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COMMUNICATIONS TO THE EDITOR
is in the boat conformation* and is slightly staggered to relieve the transannular strain due to the intraannular interactions of the hydrogen atoms on carbons 4, 5 , 7 and 8. The interatomic distances and the relevant bond angles are summarized in Fig. 1. The infrared spectra of the complexes were measured in potassium bromide. I n all cases the absorption bands characteristic of the cyclooctadiene double bonds a t 1660 cm.-l (C=C) and 710 cm.-] (=CH) were absent. New bands appearing a t 1612 cm.-' and i46 cm.-l were assigned to the complexed olefin. The spectrum of I a exhibited a pair of bands at 1230 cni.-' and 1192 cm.-' of equal intensity, complexes I b and ICexhibited a similar pair of bands a t 1238 cm.-' and 118s cm.-', the intensity of the former being approximately twice t h a t of the latter. X minor difference was also observed in a pair of bands t h a t occurred a t nil cm.-' and 966 cm.-' in Ta and a t 971 cm.-' and 95i cm.-' in Ib and IC. X-Ray powder diffraction data also show t h a t the structure of complex I a is different from complexes I b and IC. Hendra and Powell9 have suggested t h a t the cuprous chloride-COD-1,5-complex prepared from hydrochloric acid solution involves the chair conformer of the olefin rather than the bout. The infrared spectra of complexes Ia-c are virtually identical with t h a t reported by these authors. Since the crystal structure determination of IC has shown t h a t the complexed olefin exists in the bout Conformation, it would certainly appear t h a t complexes Ia-c all involve the boat conformation of the olefin. If this were not the case, then the various complexes should exhibit major differences in the 1000-500 cm.-' region where most of the absorption bands are due to the skeletal vibrations of the eightmembered ring. We believe t h a t the minor spectral differences observed between I a and Ib and ICmay be attributed to two structurally different complexes. Complexes I b and IC possess the determined dimeric structure; complex Ia is polymeric and consists of COD molecules in the bout conformation joined by exocyclic cuprous chloride bridging. The spectral differences may then reside in the non-symmetrical nature of Ib and TC as opposed to the more symmetrical structure of I a . A more complete structural analysis of this complex will be reported elsewhere. 18) COL)-l,.j has been found t o exist in the boat configuration in its rhodium chloride complex: J . A. Ibers and K . G . Snyder, A c l n C v y s l . , 16, 9?,'3 (14ii2). ( Q ) P. J . Hendra and 11. n. Powell, Spurlrochim. Acln, 17, 918 (1961).
CEsTRAL BASICRESEARCH LABORATORY J . H. V A N D E S HESDE Esso RESEARCH ASD ENGINEERING Co. LISDES, SEK JERSEY WILLIAMC . BAIRD,J R . RECEIVED JAXUARY 11, 1963 EVIDENCE FOR THE EXISTENCE OF AN ORGANODITIN DIHYDRIDE l
Sir: l y e wish to record what we believe to be the first preparation of an organoditin dihydride, specifically, 1,1,2,2-tetra-n-butyl-l,2-dihydroditin. 1,1,2,2-Tetra-n-butyl-1,2-di~hloroditin,~ prepared by with treating 1,1,2,2-tetra-n-butyl-1,2-diacetoxyditin hydrogen chloride in anhydrous ether, was reduced3 ( 1 ) We thank M and T Chemicals, I n c . , f o r support of a portion of this work. ( 2 ) A. J Gibbons. A. K . Sawyer and .4.Ross, J , Ovg. C h e m . , 26, 230-1 (1961). 1:i) T h i s reduction was attempted b y J. G. S o l t e s a n d G. J. M . van der Kerk, "Functionally Substituted Orpanotin Compounds," T i n Research Inctitute, Greenford, hliddlesex, England, 1958. I t was later shown by the f o l l o w i n g uorker.; t h a t the compound which they believed t o be 1,1,2,2tetra i 2 ~ b u t y l - 1 , 2 - d i c h l o r o d i t i n was in reality his-(di-n-butylchlorotin) c,xide. (a) ref, 2 ; (b) I j . 1,. Alleston and A , G. Davis, Chem. Ind. (London), W!3 (l!)iil), (c) 0 H. Johnson, J . 01.g. C h e n . . 26, 22fi2 ( l ' 2 i O ) .
1701.
85
by lithium aluminum hydride in anhydrous ether to give the colorless liquid, 1,1,2,2-tetra-n-butyl-l,2dihydroditin (767,) (found: Sn, 50.51; calcd. for C16H36Sn2HZ:Sn, 30.75),n z 5 D 1.5205. A large Sn-H absorption band was found a t 1795 cm.-l with a faint shoulder a t 1835 cm.-'. The reaction of this hydride with a 1007, excess of glacial acetic acid over that required by eq. 1 gave a quantitative yield of hydrogen Bukh-SnBu? + 2HOAc + BuzSn-SnBu:! -+ ZH? (1) t
H
i
H
i
XCO
;
Ohc
and 1,1,2,2-tetra-n-butyl-1,2-diacetoxyditin. That the product of this reaction is a ditin was shown by its quantitative reaction with bromine forming di-n butylaceto~ybromotin~ isolated in 7070 yield. In previous work i t has been shown that di-n-butyltin dihydride reacts with two moles of acetic acid to produce di-n-butyltin d i a ~ e t a t e . ~ It follows that di-n-butyltin dihydride is not present in appreciable amount in the reduction product, which, therefore, must be 1,1,2,2-
tetra-n-butyl-l,2-dihydroditin. This hydride is more reactive toward acid than is di-n-butyltin dihydride, and, on exposure to air, rapidly forms a white solid whose tin analysis corresponds to that for di-n-butyltin oxide. Formation of this ditin dihydride, or a polytin dihydride,s is indicated in other reactions of di-n-butyltin dihydride. (a) Di-n-butyltin dihydride reacts with acetone to form isopropyl alcohol and di-n-butyltin.fi Infrared spectra of the reaction product mixture taken a t intervals showed not only t h e disappearance of Sn-H absorption of di-n-butyltin dihydride a t 1833 cm.-' b u t also the simultaneous appearance of new Sn-H absorption a t about 1785 cm.-'. (b) Decomposition of di-n-butyltin dihydride a t 100° constitutes a method for the preparation of di-n-butyltin. (Foutld: C, 41.34; H, 7.78;Sn, 51.10. Calcd. BunSnH? --+ Bu&
+ Hr
(2)
for C8HI8Sn: C, 41.45; H , 7.79; Sn, 50.96.) Infrared spectra of the reaction product mixture taken during the decomposition showed a decrease in the intensity of the Sn-H absorption a t 1S35 cm.-' accompanied by the appearance and increase in intensity of a Sn-H band a t 1780 cm.-'; when the decomposition was somewhat more than iO70 complete, only the latter band remained. Decrease in intensity of this band required prolonged heating. (c) Treatment of di-n-butyltin with di-n-butyltin dihydride in a 1: 1 molar ratio results in new Sn-H absorption a t about 1780 cm.-'. It has been reported by Neumann and Konigj that, in the case of diphenyltin dihydride, substitution of one hydride hydrogen by tin results in a lowering of the frequency of Sn-H absorption to about 1790 cm.-'. (4) (a) A K. Sawyer a n d H . G. K u i \ ~ i l a ,J . A m . c ' h t ' m .SOL , 82, 3938 ( I S f j O ) , ( b ) A. K . Sawyer a n d H . G . Kuivila, J . Oig. Chrfn , 27, 610 (l
