The chloromethylgermyl complexes (η5-C5H 5)M(CO)nGeR2CH2Cl [M = Fe (n = 2), Mo, W (n = 3)]: Rearrangements, transformations to 1-germa-3-metallacyclobutanes (η5-C5H4)M(CO)nCH 2GeR2, and their ring-opening polymerizations

Article abstract of DOI:10.1021/om800059r

The reactions between the transition metal-carbonylate salts [(η⁵-C₅H₅)M(CO)_n]^- Na⁺ (M = Fe (n = 2), Mo, W (n = 3)) and ClCH₂GeR ₂Cl result in the high-yield formation of (η⁵-C ₅H₅)M(CO)_nGeR₂CH₂Cl (M = Fe, R = Me (1), n-Bu (2); M = Mo, R = Me (3), R = n-Bu (4); M = W, R = Me (5), R = n-Bu (6)). Complexes 1, 2, 5, and 6 are transformed into the isomers (η⁵-C₅H₅)M(CO)_nCH ₂GeR₂Cl (1a, 2a, 5a, and 6a) thermally and/or photochemically. Treatment of either type of complex and the Mo complexes 3 and 4 with lithium diisopropylamide results in the formation of the metallacycles (η⁵-O₅H₄)M(CO)_nCH ₂OeR₂ (7-12). The metallacycles of Mo and W (9 and 11) are crystalline complexes, and single-crystal X-ray analysis reveals a degree of ring strain. However, these complexes cannot be ring-opened, in contrast to the corresponding Fe complexes (7 and 8), which readily form new polymeric materials [(η⁵-C₅H₄)Fe(CO)₂CH ₂GeR₂]_n.

Full text of DOI:10.1021/om800059r

3136
Organometallics 2008, 27, 3136–3141
The Chloromethylgermyl Complexes (η5-C5H5)M(CO)nGeR2CH2Cl
[M ) Fe (n ) 2), Mo, W (n ) 3)]: Rearrangements,
Transformations to 1-Germa-3-metallacyclobutanes
(η5-C5H4)M(CO)nCH2GeR2, and their Ring-Opening Polymerizations
Paula Apodaca, Mukesh Kumar, Francisco Cervantes-Lee,† Hemant K. Sharma, and
Keith H. Pannell*
Department of Chemistry, The UniVersity of Texas at El Paso, El Paso, Texas 79968-0513
ReceiVed January 22, 2008
The reactions between the transition metal-carbonylate salts [(η5-C5H5)M(CO)n]-Na+ (M ) Fe (n )
2), Mo, W (n ) 3)) and ClCH2GeR2Cl result in the high-yield formation of (η5-C5H5)M(CO)nGeR2CH2Cl
(M ) Fe, R ) Me (1), n-Bu (2); M ) Mo, R ) Me (3), R ) n-Bu (4); M ) W, R ) Me (5), R ) n-Bu
(6)). Complexes 1, 2, 5, and 6 are transformed into the isomers (η5-C5H5)M(CO)nCH2GeR2Cl (1a, 2a,
5a, and 6a) thermally and/or photochemically. Treatment of either type of complex and the Mo complexes
3 and 4 with lithium diisopropylamide results in the formation of the metallacycles (η5-
C5H4)M(CO)nCH2GeR2 (7-12). The metallacycles of Mo and W (9 and 11) are crystalline complexes,
and single-crystal X-ray analysis reveals a degree of ring strain. However, these complexes cannot be
ring-opened, in contrast to the corresponding Fe complexes (7 and 8), which readily form new polymeric
materials [(η5-C5H4)Fe(CO)2CH2GeR2]n.
tetrahedral complexes with little ring strain in the metalla-
cycle portion of the structure, and no specific metallacy-
clobutane chemistry has been reported.7 However, they are
useful catalysts for the polymerization of olefins.8 Although,
Introduction
Ring-opening of well-defined metallacycles can lead to
attractive materials with potential applications as catalysts,1
ion-exchange resins,2 polymeric support materials,3 precur-
sors for ceramic materials,4 conducting polymers,5,6 and
chemical sensors.6 There are limited reports on the synthesis
and reactivity of germametallacyclobutanes.7 ansa-Dimeth-
ylgermyldicyclopentadienyl ligands of Zr, Hf, and Ti yield
1-sila-3-metallacyclobutanes, Cp2MCH2SiMe2CH2, (M ) Ti,
Zr, Hf)1a are known for their ring expansion chemistry, such
chemistry is not reported for the related germa7a and stanna7b
derivatives. On the other hand, 1-germa- and stannaferro-
cenophanes have been studied and shown to readily ring open
to form interesting high molecular weight polymers.9
* Corresponding author. E-mail: kpannell@utep.edu.
† Deceased February 15, 2007.
(1) (a) Sharma, H. K.; Pannell. K. H. In Metal-Containing and Metallo-
Supramolecular Polymers and Materials; Schubert, U. S., Newkome, G. R.,
Manners, I., Eds.; Oxford University Press: Washington, DC, 2006. (b)
Zeldin, M.; Wynne, K. J.; Allcock, H. R. Inorganic and Organometallic
Polymers; ACS Symposium Series 360; American Chemical Society:
Washington, DC, 1988. (c) Pittman, C. U., Jr.; Carraher, C. E.; Zelden,
M.; Sheats, J. E., Jr.; Culbertson, B. M. In Metal-Containing Polymeric
Systems; Sheats, J. E., Carraher, C. E., Jr., Pittman, C. U., Jr., Eds.; Plenum
Press: New York, 1996. (d) Kinborough, R. P.; Swager, T. M. Prog. Inorg.
Chem. 1999, 48, 123. (e) Allcock, H. R. AdV. Mater. 1994, 6, 106. (f)
Rosenblum, M. AdV. Mater. 1994, 2, 159. (g) Abd-El-Aziz, A. S., Ed. Metal
and Metalloid Containing Macromolecules; Wiley-VCH: Weinheim, Ger-
many, 2003.
(2) Chemical Reactions on Polymers; Benham, J. L., Kinstle, J. F., Eds.;
ACS Symposium Series 364; American Chemical Society: Washington, DC,
1988.
(3) (a) Macomber, D. W.; Hart, W. P.; Rausch, M. D. In AdVances in
Organometallic Chemistry; Stone, F. G. A., West, R., Eds.; Academic Press:
New York, 1982; pp 1-55. (b) Tenhaeff, S. C.; Tyler, D. R. Organome-
tallics 1991, 10, 473.
(6) (a) Nguyen, M. T.; Diaz, A. F.; Dementiev, V. V.; Pannell, K. H.
Chem. Mater. 1993, 5, 1389. (b) Pannell, K. H.; Dementiev, V. V.; Li, H.;
Cervantes-Lee, F.; Nguyen, M. T.; Diaz, A. F. Organometallics 1994, 13,
3644. (c) Kapoor, R. N.; Crawford, G.; Mahmoud, J.; Dementiev, V. V.;
Nguyen, M. T.; Diaz, A. F.; Pannell, K. H. Organometallics 1995, 14, 4944.
(d) Castruita, M.; Cervantes-Lee, F.; Mahmoud, J. S.; Zhang, Y.; Pannell,
K. H. J. Organomet. Chem. 2001, 637-639, 664. (e) Espada, L.; Pannell,
K. H.; Papkov, V.; Leites, L.; Bukalov, S.; Suzdalev, I.; Tanaka, M.;
Hayashi, T. Organometallics 2002, 21, 3758. (f) Papkov, V. S.; Gerasimov,
M. V.; Dubovik, I. I.; Sharma, S.; Dementiev, V. V.; Pannell, K. H.
Macromolecules 2000, 33, 7107. (g) Espada, L.; Robillard, J.; Shadaram,
M.; Pannell, K. H. J. Inorg. Organomet. Polym. 2000, 10, 169.
(7) (a) Van De Heisteeg, B. J. J.; Schat, G.; Akkerman, O. S.;
Bickelhaupt, F. Tetrahedron Lett. 1984, 25, 5191. (b) Van De Heisteeg,
B. J. J.; Schat, G.; Akkerman, O. S.; Bickelhaupt, J. J. Organomet. Chem.
1986, 308, 1. (c) Tikkanen, W. R.; Egan, J. W.; Petersen, J. L. Organo-
metallics 1984, 3, 1646.
(4) (a) MacLachlan, M. J.; Ginzburg, M.; Coombs, N.; Coyle, T. W.;
Raju, N. P.; Greedan, J. E.; Ozin, G. A. ; Manners, I. Science 2000, 287,
1460. (b) Yajima, S.; Hayashi, J.; Omori, M. Chem. Lett. 1975, 931.
(5) (a) Nguyen, P.; Gomez-Elipe, P.; Manners, I. Chem. ReV. 1999, 99,
1515. (b) Manners, I. Angew. Chem., Int. Ed. Engl. 1996, 35, 1602. (c)
Manners, I. AdV. Organomet. Chem. 1995, 37, 131. (d) Resendes, R.; Nelson,
J. M.; Fischer, A.; Ja¨ckle, F.; Bartole, A.; Lough, A. J.; Manners, I. J. Am.
Chem. Soc. 2001, 123, 2116. (e) Kulbaba, K.; Cheng, A.; Bartole, A.;
Greenberg, S.; Resendes, R.; Coombs, N.; Safa-Sefat, A.; Greedan, J. E.;
Stoever, H. D. H.; Ozin, G. A.; Manners, I. J. Am. Chem. Soc. 2002, 124,
12522, and references therein.
(8) (a) Ko¨pf, H.; Kahl, W. J. Organomet. Chem. 1974, 64, C37. (b)
Chen, Y. X.; Rausch, M. D.; Chien, J. C. W. Organometallics 1994, 13,
748. (c) Patsidis, K.; Alt, H. G.; Milius, W.; Palackal, S. J. J. Organomet.
Chem. 1996, 509, 63. (d) Yamaguchi, Y.; Suzuki, N.; Fries, A.; Mise, T.;
Koshino, H.; Ikegami, Y.; Ohmori, H.; Matsumoto, A. J. Polym. Sci. Part
A: Polym. Chem. 1999, 37, 283. (e) Tian, G.; Wang, B.; Dai, X.; Xu, S.;
Zhou, X.; Sun, J. J. Organomet. Chem. 2001, 634, 145. (f) Xu, S.; Dai, X.;
Wang, B.; Zhou, X. J. Organomet. Chem. 2002, 645, 262. (g) Moreno,
C. A.; Antin˜olo, A.; Lopez-Solera, I.; Otero, A.; Prashar, S.; Rodr´ıguez,
A. M.; Villasen˜or, E. J. Organomet. Chem. 2002, 656, 129. (i) Alt, H. G.
Dalton Trans. 2005, 20, 3271.
10.1021/om800059r CCC: $40.75
2008 American Chemical Society
Publication on Web 06/07/2008

Complexes (η5-C5H5)M(CO)nGeR2CH2Cl [M ) Fe (n ) 2), Mo, W (n ) 3)]
We recently reported a series of 1-sila-3-ferracycles (η5-
Organometallics, Vol. 27, No. 13, 2008 3137
Scheme 1
C5H4)Fe(CO)2ER2SiR2′ (ER2 ) CH2, SiR2; R′ ) Me, n-Bu)
that under certain conditions ring-opened to organometallic
polymers.10 We now report the synthesis, characterization,
rearrangements, and ring-opening polymerization of 1-germa-
3-metallacyclobutanes, (η5-C5H4)M(CO)nCH2GeR2 [M ) Mo,
W (n ) 3); Fe (n ) 2) and R ) Me, Bu].
Results and Discussion
Using standard salt-elimination chemistry the synthesis of a
series of dialkyl(chloromethyl)germyl metal complexes,
MpGeR2CH2Cl, was accomplished in moderate yields as
outlined in eq 1, Mp ) (η5-C5H5)Fe(CO)2 [R ) Me (1), n-Bu
(2)]; (η5-C5H5)Mo(CO)3 [R ) Me (3), n-Bu (4)]; (η5-
C5H5)W(CO)3 [R ) Me (5), Bu (6)].
[Mp]-Na+ + ClGeR2CH2Cl f MpGeR2CH2Cl + NaCl
analysis, but they cannot be more stable by ∼14.8 kcal/mol than
the respective Fe-C and W-C bond energies (EFe-C ) 68.0
kcal/mol,15 EW-C ) 60.8 kcal/mol).16 However, it is of interest
that the Mo derivative, (η5-C5H5)Mo(CO)3GeMe2CH2Cl, did
not rearrange either thermally or photochemically, presumably
due to the higher Mo-Ge bond energy as compared to the
Mo-C bond, as indicated by available data (EMo-Ge ) 51.5
kcal/mol, EMo-C ) 33.2 kcal/mol,14,17 ∆E ) 18.3 kcal/mol).
Treatment of complexes 1-6, 1a, 2a, and 6a containing
M-Ge or M-C bonds with 1 equiv of lithium diisopropyl-
amide, LDA, resulted in the initial formation of the correspond-
ing 1-alkylgerma-3-metallacyclobutanes in high yield (∼80%),
Scheme 2, pathway A. In all cases the initial proof for the
formation of the metallacyclobutanes was the observation of
the ring methylene resonance in the 13C NMR spectra at between
ca. -50 and -65 ppm.
Isolation of the cyclobutanes was dependent upon the metal
involved. In the case of the Mo and W complexes, 9-12, these
metallacyclobutanes were isolated as stable crystalline materials.
The dimethylgerma iron complex 7 was short-lived and
transformed to a polymer 7a, Mw ) 2.5 × 103, Mn ) 2.2 ×
103, (Mw/Mn) ) 1.13 (Scheme 2, B).
The corresponding butylgermyl iron complex 8 was stable
enough for isolation and purification by column chromatogra-
phy; however, it also undergoes a ring-opening polymerization
if it is kept for a prolonged time (∼ a month) even at low
temperature (0 °C), resulting in the formation of polymer 8a,
Mw ) 5.4 × 103, Mn ) 2.5 × 103, PDI (Mw/Mn) ) 2.1. This
differs from our results with the silicon analogue di-n-butylsi-
(1)
The photolysis of benzene solutions of complexes
MpGeR2CH2Cl (1, 2, and 6) in sealed Pyrex NMR tubes for
14-24 h resulted in quantitative rearrangement to the isomeric
complexes MpCH2GeR2Cl [M ) Fe, R ) Me (1a), n-Bu (2a)
and M ) W, R ) n-Bu (6a)] containing a direct M-C bond.
Benzene solutions of the iron complexes 1 and 2 also rearranged
thermally to 1a and 2a, reminiscent of the thermal rearrangement
of (η5-C5H5)Fe(CO)2SiMe2CH2Cl to (η5-C5H5)Fe(CO)2CH2
SiMe2Cl.10,11 The iron isomers 1a and 2a were easily distin-
guished by the 13C resonances of the methylene group, -16.8
ppm (1a, Fe-CH2Ge), -20.6 ppm (2a, Fe-CH2Ge) versus those
of their parent complexes, 37.6 ppm (1, Fe-GeCH2), 35.2 ppm
(2, Fe-GeCH2). Infrared spectroscopy was also useful to
distinguish the two sets of isomers, and the carbonyl stretching
frequencies for the Fp-Ge complex 1 are ∼10 cm-1 lower than
the carbonyl stretching frequencies of Fp-C complex 1a.12 It is
possible that the mechanism of the photochemical rearrangement
may involve the initial decarbonylation to generate a 16e-
coordinatively unsaturated complex followed by ꢀ-elimination
of chlorine to the metal center to generate a transient germene
complex. The recoordination of CO drives the migration of
chlorine to the germanium, Scheme 1, to effect the rearrange-
ment process. Presumably the initial formation of the M-Ge
complexes is associated with the greater kinetic lability of the
Ge-Cl bond versus the C-Cl bond. However, the greater bond
energy of the Ge-Cl versus C-Cl (EGe-Cl ) 83.1 kcal/mol;13
EC-Cl ) 68.3 kcal/mol14) is in large measure the driving force
for the formation of the thermodynamically stable product. The
EFe-Ge and EW-Ge data are not available to complete this
laferracyclobutane, (η5-C5H4)Fe(CO)2CH2SiBu2, which was
found to be very stable.10a TGA analysis of the polymers 7a
and 8a showed an onset of weight loss between 200 and 300
°C, resulting in ∼45% residual mass at 650 °C.
(9) (a) Foucher, D. A.; Manners, I. Macromol. Rapid Commun. 1993,
14, 63. (b) Foucher, D. A.; Edwards, M.; Burrow, R. A.; Lough, A. J.;
Manners, I. Organometallics 1994, 13, 4959. (c) Reddy, N. P.; Yamashita,
H.; Tanaka, M. Chem. Commun. 1995, 22, 2263. (d) Zu¨rcher, S.; Gramlich,
V.; Togni, A. Inorg. Chim. Acta 1999, 291, 355. (e) Jakle, F.; Rulkens, R.;
Zech, G.; Foucher, D. A.; Lough, A. J.; Manners, I. Chem.-Eur. J. 1998,
4, 2117.
X-ray Crystal Structures of 9 and 11. The molecular
structures of 9 and 11 are shown in Figure 1. The two
metallacycles are isostructural and crystallize in the triclinic
j
space group P1, and the asymmetric unit contains two molecules
for each of the metallacycles with little variations in the bond
lengths and angles. They exhibit almost planar cyclobutane
rings, and the ligands are disposed in a distorted four-legged
(10) (a) Sharma, H. K.; Cervantes-Lee, F.; Pannell, K. H. J. Am. Chem.
Soc. 2004, 126, 1326. (b) Sharma, H. K.; Pannell, K. H. Chem. Commun.
2004, 2556.
(11) (a) Windus, C.; Sujishi, S.; Giering, W. P. J. Am. Chem. Soc. 1974,
96, 1951. (b) Windus, C.; Sujishi, S.; Giering, W. P. J. Organomet. Chem.
1975, 101, 279.
(15) Armentrout, P. B.; Halle, L. F.; Beauchamp, J. L. J. Am. Chem.
Soc. 1981, 103, 6501.
(12) Pannell, K. H.; Wu, C. C. J. Organomet. Chem. 1980, 186, 85.
(13) Martinho Simoes, J. A.; Beauchamp, J. L. Chem. ReV. 1990, 90,
629.
(16) Armentrout, P. B. J. Phys. Chem. A 2006, 110, 8327.
(17) Vincent, J. L.; Luo, S.; Scott, B. L.; Butcher, R.; Unkefer, C. J.;
Burns, C. J.; Kubas, G. J.; Lleods, A.; Maseras, F.; Toma`s, J. Organome-
tallics 2003, 22, 5307.
(14) Kumaran, S. S.; Su, M.-C.; Lim, K. P.; Michael, J. V.; Wagner,
A. F.; Harding, L. B.; Dixon, D. A. J. Phys. Chem. 1996, 100, 7541.

3138 Organometallics, Vol. 27, No. 13, 2008
Apodaca et al.
Scheme 2
piano stool fashion as observed for analogous tricarbonyl
cyclopentadienyl group 6 metal complexes.18 The angles
between adjacent atoms in the ring vary from 74.3° to 94.3 (4)°
in 9 and 74.1° to 96.3 (4)° in 11 and are also typical for these
types of structures (Table 2).18 The internal angles of the four-
membered ring differ significantly from the values of normal
tetrahedral angles, indicating that the cyclic portion of the
molecules composed of M-C-Ge-C possesses a significant
strain and causes the cyclobutane ring to be puckered with
folding angles of 15.5° (9, molecule 1), 9.8° (9, molecule 2)
and 9.9° (11, molecule 1), 16° (11, molecule 2). Despite the
ring strain, to date these metallacycles have not exhibited a
propensity for ring-opening polymerization.
Metallacycle Reactivity. The Mo metallacycle (9) was
treated with a range of reagents including a radical initiator
(AIBN), anionic and base species (n-BuLi, LDA, Et3N), and
transition metal complexes such as (PPh3)4Pd in attempts to
observe ring-opened polymerization. None of these experiments
were successful.
2
C5H4)Mo(CO)2{(PhO)3P}CH2GeMe2 [233.9 (d, CO, JP-C
)
33.8 Hz); -47.2 (d, CH2, JP-C ) 8.4 Hz)].19 In addition to
that, other molybdenum complexes, (η5-C5H5)Mo(CO)2(L)R (L
) P(OR3), PR3; R ) H, Hal, Me, PhCH2, etc.),20 revealed the
increase of trans-isomer percentage on increasing the steric bulk
around the metal atom; for example, L ) Ph3P, R ) Me, PhCH2
forms >99% trans-isomer. Similarly, W complexes (η5-
C5H5)W(CO)2(Ph3P)X (X ) alkyl)21 are reported to adopt a
trans-isomeric form on increaing the steric bulk around the metal
atom.
No fluxional behavior for these compounds in solution state
has been seen in the NMR spectroscopy, which is authenticated
by the presence of only one doublet in the methylene and
carbonyl region.
2
Experimental Procedures
All syntheses were performed using standard Schlenk techniques
under nitrogen atmospheres. The required glassware was oven-dried
at 100 °C for a period of 12 h, assembled hot and cooled under
vacuum, and purged with nitrogen. Reagent grade tetrahydrofuran
(THF) was dried and distilled from sodium-benzophenone. Benzene,
hexanes, and toluene were dried and distilled from Na wire. The
following reagents were purchased from Aldrich and used as
received: bromobenzene, bromochloromethane, diisopropylamine,
and n-BuLi (as a 1.6 M solution in hexanes). Dimethyldichlorog-
ermane and di-n-butyldichlorogermane were purchased from Gelest
and used as received. The dimers [(η5-C5H5)(CO)2Fe]2 and [(η5-
C5H5)(CO)3Mo]2 were purchased from Strem Chemical; [(η5-
C5H5)(CO)3W]2 was purchased from Acros Organics. Lithium
diisopropylamide (LDA) was freshly prepared from (1.6 M) n-BuLi
and diisopropyl amine. Solution NMR spectra were recorded on a
The thermal reaction of 9 and 11 with Ph3P in THF
resulted in the formation of the simple phosphine-substituted
products (η5-C5H4)Mo(CO)2(Ph3P)CH2GeMe2 (9a) and (η5-
C5H4)W(CO)2(Ph3P)CH2GeMe2 (11a) (eq 2).
(2)
Infrared and 13C NMR spectral values indicated that 9a [1920
(vs), 1843 cm-1 (s); -47.2 (d, CH2, 2JP-C ) 7.6 Hz); 228.6 (d,
(18) Schmitzer, S.; Weis, U.; Kab, H.; Buchner, W.; Malisch, W.; Polzer,
T.; Posset, U.; Kiefer, W. Inorg. Chem. 1993, 32, 303.
2
CO, JP-C ) 16.5 Hz)] and 11a [1918 (vs), 1847 cm-1 (s);
2
2
(19) Apodaca, P. New Transition Metal Complexes and their Ring
Opened Polymers. Ph.D Thesis, University of Texas at El Paso, 2006.
(20) Faller, J. W.; Anderson, A. S. J. Am. Chem. Soc. 1970, 92, 5852.
(21) George, T. A.; Sterner, C. D. Inorg. Chem. 1976, 15, 165.
-57.6 (d, CH2, JP-C ) 7.3 Hz); 228.6 (d, CO, JP-C ) 16.0
Hz)] adopt the trans-isomeric form. The 13C NMR spectral data
of compound 9a are similar to those of trans-(η5-

Complexes (η5-C5H5)M(CO)nGeR2CH2Cl [M ) Fe (n ) 2), Mo, W (n ) 3)]
Organometallics, Vol. 27, No. 13, 2008 3139
Table 1. Summary of X-ray Crystallographic Data of 9 and 11
9
11
empirical formula
C11H12GeMoO3
360.74
296(2)
C11H12GeWO3
448.65
296(2)
0.17073
triclinic
j
P1
formula weight
temperature (K)
λ(Mo KR) (Å)
cryst syst
space group
unit cell dimens
a (Å)
0.17073
triclinic
j
P1
6.8366(7)
13.3860(15)
14.6784(16)
82.52(2)
79.88(2)
81.76(2)
1301.2(2)
4
1.841
6.822(2)
13.361(4)
14.685(4)
82.50
79.76
81.87
1296.4(6)
4
2.299
0.20 × 0.20 × 0.06
b (Å)
c (Å)
R (deg)
ꢀ (deg)
γ (deg)
volume (A3)
Z
calcd density (Mg/m3)
cryst size (mm)
refinement method
final R (Rw)
0.40 × 0.20 × 0.06
full-matrix least-squares on F2
R1 ) 0.057
wR2 ) 0.1200
R1 ) 0.044
wR2 ) 0.108
as a dark red viscous material. Anal. Calcd for C10H13FeO2GeCl:
C, 36.49, H, 3.98. Found: C, 37.29, H, 4.04. 1H NMR (C6D6): 0.59
(s, 6H, Me), 3.06 (s, 2H, CH2), 4.01 (s, 5H, C5H5). 13C NMR
(C6D6): 3.93 (Me), 37.6 (CH2), 83.0 (C5H5), 215.9 (CO). IR (ν CO,
cm-1, hexanes): 2001, 1952.
(η5-C5H5)Fe(CO)2GeBu2CH2Cl (2). As above FpGeBu2CH2Cl
(2) was obtained as a red viscous material from the reaction of
[(η5-C5H5)Fe(CO)2]-Na+ (prepared from 2.0 g (5.6 mmol) of [η5-
C5H5)Fe(CO)2]2) and 2.9 g (11.0 mmol) of ClCH2GeBu2Cl;17 yield
3.8 g, 9.2 mmol, 84%. Anal. Calcd for C16H25FeO2GeCl (mol wt
1
413.28): C, 46.50; H, 6.10. Found: C, 47.05; H, 6.25. H NMR
(C6D6): 0.96 (m, 6H, Bu), 1.21-1.50 (m, 12H, Bu), 3.20 (s, 2H,
CH2), 4.14 (s, 5H, C5H5). 13C NMR (C6D6): 13.9, 20.4, 26.8, 28.7
(Bu), 35.2 (CH2), 82.5 (C5H5), 215.7 (CO). IR (ν CO, cm-1, THF):
1999, 1951.
Figure 1. ORTEP diagram of the molecular structures of (η5-
C5H5)Mo(CO)3CH2GeMe2 (9) and (η5-C5H5)W(CO)3CH2GeMe2
(11). Thermal ellipsoids are drawn at the 50% probability level
(only one molecule of each compound is shown).
(η5-C5H5)Mo(CO)3GeMe2CH2Cl (3). In a manner similar to
that described above (η5-C5H5)Mo(CO)3GeMe2CH2Cl (3) was
obtained as a pale pink solid from the reaction between [(η5-
C5H5)Mo(CO)3]-Na+ (prepared from 0.88 g (1.80 mmol) of [(η5-
C5H5)Mo(CO)3]2) and 0.70 g (3.60 mmol) of ClCH2GeMe2Cl;
yield (1.2 g, 3.0 mmol, 90%), mp 78 °C. Anal. Calcd for
C11H13MoO3GeCl: C, 33.26; H, 3.30. Found: C, 33.22; H, 3.42.
1H NMR (C6D6): 0.69 (s, 6H, Me), 3.17 (s, 2H, CH2), 4.47 (s, 5H,
C5H5). 13C NMR (C6D6): 3.18 (Me), 36.8 (CH2), 89.9 (C5H5), 225.8,
231.0 (CO). IR (ν CO, cm-1, THF): 1999, 1926, 1901.
Bruker 300 MHz spectrometer using CDCl3 or C6D6 as solvent
and reported as ppm; infrared spectra were recorded on an ATI
Mattson Infinity Series FTIR; elemental analyses were performed
by Galbraith Laboratories. Gel permeation chromatography (GPC)
analysis of the molecular weight distribution of the polymers was
performed on a high-performance liquid chromatography (HPLC)
instrument comprised of a Spectra-Physics Spectra System P1500
gradient pump, UV2000 detector, and Winner for Windows
software. A Waters 7.8 × 300 mm Styragel column packed with 5
µm particles of mixed pore size and highly cross-linked styrene-
divinylbenzene copolymer particles maintained at 24 °C was used
for the analysis. The eluting solvent was HPLC grade THF at a
flow rate of 1.0 mL/min. The retention times were calibrated against
known polystyrene standards at molecular weights of 4000, 18 700,
44 000, 97 000, and 212 400.
(η5-C5H5)Mo(CO)3GeBu2CH2Cl (4). The reaction between [(η5-
C5H5)Mo(CO)3]-Na+ (prepared from 2.0 g (4.10 mmol) of [(η5-
C5H5)Mo(CO)3]2) and 2.90 g (10.0 mmol) of ClCH2GeBu2Cl
afforded (4.0 g, 8.30 mmol, 83%) (η5-C5H5)Mo(CO)3GeBu2CH2Cl
(5) as a pale pink oil. Anal. Calcd for C17H25MoO3GeCl: C, 42.42;
H, 5.23. Found: C, 42.26; H, 5.19. 1H NMR (C6D6): 0.93 (m, 6H,
Bu), 1.45 (m, 12H, Bu), 3.36 (s, 2H, CH2), 4.66 (s, 5H, C5H5). 13
C
NMR (C6D6): 13.4, 20.4, 26.3, 28.5 (Bu), 35.0 (CH2), 89.3 (C5H5),
225.7, 230.9 (CO). IR (ν CO, cm-1, hexanes): 2005, 1936, 1913.
(η5-C5H5)W(CO)3GeMe2CH2Cl (5). As above, the reaction
between [(η5-C5H5)W(CO)3]-Na+ (prepared from 1.0 g (1.50
mmol) of [(η5-C5H5)W(CO)3]2) and 0.56 g (3.0 mmol) of
ClCH2GeMe2Cl afforded (1.2 g, 2.47 mmol, 82.7%) of (η5-
C5H5)W(CO)3GeMe2CH2Cl (3) as a yellow solid, mp 86 °C. Anal.
Calcd for C11H13WO3GeCl: C, 27.23; H, 2.70. Found: C, 27.01;
Synthesis of (η5-C5H5)Fe(CO)2GeMe2CH2Cl (1). To 60 mL
of a THF solution of [(η5-C5H5)Fe(CO)2]-Na+ (prepared from
1.40 g (4.0 mmol) of [(η5-C5H5)Fe(CO)2]2) was added, via syringe,
1.5 g (8.0 mmol) of ClCH2GeMe2Cl22 in 10 mL of THF at -78
°C. The solution was initially stirred at low temperature, warmed
to room temperature, and further stirred overnight. The solvent was
removed under vacuum, the residue was extracted with 40 mL of
hexane and filtered through Celite, and the solvent was removed
under vacuum. The residue was redissolved in 30 mL of hexane
and again filtered through Celite. Removal of the solvent afforded
(2.0 g, 6.0 mmol, 77% yield) (η5-C5H5)Fe(CO)2GeMe2CH2Cl (1)
1
H, 2.65. H NMR (C6D6): 0.72 (s, 6 H, Me), 3.20 (s, 2H, CH2),
4.47 (s, 5H, C5H5). 13C NMR (C6D6): 2.36 (Me), 36.1 (CH2), 82.6
(C5H5), 215.6, 219.3 (CO). IR (ν CO, cm-1, hexanes): 2005, 1930,
1909.
(η5-C5H5)W(CO)3GeBu2CH2Cl (6). The reaction between [(η5-
C5H5)W(CO)3]-Na+ (prepared from 1.0 g (1.50 mmol) of [(η5-
C5H5)W(CO)3]2) and 0.81 g (3.0 mmol) of ClCH2GeBu2Cl afforded
(22) Kobayashi, T.; Pannell, K. H. Organometallics 1990, 9, 2201.

3140 Organometallics, Vol. 27, No. 13, 2008
Apodaca et al.
Table 2. Selected Bond Lengths (Å) and Angles (deg) of 9 and 11
Complex 9
Mo-C(6)
2.360(9)
2.336(8)
74.3(3)
93.3(4)
C(6)-Ge(1)
Ge(1)-C(7)
1.928(10)
1.933(11)
Ge(1)-C(1)
1.970(9)
1.933(11)
94.9(3)
C(1)-Mo(1)
Ge(1)-C(8)
C(1)-Mo(1)-C(6)
C(1)-Ge(1)-C(6)
Mo(1)-C(1)-Ge(1)
Ge(1)-C(6)-Mo(1)
95.3(4)
Complex 11
W(1)-C(6)
2.337(11)
2.334(10)
74.4(3)
C(6)-Ge(1)
Ge(1)-C(10)
1.940(11)
1.960(12)
Ge(1)-C(1)
1.962(12)
1.941(14)
95.8(4)
C(1)-W(1)
Ge(1)-C(11)
C(1)-W(1)-C(6)
C(1)-Ge(1)-C(6)
W(1)-C(1)-Ge(1)
Ge(1)-C(6)-W(1)
92.8(4)
96.3(4)
(1.44 g, 2.50 mmol, 85.0%) of (η5-C5H5)W(CO)3GeBu2CH2Cl (6)
as a yellow oil. Anal. Calcd for C17H25WO3GeCl: C, 35.87; H,
4.43. Found: C, 36.21; H, 4.32. 1H NMR (C6D6): 0.94 (m, 6H,
opening behavior, which eventually led to the formation of 7a in
quantitative yield. The solution of 7 in THF transformed into 7a at
low temperature (0 °C) after ∼24-48 h. The purification of the
polymer 7a was done by repeated precipitation of a THF solution
into hexanes. The spectroscopic data indicated the formation of
polymer 7a in 70% yield. 1H NMR (CDCl3): 0.11 (2H, CH2), 0.36
(6H, GeMe2), 4.3-4.8 (4H, C5H4). 13C NMR (CDCl3): -22.1
(CH2), 84.7 (ipso, C5H4), 87.8, 91.2 (C5H4), 217.7 (CO). IR (ν CO,
cm-1, THF): 1999, 1943. GPC in THF: Mw ) 2563, Mn ) 2263,
PDI (Mw/Mn) ) 1.13.
Bu), 1.44 (m, 12H, Bu), 3.40 (s, 2H, CH2), 4.66 (s, 5H, C5H5). 13
C
NMR (C6D6): 13.9, 19.9, 26.8, 29.1 (Bu), 34.8 (CH2), 88.5 (C5H5),
216.1, 219.7 (CO). IR (ν CO, cm-1, hexanes): 2003, 1928, 1907.
Synthesis of (η5-C5H5)Fe(CO)2CH2GeMe2Cl (1a). A solution
of 100 mg of (η5-C5H5)Fe(CO)2GeMe2CH2Cl in 1 mL of C6D6 was
degassed and sealed in an NMR tube. The NMR tube was placed
in an oil bath at a temperature of 90-100 °C, and the progress of
the reaction was followed by 13C NMR. After 16 h the reaction
was completed and the spectroscopic data indicated the quantitative
formation of the rearranged product, 91% yield (0.9 g, 2.7 mmol).
The photolysis of FpGeMe2CH2Cl in a sealed NMR tube for 48 h
also afforded the rearranged compound in an 80% yield along with
some decomposition. Anal. Calcd for C10H13FeO2GeCl: C, 36.49;
Synthesis of (η5-C5H4)Fe(CO)2CH2GeBu2 (8). Complex 8 was
synthesized as described above by treatment of either (η5-
C5H5)Fe(CO)2GeBu2CH2Cl or (η5-C5H5)Fe(CO)2CH2GeBu2Cl with
freshly prepared LDA. After removal of the solvent the red-brown
residue was extracted with hexanes and filtered on Celite. Evapora-
tion of the solvent yielded the pure stable germametallacycle (8)
as a red oil (70% yield). Anal. Calcd for C16H24FeO2Ge: C, 42.44;
1
H, 3.98. Found: C, 36.81; H, 3.84. H NMR (C6D6): 0.65 (s, 6H,
Me), 0.23 (s, 2H, CH2), 4.04 (s, 5H, C5H5). 13CNMR (C6D6): -16.8
1
H, 6.63. Found: C, 42.10; H, 6.55. H NMR (CDCl3): -1.21 (s,
(CH2), 6.6 (Me), 84.9 (C5H5), 216.7 (CO). IR (ν CO, cm-1
,
2H, CH2), 0.97-1.4 (m, 18H, Bu), 4.56, 4.64 (m, 4H, C5H4). 13C
NMR (C6D6): -54.4 (CH2), 13.9, 15.1, 26.5, 27.1 (Bu), 75.4, 86.4,
92.6 (C5H4), 218.5 (CO). IR (ν CO, cm-1, hexanes): 1999, 1947.
The germametallacycle was stored at low temperature (0 °C) for
30 days, and after this time the spectroscopic data indicated the
transformation of the metallacycle into the corresponding polymer
hexanes): 2017, 1965.
(η5-C5H5)Fe(CO)2CH2GeBu2Cl (2a). Compound 2a was ob-
1
tained in the same manner as 1a as a red oil in a 95% yield. H
NMR (C6D6): 0.26 (s, 2H, CH2), 0.92 (t, 6H, Bu), 1.16-1.60 (m,
12H, Bu), 4.19 (s, 5H, C5H5). 13C NMR (C6D6): -20.6 (CH2), 13.9,
21.7, 26.3, 26.9 (Bu), 85.2 (C5H5), 215.0 (CO). IR (ν CO, cm-1
,
1
(8a). H NMR (CDCl3): 0.11 (s, 2H, CH2), 0.95-1.40 (m, 18H,
THF): 2015, 1963. Elemental analysis could not be performed due
to continuous decomposition of the compound, which was used
immediately upon formation.
Bu), 4.67-4.81 (m, 4H, C5H4). 13C NMR (CDCl3): -26.1 (CH2),
13.7, 16.3, 26.6, 27.5 (Bu), 83.0 (ipso), 88.7, 91.2 (C5H4), 217.8
(CO). IR (ν CO, cm-1, THF): 1997, 1943. GPC in THF: Mw
5452, Mn ) 2526, PDI (Mw/Mn) ) 2.1.
)
Synthesis of (η5-C5H5)W(CO)3CH2GeBu2Cl (6a). A solution
of 100 mg of (η5-C5H5)W(CO)3GeBu2CH2Cl (6) in 1 mL of C6D6
was degassed and sealed in an NMR tube. The photochemical (350
nm) treatment of this solution resulted in the quantitative formation
of the rearranged product (6a). 1H NMR (C6D6): 0.57 (s, 2H, CH2),
0.95 (m, 6H, Bu), 1.44 (m, 12H, Bu), 4.57(s, 5H, C5H5). 13C NMR
(C6D6): -34.8 (CH2), 13.9, 22.5, 26.3, 26.9 (Bu), 88.5 (C5H5),
218.1, 229.4 (CO). IR (ν CO, cm-1, hexanes): 2021, 1937, 1926.
As with 2a, elemental analysis was unsuccessful, and the material
was used immediately upon formation.
Synthesis of (η5-C5H4)Mo(CO)3CH2GeR2 [R ) Me (9),
n-Bu (10)] and (η5-C5H4)W(CO)3CH2GeR2 [R ) Me (11),
n-Bu (12)]. The above compounds were synthesized in the same
manner, and the preparation of (η5-C5H4)Mo(CO)3CH2GeMe2 (9)
is described as a representative example. In a 50 mL round-
bottomed Schlenk flask was placed 1.0 g (2.52 mmol) of (η5-
C5H5)Mo(CO)3GeMe2CH2Cl in 20 mL of THF. To this solution at
-25 °C was added 1.5 mL (2.6 mmol) of freshly prepared LDA in
the same solvent via cannula. The color of the reaction solution
immediately changed from a light yellow to dark red. The solution
was stirred for 30 min at low temperature and overnight at room
temperature. After removal of the solvent, the brown residue was
extracted with hexanes and filtered on Celite. Evaporation of the
hexanes yielded a pink solid material along with some decomposed
material. After recrystallization from hexanes, 0.72 g (80%) of light
pink crystals were obtained. Spectroscopic data indicated the
Synthesis of (η5-C5H4)Fe(CO)2CH2GeMe2 (7). In a 50 mL
round-bottomed Schlenk flask was placed 0.6 g (1.8 mmol) of either
(η5-C5H5)Fe(CO)2GeMe2CH2Cl (1) or (η5-C5H5)Fe(CO)2CH2
GeMe2Cl (1a) in 10 mL of THF. To this solution at -25 °C was
added 1.5 mL (1.9 mmol) of freshly prepared LDA in the same
solvent via cannula. The color of the reaction solution immediately
changed from red to dark brown. The solution was stirred for 30
min at low temperature and for 2 h at room temperature, and the
formation of 7 was monitored by 13C NMR spectroscopy. After
that, the solvent was removed from the reaction mixture under
vacuum and the product was extracted with hexanes. The NMR
spectral data indicated the formation of the metallacycle 7. 1H NMR
(CDCl3): -1.53 (2H, s, CH2), 0.41 (3H, s, Me), 4.86 (t, J ) 1.5
Hz, 2H, C5H4), 5.13 (t, J ) 1.5 Hz, 2H, C5H4). 13C NMR (CDCl3):
-52.6 (CH2), -1.14, (Me), 82.7 (ipso), 85.6, 92.5 (C5H4), 217.9
(CO). IR (ν CO, cm-1, hexanes): 1957, 2009. Purification and
elemental analysis of 7 could not be done due to continuous ring-
formation of (η5-C5H4)Mo(CO)3CH2GeMe2 with no evidence of a
ring-opening polymerization. This metallacyle was stored under
nitrogen for several days, and no decomposition was observed. Mp:
66 °C. Anal. Calcd for C11H12MoO3Ge: C, 36.62; H, 3.35. Found:
1
C, 36.45; H, 3.50. H NMR (C6D6): -1.21 (s, 2H, CH2), 0.16 (s,
6H, Me), 4.71-5.00 (m, 4H, C5H4). 13C NMR (C6D6): -51.9
(CH2), -1.20 (Me), 80.5, 94.3, 95.9 (C5H4), 228.2, 239.5 (CO).
IR (ν CO, cm-1, hexanes): 2018, 1945, 1934.

Complexes (η5-C5H5)M(CO)nGeR2CH2Cl [M ) Fe (n ) 2), Mo, W (n ) 3)]
Organometallics, Vol. 27, No. 13, 2008 3141
recrystallized from a benzene/hexanes mixture to yield 9a or 11a
as an orange solid compound in 70% yield.
(η5-C5H4)Mo(CO)3CH2GeBu2 (10): yellow oil, 0.7g
(87%). Anal. Calcd for C17H24MoO3Ge: C, 45.89; H, 5.44. Found:
C, 45.78; H, 5.40. 1H NMR (C6D6): δ -1.19 (s, 2H, CH2),
0.84-0.91 (m, 12H, Bu), 1.31-1.36 (m, 6H, Bu), 4.77 (t, J ) 1.8
Hz, 2H, C5H4), 5.11 (t, J ) 1.8 Hz, 2H, C5H4). 13C NMR (C6D6):
-54.2 (CH2), 13.9, 15.1, 26.4, 26.8 (Bu), 79.5, 94.5, 96.5 (C5H4),
228.3, 239.5 (CO). IR (ν CO, cm-1, hexanes): 2017, 1943, 1932.
(η5-C5H4)Mo(CO)2(Ph3P)CH2GeMe2 (9a): orange solid, mp
131-132 °C (72%). Anal. Calcd for C28H27MoO2GeP: C, 56.45;
H, 4.70. Found: C, 56.52; H, 4.57. 1H NMR (C6D6): -0.30 (s, 2H,
CH2), 0.42 (s, 6H, Me), 4.40, 5.55 (m, 4H, C5H4), 7.10-7.90 (15H,
Ph). 13C NMR (C6D6): -47.2 (d, CH2, 2JP-C ) 7.6 Hz), 0.81 (Me),
89.6, 93.4, 94.9 (C5H4), 128.1, 130.9, 131.9, 132.8 (Ph), 228.6 (d,
(η5-C5H4)W(CO)3CH2GeMe2 (11): yellow solid, mp 98 °C
2
CO, JP-C ) 16.5 Hz). 31P NMR (C6D6): 42.7. IR (ν CO, cm-1
,
(82%). Anal. Calcd for C11H12WO3Ge: C, 29.45; H, 2.70. Found:
THF): 1920(vs), 1843(s).
1
C, 29.32, 2.63. H NMR (C6D6): 0.99 (s, 2H, CH2), 0.12 (s, 6H,
Me), 4.63, 5.07 (m, 4H, C5H4). 13C NMR (C6D6): -64.2 (CH2),
-1.20 (Me), 83.9, 92.1, 94.3 (C5H4), 217.6, 222.2 (CO). IR (ν CO,
cm-1, hexanes): 2015, 1936, 1926.
(η5-C5H4)W(CO)2(Ph3P)CH2GeMe2 (11a): orange solid, mp
145-148 °C (70%). Anal. Calcd for C28H27WO2GeP: C, 49.20;
H, 4.10. Found: C, 49.24; H, 3.98. 1H NMR (C6D6): -0.26 (s, 2H,
CH2), 0.49 (s, 6H, Me), 4.43, 5.58 (m, 4H, C5H4) 7.12- 7.87 (15H,
(η5-C5H4)W(CO)3CH2GeBu2 (12): yellow oil (77%). Anal.
Calcd for C17H24WO3Ge: C, 38.32; H, 4.54. Found: C, 38.29; H,
4.30. 1H NMR (CDCl3): -0.93 (s, 2H, CH2), 0.74-0.93 (m, 12H,
Bu), 1.25-1.39 (m, 6H, Bu), 4.67 (t, J) 1.5 Hz, 2H, C5H4), 5.17
(t, J ) 1.8 Hz, 2H, C5H4). 13C NMR (C6D6): -66.7 (CH2), 12.5,
15.1, 26.3, 26.6 (Bu), 82.9, 92.3, 94.9 (C5H4), 217.7, 229.3 (CO).
IR (ν CO, cm-1, hexanes): 2014, 1935, 1924.
2
Ph). 13C NMR (C6D6): -57.6 (d, CH2, JP-C ) 7.3 Hz), -1.10
(Me), 81.6, 92.2, 94.2 (C5H4), 128.7, 132.3, 133.9, 138.2 (Ph), 228.6
(d, CO, 2JP-C ) 16.0 Hz). 31P NMR (C6D6): 42.7 (1JW-P ) 262.0
Hz). IR (ν CO, cm-1, THF): 1918 (vs), 1847 (s).
Acknowledgment. This research has been supported by
the Robert Welch Foundation, Houston, TX (Grant #AH 546)
and an NIH SCORE grant.
Synthesis of (η5-C5H4)Mo(CO)2(Ph3P)CH2GeMe2 (9a) and
(η5-C5H4)W(CO)2(Ph3P)CH2GeMe2 (11a). To 0.5 mL of a THF
solution of 9 or 11 (1.0 mmol) in a NMR tube was added (1.10
mmol) PPh3, and the contents were degassed twice by freeze-thaw
cycles. The solution was then heated at 100 °C for ∼48 h. After
completion of the reaction the solvent was removed under vacuum.
The solid material obtained was extracted with hexanes and
Supporting Information Available: Crystallographic data in
CIF format (CCDC no. 670931 (for 9) and 670932 (for 11)). This
material is available free of charge via the Internet at http://pubs.
acs.org.
OM800059R