Communications to the Editor
437 1
in part by National Institutes of Health Grant No. GM 23609. Supplementary Material Available: Structure factor table for ~~-2-(a-hydroxybenzyl)oxythiamin chloride hydrochloride trihy-
drate, anisotropic thermal parameters, and table of interring separations (6 pages). Ordering information is given on any current masthead page.
References and Notes (1) In partial fulfillment of requirements for the Ph.D. degree, University of Pittsburgh. (2) A. Schellenberger. Angew. Chem., lnt. Ed. fngl., 6, 1024 (1967). (3) M. Sax, P. Puisinelli. and J. Pletcher. J. Am. Chem. SOC., 96, 155 (1974). (4) J. Pletcher, M. Sax, G.Blank, and M. Wood, J. Am. Chem. Soc., 99, 1396 (1977). (5) W. Shin, J. Pletcher, M. Sax, and G.Blank, J. Am. Chem. Soc., 101, 2462 (1979). (6) A. Gallo, private communication. (7) The DOS software for diffractometer control, data collection, and data reduction were obtained with the FACS-I system from Picker Corp. Numerous software modifications and additions have been implemented locally. (8) This is equivalent to the criterion l I3u(1). The terms are the same as those defined previously (see ref 20). (9) Programs written or modified by R. Shiono are contained in various technical
reports from the Department of Crystallography, University of Pittsburgh. (IO) G. Germain. P. Main, and M. M. Woolfson, Acta Crystallogr., Sect. A, 27, 368 (1971). (11) D. T. Cromer and J. T. Waber, Acta Crystallogr.. 18, 104 (1965). (12) R. F. Stewart, E. R. Davidson, and W. T. Simpson, J. Chem. Phys.. 42,3175 119651 \ - - - I -
(13) "international Tables for X-ray crystallography", Vol. 111, Kynoch Press, Birmingham, England, 1968, p 214. (14) . , (a) . J. Pletcher and M. Sax, J. Am. Chem. SOC.,94,3998 (1972): (b) Science, 154, 1331 (1966). (15) M. J. S. Dewar and H. N. Schmeising, Tetrahedron, 11, 96 (1960); D. R. Lide, Jr., ibid., 17, 125 (1962). (16) J. Pletcher, M Sax, S. Sengupta, J. Chu, and C. S. Yoo, Acta Crystallogr., Sect. 6.28. 2928 (1972). (17) W. Shin', J. Pletcher, G. Blank, and M. Sax, J. Am. Chem. Soc., 99, 3491 (1977). (18) M. F. Richardson, K. Franklin, and D. M. Thompson, J. Am. Chem. SOC., 97, 3204 (1975). (19) J. Pletcher. M. Wood, G.Blank, W. Shin, andM. Sax,Acta Crystakgr., Sect. 8. 33. 3349 (1977). (20) J.'Pleicher, d. Blank, M. Wood, and M. Sax, Acta Crystallogr., in press. (21) (a) The torsion angle p~ = C(5')-C(3,5')-N(3)-C(2) and pP = N(3)C(3,5')-C(5')-C(4'). An S conformation is specified by the torsion angles ( p ~flOOO, p p f150'). For more complete details see footnote 13 in ref 4. (b) psU= S(I ) - C ( ~ ) - C ( ~ C U ) - and C ( ~psp ~ ) = C(5)-C(5a)-C(5fit
-o(~Y).
(22) The ORTEP program is by C. K. Johnson, Oak Ridge National Laboratory, Oak Ridge, Tenn.. ORNL-3794, 1965. (23) C. E. Bugg, J. M. Thomas, M. Sundaralingam, and S. T. Rao, 6iopolymers, 10, 175 (1971). (24) F. Jordan, J. Am. Chem. SOC.,98, 808 (1976).
Communications to the Editor Synthesis and Characterization of Bis(fulva1ene)divanadium and the Crystal Structure of Its Oxidation Product, Bis(fulvalene)bis(acetonitrile)divanadium(lIl)( V-V) Bis(hexafluoroph0sphate)-Acetonitrile (1/ 1) Sir:
Because of the current interest in the structure and reactivity of coordinatively unsaturated metallocenes' and the formally analogous metallofulvalene derivatives,2 we wish to report our initial synthetic, physical, and X-ray structural studies of the bis( fulva1ene)divanadium system. The neutral (CiOH8)2V? (1) was obtained by the reaction of VC12-2THF3 with I equiv of fulvalene dianionZdin refluxing T H F . The dark purple air-sensitive product was isolated and purified by repeated sublimation under high vacuum a t 230 "C.4 The solubility of 1 in polar and nonpolar solvents is very low. The mass spectrum5 and infrared spectrum of 1 are similar to those for the neutral bis(fulvalene)dimetal derivatives of Ni,6J C O , Fe,6C ~ ~ and Cr.6bMagnetic susceptibility measurements on solid samples indicate that 1 is diamagnetic from 4.2 to 100 K. This is consistent with the observed diamagnetism of both the dicationic and neutral derivatives of all bis(fu1va1ene)dimetal complexes studied to date, from vanadium, with 286b and 30 valence electrons, respectively, to nickel, with 38 and 40h* valence electrons. The complete magnetic coupling found in 1, compared to the "parent" vanadocene with an open-shell 15-clectron structure and three unpaired electrons, can be rationalized by either a direct metal-metal interaction (bond) or by ligand-propagated exchange. Although X-ray crystallographic data for neutral ( C I O H ~ ) ~clearly N ~ Zindicate the presence of a ligand-propagated exchange,' an assessment of the relative contributions from each exchange mechanism for electron-deficient early transition metal derivatives must await similar detailed structural information. The oxidation of 1 with either 1 or 2 equiv of ferrocenium hexafluorophosphate per dinuclear vanadium complex in dry oxygen-free acetonitrile yields only a two-electron product, [($:v5-C~oH8)2(CH3CN)2V~( I II)( V- u 2 + ][ PF6-]2*CH3C N (2), that was isolated as brown microcrystals by the slow 0002-7863/79/1501-437 1$01.OO/O
addition of toluene.8 Magnetic susceptibility measurements in acetonitrile a t 3 10 K by the Evans N M R method9 indicate that 2 is paramagnetic with perf = 2.9 BM per dinuclear vanadium complex. Measurements on solid samples from 4 to 80 K indicate a pef( = 3.0 BM. These results establish the presence of two unpaired electrons for the dinuclear metal complex. The infrared spectrum of 2 exhibits terminal nitrile stretches a t 2320 and 2290 crn-l. Hygroscopic and air-sensitive single crystals of the acetonitrile solvate 2, obtained by recrystallization from acetonitrile/benzene, are orthorhombic and noncentrosymmetric, space group Cmc21 (C2(1 2 , No. 36), with CI = 7.771 (1) A, b = 20.556 (3) A, c = 18.324 (3) A, and Z = 4 ([(CloH8)rV2(NCCH3)2] [ P F ~ ~ ~ S C Hformula ~ C N units). The various statistical indicators calculated with normalized structure factors, as well as all stages of the structure solution and refinement, were in agreement with the choice of a noncentrosymmetric space group. Diffracted intensities were measured for 2193 independent reflections having 2 8 ~ ~
