Photodecompostion of the Oligogermanes nBu3GeGePh2GenBu3 and nBu3GeGePh3: Identification of the Photoproducts by Spectroscopic and Spectrometric Methods

Article abstract of DOI:10.1002/ejic.201600421

The oligogermane nBu₃GeGePh₂GenBu₃was photolyzed using UV-C light in the presence of acetic acid as a trapping agent and the photoproducts were identified using¹H NMR spectroscopy, gas chromatography/electron-impact mass spectrometry, and high resolution accurate mass mass spectrometry. The products identified were the germanes nBu₃GeH, nBu₃GeOAc, and Ph₂Ge(H)OAc (OAc = C₂H₃O₂) and the digermane nBu₆Ge₂. This indicates that both germanium–germanium single bonds are cleaved homolytically upon irradiation to generate two nBu₃Ge^·radicals and the germylene Ph₂Ge:. The digermane nBu₃GeGePh₃was also photolyzed under identical conditions, and in this case the photoproducts were identified as nBu₃GeH, nBu₃GeOAc, Ph₃GeH, Ph₃GeOAc and the digermanes nBu₆Ge₂and Ph₆Ge₂.

Full text of DOI:10.1002/ejic.201600421

DOI: 10.1002/ejic.201600421
Full Paper
Oligogermanes
Photodecompostion of the Oligogermanes nBu3GeGePh2GenBu3
and nBu3GeGePh3: Identification of the Photoproducts by
Spectroscopic and Spectrometric Methods
Sangeetha P. Komanduri,[a] Aaron C. Schrick,[a] Christa L. Feasley,[b] Craig P. Dufresne,[b] and
Charles S. Weinert*[a]
Abstract: The oligogermane nBu3GeGePh2GenBu3 was photo- mane nBu6Ge2. This indicates that both germanium–germa-
lyzed using UV-C light in the presence of acetic acid as a trap- nium single bonds are cleaved homolytically upon irradiation
ping agent and the photoproducts were identified using 1H to generate two nBu3Ge· radicals and the germylene Ph2Ge:.
NMR spectroscopy, gas chromatography/electron-impact mass The digermane nBu3GeGePh3 was also photolyzed under identi-
spectrometry, and high resolution accurate mass mass spec- cal conditions, and in this case the photoproducts were identi-
trometry. The products identified were the germanes nBu3GeH, fied as nBu3GeH, nBu3GeOAc, Ph3GeH, Ph3GeOAc and the diger-
nBu3GeOAc, and Ph2Ge(H)OAc (OAc = C2H3O2) and the diger- manes nBu6Ge2 and Ph6Ge2.
Introduction
nBu3GeGePh2GenBu3 (1) and have photolyzed this compound
in the presence of acetic acid.
It was expected that photolysis of 1 would yield several pho-
toproducts that would be the trapping products of both radi-
cals and germylenes generated during the reaction, including
nBu3GeH, nBu3GeOAc from generation of the tributylgermyl
radical, and also Ph2Ge(H)OAc and also possibly nBu2Ge(H)OAc
from extrusion of the germylenes Ph2Ge: and nBu2Ge:, respec-
tively. If any trapped Ph2Ge: were identified as Ph2Ge(H)OAc,
the presence of different substituents at the germanium atoms
of 1 would indicate that the source of this germylene would be
the central germanium atom of 1. Similarly, if nBu2Ge(H)OAc
were obtained then the germylene nBu2Ge: would be gener-
ated from the terminal germanium atoms of 1. Ligand scram-
bling processes also might be expected to occur, and any result-
ing mixed-ligand radicals or germylenes that were produced
also could be trapped and identified. The photoproducts from
The photochemistry of catenated group 14 compounds is of
interest since this method can be used to convert one type of
catenate to another and also can be used for the generation of
reactive intermediates including silylenes, germylenes, stannyl-
enes, and group 14 element centered radical species that can
be trapped and characterized.[1–33] In the case of germanium,
[34]
the photochemistry of the cyclotrigermane (Mes2Ge)3
has
been the most extensively studied and it has been shown that
this compound is photochemically converted to a germylene
Mes2Ge: and a digermene Mes2Ge=GeMes2. The chemistry of
both of these photoproducts has been thoroughly investi-
gated.[1,2,4,13,14,35–42] However, only a few investigations into the
photochemistry of linear oligogermanes have been described.
These include the photolysis of the permethylated oligoger-
manes Me(GeMe2)nMe (n = 3–6)[7,9] and the polygermanes
(R2Ge)n (R2 = Et2, nBu2, Hex2, PhMe).[8,14]
1
1 have been characterized by H NMR spectroscopy, gas chro-
matography/electron impact mass spectrometry (GC/MS), and
high resolution accurate mass mass spectrometry (HRAM-MS).
The photochemistry of the related digermane nBu3GeGePh3 (2)
has also been studied. We have found that HRAM-MS is a highly
useful tool for the study of these photoproduct mixtures and is
used here for the first time in this regard.
It has been shown that linear oligogermanes decompose via
both the homolytic scission of the Ge–Ge bonds to yield germyl
radicals, by germylene extrusion with concomitant chain con-
traction, or by a combination of both processes. The photo-
chemistry of heteroleptic oligogermanes, where the substituent
pattern is different at different germanium atoms, has yet to
be explored. In this regard, we have prepared the trigermane
Results and Discussion
[a] Department of Chemistry, Oklahoma State University,
Stillwater, Oklahoma 74078, USA
Synthesis and Characterization of Materials
E-mail: charles.s.weinert@okstate.edu
The trigermane 1 and the digermane 2[43] were synthesized
using the hydrogermolysis reaction as shown in Scheme 1,
where the starting germanium amide reagent is converted in
situ to an α-germyl nitrile that is the active species in the ger-
weinertlab.okstate.edu
[b] Thermo Fisher Scientific,
1400 Northpoint Parkway Suite 10, West Palm Beach, Florida 33407, USA
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/ejic.201600421.
Eur. J. Inorg. Chem. 0000, 0–0
1
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
manium–germanium bond forming process.[43–46] The possible 1.93 ppm persisted indicating that AcOH was still present in the
germylene trapping products Ph2Ge(H)OAc (3) and reaction mixture although the singlet at δ = 12.00 ppm had
nBu2Ge(H)OAc (4) were prepared from the corresponding ger- broadened into the baseline. Irradiation for a further 3 h did not
manium hydrochlorides R2GeHCl[47] and silver acetate, while result in any additional observable changes in the spectrum.
nBu3GeOAc (5) was prepared from nBu3GeCl and silver acetate
(Scheme 2). The acetate-containing compounds exhibit charac-
teristic resonances of the acetate methyl group hydrogen atoms
1
in their H NMR spectra at δ = 1.86 (3), 1.86 (4), and 1.90 ppm
(5). The germanium-bound hydrogen atom in 3 results in the
1
observation of a singlet at δ = 6.72 ppm in the H NMR spec-
trum of 3, while that for 4 appears as a pentet at δ = 5.71 ppm.
Scheme 1.
Scheme 2.
1
Investigation of the Photochemistry of 1 by H NMR
Spectroscopy
The trigermane 1 was dissolved in [D12]cyclohexane in a quartz
NMR tube in the presence of 2 equiv. of AcOH and was irradi-
Figure 1. 1H NMR spectra for the phtoloysis of nBu3GeGePh2GenBu3 (1) in the
presence of AcOH in [D12]cylcohexane at various time intervals.
ated at regular intervals with UV-C light after which the 1H NMR
1
spectrum of the sample was recorded. The H NMR spectra re-
corded at four different exposure times are shown in Figure 1.
The trigermane 1 was also irradiated for 18 h with UV-C light
After irradiation of the sample for 3 min a noticeable decrease in THF solution in the presence of 10 equiv. of acetic acid
1
in the intensity of the signals for AcOH at δ = 12.00 and (AcOH). After workup to remove the excess AcOH the H NMR
1.93 ppm and the appearance of a multiplet at δ = 3.79 and a spectrum in [D6]benzene contained a complex pattern of peaks
singlet at δ = 1.88 ppm was observed, and these two resonan- in the alkyl and aryl region of the spectrum indicting the pres-
ces continued to increase in intensity as the photolysis was con- ence of multiple photoproducts. However, there were two
tinued. After a total irradiation time of 15 min two additional clearly visible singlets at δ = 6.72 and 1.78 ppm indicating the
singlets at δ = 6.52 and 1.99 ppm had appeared and these are presence of 3, as well as an additional singlet at δ = 1.90 ppm
assigned to the germanium-bound hydrogen and the acetate and a multiplet at δ = 4.02 ppm (J = 3.0 Hz). Given these results
methyl group of Ph2Ge(H)OAc (3), respectively.[5] The four sig- and those from the NMR scale experiment described above, it
nals at δ = 6.52, 3.79, 1.99, and 1.88 ppm continued to increase was postulated that the singlet at δ = 1.90 ppm and the multip-
in intensity as the photolysis experiment was continued until a let at δ = 4.02 ppm might be attributed to either the germylene
total irradiation time of 120 min, after which no further change trapping product nBu2Ge(H)OAc (4) that could be generated by
in the 1H NMR spectrum was observed. The singlet at δ = extrusion of nBu2Ge: from the terminal nBu3Ge-groups of 1, or
Eur. J. Inorg. Chem. 0000, 0–0
www.eurjic.org
2
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
the multiplet alone could be due to the presence of the ger-
The mass spectrum of fourth compound eluted (tr =
mane nBu3GeH (6) while the singlet results from a separate 29.9 min) exhibits a peak at m/z = 431 that is assigned to the
+
species containing an acetate group. The multiplet is identical nBu5Ge2 ion, and four additional peaks were observed that
to that observed in the 1H NMR spectrum of a commercial sam- correspond to the successive fragmentation of four butyl
ple of 6, and thus the singlet δ = 1.90 ppm must be due to the groups from this ion. This indicates that the digermane nBu6Ge2
presence of another acetate-containing species. The acetate 5 (7) is present in the photolysis product mixture. The GC/MS
exhibits an identical singlet at δ = 1.90 ppm for the methyl of a synthetically prepared sample of 7[48] exhibited the same
group protons and so 5 also appears to be present in the pho- retention time and mass spectrum confirming that 7 is present
tolysis product mixture of 1.
in the photolysis product mixture. The mass spectrum of the
fifth species eluted (tr = 44.9 min) contained a peak at m/z =
394 that is assigned to the nBu3GeGePh+ ion, as well as peaks
at m/z = 338, 282, and 225 resulting from fragmentation of this
ion via the successive loss of all three butyl groups. This mate-
rial is unreacted 1 that remained in the photolysis product mix-
ture. The two most abundant species in the GC trace of the
photolysis product mixture of 1 are 6 and the digermane 7.
Investigation of the Photochemistry of 1 by Mass
Spectrometry
The photolysis product mixture for 1 was analyzed using elec-
tron impact GC/MS. The GC trace for the product mixture exhib-
ited five peaks with retention times of 10.9, 16.4, 23.7, 29.9, and
44.9 min and the GC/MS data are collected in Table 1. Although
phenyl-substituted germanes were also present in the product
mixture, any of these species that are present decompose un-
der the thermal conditions of the GC column. The mass spec-
trum of the first compound eluted had three main peaks at
m/z = 189, 133, and 75. These are assigned to the nBu2GeH+,
nBuGeH2+, and GeH+ ions, while the two peaks at m/z = 132
and 75 are assigned to the nBuGeH+ and GeH+ ions resulting
from fragmentation of the nBu2GeH+ ion. The retention time
and mass spectrum are identical to that of a pure sample of
nBu3GeH run under identical conditions, and so the first com-
pound eluted is 6.
Analysis of the photolysis product mixture of 1 by High Reso-
lution Accurate Mass Mass Spectrometry (HRAM-MS) resulted in
the observation of six intense peaks at m/z = 230.0964,
245.1325, 270.0337, 286.1588, 305.0385, and 346.0652 (Figure 2,
Table 2). These are assigned to the nBu2GeH(CH3CN)+,
nBu3Ge+, Ph2GeH(CH3CN)+, nBu3Ge(CH3CN)+, Ph3Ge+, and
Ph3Ge(CH3CN)+ ions, respectively. A less intense signal at m/z =
565.1749 was also observed that corresponds to the
nBu3GeOGenBu3H+ ion that is generated by insertion of oxygen
into the germanium–germanium bond of 7 under the experi-
mental MS conditions. A weak signal at m/z = 731.2704 due
to the nBu3GeGePh2GenBu3H3O+ ion indicates the presence of
unphotolyzed 1.
Table 1. EI-GC/MS data for photolyzed nBu3GeGePh2GenBu3 (1).
The HRAM-MS of unphotolyzed 1 contains a signal at m/z =
368.2119 corresponding to the nBu3Ge(CH3CN)3+ ion, as well as
a less intense signal at m/z = 594.2128 due to the presence of
the nBu3GeGePh2(CH3CN)3+ ion (Table 2). This indicates that the
oligogermanes do not remain intact under the experimental
MS conditions. However, the nBu3Ge+ fragment was observed
in the HRAM-MS of both photolyzed and unphtopholyzed 1,
indicating that this species could be produced from unreacted
1 or the germanes nBu3GeOAc (5) and/or nBu3GeH (6).
Area %
85.6
m/z
Assignment
nBu3GeH (6)
(tr = 10.9 min)
189
133
75
nBu2GeH+
+
nBuGeH2
GeH+
nBu3GeOGenBu3
(tr = 16.4 min)
1.8
2.5
223
167
131
265
209
153
431
375
319
263
207
394
338
282
225
nBu2GeO(H3O)+
nBuHGeO(H3O)+
nBuGe+
nBu3GeOAc (5)
(tr = 23.7 min)
nBu2Ge(C2H3O2)(H2O)+
nBuGe(C2H3O2)(H2O)H+
+
Ge(C2H3O2)(H2O)H2
+
nBu3GeGenBu3 (7) 7.6
(tr = 29.9 min)
Ge2nBu5
Synthetically prepared 5 and a commercial sample of 6 were
also analyzed by HRAM-MS. The most intense peak in the
HRAM-MS of 5 was at m/z = 327.1342 that is assigned to the
Ge2nBu4H+
+
Ge2nBu3H2
Ge2nBu2H3
Ge2nBuH4
+
+
+
nBu3Ge(CH3CN)2 ion, and a weak but observable signal at
1
2.5
nBu3GeGePh+
nBu2HGeGePh+
nBuH2GeGePh+
HGeGePh+
m/z = 428.2320 corresponds to the nBu3GeOAc(CH3CN)3H+ ion.
The MS/MS of the nBu3GeOAc(CH3CN)3H+ ion contains two sig-
nals at m/z = 368.2113 and 327.1847 resulting from fragmenta-
(tr = 44.9 min)
+
+
tion to the nBu3Ge(CH3CN)3 and nBu3Ge(CH3CN)2 ions, re-
spectively. Therefore, although no solvated 5 was observed in
the HRAM-MS of the photolysis product mixture of 1, the non-
solvated and mono-solvated nBu3Ge+ ion that was detected
could also be generated from 5. The HRAM-MS of a commercial
sample of 6 contains signals at m/z = 286.1582 and 505.2684
corresponding to the nBu3Ge(CH3CN)+ and nBu3GeOGenBu3H+
ions, respectively, indicating that both of these species that
were detected in the photolysis product mixture of 1 could
arise from the presence of 6.
The mass spectrum of the second compound eluted (tr =
16.4 min) exhibited significant peaks at m/z = 223, 167, and 131
that correspond to the nBu2GeO(H3O)+, nBuHGeO(H3O)+, and
nBuGe+ ions that are likely generated by the fragmentation of
nBu3GeOGenBu3, which is formed from the insertion of oxygen
into the Ge–Ge bond of nBu6Ge2 (7) under the experimental
conditions. The mass spectrum of the third compound eluted
(tr = 23.6 min) exhibited peaks at m/z = 265, 209, and 153 that
are assigned to the nBu2Ge(C2H3O2)(H2O)+, nBuGe(C2H3O2)-
(H2O)H+, and Ge(C2H3O2)(H2O)H2+ ions indicating that the third
compound eluted is nBu3GeOAc (5).
The HRAM-MS of Ph2Ge(H)OAc 3 contained a signal at m/z =
270.0239 due to the Ph2Ge(CH3CN)H+ ion that is identical to
Eur. J. Inorg. Chem. 0000, 0–0
www.eurjic.org
3
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
Figure 2. High resolution accurate mass mass spectra (HRAM-MS) of six components of the photolysis product mixture of nBu3GeGePh2GenBu3 (1):
nBu2Ge(CH3CN)H+ (a), nBu3Ge+ (b), Ph2Ge(CH3CN)H+ (c), nBu3Ge(CH3CN)H+ (d), Ph3Ge+ (e), Ph3Ge(CH3CN)H+ (f).
the signal observed in the HRAM-MS of the photolysis product nBu4Ge2(H2O)H+ ions, respectively. The signal at 230.0968 was
mixture of 1. However, the most intense peak in the HRAM- also observed in the photolysis product mixture of 1, but in
MS of 3 was at m/z = 473.0180 that is assigned to the ion this case it is likely that this species is generated from the frag-
Ph3Ge2(CH3CN)(H2O)3H+. This ion is generated under the experi- mentation of the free and solvated nBu3Ge+ that is present. The
mental MS conditions, and analysis of this ion by MS/MS shows MS/MS of the nBu3Ge(CH3CN)3+ ion generates free nBu3Ge+ and
that it fragments into Ph3Ge+ at m/z = 305.0374, as well as the also nBu2Ge(CH3CN)H+ even under the lowest energy MS/MS
daughter ions Ph2Ge(OH)+ at m/z = 245.0012 and Ph2GeH+ at conditions. Given these observations and the fact that the pen-
m/z = 270.0239. Therefore, the ion observed at m/z = 305.0385 tet for the germanium-bound hydrogen in 4 was not observed
in the photolysis product mixture of 1 is most likely generated in the photolysis product mixture of 1, the germylene nBu2Ge:
under the conditions of the mass spectrometer and is not due is not being photolytically produced from 1.
to the presence of a photoproduct. Rather, this ion is observed
as a result of the presence of 3 in the photolysis product mix-
ture.
Photolysis of the Digermane nBu3GeGePh3 (2)
The HRAM-MS of the other possible germylene trapping The photolysis of the digermane nBu3GeGePh3 (2) was also in-
product nBu2Ge(H)OAc (4) was also obtained and the two most vestigated. A sample of 2 was irradiated in THF solution for 18 h
intense signals for 4 were observed at m/z = 230.0968 and in the presence of 10 equiv. AcOH. After workup of the reaction
393.1447. These correspond to the nBu2Ge(CH3CN)H+ and mixture in the same manner as for 1 the 1H NMR spectrum
Eur. J. Inorg. Chem. 0000, 0–0
www.eurjic.org
4
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
Table 2. HRAM-MS data for photolyzed nBu3GeGePh2GenBu3 (1).
Observed
Calculated
Δmass (ppm)
Assignment
1 (photolyzed with 10 equiv. AcOH)
230.0964
286.1588
270.0337
305.0385
346.0652
565.1749
731.2704
230.0959
286.1585
270.0333
305.0380
346.0646
565.1741
731.2861
2.173
1.048
1.481
1.639
1.733
1.415
21.47
nBu2Ge(CH3CN)H+
nBu3Ge(CH3CN)+
Ph2Ge(CH3CN)H+
Ph3Ge+
Ph3Ge(CH3CN)+
nBu3GeOGenBu3H+
1H3O+
+
1 (unphotolyzed)
Ph2Ge(H)OAc (3)
368.2110
594.2128
999.4687
368.2116
594.2119
999.4536
1.629
1.514
15.11
nBu3Ge(CH3CN)3
+
nBu3GeGePh2(CH3CN)3
+
1(CH3CN)7
229.0065
270.0329
473.0180
229.0067
270.0333
473.0261
0.8733
1.481
17.12
Ph2GeH+
Ph2Ge(CH3CN)H+
Ph3Ge2(CH3CN)(H2O)3H+
nBu2Ge(H)OAc (4)
nBu3GeOAc (5)
nBu3GeH (6)
230.0968
393.1447
230.0959
393.1428
3.911
4.832
nBu2Ge(CH3CN)H+
nBu4Ge2(H2O)H+
428.2320
327.1342
428.2327
327.1850
6.134
155.2
nBu3GeOAc(CH3CN)3H+
+
nBu3Ge(CH3CN)2
286.1582
505.2684
286.1585
505.2683
1.048
0.1979
nBu3Ge(CH3CN)+
nBu3GeOGenBu3H+
was recorded in [D6]benzene. The aryl and alkyl regions of the
spectrum were again complex, but diagnostic resonances were
present at δ = 5.85 (s), 4.02 (sept, J = 3.0 Hz), 1.90 (s), and
1.81 ppm. These data indicate the presence of the four ger-
manes Ph3GeH, nBu3GeH (6), nBu3GeOAc (5), and Ph3GeOAc,
where the peak at δ = 1.81 ppm matches that of a commercial
sample of Ph3GeOAc.
The GC/MS of the photolysis product mixture of 2 indicated
the presence of both nBu3GeH (6) and nBu6Ge2 (7) that had
identical retention times and mass spectra as found in the pho-
tolysis product mixture of 1 (Table 3). In addition, two other
significant peaks with retention times of 13.4 and 23.6 min cor-
responding to nBu3GeOGenBu3 and nBu3GeOAc (5) were ob-
served that had identical mass spectra for these components
present in the photolysis product mixture of 1. However, the
three most abundant components in the GC trace for 2 are 6,
nBu3GeOGenBu3 and nBu3GeOAc (5).
Table 3. EI-GC/MS data for photolyzed nBu3GeGePh3 (2).
Area %
70.1
m/z
Assignment
nBu3GeH (6)
(tr = 10.9 min)
189
133
75
nBu2GeH+
+
nBuGeH2
GeH+
nBu3GeOGenBu3
(tr = 16.4 min)
11.3
11.7
1.7
223
167
131
nBu2GeO(H3O)+
nBuHGeO(H3O)+
nBuGe+
nBu3GeOAc (5)
(tr = 23.7 min)
265
209
153
nBu2Ge(C2H3O2)(H2O)+
nBuGe(C2H3O2)(H2O)H+
Ge(C2H3O2)(H2O)H2
+
+
nBu3GeGenBu3 (7)
(tr = 29.9 min)
431
375
319
263
207
Ge2nBu5
Ge2nBu4H+
+
Ge2nBu3H2
Ge2nBu2H3
Ge2nBuH4
+
+
The GC also contained six trace components with longer re-
tention times, and we have identified two of these species. The
component with tr = 40.2 min contains the Ph3Ge+ ion (m/z =
305) and daughter ions resulting from the fragmentation of the
phenyl groups. This species is due to the presence of Ph6Ge2 in
the product mixture that is formed by the coupling of two
Ph3Ge· radicals, which was confirmed by the analysis of a com-
mercial sample of Ph6Ge2 that exhibited the same retention
time and mass spectrum. The mass spectrum of the component
with tr = 42.7 min contained the Ph3Ge2H2+ ion (m/z = 379) and
this is due to the presence of unreacted 2 in the product mix-
ture, which was confirmed by analysis of a sample of pure 2.
The mass spectrum also contains signals for the nBu2GeH+ and
Ph6Ge2
(tr = 40.2 min)
0.9
0.5
305
228
151
Ph3Ge+
Ph2Ge+
PhGe+
+
2
379
305
189
151
133
Ph3Ge2H2
(tr = 42.7 min)
Ph3Ge+
nBu2GeH+
PhGe+
+
nBuGeH2
Trace components
3.8
and nBu3Ge(CH3CN)+ ions, respectively. The latter ion results
from the presence of 5, 6, 7, and unreacted 2 in the product
mixture, while the Ph3Ge+ ion is formed from Ph3GeH, Ph6Ge2,
+
nBuGeH2 ions.
The HRAM-MS of the photolysis product mixture of 2 con- and Ph3GeOAc and unreacted 2. A third significant signal at
tained signals at m/z = 305.0383 and 286.1588 for the Ph3Ge+ m/z = 452.9151 corresponds to the nBuPh3Ge2(H3O)+ ion that is
Eur. J. Inorg. Chem. 0000, 0–0
www.eurjic.org
5
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
Scheme 3.
ysis experiments were conducted using a Luzchem photolysis panel
equipped with five UV-C lamps. GC/MS data were acquired using a
Shimadzu QP2010 GC/MS and HRAM-MS data were collected using
a Thermo Fisher Q ExactiveTM Hybrid Quadruple-OrbitrapTM Mass
Spectrometer. Elemental analyses were conducted by Galbraith Lab-
oratories.
also attributable to the presence of unreacted 2 in the product
mixture.
Conclusions
1
Based on the H NMR and mass spectrometric data, the triger-
nBu3GeGePh2GenBu3 (1): To a solution of nBu3GeNMe2 (1.385 g,
4.810 mmol) in acetonitrile (15 mL) was added a solution of
Ph2GeH2 (0.500 g, 2.18 mmol) in acetonitrile (10 mL). The reaction
mixture was sealed in a Schlenk tube fitted with a Teflon® stopper
and was stirred under nitrogen for 48 h at 85 °C. The acetonitrile
was removed in vacuo and the resulting oil was vacuum distilled in
a Kugelrohr oven (125 °C, 0.10 Torr) to yield 1 (0.992 g, 64 %) as a
mane 1 decomposes by the homolytic scission of both Ge–Ge
single bonds to generate two nBu3Ge· radicals as well as the
germylene Ph2Ge: (Scheme 3). The tributylgermyl radicals are
trapped by acetic acid to form the germane nBu3GeH (6) as the
major product as well as nBu3GeOAc (5). The nBu3Ge· radicals
also combine to generate the digermane nBu6Ge2 (7), while
diphenylgermylene is trapped by acetic acid to provide the ger-
mane Ph2Ge(H)OAc (3). No evidence was found for the genera-
tion of the germylene nBu2Ge: that would be trapped by acetic
acid to provide the germane nBu2Ge(H)OAc (4).
The digermane 2 also decomposes by homolytic scission of
the Ge–Ge single bond to provide the radicals nBu3Ge· and
Ph3Ge·. In this case, both of these radical species react with
acetic acid to provide the corresponding germanes 6 and
Ph3GeH as well as the acetate species 5 and Ph3GeOAc. Two
nBu3Ge· radicals also combine to yield the digermane 7 and
also two Ph3Ge· radicals also combine to provide the digermane
Ph6Ge2.
1
colorless oil. H NMR (C6D6, 23 °C): δ = 7.73 (d, J = 8.4 Hz, 6 H, o-
H), 7.22 (m, 6 H, m-H), 7.14 (d, J = 7.8 Hz, 3 H, p-H), 1.49 (m, 6 H,
-CH2CH2CH2CH3), 1.34 (q, J = 7.2 Hz, 6 H, -CH2CH2CH2CH3), 1.19 (m,
6 H, -CH2CH2CH2CH3), 0.90 (t, J = 7.2 Hz, 9 H, -CH2CH2CH2CH3) ppm.
13C NMR (C6D6, 23 °C): δ = 140.7 (ipso-C), 136.1 (o-C), 128.3 (p-C),
128.1 (m-C), 28.8 (-CH2CH2CH2CH3), 27.1 (-CH2CH2CH2CH3), 15.0
(-CH2CH2CH2CH3), 13.9 (-CH2CH2CH2CH3) ppm. C36H64Ge3 (714.67):
calcd. C 60.47, H 9.03; found C 60.35, H 9.11.
Ph2Ge(H)OAc (3): A Schlenk flask covered with aluminum foil was
charged with Ph2GeHCl[47] (0.27 g, 1.0 mmol) in 5 mL on benzene.
To this solution was added AgOAc (0.22 g, 1.3 mmol) in the dark as
a suspension in 10 mL of benzene. The reaction mixture was stirred
in the dark for 12 h and then was filtered through Celite. The sol-
vent was evaporated from the filtrate in vacuo to yield 3 (0.25 g,
85 %) as a colorless oil. 1H NMR (C6D6, 25 °C): δ = 7.65 (t, J = 7.9 Hz,
4 H, o-C6H5), 7.16–7.11 (m, 6 H, m-C6H5 and p-C6H5), 6.72 (s, 1 H,
Ge-H), 1.86 [s, 3 H, -OC(O)CH3] ppm. 13C NMR (C6D6, 25 °C): δ =
173.3 [-OC(O)CH3], 135.0 (ipso-C6H5), 134.6 (o-C6H5), 130.3 (m-C6H5),
128.3 (p-C6H5), 21.1 [-OC(O)CH3] ppm. C14H14GeO2 (286.85): calcd. C
58.61, H 4.92; found C 58.39, H 4.85.
Experimental Section
General Considerations: All reagents were handled under an inert
atmosphere of N2 using standard Schlenk, syringe, and glovebox
techniques unless otherwise specified. Solvents were dried using a
Glass Contour solvent purification system. The compounds
nBu3GeNMe2 and nBu3GeGePh3 (2) were prepared according to the
literature procedures[43] and Ph2GeH2, nBu2GeH2, Ph6Ge2, nBu3GeCl,
and nBu3GeH were purchased from Gelest, Inc. Glacial acetic acid
was purchased from Aldrich and was used without further purifica-
nBu2Ge(H)OAc (4): A Schlenk flask was charged with nBu2GeHCl[47]
(0.40 g, 1.8 mmol) in 10 mL of benzene. The flask was wrapped
with aluminum foil and AgOAc (0.36 g, 2.2 mmol) was added to the
solution in the dark. The reaction mixture was stirred in the dark
for 48 h and then was filtered though Celite. The solvent was re-
moved in vacuo from the filtrate to yield 4 (0.38 g, 86 %) as a color-
1
tion. H and 13C NMR spectra were recorded at 400 and 100 MHz,
respectively, using a Varian UNITY INOVA 400 spectrometer. Photol-
Eur. J. Inorg. Chem. 0000, 0–0
www.eurjic.org
6
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
less oil. 1H NMR (C6D6, 25 °C): δ = 5.71 (pent, J = 3.9 Hz, 1 H, Ge-
H), 1.86 [s, 3 H, -OC(O)CH3], 1.44–1.38 (m, 4 H, -CH2CH2CH2CH3), 1.24
(sext, J = 8.0 Hz, 4 H, -CH2CH2CH2CH3), 0.81 (t, J = 7.8 Hz, 4 H,
Keywords: Germanium · Photochemistry · Mass spectrometry
-CH2CH2CH2CH3), 0.78 (t, J = 7.8 Hz, 6 H, -CH2CH2CH2CH3) ppm. 13
C
NMR (C6D6, 25 °C): δ = 173.2 [-OC(O)CH3], 26.5 [-OC(O)CH3], 24.9
(-CH2CH2CH2CH3), 15.8 (-CH2CH2CH2CH3), 13.5 (-CH2CH2CH2CH3),
1.0 (-CH2CH2CH2CH3) ppm. C10H22GeO2 (246.87): calcd. C 48.64, H
8.98; found C 48.55, H 8.87.
[1] K. M. Baines, J. A. Cooke, C. E. Dixon, H. W. Liu, M. R. Netherton, Organo-
metallics 1994, 13, 631–634.
[2] J. A. Hardwick, L. C. Pavelka, K. M. Baines, Dalton Trans. 2012, 41, 609–
621.
[3] L. A. Huck, W. J. Leigh, Can. J. Chem. 2011, 89, 241–255.
[4] K. L. Hurni, P. A. Rupar, N. C. Payne, K. M. Baines, Organometallics 2007,
26, 5569–5575.
[5] W. J. Leigh, C. R. Harrington, I. Vargas-Baca, J. Am. Chem. Soc. 2004, 126,
16105–16116.
Bu3GeOAc (5): A Schlenk flask covered with aluminum foil was
charged with nBu3GeCl (0.40 g, 1.4 mmol) in 5 mL on benzene. To
this solution was added AgOAc (0.29 g, 1.7 mmol) in the dark as a
suspension in 10 mL of benzene. The reaction mixture was stirred
in the dark for 12 h and then was filtered through Celite. The sol-
vent was evaporated from the filtrate in vacuo to yield 6 (0.41 g,
94 %) as a colorless oil. 1H NMR (C6D6, 25 °C): δ = 1.90 [s, 3 H,
-OC(O)CH3], 1.49–1.43 (m, 6 H, -CH2CH2CH2CH3), 1.30 (sext, J =
[6] W. J. Leigh, G. D. Potter, L. A. Huck, A. Bhattacharya, Organometallics
2008, 27, 5948–5959.
[7] K. Mochida, Main Group Met. Chem. 1994, 17, 25–31.
[8] K. Mochida, H. Chiba, J. Organomet. Chem. 1994, 473, 45–54.
[9] K. Mochida, H. Chiba, M. Okano, Chem. Lett. 1991, 109–112.
[10] K. Mochida, K. Kimijima, H. Chiba, M. Wakasa, H. Hayashi, Organometallics
1994, 13, 404–406.
8.0 Hz,
6 H, -CH2CH2CH2CH3), 1.14 (t, J = 8.0 Hz, 6 H,
-CH2CH2CH2CH3), 0.88 (t, J = 8.0 Hz, 9 H, -CH2CH2CH2CH3) ppm. 13
C
NMR (C6D6, 25 °C): δ = 173.0 [-OC(O)CH3], 26.1 [-OC(O)CH3], 21.7
(-CH2CH2CH2CH3), 16.0 (-CH2CH2CH2CH3), 13.5 (-CH2CH2CH2CH3),
1.0 (-CH2CH2CH2CH3) ppm. C14H30GeO2 (302.98): calcd. C 55.49, H
9.98; found C 55.31; H, 9.86.
[11] K. Mochida, S.-s. Nagano, H. Kawata, M. Wakasa, H. Hayashi, J. Orga-
nomet. Chem. 1997, 542, 75–79.
[12] K. Mochida, J. Ohto, M. Masuda, M. Nanjo, H. Arii, Y. Nakadaira, Chem.
Lett. 2008, 37, 20–21.
[13] T. Tsumuraya, Y. Kabe, W. Ando, J. Organomet. Chem. 1994, 482, 131–
138.
[14] B. Valentin, A. Castel, P. Riviere, M. Mauzac, M. Onyszchuk, A. M. Lebuis,
Heteroat. Chem. 1999, 10, 125–132.
[15] K. R. Pichaandi, J. T. Mague, M. J. Fink, J. Organomet. Chem. 2015, 791,
163–168.
[16] A. G. Moiseev, E. Coulais, W. J. Leigh, Chem. Eur. J. 2009, 15, 8485–8491.
[17] A. G. Moiseev, W. J. Leigh, Organometallics 2007, 26, 6277–6289.
[18] T. Sanji, H. Mitsugi, M. Tanaka, H. Fujiyama, H. Sakurai, Organometallics
2006, 25, 6159–6161.
Photolysis of nBu3GeGePh2GenBu3 (1) in THF Solution: A
100 mL quartz reaction flask was charged with a solution of 1
(0.300 mg, 0.420 mmol) in THF (15 mL). Glacial acetic acid (0.75 mL,
0.79 g, 13.1 mmol) was added to the reaction mixture via syringe
and the resulting solution was irradiated with UV-C light for 18 h
under an atmosphere of nitrogen. The volatiles were removed in
vacuo, the resulting colorless oil was dissolved in benzene (15 mL),
and the solution was washed with water (2 × 10 mL) to remove
excess acetic acid. The benzene layer was dried with anhydrous
MgSO4, filtered, and the solvent was removed in vacuo to yield a
thick oil.
[19] H. K. Sharma, F. Cervantes-Lee, K. H. Pannell, Organometallics 2006, 25,
3969–3973.
[20] T. Tanaka, M. Ichinohe, A. Sekiguchi, Chem. Lett. 2004, 33, 1420–1421.
[21] M. Kira, T. Iwamoto, T. Maruyama, T. Kuzuguchi, D. Yin, C. Kabuto, H.
Sakurai, J. Chem. Soc., Dalton Trans. 2002, 1539–1544.
[22] Y. Zhang, F. Cervantes-Lee, K. H. Pannell, J. Organomet. Chem. 2001, 634,
102–108.
[23] S. Sharma, K. H. Pannell, Organometallics 2000, 19, 1225–1231.
[24] I. Borthwick, L. C. Baldwin, M. Sulkes, M. J. Fink, Organometallics 2000,
19, 139–146.
[25] P. P. Gaspar, A. M. Beatty, T. Chen, T. Haile, D. Lei, W. R. Winchester, J.
Braddock-Wilking, N. P. Rath, W. T. Klooster, T. F. Koetzle, S. A. Mason, A.
Albinati, Organometallics 1999, 18, 3921–3932.
[26] H. Suzuki, K. Tanaka, B. Yoshizoe, T. Yamamoto, N. Kenmotsu, S. Matuura,
T. Akabane, H. Watanabe, M. Goto, Organometallics 1998, 17, 5091–5101.
[27] S. M. Whittaker, M.-C. Brun, F. Cervantes-Lee, K. H. Pannell, J. Organomet.
Chem. 1995, 499, 247–252.
[28] G. W. Sluggett, W. J. Leigh, Organometallics 1992, 11, 3731–3736.
[29] A. J. McKinley, T. Karatsu, G. M. Wallraff, R. D. Miller, R. Sooriyakumaran,
J. Michl, Organometallics 1988, 7, 2567–2569.
[30] S. Masamune, S. Murakami, H. Tobita, D. J. Williams, J. Am. Chem. Soc.
1983, 105, 7776–7778.
[31] M. Ishikawa, S. Katayama, M. Kumada, J. Organomet. Chem. 1983, 248,
251–260.
[32] H. Sakurai, Y. Kobayashi, Y. Nakadaira, J. Organomet. Chem. 1976, 120,
C1–C5.
Photolysis of nBu3GeGePh2GenBu3 (1) in C6D12 Solution: A
quartz NMR tube was charged with 1 (0.035 g, 0.049 mmol) in
[D12]cyclohexane (0.5 mL) and glacial acetic acid (5.6 μL, 0.0059 g,
0.098 mmol) was added. The reaction mixture was irradiated with
UV-C light for 1 min intervals and the 1H NMR spectrum was re-
corded for the first ten minutes. Intervals of 2 min were then used
until a total exposure time of 30 min was reached, after which time
the sample was irradiated for 15 min intervals.
Photolysis of nBu3GeGePh3 (2) in THF Solution: A 100 mL quartz
reaction flask was charged with a solution of 2 (0.375 mg,
0.684 mmol) in THF (20 mL). Glacial acetic acid (0.59 mL, 0.615 g,
6.55 mmol) was added to the reaction mixture via syringe and the
resulting solution was irradiated with UV-C light for 18 h under an
atmosphere of nitrogen. The volatiles were removed in vacuo, the
resulting colorless oil was dissolved in benzene (15 mL), and the
solution was washed with water (2 × 10 mL) to remove excess acetic
acid. The benzene layer was dried with anhydrous MgSO4, filtered,
and the solvent was removed in vacuo to yield a thick oil.
Supporting Information (see footnote on the first page of this
article): 1H NMR spectra for the photolysis of 1 and 2, GC/EI-MS
spectra for the photolysis product mixtures of 1 and 2, and HRAM-
MS spectra for compounds 1–6 and the photolysis product mix-
tures of 1 and 2.
[33] K. H. Scherping, W. P. Neumann, Organometallics 1982, 1, 1017–1020.
[34] W. Ando, T. Tsumuraya, J. Chem. Soc., Chem. Commun. 1987, 1514–1515.
[35] K. M. Baines, J. A. Cooke, J. J. Vittal, J. Chem. Soc., Chem. Commun. 1992,
1484–1485.
[36] M. S. Samuel, M. C. Jennings, K. M. Baines, J. Organomet. Chem. 2001,
636, 130–137.
[37] M. S. Samuel, M. C. Jennings, K. M. Baines, Organometallics 2001, 20,
590–592.
[38] N. P. Toltl, W. J. Leigh, G. M. Kollegger, W. G. Stibbs, K. M. Baines, Organo-
metallics 1996, 15, 3732–3736.
Acknowledgments
This work was supported by a research grant from the National
Science Foundation (NSF), USA (grant number CHE-1464462)
and is gratefully acknowledged.
Eur. J. Inorg. Chem. 0000, 0–0
www.eurjic.org
7
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
[39] J. A. Hardwick, K. M. Baines, Angew. Chem. Int. Ed. 2015, 54, 6600–6603;
Angew. Chem. 2015, 127, 6700.
[45] M. L. Amadoruge, J. A. Golen, A. L. Rheingold, C. S. Weinert, Organometal-
lics 2008, 27, 1979–1984.
[40] N. Y. Tashkandi, F. Parsons, J. Guo, K. M. Baines, Angew. Chem. Int. Ed.
2015, 54, 1612–1615; Angew. Chem. 2015, 127, 1632.
[41] K. L. Fujdala, D. W. K. Gracey, E. F. Wong, K. M. Baines, Can. J. Chem. 2002,
80, 1387–1392.
[46] M. L. Amadoruge, E. K. Short, C. Moore, A. L. Rheingold, C. S. Weinert, J.
Organomet. Chem. 2010, 695, 1813–1823.
[47] J. Ohshita, Y. Toyoshima, A. Iwata, H. Tang, A. Kunai, Chem. Lett. 2001,
886–887.
[42] M. Sulkes, M. J. Fink, S. E. Gottschling, K. M. Baines, Organometallics 2002,
21, 2438–2443.
[48] T. Azemi, Y. Yokoyama, K. Mochida, J. Organomet. Chem. 2005, 690, 1588–
1593.
[43] E. Subashi, A. L. Rheingold, C. S. Weinert, Organometallics 2006, 25,
3211–3219.
[44] M. L. Amadoruge, A. G. DiPasquale, A. L. Rheingold, C. S. Weinert, J.
Organomet. Chem. 2008, 693, 1771–1778.
Received: April 11, 2016
Published Online: ■
Eur. J. Inorg. Chem. 0000, 0–0
www.eurjic.org
8
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
Oligogermanes
S. P. Komanduri, A. C. Schrick,
C. L. Feasley, C. P. Dufresne,
C. S. Weinert* ...................................... 1–9
Photodecompostion of the Oligo-
germanes nBu3GeGePh2GenBu3 and
nBu3GeGePh3: Identification of the
Photoproducts by Spectroscopic
and Spectrometric Methods
Photolysis of a trigermane and diger- these molecules to yield germanium
mane results in homolytic scission of radicals and germylenes.
the germanium–germanium bonds in
DOI: 10.1002/ejic.201600421
Eur. J. Inorg. Chem. 0000, 0–0
www.eurjic.org
9
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim