Octagallane (tBu3Si)6Ga8 and its reduction to (tBu3Si)6Ga82- - On the existence of isomeric gallium clusters

Article abstract of DOI:10.1002/1099-0682(200203)2002:4<929::AID-EJIC929>3.0.CO;2-6

Thermolysis of the trigallanyl radical R*₄Ga₃ in heptane at 60 °C leads to the dark blue octagallane R*₆Ga₈ (R* = supersilyl SitBu₃), as well as the digallanyl radical R*₃Ga₂ and the tetrahedro-tetragallane R*₄Ga₄. In addition, supersilyl radicals R* are formed which stabilize themselves either by dimerization or by addition of hydrogen atoms. R*₆Ga₈ can be reduced in THF with NaC₁₀H₈ to the dark-red octagallanediide Na₂Ga₈R*₆·2THF. According to an X-ray structure analysis of R*₆Ga₈ and R*₆Ga₈^2- one finds that the Ga atoms of four R*Ga moieties, together with two naked Ga atoms, occupy the corners of a distorted octahedron; the naked Ga atoms themselves are located, along with Ga atoms of two further R*Ga moieties, at the corners of a distorted square. The reduction of R*₆Ga₈ leads only to a negligible shortening of the Ga-Ga distances from 2.64 to 2.61 A (mean values) in R*₆Ga₈^2-. Both the octagallanes possess Ga₈ frameworks previously unknown for group 13 clusters. They are isomeric to the recently described Ga₈ framework of the octagallane Tsi₆Ga₈ [Tsi = trisyl C(SiMe₃)3]. Hence, not only boron but also the heavier group 13 atoms form isomeric clusters.

Full text of DOI:10.1002/1099-0682(200203)2002:4<929::AID-EJIC929>3.0.CO;2-6

FULL PAPER
2؊
Octagallane (tBu3Si)6Ga8 and Its Reduction to (tBu3Si)6Ga8
On the Existence of Isomeric Gallium Clusters[‡]
؊
Nils Wiberg,*[a] Thomas Blank,[a] Heinrich Nöth,[a][‡‡] Max Suter,[a][‡‡] and
Markus Warchhold[a][‡‡]
Keywords: Clusters / Gallium / Isomers / Silicon
·
Thermolysis of the trigallanyl radical R*4Ga3 in heptane at
occupy the corners of a distorted octahedron; the ‘‘naked’’ Ga
atoms themselves are located, along with Ga atoms of two
60 °C leads to the dark blue octagallane R*6Ga8 (R* = su-
persilyl SitBu3), as well as the digallanyl radical R*3Ga2 and further R*Ga moieties, at the corners of a distorted square.
·
the tetrahedro-tetragallane R*4Ga4. In addition, supersilyl
radicals R*· are formed which stabilize themselves either by of the Ga−Ga distances from 2.64 to 2.61 A (mean values)
dimerization or by addition of hydrogen atoms. R*6Ga8 can
in R*6Ga82−. Both the octagallanes possess Ga8 frameworks
The reduction of R*6Ga8 leads only to a negligible shortening
˚
be reduced in THF with NaC10H8 to the dark-red octagal- previously unknown for group 13 clusters. They are isomeric
lanediide Na2Ga8R*6·2THF. According to an X-ray structure to the recently described Ga8 framework of the octagallane
analysis of R*6Ga8 and R*6Ga82− one finds that the Ga atoms
of four R*Ga moieties, together with two ‘‘naked’’ Ga atoms,
Tsi6Ga8 [Tsi = trisyl C(SiMe3)3]. Hence, not only boron but
also the heavier group 13 atoms form isomeric clusters.
Introduction
Cluster compounds RmEn of the heavier group 13 metals
Al, Ga, In, Tl — unlike those of B — became accessible
only recently when it was realized that the tendency of
RmEn to disproportionate into R3E and E (or R2 and E)
can be stopped by employing bulky substituents such as
trisyl (Tsi) [C(SiMe3)3], hypersilyl (Hsi) [Si(SiMe3)3] or su-
persilyl (R*) [Si(CMe3)3]. In fact, numerous clusters of
Ga — the subject of this publication — have been isolated
within the last few years (for more than 30 gallium cluster
compounds see ref.[1]).
Schnöckel and co-workers[2] recently reported the pre-
paration of hexatrisyloctagallane Tsi6Ga8 (1) with a frame-
work of two tetrahedro-tetragallanyl moieties connected by
a GaϪGa bond (see Scheme 1). We now report the isolation
of hexasupersilyloctagallane R*6Ga8 (3) as well as its reduc-
tion product disodium hexasupersilyloctagallanediide-tetra-
hydrofuran(1/2) Na2Ga8R*6·2THF (4), the Ga8 frameworks
of which are isomeric with the Ga8 cluster of Tsi6Ga8
(Scheme 1). It is worth mentioning here that the In8 frame-
work of hexasupersilyloctaindane R*6In8 (2; Scheme 1), re-
ported some years ago by us,[3] has a structure different to
the structures of Tsi6Ga8 and R*6Ga8.
Scheme 1. Compounds with isomeric group 13 E8 cluster frame-
works [Tsi ϭ C(SiMe3)3, R* ϭ SitBu3]
Results and Discussion
Syntheses of R*6Ga8 (3) and Na2Ga8R*6·2THF (4)
·
The dark green radical R*4Ga3 (5), which may be syn-
thesized, via isolable intermediates, from gallium trichloride
GaCl3, supersilyl sodium NaR*, and supersilyl bromide R*
Br,[4] slowly decomposes in heptane at 40 °C with formation
of the dark blue radical R*3Ga2 (6) and the dark violet
tetrahedro-tetragallane R*4Ga4 (7) [see Scheme 2, Equation
[‡]
Compounds of Silicon and Homologues, 152; Compounds of
Boron and Homologues, 19. Ϫ Parts 151 and 18: Ref.[7]
[‡‡]
X-ray structure analyses
·
[a]
Department Chemie der Universität München,
Butenandtstraße 5Ϫ13 (Haus D), 81377 München, Germany
Eur. J. Inorg. Chem. 2002, 929Ϫ934
WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434Ϫ1948/02/0404Ϫ0929 $ 17.50ϩ.50/0
929

N. Wiberg, T. Blank, H. Nöth, M. Suter, M. Warchhold
FULL PAPER
(a); for the structures see Scheme 3].[4] The radical 6 trans- intermediate in the formation of R*8In12 — has been ob-
forms quantitatively at 100 °C in heptane into the tetra- served by NMR spectroscopy[9].) In addition, a cluster
hedrane 7 [Scheme 2, Equation (c)] which decomposes as a formed from two equivalents of 12 with In/Dmp instead of
solid at 322 °C and in solution at 140 °C to metallic gallium Ga/R* has been synthesized[10] (Dmp ϭ 2,6-Mes*2C6H3
[Scheme 2, Equation (e)].[5] The supersilyl radicals R*· ob- with Mes* ϭ 2,4,6-tBu3C6H2). The preparation and isola-
tained in reactions (c) and (e) dimerize to give superdisilane tion of hexagallane 13 is the next challenge for group 13
molecules R*2, which at higher temperatures transform via cluster chemists.
R*· into supersilane R*H.[6]
Scheme 2. Decomposition of 5 (the produced supersilyl radical R*
stabilizes with formation of R*2 and/or R*H; R* ϭ SitBu3)
The thermolysis of 5 in addition leads to the octagallane
R*6Ga8 (3) [Scheme 2, Equation (a); maximum yields at
about 60 °C], which itself decomposes in benzene at 100 °C
to give the tetrahedrane 7 (main product) as well as uniden-
tified cluster compounds RmGan [Scheme 2, Equation (d)].
The octagallane 3 can be reduced in THF with NaC10H8 to
give the octagallanediide Na2Ga8R*6·2THF (4) [Scheme 2,
Equation (b)]. Reduction of the tetragallane 7 in THF with
sodium occurs analogously to produce the tetragallanediide
Na2Ga4R*4·2THF.[7]
To date our insight into the pathways of the formation
and thermolysis of 3 is still incomplete. It is possible that
compounds 8Ϫ13, which are shown in Scheme 3 along with
the isolated products 3Ϫ7, may play the role of interme-
diates (cf. ref.[4] for formation of 3, and the following for
Scheme 3. Isolated and postulated products of the thermolysis of
5 as well as the reduction product 4 of 3 (R* ϭ SitBu3)
thermolysis of 3). Radical 5 can react with cleavage of
GaϪGa bonds to form 6 and 9, as well as 8 and 10, and
with cleavage of a GaϪSi bond to form 11 and R*·; radical
Characterization and Structures of R*6Ga8 (3) and
Na2Ga8R*6·2THF (4)
8, after dimerization and R* elimination, transforms into
isolable 6 (cf.[4]), and radical 6, after elimination of R*, into
non-isolable 10. The formed gallylene 9 and the digallene
Hexasupersilyloctagallane (3) crystallizes from benzene
10 tetramerize and dimerize, respectively, to give isolable 7. as water- and air-sensitive dark blue prisms (monoclinic,
It is also possible that the cyclotrigallane 11 may eliminate space group P21/c) which are thermolabile at elevated tem-
R* and then dimerize with formation of the hitherto non- peratures. Disodium hexasupersilyloctagallanediide-tetra-
isolated hexagallane 13 which, on adding 10, might form hydrofuran(1/2) (4) crystallizes from benzene as extremely
the isolable octagallane 3. This compound decomposes on water- and air-sensitive dark red prisms (triclinic, space
¯
gentle heating to give the isolable tetrahedrane 7 and the group P1).
non-isolable tetragallane 12 which possibly stabilizes with
The molecular structures of the molecules 3 and 4 in the
formation of unidentified oligogallanes (see above). Sup- crystal are shown in Figure 1 and 2, respectively. In both
port for this suggestion is based on the formation of deca- compounds the Ga atoms of four R*Ga moieties occupy
Ϫ [8]
gallanide R*6Ga10
as an isolable adduct of 12 and 13 the corners of a distorted octahedron together with two
[see also Hsi6Ga10, Hsi ϭ Si(SiMe3)3 [8]] as well as the ‘‘naked’’ Ga atoms. The ‘‘naked’’ Ga atoms are located next
formation of dodecaindane R*8In12 from two molecules to each other, along with the Ga atoms of two further R*
[9]
of the In analog of 13 (Hexaindane R*4In6 — an obvious Ga moieties, at the corners of a distorted square. The Ga
930
Eur. J. Inorg. Chem. 2002, 929Ϫ934

2Ϫ
Octagallane (tBu3Si)6Ga8 and Its Reduction to (tBu3Si)6Ga8
FULL PAPER
atoms that form the Ga6 octahedron and the anellated Ga4
square lie almost in a plane together with the Si atoms of
the four connected R* groups. All quadrangle surfaces
Ga1Ga2Ga7Ga8/Ga5Ga6Ga7Ga8/Ga3Ga5Ga4Ga7/
Ga3Ga6Ga4Ga8 in 3 and 4 are planar (angles sum ca.
360°). The Si atoms connected at the apices of the Ga6 octa-
hedron are tilted towards the square. The two Na(THF)
moieties of 4 bridge opposite edges between the Ga atoms
of the apex and the central plane of the Ga6 octahedron.
Surprisingly, Na(THF) is not located above and below the
Ga4 square, probably due to steric reasons. (Hsi)6Ga10,
which is derived from 4 after exchange of supersilyl for the
sterically less crowded hypersilyl Si(SiMe3)3 and Na(THF)ϩ
by ‘‘isoelectronic’’ Gaϩ, shows a Ga10 framework built from
two anellated Ga6 octahedrons. Scheme 4 shows the struc-
2Ϫ
tural relationships between the octagallanediide R6Ga8
(isolated as 4) and the decagallane R6Ga10 [isolated as
Ϫ
(Hsi)6Ga10][8] via the nonagallanide R6Ga9 {isolated as
[Na(THF)6]ϩ(Hsi)6Ga9Ϫ},[8] which are formally derived
from R6Ga82Ϫ by successive ‘‘neutralization’’ of the dianion
2Ϫ
with Gaϩ cations (it remains to be seen whether R*6Ga8
Scheme 4. Topological relation between R*6Ga22Ϫ, (Hsi)6Ga9, and
(Hsi)6Ga10 [R* ϭ SitBu3, Hsi ϭ Si(SiMe3)3]
is transformed in the presence of a GaI compound into
R*6Ga10 via R*6Ga9Ϫ).
˚
Table 1 presents selected bond lengths [A] and angles [°]
˚
of 3 and 4. The GaϪGa distances (2.41Ϫ2.93 A for 3 and
2.45Ϫ2.76 for 4) lie in the typical range observed in other
[5]
gallium cluster compounds such as R*4Ga4
and
R*8Ga18/R*8Ga22.[1] On reduction of 3 to 4 some of the
GaϪGa bonds lengthen and some shorten, but on average
they remain practically constant (mean bond length of 2.64
A in 3 and 2.61 A in 4). Although the reductions of 3 and
7 with sodium in THF formally proceed in the same man-
ner (R*6Ga8/R*4Ga4 ϩ 2 Na ϩ 2 THF Ǟ Na2Ga8R*6·
2THF/Na2Ga4R*4·2THF), in the first case very little
structural change is observed, whereas in the second case a
drastic structure change and significant GaϪGa bond
shortening occurs.[7] The Ga8 framework of 3 is less sym-
˚
˚
metric than that of
4
(cf. GaϪGa distances). The
Figure 1. View of a molecule of 3 in the crystal (tBu groups ex-
cluded for clarity); for bond lengths and angles see Table 1
˚
NaϪGaR*, NaϪGa, and NaϪO distances are 3.52 A
˚
˚
(mean value), 2.99 A, and 2.31 A (angles sum at Na 357°,
mean value of the GaϪNaϪGa angles 46°), respectively.
Compounds 3 and 4 possess a framework of eight Ga
atoms that was previously unknown for clusters of the
group 13 elements B Ϫ Tl. The isolation of R*6Ga8 (3) and
Tsi6Ga8 (1)[2] shows for the first time that the heavier group
13 elements can also form isomeric clusters that hitherto
were thought to be restricted to boron.
Compound 3 can be described as a conjuncto-octagallane,
based on hexagallane R*4Ga6 (13) and digallene R*2Ga2
(10). Considering the WadeϪMingos rules[11] compound 13
may therefore be classified as a doubly capped tetrahedro-
tetragallane, that is a hypoprecloso-hexagallane [13 possesses
10 cluster electrons (2n Ϫ 2 with n ϭ number of cluster
atoms), giving 1 electron for Ga and two electrons for
GaR*], although this description does not agree at all with
the structure obtained for 3 by X-ray crystallography (see
Table 1).
Figure 2. View of a molecule of 4 in the crystal (tBu and CH2
groups excluded for clarity); for bond lengths and angles see
Table 1
Eur. J. Inorg. Chem. 2002, 929Ϫ934
931

N. Wiberg, T. Blank, H. Nöth, M. Suter, M. Warchhold
FULL PAPER
Table 1. Selected bond lengths and angles of the molecules 3 and 4 in the crystal
[a]
˚
Bond lengths [A]
3
4
Ga7ϪGa8
2.782(3)
2.678(1)
Ga1ϪGa2/Ga5ϪGa6
Ga1ϪGa8/Ga2ϪGa7
Ga5ϪGa8/Ga6ϪGa7
Ga3ϪGa5/Ga3ϪGa6
Ga3ϪGa7/Ga3ϪGa8
Ga4ϪGa5/Ga4ϪGa6
Ga4ϪGa7/Ga4ϪGa8
GaϪSi / SiϪC (av.)
Ga4ϪNa1/Ga7ϪNa1
Ga3ϪNa2/Ga8ϪNa2
Na1ϪO1/Na2ϪO1
2.519(2)/2.561(3)
2.406(3)/2.446(3)
2.638(3)/2.502(3)
2.652(2)/2.713(2)
2.647(2)/2.849(2)
2.614(2)/2.731(2)
2.638(2)/2.925(2)
2.50/1.95
2.535(1)/2.685(1)
2.466(1)/2.453(1)
2.630(1)/2.561(1)
2.757(1)/2.641(1)
2.551(1)/2.592(1)
2.612(1)/2.761(1)
2.628(1)/2.536(1)
2.51/1.96
Ϫ
Ϫ
Ϫ
3.491(3)/2.983(2)
3.544(3)/2.989(2)
2.308(4)/2.308(5)
Bond angles [°] in quadrangles
Ga1/Ga2/Ga7/Ga8
76.60(4)/109.36(4)/
71.16(3)/102.44(4)
98.55(4)/85.97(4)/
96.29(5)/79.11(4)
81.34(7)/98.46(7)/
82.22(7)/97.98(7)
90.18(7)/94.19(7)/
88.25(7)/87.36(7)
92.00(3)/90.93(3)/
88.94(3)/87.38(3)
89.04(3)/90.76(3)/
90.67(3)/89.44(2)
89.35(2)/87.56(2)/
90.90(2)/91.70(3)
90.81(2)/86.92(2)/
89.32(2)/92.88(3)
Ga5/Ga6/Ga7/Ga8
Ga3/Ga5/Ga4/Ga7
Ga3/Ga6/Ga4/Ga8
Bond angles [°] in triangles[b] and at other positions
Ga(base)ϪGa(apex)ϪGa(base) (av.)
Ga(apex)ϪGa(base)ϪGa(base) (av.)
Ga1ϪGa8ϪGa5/Ga2ϪGa7ϪGa6
CϪSiϪC (av.)
O1ϪNa1ϪGa4/Ga7
O2ϪNa2ϪGa3/Ga8
57.45
61.28
175.70(4)/167.11(4)
111.1
Ϫ
60.08
59.96
175.59(3)/174.32(3)
109.9
144.0(2)/163.4(2)
148.0(2)/165.6(2)
46.44
Ϫ
Ϫ
GaϪNaϪGa (av.)
Torsion angles
Ga5ϪGa8ϪGa7ϪGa2
Ga6ϪGa7ϪGa8ϪGa1
Si1ϪGa1ϪGa2ϪSi2
Si5ϪGa5ϪGa6ϪSi6
0.96
2.01
3.34
11.39
3.49
0.88
0.42
5.30
[a]
[b]
Compound numbering from Figures 1 and 2. Apex ϭ Ga3, Ga4; basis ϭ Ga5, Ga6, Ga7, Ga8.
However, 3 may also be derived from the hexagallane
Information about the structures of 3 and 4 in solution
R*6Ga6 Ϫ that should not be preparable for steric reasons is still limited. Only one (broad) NMR signal is found for
Ϫ by substituting two neighbouring R* groups for the six R* groups of 3 in benzene, whereas three NMR
digallanediyl -R*GaϪGaR*. According to its 12 (2n) signals (ratio of areas 1:1:1) are found for 4 in benzene.
cluster electrons, R*6Ga6 should be classified as a mono- This either means that 3 gives equal NMR shifts for the
capped trigonal-bipyramidal closo-Ga5 cluster, that is a pre- nonequivalent R* groups, or that it is fluxional. Low tem-
closo-hexagallane. This description agrees with the solid- perature NMR studies of 3 in solution are planned. In addi-
state structure found for 3 (Table 1). The long Ga8ϪGa3/ tion, NMR studies of 4 in donor solvents D may confirm
ϩ
Ga4/Ga7 distances of the R*4Ga6 moiety of 3 suggest that the expected dissociation of the cluster into Na(D)n and
2Ϫ
R*4Ga6 contains a trigonal-bipyramidal Ga3Ga4Ga5- R*6Ga8 ions.
Ga6Ga7 cluster with Ga8 as the edge-bridging atom. By
the same reasoning, the octagallanediide 4 may be de-
scribed as a derivative of the closo-octagallanediide R*6
Ga6 [14 (2n ϩ 2) cluster electrons] by substituting two
Experimental Section
2Ϫ
neighbouring R* groups for -R*GaϪGaR*-, and in fact
the R*4Ga6 moiety of 4 shows a more regular (octahed-
All experiments were carried out in flame-dried glass apparatus
with standard Schlenk techniques under dry argon or nitrogen. Air
2Ϫ
ral) Ga6 framework than the R*4Ga6 moiety of 3 (Table 1). and moisture were strictly excluded. The solvents (heptane, ben-
932 Eur. J. Inorg. Chem. 2002, 929Ϫ934

2Ϫ
Octagallane (tBu3Si)6Ga8 and Its Reduction to (tBu3Si)6Ga8
FULL PAPER
zene, THF) were dried with sodium plumbide or sodium in the
presence of benzophenone. Available for use: C6D6. The following
compounds were synthesized according to literature procedures:
and H atoms were included in the final refinement at calculated
positions using a riding model and fixed isotropic Ui values. A
semiempirical absorption correction was applied by using the pro-
gram SADABS. The structures of 3 and 4 are shown in Figure 1
and 2, crystallographic details are summarized in Table 2.
CCDC-165237 (3) and CCDC-165238 (4) contain the supplement-
ary crystallographic data for this paper. These data can be obtained
free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or
from the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK; fax: (internat.) ϩ 44-1223/336-
033; E-mail: deposit@ccdc.cam.ac.uk].
R*4Ga3 (3),[4] NaC10H8 in THF.[12]
·
NMR Spectra: Jeol GX-270 (1H/13C/29Si: 270.17/67.94/
53.67 MHz), Jeol EX-400 (1H/13C/29Si: 399.78/100.54/79.43 MHz).
The NMR spectra were recorded with the INEPT and DEPT pulse
sequences using empirically optimized parameters for the men-
tioned groups.
Synthesis of R*6Ga8 (3): A solution of 5 (0.151 g, 0.130 mmol) in
5 mL of heptane was kept 25 h at 60 °C, after which time it had
quantitatively decomposed into R*H,[13] R*2,[13] 6,[4] 7,[5] and 3 (ra-
1
tio of H NMR signal areas of the R* groups of molecules R*H,
Table 2. Selected parameters of the X-ray structure analyses of the
compounds 3 and 4
R*2, 7, 3 about 1:1:5:3, corresponding to a mol ratio of the com-
1
pounds of about 4:2:5:2) according to ESR, and H, 13C and 29Si
3
4
NMR spectroscopy. After the removal of all volatile compounds
under vacuum and dissolving the residue in 2 mL of benzene, com-
pound 3 (0.115 g, 0.066 mmol, 15%) was obtained after eight days
at 8 °C as water- and air-sensitive dark-blue crystals. 1H NMR
(C6D6): δ ϭ 1.28 (broad, 162 H, 6 SitBu3). 13C{1H} NMR (C6D6):
δ ϭ 25.6/33.6 (broad/broad, 18 C/54 C, 18 CMe3/18 CMe3). 29Si
NMR (C6D6): δ ϭ 58.7 (broad, 6 Si, 6SitBu3). X-ray structure ana-
lysis: see Figure 1 (blue prisms from benzene). Note: The relative
yields of 6 (seen only by ESR spectroscopy), 7 and 3 (seen only
by NMR spectroscopy) depend, amongst others, on the reaction
temperature. According to the NMR spectra, 7 and 3 are formed
from 5 in heptane after 25 h at 40 or 60 or 100 °C in the mol ratio
of about 99:1 or 71:29 or 100:0 (3 is thermolabile at 100 °C).
Empirical formula
Mr
System
C72H162Ga8Si6
1754.32
monoclinic
P21/c
25.02(2)
16.18(2)
25.53(3)
90
C92H190Ga8Na2O2Si6
2100.72
triclinic
¯
Space group
P1
˚
a [A]
16.641(2)
16.717(2)
21.589(2)
91.996(2)
90.194(2)
113.033(2)
5525(1)
˚
b [A]
˚
c [A]
α [°]
β [°]
γ [°]
118.195(1)
90.000
9110(2)
3
˚
V [A ]
Z
4
2
D [Mg mϪ3
]
1.279
2.441
3704
3.10Ϫ46.50
Ϫ21 Յ h Յ 22
Ϫ17 Յ k Յ 17
Ϫ28 Յ l Յ 28
37958
10435
7428
0.0496
0.8372/0.5403
0.0706
0.0965
0.980
1.263
2.032
2224
1.88Ϫ58.26
Ϫ20 Յ h Յ 20
Ϫ20 Յ k Յ 22
Ϫ27 Յ l Յ 28
32188
16939
10368
0.0495
0.6946/0.6205
0.0439
0.0878
0.951
µ [mmϪ1
F(000)
2θ [°]
]
Thermolysis of R*6Ga8 (3): A solution of 3 (0.073 g, 0.042 mmol)
in 0.6 mL of C6D6 was kept for 14 h at 100 °C. After this time,
according to the 1H/13C/29Si NMR spectra, 3 had quantitatively
decomposed into R*H,[13] R*2,[13] 7,[5] and an unidentified com-
Ranges [°]
1
pound RmGan (ratio of H NMR signal areas of the R* groups of
molecules R*H, R*2, 7, RmGan about 2:1:10:(4ϩ2), corresponding
to a mol ratio of R*H, R*2 and 7 of about 4:1:5). In addition, an
insoluble product was formed (oligogallane ?). Characterization of
the dissolved RmGan: 1H NMR (C6D6): δ ϭ 1.39 (broad). 13C{1H}
NMR (C6D6): δ ϭ 25.59/26.01 (s/s, 2x C/x C, 2x CMe3/x CMe3),
30.27/33.45 (s/s, 6x C/3x C, 2x CMe3/x CMe3). 29Si NMR (C6D6):
δ ϭ 43.28/56.70 (s/s, 2x Si/x Si, 2x SitBu3/x SitBu3). Note: Octagal-
lane R*6Ga8 with the structure of R*6In8 (2) should give a ratio of
SitBu3 NMR signal areas of 2:1).
All reflections
Independent
Observed[a]
Rint
x/y[a]
R1 [F Ͼ 4σ(F)]
[a]
wR2 [F Ͼ 4σ(F)]
GOOF(F2)
Max./min. electron
0.8372/Ϫ0.5403
0.6946/Ϫ0.6205
Ϫ3
˚
density[e·A
]
Synthesis of Na2Ga8R*6·2THF (4):
A solution of NaC10H8
[a]
2
2
2
wϪ1 ϭ σ2F0 ϩ (xP)2 ϩ yP with P ϭ (F0 ϩ 2Fc )/3.
(0.11 mmol) in 1.5 mL of THF was added dropwise to a solution
of 3 (0.05 mmol) in 10 mL of THF at Ϫ78 °C. After 5 h stirring at
Ϫ78 °C all volatile components were removed from the reaction
mixture under vacuum at Ϫ45 °C and the residue was dissolved in
3 mL of C6D6. This solution was concentrated to 0.8 mL and
water- and air-sensitive red crystals of 4 were obtained after two
Acknowledgments
1
months at 5 °C. H NMR (C6D6): δ ϭ 1.289/1.367/1.380 (s/s/s, 54
We thank the Deutsche Forschungsgemeinschaft and the Fonds der
Chemischen Industrie for support of our research.
H/54 H/54 H, 2 SitBu3/2 SitBu3/2 SitBu3), 1.124/3.325 (m/m, 8 H/
8 H, 4 CH2/4 CH2O). 29Si{1H} NMR (C6D6): δ ϭ 43.8/47.1/51.2
(s/s/s, 2Si/2Si/2Si, 2 SitBu3/2 SitBu3/2 SitBu3). X-ray structure ana-
lysis: see Figure 2 (red prisms from benzene).
[1]
A. Donchev, A. Schnepf, G. Stößer, E. Baum, H. Schnöckel,
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A. Schnepf, R. Köppe, H. Schnöckel, Angew. Chem. 2001, 113,
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(Mo-Kα radiation λ ϭ 0.71073 A). Crystals were mounted in per-
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fluoropolyether oil and data collected at T ϭ 188(2) (3) and 193(2)
K (4). The structures were solved by direct methods (SHELXS-97)
and refined with full-matrix procedures against F2 for all observed
reflections. All non-hydrogen atoms were refined anisotropically
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N. Wiberg, T. Blank, A. Purath, G. Stößer, H. Schnöckel, An-
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Eur. J. Inorg. Chem. 2002, 929Ϫ934
933

N. Wiberg, T. Blank, H. Nöth, M. Suter, M. Warchhold
FULL PAPER
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Habereder, W. Kaim, M. Wanner, Eur. J. Inorg. Chem. 2001,
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N. Wiberg, K. Amelunxen, H.-W. Lerner, H. Nöth, W.
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See standard text books on inorganic chemistry, for example
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J. L. Wardell, in Comprehensive Organometallic Chemistry
(Eds.: G. Wilkinson, F. G. Stone), Vol. 1, Pergamon, Oxford,
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Wiberg, Organometallics 2001, 20, 860Ϫ868.
N. Wiberg, T. Blank, H. Nöth, W. Ponikwar, Angew. Chem.
[9]
Received October 2, 2001
1999, 111, 887Ϫ890; Angew. Chem. Int. Ed. 1999, 38, 839Ϫ841.
[I01386]
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Eur. J. Inorg. Chem. 2002, 929Ϫ934