3150
COMMUNICATIONS TO THE EDITOR
TABLE I
Vol. 81
hence be paramagnetic if the niobium were indeed tetravalent. Recently Rolsten3 reported the presumably isomorphous Ta14 to be diamagnetic. Borneol 0.17 1.47 Kolsten speculated that the unpaired electron must Isoborneol 0.14 2.41 be paired by the formation of a dimer, or else TaIl exo-cis-Bicycloj3.3.01octan1.41 3.83 may exist in the solid state as Ta+3Ta+'18. l y e 2-olh wish to report the preliminary results of the strucendo-cis-Bicyclo[3.3.0]octan0.36 4.02 tural determination of Nb14 by X-ray diffraction 2-01* and strong evidence of metal-metal interaction Epiandrosterone 4.58 0.53 which will readily explain its diamagnetism as well Androsterone 3.63 0.6G as that of TaI4. ris-cis-2-DecalolC 0.08 X.22 Single crystals of NbI4 were generously furnished cis-tuans-2-DecalolC 0.0' 10.62 to us by Corbett and Seabaugh. Since the comTertiary alcohols pound is extremely sensitive to water and oxygen Patchouli alcohol ( 1 ) d 3.46 0.i0 the crystals were isolated in glass capillaries which Epipatchouli alcohol ( 1 I ) d 0,045 4.52 were first evacuated and then hermetically sealed. Oxo-patchouli alcohol ( I I I ) d 1.55 0.51 Three dimensional X-ray data were taken with both Oxo-epipatchouli alcohol (1Y)d 0.2 0.15 n'eissenberg anti precession cameras utilizing Epimaaliole 0.48 2.74 V o K a radiation. The crystals are orthorhombic Maaliole 0 . OR 3.03 with $pace group CincSl and lattice coastants a = Secondary acetates hZ (RI-60) 7.67 X., b = 13.28 X., and c = 13.93 11. There are Borneol acetate 0.31 5.08 eight NbI4 species per unit cell. Isoborneol acetate 0.04 5.94 Patterson and Fourier projections of the three Epiandrosterone acetate 1.07 4.56 principal zones gave the essential features of the Androsterone acetate 0.29 5.98 structure. X least squares refinement of the ob70 of total ion yield. ectra taken with a CEC served reflections resulted in values of R = Z lF01 21-103C mass spectrometer; "inlet temp. 140". b'.A. C. - F,,'XI Fo' < 0.14 for each zone. Corn. & Brown I. a n d H. E. Petree. THIS TOURNAL. 80. 2852 ~ - ~ --., - ~ , The structure consists of infinite chains parallel (19'58). LV. G. Dauben and E. Hoerger, ibzd.,'73,' 1504 (1951). G. Biichi, R. E. Erickson and S.Wakabayashi, to the "a" axis formed by KbIs octahedra sharing t o be published. e G. Biichi, M. Schach v. Wittenau and two opposite edges. The niobium atoms are D. M. White, ibid., 81, 1968 (1959). shifted from the centersoof the octahedra of iodine atoms, which are 3.83 A. apart, toward each other in pairs such t h a t the $stance between the paired niobium atoms is 3.2 *I. The only reasonable explanation for this shift involves a metal-metal interaction in which the unpaired electrons are COUpled by exchange forming a weak metal-metal bond. I , Ri OH, RP = CHI, R3 = Hz It should be noted t h a t Nb14 was first reported to 11, Rz = CHI, Rz = OH, Ra Hz be paramagnetic; in view of our structural results 111, Ri = OH,Rz = CHI, R3 0 I%',Ri = CHI, Rz = OH, Ra 0 a redetermination of the magnetic moment by CorThus, if the molecular models of epimeric alco- bett and Seabaugh4 revealed NbI4 to be diamaghols show an appreciable' difference in their steric netic a t room temperature. This compound reprerequirements, the mass spectra should allow the as- sents the first known structure of its configuration which possesses metal-metal interactions. signment of their stereochemistry. -4 qualitative interpretation of the nature of We are indebted t o Professors G. Biichi, A. C. Cope and ITr. G. Dauben for generous gifts of sam- bonding about each niobium atom can be given in ples and to the National Science Foundation for terms of simple molecular orbital theory based on octahedral symmetry. The dZ2 and dx2-y2 metal financial support (Grant G 5051). orbitals plus the one 5s and three 5p metal orbitals (1) For example, eso- and eiido-norborneol gave inconclusive results. interact with the corresponding symmetry orbitals DEPARTMEST O F CHEMISTRY I;.BIEMAXN of the iodides to give bonding a-type molecular orMASSACHUSETTS ISSTITUTE OF TECHNOLOGY bitals. The unshared electron for each niobium CAMBRIDGE 39, MASSACHUSETTS J. SEIBL can be placed in the d,, orbital; the metal-metal RECEIVED APRIL1, 1959 bond for two paired niobiums is thus accomplished by the overlap of these two neighboring orbitals NIOBIUM TETRAIODIDE : ITS STRUCTURE AND which are directed toward each other (z.e., the x and NATURE OF BONDING' y axes are along the shared iodide directions). The Sir: unoccupied d,, and d,,, orbitals of each niobium no Since the preparation of NbI4 by Corbett and doubt are utilized in x-bonding with the filled tSeabaugh2 there has been some question as to type symmetry orbitals of the iodides. Since the diamagnetism of Ta14 can be explained whether the tetravalent oxidation state of niobium exists in the solid state. One normally would ex- easily by a similar structure, and especially since pect NbI4 t o possess one unpaired electron and X-ray data on T a I j 3 indicate its structure to be directly related to that of NbIbS(z.e., the lattice con(1) Presented in par t before the Di\-ision of Physical Chemistry, Abundance" of
Secondary alcohols
ion (M-18)
M
~
~
~
American Chemical Society Meeting, April 5-10, 1959. (2) J. Corbett and P. Seabaugh, .I. Inorg. X'uci. Ciiem., 6, 207 ( 1958).
(3) R R o l s t e n T H I Jor ~ R N A L 8 0 , 2932 (1058) (4) J Corbett and P Seabaugh, prlrate communication (3) I, Dah1 m d N Nelson to be published.
COMMUNICATIONS TO THE EDITOR
June 20, 1959
3151
material, e.g., 111,5could be detected in the rearrangement product 11. Similarly, the vinyl ether of 4-cholesten-3,B-01 was obtained in 54% yield; m.p. 56-57', [ff]"D +11' (CHC13) (Found: 84.G1; H, 11.90). This on rearrangement in decalin a t 185-200° for 4 hr. gave directly an 83% yield of A3-5,B-cholestenylacetaldehyde, m.p. 66-69', [ff]*'D +8So (CHC13) (Found: C, 84.55; H, 11.71). Catalytic reduction converted the latter to 3p-cholestanylacetaldehyde (m.p. 58-61', [ ( Y ] ? ~ D+42' (CHCl,); found: c, 84.10; H , 12.16), which was further transformed (via ethylene thioacetal formation and desulfurization with Raney nickel) into 5P-ethylcholestane, ~ (CHC13) (Found: C, m.p. 67-69', [ a l Z 5+18' 87.17; H, 12.87). In model experiments, the vinyl ethers of Azcyclohexenol and 3-methyl-A2-cyclohexenol were DEPARTMENT OF CHEMISTRY USIVERSITYOF WISCOSSIN LAWRENCE F. DAHL found to give the corresponding cyclohexenylMADISON 6, WISCONSIS DALEL WAMPLER acetaldehydes in 95 and 93% .yields, respectively. Oxidation of these products with silver oxide, and RECEIVED APRIL 0, 1959 iodolactonizationG of the resulting unsaturated acids, demonstrated the assigned structures. STEREOSPECIFIC INTRODUCTION OF ANGULAR Further extensions of this work are in progress. SUBSTITUENTS BY T H E CLAISEN REARRANGEMENT The award of a Frederick Gardner Cottrell Grant Sir: from Research Corporation supporting the initial By virtue of its intramolecular character, the phases of this study and a current grant from the Claisen rearrangement of vinyl allyl ethers ap- General Research Fund of the University of Kansas peared to us to offer the possibility of being a po- are gratefully acknowledged. tentially useful method for the stereospecific intro(5) W. Huckel and U. Wcirffel, Bey., 89, 2098 (1956). duction of an angular group into suitably consti(6) E. E. r a n Tamelen and M . Shamma, THIS J O U R N A L , 76, 2316 tuted fused polycyclic systems, e . g . (1964).
stants are a = 6.65 and 6.54: b = 13.93 and 14.01, and c = 20.10 and 40.36 A. for TaTh and NbTS, respectively), an attempt was made to index the powder lines given for TaI4 by Rolsten3 assuming isomorphism of the two compounds. Structure factors and "d" spacings were calculated for all the possible reflections, and we were able to correlate most of the "d" values listed for TaI4. We feel that the structures of the two compounds are similar a t least with regard to the local configuration about the metal atoms. We are indebted to the Numerical Analysis Laboratory of the University of LVisconsin for the use of their IBM 650 computer. We also wish to acknowledge the use of the facilities of the Ames Laboratory of the U. S. Atomic Energy Commission.
c,
DEPARTMENT OF CHEMISTRY ALBERTW. BURGSTAHLER IVAX C. KORDXN RECEIVED APRIL 27, 1959
UNIVERSITY OF KAXSAS LAWRENCE, KANSAS U
I
,
CH7CHO I1
I11
T H E NATURE OF T H E SIDE
CHAIN I N FUMAGILLIN' Although elimination is reported to be a strongly competing side reaction in the related rearrange- Sir: ment of phenyl ethers of substituted allyl alcohols, Alcohol-I, CI6Hz6O4,~ b t a i n e d ~from - ~ the antiwe have found that, with highly purified vinyl ethers, biotic fumagillin by hydrolysis, is now shown t o the major course of the reaction is the desired contain the side chain I by chemical transformaformation of the corresponding allylacetaldehydes. tions and by n.m.r. spectral considerations. The vinyl ether I (b.p. 52-53' (0.08 mm.); CH? found: C, 80.88; H, 10.38) was prepared from A9~10-octalol-l by the transetherification procedure -C-CH2-CH2CH=C( CH3)2 of ll'atanabe and Conlon2 and purified by passage I through basic alumina with petroleum ether (yield Previous work has established the presence of the 41%). On being heated in a sealed tube a t 195' for 2 hr. it furnished an 8070 yield of A4(10)-9-octa- isopropylidene group, and isocaproic acid has been lylacetaldehyde (11), b.p. 60-61' (0.08 mm.), as- isolated after oxidation of various transformation sayed by the 2,4-dinitrophenylhydrazone, m.p. products of a l ~ o h o l - I . ~ Tetrahydroalcohol-I ,~ ab,4 118-121' (Found: C, 60.88; H, 6.43; N, 15.63). in which the double bond and epoxide have been Hydrogenation of I1 on palladium-charcoal, and r e d ~ c e d ,formed ~ a crystalline monoacetate,* CISthen oxidation of the resulting saturated aldehyde, (1) Aided by a grant from the f\-ational Institutes of Health, afforded the known3 cis-9-decalylacetic acid, m.p. ( 2 ) J. R. Schenck, hZ. P. Hargie, D. S. Tarbell and P. Hoffman, 7 6 , 2274 (1953). 114-115', which was further identified by degrada- THISJOURNAL, (3) J. R. Schenck. M. P. Hargie and A. Isarasena, zbid., 7 7 , 5606 tion3 to cis-9-decalincarboxylic acid, m.p. 121122°.3n4 Only minor amounts of dienic elimination (1955). (4) D. S. Tarbell, P. Hoffman, H. R. Al-Kazimi, G. A. Page, J. (1) See D. S. Tarbell in R . Adams, "Organic Reactions," Vol. 11, John Wiley and Sons, Inc., New York, X. Y.,1944, pp. 14-15. (2) E '. H. Watanabe and L. E. Conlon, THIS JOURNAL, 79, 2828 (1957). (3) R . D Haworth and A. F. Turner, J . Chem. SOC.,1240 (1958). (4) W. G. Dauben and J. B. Rogan, THIS JOURNAL, 79, 5002 (1957). We are deeply grateful to Professor Dauhen for a comparison sample of this acid.
M. Ross, H R . Vogt and B. Wargotz, ibid.. 7 7 , 5610 (1955). (5) J. K. Landquist, J . Chem. SOL.,4237 (1956). (6) D. D. Chapman and D. S. Tarbell, THISJOURNAL, 8 0 , 3679 (1958). (7) J. M. Ross, D. S.Tarbell, W. E. Lovett and A. D. Cross, ibid., 78, 4675 (1956). (8) Microanalyses and infrared absorption on new compounds were in agreement with the empirical formulas and structures.
