April 20, 1964
COMMUNICATIONS TO THE EDITOR
1643
in acetonitrile a t the reflux temperature for 16 hr. and 12 positions of the carborane icosahedron are not The infrared spectrum of C-ethinylcarborane con involved in the degradation reaction. The evidence outlined above suggests t h a t B ~ C Z H ~ ? -tained sharp C-H stretchingbands a t 3.08 and 3.32 p and a carbon-carbon triple bond stretching band a t 4.70 p . and B 9C2H13 are icosahedral fragments isoelectronic The 3.08 1.1 C-H band is attributed to the acetylenic C-H. with the hypothetical B1,H12-3 and the known3 BllH13-* ions. The removal of a boron atom from the Treatment of biscarborane with 2 equiv. of butyl4 , 5, 7, or 11 positions2 or from the 3 or 6 positions2 is lithium in diethyl ether solution followed by 2 equiv. indicated by the kinetic results and hydrogen analysis of methyl iodide afforded C,C’-dimethylbiscarborane, data. The fact t h a t position isomers are not observed m.p. 193-194’. Arzal. Calcd. for B20CsH26: with C-monosubstituted carboranes suggests t h a t t h e B, 68.77; C , 22.90; H, 8.33. Found: B, 6745; boron atom in position 3 or 6 is removed. This would C, 22.81; H , 8.83. This alkylation reaction unplace the two carbon atoms as near neighbors in the doubtedly involves the dianion of biscarborane since pentagonal face of the assumed icosahedral fragment. similar treatment of carborane produces a nucleophilic dianion. Acknowledgment.-The authors are indebted to Mr. R . Donald Strahm for the analytical data and Mrs. When the biscarborane dianion was treated with Carolyn Haney for n.m.r. spectra. This work was sup2 molecular equivalents of iodine, C,C’-diiodobisported by Contract No. DA-01-021 ORD-5135 with the carborane was obtained in low yield, m.p. 183-184’. U. S. Army Ordnance Corps. Anal. Calcd. for BZoC4H2oI~:B, 40.19; C, 8 92; H , 3.74; I, 47.14. Found: B, 39.70; C , 9.13; H , (3) V . D. Aftandilian, H . C. Miller, G W. Parshall, and E. L. Muetterties, I n o r g Chem , 1, 734 (1562). 3.96; I, 46.36. ( 4 ) Alfred P . Sloan Foundation Fellow. These results constitute the first report of a species ( 5 ) Department of Chemistry, T h e University of California, Riverside, Calif. which is composed of two singly linked icosahedra. THEJOSIAHGORGAS LABORATORY ROBERT A. WIESBOECK The B24H22-2ion, isoelectronic with biscarborane but ROHMAND HAASCO. M . FREDERICK HAWTH0RNE4t6 linked through boron atoms, has not been reported .\LABAMA HUSTSVILLE, although a B20H18-4 probably composed of two singly RECEIVED FEBRUARY 17, 1964 linked Blopolyhedra has been d e ~ c r i b e d . ~ The preparation and reactions of biscarborane( 12) are summarized below. The Preparation of 1- [ 1,2-Dicarbaclovododecaboranyl(12)1BIOH~~(CH~CX)Z HCEC-C=CH HCECC-CH 1,2-dicarbaclovododecaborane(12) CHCS
Sir
\O/ B ; ~ H ~ ~
IC---C-C-CI The recent reports of the preparation of icosahedral \o/ \o/ 1,2-dicarbaclovododecaborane(12) and its derivatives1r2 prompt us to report the preparation of 1-[1,2-dicarbaclovododecaboranyl( 12) 1- 1,2 -dicarbaclovododecaborane( 12)3 and its precursor, l-ethinyl-lj2-dicarba2 BuLi clovododecaborane( 12). +-H CC- CCH LiCC-C--CLi Treatment of an acetonitrile solution of BloH12\o/ \o/ \o/ \o/ (CH3CN)2 with diacetylene4 a t the reflux temperature BioHlo BioHlo B~oHlo BioHla for a period of 5 hr. produced C-ethinylcarborane, 2CHd 359;’$ m.p. 75-78’ (Anal. Calcd. for B10C4H12: B, 64.27; C, 28.54; H, 7.20. Found: B, 62.22; C, CHaC-C-C-CCHs 28.70, H , 7 . 7 0 ) , and biscarborane(l2), 4%, m.p. 309\o/ \o/ 310’ ( A n d . Calcd. for BzoC4Hz2: B, 74.45; C, 16.53; BioHio BioHia H , 9.02. Found: B, 75.30; C, 17.50; H , 8.20). Acknowledgment.-The authors are indebted to M r . Improved yields (ca. 607,) of biscarborane were obR. Donald Strahm for the analytical data. This retained from C-ethinylcarborane and BloH12(CHaCN)2 search was supported by Contract No. DA-01-021 (1) C C Clark, U S Patent 3,062,756 (Nov. 6 , 1562); T I, Heying, J. ORD-5135 with the U. S. Army Ordnance Corps. W Ager-. J r . . S I.. Clark, D J Mangold, H 1.. Goldstein, M Hillman, R J. Polak, and J \V. Szymanski, I i r o y g . Cheni., 2 , 1085 (1963), H. Schroeder, T . I, Heying, and J R Reiner, ibid., 2 , 1092 (1963); T L. Heying, J . W. Ager, J r , S 1, Clark, R P Alexander. S Papetti, J. A. Reid, and S. I. Trotz, ibid , 2 , 1097 (19G3); S. Papetti and T I,. Heying, ibid.,2 , 1105 (1563); R P Alexander and H Schi-oedei-, ibid, 2 , 1107 (1963); hT hI Fein, J . Bobinski. S Mayes, S Schwartz, and 11 S. Cohen. i b i d , 2 , 1111 (1563); M hl Fein, D Grafstein, J E . Paustian, J Bobinski, B 11.Lichstein. S. Mayes, S S Schwartz, and 11 S. Cohen, r b i d . , 2 , 1115 (1963); D Grafstein, J Bobinski, J Dvorak, H Smith, N. Schwartz, 51. S Cohen, and 11. hl Fein, ibrd , 2 , 1120 (1463); D . Grafstein, J . Bobinski, J . Dvorak, J E Paustian, H F. Smith, S Karlan. C . Vogel, and hl hI. Fein, ibid., 2, 1125 (1563). n. Grafstein and J . Dvorak, ibrd , 2, 1128 (1963). (2) T h e nomenclature employed here was recently adopted by the S o m e n clature Committee of the Inorganic Division of the American Chemical Society See R Adams, I x o r g Chrm., 2 , 1087 (1963). (3) Hereafter referred t o a s biscarborane and symbolically described by
HC-C-C-
\o/
BioHio
\o/
CH
BioHio
( 4 ) J . B Armitage, E R. H . Jones, and M . C Whiting, J . Chem. Soc., 44 (1951)
( 5 ) hf. F. Hawthorne, R . L. Pilling, P . F. Stokely, and P 21. G a r r e t t . J . A m Chem. S O C . , 86, 3704 (1563). ( 6 ) Department of Chemistry, T h e University of California, Riverside, Calif. (7) Alfred P . Sloan Research Fellow.
JOHKA. DCPOST T H E JOSIAH GORGAS LABORATORY M. FREDERICK HAIVTHORKE6,’ ROHMA N D HAASCOMPANY ALABAMA HUXTSVILLE, RECEIVED FEBRUARY li, 1964
Continuity of Bond Force Constants between Normal Molecules and Lennard- Jones Pairs
Sir: There are a number of striking empirical correlations between bond lengths, force constants, and bond dissociation energies. One of the earliest and most widely
COMMUNICATIONS TO THE EDITOR
1644
Vol. 86
-
-
-
quoted is Badger’s rule’ for stretching force constants
F
=
1.86 X 105/(Re- d , j ) 3 dynes cm.-’
(1)
where Re is the equilibrium bond length in A . and dtj is a function of the position of bonded atoms in the periodic table. Herschbach and Laurie? showed that an even simpler relation gave a better over-all correlation (excepting only diatomic alkali metal molecules)
Re = ail - bll log F (2) where alj and bij depend only on the rows of the periodic table of the two atoms being bonded, with the transition elements being regarded as a separate row. The continuity of bonding between ordinary molecules and the loose, Lennard-Jones, noble gas, twoatom pair is given by extending eq. 2 to noble gas clusters. The Lennard-Jones potential-energy function is 1.’
=
+)12
-
(31
(3)
Values of e and u are tabulated by Hirschfelder, Curtiss, and Bird.3 The minimum in this function is found where dV,/dR = 0, and i t is
Re = 2‘”u (4) The force constant in Badger’s rule is defined as the second derivative of the potential-energy function, evaluated a t the minimum F = (d2V dR2), = 7 2 ~ / 2 ‘ / ‘ c ~ ~ ( 5 ) In terms of e k and u as tabulated in ref. 3, p. 1110, the Lennard-Jones stretching force constant is
F=
79 O6(e k)
dynes cm.- 1
(6)
U2
For homonuclear clusters, He-He, Ne-Ne, etc., the (1) R M Badger, J Chem P h y s . , 9 , 128 (1933); 3. 710 (1934) ( 2 ) D R Herschbach and 1‘.W. Laurie, i b i d . , 36, 458 (1961), Lawrence Radiation Laboratory Report 9694 (1961). ( 3 ) J 0 Hirschfelder. C. F. Curtiss, and B R . Bii-d, “hIolecular Theory of Gases and Liquids,” John Wiley and Sons, Inc., New York. N. Y . , 1954.
“bond length” is found from eq. 3 , and the “force constant” from eq. 6. For heteronuclear clusters, He-Ne, Ne-Ar, etc., the usual combination rules are used €11 = ( € i * ~ l l ) l ’ z
2ui,
=
(Uti
(7)
+ “u)
The points for stable Hz and all excited electronic states4 of Hs are entered as A in Fig. 1, and the He-He cluster is similarly entered. One straight line labeled H-H connects all these points, in agreement with eq. 2 . All uncharged (that is, omitting H F + , etc.) diatomic molecules between H and members of the first row (Li through F ) in ref. 2 are entered as all bonds between H and these elements in polyatomic molecules as tabulated by Cottrel15 are also entered, and the He-Ne cluster is so entered. With the exception of one excited electronic state of LiH labeled b, all these points lie very close to the straight line, H-1, in Fig. 1. A11 stable and excited, uncharged, diatomic,? and polyatomic5 molecules between members of the first row of the periodic table (excluding Li2,however) and the cluster Ne-Ne are entered as 0 in Fig. 1. Except for the point labeled a , an excited electronic state of ?J\J~, all these points lie very close to the line 1-1. This extraordinary correlation includes the following : CO, Nz, CIC, C=C, C-C, C=N, C--l\;,C-F,NO,O=O, BN, 0-0, FF, C-F, LiF, BeO, NeNe; Fig. 1 shows some sense of continuity of bonding between these extreme cases. With the exception of Naz all molecules between members of the second row of the periodic table as given by ref. 2 and 3 are entered as V in Fig. 1 ; some examples are SaC1, AlCl, Si?, Pz, SiS. MgC1, C12, and ArAr. With the exception of KZ,points in the third row of the periodic table are related to KrKr with the symbol @ in Fig. 1. n‘ith the exception of CSZ,the members of the fourth row including XeXe are plotted
+,
( 4 ) G . Herzberg. “Spectra of Diatomic Molecules,’’ 1) van Nostrand Co , Inc., S e w York, N . Y , 1950, pp 530-.532 ( 5 ) T . L. Cottrell, “ T h e Strength of Chemical Bonds,” 2nd E d . , B u t t e r worths Scientific Publications. London, 19.58
COMMUNICATIONS TO THE EDITOR
April 20, 1964
TABLE I ai, A N D b i , FROM EQ.2 INCLUDING KOBLEGAS PARAMETERS CLUSTERS BUT OMITTING HOMONUCLEAR ALKALIMETAL MOLECULES H
1
2
3
4
3T
4T
a,,
H 1 2 3 4
1.18
1.46 1.85
1 74 2 06 2 36
H 1 2 3 4
0.58
0.56 0.55
0 64 0 63 0 70
1 2 2 2
82 15 45 57
1 96 2 28 2 62 2 71 2 87
1.71 2.12
1.81 2 22
b,, 0 0 0 0
66 64 73 74
0 0 0 0 0
0.71 0.72
0.78 0.73
72 70 79 81 87
as X in Fig. 1. In each case the noble gas cluster and the ordinary molecules lie close to a single straight line. Similarly, all molecules from ref. 2 and 5 were plotted, such as H-2, 1-2, 2--3, 3-4, etc. The parameters Q and bfj of eq. 2 for all cases are given in Table I. It can be seen that these terms vary slowly and smoothly over the periodic table. The constant btj is closely related to Pauling's constant 0.6, which defines bond order in terms of bond length.6 When b,, is 0.6 (it almost always is close to this value) then the force constant is directly proportional to Pauling's bond order. On very tenuous grounds, a similar correlation between dissociation energy and bond length was recently p r o p o ~ e d . ~The present correlation between force constants and bond lengths is much more heavily documented and much more nearly convincing. This striking evidence for continuity of bonding for all types of bonds may be taken as support for the previous6 postulate, which interpolated bond energies between that for noble gas pairs and that for ordinary singlebonded molecules.8 (6) L . Pauling, J. A m . Chem. Soc., 69, 542 (1947). (7) H . S . Johnston and C . P a r r , ibid., 85, 2544 (1963). ( 8 ) This research was supported b y N S F G r a n t G-20976.
DEPARTMENT O F CHEMISTRY HAROLD S . JOHNSTON UNIVERSITY OF CALIFORNIA BERKELEY 4, CALIFORNIA RECEIVED JANUARY 24, 1964
Electron Transfer Equilibria. 111. Disproportionation of Monoalkali Adducts of Stilbene'
Sir : The previously reported behavior of the monoalkali adducts of stilbene suggests that they show little tendency to disproportionate (eq. 1). - 4 We have found that by proper choice of solvent and metal ion the range of K can be made to vary from < l o p 3 to > lo3. K
2(RH-, M + j J r RH
+ RH-*, 2 M +
(11
As in the case of the alkali metal adducts of tetraphenylethylene, the disproportionation constant is a 'r5
(1) (a) P a r t I: J. F. Garst and R . S. Cole, J. A m . Chem. SOC.,84, 4352 (19621, (b) p a r t 11: J. F. Garst, E. R . Zabolotny, and R. S. Cole, i b i d . . in press (2) D . E . Paul, D. Lipkin, and S . I. Weissman, ibid., 7 8 , 116 (1956) (3) K . Morigaki, K . K u w a t a , and K . Hirota, Buii. Chem. Soc. J a p a n , 33, 958 (1960). (4) J . W . B. Reesor, J. G. S m i t h , and G. F. Wright, J . Org. Chem., 18, 940 (1954).
1645
TABLE I DISPROPORTIONATION CONSTANTS OF MONOALKALI STILBENES Metal
Diethyl ether
Dioxane
2-MeTHF
THF
Li >io3 NR" >io3
