Synthesis of permethyldodecaborate and paramagnetic...

Details Synthesis of permethyldodecaborate and paramagnetic... Synthesis of permethyldodecaborate and paramagnetic...

2000-05-23

2002-03-12

Vollano, Jean F. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Boron containing

C568S004000

Reexamination Certificate

active

06355840

ABSTRACT:

BACKGROUND
Hawthorne et al has reported the preparation of closo-1,12-C
2
B
10
(CH
3
)
12
and other octamethyl C
2
boranes.(Jiang, W., Knobler, C. B., Mortimer, M. D., Hawthorne, M. F.,
Angew. Chem
., 1995, 34, 1332.). The permethylated icosahedral carboranes [closo-CB
11
(CH
3
)
12
]
31
, and the uncharged blue radical closo-CB
11
(CH
3
)
12
derived from that anion, has been reported by Michl et al. (King, B. T., Zanousek, B. G., Trammell, M., Noll. B. C., Michl, J.,
J Am. Chem. Soc
., 1996, 118, 3313) Additionally, other persubstituted polyboron compounds are known.
The most prominent persubstituted polyboron compounds is the polyhydroxylated boron compound, boric acid, B(OH)
3
. Alkaline solutions of B(OH)
3
deposit Na
2
[B
4
O
5
(OH)
4
]·nH
2
O, which constitute two abundant boron minerals, kernite (n=2) and borax (n=8) (F. A. Cotton, G. Wilkinson,
Advanced Inorganic Chemistry
, 5th ed., Wiley, New York, 1988, pp. 164-169). Other common boron structures include the trigonal and tetrahedral boron-oxygen units common to borate minerals (G. A. Heller,
Top. Curr. Chem
. 1986, 131, 39-98) and the icosahedron. The allotropes of elemental boron, (J. Donohue,
The Structures of the Elements
, Wiley, New York, 1974, pp. 48-82), boron-rich solids (H. Hubert, B. Devouard, L. A. J. Garvie, M. O'Keeffe, P. R. Buseck, W. T. Petuskey, P. F. McMillan,
Nature
1998, 391, 376-378) and the parent anion of the polyhedral boranes, [closo-B
12
H
12
]
2−
(J. A. Wunderlich, W. N. Lipscomb,
J Am. Chem. Soc
. 1960, 82, 4427-4428) all contain B
12
icosohedra.
The charge-delocalized icosohedral ion [closo-B
12
H
12
]
2−
may be considered as the parent aromatic species for borane chemistry in a manner similar to that served by the benzene ring in organic (carbon) chemistry. Isoelectronic substitution of one or two :B-H vertices in [closo-B
12
H
12
]
2−
by :C-H
+
provides the aromatic derivatives [closo-1-CB
11
H
12
]
−
, and a set of three isomeric dicarbacarboranes (1,2− or ortho; 1,7− or meta; and 1,12− or para) closo-C
2
B
10
H
12
R (N. Grimes, Carboranes, Academic Press, New York, 1970, p. 8). Each of these isoelectronic derivatives of [closo-B
12
H
12
]
2−
, undergoes characteristic hydrogen-substitution reactions at their B-H vertices resulting in a huge number of known icosohedral species (Hawthorne, M. F., “Carborane Chemistry at Work and Play”, Proceedings of the Ninth International Meeting on Boron Chemistry published in
Advances in Boron Chemistry
, Seibert, W. (Ed.), The Royal Society of Chemistry, London, 1996, 261-272)
Of special interest are derivatives in which every available B-H vertex has been substituted. Thus, hydrophobic derivatives of [closo-B
12
H
12
]
2−
and [closo-1-CB
11
H
12
]
−
, and the three isomeric diboranes, such as [closo-B
12
Cl
12
]
2−
(Knoth, W. H., Miller, H. C., Sauer, J. C., Balthis, J. H., Chia, Y. T., Muetterties, E. L.,
Inorg, Chem
, 1964, 3, 159-167), [closo-CB
11
(CH
3
)
12
]
−
, (King, B. T.; Janousek, Z.; Grüner, B.; Trammell, M.; Noll, B. C.; Michl, J. J.
Am. Chem. Soc
. 1996, 118, 10902-10903) and closo-1,12-C
2
B
10
(CH
3
)
12
, (W. Jiang, C. B. Knobler, M. D. Mortimer, M. F. Hawthorne,
Angew. Chem
. 1995, 107, 1470-1473
;
Angew. Chem. Int. Ed. Engl
. 1995, 34, 1332-1334.) have been synthesized. The existence and formulation of similar highly substituted polyhedral borane derivatives having hydrophilic substituents, such as hydroxyl have most recently been demonstrated by Hawthorne and Peyman (“Aromatic Polyhedra Hydroxyborates: Bridging Boron Oxides and Boron Nitrides”,
Angew. Chem. Int. Ed
., 1999,38,1061-1064).
U.S. Pat. No. 3,551,120 to Miller, et.al. discloses the formation of numerous ionic icosahedral substituted boranes of the general formula M
a
(B
12
H
12-y
X
y
)
b
, with y=1-12, and U.S. Pat. No. 3,390,966 to Knofl et. al. discloses the formation of numerous ionic carboranes of the general formula M
a
(B
10
H
10-y
X
y
)
b
, with y=1-10, where b=1 to 3. However, examples of the analogous closo-borane dianions [closo-B
n
(CH
3
)
n
]
2−
(n=6-12) have not been reported.
Paramagnetic persubstituted polyhedral closo-boranes such as [closo-B
6
X
6
]
−
(Heinrich, A, Keller, H. L., Preetz, W. Z.
Naturforsch., Teil B
., 1990, 45, 184) and [closo-B
9
X
9
]
−
(Wong, E. H., Kabbani, R. M.,
Inorg. Chem
., 1990, 45, 184) where X is Cl, Br or I and [closo-CN
11
Me
12
]
−
(B. T. King, B. T., Noll, B. C., McKinley, A. J., Michl, J.,
J. Am. Chem. Soc
., 1996. 118. 10902) have also been reported. These species were obtained via metal-ion oxidation of the corresponding reduced borane clusters. In each case, solutions of these paramagnetic species are moderately stable, but decolorize after prolonged contact with air.
Many researchers have sought globular structures possessing both hydrophobic surfaces and extraordinary kinetic stability with which to synthesize supramolecular structures, weakly-coordinating anions and space-controlling drug components. The fullerenes, characterized by unique chemistry and physical properties, represent one family of such precursors. Another family of globular hydrophobes, referred to as “camouflaged” carboranes, have been described in the literature (Jiang, W.; Knobler, C. B.; Hawthorne, M. F.
Angew. Chem., Int. Ed. Engl
. 1995, 34, 1332-1334; King, B. T.; Janousek, Z.; Grüner, B.; Trammell, M.; Noll, B. C.; Michl, J.
J. Am. Chem. Soc
. 1996, 118, 3313-3314; Herzog, A.; Maderna, A.; Knobler, C. B.; Hawthorne, M. F.
Chem. Eur. J
. 1999, 5,1212-1217). These species may approach the van der Waals diameter of C
60
by attachment of methyl groups and functionalized methyl substituents to the icosahedral scaffolding of the aromatic [closo-C
n
B
12−n
H
12
]
n−2
(n=1 or 2). Whereas hydrophobic and amphiphilic derivatives of this sort are known with n=1 or 2, the fully methylated derivative of the parent species, dodecamethyl-closo-dodecaborate(2−), (n=0), has not been shown.


REFERENCES:
J Am. Chem. Soc. by Peymann et al 121 pp. 5601-5602, year 1999.*
Toralf Peymann, Carolyn B. Knobler, and M. Frederick Hawthorne, An Icosahedral Array of Methyl Groups Supported by an Aromatic Borane Scaffold: The [closo-B12(CH3) ]2-Ion, J. Am. Chem. Soc. May 29, 1999, 121, pp. 5601-5602.
Toralf Peymann, Carolyn B. Knobler, and M. Frederick Hawthorne, An Unpaired Electron Incarcerated within an Icosahedral Borane Cage: Synthesis and Crystal Structure of the Blue, Air-stable {[colso-B12(CH3) ]} radical, Chem. Commun., 1999, pp. 2039-2040.
M. Frederick Hawthorne, Broadening The Conflux of Boron and Carbon Chemistries,Dept. of Chemistry, University of California, Los Angeles, (presented in Durham, UK, Jul. 12, 1999), 8 pages.
Wei Jiang, Carolyn B. Knobler, and M. Frederick Hawthorne, Decakis (dchloromethyl)-1, 12-dicarba-closo-dodecaborane (12): CAmouflage of an Icosahedral Carborane By Using Bulky Functional Substituents, Angew. Chem. Int. Ed. Eng 1, 1996, 35, No. 21, pp. 2536-2537.
M.Frederick Hawthorbne, Carborane Chemistry At Work and At Play, Dept. of Chemistry and Biochemistry, The University of California, Los Angeles, (Presented at the Royal Society, UK 1996) pp. 1-17.

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