Boron-Nitrogen Bonds in the Higher Boranes

32 Boron-Nitrogen Bonds in the Higher Boranes WILLIAM N. LIPSCOMB and RUTH LEWIN

Downloaded by UNIV OF CALIFORNIA SAN DIEGO on August 17, 2015 | http://pubs.acs.org Publication Date: January 1, 1964 | doi: 10.1021/ba-1964-0042.ch032

Department of Chemistry, Harvard University, Cambridge 38, Mass.

The EtNH B H NHEt molecular structure, in which both a ligand Ν and a bridge Ν occur, is a particularly stable system. The relation of this structure to the problem concerning the boron radius is presented briefly. 2

8

11

A lthough a number of observations of mass spectra of boronhydride mixtures suggest the presence of a B hydride, no stable hydride of this type has yet been well characterized. It is therefore remark able that the nitrogen-bridged (NHEt) and ligand-substituted (NI^Et) derivative EtNH^ BgH NHEt (41) is so stable. Here, we examine the question of primary amines which in their reactions may more gener ally yield stable derivatives of the higher boranes. In addition, the high precision of the bond distances in this compound forms a basis for r e examination of the elusive covalent radius" (if any) of boron, and the boron-boron distances in the B framework lead to some understanding of the instabilities of the group of boron hydrides. 8

n

M

8

EtNH B H NHEt 2

Q

11

The molecular structure has been established by x-ray diffraction methods (41). A total of 1566 independent diffraction maxima from a

312

In Boron-Nitrogen Chemistry; Niedenzu, K.; Advances in Chemistry; American Chemical Society: Washington, DC, 1964.

32

LIPSCOMB AND LEW IΝ

Boron-Nitrogen

Bonds

313

crystal having four molecules in a unit cell {a = 24.35, δ = 5.98, c = 9.00 Α., and β = 94 5Γ) has been refined to a value of R = Z\]F \-\F I β

Q

c

\/z\F \ = 0.134. Only the Η atoms of one C H group, probably under going hindered rotation, could not be located with certainty. 3

0

The greater stability of this compound, as compared with that of the B hydride fraction, suggests that stable boron frameworks maybe made from higher boranes and their derivatives by using primary amines, such as ethy lamine, in the degradation reaction. It is possible that amines of the type H N R a r e unique in some of these dégradâtive reactions, because the resulting bridge NHet group has only N-H in the polyhedral surface (which contains eight B s, the bridge N, two terminal H's on B, one H on the bridge N, and two bridge H atoms). For this reason, the bridge Ν looks sterically like a BH group to the rest of the polyhedron, and the open face is neatly filled by Η atoms at approx imately vander Waals contacts. Thus it is unlikely that HNI^ is a suitable reagent for these degradation reactions, and, of course, NR3 cannot form a bridged Ν arrangement without loss of R. Loss of B H in the preparation (19) of EtNH Bg H NHEt from BgH^L and H2 NEt from B H L and 1^ NEt is consistent with symmetrical cleavage, and hence NH is probably not suitable. [Graybill, Pitochelli, and Haw thorne (19) thought that the reaction yielded B H NH Et" ion when NH Et was used as reagent, but made the remarkable statement that "other amines were strangely ineffective."] It is therefore suggested that primary amines may occupy a nearly unique place in the prepa ration of bridge Ν derivatives of the higher boranes. Two functions are probably served by the ligand group (here L = EtNH ) which is bonded to the boron framework by a single B - N bond. The first is a general stabilization produced by the partial transfer of negative charge to the boron framework, thus adding some flexibility in values of the over-all charges. Probably more important, however, is the second effect of charge transfer into the boron framework — in order tb facilitate Η atom rearrangement to the situation which best adjusts to the local charge requirements. 8


2

T

2

S

2

8

n

1 3

3

9

12

2

2

2

The Boron

Radius

This new compound provides some of the most precisely deter mined B - N distances, which here have standard deviations of about 0.007 A. The bridged Ν has two B - N bonds which are 1.573 and 1.574 A. in length, while the ligand B - N distance is 1.581 A. in length. These rather unexpectedly long B - N distances are in agree ment with B - N distances such as 1.58 A. in H N B H (51), 1.57 and 1.60 A. in NH BH NHE C 1 ' (50), 1.57 A. in cubic BN (63) and 1.59 A. in BH NME ) (43). If we take 1.58 A. as representative of the B-N single bond, and 1.47 A. as the N-N single bond distance, and make an electronegativity correction of -0.08|#Β-#ΝΙ» the boron radius is 0.925 A . , a surprisingly large value. A similarly large value of 0.895 A. occurs when one applies the Η radius of 0.37 A. and a small (0.01 A.) electronegativity correction to the BH distance (15) of 1.255 A. in B H " ion. The values are comparable to, but even larger than the single bond radius of 0.88 A. assigned by Pauling. 3

3

2

2

3

2

3

7

+

3

4


A D V A N C E S I N C H E M I S T R Y SERIES

314

On the other hand, one can find systematic evidence of boron radii as low as 0.80 or 0.81 A. (23), which is the single bond metallic r a dius assigned by Pauling. The icosahedral B H " ion has an aver age Β- Β distance, d , of 1.77 A. which, when corrected to a single distance, d , by the equation d = d - 0.6 log η (52), where the bond order, « , is 13/20, leads to a single bond-boron radius of 0.83 A. Moreover, the shortest B - B distance (1.60 A.) in all of the hydrides occurs in B H (29), which in all resonance structures has a single bond between these twb atoms. In addition the tetrahedrally bonded Β atom in tetragonal boron is 1.60 A. (32) from its neighboring Β atoms. One might be suspicious that this tetrahedral Β in tetragonal boron is ab normally compressed, or that some double bonding occurs in the short distance in Β Η ( we are at present studying the structure of B H C M e ) (59), but nevertheless, these short values support the short boron radius. In the halides, multiple bonding probably does occur, and this effect together with differences in the numbers and amounts of CI* · C l re pulsions leads to the progression of distances of 1.75, 1.73, 1.70, and 1.70 A. in, respectively, BC1 (58), B Cl4 (3), B^Cl^ (1)> a n d B C l (35), (acompound which certainly exists'.). The corresponding Β radii are 0.84, 0.82, and 0.79, obtained after subtraction of 0.99 for the CI radius and an electronegativity correction of 0.08 A. Remarkably enough, however, the B-Br distance (7) of 1.934 A. in terminally sub stituted BfcHg Br leads after subtraction of 1.11 A. for the Br radius and an electronegativity correction of 0.064 A. to a large Β radius of 0.89 A. Probably less multiple bonding occurs in BBr bonds as compared with that in BC1 bonds, but certainly there is no vacant orbital on the Β in BgHjjBr, as there is in the chlorides. A resonance or conjugation effect also appears to be present in the B - N bond of length 1. 523 A. in B H (NCCH ) (55), and in the B - N bond of length 1.507 A. in B H N C C H (62). After correction of 0.08 A. for electronegativity, these bonds lead to boron radii of 0.1,7 and 0.85 A . , respectively, but the effect of conjugation with the triple bond has not been included. Un fortunately, when conjugation with multiple bonds becomes an obvious possibility, the supposed state of hybridization of one of the bonded atoms becomes different from the usual situation; there has been a recent tendency to turn attention away from conjugation to hybridization in these cases. Finally, a resonance effect which stabilizes the bonding, and pre sumably shortens the B - B distances, has been proposed (10) mostly to account for the rather systematic requirement of a smaller Β radius in the boron hydrides themselves. The major point here is that the equation d = d - 0.6 log η is not equally valid for atoms in different coordination number (12). Even when all of these effects are taken into account, the boron r a dius obtained from different compounds still varies over several hun dredths of an Angstrom, and we conclude that bond distance discussions in boron chemistry still have to be restricted to very closely related compounds. 1 2


6

1 0

β

e

2

2

2

x

x

4

1 2

t 0

3

e

3

1 0

9

1 2

1 3

3

2

2

3

x


8

8

32

LIPSCOMB AND

LEW IN

Boron-Nitrogen

Table I.

315

Boron Radius

Bond Distance

Compound

Bonds

Reference Method

Radius

B...B B

B


B

2 H

2 4 F

B

2

C 1

4

B

4

C 1

4

8 8 B H NH B

C 1

3

B

K

7

3

10 16 H

C U

0.795

1.77 ± 0. 01

0.885

(28, 53) (26)

1.67 ±0.04

0.835

(60)

1.75 ± 0. 05

0.875

(3)

X

1.71 ±0.04

0.855 0. 90

(1) (36)

X

1.80 (av.) ± 0.04 1.744 ± 0.005

0.872

(51)

X

1.74 ± 0.06

0.87

(20)

X

1.80

0.835

(10)

X

(64)

X

b

2 6

2 10 10 B

H

B

(av.)

1.77 ± 0.01

2 12 12 H

s

1.589

6

0.83^

c

a

E a

a

x

X

B...N B .N U

1

(28)

s

0.79

(7,22)

X

0.91^

(63)

X

1.62 ± 0.15

0. 96

(4)

Ε

1. 50 ± 0. 02

0. 84

(27)

Ε

1.281

4

ΒΞΝ

1.45 ± 0.01

B - N cubic

1.57

(CH ) NBH 3

3

3

2 5 2 B H N(CH ) B

H

N H

1. 55 ± 0. 02

0.89

(27)

Ε

[(ΝΗ ) ΒΗ ] 0Γ

1. 58 ± 0. 02

0.92

(50)

Χ

H NB H

1.581 ± 0.003

0.921 0.94

(51) (30)

Χ

1.60 ± 0. 02 1.585 ± 0.03

0.925

(18)

χ

1.58 ± 0.03

0.92

(17)

χ

1.60

0.94

(16) (66)

χ

(61) (41)

χ

2

5

3

3

3

2

3

H NBF 3

3

3

3

H CH NBF 3

+

7

(CH ) NBF 3

2

2

2

3

(CH ) NB(CH ) 3

3

3

C H NBF 5

5

3

[BH N(CH ) ] 2

C

3

2 5 H

B H 9

B

1 ( )

N H

1 3

2

B

H

NCCH

3

H (NCCH ) 1 2

3

3

3

3 3 6 B C1 (NH)

B

3

2 8 11

B N (NCH ) 3

N

3

H

3

3

3

3

2

N H C

2 5 H

χ

χ

1.53

0.87

1.59 ± 0. 03

0.93

1.574 ± 0.009

0.914

1.581 ± 0.007

0.921

1.507 ± 0.01

0.85

1.523 ± .007

(62) (55)

χ

0.86

1.42 ± 0. 02

0.76

(6)

Ε

1.44 ± 0. 02

0.78

1.41 ± 0. 01

0.75

(5) (8)

Χ

1.2325

0.87^

(28)

1.2311

0.87

(28)

χ

χ Ε

Β. . . H

B H U

2


s s


Table I.

(BHV U

4

1.215

0.855

(28)

S

1.255 ± 0.02 1.19 ± 0.03

0.895 0.83

(15) (26)

NMR E

B

2 6

B

4 10

1.19

0.83

(49)

E

5 9

1.23 ± 0.07

0.87

(24)

X

1.22

0.86

(34)

M

1.20

0.84

(6)

E

1.262

0.70

(28)

S

H

H

B

H

B H (NCH ) 3


(Cont d.) f

3

3

3

Β . . . X , X=halogen B

F

U

BF

1

9

3

2 4 H N.BF

B

F

3

3

3 2- 3 (CH ) N-BF

H

C H

B F

3

3

H CCNBF ll 35 3

B

B

3

c l

BC1

B

3

2 4

C 1

C 1

3

(46)

S

(7)

E

1.32 ±0.04

0.76

(60)

X

1.39 ± 0.03

0.83 0.81

(30) (17)

X

1.37 1.39

0.83

(18)

X

1.32

0.76

(31)

X

1.7157

0.81

1.75 ± 0. 02

0.84

β

X

(28)

s

(2) (58)

X X

(39)

E

0.82

(3)

X

4

1.70 ± 0. 03

0.79 0.79

(1) (36)

X

1.70 ±0.04 1.755 ± 0.04

0.845

(45)

X

1.75 ± 0.01

0.84

(8)

X

1.887

0.837^

(28)

s

1.87 ± 0.02

0.82

(39)

E

1.934

0.884

(7)

M

2

2

(Cl B)

2

(NH)

Br

BBr, B

0.74 0.77

1.73 ± 0. 02

C 1

Β

1.30 1.33

4

8 8 C1 B(CH ) BC1

B

e

2 5 H

B r

2

X

Miscellaneous

B. . . C B(CH ) 3

1.56 ± 0. 02

3

C1 B(CH )BC1 2

2

(CH ) B H 3

2

2

4

2

0.83^

(39)

E

1.58 ± 0.05

0.85 0.88

(45) (25)

X

1.61


E

32

LIPSCOMB AND

LEW IN

Boron-Nitrogen

Table I.

317

Bonds

(Cont'd.)

B...O BO

1.2049

0.58

β

1.6091

0.61

e

(65)

S

1.925

0.925

(56)

X

1.88 ± 0.013

0.79

(47)

X

1.935 ± . 009

0.835

(21)

X

(28)

B... S BS B H [S(CH ) ] Downloaded by UNIV OF CALIFORNIA SAN DIEGO on August 17, 2015 | http://pubs.acs.org Publication Date: January 1, 1964 | doi: 10.1021/ba-1964-0042.ch032

1 Q

1 2

3

2

2

B...P (H N) PBH 2

3

3

[(H C) PBH ] 3

2

2

3

e

a. E electron diffraction, X x-ray diffraction, M microwave techniques, S other spectroscopic studies of gas molecules, NMR nuclear magnetic resonance. b. Three-center bridge H bond (B-H-B). C. (52, p. 255). 0. 835 = [l. 80 + 0. 6 log(ll/16)]/2 where 11/16 = bond order d. (52, p. 255). 0. 83 = [l. 77 + 0. 6 log (13/20)] /2 where 13/20 = bond order e. For all bonds between unlike atoms the formula (52, pp. 89, 224 ff)

D(A-B)

= r

A

- C p r ^ y

+ τ

β

is used,

where C = 0. 08 and

\ A~ B

A

X

r

Structural

X

c

0.77

0.5

Ν

0.74

1

Ο

0.74

1.5

Ρ

1.10

0.1

s

1.04

0.5

F

0.72

2

Cl

0.99

1

Br

1.11

0.8

H

0.37

0.1

Principles

The replacement of bridge H by a bridge-N(HR)-group has previ ously been found in B^Hg NH and Bg H NMe (27), but the possibility that the principle is more general has been suggested (41). There is a striking similarity of the bridged - N H - group tothe doubly hydrogen bridged — — — B H — - — group. In addition, Hoffmann has pointed out 2

5

2

2

2


318

ADVANCES

IN

CHEMISTRY

SERIES

to us the similarity of the internal bonding in E t N H B H NHEt to that in BgE (33) . Thus a second general principle of bonding is the sub stitution of - N H - for — — B H — — . But a third general principle may be of importance in understanding the instabilities of the Βγ and B hydrides. In EtNH B H N H E t , as in all other known hydrides, ions, and nitrogen derivatives, the open face is neatly filled with Η atoms about 2.0 to 2.6 A. apart. In addition, the terminal Η atoms point away from the polyhedral or molecular center, and are about 3 A . apart. A l l inter molecular contacts in all of the known crystal structures are Η · · · Η contacts. Thus in the larger polyhedral hydrides and derivatives, relatively few Η atoms are required to close the open regions with Η· · -H contacts. On the other hand, the small hydrides, like BgHg and B H , have already very close contacts which make attack by electron pair donors more difficult. It is the B and B hydrides in which the Η· · - H contacts across the open face of the molecule are possibly not sufficiently close to prevent ligand attack. While BH groups might allow more efficient filling of the open face, the proportion of BH groups, as compared with bridge Η atoms, is limited by the topological theory. Still another, and perhaps also important, feature of the boron frame work of the EtNI^BgHn NHEt molecule is the relatively long set of Β· · - B distances all around the periphery of the B group. Thus the average Β· · - B distance is 1.90 A . around the periphery, but 1.76 A . if peripheral Β· · - B bonds are omitted. One might ask if the open B and B would show this same suggestion of peripheral instability if they could be isolated. In summary, the striking stability of this nitrogen derivative of a clearly less stable boron hydride analog offers promise of a new area of research in the chemistry of boron-nitrogen compounds. 2

8

11

15

2

2


8

2

4

7

8

n

10

8

2

2

8

7

8

Table II. Β· · -B Distances (A) Compound

Edge 1.77 ± 0 . 0 1 ( 2 B )

Internal

Reference Method

B

2 6

(26)

Ε

B

3 8

1.80 1.77(B)

(54)

X

B

4 10

1. 842 ± 0. 005(B) 1.712 ± 0. 005

(48) (44)

X

H

H

H

B

5 9

B

5 11

B

6 10

H

H

H

EtNH B H NHEt 2

8

n

a

X

1.77 ± 0.02(B)

1.66 ± 0. 02[4]

(13)

X

1.76 ± 0.04(av)(B)

1.72 ± 0. 04Î3 1. 87 ± 0. 04[5

(38) (44)

X X

1. 794 ± 0. 009(B) 1.74 ± 0.010(B) 1.60 ± 0.01

1.74 ± 0. 0l[5 1.753 ± 0.009[ 5] 1.80 ± 0. 0l[5

(29)

X

1.922 ± 0. 009

1.730 ± 1.719 ± 1.723 ± 1.749 ± 1.773 ± 1.791± 1.800 ± 1.787 ± 1.808 ±

(41)

1. 1. 1. 1.

901 925 820 835

± ± ± ±

0. 009 0. 009 0. 008(B) 0. 009(B)

0. 009[5] 0.010 0. 008 0.009 0. 009 0,009 0. 009 0.007 0.01


32

LIPSCOMB

AND LEW IN

Boron-Nitrogen

Bonds

319

Table II. (Cont'd.) H

B H 9


1.95 1. 85 1.88 1.82 1.87 1.78

9 15

B

( B

1 3

(CH CN) 3

10 10 H

0.02 0. 02(B) 0.02(B) 0.02(B) 0.02(B) 0.02(B)

1.865 ± 0. 006 1.870 ± 0. 008 1. 842 i 0. 008(B)

10 14

B

10 12
2

B

l B

°- 18 22 B

H

(62)

± ± ± ± ±

0.011[5] 0.008 0.007 0.009 0.009 é 0.011 ± 0.006

1.77 ± 0. 02[5] 1.72 1.76 1.78 1.78 1.71 1.80

(37) (44)

1. 860 ± 0. 008 1. 849 ± 0. 008 1. 881 ± 0. 008(B)

1.766 ± 0.008Î5] 1.764 1.746 1.746 1.749 1.742 1.837

(55)

1.71 ± 0.06(B)

1.76 ± 0. 06(av.)[4] 1.74 ± 0. 0 6 ^

(20)

X

1.755 ± 0.007Î5 1.780 ± 0.007[5

(64)

X

1.791 1.784 1.776 1.757 1.798 1.799 1.790 1.816 1.777 1.737 1.760 1.759 1.783 1.719 1.788

(57)

X

1. 823 1. 790 1.782 1.838 1. 976 1. 968

H

1.731 1.766 1.745 1.760 1.722 1.785 1.825

2.01 ± 0.02 1.80 ± 0. 02(B) 1. 77 ± 0. 02(B)

H

18 22

(9)

(10)

< 12 12>" B

1.80±0.02[5] 1.73 1.76 1.74 1.77 1.83 1.80 1.76 1.77

1.73 ± 0. 03(av)[4 " 1.81 ± 0. 03(av) 5 1.86 ά 0. 04(av)[5

)

B

H

± ± ± ± ± ±

1.792 1.786 1.784 1.958 1.990

± ± ± ± ± ±

+ ± ± fc ±

0. 004(B) 0. 005(B) 0. 005(B) 0. 005 0. 004 0. 004

0.003(B) 0.004(B) 0.004(B) 0.003 0.006

± 0.004[5]

± 0.005 ± 0.004

± 0. 005 ± 0.004

1.794 ± 0.003 1.781 1.771 1.759 1.781 1.796 1.798 1.832 1.744 1.764


(14)

X X

320

A D V A N C E S IN C H E M I S T R Y SERIES

Table II.

(Cont'd.)

1.753 1.755 1.794 1.781 1.717 1.725


B

1.765 1.806 1.793 1.781 1.815 1.764 1.873 1.803 1.784

20 16 H

ι 0.006 * 0.004

(ii)

J 0.005 0.004

h 0.005

a. (B) t h r e e - c e n t e r ( B - H - B ) bridge bondj (2B) double bridge bond. b. N u m b e r in [ ] indicates coordination number of c e n t r a l o r internal boron, exclusive of t e r m i n a l H . C. Bond distances are averages of apex to equatorial, equatorial η to equatorial m , equatorial η to equatorial w, respectively. d. Apex to apex distance between two Β ^ Η » .

Acknowledgment The experimental study, carried out in collaboration with P. G. Simpson, will be published elsewhere. We acknowledge discussions with R. Hoffmann, and support of the experimental study by the Office of Naval Research and the U. S. Army Research Office (Durham). Literature

Cited

(1) Atoji, Masao, Lipscomb, W. Ν., Acta Cryst. 6, 547 (1953). (2) Atoji, Masao, Lipscomb, W. N., J. Chem. Phys. 27, 195 (1957). (3) Atoji, Masao, Wheatley, P. J., Lipscomb, W. Ν., Ibid., 27, 196-9 (1957). (4) Bauer, S. H., J. Am. Chem. Soc. 59, 1096 (1937). (5) Ibid., 60, 524 (1938). (6) Coffin, K. P., Bauer, S. H., J. Phys. Chem. 59, 193 (1955). (7) Cornwell, C. D., Ibid., 18, 1118 (1950). (8) Courson, D. L., Hoard, J. L., J. Am. Chem. Soc. 74, 1742 (1952). (9) Dickerson, R. E., Wheatley, P. J., Howell, P. Α . , Lipscomb, W. N., J. Chem. Phys. 27, 200 (1957). (10) Dobrott, R. D., Lipscomb, W. N., Ibid., 37, 1779 (1962). (11) Dobrott, R. D., Lipscomb, W. Ν., unpublished manuscript. (12) Donohue, J., J. Am. Chem. Soc. 85, 1238 (1963). (13) Dulmage, W. J., Lipscomb, W. Ν., Acta Cryst. 5, 260 (1952). (14) Folting, Κ., Simpson, P. G., Lipscomb, W. N., J. Chem. Phys., in press. (15) Ford, P. T., Richards, R. E., Discussions Faraday Soc. 19, 230 (1955). In Boron-Nitrogen Chemistry; Niedenzu, K.; Advances in Chemistry; American Chemical Society: Washington, DC, 1964.


32

LIPSCOMB AND LEW IN

Boron-Nitrogen

Bonds

321

(16) Geller, S., J. Chem. Phys. 32, 1569 (1960). (17) Geller, S., Hoard, J. L., Acta Cryst. 3, 131 (1950). (18) Ibid., 4, 399 (1951). (19) Graybill, B. M., Pitochelli, A. R., Hawthorne, M . F., Inorg. Chem. 1, 626 (1962). (20) Grimes, R., Wang, F. E., Lewin, R., Lipscomb, W. N., Proc. Natl. Acad. Sci. U. S. 47, 996 (1961). (21) Hamilton, W., Acta Cryst. 8, 199 (1955). (22) Hassel, Ο., Norsk Geol. Tidssk. 9, 226 (1926). (23) Hedberg, K . , J. Am. Chem. Soc. 74, 3486 (1956). (24) Hedberg, K . , Jones, M . E., Schomaker, V., Proc. Natl. Acad. Sci. U. S. 38, 679 (1952). (25) Hedberg, K . , Jones, M . E., Schomaker, V . , 2nd Intern. Congr. Crystallography, Stockholm, 1951. (26) Hedberg, K., Schomaker, V., J. Am. Chem. Soc. 73, 1482, (1951). (27) Hedberg, K., Stosick, A. J., Ibid., 74, 954 (1952). (28) Herzberg, G., "Spectra of Diatomic Molecules," 2nd ed., p. 509, Van Nostrand, New York, 1950. (29) Hirshfeld, F . L., Eriks, K . , Dickerson, R. E., Lippert,E. L., Jr., Lipscomb. W. N., J. Chem. Phys. 28, 56 (1958). (30) Hoard, J. L., Geller, S., Casimir, W. M., Acta Cryst. 4, 396 (1951). (31) Hoard, J. L., Owen, T. B., Buzzell, Α . , Salmon, Ο. N., Ibid., 3, 130 (1950). (32) Hoard, J. L., Hughes, R. E., Sands, D. E., J. Am. Chem. Soc. 80, 4507 (1958). (33) Hoffmann, R., Lipscomb, W. N., J. Chem. Phys. 37, 2872, (1962). (34) Hrostowski, H. J., Myers, J., Ibid., 22, 262 (1954). (35) Jacobson, R. Α . , Lipscomb, W. Ν., Ibid., 31, 605 (1959). (36) Jacobson, R., Lipscomb, W. N . , J. Am. Chem. Soc. 80, 5571 (1958). (37) Kasper, J. S., Lucht, C. M., Harker, D . , Acta Cryst. 3, 436 (1950). (38) Lavine, L . R., Lipscomb, W. N., J. Chem. Phys. 22, 614 (1954). (39) Levy, Η Α . , Brockway, L. O., J. Am. Chem. Soc. 59, 2085 (1937). (40) Lewin, R., Simpson, P. G . , Lipscomb, W. Ν., Ibid., 854, 478 (1963). (41) Lewin, R., Simpson, P.G., Lipscomb. W. N., J. Chem. Phys. 39, 1532 (1963). (42) Lipscomb, W. Ν., Proc. Natl. Acad. Sci. U. S. 47, 1791 (1961). (43) Mathews, F . S., Trefonas, L., Lipscomb, W. N., Acta Cryst. 14, 273 (1961). (44) Moore, Ε. Β., Jr., Dickerson, R. E., Lipscomb, W. N., J. Chem. Phys. 27. 209 (1957). (45) Moore, Ε. Β., Jr., Lipscomb, W. Ν., Acta Cryst. 9, 668 (1956). (46) Neilson, A. H . , J. Chem. Phys. 22, 659 (1954). (47) Nordman, C . E., Acta Cryst. 13, 535 (1960). (48) Nordman, C . E., Lipscomb, W. N., J. Chem. Phys. 21, 1856 (1953). (49) Ibid., 22, 614 (1954). In Boron-Nitrogen Chemistry; Niedenzu, K.; Advances in Chemistry; American Chemical Society: Washington, DC, 1964.


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(50) Nordman, C . E., Peters, C . R., J. Am. Chem. Soc. 81, 3551 (1959). (51) Nordman, C. E., Reimann, C . , Ibid., 81, 3538 (1959). (52) Pauling, L., "Nature of the Chemical Bond," 3rd ed., Cornell University Press, Ithaca, Ν. Υ., 1960. (53) Ibid., p. 317. (54) Peters, C. R., Nordman, C. E., J. Am. Chem. Soc. 82, 5758 (1960). (55) Reddy, J. M., Lipscomb, W. N.. J. Chem. Phvs. 31. 610 (1959). (56) Sands, D. E., Zalkin, Α . , Acta Cryst. 15, 410 (1962). (57) Simpson, P. G., Lipscomb, W. N . , J. Chem. Phys. 39, 26 (1963). (58) Spencer, C., Lipscomb, W. N . , J. Chem. Phys. 28, (1958). (59) Streib, W. Ε., Boer, F . P . , Lipscomb, W. N . , J. Am. Chem. Ser. 85, 2331 (1963). (60) Trefonas, L., Lipscomb, W. Ν., Ibid., 28, 54 (1958). (61) Trefonas, L., Mathews, F . S., Lipscomb, W. Ν., Acta Cryst. 14, 273 (1961). (62) Wang, F . Ε., Simpson, P. G . , Lipscomb, W. N., J. Chem. Phys. 35, 1335 (1961). (63) Wentorf, R. Α . , Jr., Ibid., 26, 956 (1957). (64) Wunderlich, J., Lipscomb, W. N., J. Am. Chem. Soc. 82, 4427 (1960). (65) Zeeman, P. B . , Can. J. Phys. 29, 336 (1951). (66) Zvonkova, Ζ. V . , Kristallografiya 1, 73 (1956). Received May 8, 1963.


Boron-Nitrogen Bonds in the Higher Boranes

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