Selenium insertion into the M-C bond (M = Ga, In): Syntheses and X-ray crystal structures of [Np2In(μ-SeNp)]2, [(Me3SiCH2)2Ga(μ-SeCH2SiMe 3)]2, [(Mes)C6H7N·Ga-μ-Se]

Article abstract of DOI:10.1021/om970402o

The independent 1:1 reactions of InNp₃ (Np = CH₂CMe₃) and Ga(CH₂SiMe₃)₃ with elemental selenium resulted in the formation of novel dimeric compounds with the general formula [R₂M(μ-SeR)]₂ (M = In, R = Np (1); M = Ga, R = CH₂SiMe₃ (2)) in a nearly quantitative yield. Reaction of GaMes₃ (Mes = 2,4,6-Me₃C₆H₂) with 2 mol of elemental Se, and subsequent addition of 4-picoline (C₆H₇N), resulted in the isolation of three compounds, [(Mes)C₆H₇N·Ga-μ-Se]₂ (3), (Mes)₂C₆H₇N·GaSeMes (4), and Se₂MeS₂. Compound 3 is a selenium-bridged dimer with two two-coordinate Se atoms and two 4-picoline (C₆H₇N) molecules in the dimeric unit. In related work, reaction of InNp₃ with S₂Ph₂ afforded the dimeric compound [Np₂In(μ-SPh)]₂ (5) with elimination of NpSPh. The synthesis and characterization of 1-5, including their solid-state structures, are presented.

Full text of DOI:10.1021/om970402o

Organometallics 1997, 16, 3959-3964
3959
Selen iu m In ser tion in to th e M-C Bon d (M ) Ga , In ):
Syn th eses a n d X-r a y Cr ysta l Str u ctu r es of
[Np 2In (µ-SeNp )]2, [(Me3SiCH2)2Ga (µ-SeCH2SiMe3)]2,
[(Mes)C6H7N‚Ga -µ-Se]2, a n d (Mes)2C6H7N‚Ga SeMes (Np )
CH2C(CH3)3, Mes ) 2,4,6-Me3C6H2, C6H7N ) 4-P icolin e)
Hamid Rahbarnoohi and Richard L. Wells*
Department of Chemistry, Paul M. Gross Chemical Laboratory, Duke University,
Durham, North Carolina 27708
Louise M. Liable-Sands, Glenn P. A. Yap, and Arnold L. Rheingold
Department of Chemistry, University of Delaware, Newark, Delaware 19716
Received May 15, 1997X
The independent 1:1 reactions of InNp3 (Np ) CH2CMe3) and Ga(CH2SiMe3)3 with
elemental selenium resulted in the formation of novel dimeric compounds with the general
formula [R2M(µ-SeR)]2 (M ) In, R ) Np (1); M ) Ga, R ) CH2SiMe3 (2)) in a nearly
quantitative yield. Reaction of GaMes3 (Mes ) 2,4,6-Me3C6H2) with 2 mol of elemental Se,
and subsequent addition of 4-picoline (C6H7N), resulted in the isolation of three compounds,
[(Mes)C6H7N‚Ga-µ-Se]2 (3), (Mes)2C6H7N‚GaSeMes (4), and Se2Mes2. Compound 3 is a
selenium-bridged dimer with two two-coordinate Se atoms and two 4-picoline (C6H7N)
molecules in the dimeric unit. In related work, reaction of InNp3 with S2Ph2 afforded the
dimeric compound [Np2In(µ-SPh)]2 (5) with elimination of NpSPh. The synthesis and
characterization of 1-5, including their solid-state structures, are presented.
In tr od u ction
There are several methods of synthesizing organo-
metallic 13-16 compounds that have been previously
reported in the literature.15-18 However, there are only
a handful of fully characterized compounds for the Ga-
Se systems,19-22 whereas more examples could be found
for the Al-S and Ga-S systems.23 Herein, we report
the synthesis and characterization of five novel com-
pounds, [Np2In(µ-SeNp)]2 (Np ) CH2CMe3) (1), [(Me3-
SiCH2)2Ga(µ-SeCH2SiMe3)]2 (Mes ) 2,4,6-Me3C6H2) (2),
[(Mes)C6H7N‚Ga-µ-Se]2 (3), (Mes)2C6H7N‚GaSeMes (4),
and [Np2In(µ-SPh)]2 (5).
Unlike the chemistry of II-VI (12-16) compounds
and the structural diversity that exists in such
systems,1-7 the chemistry of III-VI (13-16) compounds
and materials is in its infancy. Semiconducting materi-
als such as GaS have been made by metal-organic
chemical vapor deposition (MOCVD) using the single-
source precursor [(tBu)GaS]4,8,9 and the cubic phase of
GaS has been found to enhance the photoluminescence
intensity of GaAs.10 Syntheses of mixed-metal chalco-
genides such as CuInE2 (E ) S, Se) from a single-source
precursor11,12 have been successful and their efficiency
as photovoltaic cells are documented.13,14
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All manipulations of air- and
moisture-sensitive materials were performed in a Vacuum
Atmospheres HE-493 Dri-Lab containing an argon atmosphere
and by general Schlenk techniques. Toluene and pentane were
distilled over Na/K alloy.
X Abstract published in Advance ACS Abstracts, August 15, 1997.
(1) Steigerwald, M. L.; Sprinkle, C. R. J . Am. Chem. Soc. 1987, 109,
7200.
(2) Ueyama, N.; Sugawara, T.; Sasaki, K.; Nakamura, A.; Ya-
mashita, S.; Wakatsuki, Y.; Yamazaki, H.; Yasuoka, N. Inorg. Chem.
1988, 27, 741.
(3) Bochmann, M.; Webb, K. J .; Hursthouse, M. B.; Mazid, M. J .
Chem. Soc., Dalton Trans. 1991, 2317.
(4) Bonasia, P. J .; Arnold, J . Inorg. Chem. 1992, 31, 2508.
(5) Malik, M. A.; Motevalli, M.; Walsh, J . R.; O’Brien, P. Organo-
metallics 1992, 11, 3136.
(6) Bochmann, M.; Bwembya, G.; Grinter, R.; Lu, J .; Webb, K. J .;
Williamson, D. J .; Hursthouse, M. B.; Mazid, M. Inorg. Chem. 1993,
32, 532.
(7) Barrie, P. J .; Clark, R. J . H.; Withnall, R.; Chung, D.-Y.; Kim,
D.-W.; Kanatzidis, M. G. Inorg. Chem. 1994, 33, 1212.
(8) MacInnes, A. N.; Power, M. B.; Barron, A. R. Chem. Mater. 1992,
4, 11.
(9) Cleaver, W. M.; Spath, M.; Hnyk, D.; McMurdo, G.; Power, M.
B.; Stuke, M.; Rankin, D. W. H.; Barron, A. R. Organometallics 1995,
14, 690.
(13) Armstrong, J . H.; Pistole, C. O.; Misra, M. S.; Kapur, V. K.;
Basol, B. M. In Space Photovo´ltaic and Technology. NASA Confrence
Publication 3121; NASA: Washington, DC, 1991; pp 19-1-19-8.
(14) Wu, Y. L.; Lin, H. Y.; Sun, C. Y.; Yank, M. H.; Hwang, H. L.
Thin Solid Films 1989, 168, 113.
(15) Coates, G. E.; Green, M. L. H.; Wade, K. Organometallic
Compounds; Butler & Tanner, Ltd.: London, 1967; Vol. 1.
(16) Comprehensive Organometallic Chemistry; Wilkinson, G., Stone,
F. G. A., Abel, E. W., Eds.; Pergamon: Oxford, 1982; Vol. 1.
(17) Tuck, D. G. In Comprehensive Organometallic Chemistry;
Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon: Oxford,
1982; Vol. 1.
(18) Mole, T.; J effrey, E. A. Organoaluminum Compounds; Elsevi-
er: Amsterdam, 1972.
(19) Power, M. B.; Ziller, J . W. p.; Tyler, A. N.; Barron, A. R.
Organometallics 1992, 11, 1055.
(10) MacInnes, A. N.; Power, M. B.; Barron, A. R.; J enkins, P. P.;
Hepp, A. F. Appl. Phys. Lett. 1993, 62, 711.
(11) Hirpo, W.; Dhingra, S.; Sutorik, A. C.; Kanatzidis, M. G. J . Am.
Chem. Soc. 1993, 115, 1597.
(20) Kumar, R.; Dick, D. G.; Ghazi, S. U.; Taghiof, M.; Heeg, M. J .;
Oliver, J . P. Organometallics 1995, 14, 1601.
(21) Uhl, W.; Gerding, R.; Hahn, I.; Pohl, S.; Saak, W. Polyhedron
1996, 15, 3987.
(12) Hirpo, W.; Dhingra, S.; Kanatzidis, M. G. J . Chem. Soc., Chem.
Commun. 1992, 557.
(22) Hoffmann, G. G.; Fischer, R. Inorg. Chem. 1989, 28, 4165.
(23) Oliver, J . P. J . Organomet. Chem. 1995, 500, 269.
S0276-7333(97)00402-0 CCC: $14.00 © 1997 American Chemical Society

3960 Organometallics, Vol. 16, No. 18, 1997
Rahbarnoohi et al.
Elemental Se, S2Ph2, and 4-picoline (NC6H7) were purchased
from Aldrich and were used as received. InNp3,24 Ga(CH2-
solution was added 1.44 mL (14.74 mmol) of 4-picoline via
syringe in ca. 10 min while stirring the solution. The solution
was then heated with a heat gun to dissolve all of the
precipitate. The flask was left undisturbed overnight at room
temperature, and the X-ray quality crystals of 3 were deposited
at the bottom of the flask. The solution was separated from
the crystals of 3, and the solution was cooled to -20 °C to
afford a powder which was identified as 4. Recrystallization
of the powder from toluene afforded the X-ray quality crystals
of 4.
Da ta for 3: Yield 0.96 g, 81% based on Se. Mp: >300 °C
(dec). Anal. Calcd (found) for C30H36Ga2N2Se2: C, 49.91
(49.88); H, 5.03 (5.15); N, 3.88 (3.92). 1H NMR (C6D6): δ 1.47
(6H, s, 4-CH3-pyridine), 2.22 (6H, s, p-Me of Mes), 3.02 (12H,
s, o-Me of Mes), 6.17 (4H, d, J H-H ) 4.2 Hz, m-H of 4-picoline),
6.92 (4H, s, m-H of Mes), 8.88 (4H, d, J H-H ) 4.5 Hz, o-H of
4-picoline). 13C{1H} NMR (C6D6): δ 20.56 (Me-pyridine), 21.27
(p-Me of Mes), 25.84 (o-Me of Mes), 125.52, 127.31, 128.56,
137.73, 146.23, 147.50 (aryl). MS (EI mode): m/e 307
([GaMes2]•+).
26
SiMe3)3,25 and GaMes3 were prepared according to the
literature methods. 1H and 13C{1H} NMR spectra were
recorded on a QE-300 spectrometer operating at 300 and 75.4
MHz, respectively. 1H and 13C{1H} NMR spectra were refer-
enced to TMS by using the residual protons or carbons of
deuterated benzene at δ 7.15 or 128 ppm, respectively, and
the upfield pentet of C7D8 at δ 2.09 ppm for the 1H NMR
spectra and δ 20.4 ppm for 13C{1H} NMR spectra. All NMR
samples were prepared in 5-mm tubes, which were septum-
sealed under argon. Melting points (uncorrected) were ob-
tained with a Thomas-Hoover Uni-melt apparatus, and cap-
illaries were flame-sealed under argon. Elemental Analyses
were performed by E + R Microanalytical Laboratory, Inc.,
Corona, NY. Mass spectral data were collected on a J EOL
J MS-SX 102A spectrometer operating in the electron ionization
mode at 20 eV. X-ray crystallographic data were obtained at
25 °C on a Siemens P4 diffractometer utilizing graphite-
monochromated Mo KR (λ ) 0.710 73 Å) radiation.
P r ep a r a tion of [Np 2In (µ-SeNp )]2 (1). Inside the Dri-Lab
a 250 mL Schlenk flask equipped with a magnetic stirbar was
charged with InNp3 (1.00 g, 3.05 mmol) and ca. 25 mL of
toluene. A 0.24 g (3.05 mmol) amount of Se was added to the
solution, and the resulting mixture was refluxed. After 30
min, all the Se was consumed and a colorless solution was
formed. The solution was allowed to reflux for 6 h to ensure
complete reaction, after which all of the volatile materials were
removed under vacuo and the resultant white residue was
dissolved in 5 mL of pentane. The X-ray quality colorless
crystals of 1 were deposited at the bottom of the flask at -30
°C. Yield: 90% based on Se. Mp: 156 °C. Anal. Calcd
(found) for C30H66In2Se2: C, 44.24 (44.47); H, 8.17 (8.31). 1H
NMR (C6D6): δ 1.35 (18H, s, Se-CH2CMe3), 1.61 (36H, s, In-
CH2CMe3), 1.85 (8H, s, In-CH2CMe3), 3.36 (4H, s, Se-CH2-
CMe3). 13C{1H} NMR (C6D6): δ 28.12 (Se-CH2CMe3), 31.09
(Se-CH2CMe3), 31.93 (In-CH2CMe3), 33.93 (In-CH2CMe3),
34.65 (Se-CH2CMe3), 36.62 (In-CH2CMe3). MS (EI mode):
m/e, 1064 ([(M + M/2) - (2Np + Me)]•+), 986 ([(M + M/2) - (2Np
Da ta for 4: Yield 1.52 g, 77% based on Se. Mp: 179 °C.
Anal. Calcd (found) for C33H40GaNSe: C, 66.13 (66.02); H, 6.73
(6.82); N, 2.34 (2.25). 1H NMR (C6D6): δ 1.47 (3H, s, 4-CH3-
pyridine), 2.10 (3H, s, p-Me of Mes-Se), 2.16 (6H, s, p-Me of
Mes-Ga), 2.39 (12H, s, o-Me of Mes-Ga), 2.53 (6H, s, o-Me of
Mes-Se), 6.16 (2H, d, J H-H ) 3.6 Hz, m-H of 4-picoline), 6.72
(2H, s, m-H of Mes-Se), 6.77 (4H, s, m-H of Mes-Ga), 8.70
(4H, b, o-H of 4-picoline). 13C{1H} NMR (C6D6): δ 20.59 (Me-
pyridine), 20.93 (p-Me of Mes-Se), 21.14 (p-Me of Mes-Ga),
25.76 (o-Me of Mes-Ga), 26.41 (o-Me of Mes-Se), 125.48,
130.96, 134.65, 136.95, 143.70, 143.32, 144.39, 144.89, 145.64,
148.55, 151.63 (aryl). MS (EI mode): m/e 666 ([M + Se]•+),
586 ([M ) C33H40GaNSe]•+), 467 ([M - Mes]•+), 398 ([Se2-
Mes2]•+), 318 ([MesSeMes]•+), 200 ([HSeMes]•+), 120 ([MesH]•+).
P r ep a r a tion of [Np 2In (µ-SP h )]2 (5). A 0.33 g (1.01 mmol)
amount of InNp3 and 0.22 g (1.01 mmol) of S2Ph2 were
combined in a Schlenk flask equipped with a magnetic stirbar.
Pentane (20 mL) was added to the mixture, and the resultant
clear solution was stirred for 12 h. The volume of pentane
was reduced to 5 mL in vacuo, and the X-ray quality colorless
crystals of 5 were deposited at the bottom of the flask at -30
°C. Yield: 89% based on InNp3. Mp: 83 °C. Anal. Calcd
(found) for C32H54In2S2: C, 52.47 (52.54); H, 7.43 (7.60). 1H
NMR (C6D6): δ 1.61 (36H, s, In-CH2CMe3), 1.85 (8H, s, In-
CH2CMe3), 7.01 (6H, m, m, p-H of Ph), 7.59 (4H, d, o-H of Ph).
13C{1H} NMR (C6D6): δ 32.71 (In-CH2CMe3), 34.90 (In-
CH2CMe3), 40.66 (In-CH2CMe3), 126.20, 128.98, 133.69, 134.14
(aryl). MS (EI mode): m/e 699 ([M - S]•+), 661 ([M - Np]•+),
366 ([M/2]•+), 295 ([M/2 - Np]•+), 258 ([InNp2]•+), 324.
+ Se + Me)]•+), 743 ([M - Np]•+), 408 ([M/2]•+), 337 ([M/2
-
Np]•+), 257 ([InNp2]•+), 114.9 ([In]•+).
P r ep a r a t ion of [(Me3SiCH2)2Ga (µ-SeCH2SiMe3)]2 (2).
Compound 2 was synthesized using a procedure similar to that
used for 1. Note: Reaction time was 24 h. Reactants: Ga-
(CH2SiMe3)3 (0.50 g, 1.51 mmol), Se (0.12 g, 1.51 mmol).
Yield: 0.67 g, 94% based on Se. Mp: 106 °C. Anal. Calcd
(found) for C24H66Ga2Se2Si6: C, 35.13 (35.19); H, 8.11 (8.07).
1H NMR: δ 0.10 (18H, s, Se-CH2SiMe3), 0.27 (36H, s, Ga-
CH2SiMe3), 0.15 (8H, s, Ga-CH2SiMe3), 1.91 (4H, s, Se-CH2-
SiMe3). 13C{1H} NMR (C6D6): δ -1.29 (Se-CH2SiMe3), 2.19
(Ga-CH2SiMe3), 2.54 (Ga-CH2SiMe3), 5.38 (Se-CH2CSiMe3).
MS (EI mode): m/e 735 ([M - CH2SiMe3]•+), 441 ([M/2]•+), 395
([M/2 - Me]•+), 323 ([SeGa(CH2SiMe3)2]•+), 244 ([Ga(CH2-
SiMe3)2]•+).
X-r a y Str u ctu r a l Solu tion a n d Refin em en t. Crystal,
data collection, and refinement parameters are given in Table
1. Suitable crystals of 1-5 were mounted in thin-walled
capillaries and temporarily sealed with silicone grease under
an argon atmosphere and then flame-sealed.
P r ep a r a tion of [(Mes)C6H7N‚Ga -µ-Se]2 (3) a n d (Mes)2-
C6H7N‚Ga SeMes (4). Inside the Dri-Lab 3.15 g (7.37 mmol)
of GaMes3 and 0.52 g (7.37 mmol) of Se were combined in a
250 mL Schlenk flask, and ca. 100 mL of toluene was added
to the mixture. The flask was removed from the Dri-Lab, and
the resultant mixture was refluxed for 24 h. After 20 min of
refluxing, the color of the solution had changed to yellow and
after 2 h all of the selenium was consumed. A second mole of
selenium (0.52 g) was added to the homogeneous light orange
solution, and the mixture was refluxed for another 24 h. At
the end of this period, a white solid had precipitated out of
the solution with the consumption of all the selenium. To this
Preliminary photographic data indicated a primitive mono-
clinic crystal system for 1, 4, and 5, an I-centered monoclinic
system for 3, and no symmetry higher than triclinic for 2. The
systematic absences in the diffraction data for 1, 4, and 5 are
uniquely consistent with the reported space groups for 1, 4,
and 5. The centrosymmetric options were chosen for 2 and 3
which yielded chemically reasonable and computationally
stable results of refinement.
The structures were solved using direct methods, completed
by subsequent difference Fourier syntheses, and refined by
full-matrix least-squares procedures. Semi-empirical ellipsoid
absorption corrections were applied to 2 and 5 but not for 1,
3, and 4 because there was less than 10% variation observed
in the ψ-scan data. The molecules of 1 and 3 are located on
an inversion center, and 2 contains two independent but
chemically equivalent molecules, each lying on an inversion
center. All non-hydrogen atoms were refined with anisotropic
displacement coefficients, and hydrogen atoms were treated
(24) Beachley, O. T., J r.; Spiegel, E. F.; Kopasz, J . P.; Rogers, R. D.
Organometallics 1989, 8, 1915.
(25) Beachley, O. T., J r.; Simmons, R. G. Inorg. Chem. 1980, 19,
1021.
(26) Beachley, O. T., J r.; Churchill, M. R.; Pazik, J . C.; Ziller, J . W.
Organometallics 1986, 5, 1814.

Selenium Insertion into the M-C Bond
Organometallics, Vol. 16, No. 18, 1997 3961
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e Refin em en t for [Np 2In (µ-SeNp )]2 (1), [(Me3SiCH2)2Ga (µ-Se(CH2SiMe3)]2
(2), [(Mes)C6H7N‚Ga -µ-Se]2 (3), (Mes)2C6H7N‚Ga SeMes (4), [Np 2In (µ-SP h ])2 (5) (Np ) CH2C(CH3)3, Mes )
2,4,6-(CH3)3C6H2)
1
2
3
4
5
empirical formula
fw
C30H66In2Se2
814.39
C24H66Ga2Se2Si6
820.67
C30H36Ga2N2Se2
721.97
C33H40GaNSe
599.34
C32H54In2S2
732.51
temp, K
233(2)
233(2)
298(2)
298(2)
237(2)
radiation (wavelength, Å) Mo KR (0.710 73)
Mo KR (0.710 73)
Mo KR (0.710 73)
Mo KR (0.710 73)
Mo KR (0.710 73)
space group
a, Å
P21/c
P1h
I2/a
I21/n
P21/c
10.241(2)
10.393(3)
18.501(4)
10.058(2)
11.506(2)
19.826(4)
82.44(1)
89.80(2)
73.49(1)
14.771(2)
13.336(1)
15.924(2)
14.080(2)
15.413(1)
14.577(1)
18.778(3)
10.050(1)
19.880(2)
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
102.25(2)
99.187(8)
108.186(8)
104.31(1)
1924.3(3)
1.406
2179.4(7)
1.251
3096.8(6)
1.549
3005.4(5)
1.325
3635.4(6)
1.338
D
calcd, g cm-3
Z
2
2
4
4
4
abs coeff cm-1
31.04
30.83
41.11
21.47
14.00
cryst dimens mm
cryst habit
q range for data
collection, deg
0.30 × 0.20 × 0.20
colorless block
2.11-21.49
0.40 × 0.25 × 0.15
colorless block
2.01-22.50
0.40 × 0.10 × 0.10
colorless rod
2.00-22.49
0.40 × 0.30 × 0.30
colorless block
2.02-22.49
0.40 × 0.40 × 0.25
colorless block
2.11-33.50
no. of rflns collected
no. of independent rflns
goodness-of-fit on F2
3014
6845
2447
4819
5985
2196 (Rint ) 0.0254) 5677 (Rint ) 0.0469) 2009 (Rint ) 0.0617) 3876 (Rint ) 0.0677) 4750 (Rint ) 0.0393)
1.173
1.498
R1 ) 0.0627
wR2 ) 0.1441
1.237
R1 ) 0.0457
wR2 ) 0.1035
1.008
R1 ) 0.0460
wR2 ) 0.0914
1.313
R1 ) 0.0397
wR2 ) 0.0939
final R indicesa [I > 2R(I)] R1 ) 0.0491
wR2 ) 0.1039
a
2
Quantity minimized ) R ) ∑∆/∑(Fo), ∆ ) -|Fo - Fc)|; R(wF2) ) ∑[w(Fo - Fc2)2]/∑[(wFo2)2]1/2
.
as idealized contributions. All software and sources of the
original orange solution at -20 °C. Inside the Dri-Lab
the orange solution was evaporated to leave an orange
residue, which was completely dissolved in pentane. The
pentane solution yielded crystals (golden blocks) which
scattering factors are contained in the SHELXTL(5.3) program
libraries.27
1
Resu lts a n d Discu ssion
were identified by H NMR and MS data to be Se2Mes2
(eq 2). The white insoluble precipitate, from which
Syn th eses. Independent reactions of InNp3 (Np )
CH2C(CH3)3) and Ga(CH2SiMe3)3 with elemental sele-
nium in a 1:1 ratio in refluxing toluene resulted in the
formation of [Np2In(µ-SeNp)]2 (1) and [(Me3SiCH2)2Ga-
(µ-Se(CH2SiMe3)]2 (2) in nearly quantitative yields (eq
1). In the formation of 1, all of the selenium is
CH
compounds 3 and 4 were isolated, could have consisted
of the large aggregate (MesGaSe)n as well as (Mes2-
GaSeMes)n, which upon addition of the base (C6H7N)
yielded the more soluble adducts (eq 2).
Compound 5 was synthesized according to eq 3 (vide
infra), with the byproduct NpSPh being identified by
GC/MS. The formation of [Np2In(µ-SPh)]2 and NpSPh
1
consumed within
elemental selenium was consumed over the course of
several hours under similar conditions.
/ h, whereas for compound 2 the
2
The reaction of GaMes3 with 2 mol of elemental Se
resulted in the formation of a precipitate which was
insoluble in toluene. We did not attempt to isolate and
characterize the white precipitate, however, upon molar
addition of the base, 4-picoline (C6H7N), to the original
reaction flask and heating the reaction mixture, all of
the precipitate was dissolved to form a homogeneous
orange solution. Leaving the flask undisturbed at room
temperature for several hours resulted in the formation
of X-ray quality crystals (colorless rods) of 3. X-ray
quality crystals (colorless blocks) of 4 were isolated from
recrystallization of a white powder obtained from the
(27) SHELXTL PC; Siemens Analytical X-ray Instruments, Inc.:
Madison, WI, 1990.

3962 Organometallics, Vol. 16, No. 18, 1997
Rahbarnoohi et al.
F igu r e 2. Molecular diagram (30% probability ellipsoids)
showing the solid-state structure and atom-numbering
scheme of [(Me3SiCH2)2Ga(µ-Se(CH2SiMe3)]2 (molecule 1)
(2). Hydrogen atoms are omitted for clarity.
F igu r e 1. Molecular diagram (30% probability ellipsoids)
showing the solid-state structure and atom-numbering
scheme of [Np2In(µ-SeNp)]2 (1).
suggest that the reaction mechanism is similar to the
reactions of InMes3 with diselenides and ditellurides
reported earlier.20,28,29
Compounds 1, 2, and 5 are extremely soluble in
pentane, whereas 3 is slightly soluble and 4 shows
better solubility in toluene. Compounds 1-5 are air
sensitive and decomposed slowly in the presence of air.
We have observed that the independent insertion
reactions of GaR3 and elemental Se are much slower
when compared to similar reactions with InR3 and
elemental Se under similar forcing conditions, keeping
in mind the similar bulk of the R groups. This behavior
is also observed by Uhl and co-workers.21 One explana-
tion might be that when we compare InR3 to GaR3 (R is
a bulky group such as mesityl or neopentyl), the bulky
substituent can offer much more protection to the
smaller Ga center making it a much more hindered
molecule and, therefore, less reactive toward Se inser-
tion.
F igu r e 3. Molecular diagram (30% probability ellipsoids)
showing the solid-state structure and atom-numbering
scheme of [(Me3SiCH2)2Ga(µ-Se(CH2SiMe3)]2 (molecule 2)
(2). Hydrogen atoms are omitted for clarity.
Sp ect r oscop ic St u d ies. The mass spectrum of 1
shows larger fragments than the dimeric unit observed
in the solid state, suggesting the existence of a larger
aggregate in the vapor phase. Compounds 1, 2, and 4
are reasonably volatile and their mass spectra show
isotope patterns that match with the calculated isotope
patterns well.
The 1H NMR spectrum of 4 shows two sharp doublets
for the ortho and meta protons on the picoline group,
whereas in compound 5 these signals are much broader,
suggesting an exchange process in solution.30 Variable-
temperature NMR studies (-85 to 80 °C) were carried
out for compounds 2, 3, and 5 but no significant changes
were observed.
St r u ct u r es of [Np 2In (µ-SeNp )]2 (1) a n d [(Me3-
SiCH2)2Ga (µ-SeCH2SiMe3)]2 (2). Thermal ellipsoid
diagrams of 1-5 are shown in Figures 1-6. Crystal
data and structure refinement for 1-5 are given in
Table 1. Selected interatomic bond distances and bond
angles for 1-5 are presented in Tables 2-6. Com-
pounds 1 and 2 have a central (MSe)2 core with the
substituent on the Se in the anti conformation, with this
F igu r e 4. Molecular diagram (30% probability ellipsoids)
showing the solid-state structure and atom-numbering
scheme of [(Mes)C6H7N‚Ga-µ-Se]2 (3). Hydrogen atoms are
omitted for clarity.
orientation of ligands presumably minimizing the steric
interaction. Both compounds possess a planar four-
membered ring and the metal centers have to quasi-
tetrahedral geometry. A planar core is found in [Mes2-
In(µ-Cl)]2;31 however, a folded conformation is reported
(28) Rahbarnoohi, H.; Kumar, R.; Heeg, M. J .; Oliver, J . P. Orga-
nometallics 1995, 14, 502.
(29) Rahbarnoohi, H.; Kumar, R.; Heeg, M. J .; Oliver, J . P. Orga-
nometallics 1995, 14, 3869.
(30) Oliver, J . P.; Kumar, R. Polyhedron 1990, 9, 409.

Selenium Insertion into the M-C Bond
Organometallics, Vol. 16, No. 18, 1997 3963
Ta ble 3. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for [(Me3SiCH2)2Ga (µ-Se(CH2SiMe3)]2
(2) (Molecu le 1 a n d 2), w ith Estim a ted Sta n d a r d
Devia tion s in P a r en th esesa
Bond Lengths
Se(1)-C(1)
Se(1)-Ga(1A)
Se(2)-Ga(2A)
Ga(1)-C(5)
Ga(1)-Se(1A)
Ga(2)-C(17)
Si(1)-C(2)
1.983(9)
2.539(2)
2.529(2)
1.959(9)
2.539(2)
1.961(9)
1.856(12)
1.880(13)
1.468(3)
Se(1)-Ga(1)
Se(2)-C(13)
Se(2)-Ga(2)
Ga(1)-C(9)
Ga(2)-C(21)
Ga(2)-Se(2A)
Si(1)-C(1)
2.523(2)
1.978(9)
2.5329(14)
1.975(9)
1.954(9)
2.529(2)
1.865(10)
1.884(14)
1.388(4)
Si(1)-C(4)
Si(1)-C(3)
N(1)-C(9)
C(15)-C(20)
F igu r e 5. Molecular diagram (30% probability ellipsoids)
showing the solid-state structure and atom-numbering
scheme of (Mes)2C6H7N‚GaSeMes (4). Hydrogen atoms are
omitted for clarity.
Bond Angles
105.3(3) C(1)-Se(1)-Ga(1A) 102.4(3)
C(1)-Se(1)-Ga(1)
Ga(1)-Se(1)-Ga(1A) 85.35(5) C(13)-Se(2)-Ga(2A) 102.9(3)
C(13)-Se(2)-Ga(2)
C(5)-Ga(1)-C(9)
C(9)-Ga(1)-Se(1)
103.5(3) Ga(2A)-Se(2)-Ga(2) 84.14(5)
125.1(5) C(5)-Ga(1)-Se(1) 107.5(3)
110.8(3) C(5)-Ga(1)-Se(1A) 106.4(3)
94.65(5)
C(21)-Ga(2)-C(17) 125.6(4) C(21)-Ga(2)-Se(2A) 109.7(3)
C(9)-Ga(1)-Se(1A) 108.1(4) Se(1)-Ga(1)-Se(1A)
C(17)-Ga(2)-Se(2A) 106.7(3) C(21)-Ga(2)-Se(2)
106.0(3)
95.86(5)
111.3(6)
108.1(7)
121.0(5)
112.2(5)
118.6(5)
C(17)-Ga(2)-Se(2)
C(2)-Si(1)-C(1)
C(1)-Si(1)-C(4)
Si(1)-C(1)-Se(1)
Si(3)-C(9)-Ga(1)
Si(5)-C(17)-Ga(2)
108.9(2) Se(2B)-Ga(2)-Se(2)
107.8(6) C(2)-Si(1)-C(4)
108.0(6) C(2)-Si(1)-C(3)
111.5(5) Si(2)-C(5)-Ga(1)
120.6(5) Si(4)-C(13)-Se(2)
118.8(4) Si(6)-C(21)-Ga(2)
a
Symmetry transformation used to generate equivalent atoms:
1A -x + 2, -y, -z + 1; 2A -x - 1, -y + 3, -z.
Ta ble 4. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for [(Mes)C6H7N‚Ga -µ-Se]2 (3), w ith
Estim a ted Sta n d a r d Devia tion s in P a r en th esesa
Bond Lengths
Se-Ga(1A)
Ga-C(12)
Ga-Se(A)
N-C(5)
2.3784(12)
1.988(7)
2.3784(12)
1.313(10)
Se-Ga
2.3872(13)
2.090(6)
1.306(10)
1.382(11)
Ga-N
N-C(1)
C(1)-C(2)
Bond Angles
F igu r e 6. Molecular diagram (30% probability ellipsoids)
showing the solid-state structure and atom-numbering
scheme of [Np2In(µ-SPh)]2 (5). Hydrogen atoms are omitted
for clarity.
Ga(A)-Se-Ga
C(12)-Ga-Se(A)
C(12)-Ga-Se
Se(A)-Ga-Se
C(1)-N-Ga
79.87(4)
120.5(2)
125.2(2)
100.13(4)
118.6(6)
121.9(8)
C(12)-Ga-N
N-Ga-Se(A)
N-Ga-Se
C(1)-N-C(5)
C(5)-N-Ga
C(3)-C(2)-C(1)
103.3(3)
104.7(2)
99.6(2)
116.8(7)
123.9(6)
122.3(9)
N-C(1)-C(2)
Ta ble 2. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for [Np 2In (µ-SeNp )]2 (1), w ith
Estim a ted Sta n d a r d Devia tion s in P a r en th esesa
a
Symmetry transformation used to generate equivalent atoms:
-x + 1, -y, -z + 1.
Bond Lengths
Ta ble 5. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for (Mes)2C6H7N‚Ga SeMes (4), w ith
Estim a ted Sta n d a r d Devia tion s in P a r en th esesa
In-C(1)
In-Se
Se-C(11)
C(1)-C(2)
2.197(11)
2.7053(14)
1.972(10)
1.50(2)
In-C(6)
In-SeA
Se-InA
C(2)-C(3)
2.198(9)
2.719(2)
2.719(2)
1.51(2)
Bond Lengths
Se-C(30)
Ga-C(15)
Ga-N
1.922(6)
2.004(5)
2.095(5)
1.347(7)
Se-Ga
2.4383(9)
2.004(6)
1.384(8)
1.500(9)
Bond Angles
Ga-C(6)
C(1)-C(2)
C(14)-C(18)
C(6)-In-C(1)
C(1)-In-Se
C(1)-In-SeA
C(11)-Se-In
In-Se-InA
134.5(4)
104.2(3)
99.9(3)
103.1(3)
85.94(4)
C(6)-In-Se
109.1(3)
107.5(4)
94.06(4)
108.1(3)
118.4(7)
C(6)-In-SeA
Se-In-SeA
N-C(23)
C(11)-Se-InA
C(2)-C(1)-In
Bond Angles
106.7(2)
C(30)-Se-Ga
C(15)-Ga-N
C(15)-Ga-Se
N-Ga-Se
C(5)-C(6)-Ga
C(14)-C(15)-Ga
C(29)-C(30)-Se
C(15)-Ga-C(6)
119.9(2)
100.0(2)
114.8(2)
122.5(5)
117.3(4)
117.6(4)
117.9(5)
a
112.5(2)
111.3(2)
94.84(14)
120.8(4)
125.7(5)
121.5(5)
C(6)-Ga-N
Symmetry transformation used to generate equivalent atoms:
C(6)-Ga-Se
-x, -y + 2, -z + 2.
C(1)-C(6)-Ga
C(10)-C(15)-Ga
C(23)-N-Ga
for [Np2In(µ-SePh)]2,32 [Mes2In(µ-I)]2,33 and Np2In(µ-
SePh)(µ-PtBu2)InNp2.34 The In-Se bond lengths in 1
(average 2.71 Å) are comparable with those seen in
[Mes2In(µ-SePh)]2 (average 2.732 Å),29 [Mes2In(µ-SeMes)]2
C(25)-C(30)-Se
(average 2.715 Å),29 [Np2In(µ-SePh)]2 (average 2.743
Å),32 [tBu2In(µ-SetBu)]2 (2.70 Å),35 and polymeric [In-
(SePh)3]∞ (average 2.78 Å)36 but longer than those
observed in polymeric [MeIn(SePh)(µ-SePh)]∞ (bridging
(31) Leman, J . T.; Barron, A. R. Organometallics 1989, 8, 2214.
(32) Beachley, O. T., J r.; Lee, J . C., J r.; Gysling, H. J .; Chao, S.-H.
L.; Churchill, M. R.; Lake, C. H. Organometallics 1992, 11, 3144.
(33) Leman, J . T.; Ziller, J . W.; Barron, A. R. Organometallics 1991,
10, 1766.
(34) Beachley, O. T., J r.; Chao, S.-H. L.; Churchill, M. R.; Lake, C.
H. Organometallics 1993, 12, 5025.
(35) Stoll, S. L.; Bott, S. G.; Barron, A. R. J . Chem. Soc., Dalton
Trans. 1997, 1315.

3964 Organometallics, Vol. 16, No. 18, 1997
Rahbarnoohi et al.
Ta ble 6. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for [Np 2In (µ-SP h )]2 (5), w ith
in 3 rather than three for 2. The Ga-Se bond length
of 2.38 Å in 3 is almost identical to the covalent radii
reported for Ga-Se (2.37 Å).43
Estim a ted Sta n d a r d Devia tion s in P a r en th esesa
Bond Lengths
Compound 4 is a simple adduct with a distorted
tetrahedral geometry around the Ga center. The Ga-
Se bond length of 2.44 Å is longer than the bond length
observed for 3 but comparable to the Ga-Se bond length
reported for [tBuGaSe]4 (2.48 Å).19 The Ga-N bond
lengths of 2.090(6) Å for 3 and 2.095(5) Å for 4 are
normal, when compared to the several Ga-N adduct
bond lengths reported in the literature.44
In(1)-C(1)
In(1)-S(2)
In(2)-C(16)
In(2)-S(2)
S(1)-C(26)
C(1)-C(2)
2.162(6)
2.618(2)
2.143(6)
2.623(2)
1.788(6)
1.518(8)
In(1)-C(6)
In(1)-S(1)
In(2)-C(11)
In(1)-S(1)
S(2)-C(36)
C(2)-C(4)
2.171(6)
2.6318(14)
2.155(6)
2.651(2)
1.783(6)
1.521(12)
Bond Angles
C(1)-In(1)-C(6)
C(6)-In(1)-S(2)
C(6)-In(1)-S(1)
131.7(2)
108.8(2)
112.4(2)
C(1)-In(1)-S(2)
C(1)-In(1)-S(1)
S(2)-In(1)-S(1)
101.2(2)
105.6(2)
87.48(5)
Str u ctu r e of [Np 2In (µ-SP h )]2 (5). Compound 5 also
has an anti conformer with a puckered core consisting
of (InS)2. This molecule possess no crystallographic
symmetry. Crystals of 5 are isomorphous with previ-
C(16)-In(2)-C(11) 136.3(3)
C(16)-In(2)-S(2) 108.1(2)
C(16)-In(2)-S(1) 103.1(2)
C(11)-In(2)-S(2)
C(11)-In(2)-S(1)
C(26)-S(1)-In(1)
In(1)-S(1)-In(2)
C(36)-S(2)-In(2)
C(2)-C(1)-In(1)
103.9(2)
107.5(2)
110.0(2)
S(2)-In(2)-S(1)
C(26)-S(1)-In(2) 106.3(2)
86.98(5)
32
ously reported dimeric compounds [Np2In(µ-SePh)]2
88.25(5) C(36)-S(2)-In(1) 110.2(2)
102.3(2)
119.2(5)
and [Np2Ga(µ-TePh)]2.45 The In-S bond distances in 5
range from 2.618(2) to 2.651(2) Å. These values are in
close agreement with the bond lengths in [Mes2In(µ-St-
Bu)]2 (average 2.62 Å),46 [Me2In(µ-SSiPh3)]3 (average
2.609Å),46 and [tBu2In(µ-StBu)]2 (2.60 Å)35 but slightly
longer than the similar bond lengths reported for [Ph2-
In(µ-SSn(C6H11)3]2 (average 2.551 Å),47 [Mes2In(µ-
SSiPh3)]2 (average 2.498 Å),46 and [Mes2In(µ-Stamyl)]2
(average 2.592 Å).46 The overall geometry around the
S atoms in 5 are also pyramidal (∑S(1) ) 304.6° and
∑S(2) ) 301.6°).
In(1)-S(2)-In(2)
C(3)-C(2)-C(4)
89.14(5)
108.5(9)
SePh 2.682 Å and terminal SePh 2.541 Å),29 [In2Se21]4-
(average 2.67 Å),37 In[SeC(SiMe3)3]3 (average 2.527Å),38
In(SeMes*)3 (Mes* ) 2,4,6-tBu3-C6H2; average 2.505
Å),39 Mes*In(SePh)2 (2.526 and 2.551 Å),40 and [TptBu2]-
InSe (Tp ) tris(pyrazolyl)hydroborate) (In-Se ) 2.376-
(1) Å).41
Only a few examples of Ga-Se bond distances are
found in the literature. For 2, the average Ga-Se bond
distance of 2.53 Å is comparable to that of [Ph2Ga(µ-
SeMe)]2 (2.51 Å)20 but slightly longer than those found
in cubane [tBuGaSe]4 (2.48 Å),19 monomeric Ga(S-
eMes*)3 (average 2.324 Å),42 [(Mes)C6H7N‚Ga-µ-Se]2 (3)
(average 2.383 Å), and (Mes)2C6H7N‚GaSeMes (4) (2.428
Å). The average M-C bond distances and exocyclic
C-M-C angles for 1 and 2 are in accordance with those
of similar structures reported in the literature.23 The
bridging Se atoms in 1 and 2 are three-coordinate and
have pyramidal geometry (∑Se ) 297.14° for 1 and ∑Se1
) 293.05° for 2).
St r u ct u r es of [(Mes)C6H 7N‚Ga -µ-Se]2 (3) a n d
(Mes)2C6H7N‚Ga SeMes (4). Compound 3 is dimeric
with the central core consisting of planar (GaSe)2. The
selenium atoms are in the bridging position and are two-
coordinate. The gallium atoms have a distorted tetra-
hedral geometry. The Ga-Se bond distance of 2.38 Å
is shorter than the Ga-Se bond distance for 2 but
similar to Ga-Se bond length in monomeric R2Ga-Se-
GaR2 (R ) CH(SiMe3)2; 2.34 Å).21 This is understand-
able since the coordination number for Se atom is two
Con clu sion
From the previously reported data in the literature
and the data gathered here, we can conclude that the
insertion of elemental selenium into the Ga-C and
In-C bonds can occur with relative ease to produce the
seleno-derivatives of these metals in good yield, if the
substituent on the metal is sufficiently bulky. However,
the insertion of more than one Se atom needs further
investigation.
Ack n ow led gm en t. We are grateful for the financial
support of this work provided by the Office of Naval
Research.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
and X-ray data collection parameters, bond distances and
angles, anisotropic thermal parameters for the non-hydrogen
atoms, and atomic coordinates and isotropic thermal param-
eters for the hydrogen atoms (27 pages). Ordering information
is given on any current masthead page.
OM970402O
(36) Annan, T.; Kumar, R.; Mabrouk, H. E.; Tuck, D. G.; Chadha,
R. K. Polyhedron 1989, 8, 865.
(37) Kanatzidis, M. G.; Dhingra, S. Inorg. Chem. 1989, 28, 2026.
(38) Wuller, S. P.; Seligson, A. L.; Mitchell, G. P.; Arnold, J . Inorg.
Chem. 1995, 34, 4854.
(39) Ruhlandt-Senge, K.; Power, P. P. Inorg. Chem. 1993, 32, 3478.
(40) Rahbarnoohi, H.; Wells, R. L.; Liable-Sands, L. M.; Rheingold,
A. L. Organometallics 1996, 15, 3898.
(43) Huheey, J . E.; Keiter, E. A.; Keiter, R. L. Inorganic Chemistry,
4th ed.; Harper and Row: New York, 1993.
(44) Downs, A. J . Chemistry of Aluminium, Gallium, Indium and
Thallium; Chapman & Hall: London, 1993.
(45) Banks, M. A.; Beachley, O. T., J r.; Gysling, H. J .; Luss, H. R.
Organometallics 1990, 9, 1979.
(46) Rahbarnoohi, H.; Taghiof, M.; Heeg, M. J .; Dick, D. G.; Oliver,
J . P. Inorg. Chem. 1994, 33, 6307.
(41) Kuchta, M. C.; Parkin, G. J . Am. Chem. Soc. 1995, 117, 12651.
(42) Ruhlandt-Senge, K.; Power, P. P. Inorg. Chem. 1991, 30, 3683.
(47) Ghazi, S. U.; Heeg, M. J .; Oliver, J . P. Inorg. Chem. 1994, 33,
4517.