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Diboron Polyboron and Metal-Boron Compounds.

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Diboron, Polyboron, and Metal-Boron Compounds
Diboron compounds BzX4 are readily accessible by dehalogenation of boron chlorides XzBCI provided at least
one of the ligands X in XzBCl is a dimethylamino group:
b) Acid-catalysed cyclization [2] of P-alkoxydiazoketones
yields 2-methyl- (5
4-methyl- (41
and 5-methyl- (30 %)
tetrahydrofuran-3-ones.
c) Base-catalyzed cyclization 131 of P-oxa-adipoyl chloride
leads via the di ketene to 3-keto-4(2)-ethoxycarbonyltetrahydrofuran, which on hydrolysis and decarboxylation gives
( I ) in 45 % yield.
+ 2 KCl (a)
2. S p i r a n e s
All diboron compounds tend to disproportionate as follows:
Monospir0[5,5]undecane (2) dispiro[5,2,5,2]hexadecane (3),
m.p. 84 "C and trispiro[5,2,2,5,2,2]heneicosane (4), m.p.
158 "C, can be prepared in reasonable yields by reduction of
H. Niith, Munich (Germany)
2 X [(HjC)zNIBCl+ 2 K + X[(HjC)zN]B--B[N(CH,)21X
X = N(CH&z, CH3, CzHs, GH7, C ~ H SOR,
, 01PR2
BzX4 + BX3
+ 1 (BX),
'x),
'x),
(b)
Stability increases along the series X = CI, OR, NRz. Disproportionation of mixed diboron compounds proceeds in a
121
(3)
somewhat more complex manner than that according to (b),
but here, too, boron(ll1) and polyboron compounds are
always formed. The increase in stability in the series B2Cl4,
BzH"(CH3)zIdMOCH ~)~,BzRz~N(CH~)Z~Z,BZRIN(CH~)Z~~,
BzC12 [N(CH3)&. Bz[N(CH3)2]4 demonstrates the stabilizing
(4)
influence of the N(CH& group, which is of both electronic
and steric nature. A mechanism is proposed for the course of
the ketones obtained from a double Michael condensation bethe disproportionation which leads to polyboron compounds
tween divinyl ketone and 1,3-cyclohexadiones [4], or by a
via boron compounds with chain-structures.
dialkylation reaction of cyclohexanones [5]. The protons of
In parallel with thermal stability, there is also a decrease in
the outer- and inner rings in (3) and (4) show r-values of
reactivity of the B -B bond. Bz[N(CH3)2]4 cannot be hydro8.65 and 8.75 respectively.
genated even at 20O0C/2O0 atm while BzCIZ[N(CH~)Z]~
is
hydrogenated to [HBClN(CH3)& already at 100 OC/50 atm.
3. D i t h i e n y l s
Reaction ofHCl withBz[N (CH3)2]4 leads toBzC14.2 HN(CH3)z
The dipole moments of 2,2'-dithienyl (5), 2,3'-dithienyl (6),
via BzCl[N(CH3)2]3 and B~CIZ[N(CH~)Z]Z.
The dichloroand 3,3'-dithienyl(7) were found to be 0.11,l .Ol, and 0.75 D,
derivative can also be prepared from 1 mole of BCl3 and
respectively, in benzene solution.
1 mole of Bz[N(CH3)2]4. If the stabilizing influence of the
N(CH3)z groups is absent in substitution reactions, disproportionation occurs along with substitution. Thus, when
HCI, BF3, and ROH Interact with BzR~[N(CH~)&,RBXz
and (BR) are obtained, but not the diboron compounds
BzRzX2 (X = CI, F, or OR). The decomposition of the
diboron compounds offers the best method available at
present for the preparation of polyboron compounds.
The stabilizing effect of the N(CH& group makes it possible
to synthetize dimethylaminoboron compounds with chain
It appears that in (5) and (7), the rings are preferentially a t
structures, i.e. the homologous series Bn[N(CH3)2In+2; so
nearly 90 to one another [6], while in (6), coplanarity is the
far, members up to n = 6 have been isolated.
predominant conformation.
Attempts to produce boron-lithium, boron-magnesium, and
[GDCh-Ortsverband Frankfurt/Main (Germany)
boron-mercury compounds have proved unsuccessful. BoronFebruary 21st, 19631
metal bonds have, however, resulted from reaction of
[VB 693/80 IE]
sodium carbonylometallates with boron chlorides.
[Anorganisch-chemisches Institut, Universitat Gottingen
(Germany), February 18th, 19631
WB 691/81 IE]
Photochemical Reactions with Transition Metal
Carbonyls
W . Slrohmeier, Wurzburg (Germany)
Tetrahydrofuran-3-one, Spiranes, and Bithienyls
H. Wynberg, Groningen (Holland)
1. T e t r a h y d r o f u r a n - 3 - o n e s
Three synthetic routes leading to compounds of this type have
been developed:
a) Greatly improved oxidation [l] with chromic acid or
pyridine/chromic oxide of the corresponding 2-, 4- or 5 substituted 3-hydroxytetrahydrofurans furnishes ( I ) in
yields of up to 70 %.
111 Yu. K . Yur'ev, E . M. Lukina, and I . K. Korobitsyna, Zhur.
obsh. Khim. 24, 1238 (1954); Chem. Abstr. 49, 12430 (1955);H.
Wynberg, J. Amer. chern. Soc. 80, 364 (1958).
270
If a solution of a metal carbonyl or a metal carbonyl derivative is irradiated with ultraviolet light in the presence of an
electron donor D, carbon monoxide is split off photochemically according to equation (a)
YM(CO),
+ :D + hv + YM(CO),-lD
f CO
(a)
and the donor is substituted in the vacant orbital on the
metal carbonyl. Suitable electron donors are, "n"-donors
[ 2 ] H. E. Sheffer and J . A . Moore, S. org. Chemistry 28, 129
(1963).
[3] J . C. Sauer, J. Amer. chern. SOC.69, 2448 (1947).
141 H . A . P . de Jongh and H . Wynberg, Recueil Trav. chim. PaysBas 82,202 (1963).
151 M . Mousseron, R . Jacquier, and H . Cristol, Bull. SOC. chim.
France 1957,346.
[6] A . Almenninger, D . Basfiansen, and P . SvendsGs, Acta chem.
scand. 12, 1671 (1958).
Angcw. Chem. intrrnat. Edit.
I
Vol. 2 (1963) I No. 5
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diboron, compounds, metali, polyboron, boron
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