Inorganic Chemistry, Vol. 17, No. 12, 1978 3695
Notes
Notes Contribution from the Department of Chemistry, University of Arizona, Tucson, Arizona 85721
Table I. Crystallographic Details for [Mo, 0, S(SCH,CH,O)(dedtc), ]
yellow rectangular parallelepiped dimensions, 0.10 X 0.10 X mm 0.52 cryst system monoclinic space group P2, In 0 , .& 7.258 (2) James T. Huneke, Katsumoto Yamanouchi, b , .& 20.414 (4) and John H. Enemark* c, a 15.134 (5) P, deg 94.41 (2) Received March 20, I978 a3 2235 (1) temp,'C 24.0 z 4 Triply bridged binuclear oxomolybdenum(V) complexes molwt 628.60 w e r e first recognized during investigations of t h e reactions of p(obsd); 1.843 (6)O di-y-oxo-bis(oxomolybdenum(V)) c o m p o u n d s ( M O ~ O ~ ~ ' g cmp(calcd); 1.867 complexes) with thiols.'J Another triply bridged species was g cmt h e unexpected result of a recrystallization f r o m c h l ~ r o f o r m . ~ cryst faces {loo}, ( 0 2 1 ~ X-ray structure d e t e r m i n a t i o n s of t h e products of these ( O U , (021), fortuitous syntheses of triply bridged oxomolybdenum(V) (012) dimers have established the stereochemistries of three different radiation Mo Ka (A 0.710 69 A)b bridging s y ~ t e m s ~ which - ~ are shown schematically in 1-3.
Triply Bridged Molybdenum(V) Dimers. Crystal and Molecular Structure of y-( 2-Mercaptoethanolato-S,0)-y-sulfidobis[oxo( N,N-diethyldithiocarbamato)molybdenum(V)], M02~2S(SCH,CH20)(SzCN(C2H5)2)2
color habit
v,
Ph
20 range, deg
4-50 scan technique e(cryst)20 (counter) scan rate, 2.00 29.30' deg/min scan range, [2@(Ka1)- 0.81 + deg [20(Koc,) + 0.81 scan:bkgd 1: 1 time standards 3 every 9 1 reflection& no. of inde3957 pendent data no. of data 2888 with Fo2> 3dFO2) no. of varia226 bles refined final Re 0.030 final RWe 0.037 abs coeff, cm-' 16.5f std dev of an 1.18 observn of unit wt --f
a Density was averaged over four trials by neutral bouyancy in aqueous zinc bromide. Graphite crystal monochromator. Variable with more time spent on weaker reflections. The maximum decrease in intensity was 1.4%, and no decay correction IF, I;& = [ c w ( lFolwas required. e R = 2 IIF, I - lFcll/~ lFcI)*/2wF,z]1'2. An empirical absorption correction was applied (see text)
Ph
'
.
-
orientation matrix were based on a least-squares fit of the setting angles 18'. Peak widths at half-height of of 20 reflections with 20 = 5 less than 0.25' for w scans of several reflections indicated a satisfactory 1 mosiac spread for the crystal. Axial photographs revealed C2, ( 2 / m ) Laue symmetry, indicating that the crystal belonged to the monoclinic S y s t e m l3has two equivalent SPh bridges and a bridging C1 crystal class. Automated data collection was carried out under the atom trans to the terminal 0 atoms of each Mo atom; has control of a NOVA 1200 computer using the Syntex P21Fortran IV a bridging 0 atom cis to the terminal 0 atoms of e a c h Mo diffractometer system;g details are presented in Table I. atom and two distinctly different SPh bridges; 32 is similar Examination of the complete set of intensity data revealed the to 2 b u t has a bridging OR m o i e t y trans to the terminal 0 systematic absences h01 for h I = 2n + 1 and OkO for k = 2n atom of each Mo atom. 1, consistent with the nonstandard centrosymmetric space group P2,/n. Systematic extension of the c h e m i s t r y of triply bridged Data were corrected for absorption by an empirical method using a M o ( V ) complexes has recently become possible by t h e delocal modification of the computer program TAPER.^ Thirteen strong reflections, distributed over the range of 20 values used in data velopment of synthetic routes to other triply bridged system^.^ collection and having 274 < x < 296O, were measured in 10' inOf particular interest to us are complexes with a bridging crements around the diffraction vector, $, from $ = 0' to $ = 350'. sulfido group. Herein w e report the structure of Mo202The maximum empirical absorption correction factor was 1.23. S(SCH2CH20)(S2CN(C2H5),),(4), the sulfido a n a l o g u e of Solution and Refmement of Structure. Details concerning computer bridging s y s t e m 3, and t a b u l a t e a n d compare t h e metrical programs used can be found in a previous r e p ~ r t .Scattering ~ factor details of all four triply bridged systems. tables for neutral nonhydrogen atoms" and spherically bonded hydrogen'la were generated from the coefficients of analytical apExperimental Section proximations; the real and imaginary parts of the anomalous dispersion The yellow compound MO~O~S(SCH&H~O)(S~CN(C,H,)~)~ (4)5 correction were included only for Mo and S.llb The structure was was kindly supplied by Dr. W. E. Newton, and crystals were grown solved by direct methods which revealed the coordinates of two Mo from dichloromethane by slow evaporation in air at ambient temand four S atoms. All the remaining nonhydrogen atoms were located peratures. The IR spectra of the yellow powder and the recrystallized by subsequent structure factor calculations and difference electron material in KBr pellets are identical as obtained on a Perkin-Elmer density maps. Hydrogen atom positions were calculated and included Model 735 spectrophotometer. A very strong band at 940 cm-' is as fixed contributions in the final refinement using isotropic thermal found for the v(M-0). A medium-intensity band observed at 460 parameters of 6.0 A2; the final R factors are given in Table I. cm-' can be assigned6*'to the molybdenum-bridging sulfur stretching Refinement was based on F, with Cw(lFol - IFc1)2being minimized. frequency. The weights were taken as w = 4F,2/u2(F2) and a value of 0.04 was Crystal Structure Determination. A crystal of the title compound assigned t o p in the expression for u ( P ) . " Only data having F: t which showed sharp extinction at 90' intervals under polarized light 30(F2) were used in refinement. A structure factor calculation for was selected for X-ray crystallography. The needle axis of the crystal all 3957 data gave R = 0.057 and R , = 0.046. The final electron ( a ) was nearly coincident with the C$ axis of a Syntex P2, four-circle difference map had a maximum residual of 0.52 e/A', about 1.0 A diffractometer. The measurement of unit cell parameters and the from a Mo atom. The final positional parameters for all the refined
I Ph
2
3
z4
+
0020-1669/78/1317-3695$01 .OO/O
0 1978 American Chemical Society
+
Notes
3696 Inorganic Chenzistry, Vol, 17, No. 12, I978 Table IIa. Final Atomic Parameters f o r [Mo,O,S~SCH,CH,O)(dedtc), 1" Atom
I10 2
s1
. ? 2 99( 2 )
53
03 .' 0-M-X and Y-M-Z >
W. E. Newton, J. L Corbin, and J. W. McDonald, Abstracts, 167th National Meeting of the American Chemical Society,Los Angeles, Calif., April 1974, No. INOR 35. J. I. Gelder, J. H. Enemark, G. Wolterman, D. A. Boston, and G. P. Haight, J . Am. Chem. SOC.,97, 1616 (1975). G. Bunzey, J. H. Enemark, J. I. Gelder, K. Yamanouchi, and W. E. Newton, J . Less-Common Met., 54, 101 (1977). K. Yamanouchi, J. H. Enemark, J. W. McDonald, and W. E. Newton, J . Am. Chem. SOC.,99, 3529 (1977). W. E. Newton, G.J.-J. Chen, and J. W. McDonald, J. Am. Chem. SOC., 98, 5387 (1976). V. R. Ott, D. S. Swieter, and F. A. Schultz,Inorg. Chem., 16, 2538 (1977). W. E. Newton and J. W. McDonald, J . Less-Common Met., 54, 51 (~1 977) - , I .~
,
“Syntex P2, Fortran Operations Manual”, Syntex Analytical Instruments, Cupertino, Calif., 1975. J. H. Enemark, R. D. Feltham, J. Riker-Nappier, and K. F. Bizot, Inorg. Chem., 14, 624 (1975). D. T. Cromer and J. B. Mann, Acta Crystallogr., Sect. A, 24, 321 (1 968). “International Tables for X-ray Crystallography”,Vol. IV, Kynoch Press, Birmingham, England, 1974: (a) pp 99-101; (b) pp 149-150. P. W. R. Corfield, R. J. Doedens, and J. A. Ibers, Inorg. Chem., 6 , 197 (1967). G. Bunzey, J. H. Enemark, J. K. Howie, and D. T. Sawyer, J . Am. Chem. SOC.,99, 4168 (1977). E. I. Stiefel, Prog. Inorg. Chem., 22, 1 (1977). B. Spivack and Z. Dori, Coord. Chem. Rev.,17, 19 (1975). J. I. Gelder and J. H. Enemark, Inorg. Chem., 15, 1839 (1976). J. K. Howie and D. T. Sawyer, Inorg. Chem., 15, 1892 (1976). Recent synthetic approaches to the molybdenum site in nitrogenase have also resulted in triply bridged binuclear molybdenum species: T. E. Wolff, J. M. Berg, C. Warrick, K. 0. Hodgson, R. H. Holm, and R. B. Frankel, J . Am. Chem. SOC.,100, 4630 (1978); G. Christou, C. D. Garner, F. E. Mabbs, and T. J. King, submitted for publication (we thank C. D. Garner for a preprint).
