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Isolation of Halohydroborates of Type [B10H10 nXn]2.

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high vacuum at -40°C and then any unconsumed ( 1 ) at
room temperature. The brown residue crystallizes from diethyl
ether/methylene chloride (2 : 1, - 35°C); yield 41 0 mg (27 %)
of (2).
b) N-Alkyl-N-nitrosourea variant : A mixture of ( 1 ) (1.80 g,
10mmol) and N-rnethyl-['"l or N-ethyl-N-nitro~ourea[~~]
(1 5 mmol, 1.55 and 1.76 g resp.) in benzene (40 ml) is heated
under reflux for 8 h . The solution is evaporated down in
a high vacuum and the residue chromatographed (20 x 3 cni
column; + 15'C) with benzene on silica gel (0.063-0.200mm,
Act. 11-111). Recrystallization (diethyl ether/methylene chloride 2: 1 ; -35°C) of the substance obtained from the brown
zone yields 918 g (61 %) of analytically pure (2).
I
I
fast
p a r a m agne ti c
dlaniagnetic
vN0: 1 5 4 3 c m - ' ;
iN0:
vco:
18 l'fcin - ' ( K B r )
3585,
152 j c m - ' ( K R r )
N-Methyl- and N-ethyl-N-nitrosourea react with ( I ) in
boiling benzene to give exclusively the partially nitrosylated
product (2), even when used in twofold excess. This large
difference in reactivity in comparison to NO underlines the
preparative importance of these two nitrosourea derivatives
as very mild nitrosylating reagents for metal carbonyls. They
are readily accessible and thermally relatively stable (m.p./dec
> 100"C). This also applies for N-nitroso-p-toluenesulfonamide. which is employed for a similar purpose in complex
chemistry; its use in the case described here, however, leads
only to mixtures of the diffcultly separable complexes (2)
and ( 3 ) .
The structure of (2), confirmed by an X-ray structure analysis to be a dinuclear complex containing a Co-Co single
bond[31,is consistent with its paramagnetism (1.86 pBi2]),which
we were also able to detect ESR spectroscopically. The 1 5-line
system (ko=47.4, aN< 14 Oe; g-factor 2.0539) evidences uniform charge distribution over both C o nuclei ( I = 7/2); were
the unpaired electron to reside preferentially on the bridge
ligand, as in the p-peroxobis(pentamminecoba1t) ion[41, ko
would be much smaller.
Received: November 30. 1976 [Z 618 IE]
revised: December 3. 1976
German tersion: Angew. Chem. 89. 186 11977)
CAS Registry numbers:
( I ) . 12078-23-8: (2), 58071-48-0; ( 3 ) . 51862-20.5; N-inethyl-N-nitrosotirea,
684-93-5. N-eihyl-N-nitrosourea, 759-73-9
H . Brimnn.. J. Organomet. Chem. I ? . 517 (1968).
( 2 ) was first obtained by photoinduced reaction of (31 urith ( 1 ) J .
,Vii/ier. S . Schniitr. J. Organornet. Chem. 97, C 54 (1975).
(2) crystallizes monoclinically; space group P2,/c, 2 = 2 . For a detailed
description of the structure of (2). see I . Berrwl. J. Korh, M . G. Reisriw,
U! A. H ~ r r r n o w rJ.~ .Organomet. Chem., in press.
I . Berrtul, E . 4. I! Ebs~rorrh.J. A . Wed, Proc. Chem. Soc. London
JYSY, 57: J. A . Weil, J. K. Kirmaird. J. Phys. Chem. 71, 3341 11967).
All work carried out under nitrogen and i n thc absence of moisturc.
Prepared according to M. D Ruiisdi, R. -4. Genetfi. J. Org. Chem.
35, 3888 (1970).
a) O r p n i k u m . 12th edit., VEB Dcutscher Verlag dcr Wissenschaften
Berlin 1973, p. 584: b) Reagent from Fluka-Feinchemikalien. -The acetic
acid added for stabilization is removed by urashing with water. The
compound can be stored for several months at 35 "C.
Isolation of Halohydroborates of Type
[B I OHI o - n X n 1 2 By Klaus-Georg Biihrens and Wilhelm Preetz[*l
Electrophilic substitution reactions on hydrodecaborate
ions ( 1 ) with chlorine, bromine, or iodine in aqueous or
alcoholic solution lead to the corresponding halohydroborates
(2)"'.
X
Fig. I. ORTEP diagram of (2). The Co2(NO)(CO)fragment i s coplanar
(max. deviation from the plane +0.4pm). Bond lengths: Co-Co 237.0pm
(single bond). Co-Co = Co-NO 182.9 pm; angle CoNCo ( = XCoCCo)
80.7".
:
a) Nitrogen monoxide variant: A slow stream (0.5 mm capillary) of dry N O gas is passed through a magnetically stirred
(1.8Og, 10mmol) in n-pentane (100ml) at
solution of
- 120°C. After 10 minutes, the solvent is first removed under
Anyew. Chem. Inr Ed Engl. 16 (1977) N o . 3
=
C1, B r . I; n = 1 - 9 , l O
Only the terminal members (n = 10)of the three homologous
series (2) have as yet been confirmed, while it was not ruled
out for the few intermediates isolated-e. g. B10H2Clf-,
BIOH3Br:-, BloH81:-i'1-that
mixtures ofseveral of the very
similar species had actually been obtained.
By means of electrophoresis['] we have now detected all
the substituted species (2), of which the compounds listed
in Table 1 were isolated in pure form. They were characterized
by elemental analysis and vibrational spectra of the sparingly
soluble tetramethylammonium salts.
[*] Prof. Dr. W. Preetz, Dr. K.-G. Biihrens
Institut fur Anorganische Chemie der Universitiit
Olshausenstrasse 40--60, D-2300 Kiel (Germany]
173
Table I . Characteristic IR frequencies [cmates.
'1 of the isolated halohydrobor-
[ ( C H ~ ) ~ N ] ~ B I O H2535
~ ~ Ish. 2515 sh, 2495 VS, 1125 sh. 1105 S, 1010
w,880 w, 820 w,800 w
[ ( C H ~ ~ N I ~ B I O H 2520
~ C ~ vs,
Z 1180 vw, 1070 m, 1020 m, 870 m, 835
m, 805 s, 725 m
[ ( C H J ) ~ N ] Z B I O H ~ C 2540
I ~ sh, 2505 vs, 1175 w, 1075 m, 1030 m. 885
m,830 s. 820 s, 735 s
[ ( C H J ) ~ N ] Z B ~ ~ H ~2530
C I ~VS, 2510 VS, 2485 Sh, 1100 S. 1075 sh, 1035
s. 895 m, 875 m, 845 s, 755 s
[(CHI)IN]LBIOHSCIS 2560 sh, 2540 VS, 1140 sh, 1095 S, 1035 S, 860 S,
br, 780 sh, 760 s
[ ( C H ~ ) ~ N ] Z B I O H ~2555
C ~ s,
~ I150 sh, 1095 s, 1040 s, 875 s, br, 780 m,
760 sh
[(CH3)4N]2BIOH9Br
2515 sh, 2505 vs, 2465 vs, 1125 sh, 1105 m, 1010
w, 880 w, 840 sh, 820 ni, 790 m
[(CH3)4N]2BI0HsBr2 2520 sh, 2495 vs, 1175 vw, 1100 s, 1075 m, 1035
w, 875 w, 850 sh, 830 m, 790 s
[(CHd4N]2BI0H7Br3 2520 sh, 2510 sh, 2495 vs, 1100 s, 1070 m, 1020
m, 870 m, 850 m, 830 sh, 800 s
[(CH3)4N]2B10H6Br4 2525 s, 1120 w, br, 1070 m, I020 m, 870 w, 820
m, 810 m, 795 m
[ ( C H ~ ) J N ] Z B I O H S B2525
~ ~ s, 1130 sh, I l l 0 m, 1070 w, 1010 rn, 870 sh,
825 s, 810 sh, 805 sh
[ ( C H S ) A N ] Z B ~ O H ~ 2530
B ~ ~ s, 1150 sh, 1110 m, 1005 m, 870 w. 810 s
[ ( C H ~ ) ~ N ] Z B I O H ~ I2510 s, 2485 vs, 2475 sh, 1100 w, I010 m, 840 w,
810 m, 785 m, 770 m, 720 m
[ ( C H ~ ) ~ N ] Z B I O H S I Z2510 sh, 2490 VS, 2470 sh, I175 W, 1100 S, 1070
m, 875 m, 830 w, 780 s, 765 sh
[ ( C H S ) ~ N ] ~ B I O H ~2545
~ ~ sh, 2530 s, 2495 s, 1030 m, br, 1100 s, 860
m, 802 m, 785 s, 770 s
[ ( C H ~ ) ~ N ] ~ B I O H & 2540 s, 2516 s, 1120 sh. 1115 rn, lo20 w, 860 m,
840 sh, 805 m, 790 in, 725 rn
The rate of reaction decreases along the series CI2> Br2 > 12.
It is very high for the initial reaction steps and diminishes
with increasing degree of halogenation. The solutions invariably contain 3 to 5 successive components, of which those
in the middle are present in the highest concentration. The
maximum shifts systematically towards higher values of n
as the halogenation time increases. The ion mobilities decrease
with increasing degree of halogenation. The difference in mobility therefore becomes progressively smaller and the ions having n > 6 can no longer be completely separated. The pherogram of a mixture of all radioactively labeled chlorohydroborates and the relevant activity profile are shown in Figure 1.
the Raman spectra recorded on saturated acetonitrile solutions. Presumably, several geometrical isomers coexist in the
solutions. The intensity of the BH stretching vibrations steadily
diminishes with increasing halogenation while the center of
gravity of the bands shifts to higher frequencies. The increase
in strength of the BH bond manifested in this shift is paralleled
by an increase in stability of the products.
Procedure:
A current of Nz carrying a very small amount of ClZ or
Br2 is passed through ice-cooled solutions of (NH4)2B10H10
(1.5 g, 0.01 mol) in water (50 ml) (only a few minutes for preparation of species with n < 3, and up to an hour for more highly
halogenated compounds). Iodination is performed by shaking
the aqueous solution with a few ml of CC14 in which iodine
is dissolved until the iodine color disappears, the procedure
being repeated if necessary. After filtering off resinous sideproducts the mixtures (2) are precipitated from the aqueous
solutions as the tetramethylammonium salts which are recrystallized from acetonitrile/water. They are treated with a cation
exchanger to give the more soluble NH: or Na' salts, which
are subjected to high voltage electrophoresis. On spraying
of the pherograms with a dilute acridine hydrochloride solution the separated colorless halohydroborates give yellow
zones which are cut out, collected, and eluted with 0.01 M
NaOH. After concentration the ions (2) can be precipitated
with tetramethylammonium chloride. Recrystallization from
water/alcohol (almost pure alcohol for n = 1, almost pure water
for n=6) gives the colorless finely crystalline salts
[ ( C H ~ ) ~ N ] ~ B ~ OinHyields
~ ~ - between
~ X ~ 20 and 60mg.
Received: December 3, 1976;
supplemented: December 21, 1976 [Z 637 IE]
German version: Angew. Chem. 8Y. 195 (1977)
CAS Registry numbers
(NH14)zBioHio,12008-61-6;[(CH3)4N]2B10H9CIi 61617-71-8:
[(CH3)4N]zBioHsCl2. 51668-03-2;[ ( C H ~ ) ~ N ] ~ B ~ O57594-30-6;
H~CI~,
[(CH~)IN]ZBIOH~CIA,
61 617-72-9;[ ( C H ~ ) ~ N ] ~ B I O H52655-96-6;
~CI~,
[(CH3)4N]2B10H4CI6, 51 745-61-0;[(CH3)4N]ZBIOH9Br,
61617-73-0:
[(CH3)4N]2BloHsBr2,61617-74-1: [(CH3)uN]2B10H7Br3,61617-75-2;
[(CH3)4N]2B10HbBr4,61 61 7-76-3;[(CH3)4N]2B10H5BrS,6161 7-77-4;
[(CH3)aN]2BloH4Brb,61617-78-5;[(CH3)4N]2BioH9Ii 61491-42-7;
[(CHdaN]aBioHsl2,61617-79-6:
[(CH3)4N]zBioH713,61617-80-9:
[(CH~)~N]ZB~O
61H61~7-81-0
I~,
W H . Knoth, H . C. Miller, J . C. Sauer, J . H . Balrhu, Y 7: Chia, E .
L. Muetterties. lnorg. Chem. 3, 159 ( I 964).
[2] W Pwerz, Fortschr. Chem. Forsch. 11. 375 (1969): K -G.Biihrens, W
Preerz, J. Chromatogr., in press.
[I]
-
Direction of migration
4
DDDDDDDD D ~ J
hn10-8
7
6
5
G
3
2
9
0
Fig. 1. a) Pherogram and b ) activity profile of compounds BIoHIO-.CI?
labeled with "CI.
In the vibrational spectra, the BH stretching frequencies
are seen in the 2470-2560 cm- ' region, the skeletal frequencies in the 1ooO-I300 cm-' region, and the B-X stretching
frequencies in the 700-895 cm-' region. In the more extensively halogenated species in particular, characteristic splitting
patterns are observed which are especially pronounced in
174
The Reaction of Olefins with Silane and Carbon Monoxide Catalyzed by C O ~ ( C O ) ~ [ ' ~
By Yoshio Seki, Akihiko Hidaka, Shinji Murai, and Noboru
Sonoda[*]
Hydrosilylation, the catalyzed addition of R3Si-H to an
olefin, is formally analogous to catalytic hydrogenation. The
well-known hydroformylation reaction involves addition of
hydrogen and carbon monoxide to olefins [Reaction (a)].
Addition of a silane and carbon monoxide to olefins, however,
has not been reported apart from in a very complex reaction
described almost a decade ago['].
[*] Y . Seki, A. Hidaka, Prof. Dr. S. Murai ['I, and Prof. Dr. N. Sonoda
Department of Petroleum Chemistry, Faculty of Engineering, Osaka
University
Suita, Osaka 565 (Japan)
['I Author to whom correspondence should be addressed
Angew. Chem. I n t . Ed. Engl. 16 ( 1 9 7 7 ) N o . 3
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