5112
J. Am. Chem. SOC.1981, 103, 5772-5778
A Highly Distorted Octahedral d4 Compound, c~s-Mo(~-BuS)~(~-BUNC)~ Masato Kamata,'* Ken Hirotsu,lb Taiichi Higuchi,IbKazuyuki Tatsumi,lc Roald Hoffmann,*lc Toshikatsu Yoshida,'. and Sei Otsuka*lP Contribution from the Departments of Chemistry, Faculty of Engineering Science, Osaka University, Toyonaka, Osaka 560, Japan, Osaka City University, Sumiyoshiku, Osaka 558, Japan, and Cornell University, Zthaca, New York, 14853. Received March 16, 1981, Revised Manuscript Received May 18, 1981
Abstract: The crystal structure of the coordinatively unsaturated d4 molybdenum complex cis-Mo(t-B~S)~(t-BuNC)~ has been determined by X-ray diffraction. The crystals are monoclinic: a = 18.616 (7) A, b = 11.823 (2) A, c = 18.667 (6) A, B = 116.00 (3)O, space group P 2 1 / c with four formula weights per unit cell. The structure was refined to R = 0.069 and R, = 0.086 for 4838 reflections. The six-coordinate molecule is substantially deformed from the ideal octahedral geometry, so that the S-Mo-S and C-Mo-C angles in the equatorial plane are 115.3 (1) and 73.7 (4)O. A molecular orbital analysis of traces the deformation to the d4 electron count. The lowest lying unoccupied MO consists of an a model, MO(HS)~(HNC),, S p S p bonding combination and a Mo d orbital. The resulting imbalance in S-S bonding leads to an opening up of the S-Mc-S angle. The cyclic voltammogram shows two quasireversible redox events between -1.0 and +1 .O V, a one-electron reduction at Ell* = -0.17 V, and an oxidation at Ellz = +0.45 V. 'Hand 13CNMR, UV-visible, and IR spectra are also reported.
While many six-coordinate d4 metal complexes assume octahedral or near octahedral molecular structures,2 significantly deformed octahedra have been found for Mo(I1) compounds of the MXzLzL'2 (X = monobasic anion such as Br-, CHY, RO-; L, L' = neutral ligands such as pyridine, CO, PR3) or M(SzCNR2)2L2 (L = CO) type.3 We also know from the literature& that the Mo(I1) ion seeks seven-coordination in its mononuclear complexes, thus achieving the inert-gas configuration. Examples may be found in Mo(RNC)*+ and many mixed complexes containing CO and other ligands. Thus six-coordinate Mo(I1) compounds are considered to be coordinatively unsaturated. We have been interested in obtaining coordinatively unsaturated low-valent molybdenum compounds, possibly capable of binding biologically interesting substrates such as acetylene, CO, diazenes, or dinitrogen. Despite intensive current interest in (thiolato) metal complexes, the organosulfur ligands involved in low-valent molybdenum complexes so far have been rather limited. A vast chemistry of dithioacid and 1,l-dithiolate compounds containing Mo(1V) has developed,' but only a few monomeric Mo(I1) or Mo(II1) compounds are known, e.g., the above-mentioned carbonyldithiocarbamate Mo(I1) compounds.3b This situation may be due to the strong propensity of Mo(I1) or Mo(II1) ion to form dimeric or polymeric compounds. Mononuclear, low-valent molybdenum compounds of monodentate thiolate are, to our best knowledge, completely absent in the literatures, apart from M ~ ( S R ) ~ ( d p p (dppe e ) ~ = Ph2PCH2CHzPPh2).* Recently we (1) (a) Department of Chemistry, Faculty of Engineering Science, Osaka University, Toyonaka, Osaka 560, Japan. (b) Department of Chemistry, Osaka City University, Sumiyoshiku, Osaka 558, Japan. (c) Department of Chemistry, Cornell University, Ithaca, NY, 14853. (2) (a) Glavan, K. A.; Whittle, R.; Johnson, J. F.; Elder, R. C.; Deutsch, E. J. Am. Chem. SOC.1980,102,2103-2104. (b) Bandoli, G.; Clemente, D. A.; Mazzi, U. J. Chem. SOC.,Dalton Trans. 1976, 125-130; Ibid. 1977, 1837-1844. (c) Trop, H. S.; Davison, A.; Jones,A. G.; Davis, M. A.; Szalda, D. J.; Lippard, J. J. Inorg. Chem. 1980, 19, 1105-1117. (3) (a) Chisholm, M. H.; Huffman, J. C.; Kelly, R. L. J. Am. Chem. Soc. 1979, 101, 7615-7617. (b) Templeton, J. L.; Ward, B. D. Ibid. 1980, 102, 6568-6569. (c) Drew, M. G. B.; Tomkins, I. B.; Colton, R. Aust. J . Chem. 1970, 23, 2517-2520. (4) Stiefel, E. I. Prog. Inorg. Chem. 1977, 22, 1-223. (5) (a) Lewis, D. F.; Lippard, S. J. Inorg. Chem. 1972,11, 621-626. (b) Lewis, D. F.;Lippard, S. J. J . Am. Chem. SOC.1975, 97, 2697-2702. (6) (a) Wood, T. E.; Deaton, J. C.; Corning, J.; Wild, R. E.; Walton, R. A. Inorg. Chem. 1980,19,2614-2619 and references cited therein. (b) Chatt, J.; Pombeiro, A. J. L.; Richard, R. L. J . Chem. SOC.,Dalton Tram. 1979, 1585-1590. (c) Brindon, B. J.; Edwards, D. A.; Paddick, K. E.; Drew, M. G. B. Ibid. 1980, 1317-1323. (d) Girolami, G. S.; Andersen, R. A. J . Organomet. Chem. 1979,182, C43-C45. (7) Coucouvanis, D. Prog. Inorg. Chem. 1979, 26, 302-469.
were able to prepare a novel six-coordinate Mo(I1) compound, Mo(t-BuS)z(t-BuNC)p (1) from M o ( ~ - B u S )The ~ . ~deep ~ emR N C
R = 1-Bu
c
N R
1 erald green compound 1 is diamagnetic. A general theoretical analysis of six-coordinate d4 complexes'0 led us to anticipate a deformation in such a compound. A single-crystal X-ray diffraction study, described in this paper, indeed revealed a considerably deformed octahedron. The structural chemistry of the complex and a theoretical exploration of its deformation are the subject of this work. Compound 1 was found to be very substitution active and extremely versatile. The reaction chemistry, however, will be described elsewhere.
Experimental Section Physical Measurements. Spectroscopic and electrochemical measurements were made by instruments described in the previous paper," in a pure nitrogen atmosphere. The I3CN M R spectra were recorded on a JEOL 4H 100- or 360-MHz Bruker WM-360 wb instrument. X-ray CrystallographicProcedure. A deep emerald green crystal (0.58 X 0.25 X 0.15 mm), grown from toluene-containinghexane (1:0.2vol ratio), was carefully sealed in a Lindermann capillary under a nitrogen atmosphere and used for data collection. Crystal data: CaH5,N4S2Mo, M,= 606.84, monoclinic, space group P21/c. On the basis of 48 reflections, the following unit cell parameters were obtained: a = 18.616 (7) A,b = 11.823 (2) A,c = 18.667 (6) A, @ = 116.00 (3)O, V(for Z = 4) = 3693 (2) A3, dald = 1.09 pcm-), and p(Mo K a ) = 4.8 cm-'. Data were collected on an automated Philips PWllOO four-circle diffractometer with graphite-monochromated Mo K a radiation (0.7107 A). The diffracted intensities were measured by the -28 technique with a take-off angle of 4.5O. The scan rate was 2O/min for 28. Background counts were taken at both ends of the scan range. A total of 4838 (8) Chatt, J.; Lloyd, J. P.; Richard, R. L. J. Chem. SOC.,Dalton Tram. 1976, 565-568. (9) (a) Kamata, M.; Yoshida, T.;Otsuka, S.; Hirotsu, K.; Higuchi, T. J . Am. Chem. SOC.1981, 103, 3572-4. (b) Otsuka, S.; Kamata, M.; Hirotsu, K.;Higuchi, T. Ibid. 1981, 103, 301 1-4. (10) KublEek, P.; Hoffmann, R. J . Am. Chem. SOC.1981, 103, 4320.
0002-7863/81/1503-5772$01.25/00 1981 American Chemical Society
The d4 Compound cis-Mo(t-BuSJ2(t-BuNC),
J. Am. Chem. SOC., Vol. 103, No. 19, 1981 5113
Table I. Fractional Coordinates and Temperature Factors for Mo(t-BuS),(f-BuNC)P atom
X
Y
2
W11)
U(22)
W33)
Mo S(1) S(2) N(1) N(2) N(3) N(4) C(1) C(2) C(3) C(4) C(5) C(6) C(7) C(8) C(9) C(10) C(11) C(12) C(13) C(14) C(15) C(16) C(17) (318) C(19) C(20) C(21) C(25)
0.26700 (4) 0.2437 (2) 0.2691 (1) 0.0944 (5) 0.4446 (4) 0.3085 (6) 0.3293 (6) 0.1547 (5) 0.3810 (5) 0.2931 (6) 0.3072 (6) 0.1410 (6) 0.0816 (6) 0.1479 (8) 0.1190 (7) 0.1801 (5) 0.1987 (6) 0.1045 (6) 0.1685 (7) 0.0275 (6) -0.0041 (9) -0.0400 (8) 0.0483 (10) 0.5149 (6) 0.5815 (7) 0.4969 (8) 0.5387 (9) 0.3167 (9) 0.3383 (10)
0.6508 (1) 0.8221 (2) 0.4851 (2) 0.6249 (6) 0.7117 (7) 0.8123 (7) 0.4875 (7) 0.6338 (7) 0.6822 (7) 0.7555 (8) 0.5439 (8) 0.8956 (8) 0.7957 (10) 0.9860 (10) 0.9251 (10) 0.3930 (8) 0.3001 (9) 0.4615 (9) 0.3358 (9) 0.6112 (10) 0.4925 (11) 0.6950 (14) 0.6581 (17) 0.7834 (10) 0.7080 (14) 0.8761 (11) 0.8293 (14) 0.8822 (10) 0.4183 (11)
0.21588 (4) 0.1427 (2) 0.1452 (1) 0.2147 (5) 0.2378 (5) 0.3703 (5) 0.3709 (5) 0.2109 (5) 0.2287 (5) 0.3149 (5) 0.3155 (5) 0.0971 (6) 0.0416 (7) 0.0475 (8) 0.1632 (7) 0.1039 (5) 0.0537 (7) 0.0494 (6) 0.1734 (7) 0.2335 (6) 0.2136 (10) 0.1738 (10) 0.3121 (8) 0.2585 (6) 0.2568 (10) 0.1990(8) 0.3428 (8) 0.4370 (6) 0.4362 (7)
Y
0.0361 (4) 0.049 (2) 0.046 (1) 0.052 (5) 0.080 (6) 0.056 (6) 0.056 (6) 0.036 (5) 0.044 (6) 0.048 (6) 0.046 (6) 0.049 (7) 0.090 (9) 0.068 (8) 0.076 (9) 0.045 (6) 0.057 (7) 0.061 (7) 0.073 (8) 0.098 (9) 0.087 (10) 0.153 (15) 0.289 (24) 0.091 (8) 0.156 (15) 0.105 (11) 0.213 (19) 0.086 (10) 0.075 (9) atom
0.0397 (4) 0.071 (2) 0.059 (2) 0.088 (6) 0.068 (6) 0.062 (6) 0.059 (6) 0.062 (6) 0.046 (5) 0.055 (6) 0.048 (6) 0.087 (8) 0.107 (10) 0.139 (12) 0.126 (10) 0.065 (7) 0.091 (8) 0.081 (8) 0.106 (9) 0.094 (8) 0.217 (17) 0.195 (17) 0.092 (10) 0.058 (6) 0.212 (17) 0.127 (11) 0.100 (10) 0.040 (7) 0.082 (9)
X
0.0425 (4) 0.063 (2) 0.045 (1) 0.066 (5) 0.047 (5) 0.123 (8) 0.145 (9) 0.055 (6) 0.048 (5) 0.077 (7) 0.082 (7) 0.071 (7) 0.057 (7) 0.119 (11) 0.114 (10) 0.050 (6) 0.082 (8) 0.046 (6) 0.093 (8) 0.058 (6) 0.131 (12) 0.073 (10) 0.148 (14) 0.049 (6) 0.069 (9) 0.118 (11) 0.134 (13) 0.202 (15) 0.284 (19) U,8’
atom
C(22) 0.2427 (15) C(23) 0.3087 (15) C(24) 0.3997 (16) Standard deviations of
Z
0.8423 (20) 0.9993 (22) 0.8583 (21)
0.4591 (15) 0.244 (11) 0.4064 (15) 0.251 (11) 0.5186 (16) 0.258 (12) the least significant figures are given in pare
reflections were obtained for a 28 range of 2.&46.0°, of which 3355 have I > 344 and were considered as observed. Three reference reflections monitored every 180 min displayed neither systematic nor significant deviations from their initial intensities. The intensities were corrected for Lorentz and polarization factors, but no absorption correction was applied. The structure was solved by MULTAN.’~ From the E map, molybdenum and two sulfur atoms were located. The remaining non-hydrogen atoms were located in succeeding difference Fourier syntheses. The structure was refined by least-squares techniques, minimizing the function zw(lFol - lFc1)2;the weights were assigned as ~.O/CT(F,,)~. R and R, were 0.098 and 0.1 15 after three cycles of isotropic refinement. In the following refinement, anisotropic temperature factors were assigned to the Mo, S, N, and 22 of the 28 carbon atoms. Isotropic temperature factors were assigned to the other six carbon atoms, since previous least-squares calculation indicated very large thermal motion of these atoms. Final least-squares refinement converged to R = 0.069 and R, = 0.086.12 Neutral atomic scattering factors of Cromer and Waberl) were 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 I . The bond lengths and bond angles are shown in Tables I1 and 111, respectively. The equatorial plane 1 is defined as the least-squares plane containing two S atoms and two carbon atoms, C(3) and C(4). Selected dihedral angles are shown in Table IV. The important intermolecular distances are listed in Table V. A table of structure factors is available as supplementary material to this paper.
Results and Discussion Physical Properties. The title compound, 1, which can be obtained selectively from reaction of M O ( ~ - B U Swith ) ~ an excess (11) Germain, G.; Main, P.; Woolfson, M. M. Acra Crystallogr., Sect. B 1970,836,274-285. Woolfson, M. M. Acta Crystallogr.,Sect. A 1977, A33, 219-225. (12) Sakurai, T., Ed. “Unics, The Universal Crystallographic Computation Program System”, The Crystallographic Society of Japan, 1967. Johnson, C. K. “ORTEP”, Oak Ridge National Laboratory Report ORNL-TM-3794. (13) 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.
C(26) C(27) C(28)
-0.045 (4) 0.001 (1) 0.000 (1) -0.004 (4) -0.010 (5) -0.005 (5) 0.009 (6) -0.007 (4) -0.002 (4) -0.001 (5) -0.002 (5) 0.017 (5) 0.006 (6) 0.022 (8) 0.027 (8) -0.003 (5) -0.001 (6) 0.010 (5) -0.014 (7) -0.023 (6) -0.036 (9) 0.025 (10) -0.037 (15) -0.028 (6) -0.004 (9) -0.018 (9) -0.100 (13) 0.037 (9) 0.068 (11)
0.0222 (3) 0.038 (1) 0.024 (1) 0.050 (5) 0.021 (4) 0.052 (6) 0.049 (6) 0.037 (5) 0.019 (4) 0.037 (6) 0.032 (5) 0.036 (6) 0.023 (7) 0.066 (9) 0.086 (9) 0.020 (5) 0.036 (7) -0.002 (5) 0.062 (7) 0.055 (6) 0.122 (13) 0.042 (10) 0.085 (10) 0.014 (5) 0.077 (11) 0.040 (9) 0.063 (10) 0.028 (8) 0.113 (11)
X
Y
Z
-0.0008 (4) 0.015 (1) -0.010 (1) 0.002 (5) 0.005 (5) -0.011 (4) 0.015 (5) 0.002 (5) -0.001 (4) -0.002 (5) -0.000 ( 5 ) 0.021 (6) 0.012 (8) 0.060 (8) -0.003 (8) -0.016 (5) -0.031 (6) -0.018 (6) 0.007 (7) -0.023 (7) -0.018 (11) 0.004 (13) -0.046 (13) 0.007 (6) -0.002 (13) 0.065 (9) -0.067 (11) -0.014 (6) 0.038 (8) u, A2
0.3904 (10) 0.3588 (12) 0.2535 (21)
0.4713 (15) 0.3018 (17) 0.4170 (26)
0.5143 (10) 0.4245 (12) 0.4376 (20)
0.157 (6) 0.185 (8) 0.333 (16)
2.374 (3) 2.372 (3) 2.061 (10) 2.062 (10) 2.097 (10) 2.097 (9) 1.875 (10) 1.846 (9) 1.160 (14) 1.444 (16) 1.174 (13) 1.462 (13) 1.159 (13) 1.446 (15) 1.143 (12) 1.417 (17) 1.557 (14)
C(5)-C(7) CW-C(8) C( 9)-C( 10) C(9)-C(11) CW-C(l2) C(13)-C(14) C( 13)-C(15) C(13)-C(16) C( 17)-C(18) C( 17)-C( 19) C( 17)-C(20) C(2 1)-C(22) C(21)-C(23) C(2 1)C(24) C(25)C(26) C(25)-C(27) C(25)-C(28)
1.545 (18) 1.532 (20) 1.578 (16) 1.555 (12) 1.559 (18) 1.504 (17) 1.604 (17) 1.453 (20) 1.538 (20) 1.490 (18) 1.535 (18) 1.669 (37) 1.480 (28) 1.650 (25) 1.490 (19) 1.471 (25) 1.590 (47)
a Standard deviations of the least significant figure of each distance are given in parentheses.
of t-BuNC? is thermally fairly stable. After the toluene solution was heated at 100 O C for 10 h, it can be recovered without substantial loss. In the solid state it is moderately stable to air but in solution it reacts immediately with dioxygen. Compound 1 is soluble in most organic solvents, even slightly soluble in saturated hydrocarbons. It readily forms a well-developed single crystal suitable for X-ray crystallography. The electronic spectrum of 1 in hexane (Table VI) is characterized by a very intense charge-transfer band at 33 700 cm-l and several other strong absorptions in visible region. The IR C N stretching vibrations of the Nujol-mulled sample appear at 2120, 2080 (sh), and 1997 cm-’ and those of the hexane solution at 2120 (sh) and 2010 cm-I. These values may be compared with those of MO(~-BUNC):+~~~ and Mo(MeNC):+,14 which fall in the range of 2140-2160 cm-l. The lower frequencies of 1, showing the electron-donating effect of the thiolate ligands, are reasonable.
5774 J . Am. Chem. SOC.,Vol. 103, No. 19. 1981 Table III. Bond Angles (Deg) in Mo(t-BuS),(t-BuNC),a S(l)-Mo-S(2) S(l)-MO-C(l) S(l)-Mo-C(2) S(l)-M04(3) S(l)-Mo-C(4) S(2)-Mo-C(1) S(2)-Mo-C(2) S(2)-Mo-C(3) S(2)-MoC(4) C(l)-M04(2) C(l)-Mo-C(3) C(l)-M04(4) C(2)-Mo-C(3) C(2)-Mo-C(4) C(3)-Mo-C(4) Mo-S(l)-C(S) Mo-S(2)-C(9) C(l)-N(l)-C(l3) C(2)-N(2)-C(17) C(3)-N(3)-C(21) C(4)-N(4)-C(25) MO-C(l)-N(l) Mo-C(2)-N(2) Mo-C(3)-N(3) Mo-C(4)-N(4) S(l)-C(5)-C(6) S(l)-C(5)-C(7) S(l)-C(5)-C(8) C(6)-C(5)-C(7) C(6)-C(5)-C(8) C(7)-C(5)-C(8) S(2)-C(9jC(lO) S(2)-C(9)-C(ll) S(2)-C(9)-C(12)
115.3 (1) 97.5 (2) 80.4 (2) 85.3 (3) 158.2 (2) 99.1 (2) 86.9 (3) 157.5 (2) 84.8 (3) 174.0 (3) 86.3 (4) 86.7 (4) 87.8 (4) 93.2 (4) 73.7 (4) 119.7 (4) 119.2 (4) 170.5 (9) 160.2 (10) 172.4 (13) 166.9 (14) 174.4 (8) 172.8 (8) 179.0 (8) 178.6 (8) 108.3 (7) 104.1 (8) 109.6 (7) 110.3 (9) 112.5 (10) 111.8 (9) 105.5 (7) 110.8 (6) 109.6 (6)
C(lO)-C(9)-C(ll) C(10)4(9)C(12) C(ll)-C(9)-C(12) N(l)-C(l3)-C(14) N(l)-C(l3)-C(15) N(l)C(13)-C(16) C(14)-C(13)-C(15) C(14)-C(13)
