Reactions of an Isolable Dialkylstannylene with Carbon Disulfide and

Apr 21, 2016 - om6b00208_si_003.zip (16.34 kB). Citing Articles; Related Content. Citation data is made available by participants in Crossref's Cited-...
0 downloads 10 Views 2MB Size
Download PDF
Article pubs.acs.org/Organometallics

Reactions of an Isolable Dialkylstannylene with Carbon Disulfide and Related Heterocumulenes Chenting Yan, Zheng Xu, Xu-Qiong Xiao, Zhifang Li,* Qiong Lu, Guoqiao Lai, and Mitsuo Kira* Key Laboratory of Organosilicon Chemistry and Material Technology of Ministry of Education, Hangzhou Normal University, Hangzhou, 311121, Zhejiang, People’s Republic of China S Supporting Information *

ABSTRACT: The reaction of isolable dialkylstannylene 1 with an excess amount of CS2 produces an isomeric mixture of 3,3′-distanna-2,2′,4,4′-tetrathiabicyclobutylidene 8 and 3,7-distanna-2,4,6,8-tetrathiabicyclo[3.3.0]oct-1(5)-ene 9 with a ratio depending on the reaction conditions. Compounds 8 and 9 are separated by column chromatography and characterized by NMR spectroscopy and X-ray crystallography. Detailed investigation of the reaction has revealed that the initial product is 8, which isomerizes to 9 irreversibly under the catalytic influence of 1 as a Lewis acid. The above view is supported by the theoretical DFT calculations. Treatment of 1 with ArNCO [Ar = 2,6-iPr2C6H3] affords the corresponding carbamoyl(hydroxyl)stannane 11 via the hydrolysis of the corresponding silaaziridinone formed by the [1 + 2] cycloaddition reaction of 1 with the NC double bond of the isocyanate. Stannylene 1 reacts with ArNCS, giving a mixture of complex products, while 1 does not react with CO2.

■

INTRODUCTION Although many isolable stannylenes have been known to date, most of them are those stabilized electronically by neighboring heteroatom substituents like amino, alkylthio, and alkoxy groups (electronically perturbed stannylenes).1 Since the synthesis of 2,2,5,5-tetrakis(trimethylsilyl)-1-stannacyclopentane-1,1-diyl (1) as the first isolable monomeric dialkylstannylene in 1991,2 much attention has been focused on the synthesis and spectroscopic properties of various least electronically perturbed stannylenes such as diarylstannylenes 23 and 34 (Chart 1) and those with other aryl-, alkyl-, and silyl-substituents (electronically unperturbed stannylenes).1 However, the reactions of these unperturbed stannylenes have been studied to a much lesser extent compared with those of the perturbed stannylenes. In 1993, Saito, Tokitoh, and Okazaki had found that stannylene 2 reacts with carbon disulfide to give an unsymmetrically substituted tetrathioalkene 4, which is transformed to the symmetrically substituted tetrathioethylene 5 by releasing CS2 upon heating (eq 1).5 Tetrathioethylenes 4 and 5 have been proposed to form via rather unusual cyclic carbene A as shown in Scheme 1. In contrast, Weidenbruch et al. have reported that more sterically congested diarylstannylene 3 reacts with CS2 to yield completely different products, 6 and 7, by the stepwise insertion of CS2 into the Sn−C bond of 3 (eq 2);6 it has been reported © 2016 American Chemical Society

recently that some diaminostannylenes undergo similar CS2 insertion into the Sn−N bonds of the stannylenes.7

The reactions of diarylstannylene 2 with CS2 are interesting not only mechanistically but also as a one-pot synthesis of electronically interesting tetrathioethylenes, prompting us to investigate the reactions of isolable dialkylstannylene 1 with CS2 and related heterocumulenes.8 In contrast to the results of the reactions of 2 with CS2, the reaction of 1 with CS2 afforded a mixture of 3,3′-distanna-2,2′,4,4′-tetrathiabicyclobutylidene 8 and 3,7-distanna-2,4,6,8-tetrathiabicyclo[3.3.0]oct-1(5)-ene 9 with a ratio depending on the reaction conditions (eq 3).9 Detailed mechanisms of the reaction of 1 with CS2 and the irreversible isomerization of 8 into 9 are mainly discussed in this paper. Received: March 15, 2016 Published: April 21, 2016 1323

DOI: 10.1021/acs.organomet.6b00208 Organometallics 2016, 35, 1323−1328

Article

Organometallics Chart 1. Structural Formulae of Isolable Stannylenes 1−3

Scheme 1. Proposed Mechanism for the Reaction of Stannylene 2 with CS2

Figure 1. Molecular structure of 8. Hydrogen atoms are omitted for clarity. Thermal ellipsoids are shown at the 30% probability level. Selected bond lengths (Å) and angles (deg): C1−C2 = 1.320(8), S1−C1 = 1.779(6), S2−C1 = 1.784(6), S3−C2 = 1.784(6), S4−C2 = 1.775(6), Sn1−S1 = 2.424(16), Sn1−S2 = 2.433(16), Sn2−S3 = 2.435(15), Sn2−S4 = 2.422(17), Sn1−C3 = 2.185(5), Sn1−C6 = 2.179(6), Sn2−C7 = 2.170(6), Sn2−C10 = 2.160(5); C6−Sn1−C3 = 93.8(2), C3−Sn1−S1 = 119.76(16), C6−Sn1−S2 = 121.70(18), S1−Sn1−S2 = 76.59(5), S4−Sn2−S3 = 76.77(5), C1−S1−Sn1 = 83.80(18), C1−S2−Sn1 = 83.5(2), C2−S3−Sn2 = 83.08(18), C2−S4− Sn2 = 83.63(19), C2−C1−S1 = 122.1(5), C2−C1−S2 = 122.5(5), S1− C1−S2 = 115.4(3), C1−C2−S4 = 121.9(5), C1−C2−S3 = 122.2(5), S4−C2−S3 = 115.9(3), C4−C3−Sn1 = 97.3(4).

■

RESULTS AND DISCUSSION Reaction of Stannylene 1 with CS2. The reaction of an excess amount of CS2 with dialkylstannylene 1 in hexane at room temperature gave a mixture of two products 8 and 9 with a ratio depending on the reaction time; the ratio was 7:3 after 1 h and 1:4 after 12 h when monitored by GC. The two products were separated using preparative silica column chromatography and fully characterized as 8 and 9 (eq 3) with the isolated yields of 17% and 70%, respectively, by multinuclear NMR spectroscopy, MALDI-TOF-MS, and finally single-crystal X-ray diffraction studies. The dependence of the ratio of 8/9 on the reaction time suggests that the initial product of the reaction is 8, which isomerizes to 9. The reaction of a 1:1 molar ratio mixture of 1 and CS2 in hexane for 4 h gave solely 9, as monitored by 119Sn NMR spectroscopy. The details of the mechanisms of the reaction of 1 with CS2 as well as the rearrangement from 8 to 9 will be discussed in later sections. Because both 8 and 9 are highly symmetric with the symmetry group of D2h and indistinguishable to each other by solely NMR spectroscopy, they are identified finally by X-ray crystallography (vide infra). Typically, in the 1H NMR spectra, a single peak is found at 0.22 and 0.19 ppm, for 8 and 9, respectively. One 13C NMR signal for unsaturated carbons of 8 and 9 is observed at 117.7 and 120.4 ppm; these are in accordance with those of compound 5 (δ 117.0 ppm)5 and a distannatetrathiobicyclo[3.3.0]octene reported by Růzǐ čka et al. (117.7 ppm).9 A 119Sn NMR signal appears at 116 and 252 ppm for 8 and 9, respectively. The molecular structure of 8 determined by X-ray singlecrystal analysis is shown in Figure 1 together with pertinent structural parameters. The C1−C2 bond length [1.320(8) Å] of 8 is a little shorter than typical CC bond lengths but may be reasonable for this ring system.10 Four sulfur atoms (S1, S2, S3, and S4) are coplanar with two alkene carbons (C1 and C2) expectedly. The bond lengths of Sn−S bonds ranging between 2.422(17) and 2.435(15) Å are similar to those of compound 4.5 The S1−Sn1−S2 and S3−Sn2−S4 planes are almost perpendicular to the Sn1−C3−C6 and Sn2−C7−C10 planes with the

dihedral angles of 86.9° and 86.4°, respectively. The Sn1S1S2 and Sn2S3S4 planes are slightly bent from the alkene plane with the dihedral angles of 12.0° and 9.7°, respectively, and are on the same side of the alkene plane. Compound 9 crystallizes in the P1̅ space group. The unit cell contains two independent, but chemically similar, asymmetric units. One of them is shown in Figure 2. It has a crystallographic inversion center at the center of the CC double bond. The C(1)−C(1A) bond length [1.346(6) Å] is slightly longer than that in 8 but close to typical alkene CC bond distances.10 Similar structural parameters have been reported for the related tetrathioethylene.9 The bent angle between Sn(1)−S(1)−S(2A) and S4C2 planes is 26.8 o, which makes the bicyclo[3.3.0]octane ring chairlike. Reactions of Stannlylene 1 with ArNCO, ArNCS, and CO2. When dialkylstannylene 1 was treated with an equimolar amount of 2,6-di(isopropyl)phenylisocyanate 10 at room temperature in hexane, carbamoyl(hydroxyl)stannane 11 was obtained in 65% isolated yield (eq 4). The product 11 would be formed by the hydrolysis of the highly strained 2-stannadiaziridin3-one B formed via the [1 + 2] cycloaddition of 1 with the CN bond of 10 (eq 4); no experimental evidence for B was obtained. The structure of 11 was fully characterized by 1H, 13C, and 119Sn NMR spectroscopies and finally X-ray crystallography (Figure 3).

1324

DOI: 10.1021/acs.organomet.6b00208 Organometallics 2016, 35, 1323−1328

Article

Organometallics

Figure 2. Molecular structure of 9. Hydrogen atoms are omitted for clarity. Thermal ellipsoids are shown at the 30% probability level. Selected interatomic distances (Å) and angles (deg): Sn1−C2 = 2.173(3), Sn1−C5 = 2.178(3), Sn1−S2A = 2.423(9), Sn1−S1 = 2.426(8), S1−C1 = 1.767(3), S2−C1 = 1.775(3), S2−Sn1A = 2.423(8), C1−C1A = 1.346(6); C2−Sn1−C5 = 93.75(11), C2−Sn1−S2A = 120.39(10), C5−Sn1−S2A = 117.11(9), C2−Sn1−S1 = 116.59(9), C5−Sn1−S1 = 122.82(9), S2A−Sn1−S1 = 88.90(3), C1−S1−Sn1 = 96.39(10), C1−S2−Sn1A = 96.78(10), C1A−C1−S1 = 126.2(3), C1A−C1−S2 = 124.5(3), S1−C1−S2 = 109.31(15), C3−C2−Sn1 = 98.20(19), C4−C5−Sn1 = 97.94(18).

Mechanistic Study. The Reaction of 1 with CS2. The reaction mechanism would be worth discussing more in detail because the products are remarkably different from those of the reactions of CS2 with 2 (eq 1) and 3 (eq 2) reported by Okazaki et al.5 and Weidenbruch et al.6 An intuitively plausible pathway of the reaction of 1 with CS2 would be as shown in Scheme 2. The cyclic dithiocarbene G would be formed via directly from the initial stannylene-CS2 complex E (Path A) or the intramolecular rearrangement of thiastanniranethione F produced by the cyclization of E (Path B). The dimerization of carbene G gives the corresponding alkene 8, which isomerizes to 9. To differentiate the above mechanisms, the Paths A and B were traced for the reaction of model stannylene, Me2Sn: (1′), with CS2 using theoretical calculations at the B3LYP/6-31G(d,p) (C, H, and S)-LanL2DZ (Sn) level;14 for the model reaction with R = Me, the species corresponding to E, F, G, 8, and 9 in Scheme 2 are labeled as E′, F′, G′, 8′, and 9′. The potential energy profile and the free energies of the located stationary points are given in Figure 4 and Table S2, as calculated relative to those of the (1′ + CS2) system. For Path A, the energy and structure of the transition state between E′ and G′ (TS2) was located with the very close structural parameters and energy to G′.15 For Path B, the transition state for the formation of F′ from E′ was located as TS1, but that of G′ from F′ was not observed. The results suggest that the key cyclic carbene G′ would be formed directly from E′, while E′ may be equilibrated with F′. Dimerization of G′ to 8′ would be barrierless. The high activation energy for the process from E′ to G′ may explain why the reaction pathways of 1, 2, and 3 toward CS2 are very different to each other. Thus, there may be three competitive pathways from E: (1) the insertion of another CS2, giving A (Scheme 1),6 (2) an aryl migration leading to 67 (eq 2), and (3) the process giving G (Scheme 2). Less sterically hindered E (E′′, R2Sn = ArAr′Sn) may accept another CS2 to give the corresponding A (Scheme 1), while more hindered E (E‴, R2Sn = Ar”2Sn) may prefer the aryl migration (eq 2). Neither an approach of an extra CS2 nor substituent migration from E would be sterically feasible for stannylene 1. Rearrangement of 8 to 9. There have been very few rearrangements related to that from 8 to 9 reported. The acidcatalyzed rearrangement of carbon bicyclobutylidene to the corresponding bicyclo[3.3.0]octene (BCB/BCO rearrangement) has long been known.16 A silicon version of the BCB/BCO rearrangement has been proposed during the synthesis of a

Figure 3. Molecular structure of 11. Hydrogen atoms are omitted for clarity. Thermal ellipsoids are shown at the 30% probability level. Selected interatomic distances (Å) and angles (deg): Sn1−O2 = 1.998(2), Sn1−C2= 2.177(3), Sn1−C5 = 2.181(3), Sn1−C1 = 2.208(3), N1−C1 = 1.352(4), N1−C18 = 1.446(4), O1−C1 = 1.211(4); O2−Sn1−C2 = 115.38(12), O2−Sn1−C5 = 114.20(11), C2−Sn1−C5 = 93.45(12), O2−Sn1−C1 = 92.70(11), C2−Sn1−C1 = 119.07(12), C5−Sn1−C1 = 123.87(12), C1−N1−C18 = 122.9(3), O1−C1−N1 = 123.3(3), O1−C1−Sn1 = 123.7(2), N1−C1−Sn1 = 113.0(2), C4−C5−Sn1 = 97.23(19).

Dialkylstannylene 1 reacts with isothiocyanate 12 but gives a mixture of unidentified products. Stannylene 1 does not react with carbon dioxide. The reaction modes are remarkably different from those of the reactions of the corresponding silylene 1311,12 with these heterocumulenes, while the reason remains to be elucidated. As previously reported,13 the reactions of dialkylsilylene 13 with isocyanate 10 and isothiocyanate 12 give 14 and 15, respectively, probably via strained intermediate C (eq 5). Silylene 13 reacts with CO2, giving silanol 16, suggesting the formation of D. A complex mixture was obtained during the reaction of 13 with CS2. 1325

DOI: 10.1021/acs.organomet.6b00208 Organometallics 2016, 35, 1323−1328

Article

Organometallics Scheme 2. Two Pathways Proposed for the Reaction of Dialkylstannylene 1 with CS2

Figure 4. Reaction pathway of 1′ + CS2. Reaction and activation free energies (ΔG in kcal mol−1) are given in italics.

persilabicyclo[3.3.0]octene by the reduction of the corresponding 1,1-dichlorocyclotetrasilane.17 The rearrangement of 8 to 9 was not observed when a C6D6 solution of pure 8 in a sealed NMR tube was kept at room temperature; even when the solution was kept at 100 °C for 48 h, only 9% of 9 was formed (eq 7). On the other hand, when a small amount of 1 (20%) was added to a solution of 8 in C6D6, the facile rearrangement occurred at room temperature, giving 9 quantitatively after 24 h. When BF3 (10 mol %), a stronger Lewis acid, was used instead of 1, the rearrangement of 8 to 9 was much more facile, completing almost within 30 min. In accord with the above mechanism, when the time course of the intensity ratio of 8/(8 + 9) in benzene-d6 in the presence of 5% of 1 was monitored 119Sn NMR spectroscopically at 10 °C, the ratio obeyed the first-order kinetics with the rate constant of 1.4 × 10−6 s−1; see the SI for the details. In conclusion, isolable dialkylstannylene 1 reacts with CS2 at room temperature, giving initially distannatetrathiabicyclobutylidene 8 and then rearranges to its isomer 9 irreversibly, and hence, the product ratio 8/9 depends on the reaction times and the initial ratio of 1/CS2. The rearrangement of pure 8 does not occur at room temperature, but it is catalyzed by a Lewis acid like 1 and BF3. The rearrangement is similar to the acid-catalyzed carbon bicyclobutylidene/bicyclo[3.3.0]octene rearrangement but is suggested to be prompted by the coordination of the acid to a sulfur of 8. The reaction of 1 with ArNCO undergoes [1 + 2] cycloaddition of a centered silicon with the CN bond rather than the CO bond of ArNCO, in contrast to the corresponding silylene reacting with the same isocyanate via the CO bond addition of the silylene.

The irreversible rearrangement of 8 to 9 is in good accord with their relative energies as calculated by DFT calculations at the B3LYP/6-31G(d,p) (C, H, and S) - LanL2DZ (Sn).14 As shown in Figure 4, 8′ is less stable than 9′ with the free energy difference of 13.3 kcal/mol. The calculations for real 8 and 9 have revealed similar relative stability with the energy difference of 13.0 kcal/mol.14 The rearrangement of 8 to 9 is evidently catalyzed by Lewis acids, proceeding as shown in eq 8; the mechanism seems to be different from that for the carbon BCB/ BCO rearrangement, where the acidic proton is suggested to add to an alkene carbon. As proposed for the 1,3-dithiolane-todihydro-1,4-dithiin rearrangement,18 an acid (LA) coordinates initially to a sulfur atom of 8, giving the zwitterion H, prompting ring opening to I. A successive attack of a vicinal sulfur atom to the tin cation accompanied by the four-membered ring opening gives J. Then, the tin cation of J is attacked by the sulfur coordinated by LA to produce 9 together with the LA released (eq 8).18

■

EXPERIMENTAL SECTION

All synthetic experiments were performed under argon or nitrogen in a standard vacuum system unless otherwise noted. 1H (400 MHz), 1326

DOI: 10.1021/acs.organomet.6b00208 Organometallics 2016, 35, 1323−1328

Article

Organometallics 13

C (100 MHz), and 119Sn (187 MHz) NMR spectra were recorded with tetramethylsilane as an external standard on a BRUKER AV-400 MHz instrument. GC−MS spectra were measured with an Agilent 7890a gas chromatography instrument coupled to an Agilent 5975c mass spectrometer. Mass spectra were measured with a Bruker Daltonics Autoflex II TM MALDI-TOF spectrometer. High-resolution MS was measured on a Thermo Scientific LTQ Orbitrap XL spectrometer. Elemental analyses were performed on a VARIO EL-III instrument. Melting points are uncorrected. Stannlylene 1 was prepared according to the literature procedures.2 Stannlylene 1 and other air-sensitive materials were handled in an MBraun glovebox. The full 1H, 13C, and 119Sn NMR spectra of all new compounds (8, 9, and 11) are provided in the Supporting Information (SI). The Reaction of Stannlylene 1 with CS2. When carbon disulfide (160 mg, 2.10 mmol) was added dropwise into a hexane (5 mL) solution of stannlylene 1 (100 mg, 0.216 mmol) at room temperature, the color of the reaction mixture turned quickly from red to green, and 1 h later, to yellow. When monitored by GC, two products were detected with a ratio of 7:3 and the ratio changed to 1:4 after 12 h. Removal of the solvent under vacuum and then preparative silica column chromatography gave pure 8 and 9 separately in the yield of 17% and 70%, respectively. They were fully characterized by multinuclear NMR spectroscopy, MALDI-TOF-MS in solution, and single-crystal X-ray diffraction studies in the solid state. 8: red crystals (20 mg, 17%); mp: 237−238.5 °C; 1H NMR (400 MHz, CDCl3) δ 2.15 (s, 8H), 0.22 (s, 72H); 13C NMR (100 MHz, CDCl3) δ 117.7, 32.6, 21.6, 3.2; 119 Sn NMR (187 MHz, CDCl3): δ 116.2; MALDI-TOF-MS m/z Calcd for 12C341H8032S428Si8120Sn2: 1080; Found: 1080;19 Anal. Calcd for C34H80S4Si8Sn2: C, 37.84; H, 7.47; S, 11.88. Found: C, 37.81; H, 7.51; S, 11.84. 9: yellow crystal (82 mg, 70%); mp: 352−353 °C; 1H NMR (400 MHz, CDCl3) δ 2.18 (s, 8H), 0.19 (s, 72H); 13C NMR (100 MHz, CDCl3) δ 120.4, 33.0, 23.0, 3.5; 119Sn NMR (187 MHz, CDCl3) δ 252.0; MALDI-TOF-MS m/z Calcd for 12C341H8032S428Si8120Sn2: 1080; Found: 1080;19 Anal. Calcd for C34H80S4Si8Sn2: C, 37.84; H, 7.47; S, 11.88. Found: C, 37.88; H, 7.43; S, 11.83. The Reaction of Stannlylene 1 with ArNCO. A hexane solution of isocyanate 10 (0.26g, 1.3 mmol) was added dropwise into stannlylene 1 (0.25g, 0.54 mmol) in hexane (10 mL) at room temperature. The reaction mixture was allowed to stir for 12 h. Then, the solvent was removed under vacuum. The residue was dissolved in n-pentane. Colorless crystals of 11 formed upon cooling the solution to −40 °C for 1 week. 11: White solid (422 mg, 65%); mp: 433−434 °C; 1 H NMR (400 MHz, CDCl3) δ 8.86 (s, 1H), 7.15−7.17(m, 3H), 3.13− 3.19(m, 2H), 2.21−2.30 (m, 4H), 1.20 (d, J = 8 Hz, 12H), 0.61 (s, 1H), 0.25 (s, 18H), 0.23 (s, 18H); 13C NMR (100 MHz, CDCl3) δ 184.2, 145.6, 132.3, 128.2, 123.3, 33.5, 29.1, 23.7, 20.8, 3.6, 3.3; 119 Sn NMR (187 MHz, CDCl3) δ 62.3. HRMS m/z [M + Na]+ Calcd for C29H59NNaO2Si4Sn: 708.2539; Found: 708.2531; Anal. Calcd for C29H59NO2Si4Sn: C, 50.86; H, 8.68; N, 2.05; O, 4.67. Found: C, 50.82; H, 8.70; N, 2.01; O, 4.62. X-ray Structure Determination. Single crystals of 8, 9, and 11 suitable for X-ray analysis were obtained by the recrystallization from hexane. The X-ray diffraction data were collected on a Bruker Smart Apex CCD diffractometer with graphite monochromated Mo−Kα radiation (λ = 0.71073 Å) using the ω-2θ scan mode. The structures were solved by direct methods and refined on F2 by full-matrix leastsquares methods using SHELX-2000.20 Crystal and refinement data for 8, 9, and 11 are described in the SI. The supplementary crystallographic data for 8, 9, and 11 are deposited with CCDC; the Nos. are 1432785, 1432786, and 1432787, respectively. DFT Calculations. All calculations were performed on an SGI Altix 450 server using the Gaussian 03 package.14 Geometry optimizations of all stationary points were performed by using the DFT method at the B3LYP/6-31G(d,p) (C, H, and S atoms)- LanL2DZ (Sn) level.

■

■

X-ray crystallographic data and NMR spectra of 8, 9, and 11, theoretical details, and experimental details for the rearrangement of 8 to 9 (PDF) Text file of all computed molecule Cartesian coordinates in .xyz format for convenient visualization (XYZ) Crystallographic data for 8, 9, and 11 (ZIP)

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected] (Z.L.). *E-mail: [email protected] (M.K.). Notes

The authors declare no competing financial interest.

■ ■

ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China (Grant Nos. 21472032 and 21101050). REFERENCES

(1) For recent reveiws of stannylenes and related heavy carbenes, see: (a) Lee, V. Ya.; Sekiguchi, A. Organometallic Compounds of LowCoordinate Si, Ge, Sn, and Pb: From Phantom Species to Stable Compounds; John Wiley & Sons: Chichester, U.K., 2010. (b) Mizuhata, Y.; Sasamori, T.; Tokitoh, N. Chem. Rev. 2009, 109, 3479−3511. (c) Barrau, J.; Rima, G. Coord. Chem. Rev. 1998, 178−180, 593−622. (d) Lappert, M. F. Main Group Met. Chem. 1994, 17, 183−208. (e) Neumann, W. P. Chem. Rev. 1991, 91, 311−344. (f) Lappert, M. F.; Rowe, R. S. Coord. Chem. Rev. 1990, 100, 267−292. (2) Kira, M.; Yauchibara, R.; Hirano, R.; Kabuto, C.; Sakurai, H. J. Am. Chem. Soc. 1991, 113, 7785−7787. (3) Tokitoh, N.; Saito, M.; Okazaki, R. J. Am. Chem. Soc. 1993, 115, 2065−2066. (4) Weidenbruch, M.; Schlaefke, J.; Schäfer, A.; Peters, K.; von Schnering, H. G.; Marsmann, H. Angew. Chem., Int. Ed. Engl. 1994, 33, 1846−1848. (5) Saito, M.; Tokitoh, N.; Okazaki, R. Organometallics 1995, 14, 3620−3622. (6) Weidenbruch, M.; Grobecker, U.; Saak, W.; Peters, E.-M.; Peters, K. Organometallics 1998, 17, 5206−5208. (7) (a) Stewart, C. A.; Dickie, D. A.; Parkes, M. V.; Saria, J. A.; Kemp, R. A. Inorg. Chem. 2010, 49, 11133−11141. (b) Stewart, C. A.; Dickie, D. A.; Tang, Y.; Kemp, R. A. Inorg. Chim. Acta 2011, 376, 73−79. (c) Stewart, C. A.; Dickie, D. A.; Moasser, B.; Kemp, R. A. Polyhedron 2012, 32, 14−23. (8) Some interesting reactions of stanylene 1 have been reported: (a) Kira, M.; Ishida, S.; Iwamoto, T.; Yauchibara, R.; Sakurai, H. J. Organomet. Chem. 2001, 636, 144−147. (b) Iwamoto, T.; Masuda, H.; Ishida, S.; Kabuto, C.; Kira, M. J. Am. Chem. Soc. 2003, 125, 9300−9301. (c) Kira, M.; Ishida, S.; Iwamoto, T. Chem. Rec. 2004, 4, 243−253. (d) Kavara, A.; Cousineau, K. D.; Rohr, A. D.; Kampf, J. W.; BanaszakHoll, M. M. Organometallics 2008, 27, 1041−1043. (e) Kavara, A.; Kampf, J. W.; Banaszak-Holl, M. M. Organometallics 2008, 27, 2896− 2897. (f) Kavara, A.; Boron, T. T., III; Ahsan, Z. S.; Banaszak-Holl, M. M. Organometallics 2010, 29, 5033−5039. (g) Kavara, A.; Kheir, M. M.; Kampf, J. W.; Banaszak-Holl, M. M. J. Inorg. Organomet. Polym. Mater. 2014, 24, 250−257. (h) Schäfer, A.; Saak, W.; Haase, D.; Müller, T. J. Am. Chem. Soc. 2011, 133, 14562−14565. (9) A bicyclic tetrathioethylene with the same skeletal structure has been obtained by the reaction of a C,N-chelated stannylene with CS2 in the presence of sulfur, and the structure was characterized by X-ray crystallography: Padĕlková, Z.; Císařová, I.; Nechaev, M. S.; Růzǐ čka, A. J. Organomet. Chem. 2009, 694, 2871−2874. (10) A shorter CC bond length of 8 than that of 9 was reproduced by the B3LYP/6-31G(d,p)-LanL2DZ level calculations, while the difference is smaller than that found experimentally; the calculated CC bond lengths for 8 and 9 are 1.345 and 1.354 Å. The tendency was

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.organomet.6b00208. 1327

DOI: 10.1021/acs.organomet.6b00208 Organometallics 2016, 35, 1323−1328

Article

Organometallics reproduced for the model compounds with R = Me in eq 3 (8′ and 9′); the lengths are 1.343 and 1.355 Å. (11) Kira, M.; Ishida, S.; Iwamoto, T.; Kabuto, C. J. Am. Chem. Soc. 1999, 121, 9722−9723. (12) For reviews on dialkylsilylene 13, see: (a) Kira, M. J. Organomet. Chem. 2004, 689, 4475−4488. (b) Kira, M.; Iwamoto, T.; Ishida, S. Bull. Chem. Soc. Jpn. 2007, 80, 258−275. (c) Kira, M. Chem. Commun. 2010, 46, 2893−2903. (d) Kira, M. J. Chem. Sci. 2012, 124, 1205−1215. (13) Liu, X.; Xiao, X.-Q.; Xu, Z.; Yang, X.; Li, Z.; Dong, Z.; Yan, C.; Lai, G.; Kira, M. Organometallics 2014, 33, 5434−5439. (14) The DFT calculations were performed with the Gaussian 03 program package. See the Supporting Information for the calculation details and full reference of Gaussian 03. (15) A possible direct formation of G′ complex E′ has been suggested by an anonymous reviewer. We are grateful for his indication. (16) (a) Finkelshtein, E. S.; Strelchik, B. S.; Vdovin, V. M.; Nametkin, N. S. Dokl. Akad. Nauk SSSR 1975, 220, 131−134; Dokl. Chem. 1975, 220, 36−39. (b) Barton, J. W.; Shepherd, M. K. J. Chem. Soc., Perkin Trans. 1 1987, 1561−1565. (c) Anger, T.; Graalmann, O.; Schröder, H.; Gerke, R.; Kaiser, U.; Fitjer, L.; Noltemeyer, M. Tetrahedron 1998, 54, 10713−10720. (17) (a) Kobayashi, H.; Iwamoto, T.; Kira, M. J. Am. Chem. Soc. 2005, 127, 15376−15377. (b) Iwamoto, T.; Furiya, Y.; Kobayashi, H.; Isobe, H.; Kira, M. Organometallics 2010, 29, 1869−1872. (18) (a) Yoshino, H.; Kawazoe, Y.; Taguchi, T. Synthesis 1974, 1974, 713−715. (b) Jekö, J.; Timár, T.; Jaszberenyi, J. Cs. J. Org. Chem. 1991, 56, 6748−6751. (19) Because 10, 3, 3, 2, and 2 isotopes of Sn, S, Si, C, and H, respectively, may contribute to the spectra, the MULDI-TOF mass spectra of 8 and 9 are very complicated, as shown in the SI. Among many peaks, m/z 1080.6 and 1078.6 peaks were observed as the two highest for both 8 and 9, indicating that the major contributors for the two peaks are 12C341H8032S428Si8120Sn2 and 12C341H8032S428Si8118Sn120Sn, respectively. (20) (a) Picou, C. L.; Stevens, E. D.; Shah, M.; Boyer, J. H. Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 1990, 46, 1148−1150. (b) SMART, SAINT, SADABS, and SHELXTL; Bruker AXS Inc.: Madison, WI, 2000.

1328

DOI: 10.1021/acs.organomet.6b00208 Organometallics 2016, 35, 1323−1328