Inorgunic Chemistry, Vol. 9,N o . 9,1970
2188
these complexes incorporate only the linear pentamine since identical results were obtained with pentamine purified ain the hydrochloride8 as with distilled pentamine fraction. Moreover, amine isolated by acidic decomposition of the complexes was shown by gas chromatography to comprise only one component and its rttention time was identical with that of the major peak from hydrochloride-purified amine. In their work on complexes of the type [ (tetren)CoCl][X-I2, House and Garner were able to distinguish between geometrical isomers, mainly on the basis of differences in NH2 bending and NH stretching frequencies3 The major infrared bands for the iron complexes are listed in Table I, but these data cannot be correlated TABLE I INFRARED SPECTRA OF 'rETRAErHYLEXEPENTAMINE-IROS DERIVATIVES= Compd
3 4
5 6
7 Sujol mulls.
---
Assignment and freq, cm-1---
NHz str
co
3310 ni 3140 s 3270 s 3150 s 3150 vsb 3200 gbxo
1940 vs
* Doublet.
NH, bend
1620 m 1600 IV 1960 vs 1600 m 1950 vs 1600 m 1580 s 1650 w 1590 m Also 3450 cm-' assigned to HrO.
with those of House and Garner so the question of geometry remains open.
NOTES
seemed obvious that the base directly removed BHs from the structural pattern
leaving (BH)3 to form the observed thermally stable resin containing the base.2 The same process seemed evident in the B6Hg-induced trimerization of (CH3),NBH2, wherein (CH&NBHz .B4& could be recognized as an ir~termediate.~However, no base as weak as (CH&S could attack B6Hy by first removing BH3, for the complex (CH&S. BH3 is extensively dissociated in the vapor phase,6 as B5H9 itself is not. Instead, then, it appears that (CHJ2S invades B5H9to displace BH3 and attach itself to the remaining B4He moiety, which then undergoes a condensation to resin. The driving force of the reaction would be the extreme Lewisacid strength of the B4H6 moiety, beginning t o take effect as the B-H-B bridges in BsHg are loosened by thermal vibration. Thus it now seems reasonable that stronger bases, which require similar temperatures for dismemberment of BjH9, also first seize B4H6 and displace BH3, although the order of events is less obvious because the displaced BHa is irreversibly captured by these strong bases.
Experimental Section I n the initial experiment, a mixture of BjHg with excess (CHI)& was heated a t 75-90', forming hydrogen, nonvolatile solids, and diborane, which appeared as the dissociable complex (CHs)aS.BHa on condensation a t 25a.6 However, the decomposition of some of the diborane prevented a quantitative interpretation. For a better experiment, we employed a vertical double-walled COYTRIBUTIOS FROM THE DEPARTMENT O F CHEMISTRY, reaction vessel, with a 5 X 18 cm outer tube electrically heated to VYIVERSITV OF SOCTHERN CALIFORNIA, temperatures as high as 25CIo, while the inner 2 . 5 X 12 cm coldLos XSGELES,CALIFORNIA90007 finger was cooled to -33" by refluxing liquid ammonia. A lower tubulature a t -23" collected BHa as the (CH8)2Scomplex while the B;HQ-(CH~)~S mixture refluxed from the -33' coldThe Action of Dimethyl Sulfide finger. Under these conditions it was possible to prove a quantitative process by the millimole stoichiometry accompanying on Pentaborane(9)' the equation
Acknowledgments.-The author wishes to thank Dr. G. W. Parshall for helpful discussions and Miss Eleanor G. Applegate for technical assistance.
BY INDUB. MISHRAAND AXTONB. BURG
Recehed February 16, 1970
+
3(CHa)zS BC" --+ 8.91 3.060 Hz (CHa)%S.BHa (l/'n)[(CHa)zSBrH2]zn -5.00 -1.793 1 , 2 9 7 1,267 l,267/n ~
New insight into the action of bases on pentaborane(9) comes from its vapor-phase reaction with dimethyl sulfide a t temperatures above 75", to form diborane (or a BH3 complex) and a resin containing (CH&S. Stronger aprotic bases such as trimethylamine were known to form 2 : 1 solid adducts with BbH9,2-4 but heating these with excess base (in a closed chamber) produced 2 units of the base-BHs complex per BbH9. It (1) It is a pleasure t o acknowledge the generous support of this research b y the Office of Naval Research. (2) A. B. Burg, J . A m e r . Chem. SOC., 79, PI29 (1957). (3) A. B. Bui-g, X V I I t h Internatiunal Congress uf P u r e and Applied Chemistry, Butterworths, London, 1960, p 57. (4) R.1. L. Denniston a n d S. G. Shore, Abstracts, 158th National Meeting of t h e American Chemical Society, New York, K . Y . ,Sept 1969, No. I N O I I 104.
3.81
+
+
-_
1.267
This process was conducted in a series of stages a t higher and higher outer wall temperatures. During 48 hr a t 100' t h e progress was only 27,; in 9 hr a t 135", 670; in 9 hr a t 185", 17Tc; and in 3 hr a t 250-260°, 25T0',. The effective reaction temperatures must have been much lower, on account of rapid convection between the inner and outer walls. The nonvolatile solid product included an amorphous resin but also a more definitely crystalline component, the X-ray powder pattern of which appeared as a series of peaks above a broad continuum. The relative displacements were 3.18 (s), 3.99 ( i n ) , 4.31 ( L V ) , 4.58 (w),5.16 ( w ) , and 5.75 (vw)? Also ( 5 ) A. B. Burg and J. S. Sandhu, J . Amel.. C h m . SOL., 89, 1626 (1867). (6) A. B. Burg and I
