Preparation of LGe(Se)OH: A germanium analogue of a selenocarboxylic acid (L = HC[(CMe)(NAr)]2, Ar = 2,6-iPr2C6H 3)

Article abstract of DOI:10.1021/om060088a

LGe(Se)OH (2) (L = HC[(CMe)(NAr)]₂, Ar = 2,6-iPr ₂C₆H₃) was obtained by oxidative addition of red selenium to LGeOH (1). Compound 2 was characterized by IR, multinuclear NMR, EI-MS, and single-crystal X-ray diffraction. Furthermore, theoretical calculations of the acid strength (pK_a) of compound 2 and LGe(S)OH were carried out by means of density functional theory (DFT).

Full text of DOI:10.1021/om060088a

2384
Organometallics 2006, 25, 2384-2387
Preparation of LGe(Se)OH: A Germanium Analogue of a
Selenocarboxylic Acid (L ) HC[(CMe)(NAr)]2, Ar ) 2,6-iPr2C6H3)
Leslie W. Pineda,‡ Vojtech Jancik,‡ Rainer B. Oswald,§ and Herbert W. Roesky*,‡
Institut fu¨r Anorganische Chemie der UniVersita¨t Go¨ttingen, Tammannstrasse 4, 37077, Go¨ttingen,
Germany, and Institut fu¨r Physikalische Chemie der UniVersita¨t Go¨ttingen, Tammannstrasse 6,
37077, Go¨ttingen, Germany
ReceiVed January 27, 2006
Scheme 1
Summary: LGe(Se)OH (2) (L ) HC[(CMe)(NAr)]2, Ar ) 2,6-
iPr2C6H3) was obtained by oxidatiVe addition of red selenium
to LGeOH (1). Compound 2 was characterized by IR, multi-
nuclear NMR, EI-MS, and single-crystal X-ray diffraction.
Furthermore, theoretical calculations of the acid strength (pKa)
of compound 2 and LGe(S)OH were carried out by means of
density functional theory (DFT).
The organic chemistry of selenium has received less attention
than that of oxygen and sulfur.6 However, studies of the
chemistry of selenocarbonyl compounds are steadily increasing,
leading to new synthetic approaches in a wide range of
applications.7 Although the existence of selenocarboxylic acids
(RCSeOH) (R ) alkyl, aryl) has been confirmed at low
temperatures, structural evidence of such species has been
elusive.8 Furthermore, LGe(Se)Cl (L ) HC[(CMe)(NAr)]2, Ar
) 2,6-iPr2C6H3, Ph) was used as a precursor to prepare LGe-
(Se)F and LGe(Se)(X) (X ) Me, nBu).9 Herein, we report the
preparation of LGe(Se)OH (2) by the reaction of 1 with
elemental selenium.
Introduction
The chemical reactivity of heavier congeners of carbenes
either as dicoordinate species or with higher coordination
numbers is well documented.1 To some extent steric and
electronic stabilization apart from a proper synthetic route is a
key factor in avoiding self-condensation and polymerization.
For instance, the N-heterocyclic silylene 1,3-di-tert-butyl-2,3-
dihydro-1H-1,2,3-diazasilol-2-ylidene in the presence of water
leads to a transient silanol, which further self-condenses to the
disiloxane.2 A rare example of a hydroxygermylene compound,
LGeOH (1) (L ) HC[(CMe)(NAr)]2, Ar ) 2,6-iPr2C6H3), was
recently synthesized and structurally characterized by our group.3
The oxidative addition reaction of sulfur to the germanium center
of 1 resulted in formation of LGe(S)OH.4 The hydrogen
abstraction from the hydroxyl group of 1 with metallocene-
dimethyl derivatives of group 4 gave heterobimetallic oxides,
LGe(µ-O)M(Me)Cp2 (M ) Zr, Hf).5
Results and Discussion
Treatment of 1 in the presence of selenium in toluene at
ambient temperature resulted in the oxidative addition of
selenium to the germanium center, affording a germanium
analogue of a selenocarboxylic acid in good yield (Scheme 1).
Compound 2 is thermally stable, decomposing above 200 °C.
Its mass spectrum shows its molecular ion peak [M+] with
calculated isotopic pattern (m/z 586). The vibrational spectrum
of 2 shows a broad absorption at 3299 cm-1 that is tentatively
assigned to the OH group. LGe(S)OH showed the OH stretching
frequency at lower wavenumber in comparison to 2 (3238
cm-1).4 In the 1H NMR spectrum of 2 the OH proton resonance
was observed at δ 2.19 ppm, which is downfield compared to
that of 1 (δ 1.54 ppm).3 However, it is shifted to high field
* To whom correspondence should be addressed. E-mail: hroesky@
gwdg.de. Fax: (+49) 551-393373.
‡ Institut fu¨r Anorganische Chemie.
§ Institut fu¨r Physikalische Chemie.
(1) For selected reviews, see: (a) Saur, I.; Garcia Alonso, S.; Barrau, J.
Appl. Organomet. Chem. 2005, 19, 418-428. (b) Ku¨hl, O. Coord. Chem.
ReV. 2004, 248, 411-427. (c) Zemlyanskii, N. N.; Borisova, I. V.; Nechaev,
M. S.; Khrustalev, V. N.; Lunin, V. V.; Antipin, M. Y.; Ustynyuk, Y. U.
Russ. Chem. Bull., Int. Ed. 2004, 53, 980-1006. (d) Weidenbruch, M. J.
Organomet. Chem. 2002, 646, 39-52. (e) Gehrhus, B.; Lappert, M. F. J.
Organomet. Chem. 2001, 617-618, 209-223. (f) Tokitoh, N.; Okazaki,
R. AdV. Organomet. Chem. 2001, 47, 121-166. (g) Haaf, M.; Schmedake,
T. A.; West, R. Acc. Chem. Res. 2000, 33, 704-714. (h) Tokitoh, N.;
Okazaki, R. Coord. Chem. ReV. 2000, 210, 251-277. (i) Okazaki, R.;
Tokitoh, N. Acc. Chem. Res. 2000, 33, 625-630. (j) Weidenbruch, M. Eur.
J. Inorg. Chem. 1999, 373-381. (k) Tokitoh, N.; Matsumoto, T.; Okazaki,
R. Bull. Chem. Soc. Jpn. 1999, 72, 1665-1684. (l) Barrau, J.; Rima, G.
Coord. Chem. ReV. 1998, 178-180, 593-622. (m) Barrau, J.; Rima, G.;
El Amraoui, T. J. Organomet. Chem. 1998, 570, 163-174. (n) Dias, H. V.
R.; Wang, Z.; Jin, W. Coord. Chem. ReV. 1998, 176, 67-86. (o) West, R.;
Denk, M. Pure Appl. Chem. 1996, 68, 785-788. (p) Neumann, W. P. Chem.
ReV. 1991, 91, 311-334.
(2) Haaf, M.; Schmiedl, A.; Schmedake, T. A.; Powell, D. R.; Millevolte,
A. J.; Denk, M.; West, R. J. Am. Chem. Soc. 1998, 120, 12714-12719.
(3) Pineda, L. W.; Jancik, V.; Roesky, H. W.; Neculai, D.; Neculai, A.
M. Angew. Chem. 2004, 116, 1443-1445; Angew. Chem., Int. Ed. 2004,
43, 1419-1421.
(4) Pineda, L. W.; Jancik, V.; Roesky, H. W.; Herbst-Irmer, R. Angew.
Chem. 2004, 116, 5650-5652; Angew. Chem., Int. Ed. 2004, 43, 5534-
5536.
(5) Pineda, L. W.; Jancik, V.; Roesky, H. W.; Herbst-Irmer, R. Inorg.
Chem. 2005, 44, 3537-3540.
(6) Guziec, F. S., Jr. In Organoselenium Chemistry; Liotta, D., Ed.;
Wiley: New York, 1987; pp 215-273. (b) Guziec, F. S., Jr. In The
Chemistry of Organic Selenium and Tellurium Compounds; Patai, S., Ed.;
Wiley: Chishester, 1987; Vol. 2, pp 277-324.
(7) (a) Murai, T.; Kato, S. Top. Curr. Chem. 2000, 208, 177-199. (b)
Kato, S.; Niyomura, O. Top. Curr. Chem. 2005, 251, 13-85. (c) Niyomura,
O.; Kato, S. Top. Curr. Chem. 2005, 251, 1-12. (d) Murai, T. Top. Curr.
Chem. 2005, 251, 247-272. (e) Fujiwara, S.; Kambe, N. Top. Curr. Chem.
2005, 251, 87-140. (f) Wirth, T. Top. Curr. Chem. 2000, 208, 1-5. (g)
Nogueira, C. W.; Zeni, G.; Rocha, J. B. Chem. ReV. 2004, 104, 6255-
6285.
(8) Kageyama, H.; Murai, T.; Kanda, T.; Kato, S. J. Am. Chem. Soc.
1994, 116, 2195-2196. (b) Kato, S.; Kawahara, Y.; Kageyama, H.; Yamada,
R.; Niyomura, O.; Murai, T.; Kanda, T. Organometallics 2002, 21, 2940-
2943.
(9) Ding, Y.; Ma, Q.; Roesky, H. W.; Uso´n, I.; Noltemeyer, M.; Schmidt,
H.-G. Dalton Trans. 2003, 1094-1098.
10.1021/om060088a CCC: $33.50 © 2006 American Chemical Society
Publication on Web 03/24/2006

Notes
Organometallics, Vol. 25, No. 9, 2006 2385
Scheme 2
(1.751(2) Å).4 A similar finding was also observed for 2, having
a Ge-N bond length of 1.914(1) Å (av), in good agreement
with that of LGe(S)OH (av 1.914(2) Å),4 as well as for that of
LGe(Se)Cl (av 1.901(2) Å) and LGe(Se)F (av 1.887(3) Å).9
The acid strength of compounds 2 and LGe(S)OH were
investigated by theoretical calculations using density functional
theory (DFT) and making use of the depicted thermodynamic
cycle (Scheme 2). The pKa value can be calculated by the
following formula:
Figure 1. Thermal ellipsoid plot of 2 showing the 50% probability
level. H atoms, except for the OH group and interstitial toluene
molecule, are omitted for clarity. Selected bond lengths [Å] and
angles [deg]: Ge(1)-O(1) 1.756(1), Ge(1)-Se(1) 2.206(1), O(1)-
H(1) 0.76(2), Ge(1)-N(1) 1.915(1), Ge(1)-N(2) 1.912(1); N(2)-
Ge(1)-N(1) 95.7(1), N(1)-Ge(1)-Se(1) 115.0(1), N(2)-Ge(1)-
Se(1) 119.2(1), O(1)-Ge(1)-N(1) 102.0(1), O(1)-Ge(1)-N(2)
99.3(1), O(1)-Ge(1)-Se(1) 121.4(1), H(1)-O(1)-Ge(1) 112.5-
(2).
∆Gaq0 ) G0(Bgas-) + ∆GsolV (B-) + G0(Hgas+) +
Gsolv0(H+) - G0(BHgas) - ∆Gsolv0(BH)
and
0
∆Gaq
pKa )
compared to that of LGe(S)OH (δ 2.30 ppm).4 The 77Se NMR
resonance of 2 (δ -439 ppm) falls within the range of
compounds exhibiting ylide-type and multiple-bond character
at the germanium-selenium linkage: [LGe(Se)Cl L ) HC-
[(CMe)(NAr)]2, Ar ) 2,6-iPr2C6H3, Ph, δ -287 ppm; LGe-
(Se)F δ -465 ppm, LGe(Se)(X), X ) Me, nBu, δ -349 ppm,
δ -297 ppm].9
2.303RT
The resulting acid strengths of 2 (pKa 38.3) and LGe(S)OH
(pKa 37.2) are weak. The pKa values are in the range of aromatic
(pKa ∼33) and aliphatic (pKa ∼48) compounds. However, when
compared with oxygen-containing organic Brønsted acids (pKa
∼15), they have weaker acid strength.12 Likewise, these pKa
values correlate well when compared with the 1H NMR
resonances of the hydroxyl moiety of both compounds. Thus,
compound LGe(S)OH can be regarded to be more acidic by
virtue of its chemical shift and acid strength (δ 2.30 ppm; pKa
37.2) when compared to those of 2 (δ 2.19 ppm; pKa 38.3).
To further investigate the bonding situation around the
germanium atom in 2 and LGe(S)OH compounds, a natural bond
order analysis (NBO)13-15 was carried out. The results of this
analysis were also interpreted in terms of the donor-acceptor
interaction.16 As can be seen from the values given in Table 1,
the Ge-S bond can be described in terms of the overlap between
a p-rich sp-hybrid at the sulfur atom and a sp2 hybrid of the
germanium atom. The Ge-O bond also involves the overlap
of two p-rich hybrids, but in this case the contribution of the
germanium atom is far smaller. The Ge-N bonds show the same
distribution. In addition, the Ge-S bond is further stabilized
by 26 kcal/mol through the interaction of antibonding orbitals
of the Ge-O and Ge-N bonds. The Ge-N bond forms part of
a delocalized system with the germanium acting as bridging
atom. In the case of compound 2 the analysis mostly differs at
the Ge-Se bond, which shows a higher contribution of the
germanium atom to the molecular orbital. The direct conse-
quence of this electron drain is visible in the hydroxyl group,
Light green crystals of 2 were grown from a toluene/hexane
solution (10:2 mL) at -20 °C for one week. Compound 2
crystallizes in the monoclinic space group C2/c with one
monomer and one molecule of toluene in the asymmetric unit.
In 2, a four-coordinate germanium atom occupies the center
position of a distorted tetrahedron, which derives from the
nitrogen atoms of the scaffold ligand, a hydroxyl group, and a
selenium atom. Compound 2 prefers a selenoxo tautomeric form
of hydrogen-bonded dimers, which derives from weak inter-
molecular hydrogen interactions (O-H‚‚‚Se; O‚‚‚Se 3.336(2)°,
H‚‚‚Se 2.61(2)°, O-H-Se 163(2)°). The structure of 2 is shown
in Figure 1. The Ge-Se bond length (2.206(1) Å) in 2 is
comparable with that reported for LGe(Se)Cl1a,9 (2.197(6) Å,
2.210 Å), LGe(Se)F (av 2.174(7) Å), LGe(Se)(nBu) (2.219(6)
Å),9 and LGe(Se)Me (2.199(1) Å).9 This is very much in line
with resonance structure contributions between a Ge-Se ylide-
type bond and multiple-bond character rather than a germanium-
selenium single bond, whose bond distances range from 2.24
to 2.77 Å.10,11 In 2 the Ge-O bond length (1.756(1) Å) remains
nearly unchanged when compared with that of LGe(S)OH
(10) For comparison of germanium-selenium bond lengths, see also:
(a) Ossig, G.; Meller, A.; Bro¨nneke C.; Mu¨ller, O.; Scha¨fer, M.; Herbst-
Irmer, R. Organometallics 1997, 16, 2116-2120. (b) Foley, S. R.;
Bensimon, C.; Richeson, D. S. J. Am. Chem. Soc. 1997, 119, 10359-10363.
(c) Matsumoto, T.; Tokitoh, N.; Okazaki, R. J. Am. Chem. Soc. 1999, 121,
8811-8824. (d) Kuchta, M.; Parkin, G. Coord. Chem. ReV. 1998, 176, 323-
372. (e) Ding, Y.; Ma, Q.; Roesky, H. W.; Herbst-Irmer, R.; Uso´n, I.;
Noltemeyer, M.; Schmidt, H.-G. Organometallics 2002, 21, 5216-5220.
(11) For shortest and longest Ge-Se single bond see: (a) Ahari, H.;
Garcia, A.; Kirkby, S.; Ozin, G. A.; Young, D.; Lough, A. J. J. Chem.
Soc., Dalton Trans. 1998, 2023-2028. (b) Karsch, H. H.; Baumgartner,
G.; Gamper, S.; Lachmann, J.; Mu¨ller, G. Chem. Ber. 1992, 125, 1333-
1339.
(12) Clayden, J.; Greeves, N.; Wothers, P. Organic Chemistry; 1st
Oxford: Oxford, U.K., 2004; pp 181-206.
(13) Foster, J. P.; Weinhold, F. J. Am. Chem. Soc. 1980, 102, 7211-
7218.
(14) Reed, A. E.; Weinhold, F. J. Chem. Phys. 1985, 83, 1736-1740.
(15) Reed, A. E.; Curtiss, L. A.; Weinhold, F. Chem. ReV. 1988, 88,
899-926.
(16) Weinhold, F.; Landis, C. Valency and Bonding; Cambridge:
University Press, U.K., 2005; pp 19, 20, 94-96, 125-128, 184-188.

2386 Organometallics, Vol. 25, No. 9, 2006
Table 1. Results of the Bonding Analysis of LGe(Ch)OH (1-S, Ch ) S; 2-Se, Ch ) Se)
Notes
occ
bond
contr (%)
MO1
type
contr (%)
MO2
type
1-S
1.912
1.965
1.932
1.932
1.985
1.903
1.966
1.933
1.933
1.985
S-Ge
61.4
16.2
15.6
15.6
75.6
58.1
16.2
15.8
15.8
75.6
S
s(16%)p 5.2(83.7%)
s(23.5%)p 3.2(76.1%)
s(21.3%)p 3.7(78.5%)
s(21.3%)p 3.7(78.5%)
s(22.8%)p3.4(77.1%)
s(14%)p 6.2(86%)
s(23.4%)p 3.3(76.3%)
s(21.4%)p 3.7(78.3%)
s(21.4%)p 3.7(78.3%)
s(22.6%)p 3.4(77.4%)
38.6
83.8
84.4
84.4
24.4
42
83.8
84.2
84.2
24.4
Ge
O
N5
N6
H
Ge
O
N5
N6
H
s(34.2%)p 1.9(65.3%)
s(26.5%)p 2.7(73.5%)
s(27.8%)p 2.6(72.2%)
s(27.8%)p 2.6(72.2%)
s(99.7%)
s(34%)p 1.9(65.4%)
s(27%)p 2.7(73%)
s(28.2%)p 2.6(71.8%)
s(28.2%)p 2.6(71.8%)
s(99.7%)
Ge-O
Ge-N5
Ge-N6
O-H
Ge
Ge
Ge
O
Se
Ge
Ge
Ge
O
2-Se
Se-Ge
Ge-O
Ge-N5
Ge-N6
O-H
compound 2 of the OH group was localized from the difference
electron density map and refined isotropically, whereas the hydrogen
atoms of C-H bonds were placed in idealized positions and refined
isotropically with a riding model. The non-hydrogen atoms were
refined anisotropically. Crystal data for compound 2‚toluene:
C36H50GeN2OSe, Mw ) 678.33, monoclinic, space group C2/c, a
) 25.974(4) Å, b ) 16.195(3) Å, c ) 18.151(3) Å, â ) 115.82-
(3)°, V ) 6873(3) Å3, Z ) 8, Fcalcd ) 1.311 g‚cm-3, F(000) )
which now shows a positive interaction with the Ge-O bond,
which was not visible in the sulfur system.
In summary, oxidative addition of selenium at the germanium
center led to LGe(Se)OH. Also the first assessment of the acid
strength of this new class of carbon-free carbonic acids based
on germanium was carried out by density functional calculations.
Experimental Section
2832, λ ) 1.54178 Å, T ) 100(2) K, µ(Cu KR) ) 1.593 mm-1
.
General Comments. All experimental manipulations were
carried out under an atmosphere of dry nitrogen using standard
Schlenk techniques. The samples for spectral measurements were
prepared in a drybox. The solvents were purified according to
conventional procedures and were freshly distilled prior to use. Red
amorphous selenium was prepared according to the literature
procedure.17 NMR spectra were recorded on a Bruker Avance 500
Of the 14 278 measured reflections, 4734 were independent [R(int)
) 0.0210]. The final refinements converged at R1 ) 0.0238 for I
> 2σ(I), wR2 ) 0.0620 for all data. The final difference Fourier
synthesis gave a min./max. residual electron density 0.391/-0.300
e‚Å-3
.
Computational and Calculations Details. For all calculations
the well-established DFT variant B3LYP method was used.20,21 The
computations were carried out with the Gaussian G0322 program
suite employing a modified 6-31G basis set extended with additional
diffuse functions.23,24 In the first step all molecules were fully
optimized to their equilibrium structures. The resulting structures
were in good agreement with the crystallographic data. To avoid
the recourse to experimental data as much as possible, only the
values for the proton have been taken from references.25,26 The ab
initio values for the energy of solvation (A,C) have been calculated
with a modification of the polarizable continuum model (PCM)
termed IEFPCM.27
1
instrument, and the H, 13C, and 77Se chemical shifts are reported
with reference to tetramethylsilane (TMS) and dimethylselenide
(Me2Se), respectively. IR spectra were recorded on a Bio-Rad
Digilab FTS-7 spectrometer. Mass spectra were obtained on a
Finnigan MAT 8230 spectrometer by EI technique. Melting points
were obtained in sealed capillaries on a Bu¨chi B 540 instrument.
CHN analyses were performed at the Analytical Laboratory of the
Institut fu¨r Anorganische Chemie der Universita¨t Go¨ttingen,
Germany.
Preparation of LGe(Se)OH (2). To a suspension of elemental
red selenium (0.29 g, 3. 67 mmol) in toluene (20 mL) was added
via cannula a solution of 1 (1.86 g, 3.67 mmol) in toluene (30 mL).
A pale green solution appeared after 30 min, which finally remained
unchanged after 18 h of stirring. Subsequent filtration and solvent
removal gave a pale green solid, which was washed twice with
cold pentane (2 × 10 mL). Yield: 1.66 g (77%). Mp: 220 °C dec.
IR (KBr pellet): ν˜ ) 3292 br (OH) cm-1. 1H NMR (500.13 MHz,
C6D6, 25 °C, TMS): δ 7.09-7.16 (m, 6H; m-, p-Ar-H), 4.85 (s,
1H; γ-CH), 3.65 (sept, 2H, 3JH-H ) 6.8 Hz; CH(CH3)2), 3.29 (sept,
(18) SHELXS-97, Program for Structure Solution. Sheldrick, G. M. Acta
Crystallogr. Sect. A 1990, 46, 467-473.
(19) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure
Refinement; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(20) Lee, C.; Yang, W.; Parr, R. G. Phys. ReV. B 1988, 37, 785-789.
(21) Miehlich, B.; Savin, A.; Stoll, H.; Preuss, H. Chem. Phys. Lett. 1989,
157, 200-206.
(22) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb,
M. A.; Cheeseman, J. R.; Montgomery, Jr., J. A.; Vreven, T.; Kudin, K.
N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.;
Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.;
Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.;
Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li,
X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken, V.; Adamo, C.;
Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.;
Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.;
Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich,
S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A.
D.; Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A.
G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.;
Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham,
M. A.; Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.;
Johnson, B.; Chen, W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian
03, Revision C.02; Gaussian, Inc: Wallingford, CT, 2004.
(23) Petersson, G. A.; Al-Laham, M. A. J. Chem. Phys. 1991, 94, 6081-
6090.
(24) Petersson, G. A.; Bennett, A.; Tensfeldt, T. G.; Al-Laham, M. A.;
Shirley, W. A.; Mantzaris, J. J. Chem. Phys. 1988, 89, 2193-2218.
(25) Liptak, M. D.; Cross, K. C.; Seybold, P. G.; Feldgus, S.; Shields,
G. C. J. Am. Soc. 2002, 124, 6421-6427.
(26) Magill, A. M.; Cavell, K. J.; Yates, B. F. J. Am. Chem. Soc. 2004,
126, 8717-8724.
(27) Cance`s, E.; Mennucci, B.; Tomasi, J. J. Chem. Phys. 1997, 107,
3032-3041.
3
2H, JH-H ) 6.8 Hz; CH(CH3)2), 2.19 (s, 1H; OH), 1.56 (d, 6H,
3JH-H ) 6.8 Hz; CH(CH3)2), 1.48 (s, 6H; CH3), 1.30 (d, 6H, 3JH-H
3
) 6.8 Hz; CH(CH3)2), 1.17 (d, 6H, JH-H ) 6.8 Hz; CH(CH3)2),
3
1.04 ppm (d, 6H, JH-H ) 6.8 Hz; CH(CH3)2). 13C NMR (125.75
MHz, C6D6, 25 °C, TMS): δ 169.6 (CN), 146.0, 144.7, 137.4,
129.0, 124.9, 124.7 (i-, o-, m-, p-Ar), 99.0 (γ-CH), 29.7 (CH3),
28.0 (CH(CH3)2), 26.4 (CH(CH3)2), 24.7 (CH(CH3)2), 24.6 (CH-
(CH3)2), 24.0 (CH(CH3)2), 23.8 ppm (CH(CH3)2). 77Se NMR (95.38
MHz, C6D6, 25 °C, Me2Se): δ -439.8 ppm. EI-MS (70 eV): [m/z
(%)] 586 (35) [M+], 571 (15) [M+ - Me], 553 (15) [M+ - MeOH],
507 (15) [M+ - Se]. Anal. Calcd for C29H42GeN2OSe (586.22):
C, 59.42; H, 7.22; N, 4.78. Found: C, 59.18; H, 7.24; N, 4.66.
Molecular Structure Determination. Data for the structure of
2 was collected on a Bruker three-circle diffractometer equipped
with a SMART 6000 CCD detector with monochromated Cu KR
radiation (λ ) 1.54178 Å). Intensity measurements were performed
on a rapidly cooled crystal using ω scans. The structures were
solved by direct methods (SHELXS-97)18 and refined with all data
by full-matrix least squares on F2.19 The hydrogen atom of
(17) Meyer, J. Ber. 1913, 46, 3089-3091.

Notes
Acknowledgment. We thank the Go¨ttinger Akademie der
Wissenschaften and the Fonds der Chemischen Industrie for
support. L.W.P. thanks the Deutscher Akademischer Aus-
tauschdienst (DAAD) for a predoctoral fellowship.
Organometallics, Vol. 25, No. 9, 2006 2387
Supporting Information Available: X-ray data (CIF) for 2.
This material is available free of charge via the Internet at
http://pubs.acs.org.
OM060088A