Lewis base character of hydroxygermylenes for the preparation of heterobimetallic LGe(OH)M systems (M = Fe, Mn, L = HC[(CMe)(NAr)]2, Ar = 2,6-iPr2C6H3)

Article abstract of DOI:10.1021/om0600893

LGeOH (1; L = HC[(CMe)(NAr)]₂, Ar = 2,6-iPr₂C ₆H₃) reacted with iron and manganese complexes to give LGe(OH)Fe(CO)₄ (2) and LGe(OH)Mn(Cp)(CO)₂ (3; Cp = cyclopentadienyl). Compounds 2 and 3

Full text of DOI:10.1021/om0600893

Organometallics 2006, 25, 2381-2383
2381
Lewis Base Character of Hydroxygermylenes for the Preparation of
Heterobimetallic LGe(OH)M Systems (M ) Fe, Mn, L )
HC[(CMe)(NAr)]2, Ar ) 2,6-iPr2C6H3)
Leslie W. Pineda,† Vojtech Jancik,† Juan F. Colunga-Valladares,‡ Herbert W. Roesky,*,†
Anja Hofmeister,† and Jo¨rg Magull†
Institut fu¨r Anorganische Chemie der UniVersita¨t Go¨ttingen, Tammannstrasse 4,
37077 Go¨ttingen, Germany, and Institut fu¨r Organische und Biomolekulare Chemie der UniVersita¨t
Go¨ttingen, Tammannstrasse 2, 37077 Go¨ttingen, Germany
ReceiVed January 27, 2006
Scheme 1
Summary: LGeOH (1; L ) HC[(CMe)(NAr)]2, Ar ) 2,6-
iPr2C6H3) reacted with iron and manganese complexes to giVe
LGe(OH)Fe(CO)4 (2) and LGe(OH)Mn(Cp)(CO)2 (3; Cp )
cyclopentadienyl). Compounds 2 and 3 were characterized by
IR, multinuclear NMR, EI-MS, and single-crystal X-ray dif-
fraction.
Introduction
Scheme 2
The preparation of compounds with bonds between a transi-
tion metal and silicon, germanium, tin, or lead has provided a
rich chemistry, including synthetic and structural aspects as well
as catalytic applications.1 Furthermore, the investigation of the
reactivity of divalent heavier group 14 elements has prompted
a constant interest, due to the wide range of reaction possibili-
ties.2 The presence of bulky ligands and complexation with
transition metals have greatly increased the stability of otherwise
unstable species. In this regard, a compound of the composition
ArGeOH‚W(CO)5 was obtained by hydrolysis of ArGeNR2‚
W(CO)5 (Ar ) 2,6-bis((diethylamino)methyl)phenyl; R ) iPr).3
In some cases such low-valent group 14 compounds, by virtue
of the electron lone pair, function as Lewis bases toward
coordinatively unsaturated transition metals.4 Recently, we
reported the isolation and structural characterization of LGeOH
(1; L ) HC[(CMe)(NAr)]2, Ar ) 2,6-iPr2C6H3), which may
either act as a donor or react at the OH functionality with
transition metals.5 The latter mode of reaction is reminiscent
of a water-gas shift reaction.6 Herein, we report the reaction of
1 with iron and manganese carbonyl complexes and their
characterization by IR, mass spectrometry, multinuclear spec-
troscopy, and single-crystal X-ray structural analysis.
* To whom correspondence should be addressed. E-mail:
hroesky@gwdg.de. Fax: (+49) 551-393373.
† Institut fu¨r Anorganische Chemie.
‡ Institut fu¨r Organische und Biomolekulare Chemie.
(1) (a) Mackay, K. M.; Nicholson, B. K. In ComprehensiVe Organome-
tallic Chemistry; Wilkinson, G., Ed.; Pergamon: Oxford, U.K., 1982; pp
1043-1114. (b) Petz, W. Chem. ReV. 1986, 86, 1019-1047. (c) Wagner,
H.; Baumgartner, J.; Marschner, C. Organometallics 2005, 24, 4649-4653.
(d) Holt, M. S.; Wilson, W. L.; Nelson, J. H. Chem. ReV. 1989, 89, 11-49.
(e) Filippou, A. C.; Rohde, H.; Schnakenburg, G. Angew. Chem. 2004, 116,
2293-2297; Angew. Chem., Int. Ed. 2004, 43, 2243-2247. (f) Filippou,
A. C.; Portius, P.; Philippopoulos, A. I.; Rohde, H. Angew. Chem. 2003,
115, 461-464; Angew. Chem., Int. Ed. 2003, 42, 445-447. (g) Filippou,
A. C.; Philippopoulos, A. I.; Schnakenburg, G. Organometallics 2003, 22,
3339-3341. (h) Okazaki, M.; Tobita, H.; Ogino, H. Dalton Trans. 2003,
493-506. (i) Adams, R. D.; Captain, B.; Fu, W. Inorg. Chem. 2003, 42,
1328-1333. (j) Adams, R. D.; Captain, B.; Fu, W.; Smith, M. D. Inorg.
Chem. 2002, 41, 5593-5601. (k) Filippou, A. C.; Portius, P.; Philippopoulos,
A. I. Organometallics 2002, 21, 653-661. (l) Filippou, A. C.; Philippopou-
los, A. I.; Portius, P.; Neumann, D. U. Angew. Chem. 2000, 112, 2881-
2884; Angew. Chem., Int. Ed. 2000, 39, 2778-2781. (m) Agustin, D.; Rima,
G.; Gornitzka, H.; Barrau, J. Eur. J. Inorg. Chem. 2000, 693-702. (n)
Agustin, D.; Rima, G.; Gornitzka, H.; Barrau, J. Inorg. Chem. 2000, 39,
5492-5495. (o) Simons, R. S.; Power, P. P. J. Am. Chem. Soc. 1996, 118,
11966-11967.
Results and Discussion
Compounds 2 and 3 were obtained by reaction of 1 with the
respective transition-metal fragments. Compound 2 was isolated
after separation of Fe(CO)5, also a product of the reaction of 1
and diiron nonacarbonyl, as a light brown powder (Scheme 1).
Compound 3 was prepared by the reaction of 1 with
cyclopentadienylmanganese tricarbonyl with concomitant CO
elimination during 3 h of UV irradiation in THF at ambient
temperature (Scheme 2). Compounds 2 and 3 are air- and
moisture-sensitive. 2 is soluble in THF, sparingly soluble in
toluene, and insoluble in common organic solvents, whereas 3
is insoluble in the aforementioned solvents and in DMSO as
well. 2 and 3 are thermally quite stable, and their mass spectra
show the molecular ion peaks [M+] with proper isotopic patterns
(2) (a) Gehrhus, B.; Lappert, M. F. J. Organomet. Chem. 2001, 617-
618, 209-223. (b) Haaf, M.; Schmedake, T. A.; West, R. Acc. Chem. Res.
2000, 33, 704-714. (c) Barrau, J.; Rima, G. Coord. Chem. ReV. 1998, 178-
180, 593-622. (d) Neumann, W. P. Chem. ReV. 1991, 91, 311-334. (e)
West, R.; Denk, M. Pure Appl. Chem. 1996, 68, 785-788. (f) Okazaki,
R.; Tokitoh, N. Acc. Chem. Res. 2000, 33, 625-630.
(4) (a) Lappert, M. F.; Rowe, R. S. Coord. Chem. ReV. 1990, 100, 267-
292. (b) Lappert, M. F.; Power, P. P. J. Chem. Soc., Dalton Trans. 1985,
51-57. (c) Jutzi, P.; Steiner, W. Chem. Ber. 1976, 109, 3473-3479.
(5) 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.
(3) Bibal, C.; Mazie`res, S.; Gornitzka, H.; Couret, C. Organometallics
2002, 21, 2940-2943.
(6) Ford, P. C. Acc. Chem. Res. 1981, 14, 31-37.
10.1021/om0600893 CCC: $33.50 © 2006 American Chemical Society
Publication on Web 03/25/2006

2382 Organometallics, Vol. 25, No. 9, 2006
Notes
Figure 2. Thermal ellipsoid plot of 3 with ellipsoids at the 50%
probability level. H atoms, except for the OH group, are omitted
for clarity. Selected bond lengths (Å) and angles (deg): Ge(1)-
O(1) ) 1.816(2), Ge(1)-N(2) ) 1.970(2), Ge(1)-N(1) ) 1.963(2),
Mn(1)-Ge(1) ) 2.345(1), O(2)-C(30) ) 1.187(3), O(3)-C(31)
) 1.165(4), Mn(1)-C(30) ) 1.744(3), Mn(1)-C(31) ) 1.772(3);
O(1)-Ge(1)-N(2) ) 93.7(1), O(1)-Ge(1)-N(1) ) 93.4(1), N(1)-
Ge(1)-N(2) ) 91.1(1), O(1)-Ge(1)-Mn(1) ) 119.0(1), N(1)-
Ge(1)-Mn(1) ) 123.5(1), N(2)-Ge(1)-Mn(1) ) 127.4(1), C(30)-
Figure 1. Thermal ellipsoid plot of 2 with ellipsoids at the 50%
probability level. H atoms, except for the OH group, are omitted
for clarity. Selected bond lengths (Å) and angles (deg): Ge(1)-
O(1) ) 1.840(2), Ge(1)-N(1) ) 1.945(2), Ge(1)-N(2) ) 1.948(2),
Fe(1)-Ge(1) ) 2.330(1), Fe(1)-C(30) ) 1.772(3), Fe(1)-C(31)
) 1.796(3), Fe(1)-C(32) ) 1.795(4), Fe(1)-C(33) ) 1.782(3);
O(1)-Ge(1)-N(1) ) 98.3(1), O(1)-Ge(1)-N(2) ) 98.8(1), N(1)-
Ge(1)-N(2) ) 93.2(1), O(1)-Ge(1)-Fe(1) ) 113.5(1), N(2)-
Ge(1)-Fe(1) ) 123.3(1), N(1)-Ge(1)-Fe(1) ) 124.3(1), C(30)-
Fe(1)-C(33) ) 91.6(1), C(30)-Fe(1)-C(32) ) 88.6(1), C(33)-
Fe(1)-C(32) ) 116.9(2), C(30)-Fe(1)-C(31) ) 86.8(1), C(33)-
Fe(1)-C(31) ) 124.7(2), C(32)-Fe(1)-C(31) ) 118.3(1), C(30)-
Fe(1)-Ge(1) ) 175.8(1), C(33)-Fe(1)-Ge(1) ) 85.1(1), C(32)-
Fe(1)-Ge(1) ) 95.2(1), C(31)-Fe(1)-Ge(1) ) 93.0(1).
Mn(1)-Ge(1) ) 87.6(1), C(31)-Mn(1)-Ge(1) ) 95.0(1); X1A
-
Mn(1) ) 1.779(3), X1A-Mn(1)-Ge(1) ) 128.9(3), X1A-Mn(1)-
C(30) ) 123.8(3), X1A-Mn(1)-C(31) ) 120.7(3). X1A ) centroid
of the Cp ring.
that in [{η3-[(µ-tBuN)2(SiMeNtBu)2]}GeFe(CO)4] (2.348(1) Å)9
but is slightly longer in comparison with that in L′Ge(Cl)Fe-
(CO)4 (2.298(2) Å; L′ ) HC[(CMe)(NPh)]2)8 and is clearly
shortened (2.240(2) Å) in [Fe(CO)4{Ge(OC6H2tBu2-2,6-Me-
4)2}].10 Moreover, a longer Ge-O bond length in 2 (1.840(2)
Å) is observed compared with that in LGeOH (1.828(1) Å).5
This is in contrast with the shortened Ge-O bond length found
in LGe(S)OH (1.751(2) Å; L ) HC[(CMe)(NAr)]2, Ar ) 2,6-
iPr2C6H3).11
(m/z 676 and 684, respectively), followed by stepwise elimina-
tion of CO. 3 displays a very sharp OH band in the IR spectrum
(ν˜ 3642 cm-1). The corresponding absorption for 2 was found
at lower wavenumber (ν˜ 3599 (OH) cm-1). These values are in
agreement with the OH frequency reported for ArGeOH‚
W(CO)5 (ν˜ 3645 cm-1; Ar ) 2,6-bis((diethylamino)methyl)-
phenyl, R ) iPr).3 Moreover, carbonyl absorptions for 2 and 3
In 3 both the germanium and the manganese atom reside in
the center of a distorted-tetrahedral environment, where ger-
manium is bonded to a â-diketiminato ligand, to a hydroxyl
group, and to a manganese atom, while the coordination sphere
around the manganese atom comprises two carbonyl groups and
a cyclopentadienyl ligand (Figure 2). Previously reported
germanium-manganese complexes such as [(η5-MeC5H4)Mn-
(CO)2]3Ge and [(η5-MeC5H4)Mn(CO)2]3Ge have Ge-Mn bond
lengths between 2.236(1) and 2.573(1) Å and are in the same
range as found in 3 (2.345(1) Å).12 Further structural analysis
of 3 shows that the Ge-O bond length (1.816(2) Å) is
unchanged with respect to that in 2 and displays an OH
orientation pointing toward the transition-metal center, in
contrast to the case for 2, where it is pointing toward the C3N2-
Ge backbone.
were found at ν˜ 2039, 1956, 1942 cm-1 and at 1864, 1846 cm-1
,
respectively: these are in the expected range for terminal
carbonyl groups.7
The 1H NMR spectrum of 2 in d8-THF revealed a downfield
(δ 4.24 ppm) resonance of the hydroxyl proton. The CO
resonance in the 13C NMR spectrum was found at δ 214.8 ppm,
a value comparable to that of LGe(Cl)Fe(CO)4 (δ 213.1 ppm).8
Due to the poor solubility of 3, analogous measurements could
not be carried out. The molecular structures of 2 and 3 were
determined by single-crystal X-ray analyses. 2 and 3, respec-
tively, were dissolved in hot toluene, and after the solution was
cooled to ambient temperature, single crystals were obtained.
2 formed light brown crystals and 3 light orange-yellow crystals.
Both compounds crystallize in the monoclinic space group P21/
n. In 2, a germanium atom binds to a monoanionic â-diketimi-
nato ligand, to a hydroxyl group, and to an iron-carbonyl
fragment, generating a four-coordinate germanium center, which
adopts a distorted-tetrahedral geometry. Also, one can argue
that germanium takes up the axial position of a distorted-
trigonal-bipyramidal geometry at the Fe(CO)4 fragment (Figure
1). The Ge-Fe bond length in 2 (2.330(1) Å) is comparable to
(9) Veith, M.; Becker, S.; Huch, V. Angew. Chem. 1990, 102, 186-
188; Angew. Chem., Int. Ed. Engl. 1990, 29, 216-218.
(10) Hitchcock, P. B.; Lappert, M. F.; Thomas, S. A.; Thorne, A. J. J.
Organomet. Chem. 1986, 315, 27-44.
(11) 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.
(12) Ga¨de, W.; Weiss, E. J. Organomet. Chem. 1981, 213, 451-460.
For comparison on germanium-manganese bond distances, see also: (a)
Melzer, D.; Weiss, E. J. Organomet. Chem. 1984, 263, 67-73. (b) Leung,
W.-P.; So, C.-W.; Kan, K.-W.; Chan, H.-S.; Mak, T. C. W. Inorg. Chem.
2005, 44, 7286-7288. (c) Lei, D.; Hampden-Smith, M. J.; Duesler, E. N.;
Huffman, J. C. Inorg. Chem. 1990, 29, 795-798.
(7) Shriver, D. F.; Atkins, P. W. Inorganic Chemistry, 3rd ed.; Oxford
University Press: Oxford, U.K., 1999; pp 544-549.
(8) Saur, I.; Rima, G.; Miqueu, K.; Gornitzka, H.; Barrau, J. J.
Organomet. Chem. 2003, 672, 77-85.

Notes
Organometallics, Vol. 25, No. 9, 2006 2383
Stirring was continued for 2 h; the solvent was removed in vacuo,
and the resulting orange-yellow residue was rinsed with pentane
(2 × 20 mL). Recrystallization of 3 was accomplished by gently
heating a toluene solution. From the solution at ambient temperature
orange-yellow crystals were obtained on standing overnight.
Yield: 0.51 g (76%). Mp: 265 °C dec. IR (KBr pellet): ν˜ 3642 s
(OH), 1921 s, 1864 w, 1846 s (CO) cm-1. EI-MS (70 eV; m/z
(%)): 684 (5) [M+], 610 (10) [M+ - 2CO - OH], 491 (100) [M+
- 2CO - Cp - Mn - OH]. Anal. Calcd for C36H47GeMnN2O3
(684.22): C, 63.14; H, 6.92; N, 4.10. Found: C, 63.25; H, 6.95;
N, 4.18.
Conclusion
The reactivity of the LGeOH compound with an electron lone
pair and an OH moiety was demonstrated by the reaction with
transition-metal fragments of manganese and iron, respectively.
Experimental Section
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.
Diiron nonacarbonyl was purchased from Aldrich and manganese
cyclopentadienyltricarbonyl from Strem Chemicals, and both
compounds were used as received. NMR spectra were recorded on
a Bruker Avance 500 instrument, and the 1H and 13C chemical shifts
are reported with reference to tetramethylsilane (TMS). Irradiation
was carried out at ambient temperature using a low-pressure
immersion lamp in a quartz reaction tube. IR spectra were recorded
on a Bio-Rad Digilab FTS-7 spectrometer. Mass spectra were
obtained on a Finnigan MAT 8230 spectrometer by EI techniques.
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, Go¨ttingen, Germany.
Molecular Structure Determination. Data for 2 and 3 were
collected on a Stoe IPDS II-array detector system instrument with
graphite-monochromated Mo KR radiation (λ ) 0.71073 Å).
Intensity measurements were performed on a rapidly cooled crystal
using ω scans. The structures were solved by direct methods
(SHELXS-97)13 and refined with all data by full-matrix least squares
on F2.14 The hydrogen atoms of structures 2 and 3 of the OH groups
were localized from the difference electron density maps 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 2: C33H42FeGeN2O5, Mw ) 675.13, monoclinic,
space group P21/n, a ) 16.004(1) Å, b ) 9.874(1) Å, c ) 20.379(1)
Å, â ) 96.42(1)°, V ) 3200(1) Å3, Z ) 4, Fcalcd ) 1.401 g cm-3
,
F(000) ) 1408, λ ) 0.710 73 Å, T ) 133(2) K, µ(Mo KR) )
1.435 mm-1. Of the 19 288 measured reflections, 5445 were
independent (R(int) ) 0.0614). The final refinements converged at
R1 ) 0.0501 for I > 2σ(I) and wR2 ) 0.0643 for all data. The
final difference Fourier synthesis gave a minimum/maximum
residual electron density of +0.348/-0.254 e Å-3. Crystal data for
3: C36H47GeMnN2O3, Mw ) 683.29, monoclinic, space group P21/
n, a ) 10.705(1) Å, b ) 20.487(1) Å, c ) 15.160(1) Å, â )
98.02(1)°, V ) 3292(1) Å3, Z ) 4, Fcalcd ) 1.378 g cm-3, F(000)
Preparation of LGe(OH)Fe(CO)4 (2). A flask was charged with
1 (1.99 g, 3.93 mmol) and Fe2(CO)9 (1.42 g, 3.93 mmol) in THF
(40 mL). The solution was stirred overnight at ambient temperature.
The byproduct was removed by filtration over Celite, resulting in
a clear pale brown filtrate. From the resulting solution the volatiles
were removed, giving a pale brown solid. Recrystallization of the
crude product was attained by gently heating a solution of toluene
and 2 (20 mL) and keeping it at ambient temperature. 2 separates
as pale brown crystals. Yield: 2.17 g (72%). Mp: 231 °C dec. IR
) 1432, λ ) 0.710 73 Å, T ) 133(2) K, µ(Mo KR) ) 1.334 mm-1
.
(KBr pellet): ν˜ 3599 s (OH), 2039 s, 1956 s, 1942 s (CO) cm-1
.
Of the 31 533 measured reflections, 5672 were independent (R(int)
) 0.0791). The final refinements converged at R1 ) 0.0610 for I
> 2σ(I) and wR2 ) 0.0632 for all data. The final difference Fourier
synthesis gave a minimum/maximum residual electron density of
1H NMR (500.13 MHz, d8-THF, 25 °C, TMS): δ 7.19-7.29 (m,
6H; m, p Ar H), 5.69 (s, 1H; γ-CH), 4.24 (s, 1H; OH), 3.67 (sept,
3
3
2H, JH-H ) 6.8 Hz; CH(CH3)2), 3.07 (sept, 2H, JH-H ) 6.8 Hz;
3
CH(CH3)2), 1.93 (s, 6H; CH3), 1.34 (d, 6H, JH-H ) 6.8 Hz; CH-
+0.406/-0.413 e Å-3
.
3
(CH3)2), 1.31 (d, 6H, JH-H ) 6.8 Hz; CH(CH3)2), 1.24 (d, 6H,
3JH-H ) 6.8 Hz; CH(CH3)2), 1.16 ppm (d, 6H, JH-H ) 6.8 Hz;
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.
3
CH(CH3)2). 13C NMR (125.75 MHz, d8-THF, 25 °C, TMS): δ
214.8 (CO), 169.0 (CN), 147.1, 145.0, 140.0, 129.5, 125.8, 125.4
(i, o, m, p Ar), 101.6 (γ-CH), 29.9 (CH3), 28.8 (CH(CH3)2), 25.6
(CH(CH3)2), 25.0 (CH(CH3)2), 24.8 (CH(CH3)2), 24.8 (CH(CH3)2),
24.4 ppm (CH(CH3)2). EI-MS (70 eV; m/z (%)): 676 (5) [M+],
Supporting Information Available: X-ray data (CIF) for 2 and
3. This material is available free of charge via the Internet at
http://pubs.acs.org.
592 (20) [M+ - 3CO], 564 (70) [M+ - 4CO], 491 (100) [M+
-
4CO - Fe - OH]. Anal. Calcd for C33H42FeGeN2O5 (675.13): C,
58.71; H, 6.27; N, 4.15. Found: C, 58.91; H, 6.20; N, 4.12.
Preparation of LGe(OH)Mn(CO)2Cp (3). Compound 1 (0.50
g, 0.98 mmol) and CpMn(CO)3 (0.20 g, 0.98 mmol) were dissolved
in THF (30 mL), and the mixture was irradiated for 3 h with UV
light, during which time the initial yellow solution became orange.
OM0600893
(13) Sheldrick, G. M. SHELXS-97, Program for Structure Solution. Acta
Crystallogr., Sect. A 1990, 46, 467-473.
(14) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure
Refinement; University of Go¨ttingen, Go¨ttingen, Germany, 1997.