −78.4 ppm. 19F NMR (470 MHz, CD3CN): δ −80.2 ppm. 77Se NMR (95.4 MHz, CD3CN): δ 563.7 ppm. Anal. Calcd (%) for C56H46Ag4F12N2O12S6Se2: C, 34.51; H, 2.38; N, 1.44. Found: C, 34.48; H, 2.17; N, 1.48. 19

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ASSOCIATED CONTENT

* Supporting Information S

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.organomet.6b00452. NMR spectra of all new compounds and structural parameters (PDF) Crystallographic data (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 This work was partially supported from the Ministry of Education, Culture, Sports, Science, and Technology of Japan by Grants-in-Aid for Scientific Research(c) (No. 15K05438) and a research fellowship from the Japan Society for the Promotion of Science for Young Scientists (No. 15J05047).

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REFERENCES

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DOI: 10.1021/acs.organomet.6b00452 Organometallics XXXX, XXX, XXX−XXX

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DOI: 10.1021/acs.organomet.6b00452 Organometallics XXXX, XXX, XXX−XXX