J. Am. Chem. SOC.1981, 103, 301 1-3014 by the method of Gastro and Stephens.28 The p-substituted iodobenzenes were all obtained from Pfaltz and Bauer and used without further purification. Iodomesitylenewas prepared from mesitylene, ICI, and ZnC12 by the literature method; mp 31 OC (lit 32 OC)." In all cases the resulting acetylene was recrystallized from methanol or hexanes until no change in melting point was observed. p-ClC6H4CWPh: mp 80.5-81.5 OC (MB 81.5-82 "C); IR(CC1,) 2225 (w), 1605 (sh), 1595 (s), 1495 (s), 1445 (s), 1400 (s), 1090 (s), 1015 (s), 825 (s), 685 (s) cm-I. p CH3C6H4C=CPh: mp 70-71 OC (lit.'' mp 72-74 "C); IR(CC1,) 2215 (W), 1600 (S), 1515 (S), 1487 (S), 1445 (S), 685 (S) cm-I; 'H NMR(C6D6) 8 1.99 (s, 3 H), 6.97 (m, 5 H), 7.50 (m, 4 H). p - M e O C 6 H 4 m P h : mp 57-61 OC (lit.30*3i mp 58-60 "C); IR(CC14) 2210 (w), 1500 (s), 1435 (m), 1242 (s), 1168 (m), 1030 (s), 825 (s) cm-I; 'H NMR(C,D,) 6 3.17 (28) Stephens, R. D.; Castro, C. E. J . Org. Chem. 1963, 28, 3313. (29) Newman, M. S.; Reid, D. E. J . Org. Chem. 1958, 23, 665. (30) Scandiglia, F.; Roberts, J. D. Tetrahedron 1958, 3, 197. (31) Katritzky, A. R.; Boulton, A. J.; Short, D. J. J . Chem. SOC.1960, 1519. (32) Ito, T.; Kirayama, T.; Yamamoto, A. Bull. Chem. SOC.Jpn. 1976, 49, 3250. (33) Keefer, R. M.; Andrews, L. J. J . Am. Chem. Soc. 1956, 78, 5623.
301 1
(s, 3 H), 6.5-7.4 (m, 9 H). p - N o 2 c 6 H 4 m P h :mp 117-118 OC (1km mp 119-120 "C); IR(CC14)2225 (m), 1600 (s), 1528 (s), 1350 (s), 855 (s), 689 (s) cm-I. 2,4,6-C6H2(CH3)3C~CPh: mp 36.5-37 OC (lit.34 36-37 "C); IR(CC1.J 3100-2910 (mult, s), 2210 (m), 1612 (s), 1598 (s), 1495 (S), 850 (S), 685 (s) cm-I; 'H NMR (C6D6) 6 2.10 (S, 3 H), 2.48 (s, 6 H), 6.71 (s, 2 H), 7.0 (m, 3 H), 7.48 (m, 2 H).
Acknowledgment. W e are grateful to Dr. Richard Marsh (California Institute of Technology) for extensive assistance with the X-ray diffraction study. W e also acknowledge the assistance of M r . Rudi Nunlist in the NMR experiments and stimulating correspondence on the mechanism of insertion reactions with Professors H. C. Clark and M. L. H. Green. Financial support for this work was provided by the National Institutes of Health (Grant No. GM-12459). (34) Martelli, P. G.; Spangnolo, P.; Trecco, M. J . Chem. SOC.B 1970, 1413. (35) Pouchert, C. J.; Campbell, "The Aldrich Library of NMR Spectra";
Aldrich Chemical Co.: Milwaukee, WI, 1974; Vol. 1-25 D. (36) Rummens, F. H. A,; Dehaan, J. W. Org. Magn. Reson. 1970,2,351.
A Novel Molybdenum Thiolato Compound, Tetrakis( tert-butylthiolato)molybdenum(IV). Preparation and Crystal and Molecular Structure Sei Otsuka,*la Masato Kamata,IaKen Hirotsu,Iband Taiichi Higuchi*Ib Contribution from the Departments of Chemistry, Faculty of Engineering Science, Osaka University, Toyonaka, Osaka 560,Japan, and the Osaka City University, Sumiyoshiku, Osaka 558. Japan. Received October 27, 1980
Abstract: The new dark red, diamagnetic M O ( ~ - B U Swas ) ~ prepared by treating anhydrous MoCI~with t-BuSLi in 1,2-dimethoxyethane (>45% yield). The molecular structure has been determined by a single-crystal X-ray analysis. The compound crystallizes in tetragonal space group p42212with a = 10.975 (1) A, c = 10.249 (1) A, and with two molecules in a unit cell. The structure, solved by the heavy-atom method, was refined to R = 0.065 for 578 reflections. The geometry of sulfur atoms around Mo(1V) has an approximately Du configuration with two distinct SMoS angles (average 116.9 and 95.6') and a single MoS distance (2.235 (3) A).
So far homoleptic tetracoordinate molybdenum(1V) compounds MOL, remain a rarity. Thermally stable M o ( N R ~ () R~ = Me, Et) and relatively unstable M o ( O R ) ~(R = t-Bu, t-BuCH,) derived
Complexes thus obtained assume higher coordination numbers than four5 and in general are rather inert. So that a new thiolato molybdenum family having no oxo ligands could be developed, therefrom are well-known2S3 and constitute rare examples of more labile sulfur complexes are apparently needed as starting monomeric, diamagnetic tetracoordinate d2 ions. Conspicuously, material. This paper describes the first successful preparation tetrakis(thiolato)molybdenum(IV) compounds have not been of a tetrakis(thio1ate) compound, M O ( ~ - B U S )and ~ , its molecular reported yet. Closely related may be M o ( S C H ~ C H ~ S C H ~ C H ~ S )structure ~ as determined by a single-crystal X-ray analysis. This which is, however, a hexacoordinate trigonal prismatic Mo(1V) compound indeed was found to be substitution active providing c o m p o ~ n d .W ~ e have been interested in obtaining Mo(SR), since accesses to a variety of molybdenum thiolate compounds. it would serve as a potential starting material for molybdenum Experimental Section sulfur compounds having no oxo ligands. In the molybdenumPhysical Measurements. All manipulations of air-sensitive molybdesulfur chemistry, chelating disulfur ligands such as dithioacid num complexes were carried out under a nitrogen atmosphere. IR and (dithiocarbamate and xanthate) or dithiolate are commonly weds5 UV-visible spectra were recorded on a Hitachi Model 295 and Hitachi EPS-3T spectrometer, respectively. IH NMR were recorded with a Jeol JNM-4H-100 or Jeol JNM-PMX-60. Cyclic voltammetric measure(1) (a) Osaka University. (b) Oska City University. (2) Chisholm, M. H.; Reichert, W. W.; Thornton, P. J. Am. Chem. SOC. ments were made with a Hokuto Denko Potentiostat Model HA-201 at 1978, ZOO, 2744 and references cited therein. 25 OC with use of DMF solutions containing 0.1 M tetraethylammonium (3) For reviews see: (a) Bradley, D. C.; Chisholm, M. H. Acc. Chem. Res. perchlorate as supporting electrolyte. 1976,9, 273. (b) Bradley, D. C. Adv. Inorg. Chem. Radiochem. 1972, 15, Materials. Anhydrous MoCI4 was prepared from MoCl, (Climax 259. (c) Bradley, D. C.; Fisher, K. J. Int. Rev. Sci.: Inorg. Chem., Ser. One, Molybdenum Co.) according to a literature method.6 tert-Butyl mer1972, 5, 65. captan (Nakarai Chemical Co., Ltd.) was distilled before use. tert-Butyl (4) Hyde, J.; Magin, L.; Zubieta, J. J. Chem. Soc., Chem. Commun. 1980, 204. ( 5 ) (a) Coucouvanis, D. Prog. Inorg. Chem. 1979,26,301. (b) Willemse, J.; Cras, J. A.; Steggerda, J. J.; Keijzers, C. P. S t r u t . Bonding 1976, 28, 83. (6) Kepert, D. L.; Mandyczewsky, R. Inorg. Chem. 1968, 7, 2091.
0002-7863/81/1503-3011$01.25/00 1981 American Chemical Society
Otsuka et al.
3012 J. Am. Chem. SOC.,Vol. 103, No. 11, 1981
Figure 1. Stereodiagram of one unit cell showing the packing of Mo(t-BuS),. The view is down the c axis with b axis vertical. isocyanide was prepared by the method described previ~usly.~All the solvents were dried with appropriate desiccants (sodium, calciumhydride or Pz05)and distilled under a nitrogen atmosphere. Preparation of Mo( &BUS),. To a THF (20 mL) solution of t-BUSH (10.8 g, 120 ”01) was added slowly at 0 OC a hexane solution (75 mL) of n-BuLi (1.6 M); the resultant solution was stirred for 30 min. THF was added to the solution to make the total volume 120 mL. This solution was used as a 1.0 M solution of t-BuSLi. A 1.62-g (6.81 mmol) sample of MoCl, was dissolved in 60 mL of 1,2-dimethoxyethane(DME) while the temperature was kept below 5 OC by an ice bath. To the solution cooled at 0 “C was added while stirring 30 mL of the above 1.0 M solution of t-BuSLi, and the stirring continued for 4 h. The dark reddish violet reaction mixture was evaporated to dryness under vacuum, and the residue was extracted with hexane several times. Complete removal of the solvent from the filtered extract gave a dark red solid material. Recrystallization of this material with the use of a small amount of hexane at 0 “C gave pure Mo(t-BUS), in +45% yield; red prism, mp 108 OC dec. It sublimes at 70 OC torr). Anal. Calcd for C L ~ H ~ ~ S ~C,M42.46; O : H, 8.02. Found: C, 42.11, H, 8.10. X-ray Crystallographic Procedure. A dark red tabular crystal (0.35 X 0.21 X 0.10 mm) grown from hexane was carefully sealed in a Lindemann capillary under a nitrogen atmosphere and used to obtain X-ray data which were recorded on a Philips PWl 100 four-circle diffractometer with use of graphite monochromatic Mo K a (0.7107 A) radiation and a a-28 scan technique. The observed systematic absences are hOO for h odd and 001 for I odd, consistent with space group p42212. The cell constants, determined by a least-squares fit of 18 28 values, were a = 10.975 (1) and c = 10.249 (1) A. The experimental and calculated (2 = 2) densities of, respectively, 1.18 and 1.217 g/cm3 indicated I / , molecule Mo(SC(CH,),),/asymmetric unit. All unique diffraction maximum with 20 < 55O were collected. Three reference reflections monitored every 180 min displayed neither systematic nor significant deviations from their initial intensities. Of the 872 reflections surveyed in this manner, 578 (66.3%) had Z > 3 4 ) and were classified as observed. The intensities were corrected for Lorentz and polarization factors, but an absorption correction was not made. The structure was solved by the usual heavy-atom procedure: deconvolutionof a Patterson function to reveal the Mo and the S positions and location of nonhydrogen atoms in a subsequent electron density synthesis. The structure was refined by full-matrix least-squares techniques, minimizing the function w(lFoI - IFC1)*;the weights were assigned as ~.O/C@,)~. R and R, were 0.099 and 0.1 10 after three cycles of isotropic least-squares refinement. Six cycles of refinement with anisotropic temperature factors for the Mo, S, and isotropic C atoms converged to R = 0.065 and R, = 0.088.’ Neutral atomic scattering factors of Cromer and Waber9 were (7) Otsuka, S.;Mori, K.; Yamagami, K. J. Org. Chem. 1966, 31, 4170. (8) Busing, W. R.; Martin, K. 0.; Levy, H. A. “ORFLS, A Fortran
Crystallographic Least Square Programme”; U. S. Atomic Energy Commission Report ORNL-TM-305; Oak Ridge National Laboratory, Oak Ridge, TN, 1970. Johnson, C. A. “ORTEP-11, A Fortran Thermal Ellipsoid Plot Programme for Crystal Structure Illustrations”;US.Atomic Energy Commission Report ORNL-3794 (2nd revision with supplemental instructions); Oak Ridge National Laboratory, Oak Ridge, TN, 1971. Sakurai, T., Ed. “UNICS, The Universal Crystallographic Computation Program System”; The CrystallographicSociety of Japan: Tokyo, Japan, 1967. (9) Cromer, D. T.; Waber, J. T. “International Tables for X-ray Crystallography”;Ibers, J. A., Hamilton, W. C., Eds.; Kynoch Press: Birmingham, England, 1974; Vol. IV, Table 2.2A, p 72.
Table I. UV-Visible Spectrum of Mo(t-BuS),‘ hmaX,nm
E , M - ‘ cm-’
238 282 320 sh 355 sh
25 000 23000 4300 3200
hmaX,nm e,M-’ cm-’ 7200 1100 1500
420 518 720
In hexane.
used for all atoms. They were all corrected for the real part of the anomalous dispersion. Fractional coordinates and thermal parameters are listed in Table 11. The important bond lengths and bond and dihedral angles are shown in Table 111. A table of structure factors is available as supplemental material.
Results and Discussion Preparation. MoC14 in 1,Zdimethoxyethane reacts readily with t-BuSLi at low temperature according to eq 1. The isolation of MoC14
+ 4t-BuSLi
-
Mo(t-BUS),
+ 4LiCl
(1)
Mo(t-BuS), can be achieved through hexane extraction with satisfactory yield (>45%). The preparative success depends greatly on the choice of solvent; e.g., the reaction in T H F gave a much poorer yield. Anhydrous and anaerobic conditions are necessary for the successful snythesis. An obvious alternative prepartion of this compound, substitution reaction of the known compound Mo(NMe2)2, was attempted. Thus the reaction with a slight excess of t-BUSH carried out in pentane (28 ‘C, 5 h) followed by usual workup was found to produce the compound in a low yield (
