Stabilization of Monomeric Dichlorogermylene.

which (3) is likewise formed in high yields as end product,
for, in these cases CH- and C-C2H5 groups instead of
a C-CH3 group would be incorporated into the five-membered ring. The intermediates (26) and (2c) differ from
( 2 u ) only in that they contain AI(CH&CI and
AffC3H7)2C1instead of A1(C,H s)zC1.
On the basis of these findings the formation of the fivemembered ring can be explained only on the assumption
that a butyne molecule is halved at the C r C bondlsl,
each of the two halves then reacting with a further two
molecules of butyne with ring closure. Further, conclusive
evidence for this route was provided by the analogous
reaction of 3-hexyne, which also undergoes cleavage at
the C E C bond with formation of the chromium(r1)complex
(4a), which can be reduced to hexaethylbenzene(pentaethylcyclopentadienyl)chromium(I) ( 5 ) . ( 5 ) was characterized by elemental analysis, its mass spectrum (m/e= 503),
and its paramagnetism (pefr=1.73 pB).
To our knowledge this is the first case of a high-yield
scission of a C-C bond. We refer to this phenomenon
as
With the old method in which Cr02C12 is employed, (3)
is obtained in yields of, at most, 5-10%, whereas with
crystalline CrC13 the yields are > 70 %. We presume that
the ordered surface of the CrCI3, or of the initial reduction
product with Al(C2Hs)3, plays a decisive role here and
that the dichotomy possibly followsformation of a complex
of one butyne molecule with two chromium atoms situated
a certain distance apart from each other on the surface.
Evidence for this is provided by the fact that deep blue,
crystalline pentamethylcyclopentadienylchromium chloride (6) can be isolated as a minor product on working
in this sense, (6) reacts with Al(CZH5)3and 2-butyne
to give ( 2 a ) and (3). The paramagnetic complex (6)i'I
is soluble both in hydrocarbons and in water and can
be salted out of the aqueous phase by NaCI. (6) can
also be formed from (3) and chlorine.
A further by-product which we have obtained on working
up the reaction mixture (cf. reaction scheme) is, according
to the mass spectrum, a tetrameric pentamethylcyclopentadienylchromium oxide (7) ([C,,H,,OCr],,
m/e=182),
whose structure is possibly similar to that of a previously
reported cyclopentadienylchromium oxide'81. In this
connection it is also of interest to note that treatment
of (3) with H 2 0 2leads to cleavage of hexamethylbenzene
and conversion into a dimeric pentamethylcyclopentadienylchromium dioxide ( 8 ) ([CloHl s02Cr]2, m/e=438).
Received: May 21, 1973 [Z 925 IE]
German version: Angew. Chem. 85,1052 (1973)
Publication delayed at authors' request
[I] G . Wilke and M. Kroner, Angew. Chem. 71, 574 (1959).
[2] W Hafner and E . 0. Fischer, US-Pat. 2953586 (1960)
[3] We thank Dr. H . Hoberg for the magnetic measurements.
[4] M . Mzchman and H . H . Zriss,J. Organometal. Chem. 25, 161 (1970).
[5] This possibility was first discussed in this connection by R . KBsrer.
[6] Dichotomy from the Greek GyoropB = halving
[7] (6) shows unusual magnetic properties. The susceptibility Increases
only slightly with decreasing temperature (293°K; 4.2p1,, 143°K: 3.1 pa).
[ 8 ] E. 0. Fischer, K . Ulm, and ff. P. Frrrz, Chem. Ber. 93, 2167 (1960);
G . Wilkinson, F . A . Cotton, and J . M. Birminyhnm. J. Inorg Nuci. Chem.
2, 295 (1956).
Stabilization of Monomeric Dichlorogermylene
By Peter Jurzi, Hans Joachim Hoffmann, David John Brauer,
and Carl Kriiger"]
t
j.
1
In Group IVB, the stability of divalent compounds
increases from carbon to lead owing to known criteria.
Thus in contrast to dichlorocarbene, dichlorogermylene
is stable under normal conditions; however, except for
a dioxane adduct''], it exists as a polymer of unknown
structure. We now report the stabilization of monomeric
dichlorogermylene by complex formation with aromatic
nitrogen bases.
Whereas organotrichlorogermanes undergo a reaction analogous to transsilylation'*] with 1,3-benzothiazol-2-yltrimethylsilane ( 1), forming di- and tribenzothiazol-2-yfgermanesi31, we observed uniform and quantitative addition
to the C=N bond on reaction of trichlorogermane with
( I ), affording 2,3-dihydro-2-trimethylsilyl-2-trichlorogermylbenzothiazole (2): 'H-NMR (in CDC13, TMS
internal): & - H 14.43 ppm, variable (1); & , r o m a r , c ~ 7.678.94 ppm, M (4);8SilCH313
0.85 ppm (9). IR (in Nujol): v ~ =3200, 6Si(CHa,,
= 1255, v
~=320,
~ 270
~ cm, '. ~M. W.:
calc. 387.27, exp. (in C,H,) 350.
(2) decomposes exothermally at 91 "C13alwith liberation
of trimethylchlorosilane; from the residue we obtained
the dichlorogermylene-benzothiazoleadduct (3) in 75 /o'
[*] Priv.-Doz. Dr. P. Jutzi and DipLChem. H. J. Hoffmann
up the reaction mixture; that is, formation of the five-membered ring takes place first and only after further reduction
is the six-membered ring formed and complexed. Thus,
1002
Institut fiir Anorganische Chemie der Universitat
87 Wiirzburg, Am Hubland (Germany)
Dr. C. Kruger and Dr. D. J. Brauer
Max-Planck-Institut fur Kohlenforschung
433 Mulheim-Ruhr, Lembkestrasse 5 (Germany)
Angew Chem internat Edit.
I
Vol 12 (1973) / No. 12
~
yield after recrystallization from benzene as colorless crystals of m.p. 131 C.
was established by the heavy atom method ; least-squares
refinement of the atomic parameters (isotropic for H, anisotropic for all other atoms) led to an R value of 0.037.
The bond anglesat the threefold coordinated germanium are
about 90°, the distance G e 4 I and the angle C l - G e 4 I
resemble those in C l , G e " . d i ~ x a n e ~and
~ ~ CI,Ge'"[nC5H5Fe(C0)2]2[61;
however, these values differ consider-
cH3
c11
( 3 ) proves surprisingly resistant to hydrolysis and to be
thermally stable, dissolving readily in anhydrous ethanol,
ethylene bromide, and chloroform, and moderately in benzene. Molecular-weight determinations (in (CH2)2Br2)confirm the monomeric structure (3); the monomeric molecular ion with the expected isotopic distribution also occurs
as the uppermost peak in the mass spectrum.
The 'H-NMR spectrum (in CDC13, TMS internal) of (3)
exhibits signals typical of the benzothiazole skeleton : a
multiplet at 7.67-8.68 ppm (4) and a singlet for C2-H
at 10.17 ppm (1). The IR spectrum (in Nujol, [email protected] ') is almost superimposable upon that of free benzothiazole, the additional bands at 350 and 295 cm-'
being assigned to Ge-CI stretching vibrations.
In the reaction oftrichlorogermane with N-methylbenzimidazol-2-yl-trimethylsilane ( 4 ) we have not isolated the
initial addition
since in this case the loss of
trimethylchlorosilane occurs already at room temperature,
with immediate formation of dichlorogermylene-N-methylbenzimidazole adduct ( 5 ) : m. p. I72'C (dec.); 'H-NMR
(in CDC13, TMS internal): lo ma tic^ 7.43-8.10 ppm (4);
& - H 9.05 ppm (I), &H,
4.09 ppm (3); M.W. 276 (mass
spectrum).
Synthesis of GeClz adducts via the non-silylated heterocycles (6) is impossible since no addition to the C=N
bond takes place but instead protonation to give the thermally stable immonium salts (7).
ji92111
Fig. I . Perspective representation of 3-dichlorogermyIene-l,3-benzothiazole ( 3 ) . Standard deviations for bond lengths (A): 0.001 Ge-CI, 0.002
Ge-N, 0.003 S-C, 0.005 C-N, C-C; for angles ( ): 0.1 CI-Ge-CI,
N-Ge-CI,
all other angles 0.2.
ably from those in Ge'"CI4 (2.08(2)A, 109.5")['1. The G e C I
distances and Cl-Ge-CI
angles in polychlorinated Ge
compounds thus reflect not only the oxidation state of
the germanium, but also the electronegativity of the coordinated atoms. This finding is in accord with both electronpair repulsion theory[s' and hybridization theoryl'l.
The measured Ge"-N
distance is 0.13 A greater than
the sum of the covalent
but 0.lOA smaller than
'1. The G e atom
the GeIV-N distance in C14Ge.N(CH3)3[1
in (3) IiesO.168A above the plane ofthe planar (k0.016A)
benzothiazole skeleton, which bisects tht angle CI-Ge--Cl.
The bond length S 4 7 is 0.061(4) A shorter than the
corresponding bond length in 2-methylaminobenzothiazole[' 21. This finding suggests n-electron delocalization in
the five-membered ring, probably with participation of
sulfur d orbitals. Adduct formation at the nitrogen does
not significantly modify the benzothiazole skeleton. Two
short intermolecular distances, between germanium and
sulfur (3.61 8(1) A) and germanium and chlorine (3.499(I ) A),
could be indicative of weak bonding interaction^"^!
Received: July 27, 1973 [Z 927 I€]
German version : Angew. Chem. 85, 1116 (1973)
X = S, NCH,
The structure of (3) (cell data: a= 15.276(6), b=8.108(3),
c=8.260(3)A; /3= 109.52(3)"; space group P2,/c; 2 = 4 ;
dealc.= 1.92 g cm- 3 , was determined by three-dimensional
X-ray structure analysis.
From the 4227 reflections recorded by a computer-controlled diffractometer (Mo-Kr, h=0.71069 A), 21 12 structure amplitudes corrected for absorption effects
(p=40.5cm- ') were derived, 193 measurements being
regarded as unobserved ( I > 2 0 ( I ) ) .The molecular structure
A n y n v . Chrm. infernat. Edit. / Vol. 12 (1973) 1 No. 12
[ I ] S. P. Ko~emrkoc, Y J . Shiryarc. and 0. M . N r f i d o ~ ,Izv. Akad.
Nauk SSSR, Ser. Khim. 1966, 584.
[2] P. Jufzi and H.J . Hoffmann, J. Organometal. Chem. 40, C61 (1972).
[3] P. Jufzi and H. J . Hofmann, unpublished.
[3a] DuPont Thermal Analyzer 990.
[4] W Sakriss, Diplomarbeit. Universitat Wurzburg 1973.
[S] K 1. Kulishou, N . C . Bokii, 0. M . Nefedov, S. P . Kolesnikor, and
8. M . Mutter, Zh. Strukt. Khim. I f , 71 (1970).
[ 6 ] M . A. Bush and P . Woodward, J. Chem. SOC.A 1967, 1833.
[7] L. Pouling and L. 0. Brockwoy, J. Amer. Chem. SOC.57, 2684 (1935).
[XI R . J . Gdlespie, Angew. Chem. 79, 885 (1967): Angew. Chem. internat.
Edit. 6 , XI9 (1973).
[9] H . A. Bent, Chem. Rev 61, 275 (1961).
[lo] L. Pauling: The Nature of the Chemical bond^ 3rd Edit Cornell
University Press, Ithaca. N. Y. 1960.
[ I I ] M . S . B i h n and M . Wehstcr, J. C. S . Dalton lY72, 722.
[ 121 M . Frhlmann, Acta Crystallogr. B26, 1736 (1970).
(131 N . W Alcock, Advan. Inorg. Chem. Radiochem. I S . I (1972).
1003