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COMMUNICATIONS ro THE EDITOR
Vol. 80
tro enantiomer decayed to zero degrees with a half-
and analyzed for hydrogen and deuterium by the life of one hour a t 23", which is the same half-life quantitative pyrolytic decomposition of this mateobserved for the levo isomer. The lower specific rial to boron and hydrogen-deuterium a t 900" folrotation of the dextro isomer is due to the presence lowed by mass spectrometric measurements of the of some levo isomer in a relatively large quantity of H / D ratio. dextro isomer. Table I sets forth the infrared absorptions and Resolution of the complex cation D,L- [Si(acacja]+ deuterium analyses of several samples of decabointo its optical enantiomers indicates that the sili- rane which were equilibrated with deuterium oxide con(Ilr) is six-coordinate in this complex, and that in dioxane solution for varying periods of time a t the cation is octahedral. The possibility of seven- room temperature. coordination (coordination by the chloride ion) is As seen in Table I the first detectable deuterium remote in view of the conductivity of the complex which enters the decaborane molecule enters the in anhydrous chloroform solution. Additional de- bridge positions but longer equilibration times protails of the resolution of this and other six-coordi- duce appreciable exchange a t terminal positions. nate silicon(1V) complexes will appear in a forth- Furthermore the equilibration of a sample of BIOcoming publication. H10D4 (bridge-&) in pure dioxane produces after The authors wish to express their sincere appre- one day a t room temperature appreciable amounts ciation to the Union Carbide Corporation for a re- of absorption a t 5.25 p as a sharp band charactersearch fellowship grant which contributed signifi- istic of terminal B-D bonds. Similar rearrangecantly to the progress of this investigation. ment of deuterium in B l ~ H l ~ D (bridge-&) I decaboDEPARTMENT O F CHEMISTRY S. K. DHAR rane does not occur in methylene chloride solution VERA DORON under identical conditions of time and temperature. WAYNESTATEUSIVERSITY STANLEY KIRSCHNER DETROIT2, MICHIGAN Table I1 presents the results of three exchange RECEIVED DECEMBER 19, 1957 experiments carried out with decaborane and deuterium chloride in sealed bulbs a t room temperaDEUTERIUM EXCHANGE OF DECABORANE WITH ture. It is to be noted that methylene chloride DEUTERIUM OXIDE AND DEUTERIUM CHLORIDE solvent does not produce exchange. Sir: These results clearly point to the fact that the We wish to report the results of a series of deu- four bridge hydrogens of decaborane are rapidly terium exchange experiments which illustrate the removed by bases (water, dioxane, etc.) and are exchange of as many as eight hydrogen atoms of decaborane by deuterium and which further illus- easily replaced by acids (hydronium ion, hydrogen trate either the existence of two types of exchange- chloride, etc.). Furthermore, less rapid but apable hydrogens (bridge or terminal) or the dioxane preciable exchange involving terminal positions apcatalyzed migration of bridge deuterium to ter- pears to occur only in the presence of basic solvents such as dioxane or diethyl ether by what may be a minal positions. TABLE I RESULTS O F DYO-BIOH~~ EXCHANGE EXPERIMENTS I N DIOXAKE SOLUTION AT ROOMTEMPERATURE Equilibration time, hr.
-Initial BioH14
0.15 0.15 2.00 36.0 72.0
0.0S3 0.167 0.167 0.083 0.120
concn., mole/l.-Dz0
B-D infrared absorption
Bridge Bridge Bridge Bridge Bridge
3.10 6.20 6.20 3.10 1.55
+ extremely weak terminal + very weak terminal + weak terminal + moderate terminal + strong termirial
Deiiteriuni/ mole
2.3 4 ti 5 2
0 7 7.5
TABLE I1 EXCHANGE OF BlaH,4WITH DC1 Solvent
Dioxane Dioxane hlethyleiie chloride
Exchange time, hr.
114
96 93
--Initial DCI
0.036 .032 .0384
quantities, moles-BioHii
0.0024 ,0016 .004
Perdeuterodecaborane was prepared by the pyrolysis (100") of perdeuterodiborane. This material gave B-D stretching absorptions in the infrared a t 5.25 p (terminal-dlo) and 7.30 (bridged?). The latter absorption is characterized by a broad band and weak intensity. LVith normal decaborane the corresponding absorptions are found a t 3.5 and 5.25 p , respectively. All spectra were determined in carbon disulfide solution. Partially deuterated samples of decaborane (prepared as described below) were sublimed, weighed
B-D infrared absorption
Bridge $- strong terminal Bridge strong terminal Identical with B:oHI~
+
Deuterium! molt
6.2 5.9 0
base-catalyzed internal rearrangement of bridge deuterium to terminal positions or a base-catalyzed process involving another type of BlaH13- anion formed by direct removal of a terminal proton. That this latter terminal hydrogen exchange process is not as rapid as bridge exchange is apparent from the above results. REDSTOSEARSESAL RESEARCH HAWTHORNE DIV. OF ROHMAND HAASCo. M. FREDERICK ALABAMA Jor-is J. MILLER HUNTSVILLE, RECEIVED JANUARY 2 , 1958
