Bis(diorganylamino)dihalodiboroxanes as building blocks for boron heterocycles

Article abstract of DOI:10.1021/om960933x

Bis(diorganylamino)dihalo-1,3-diboroxanes 1 result from the controlled hydrolysis of (diorganylamino)dihaloboranes substituted with bulky dialkyl- or alkylarylamino groups. Dehalogenation with sodium/potassium alloy gives 1,4-dioxa-2,3,5,6-tetraborinanes 3 and, in the case of the di(s-butyl)amino groups, the corresponding oxadiborirane 4. If the dehalogenation is carried out in the presence of bi- or tricyclic aromatic compounds, addition of a B(NR₂)OB(NR₂) moiety is observed, and the corresponding 1,3-(1,2-dihydronaphthaline-1,2-diyl)diboroxane (5), 1,3-(9,10-dihydroanthracene-9,10-diyl)diboroxane (6), and 1,3-(9,10-dihydrophenanthrene-9,10-diyl)diboroxane (7) species are obtained. The compounds were characterized by NMR spectroscopy OH, ¹¹B, ¹³C), MS (EI and FI), and elemental analyses. X-ray crystal structure determinations are presented for 1a, 3a, 5a, and 6b.

Full text of DOI:10.1021/om960933x

2276
Organometallics 1997, 16, 2276-2284
Bis(d ior ga n yla m in o)d ih a lod ibor oxa n es a s Bu ild in g
Block s for Bor on Heter ocycles†
Walter Maringgele, Mathias Noltemeyer, and Anton Meller*
Institut fu¨r Anorganische Chemie der Universita¨t Go¨ttingen, Tammannstrasse 4,
D-37077 Go¨ttingen, Germany
Received November 4, 1996X
Bis(diorganylamino)dihalo-1,3-diboroxanes 1 result from the controlled hydrolysis of
(diorganylamino)dihaloboranes substituted with bulky dialkyl- or alkylarylamino groups.
Dehalogenation with sodium/potassium alloy gives 1,4-dioxa-2,3,5,6-tetraborinanes 3 and,
in the case of the di(s-butyl)amino groups, the corresponding oxadiborirane 4. If the
dehalogenation is carried out in the presence of bi- or tricyclic aromatic compounds, addition
of a B(NR2)OB(NR2) moiety is observed, and the corresponding 1,3-(1,2-dihydronaphthaline-
1,2-diyl)diboroxane (5), 1,3-(9,10-dihydroanthracene-9,10-diyl)diboroxane (6), and 1,3-(9,-
10-dihydrophenanthrene-9,10-diyl)diboroxane (7) species are obtained. The compounds were
characterized by NMR spectroscopy (1H, 11B, 13C), MS (EI and FI), and elemental analyses.
X-ray crystal structure determinations are presented for 1a , 3a , 5a , and 6b.
In tr od u ction
using a slight excess of the (dialkylamino)dihaloborane,
the formation of products indeed is controlled by steric
factors.
Kinetic stabilization by steric factors is responsible
for many unusual molecular structures and for reduced
activity of chemical moieties. In the case of boron-
nitrogen compounds, remarkable progress has been
achieved especially in the isolation of monomeric imi-
noboranes1 and aminoiminoboranes2 from which a rich
chemistry of reactions has developed. In contrast to
this, only a few attempts have been made to extend this
concept to boron-oxygen species. The extremely steri-
cally demanding tris(trimethylsilyl)methyl group was
used in the attempted stabilization of a BtO triple
bond; however, the intermediate could only be isolated
as the corresponding trimeric boroxine.3 The first three-
membered oxadiborirane ring4 resulted from the deha-
logenation of 1,3-dichloro-1,3-bis[tris(trimethylsilyl)-
methyl]-1,3-diboroxane,4 the only halogen-containing
diboryl oxide described so far. Replacement of bulky
organyl groups by sterically demanding diorganylamino
substituents bonded to boron leads to additional elec-
tronic stabilization of such compounds. The π-bonding
from the nitrogen to the boron atom diminishes the
electron deficiency of the latter, thus giving more
thermodynamic stability to classical structures. 1,3-
Diamino-1,3-dihalodiboroxanes have not been prepared
previously, and it is to be expected that bulky substit-
uents on the nitrogen atoms will influence their forma-
tion and chemistry.
In contrast to the stoichiometry defined by eq 1, the
molar equivalents used in the reaction are R2NBX2:H2O:
NEt3 ) 2:1:2. Upon distillation of the reaction mixture,
(1)
excess (dialkylamino)dihaloborane is recovered un-
changed as the fraction with the lowest boiling point.
Table 1 presents products and their yields obtained by
the hydrolysis of the (dialkylamino)dihaloboranes as
described before. Yield percentages are rounded figures;
for details, see Table 3. The yields do not add up to
100% due to distillation/sublimation losses.
The yields of the diboroxanes 1 are better (as to be
expected) for 1a -c compared to 1d -f. An X-ray struc-
ture analysis was performed for 1a (Figure 1). With
increasing steric hindrance by the alkyl groups, the yield
of the corresponding diboroxane 1 increases compared
to that of the boroxine 2. With R2 ) Pr2 or Me + cyclo-
C6H11, 1g was obtained in a small yield compared to
the main products 2g.5 Traces of 1i in relation to 2i
were identified by MS (m/ e 320 [M+]) in addition to
PhN(Me)BCl2 (m/ e 187) in a fraction subliming at 100
°C (0.0013 Torr). The yields are estimated in this case.
Cautious hydrolysis of Me2NBCl2 and Et2NBCl2 yielded
only the corresponding boroxines.6,7
Resu lts a n d Discu ssion
Upon cautious hydrolysis of (dialkylamino)dihalobo-
ranes in wet diethyl ether containing triethylamine,
† This paper is dedicated to Professor W. Siebert on the occasion of
his 60th birthday.
X Abstract published in Advance ACS Abstracts, April 15, 1997.
(1) Paetzold, P. Adv. Inorg. Chem. 1987, 31, 123.
(2) No¨th, H. Angew. Chem. 1988, 100, 1664; Angew. Chem., Int. Ed.
Engl. 1988, 27, 1603.
The reaction of the 1,3-(dialkylamino)-1,3-dichlorodi-
boroxanes 1a -c with sodium/potassium alloy in hexane
or octane gives rise to the 1,4-dioxa-2,3,5,6-tetrabori-
(3) Paetzold, P.; Neyses, S.; Ge´ret, L. Z. Anorg. Allg. Chem. 1995,
621, 732.
(4) Paetzold, P.; Ge´ret-Baumgarten, L.; Boese, R. Angew. Chem.
1992, 104, 1071; Angew. Chem., Int. Ed. Engl. 1992, 31, 1040.
(5) Cragg, R. H. J . Inorg. Nucl. Chem. 1968, 30, 711.
(6) Goubeau, J .; Keller, H. Z. Anorg. Allg. Chem. 1951, 267, 1.
(7) No¨th, H.; Schweizer, P. Chem. Ber. 1964, 94, 1464.
S0276-7333(96)00933-8 CCC: $14.00 © 1997 American Chemical Society

Bis(diorganylamino)dihalodiboroxanes
Organometallics, Vol. 16, No. 11, 1997 2277
Ta ble 1. P r od u cts of th e Hyd r olysis of Dia lk yla m in od ih a lobor a n es
1,3-bis(dialkylamino)-1,3-dihalodiboroxanes 1 yield % tris(dialkylamino)boroxines
yield %
X ) Cl
1a :
R ) iPr
X ) Cl
76
73
71
24
46
31
5
2a :
R ) iPr
17
21
17
44
23
29
85
40
>70
1b:
1c:
1d :
1e:
1f:
1g:
1h :
1i:
R ) iBu
X ) Cl
X ) Cl
X ) Br
X ) Br
X ) Br
X ) Cl
X ) Cl
X ) Cl
2b:
2c:
2a :
2b:
2c:
2g:
2h :
2i:
R ) iBu
X ) Cl
X ) Cl
X ) Br
X ) Br
X ) Br
X ) Cl
X ) Cl
X ) Cl
R ) sBu
R ) sBu
R ) iPr
R ) iPr
R ) iBu
R ) iBu
R ) sBu
R ) sBu
R ) nPr
R ) nPr
R)cyclo-C6H11
R2 ) Me + C6H5
38
∼ 1
R)cyclo-C6H11
R2 ) Me + C6H5
OB(H)NR2, and bis(dialkylamino)-1-chloro-1,3-diborox-
anes R2NB(H)OB(Cl)NR2.
If the dehalogenation of 1a or 1c with sodium/
potassium alloy (in hexane:dimethoxyethane ) 3:1) is
carried out in the presence of naphthalene, the 1,2-
diborylated 1,2-dihydronaphthalene derivatives 5 are
formed.
An X-ray crystal structure analysis was carried out
for 5a . 5a and 5c are the first 1,2-diborylated species
obtained from naphthalene. The 1,2-addition across the
F igu r e 1. Crystal structure of 1a with anisotropic dis-
placement parameters depicting 50% probability. The
hydrogen atoms have been omitted for clarity.
(3)
nane ring system (eq 2). This B4O2 ring so far has only
(2)
double bond of one ring of the naphthalene system
leaves the aromaticity of the second ring undisturbed.
Probably the formation of the five-membered ring in this
case favors the 1,2-addition. It should be noted that 1,4-
additions of boron species to naphthalene9,10 by one or
two boron atoms are well documented. Likewise, naph-
thalene species that are diborylated in the 1,8-positions
are obtained from the 1,8-dilithiated11-13 or the 1,8-
dimercurated14,15 precursors.
Reaction of the dehalogenation intermediates of 1a -c
with anthracene (eq 4) and analogously of 1b with
phenanthrene (eq 5) gives the corresponding addition
products 6 and 7 to the 9- and 10-position of the
aromatics. An X-ray crystal structure is provided for
6b. Hydrolysis of 5a , 6a , and 7 with aqueous KOH
yielded 1,2-dihydronaphthalene, 9,10-dihydroanthracene,
and 9,10-dihydrophenanthrene, respectively.
been reported in the dimeric condensate of 3,7-dihy-
droxy-1,8-dimethyl-closo-dicarbaundecaborane(11). No
X-ray structure analysis was reported.8
In the course of these reactions, the corresponding 2,3-
bis(dialkylamino)oxadiboriranes 4a -c are also formed.
While 4a and 4b can only be detected by field ionization
mass spectrometry (FI-MS) in the low-boiling forerun
of the distillation, 4c (where R is most bulky) can be
separated in a pure state. 4c is only the second
oxadiborirane described4 and the first one carrying
B-amino groups. Its unequivocal identification rests
upon its boiling point (compared to 3c) and the FI-MS
isotopic pattern. The radicals and/or biradicals formed
upon dehalogenation of the 1,3-bis(dialkylamino)-1,3-
dihaloboranes 1 apparently are highly reactive species.
Besides combining to give the corresponding 1,4-dioxa-
2,3,5,6-tetraborinanes 3 or diboriranes 4, respectively,
they can attack other radical species in the solution or
the solvent. This leads to numerous byproducts of the
reactions (eq 2) which were detected by FI-MS: tris-
(dialkylamino)boroxines [R2NBO]3 (2), bis(dialkylami-
no)boranes [R2N]2BH, bis(dialkylamino)chloroboranes
[R2N]2BCl, bis(dialkylamino)-1,3-diboroxanes R2NB(H)-
It should be noted that 9,10-dihydroanthracene de-
rivatives bridged in the 9,10-position by groups contain-
ing one, two, or three boron atoms as well as a B-N-B
sequence are described in a thesis16 but are not pub-
lished yet.
NMR Da ta . The 11B NMR chemical shifts of all
compounds described are in the expected range.17
(9) Meller, A.; Bromm, D.; Maringgele, W.; Bo¨hler, D.; Elter, G. J .
Organomet. Chem. 1988, 347, 11.
(10) Noltemeyer, M.; Pauer, F.; Bromm, D.; Meller, A. Acta Crys-
tallogr. 1990, C46, 1981.
(11) Katz, H. E. J . Am. Chem. Soc. 1985, 107, 1420.
(12) Katz, H. E. J . Org. Chem. 1985, 50, 5027.
(13) Hergel, A.; Pritzkow, H.; Siebert, W. Angew. Chem. 1994, 106,
1342; Angew. Chem., Int. Ed. Engl. 1994, 33, 1247.
(14) Letsinger, R. L.; Smith, J . M.; Gilpin, J .; McLean, D. B. J . Org.
Chem. 1965, 30, 807.
(15) Katz, H. E. Organometallics 1987, 6, 1134.
(16) No¨th, H.; Keisel, K., Dissertation of K. Keisel, Universita¨t
Mu¨nchen, 1992.
(17) No¨th, H.; Wrackmeyer, B. Nuclear Resonance Spectroscopy of
Boron Compounds; Springer-Verlag: Berlin, 1978.
(8) Mercer, G. D.; Scholer, F. R. Inorg. Chem. 1973, 12, 2102.

2278 Organometallics, Vol. 16, No. 11, 1997
Maringgele
ylboroxine23 (1.39(2) Å from electron diffraction) and
correspond to those in K3(BO2)3 (1.398(3) Å, by X-ray
diffraction).24,25 The B-B bond lengths (1.729(4) Å)
exceed those of a B-B bonded bis(dioxaborolanyl)
(1.711(6) Å)26 by 0.018 Å, probably due to the better
π-donation from the N-substituent in 3a . Also the B-B
distances in 1,2,4,5-tetrakis(dimethylamino)-1,2,4,5-tet-
raborinane (1.711(2) Å)27 and in 1,2-bis(dimethylamino)-
1,2-diphenyldiborane(4) (1.714(4) Å)28 are shorter com-
pared to the B-B bond in 3a where the boron atoms
carry N- and O-substituents. The B-N distances
(1.400(3) Å, mean value) are in the normal range
generally found in aminoboranes,28 borazines,20 or the
just-mentioned diborane(4) derivative.27
(4)
(5)
In 5a , bond lengths of the B2O skeleton correspond
to those in 3a ; however, the BOB angle (111.2(2)°) is
rather small, due to the incorporation of the diboroxane
system into the five-membered ring. The B-C distances
(1.602(3) and 1.626(5) Å) are comparable to those in
other five-membered ring systems containing a boron
atom and a conjugated double bond.29 The five-
membered and six-membered (nonaromatic) rings form
an envelope conformation with C3 (0.46 Å) and C9b
(0.55 Å) folded above the plane formed by the other
atoms in the rings.
The compounds 1c, 1f, 3c, 4c, 5c, and 6c carrying
di-s-butylamino groups contain chiral C atoms. There-
fore splitting of the signals for the NCHCH3 group is
1
expected in the H and 13C NMR spectra. However, the
observed splitting (four signals in the 13C NMR and
doublets or unresolved multiplets in the 1H NMR
spectra) could also be caused by sterically hindered
rotation about the (BN) bonds.
6b shows an almost planar arrangement of the C2B2O
bridge (the deviation is only 5.3°). Bond lengths are in
the usual range. The BOB angle is widened to 131.4(1)°
and also the OBC angles are 118.9(1)°, mean value) due
to the bridging function between C9 and C10 of the
dihydroanthrancene.
Cr ysta l Str u ctu r es. Selected bond lengths and
angles are compiled in Table 2.
In the structure of 1a , the boron atoms are sur-
rounded in an almost planar, distorted trigonal environ-
ment by the oxygen, nitrogen, and chlorine atoms. The
molecule, however, is twisted by 79.1° about the oxygen
atom. Bond lengths of the B-O bonds (1.367(3) Å)
correspond to those observed in Me2BOMe by electron
diffraction18 (1.363(2) Å, mean value) while in tetrakis-
(amino)diboroxane {[(Me3Si)2N][Me3SiNH]B}2O they
are slightly longer (1.385(3) Å) by X-ray diffraction.19
The B-N distances (1.383(3) Å, mean value) are short-
ened compared to 2,4,6-trichloroborazine (1.413(10) Å),20
thus indicating that π-bonding is mainly concentrated
in this bond. On the other hand, the B-Cl bonds appear
rather long (1.809(3) Å, mean value). Typical B-Cl
distances are 1.760(15) Å (in 2,4,6-trichloroborazine,
X-ray diffraction data,20 and 1.750(5) Å in MeBCl2, from
the microwave spectrum.21 The B-Cl distance in 1a
corresponds to a species carrying chlorine atoms bonded
to tetracoordinated boron as in 1,5-dichloro-3,7-bis-
(trifluoromethyl)-4,8-bis(2′,6′-dimethylphenyl)-2,6,9-tri-
oxa-1,5-diborabicyclo[3.3.1]nonadiene with a B-Cl dis-
tance of 1.817(3) Å (mean value).22
Exp er im en ta l Section
All reactions were performed in an inert atmosphere of dry
nitrogen in dry solvents saturated with nitrogen. Most high-
vacuum distillations or sublimations were performed using a
rotating three-bulb system. Bulb volumes (100, 250, 500 mL)
were adapted to the amount of the reaction products. The
system was rotated by a motor adapted from a Bu¨chi Ro-
tavapor. In these cases, boiling point (bp) and sublimation
point (sublp) temperatures are those of the air bath. Melting
points were determined in sealed capillaries. In the case of
melting point (mp) (dec) the temperature given is when
decomposition starts. Elemental analyses were performed by
the analytical laboratory of the institute of inorganic chemistry
and by Mikroanalytisches Labor Beller, Go¨ttingen, Germany.
NMR spectra were recorded on Bruker AM-250 or MSL-400
instruments. Heteroelement spectra were recorded in the
proton-decoupled mode. Solvents and standards used were as
follows: 1H, 13C, CDCl3/TMS internal; 11B, CDCl3/F3B‚OEt2
external. Assignments of 13C signals were made by distor-
tionless enhancement of polarization transfer (DEPT, 100.60
MHz). Mass spectra were obtained in a Varian CH5 instru-
ment (electron impact (EI) 70 eV and field ionization (FI)) and
a Finnigan MAT 8230 (EI, 70 eV) spectrometer.
In 3a , the two oxygen atoms are positioned on a 2-fold
axis. The conformation is twisted in relation to the
boron atoms, which show deviations of 0.3-0.4 Å from
the least-squares plane. The BOB bond angles are
widened (117.3(3)°, mean value) compared to the OBB
angles (112.2(2)°). The B-O distances (1.408(3) Å,
mean value) are ∼0.02 Å longer than in 2,4,6-trimeth-
Starting materials were prepared according to the following
(23) Bauer, S. H.; Beach, J . Y. J . Am. Chem. Soc. 1941, 63, 1394.
(24) Zachariasen, W. H., J . Chem. Phys. 1937, 5, 919.
(25) Schneider W.; Carpenter, G. B. Acta Crystallogr. B 1970, 26,
1189.
(18) Gundersen, G.; J onvik, T.; Seip, R. Acta Chem. Scand. A 1981,
35, 325.
(19) Paciorek, K. J . L.; Kratzer, R. H.; Kimble, P. F.; Nakahara, J .
H.; Wynne, K. J .; Day, C. S. Inorg. Chem. 1988, 27, 2432.
(20) Courson, D. L.; Hoard, J . L. J . Am. Chem. Soc. 1952, 74, 1742.
(21) Cox, A. P. J . Mol. Struct. 1983, 97, 61.
(26) No¨th, H. Z. Naturforsch. B 1984, 39, 1463.
(27) Fisch, H.; Pritzkow, H.; Siebert, W. Z. Naturforsch. B: Chem.
Sci. 1988, 43, 658.
(28) Moezzi, A.; Olmstead, M. M.; Power, P. P. J . Chem. Soc. Dalton
Trans. 1992, 2429.
(29) Meller, A.; Bo¨ker, C.; Seebold, U.; Bromm, D.; Maringgele, W.;
Heine, A.; Herbst-Irmer, R.; Pohl, E.; Stalke, D.; Noltemeyer, M.;
Sheldrick, G. M. Chem. Ber. 1991, 124, 1907.
(22) Clegg, W.; Noltemeyer, M.; Sheldrick, G. M.; Maringgele, W.;
Meller, A. Z. Naturforsch. B 1980, 35, 1499.

Bis(diorganylamino)dihalodiboroxanes
Organometallics, Vol. 16, No. 11, 1997 2279
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles (d eg) for 1a , 3a , 5a , a n d 6b
Compound 1a
O(1)-B(1)
N(1)-C(4)
N(2)-C(10)
1.367(3)
1.479(3)
1.481(3)
O(1)-B(2)
N(1)-C(1)
N(2)-C(7)
1.367(3)
1.490(3)
1.498(3)
B(1)-N(1)
B(2)-N(2)
1.382(3)
1.384(3)
B(1)-Cl(1)
B(2)-Cl(2)
1.808(3)
1.810(3)
B(1)-O(1)-B(2)
B(1)-N(1)-C(4)
N(2)-B(2)-Cl(2)
134.2(2)
123.1(2)
120.6(2)
O(1)-B(1)-N(1)
B(1)-N(1)-C(1)
B(2)-N(2)-C(10)
123.5(2)
123.1(2)
123.6(2)
O(1)-B(1)-Cl(1)
O(1)-B(2)-N(2)
B(2)-N(2)-C(7)
115.6(2)
123.7(2)
121.5(2)
N(1)-B(1)-Cl(1)
O(1)-B(2)-Cl(2)
120.7(2)
115.7(2)
Compound 3a
O(1)-B(1)
N(1)-C(11)
1.406(3)
1.480(3)
B(1)-N(1)
O(2)-B(2)
1.397(3)
1.411(3)
B(1)-B(2)
B(2)-N(2)
1.729(4)
1.402(3)
N(1)-C(14)
1.471(3)
B(1)-O1)-B(1)#1
B(1)-N(1)-C(14)
N(2)-B(2)-B(1)
116.9(3)
119.8(2)
129.6(2)
N(1)-B(1)-O(1)
B(1)-N(1)-C(11)
O(2)-B(2)-B(1)
119.2(2)
123.9(2)
111.8(2)
N(1)-B(1)-B(2)
B(2)#1-O(2)-B(2)
127.5(2)
117.7(3)
O(1)-B(1)-B(2)
N(2)-B(2)-O(2)
112.7(2)
118.4(2)
Compound 5a
O(1)-B(2)
1.393(4)
1.505(4)
1.401(4)
1.483(4)
O(1)-B(10)
C(3)-C(9B)
C(9A)-C(9B)
N(1)-C(14)
1.402(4)
1.558(4)
1.515(4)
1.487(4)
B(2)-N(2)
C(4)-C(5)
C(9B)-B(10)
1.403(4)
1.333(4)
1.626(5)
B(2)-C(3)
C(5)-C(5A)
B(19)-N(1)
1.602(4)
1.469(5)
1.395(4)
C(3)-C(4)
C(5A)-C(9A)
N(1)-C(11)
B(2)-O(1)-B(10)
C(4)-C(3)-C(9B)
C(4)-C(5)-C(5A)
O(1)-B(10)-C(9B)
B(2)-N(2)-C(21)
111.2(2)
110.3(2)
121.2(3)
109.0(3)
122.8(2)
O(1)-B(2)-N(2)
C(4)-C(3)-B(2)
C(9A)-C(5A)-C(5)
B(10)-N(1)-C(11)
123.1(3)
105.9(2)
118.8(3)
122.3(2)
O(1)-B(2)-C(3)
C(9B)-C(3)-B(2)
N(1)-B(10)-O(1)
B(10)-N(1)-C(14)
109.1(3)
101.9(2)
120.0(3)
122.8(2)
N(2)-B(2)-C(3)
C(5)-C(4)-C(3)
N(1)-B(10)-C(9B)
B(2)-N(2)-C(24)
127.7(3)
123.3(3)
131.0(3)
121.6(2)
Compound 6b
O(1)-B(1)
B(2)-N(2)
C(8A)-C(10)
1.389(2)
1.406(2)
1.525(2)
O(1)-B(2)
B(2)-C(10)
C(9)-C(9A)
1.389(2)
1.599(2)
1.519(2)
B(1)-N(1)
C(8)-C(8A)
C(10)-C(10A)
1.408(2)
1.385(2)
1.519(2)
B(1)-C(9)
C(8A)-C(9A)
1.605(2)
1.403(2)
B(1)-O(1)-B(2)
O(1)-B(2)-N(2)
B(1)-N(1)-C(15)
131.41(14) O(1)-B(1)-N(1)
117.2(2) O(1)-B(2)-C(10)
120.93(13) C(8)-C(8A)-C(9A) 119.7(2)
116.3(2)
O(1)-B(1)-C(9)
118.58(14) N(1)-B(1)-C(9)
B(1)-N(1)-C(11)
125.1(2)
125.25(14)
C(9A)-C(8A)-C(10) 117.15(14)
119.37(14) N82)-B(2)-C(10) 123.4(2)
C(8)-C(8A)-C(10) 123.1(2)
C(9A)-C(9)-C(4A) 109.35(13) C(9A)-C(9)-B(1)
C(8A)-C(10)-B(2) 110.27(13)
106.44(13) C(4A)-C(9)-B(1) 109.95(12) C(10A)-C(10)-B(2) 105.69(13)
Ta ble 3. Yield sa of Com p ou n d s 1 a n d 2 in Rela tion to Ster ic Hin d r a n ce
g % of
diboroxane 1
boroxine 2
dihalogeno(diorganylamino)borane (0.5 mol)
amt (g)
(i-Pr)2NBCl2
90.5
105
105
135.5
145.5
145.5
90.5
59/76
67/73
1a
1b
1c
1d
1e
1f
11/17
2a
2b
2c
2a
2b
2c
2g
2h
(i-Bu)2NBCl2
(s-Bu)2NBCl2
(i-Pr)2NBBr2
(i-Bu)2NBBr2
(s-Bu)2NBBr2
(n-Pr)2NBCl2
(cyclo-C6H11)2NBCl2
15.5/20.8
12.6/16.7
42.6/44.2
17.6/22.7
22.5/29
65.5/71
23.4/24
52/45.8
45/30.5
4.5/5
1g
1h
54/85
41/39.8
130.5
45/38
a
The yields are based on the dihalogeno(diorganylamino)borane.
references: (i-Pr)2NBCl2,30 (n-Pr)2NBCl2,31 (i-Bu)2NBCl2,32 (s-
Bu)2NBCl2,32 c-C6H11N(CH3)BCl2,33,34 (i-Pr)2NBBr2,35 Me2-
NBCl2,36 Et2NBCl2,31 and (c-C6H11)2NBCl2.37 (i-Bu)2NBBr2 (A)
and (s-Bu)2NBBr2 (B) were prepared by a general procedure
for the preparation of aminodihalogenoboranes.38
nium bromide was removed by filtration in a N2 atmosphere.
The solvent was then evaporated under reduced pressure and
collected in a cold trap. The residue was distilled using a 10
cm Vigreux column and gave 256.5 g (85.8%) of A and 242.6
(81.1%) of B.
Am in obr om obor a n es A a n d B. Gen er a l P r oced u r e. A
mixture of 1 mol of triethylamine (101 g) and 1 mol (129 g) of
the starting amine (diisobutylamine for A or di-s-butylamine
for B) was added with stirring to 1.0 mol (250.5 g) of BBr3 in
1 L CCl4 at 0 °C within 2 h. After addition of the mixture of
the amines, the slurry was refluxed for 4 h. Triethylammo-
Dibr om o(d iisobu tyla m in o)bor a n e (A). Colorless liquid
(bp 100 °C (7.5 Torr)). Anal. Calcd for C8H18BBr2N (298.86):
C, 32.15; H, 6.08. Found: C, 32.61; H, 6.41. 1H NMR: δ 0.90
3
3
(d, J HH ) 6.8 Hz, CHCH3, 12H), 1.98 (sept, J HH ) 6.8 Hz,
3
CHCH3, 2H), 3.20 (d, J HH ) 6.8 Hz, CHCH2, 4H). 13C NMR:
δ 19.91 (CHCH3), 27.12 (CHCH3), 58.16 (NCH2). 11B NMR: δ
25.9 (h1/2 ) 90 Hz).
(30) Gerrard, W.; Hudson, H. R.; Mooney, E. F. J . Chem. Soc. 1960,
5168; 1962, 113.
(31) Witman, E. D., U.S. Borax & Chemical Corp. Brit. 977.066,
1964); U.S. Appl., March 20, 1962.
(32) Maringgele, W.; Meller, A. Z. Naturforsch. B: Chem. Sci. 1989,
44, 67-73.
(33) Baudler, M.; Marx, A. Z. Anorg. Allg. Chem. 1981, 474, 18.
(34) Ba¨chle, H. T.; Becher, J . Spectrochim. Acta 1965, 21, 579.
(35) No¨th, H.; Staudigl, R. Chem. Ber. 1982, 115, 3011.
(36) Skinner, H. A.; Smith, N. B. J . Chem. Soc. 1954, 2324.
(37) Geymayer, P.; Rochow, E. G. Monatsh. Chem. 1966, 97, 437.
(38) Niedenzu, K.; Dawson, J . W. Boron-Nitrogen Compounds;
Springer-Verlag: Berlin, 1965.
Dibr om o(d i-s-bu tyla m in o)bor a n e (B). Colorless liquid
(bp 108 °C (7.5 Torr)). Anal. Calcd for C8H18BBr2N (298.86):
3
Br, 53.47. Found: Br, 52.70. 1H NMR: δ 0.90 (t, J HH ) 7.0
Hz, CH2CH3, 6H), 1.05-1.75 (br, CH3CH2, CHCH3, CHCH3),
2.13 (br, CHCH3), 3.12 (br, CHCH3), 4.30 (br, CHCH3). 13C
NMR: δ 11.72 (CH2CH3), 19.70 (CHCH3), 27.57, 30.05 (CH2-
CH3), 54.02, 60.99 (CHCH3). 11B NMR: δ 24.0 (h1/2 ) 95 Hz).
1,3-Bis(dialkylam in o)-1,3-dih alodibor oxan es (1a-h ) an d
2,4,6-Tr is(d ior ga n yla m in o)bor oxin es (2a -c,g,h ). Typ ica l
P r oced u r e for Ca u t iou s Hyd r olysis of Dih a lo(d ia lk yl-

2280 Organometallics, Vol. 16, No. 11, 1997
Maringgele
a m in o)bor a n es: P r ep a r a tion of 1,3-Bis(d iisop r op yla m i-
n o)-1,3-d ich lor o-1,3-d ibor oxa n e (1a ) a n d 2,4,6-Tr is(d i-
isop r op yla m in o)bor oxin e (2a ). A mixture of 4.5 g (0.25
mol) H2O, 50.5 g (0.5 mol) of triethylamine and 800 mL of dry
diethyl ether was added within 3 h to a stirred solution of 91
g (0.5 mol) of dichloro(diisopropylamino)borane in 500 mL of
hexane at -60 °C. Stirring was continued for 3 h at -60 °C
and after warming to room temperature for another 10 h.
Triethylammonium chloride was removed by filtration under
N2. The solvents were evaporated under reduced pressure and
collected in a trap cooled by liquid N2. From the remaining
residue are recovered 12 g (13.2%) of dichloro(diisopropylami-
no)borane by distillation (bp 60 °C (7.5 Torr)) in a rotating
three-bulb tube system. Yields of 59 g (76%) of 1a (sublp 80-5
°C (0.001 Torr)) and 2a (sublp 100-120 °C (0.001 Torr)) were
obtained by subsequent sublimation in the three-bulb system.
1b-h and 2b-h were prepared analogously in the 0.5 mol
scale; the yields are summarized in Table 3.
Upon cautious hydrolysis of Me2NBCl2, Et2NBCl2, MeN-
(C6H5)BCl2, and Me(cyclo-C6H11)NBCl2, only the boroxine
derivatives[Me2NBO]3,[Et2NBO]3,[Me(Ph)NBO]3,and[Me(cyclo-
C6H11NBO]3 were obtained. These reactions were conducted
starting from 100 mmol of the corresponding dichloro(diorgan-
ylamino)borane in 100 mL of hexane, 0.9 g (50 mmol) of H2O,
10.1 g (100 mmol) of NEt3 and 200 mL of Et2O at -60 °C. The
boroxine derivatives were isolated by sublimation and distil-
lation, respectively, in the rotating three-bulb system. In the
case of dichloro(dipropylamino)borane, the diboroxane deriva-
tive 1g was obtained in a minute yield compared to the
boroxine 2g.
for C16H36B2Br2N2O (453.90): C, 42.34; H, 7.99; N, 6.17.
Found: C, 42.75; H, 8.25; N, 6.30. MS: EI m/ e (rel intensity)
454 [M+], 411 (100); FI 454 (100) [M+]. 1H NMR: δ 0.83-
0.90 (m, CHCH3, 24H), 1.75-1.95 (m, CHCH3, 4H), 2.75 (d,
3J HH ) 7.4 Hz, NCH2, 4H), 2.86 (d, 3J HH ) 7.5 Hz, NCH2, 2H),
3
2.98 (d, J HH ) 7.5 Hz, NCH2, 2H). 13C NMR: δ 20.02, 20.15,
20.39 (CHCH3), 26.55, 26.89, 27.20 (CHCH3), 53.13, 53.90,
55.73 (NCH2). 11B NMR: δ 23.0 (h1/2 ) 720 Hz).
1,3-Dib r om o-1,3-b is(d i-s-b u t yla m in o)-1,3-d ib or oxa n e
(1f). Yellowish liquid (bp 95 °C (0.001 Torr)). Anal. Calcd
for C16H36B2Br2N2O (453.90): C, 42.34; H, 7.99; Br, 35.21; N,
6.17. Found: C, 42.84; H, 8.29; Br, 34.87; N, 6.26. MS: EI
m/ e (rel intensity) 425 (100) [M - C2H5]+; FI 454 (100). 1H
3
3
NMR: δ 0.90 (t, J HH ) 6.9 Hz, CH2CH3, 6H), 0.91 (t, J HH
)
3
7.0 Hz, CH2CH3, 3H), 0.92 (t, J HH ) 7.0 Hz, CH2CH3, 3H),
3
3
1.14 (d, J HH ) 6.3 Hz, CHCH3, 3H), 1.16 (d, J HH ) 6.3 Hz,
3
3H), 1.30 (d, J HH ) 6.7 Hz, CHCH3, 6H), 1.38-1.78 (m, CH2-
CH3, 8H), 3.05 (br, CHCH3, 2H), 3.86 (br, CHCH3, 2H). 13C
NMR: δ 11.51, 11.65, 12.03, 12.09 (CH2CH3), 19.82, 20.36,
20.59, 20.95 (CHCH3), 28.39, 30.02 (CH2CH3), 52.08, 55.98
(CHCH3). 11B NMR: δ 22.7 (h1/2 ) 450 Hz).
1,3-Dich lor o-1,3-bis(dipr opylam in o)-1,3-dibor oxan e (1g).
Yellowish liquid (bp 80 °C (0.001 Torr)). Anal. Calcd for
C
12H28B2Cl2N2O (308.89). C, 46.66; H, 9.14; N, 9.06. Found:
C, 46.12; H, 9.19; N, 9.18. MS: EI 308 (10) [M+], 279 (100);
FI 308 (100). 1H NMR: δ 0.85 (t, J HH ) 7.5 Hz, CH2CH3,
3
3
6H), 0.87 (t, J HH ) 7.5 Hz, CH2CH3, 6H), 1.50 (m, CH2CH3,
8H), 3.00 (4 overlaping d, NCH2, 8H). 13C NMR: δ 11.24, 11.30
(CH2CH3), 22.69, 22.73 (CH2CH3), 48.55, 49.60 (NCH2). 11B
NMR: δ 23.6.
1,3-Dich lor o-1,3-b is(d iisop r op yla m in o)-1,3-d ib or ox-
a n e (1a ). White solid (sublp 80-85 °C (0.0075 Torr); mp (dec)
from 185 °C). Anal. Calcd for C12H28B2Cl2N2O (308.89): C,
46.66; H, 9.14; Cl, 22.95; N, 9.06. Found: C, 46.66; H, 9.25;
Cl, 22.70; N, 9.02. MS: EI m/ e (rel intensity) 308 (10) [M+],
293 (100); FI: 308 (100) [M+]. 1H NMR: δ 1.12 (d, 3J HH ) 6.9
1,3-Dich lor o-1,3-b is(d icycloh exyla m in o)-1,3-d ib or ox-
a n e (1h ). White solid (sublp 170 °C (0.001 Torr); mp dec
starting at 320 °C). Anal. Calcd for C24H44B2Cl2N2O (469.15):
C, 61.44; H, 9.45; N, 5.97. Found: C, 61.59; H, 9.62; N, 6.05.
MS: EI m/ e (rel intensity) 468 (50) [55]; FI 468 (100). 1H
NMR: δ 1.00-1.30 (m, CH2, 8H), 1.45-1.90 (m, CH2, 32H),
3.00 (br, CH, 2H), 3.40 (br, CH, 2H). 13C NMR: δ 25.58, 26.38,
26.60, 32.41, 33.29 (CH2), 55.45, 57.15 (CHCH2). 11B NMR: δ
23.9 (h1/2 ) 250 Hz).
3
Hz, CHCH3, 12H), 1.14 (d, J HH ) 6.8 Hz, CHCH3, 12H), 3.40
3
3
(sept, J HH ) 6.9 Hz, CHCH3, 2H), 3.80 (sept, J HH ) 6.8 Hz,
2H). 13C NMR: δ 21.99 (CHCH3), 23.14 (CHCH3), 45.32
(CHCH3), 47.46 (CHCH3). 11B NMR: δ 23.9 (h1/2 ) 230 Hz).
1,3-Dich lor o-1,3-b is(d i-i-b u t yla m in o)-1,3-d ib or oxa n e
(1b). Colorless liquid (bp 105 °C (0.0075 Torr)). Anal. Calcd
for C16H36B2Cl2N2O (365.00): C, 52.65; H, 9.94; Cl, 19.43; N,
7.67. Found: C, 52.41; H, 9.99; Cl, 19.11; N, 7.72. MS: EI
m/ e (rel intensity) 364 (7) [M+], 321 (100); FI 364 (100) [M+].
1H NMR: δ 0.86 (d, 3J HH ) 6.6 Hz, CHCH3, 12H), 0.88 (d, 3J HH
) 6.7 Hz, CHCH3, 12H), 1.80-1.95 (m, CHCH3, 4H), 2.82 (d,
2,4,6-Tr is(d iisop r op yla m in o)bor oxin e (2a ).39,40 Color-
less crystalline substance (sublp 100 °C (0.001 Torr); mp 204
°C). Anal. Calcd for C18H42B3N3O3 (380.99): B, 8.51; N, 11.03.
Found: B, 8.42; N, 11,12. MS: EI m/ e (rel intensity) 381 (40)
[M+]; FI 381 (100). 1H NMR: δ 1.16 (d, 3J HH ) 7 Hz, CHCH3,
36H), 3.57 (sept, 3J HH ) 7 Hz, CHCH3, 6H). 11B NMR: δ 20.5
(h1/2 ) 120 Hz).
2,4,6-Tr is(d i-i-bu tyla m in o)bor oxin e (2b). Yellowish liq-
uid (bp 120 °C (0.001 Torr)). Anal. Calcd for C24H54B3N3O3
(465.14): C, 61.97; H, 11.70; N, 9.03. Found: C, 61.45; H,
11.86; N, 8.97. MS: EI m/ e (rel intensity) 465 (5) [M+], 422
(100); FI 465 (100). 1H NMR: δ 0.86 (d, 3J HH ) 6.6 Hz, CHCH3,
3
3J HH ) 7.5 Hz, NCH2, 4H), 2.91 (d, J HH ) 7.60 Hz, NCH2,
4H). 13C NMR: δ 19.97, 20.08 (CHCH3), 26.52, 26.73 (CHCH3),
53.65, 54.61 (NCH2). 11B NMR: δ 24.4 (h1/2 ) 550 Hz).
1,3-Bis(d i-s-b u t yla m in o)-1,3-d ich lor o-1,3-d ib or oxa n e
(1c). Yellowish liquid (bp 100 °C (0.0075 Torr)). Anal. Calcd
for C16H36B2Cl2N2O (365.00): C, 52.65; H, 9.94; Cl, 19.43; N,
7.67. Found: C, 52.43; H, 10.02; Cl, 19.12; N, 7.75. MS: EI
m/ e (rel intensity) 364 (5) [M+], 321 (100); FI 364 (100) [M+].
3
36H), 1.84 (m, CHCH3, 6H), 2.80 (d, J HH ) 7.3 Hz, 12H). 13C
NMR: δ 20.47 (CHCH3), 27.30 (CHCH3), 53.22 (NCH2). 11B
NMR: δ 23.9 (h1/2 ) 1700 Hz).
2,4,6-Tr is(d i-s-bu tyla m in o)bor oxin e (2c). Yellow oil (bp
3
3
1H NMR: δ 0.80 (t, J HH ) 6.7 Hz, CH2CH3, 6H), 0.82 (t, J HH
165 °C (0.0075 Torr)). Anal. Calcd for
C24H54B3N3O3
3
) 7.4 Hz, CH2CH3, 3H), 0.83 (t, J HH ) 7.0 Hz, CH2CH3, 3H),
(465.14): C, 61.97; H, 11.70; N, 9.03. Found: C, 61.39; H,
11.84; N, 9.01. MS: EI m/ e (rel intensity) 465 (8) [M+], 436
1.05-1.18 (m, CHCH3, 12H), 1.33-1.60 (m, CH2CH3, 8H), 3.00
(br, NCH, 2H), 3.50 (br, NCH, 2H). 13C NMR: δ 11.72, 11.88,
12.00, 12.24 (CH2CH3), 20.11, 20.64, 20.76, 20.96 (CHCH3),
28.71, 29.67 (CH2CH3), 51.85, 52.16, 54.05 (NCH). 11B NMR:
δ 24.1 (h1/2 ) 390 Hz).
3
(100); FI 465 (100). 1H NMR: δ 0.86 (t, J HH ) 7.5 Hz,
3
CH2CH3, 18H), 1.12 (d, J HH ) 6.5 Hz, CHCH3, 9H), 1.14 (d,
3J HH ) 6.0 Hz, CHCH3, 9H), 1.45-1.65 (m, CH2CH3, 12H), 3.20
(br, NCH, 6H). 13C NMR: δ 12.05, 12.10, 12.16, 12.22
(CH2CH3), 20.62, 20.74 (CHCH3), 29.56, 29.69 (CH2CH3), 50.37,
50.62 (NCH). 11B NMR: δ 22.6 (h1/2 ) 2200 Hz).
1,3-Dib r om o-1,3-b is(d iisop r op yla m in o)-1,3-d ib or ox-
a n e (1d ). White solid (sublp 80 °C (0.001 Torr); mp 137-146
°C). C12H28B2Br2N2O (397.78). MS: EI m/ e (rel intensity) 398
(10), 383 (100); FI 383 (100, M+). 1H NMR: δ 1.17 (d, 3J HH ) 6.7
2,4,6-Tr is(d ip r op yla m in o)bor oxin e (2g)2. Yellowish liq-
uid (bp 85 °C (0.001 Torr)). C18H42B3N3O3 (380.98). MS: EI
m/ e (rel intensity) 381 (5) [M+], 352 (100); FI 381 (100). 1H
3
Hz, CHCH3, 12H), 1.26 (d, J HH ) 6.7 Hz, CHCH3, 12H), 3.55
(m, CHCH3, 2H), 4.10 (m, CHCH3, 2H). 13C NMR: δ 21.73,
23.59 (CHCH3), 45.48, 49.56 (CHCH3). 11B NMR: δ 22.3 h1/2
) 300 Hz). 1d contained boroxine 2a .
3
NMR: δ 0.85 (t, J HH ) 7.1 Hz, CH2CH3, 18H), 1.30-1.60 (m,
CH2CH3, 12H), 2.75-2.95 (m, NCH2, 12H). 13C NMR: δ 11.64,
1,3-Dib r om o-1,3-b is(d i-i-b u t yla m in o)-1,3-d ib or oxa n e
(39) Seebold, U. Diplomarbeit Universita¨t Go¨ttingen, 1989.
(1e). Yellowish liquid (bp 130 °C (0.0075 Torr)). Anal. Calcd
(40) Bromm, D. Diplomarbeit Universita¨t Go¨ttingen, 1987.

Bis(diorganylamino)dihalodiboroxanes
Organometallics, Vol. 16, No. 11, 1997 2281
Ta ble 4. Ed u cts a n d P r od u cts to 5-7
11.69 (CH2CH3), 23.38, 23.47 (CH2CH3), 47.66, 49.15 (NCH2).
11B NMR: δ 22.30 (h1/2 ) 620 Hz).
g (mmol) of
g (mmol) of 1,3-dichloro-
2,4,6-Tr is(dicycloh exylam in o)bor oxin e (2h ). White solid
(sublp 270 °C (0.001 Torr), not melting below 310 °C). Anal.
Calcd for C36H66B3N3O3 (621.87): C, 69.54; H, 10.69; N, 6.76.
Found: C, 70.21; H, 10.78; N, 6.69. MS: EI m/ e (rel intensity)
621 (100); FI 621 (100). 1H NMR: δ 1.10-1.30 (m, CH2), 1.60
(m, CH2), 1.72 (m, CH2), 1.90 (m, CH2), 2.62 (m, CHCH2). 13C
NMR: δ 25.93, 26.82, 33.46 (CH2), 53.30, 53.48 (CHCH3). 11B
NMR: δ 20.9.
compd aromatic educt
1,3-diboroxane 1
yield (g (%))
5c
6a
6b
6c
6h
7
25.6 (200)
36.5 (200)
36.5 (200)
36.5 (200)
36.5 (200)
36.5 (200)
36.5 (100) 1c
30.8 (100) 1a
36.5 (100) 1b
36.5 (100) 1c
46.9 (100) 1h
36.5 (100) 1b
12.6 (30.0)
14.5 (35.0)
13.7 (29.0)
12.35 (26.2)
18.10 (31.4)
16.30 (34.5)
Typ ica l Deh a logen a tion Rea ction of Bis(d ia lk yla m i-
n o)d ih a lo-1,3-d ibor oxa n es: P r ep a r a tion of 2,3,5,6-Tet-
r akis(di-s-bu tylam in o)-1,4-dioxa-2,3,5,6-tetr abor in an e (3c)
a n d 2,3-Bis(d i-s-bu tyla m in o)-1-oxa -2,3-d ibor ir a n e (4c). A
73 g (200 mmol) sample of 1c was added under vigorous
stirring to a suspension of 500 mmol of Na/K alloy (13 g of K,
4 g of Na) in 650 mL of hexane at 25 °C within 1 h. After
refluxing the reaction mixture for 60 h, the excess of alkali
metals and salts was removed by filtration. The solvent was
evaporated under reduced pressure and collected in a trap
cooled by liquid N2. The residue was fractionated by distilla-
tion and sublimation, respectively, in a rotating three-bulb
system at 0.001 Torr to give four fractions with the following
boiling point ranges: 50-100, 100-120, 140-150, and 165-
170 °C. The first fraction (50-100 °C) contained bis(di-s-
butylamino)borane, bis(di-s-butylamino)chloroborane, and 4c.
A 1.3 g (4.5%) sample of 4c (bp 60 °C, 0.001 Torr) was obtained
by redistillation of this fraction in a microdistillation ap-
paratus. The fraction bp 100-120 °C contained a mixture of
bis(di-s-butylamino)-1,3-diboroxane and bis(di-s-butylamino)-
1-chlorodiboroxane, which were identified by their mass
spectra. Attempted separation was unsuccessful. Redistilla-
tion of the fraction bp 140-150 °C afforded 27 g (45%) of tris-
(di-s-butylamino)boroxine 2c (a yellow, viscous liquid), bp 145-
150 °C (0.001 Torr). Resublimation of the fraction bp 165-
170 °C gave 4.7 g (7.99%) of 3c (sublp 170 °C (0.001 Torr)).
Certainly there are considerable losses in the purification
process by distillation and sublimation. Replacing the solvent
by octane did not change the composition of the obtained
fractions significantly, the main product in this case was also
tris(di-s-butylamino)boroxine, 2c.
Syn th eses of 3a a n d 3b. A 61.6 g (0.2 mol) sample of 1a
and 73 g (0.2 mol) of 1b, respectively, were treated with 0.5
mol of Na/K alloy (13 g of K, 4 g of Na) in 650 mL of hexane.
The reactions were carried out as described for 3c. However,
4a and 4b could not be obtained in a pure state (identification
by mass spectrometry) by the subsequent distillation and
sublimation process. The other byproducts of these reactions
are the corresponding bis(dialkylamino)boranes and bis(di-
alkylamino)chloroboranes (bp 50-70 °C (0.001 Torr)), bis-
(dialkylamino)-1,3-diboroxanes and bis(dialkylamino)-1-chloro-
1,3-diboroxanes (fraction bp 70-90 °C (0.001 Torr)). As for
3c, the main products are the boroxines 2a (19.5 g, 39%) and
2b (28.9 g, 47%). 3a (sublp 175 °C (0.001 Torr); 5.46 g,
(11.47%) and 3b (sublp 200 °C (0.001 Torr); 6.12 g, (10.41%),
which are both colorless solids, were obtained by sublimation.
Crystals for the X-ray structure of 3b were obtained by
crystallization from hexane.
(dec) from 245 °C). Anal. Calcd for C32H72B4N4O2 (588.19):
C, 65.34; H, 12.34; N, 9.52. Found: C, 65.76; H, 12.45; N, 9.51.
MS: EI m/ e (rel intensity) 588 (15) [M+], 545 (100); FI 588
(100). 1H NMR (toluene-d8): δ 0.72 (d, 3J HH ) 6.6 Hz, CHCH3,
3
24H), 0.84 (d, J HH ) 6.6 Hz, CHCH3, 24H), 1.70-1.90 (m,
3
CHCH3, 8H), 2.78 (d, J HH ) 7.3 Hz, NCH2, 16H). 13C NMR:
δ 19.92, 20.52, 20.71 (CHCH3), 25.96, 27.10 (CHCH3), 50.62,
56.70 (CH2CH). 11B NMR: δ 34.6 (h1/2 ) 1150 Hz).
2,3,5,6-Tetr a k is-(d i-s-bu tyla m in o)-1,4-d ioxa -2,3,5,6-tet-
r a bor in a n e (3c). White solid (sublp 170 °C (0.001 Torr); mp
(dec) at 243 °C). Anal. Calcd for C32H72B4N4O2 (588.19): C,
65.34; H, 12.34; N, 9.52. Found: C, 65.80; H, 12.41; N, 9.48.
MS: EI m/ e (rel intensity) 588 (20) [M+], 559 (100); FI 588
(100). 1H NMR: δ 0.75-1.40 (m, CH3, CH2, 64H), 1.50 (br,
NCH, 2H), 1.95 (m, NCH, 2H), 2.65 (m, NCH, 2H), 3.35 (br,
NCH, 2H). 13C NMR: δ 12.34, 12.40, 12.56, 12.61, 12.77,
12.90, 12.97, 13.03 (CH2CH3), 20.09, 20.40, 20.62, 20.71, 20.86,
20.88, 21.11, 21.32 (CHCH3), 50.22, 50.78, 50.95, 51.04, 56.67,
56.74, 56.81, 56.89 (CHCH3). 11B NMR: δ 35.7 (h1/2 ) 1200
Hz).
2,3-Bis(d i-s-bu tyla m in o)-1-oxa -2,3-d ibor ir a n e (4c). Col-
orless liquid (bp 60 °C (0.075 Torr)). Anal. Calcd for
C
16H36B2N2O (294.09). C, 65.35; H, 12.34; N, 9.52. Found:
C. 65.15; H, 12.52; N, 9.43. MS: EI m/ e (rel intensity) 265
3
(100) [M - C2H5]+; FI 294 (100). 1H NMR: δ 0.88 (t, J HH
)
3
7.3 Hz, CH2CH3, 12H), 1.17 (d, J HH ) 6.7 Hz, CHCH3, 3H),
3
3
1.20 (d, J HH ) 6.6 Hz, CHCH3, 6H), 1.23 (d, J HH ) 6.7 Hz,
3
CHCH3, 3H), 1.35-1.75 (m, CH2CH3, 8H), 2.90 (sept, J HH
)
3
6.6 Hz, CHCH3, 1H), 2.92 (sept. J HH ) 6.7 Hz, CHCH3, 1H),
3.42 (sept, J HH ) 6.5 Hz, CHCH3, 2H). 13C NMR: δ 11.35,
3
11.37, 11.39, 11.76 (CH2CH3), 20.97, 21.04, 24.01, 24.10
(CH2CH3), 29.35, 29.37, 31.77, 32.10 (CH2CH3), 53.30, 54.03,
55.23, 55.87 (NCH). 11B NMR: δ 36.2 (h1/2 ) 490 Hz).
Typ ica l Rea ction of Alk a li Meta l Com p lexes of Ar o-
m a t ic Com p ou n d s w it h Bis(d ia lk yla m in o)d ih a lo-1,3-
dibor oxan es: 1,3-Bis(diisopr opylam in o)(1,2-dih ydr on aph -
th a len e-1,2-d iyl)-1,3-d ibor oxa n e (5a ). A 25.6 g (200 mmol)
sample of naphthalene was added during 30 min to a stirred
suspension of 200 mmol Na/K alloy (5.2 g K, 1.6 g Na) in a
solvent mixture of 1,2-dimethoxyethane (250 mL) and hexane
250 mL) at 25 °C. The start of the reaction was indicated by
black coloring of the suspension. Stirring was continued for
24 h at room temperature. In due course, 30.8 g (100 mmol)
of 1 in 200 mL of hexane was added within 1 h. The
exothermic reaction was accompanied by a color change from
black to grey. After refluxing for 6 h the slurry was filtered,
the solvents were evaporated from the filtrate under reduced
pressure, and the residue fractionated by sublimation in a
rotating three-bulb system. As a first fraction, 12.5 g of a
mixture of naphthalene and dihydronaphthalene sublimed/
distilled, respectively, at 60-80 °C (0.001 Torr); 11.7 g, (32%)
5a was obtained by subsequent sublimation at 120 °C (0.001
Torr).
2,3,5,6-Tet r a k is(d iisop r op yla m in o)-1,4-d ioxa -2,3,5,6-
tetr a bor in a n e (3a ). White solid (sublp 175 °C (0.001 Torr);
mp 185 °C (dec)). Anal. Calcd for C
24H56B4N4O2 (475.97): C,
60.56; H, 11.86; N, 11.77. Found: C, 60.32; H, 12.05; N, 11.72.
MS: EI m/ e (rel intensity) 476 (45) [M+], 433 (100); FI 476
(100). 1H NMR (toluene-d8): δ 1.06 (d, 3J HH ) 6.6 Hz, CHCH3,
5c, 6a -c, 6h , and 7 were prepared in the same manner.
For educt quantities and product yields, see Table 4. As for
5a for 5c, the color turns from black to grey by addition of the
1,3-dihalo-1,3-diboroxane derivative; in the reactions of an-
thracene and phenanthrene, respectively, it turns from black
to green. The starting materials were partially recovered in
the low subliming fractions at 60-80 (for 5 and 7) and 100-
120 °C (0.001 Torr) (for 6). Dihydronaphthalene and dihy-
droanthracene were identified by their mass spectra in these
3
3
12H), 1.09 (d, J HH ) 6.7 Hz, CHCH3, 12.H), 1.43 (d, J HH
)
3
6.8 Hz, CHCH3, 12H), 1.51 (d, J HH ) 6.8 Hz, CHCH3, 12H),
3
3
3.05 (sept, J HH ) 6.8 Hz, CHCH3, 4H), 3.78 (sept, J HH ) 6.7
Hz, CHCH3, 4H). 13C NMR: δ 21.53, 23.53, 23.91, 25.00
(CHCH3), 43.95, 50.62 (CHCH3). 11B NMR: δ 35.6 (h1/2 ) 480
Hz).
2,3,5,6-Tetr a k is-(d i-i-bu tyla m in o)-1,4-d ioxa -2,3,5,6-tet-
r a bor in a n e (3b). White solid (sublp 200 °C (0.001 Torr); mp

2282 Organometallics, Vol. 16, No. 11, 1997
Maringgele
F igu r e 4. Crystal structure of 5a with anisotropic dis-
placement parameters depicting 50% probability.
F igu r e 2. Crystal structure of 3a with anisotropic dis-
placement parameters depicting 50% probability. The
hydrogen atoms have been omitted for clarity.
F igu r e 3. Crystal structure of the skeleton of 3a seen from
the direction of the 2-fold axis (tilted by 5°). Anisotropic
displacement parameters depicting 50% probability.
fractions. The yields are summarized in Table 4. Crystals
for the X-ray analysis of 5a and 6b were obtained by crystal-
lization from n-hexane.
F igu r e 5. Crystal structure of 6b with anisotropic dis-
placement parameters depicting 50% probability. The
hydrogen atoms have been omitted for clarity.
1,3-Bis(d iisop r op yla m in o)-(1,2-d ih yd r on a p h t h a len e-
1,2-d iyl)-1,3-d ibor oxa n e (5a ). Colorless crystals (sublp 120
°C (0.001 Torr); mp 116-119 °C). Anal. Calcd for C22H36B2N2O
(366.16): C, 72.16; H, 9.92; N, 7.65. Found: C, 72.25; H, 10.04;
N, 7.72. MS: EI m/ e (rel intensity) 366 (10) [M+]; FI 366 (100).
1H), 2.65 (m, NCH, 2H), 2.85 (br, BCH×e2 1H), 3.35 (m, NCH,
2H), 5.70-5.90 (m, 3-H, 1H), 6.30-6.40 (m, 4-H, 1H), 6.85-
7.05 (m, 5-H bis 8-H, 4H). 13C NMR: δ 11.84, 11.89, 11.95,
12.01 (CH2CH3), 19.26, 20.50, 20.62, 20.78 (CHCH3), 21.31,
27.91, 27.95, 29.10 (CH2CH3), 33.0 (br, B-C), 50.31, 50.39,
50.49, 50.55 (CHCH3), 124.67, 125.21, 127.25, 128.28, 128.31,
130.93 (3-C bis 8-C), 133.49, 139.12 (Cq). 11B NMR: δ 36.3
(h1/2 ) 940 Hz).
1,3-Bis(d iisop r op yla m in o)-(9,10-d ih yd r oa n t h r a cen e-
9,10-d iyl)-1,3-d ibor oxa n e (6a ). Light brown solid (bp 135
°C (0.001 Torr); mp 174-6 °C). Anal Calcd for C26H38B2N2O
(416.22): C, 75.04; H, 9.32; N, 6.69; Found: C, 74.67; H, 9.42;
N, 6.69. MS: EI m/ e (rel intensity) 416 (30) [M+]; FI 416 (100).
1H NMR: δ 0.98 (d, 3J HH ) 6.9 Hz, CHCH3, 12H), 1.43 (d, 3J HH
) 6.9 Hz, CHCH3, 12H), 3.80 (m, CHCH3, 4H), 4.12 (s, 9-H
and 10-H, 2H), 6.98-7.40 (m, 1-H to 4-H and 5-H to 8-H, 8H).
13C NMR: δ 22.26, 25.00 (CHCH3), 43.21, 44.45 (CHCH3),
43.70 (br, B-C, 9-C and 10-C), 124.85, 125.53 (1-C, 2-C), 140.85
(Cq). 11B NMR: δ 28.2 (h1/2 ) 680 Hz).
3
3
1H NMR: δ 0.46 (d, J HH ) 6.7 Hz, 3H), 0.98 (d, J HH ) 6.7
3
3
Hz, 3H), 1.12 (d, J HH ) 6.7 Hz, 3H), 1.16 (d, J HH ) 6.7 Hz,
3
3
3H), 1.20 (d, J HH ) 6.8 Hz, 3H), 1.31 (d, J HH ) 6.8 Hz, 6H),
1.33 (d, 3J HH ) 6.7 Hz, 3H), 2.35 (dvt, 2H, 3J HH ) 8.5 Hz, 3J HH
4
3
) 2.7 Hz, J HH) 2.8 Hz, 1H), 2.66 (d, 1H, J HH ) 8.5 Hz, 1H),
3
3
3.03 (sept, J HH ) 6.8 Hz, 1H, CHCH3), 3.24 (sept, J HH ) 6.8
Hz, CHCH3, 1H), 3.65 (sept, 3J HH ) 6.7 Hz, CHCH3, 1H), 3.70
3
3
(sept, J HH ) 6.7 Hz, CHCH3, 1H), 5.78 (dvd, 3-H, J HH ) 9.5
3
3
4
Hz, J HH ) 2.7 Hz, 1H), 6.37 (dvd, 4-H, J HH ) 9,5 Hz, J HH
)
2.8 Hz, 1H), 6.90-7.10 (m, possible 5-8, 4H). 13C NMR: δ
21.2, 21.7, 22.4, 22.5, 24.0, 24.1 (CHCH3), 29.2 (br, 2-C), 33.2
(br, 1-C), 43.6, 43.9, 47.2, 48.4 (CHCH3), 126.9 (4-C), 124.8,
125.3, 126.2, 128.2 (5-C to 8-C), 130.7 (3-C), 133.5, 138.5 (Cq).
11B NMR: δ 36.3 (h1/2 ) 500 Hz).
1,3-Bis(d i-s-bu tyla m in o)-(1,2-d ih yd r on a p h th a len e-1,2-
d iyl)-1,3-d ibor oxa n e (5c). White solid (sublp 140 °C (0.001
Torr); mp (dec) from 196 °C). Anal. Calcd for C26H44B2N2O
(422.26): C, 73.96; H, 10.50; N, 6.63. Found: C, 73.45; H,
10.70; N, 6.55. MS: EI m/ e (rel intensity) 422 (15) [M+], 393
(100),; FI 393 (100). 1H NMR: δ 0.85 (m, CH2CH3, 12H), 1.05-
1.30 (m, CHCH3, 12H), 1.55 (m, CH2CH3, 8H), 2.35 (br, BCH,
1,3-Bis(d i-i-bu tyla m in o)-(9,10-d ih yd r oa n th r a cen e-9,10-
d iyl)-1,3-d ibor oxa n e (6b). Yellowish, highly viscous sub-
stance (bp 150 °C (0.001 Torr)) which crystallizes slowly (mp
112-3 °C) after crystallization from n-hexane. Anal. Calcd
for C30H46B2N2O (472.31): C, 76.29; H, 9.82; N, 5.93. Found:
C, 75.98, H, 10.02; N, 5.97. MS: EI m/ e (rel intensity) 472(20)

Bis(diorganylamino)dihalodiboroxanes
Organometallics, Vol. 16, No. 11, 1997 2283
Ta ble 5. Cr ysta l Da ta a n d Str u ctu r e Refin em en t for 1a , 3a , 5a , a n d 6b
1a
3a
5a
6b
formula
fw
C12H28B2Cl2N2O
308.88
153(2)
0.71073
monoclinic
P21/n
10.992(1)
15.150 (1)
11.063(1)
90
C24H56B4N4O2
475.97
213(2)
0.71073
monoclinic
C2/c
9.673(1)
28.584(8)
12.6070(1)
90
C22H36B2N2O
366.15
153(2)
0.71073
monoclinic
P21/n
11.236(5)
6.163(3)
32.606(9)
90
97.17(9)
90
C30H46B2N2O
472.31
153(2)
0.71073
monoclinic
P21/c
18.317(2)
9.080(1)
18.930(3)
90
temp (K)
wavelength (Å)
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
94.16(1)
90
1837.5(3), 4
1.117
111.55(1)
90
3242.1(10), 4
0.9756
111.81(1)
90
2923.0(6), 4
1.073
γ (deg)
volume (Å3), Z
2240(2), 4
1.086
0.064
density (calcd) (Mg m-3
)
abs coeff (mm-1
)
0.348
0.059
0.063
F(000)
664
1056
800
1032
crystal size (mm)
θ-range for data coll (deg)
limiting indices
0.70 × 0.70 × 0.50 0.50 × 0.40 × 0.40 0.70 × 0.70 × 0.50 0.80 x 0.80 × 0.70
3.69-24.98
-13 e h e 13
-8 e k e 18
-13 e l e 13
5195
3.76-22.53
-10 e h e 10
-3 e k e 30
-13 e l e 13
2440
3.54-22.54
-12 e h e 2
-6 e k e 6
-35 e l e 35
3379
3.59-22.46
-19 e h e 19
-3 e k e 9
-12 e l e 20
3822
no. of rflns coll
no. of indep rflns
3206
2125
2874
3788
R(int)
0.0293
0.0629
0.0744
0.1022
refinement method full-matrix-least squares on F2
g1
0.030
0.076
0.110
0.066
g2
2.050
2.260
1.830
0.954
data/restraints/parameters
goodness of fit on F2
final R indices [I > 2σ(I)]
3200/0/180
1.118
2121/0/163
1.038
2869/0/252
1.040
3782/0/324
1.038
R1 ) 0.0488
wR2 ) 0.1167
R1 ) 0.0571
wR2 ) 0.1276
0.390 and -0.215
R1 ) 0.0545
wR2 ) 0.1327
R1 ) 0.0804
wR2 ) 0.1576
0.209 and -0.187
R1 ) 0.0662
wR2 ) 0.1730
R1 ) 0.0802
wR2 ) 0.1963
0.344 and -0.267
R1 ) 0.0417
wR2 ) 0.1066
R1 ) 0.0473
wR2 ) 0.1161
0.181 and -0.185
R indices (all data)
largest diff peak and hole (e Å-3
)
3
[M+], 429(100); FI 472(100). 1H NMR: δ 0.60 (d, J HH ) 6.7
(100). 1H NMR: δ 0.50-0.95 (m, CHCH3, 24H), 1.65-1.85 (m,
3
3
3
Hz, CHCH3, 12H), 0.96 (d, J HH ) 6.7 Hz, CHCH3, 12H), 1.76
CHCH3, 4H), 2.60 (d, J HH ) 6.6 Hz, 2H), 2.65 (d, J HH ) 6.6
Hz, 4H), 2.76 (d, 3J HH ) 7.3 Hz, 4H), 2.83 (s, B-CH, 2H), 7.05-
7.60 (m, 1-H bis 8-H). 13C NMR: δ 19.64, 19.73, 19.86, 20.50
(CHCH3), 33.1 (br, BC), 53.02, 53.07 (NCH2), 123.80, 125.84,
126.96, 128.76 (1-C bis 8-C), 134.65, 139.80 (Cq). 11B NMR: δ
35.90 (h1/2 ) 750 Hz).
(sept v. t, CHCH3, zu d bei 0.60, 2H), 1.91 (sept v. t, CHCH3,
3
zu d. bei 0.96, 2H), 4.03 (s, 9-H, 10-H, 2H), 2.75 (d, J HH ) 7.6
Hz, NCH2, zu 1.76, 4H), 3.05 (d, 3J HH ) 7.4 Hz, NCH2, zu 1.91,
4H), 7.03 (m, 2-H, 4H), 7.13 (m, 1-H, 4H). 13C NMR: δ 19.9,
20.6 (CHCH3), 26.8, 28.2 (CHCH3), 41.4 (B-C), 52.6, 55.0
(NCH2), 125.0 (2-C), 125.3 (1-C), 140.2 (Cq). 11B NMR: δ 28.2
(h1/2 ) 1000 Hz).
Hyd r olytic r ea ction s of 5a , 6a a n d 7. To 5 g 5a , 6a , and
7, respectively, dissolved in n-hexane, 50 mL of 30 °C aq-
ueous, KOH was added and the mixture refluxed for 8 h. The
hexane phase was separated and the aqueous phase extracted
with diethyl ether. The etheric phase and the hexane phase
were combined and dried by MgSO4. After filtration from
MgSO4 and removal of the solvents, the residue was distilled
and yielded 1,2-dihydronaphthalene for the reaction of 5a ,
9,10-dihydroanthracene for 6a , and 9,10-dihydrophenanthrene
for 7, identified by their mass spectra.
1,3-Bis(di-s-bu tylam in o)-(9,10-dih ydr oan th r acen e-9,10-
d iyl)-1,3-d ibor oxa n e (6c). Ockre oil, solidifies upon storing
(bp 170 °C (0.001 Torr); mp 101-4 °C). Anal. Calcd for
C
30H46B2N2O (472.31): C, 76.29; H, 9.82; N, 5.93. Found: C,
76.55; H, 9.97; N, 5.84. MS: EI m/ e (rel intensity) 472 (35)
[M+], 443 (100); FI 472 (100). 1H NMR: δ 0.50-2.00 (m, CH3,
CH2, 32H), 3.60 (br, NCH, 4H), 4.10 (s, 9-H, 10-H, 2H). 13C
NMR: δ 11.62, 12.13, 12.53, 12.71, 14.10 (CH3), 22.68, 29.74,
31.62 (CH2), 43.19 (BC), 50.25, 50.48, 51.03, 51.27 (NCH),
124.81, 125.45 (1-C, 2-C), 140.77 (Cq). 11B NMR: δ 28.3 (h1/2
) 1300 Hz).
1,3-Bis(d icycloh exyla m in o)-(9,10-d ih yd r oa n th r a cen e-
9,10-d iyl)-1,3-d ibor oxa n e (6h ). White solid (sublp 250 °C
(0.001 Torr); mp 213-218 °C). Anal. Calcd for C38H54B2N2O
(576.48): C, 79.17; H, 9.44; N, 4.86. Found: C, 78.63; H, 9.52;
N, 4.69. MS: EI m/ e (rel intensity) 576 (5) [M+], 138 (100).
1H NMR: δ 0.95-2.25 (m, CH2, 40 H), 2.95 (br, CHCH2, 2H),
3.60 (br, CHCH3, 2H), 4.20 (s, 9-H and 10-H, 2H), 7.05 (m,
2-H, 4H), 7.27 (m, 4-H, 4H). 13C NMR: δ 25.60, 26.13, 26.33,
32.30, 36.17 (CH2), 43.70 (br, BCH), 54.39 (9-C, 10-C), 124.80
(1-C), 125.56 (2-C), 141.02 (Cq). 11B NMR: δ 29.3 (h1/2 ) 1000
Hz).
X-r a y Str u ctu r e Deter m in a tion s for 1a , 3a , 5a , a n d 6b.
Data were collected on a Stoe-Siemens diffractometer with
monochromated Mo KR radiation (λ ) 71.073 pm). The
temperatures of the measurements are listed in Table 3. The
structures were solved by direct methods using SHELXS-90.41
All non-hydrogen atoms were refined anisotropically. For the
hydrogen atoms the riding model was used. The structures
were refined against F2 with a weighting scheme of w-1
)
2
σ2(Fo2) + (g1P)2 + g2P, with P ) (Fo + 2Fc2)/3 using SHELXL-
93.42 The R values are defined as R1 ) ∑||Fo| - |Fc||/∑|Fo| and
2
4 0.5
wR2 ) [∑w(Fo - Fc2)2/∑wFo
] . Figures 1 -5 (hydrogen
atoms omitted) show 50% probability displacement ellipsoids.
Crystal data and structure refinement details are listed in
Table 5.
1,3-Bis(d i-i-bu tyla m in o)-(9,10-d ih yd r op h en a n th r en e-
9,10-d iyl)-1,3-d ibor oxa n e (7). Yellowish, viscous liquid (bp
180 °C (0.001 Torr)). Anal. Calcd for C30H46B2N2O2 (472.33):
C, 76.29; H, 9.82; N, 5.93. Found: C, 75.89; H, 9.85; N, 5.86.
MS: EI m/ e (rel intensity) 472 (5) [M+], 178 (100); FI 472
(41) Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, 46, 467.
(42) Sheldrick, G. M. SHELXL-93, program for crystal structure
refinement, University of Go¨ttingen, 1993.

2284 Organometallics, Vol. 16, No. 11, 1997
Maringgele
Su m m a r y. Bis(dialkylamino)dihalogenodiboroxanes, 1, are
obtained together with the corresponding tris(dialkylamino)-
boroxines, depending upon the steric requirement of the
N-alkyl substituents. Upon dehalogenation of 1 with Na/K
alloy, tetrakis(dialkylamino)-1,4-dioxa-2,3,5,6-tetraborinanes
3 were formed, and in the case of the sterically most demand-
ing di-s-butylamino substituents, the corresponding 1-oxa-2,3-
diborirane, 4c, was isolated. Dehalogenation of 1 in the
presence of naphthalene, anthracene, or phenanthrene re-
sulted in the 1,2-(dihydronaphthalene-1,2-diyl), (9,10-dihy-
droanthrancene-9,10-diyl)-, or (9,10-dihydrophenanthrene-
9,10-diyl)-1,3-diboroxane derivatives, respectively.
Ack n ow led gm en t. Support of this work by the
Fonds der Chemischen Industrie is gratefully acknowl-
edged.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data, complete fractional coordinates and U values, bond
lengths and angles, and anisotropic displacement parameters
and fully labeled figures of 50% anisotropic displacement
parameters of the structures 1a , 3a , 5a , and 6b (28 pages).
Ordering information is given on any current masthead page.
OM960933X