Synthesis and characterization of novel M-Hg-M (M = Cr, Mo, W) heterotrimetallic complexes bridged by a functionally substituted bis(cyclopentadienyl) ligand. Crystal and molecular structure of [Mo(CO)3(η

Article abstract of DOI:10.1021/om9508795

The bridged heterotrimetallic complexes with a general formula of [M(CO)₃(η⁵-C₅H₄ZC ₅H₄-η⁵)(CO)₃-M]Hg (M = Cr, Mo, W, Z = C(O)CH₂CH₂C(O); M = Mo, Z = CH₂CH₂OCH₂CH₂) can be readily prepared through reaction of PhHgCl with appropriate dianions ^-M(CO)₃-(η⁵-C₅H ₄ZC₅H₄-η⁵)(CO)₃M ^- in THF or diglyme. Their structures assigned by combustion analysis and spectroscopy are further confirmed by X-ray crystallography for one representative complex [Mo(CO)₃(η⁵-C₅H₄CH ₂-CH₂OCH₂CH₂C₅H ₄-η⁵(CO)₃Mo]Hg.

Full text of DOI:10.1021/om9508795

1954
Organometallics 1996, 15, 1954-1956
Syn th esis a n d Ch a r a cter iza tion of Novel M-Hg-M (M )
Cr , Mo, W) Heter otr im eta llic Com p lexes Br id ged by a
F u n ction a lly Su bstitu ted Bis(cyclop en ta d ien yl) Liga n d .
Cr ysta l a n d Molecu la r Str u ctu r e of
[Mo(CO)3(η5-C5H4CH2CH2OCH2CH2C5H4-η5)(CO)3-
Mo]Hg
Li-Cheng Song,* Yu-Bin Dong, and Qing-Mei Hu
Department of Chemistry, Nankai University, Tianjin 300071, China
J ie Sun
Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry,
Shanghai, China
Received November 7, 1995X
Summary: The bridged heterotrimetallic complexes with
a general formula of [M(CO)3(η5-C5H4ZC5H4-η5)(CO)3-
M]Hg (M ) Cr, Mo, W, Z ) C(O)CH2CH2C(O); M ) Mo,
Z ) CH2CH2OCH2CH2) can be readily prepared through
reaction of PhHgCl with appropriate dianions -M(CO)3-
(η5-C5H4ZC5H4-η5)(CO)3M- in THF or diglyme. Their
structures assigned by combustion analysis and spec-
troscopy are further confirmed by X-ray crystallography
for one representative complex [Mo(CO)3(η5-C5H4CH2-
CH2OCH2CH2C5H4-η5(CO)3Mo]Hg.
diffraction analysis for one representative compound are
also described.
Resu lts a n d Discu ssion
The functionally substituted bis(cyclopentadienyl)-
bridged group 6 metal dianion salts 1, derived from
M(CO)6 (M ) Cr, Mo, W) and [1,1′-(1,4-dioxabutane-1,4-
diyl)dicyclopentadienyl]disodium,14 or from Mo(CO)6
and [1,1′-(3-oxapentamethylene)dicyclopentadienyl]di-
sodium,15 have been shown to react in THF or diglyme
with PhHgCl to give four novel products 2a -d (eq 1)
as slightly air-sensative yellow solids in 35-65% yields.
In tr od u ction
Nonbridged M-Hg-M (M ) Cr, Mo, W) trimetallic
complexes containing cyclopentadienyl1-8 or substituted
cyclopentadienyl9-12 ligands are well documented in the
literature. There is, however, no corresponding bridged
M-Hg-M trimetallic complex reported yet in the
literature, up to now. In view of our interest in both
the novel formation method for M-Hg-M linkage and
the use of functionally substituted bis(cyclopentadienyl)
ligands in the synthesis of heteromultinuclear com-
plexes,13 we initiated this study. In this paper we report
the synthetic results of a series of M-Hg-M trimetallic
compounds bridged with functionally substituted bis-
(cyclopentadienyl) ligands, 1,4-bis(cyclopentadienyl)-1,4-
butadione and 1,5-bis(cyclopentadienyl)-3-oxapentane.
Structural characterization of the products and an X-ray
The bridged products 2a -d are much less soluble
in organic solvents than corresponding nonbridged
M-Hg-M compounds.1-12 For example, they all do not
dissolve in petroleum ether. While 2d is soluble in
CHCl3, CH2Cl2, and ether, 2a -c are not, but they are
soluble in more polar organic solvents such as THF and
DMSO. For 2a -c, the solubility decreases in the order
of 2b > 2c > 2a . The characterizing data for 2a -d are
in good agreement with the structures shown in eq 1.
For example, the IR spectra of 2a -c showed three bands
for terminal carbonyls in the range 1876-2033 cm-1 and
one band at about 1670 cm-1 for the ketone carbonyls,
while the IR spectrum of 2d exhibited three bands for
terminal carbonyls at 1950-1861 cm-1 and one C-O
X Abstract published in Advance ACS Abstracts, March 1, 1996.
(1) Fischer, E. O.; Hafner, W.; Stahl, H. O. Z. Anorg. Allg. Chem.
1955, 282, 47.
(2) Mays, M. J .; Robb, J . D. J . Chem. Soc. A 1968, 329.
(3) Salem, G.; Skelton, B. W.; White, A. H.; Wild, S. B. J . Chem.
Soc., Dalton Trans. 1983, 2117.
(4) Petersen, R. B.; Ragosta, J . M.; Whitwell, G. E., II, Burlitch, J .
M. Inorg. Chem. 1983, 22, 3407.
(5) Hackett, P.; O’Neill, P. S.; Manning, A. R. J . Chem. Soc., Dalton
Trans. 1974, 1625.
(6) Mays, M. J .; Robb, J . D. J . Chem. Soc. A 1969, 561.
(7) Mickiewicz, M. M.; Raston, C. L.; White, A. H.; Wild, S. B. Aust.
J . Chem. 1977, 30, 1685.
(8) Song, L.-C.; Hu, Q.-M.; Yang, H.; Shen, J .-Y. Chem. J . Chin.
Univ. 1991, 12, 198.
(9) Song, L.-C.; Yang, H.; Dong, Q.; Hu, Q.-M. J . Organomet. Chem.
1991, 414, 137.
(10) Song, L.-C.; Dong, Q.; Hu, Q.-M. Acta Chim. Sinica 1992, 50,
193.
stretching band at about 1134 cm-1
.
The 1H NMR
spectra of 2a -d all showed the presence of their
corresponding functionally substituted cyclopentadienyl
ligands; the EI mass spectrum of 2d showed its molec-
ular ion peak at m/z 766, while those of 2a -c exhibited
only their respective fragment ion peaks.
(11) Song, L.-C.; Tao, Z.-F.; Hu, Q.-M.; Wang, R.-J .; Wang, H.-G.
Polyhedron 1994, 13, 2179.
(12) Song, L.-C.; Hu, Q.-M.; Wang, R.-J .; Wang, H.-G. Acta Crys-
tallogr. 1994, C50, 1592.
(13) Song, L.-C.; Shen, J .-Y.; Hu, Q.-M.; Huang, X.-Y. Organome-
tallics 1995, 14, 98.
(14) Bitterwolf, T. E. J . Organomet. Chem. 1990, 386, 9.
(15) Qian, C.-T.; Xie, Z.-W.; Huang, Y.-Z. J . Organomet. Chem. 1987,
323, 285.
0276-7333/96/2315-1954$12.00/0 © 1996 American Chemical Society

Notes
Organometallics, Vol. 15, No. 7, 1996 1955
Hg.9 Two differences between 2d and its nonbridged
analogue [η5-EtO2CC5H4(CO)3Mo]2Hg10 should be indi-
cated. First, the bond angle of Mo-Hg-Mo in 2d is
171.43(4)° as mentioned above, while that of the ana-
logue is exactly the linear value of 180.03°; second, with
respect to the Mo-Hg-Mo structural unit the two
cyclopentadienyl rings (or six carbonyls) in 2d are cis
to each other, while those in the analogue are trans
(namely the analogue is centrosymmetric). Obviously,
these are due to the presence of the bridge (CH2)2O-
(CH2)2 linked to two cyclopentadienyl rings in 2d . It is
worth pointing out that the distance between O(1) and
Hg is only 2.87 Å, which is less than sum of their van
der Waals radii of 2.9-3.13 Å. This implies that an
intramolecular interaction between oxygen and mercury
atoms is present. Such kinds of weak interactions
between Hg and heteroatoms were already described in
the literature.16,17 These could be construed as arising
from the acceptor nature of the mercury center and the
donor nature of the oxygen atom.
F igu r e 1. ORTEP drawing of 2d with the atom-number-
ing scheme.
Ta ble 1. Selected Bon d Len gth s a n d An gles of 2d
It is interesting to note that the bridged trimetallic
complexes 2 could be regarded as macrocyclic ring
compounds involved with σ- and η5-π-types of bonds. At
present, it is not clear about the mechanism for this
ring-closure reaction by the action of PhHgCl on dianion
salts 1. According to a related mechanistic study,10
however, the ring-closure reaction, namely the forma-
tion of a M-Hg-M linkage would be probably ac-
complished by a symmetrization process of the active
tetrametallic intermediates m formed from a condensa-
tion reaction of 1 with PhHgCl (eq 2).
Lengths (Å)
Hg-Mo(1)
Mo(1)-C(10)
Mo(1)-C(15)
Mo(2)-C(2)
O(1)-C(7)
2.754(2)
2.39(1)
1.94(1)
2.34(2)
1.42(2)
1.20(2)
1.51(2)
Hg-Mo(2)
Mo(1)-C(11)
Mo(2)-C(1)
Mo(2)-C(18)
O(3)-C(15)
C(1)-C(2)
2.772(1)
2.34(1)
2.35(1)
1.93(2)
1.16(2)
1.43(2)
1.50(2)
O(5)-C(18)
C(5)-C(6)
C(6)-C(7)
Angles (deg)
171.43(4) Hg-Mo(1)-C(10)
Mo(1)-Hg-Mo(2)
Hg-Mo(1)-C(11)
Hg-Mo(1)-C(16)
Hg-Mo(2)-C(18)
Hg-Mo(2)-C(20)
86.6(4)
130.0(5)
72.4(4)
70.0(5)
112(1)
118.4(5)
71.7(5)
67.7(4)
129.9(5)
Hg-Mo(1)-C(15)
Hg-Mo(1)-C(17)
Hg-Mo(2)-C(19)
C(7)-O(1)-C(8)
Mo(1)-C(15)-O(3) 177(1)
Mo(1)-C(17)-O(2) 171(1)
Mo(2)-C(19)-O(6) 176(1)
Mo(1)-C(16)-O(4) 176(1)
Mo(2)-C(18)-O(5) 176(1)
Mo(2)-C(20)-O(7) 178(1)
To confirm the structures of such bridged complexes
and to explore the possible Lewis acid-base interactions
between mercury and oxygen atoms, an X-ray diffrac-
tion analysis for 2d was undertaken. The molecular
structure of 2d is depicted in Figure 1. Selected bond
lengths and angles are summarized in Table 1.
Exp er im en ta l Section
All reactions and manipulations were carried out under
highly purified tank nitrogen using standard Schlenk or
vacuum line techniques. Tetrahedrofuran (THF), diethyl
ether, and diglyme were distilled from sodium benzophenone
ketyl under nitrogen. Dimethyl sulfoxide (DMSO) and petro-
leum ether were dried over anhydrous CaCl2; methylene
dichloride was distilled from P2O5. All solvents were degassed
by bubbling nitrogen for about 15 min prior to use. Column
chromatography and TLC were carried out by using silica gel
of 300-400 mesh and silica gel G (10-40 µm), respectively.
M(CO)6 (M ) Cr, Mo, W) were purchased from Strem Chemi-
cals Inc., and PhHgCl was prepared according to the litera-
ture.18 IR spectra were recorded on a Nicolet FT-IR 5DX
infrared spectrophotometer. 1H NMR spectra were recorded
on a J EOL FX 90Q NMR spectrometer. Elemental analysis
and MS determinations were performed by a 240C analyzer
and HP 5988A spectrometer, respectively. Melting points were
determined on a MP-500 Yanaco micromelting point ap-
paratus.
From Figure 1 it can be seen that the structure of 2d
consists of a metal-metal skeleton Mo-Hg-Mo, a 1,1′-
(3-oxapentamethylene)dicyclopentadienyl ligand and six
carbonyls. Among six carbonyls the C(15)O(3) and
C(20)O(7) are away from the Mo-Hg-Mo skeleton,
while C(16)O(4), C(17)O(2), C(18)O(5), and C(19)O(6) are
close to the skeleton. For the former two carbonyls the
Mo-C-O bond angles are 177(1) and 178(1)°, while
those for the latter four are 171(1) and 176(1)°, respec-
tively. The Hg-Mo-C(O) bond angles for the former
two are 130.0(5) and 129.9(5)°, while those for the latter
four are in the range 67-73°. The two bond lengths of
Mo-Hg equal 2.754(2) and 2.772(1) Å, which are close
to the sum of the atomic covalent radii of molybdenum
and mercury (about 2.73 Å). The bond angle of Mo(1)-
Hg-Mo(2) is 171.43(4)°, and thus the mercury atom
coordination geometry is diagonal with no significant
departure from linearity. The geometry around each
Mo atom approximates to a square-based pyramid with
the substituted cyclopentadienyl group occupying the
apical position and is very similar to that around the
chromium, molybdenum, and tungsten atoms in com-
plexes [η5-EtC5H4(CO)3Cr]2Hg,11 [η5-C5H5(CO)3Mo]2Hg,7
[η5-EtO2CC5H4(CO)3Mo]2Hg,10 and [η5-C5H5(CO)3W]2-
P r ep a r a tion of 2a . a 100 mL three-necked flask equipped
with a stir bar, a N2 inlet tube, and serum caps was charged
with 0.86 g (3.90 mmol) of Cr(CO)6, 0.516 g (2.00 mmol) of
[NaC5H4C(O)CH2], and 25 mL of diglyme. The mixture was
refluxed for 6 h. Upon cooling of the sample to 0 °C, to the
mixture was added 1.00 g (3.20 mmol) of PhHgCl, and the new
mixture was stirred for additional 1 h. After evaporation of
(16) Wong, Y. S.; Carty, A. J .; Chieh, C. J . Chem. Soc., Dalton Trans.
1977, 1801.
(17) Chieh, C.; Seyferth, D.; Song, L.-C. Organometallics 1982, 1,
473.
(18) Seyferth, D.; Burlitch, J . M. J . Organomet. Chem. 1965, 4, 127.

1956 Organometallics, Vol. 15, No. 7, 1996
Notes
Ta ble 2. Cr ysta l Da ta a n d Deta ils of th e
Str u ctu r e Refin em en t for 2d
pure 2c as a slightly air-sensitive yellow solid, mp 180 °C (dec).
1H NMR (DMSO-d6, TMS): δ 2.88-3.12 (m, 4H, CH2CH2),
5.74-5.94 (m, 4H, â-H of Cp ring), 6.12-6.42 (m, 4H, R-H of
Cp ring) ppm. IR (KBr, disk): 1999.6 (s), 1958.6 (vs), 1876.6
empirical formula
C20H16O7HgMo2
760.81
fw
(vs, νCtO), 1679.7 (m, νCdO) cm-1
.
MS (EI, W184, Hg202) [m/z
cryst syst
space group
orthorhombic
Pbca (No. 61)
15.932(3)
19.322(4)
13.774(3)
4240(1)
(relative intensity)]: 576 [CH2C(O)C5H4WHg(CO)3+, 12.9], 332
[C5H4W(CO)3+, 1.0], 276 [C5H4W(CO)+, 12.4], 202 (Hg+, 73.2),
64 (C5H4+, 0.8). Anal. Calcd for C20H12HgO8W2: C, 25.32; H,
1.28. Found: C, 25.06; H, 1.64.
a/Å
b/Å
c/Å
V/Å3
P r ep a r a tion of 2d . The same procedure as that of 2b was
followed, but 0.492 g (2.00 mmol) of (NaC5H4CH2CH2)2O was
used instead of [NaC5H4C(O)CH2]2. Further purification of
crude product 2d by TLC with 1:1 petroleum ether/CH2Cl2 as
a developer, followed by recrystallization from 1:1 petroleum
ether/CH2Cl2, gave 0.80 g (53%) of pure 2d as a slightly air-
sensitive yellow solid, mp 81-83 °C. 1H NMR (CDCl3, TMS):
δ 2.40-2.90 (m, 4H, CH2CH2OCH2CH2), 3.36-3.92 (m, 4H,
CH2OCH2), 5.00-5.64 (m, 8H, two C5H4) ppm. IR (KBr,
disk): 1950.4 (vs), 1895.0 (vs), 1860.1 (vs, νCtO), 1113.7 (w,
Z
8
Dc/g cm-3
2.383
2848.00
84.44
Mo KR (λ ) 0.710 69 Å)
293
ω-2θ
50.0
4070 (total)
2665
272
F(000)
µ(Mo KR)/cm-1
radiation
temp/K
scan type
2θ/deg (max)
no. of reflcns measd
no. of observns (I > 3.00σ(I))
no. of variables
R; Rw
ν
CsO) cm-1. MS (EI, Mo98, Hg202) [m/z (relative intensity)]: 766
0.056; 0.054
3.14
(M+, 0.2), 476 [CH2CH2C5H4Mo(CO)3Hg+, 1.8], 448 [CH2-
CH2C5H4Mo(CO)2Hg+, 3.3], 420 [CH2CH2C5H4Mo(CO)Hg+,
0.4], 392 (CH2CH2C5H4MoHg+, 7.5), 364 (C5H4MoHg+, 2.9), 202
goodness of fit indicator
the solvent at reduced pressure the residue was subjected to
column chromatography on silica gel with THF as eluent to
give crude product 2a . Further purification of 2a by recrys-
tallization from DMSO/Et2O/CH2Cl2, followed by wash with
acetone and diethyl ether, gave 0.48 g (35%) of pure 2a as a
slightly air-sensitive yellow solid, mp 165 °C (dec). 1H NMR
(DMSO-d6, TMS): δ 2.88-3.08 (m, 4H, CH2CH2), 5.28-5.40
(m, 4H, â-H of Cp ring), 5.78-588 (m, 4H, R-H of Cp ring)
ppm. IR (KBr, disk): 2032.4 (w), 1966.8 (s), 1884.8 (vs, νCtO),
(Hg+, 66.1), 162 (C5H4Mo+, 1.5). Anal. Calcd for C20H16
HgMo2O7: C, 31.57; H, 2.12. Found: C, 31.73; H, 2.14.
-
X-r a y Str u ctu r e An a lysis of 2d . Crystals of 2d suitable
for crystallography were obtained by recrystallization from
petroleum ether/CH2Cl2 (1:1) in a refrigerator. Crystal data
and results of structural refinement were summarized in Table
2. A yellow prismatic crystal having approximate dimensions
0.2 × 0.2 × 0.3 mm was used for unit cell measurements and
intensity collection on a Rigaku AFC 7R diffractometer. The
structure was solved by direct methods (SHELXS 86)19 and
expanded using Fourier techniques. The final refinement was
accomplished by the full-matrix least-squares methods. The
non-hydrogen atoms were refined anisotropically. Data were
corrected for Lp and absorption factors. All calculations were
performed on a Micro-Vax II computer using the TEXSAN
program package.20
1671.5 (m, νCdO) cm-1. MS (EI, Cr52, Hg202) [m/z (relative inten-
sity)]: 202 (Hg+, 67.9), 200 [C5H4Cr(CO)3+, 53.7], 64 (C5H4
,
+
7.6), 52 (Cr+, 16.9). Anal. Calcd for C20H12Cr2HgO8: C, 35.07;
H, 1.77. Found: C, 34.82; H, 2.05.
P r ep a r a tion of 2b. A flask described as above was
charged with 1.01 g (4.00 mmol) of Mo(CO)6, 0.516 g (2.00
mmol) of [NaC5H4C(O)CH2]2, and 25 mL of THF. The mixture
was refluxed for 15 h. Upon cooling of the sample to 0 °C, to
the mixture was added 1.00 g (3.20 mmol) of PhHgCl, and the
new mixture was stirred for additional 1 h. After evaporation
of the solvent at reduced pressure the residue was subjected
to column chromatography on silica gel with THF as eluent
to give crude product 2b. Further purification of crude 2b by
TLC with 1:1 petroleum ether/THF as a developer, followed
by wash with diethyl ether, gave 0.86 g (56%) of pure 2b as a
slightly air-sensitive yellow solid, mp 127-129 °C. 1H NMR
(DMSO-d6, TMS): δ 2.90-3.20 (m, 4H, CH2CH2), 5.72-5.98
(4H, â-H of Cp ring), 6.12-6.46 (m, 4H, R-H of Cp ring) ppm.
IR (KBr, disk): 2007.8 (s), 1975.0 (vs), 1884.8 (vs, νCtO), 1671.5
(m, νCdO) cm-1. MS (EI, Mo98, Hg202) [m/z (relative intensity)]:
364 (C5H4MoHg+, 13.0), 274 [OCC5H4Mo(CO)2+, 10.2], 218
[C5H4Mo(CO)2+, 7.9], 202 (Hg+, 100), 190 (C5H4Mo(CO)+, 21.3),
Ack n ow led gm en t. We are grateful to the National
Natural Science Foundation of China, the Laboratory
of Organometallic Chemistry at Shanghai Institute of
Organic Chemistry, and the National Education Com-
mittee for the financial support of this work.
Su p p or tin g In for m a tion Ava ila ble: Full tables of char-
acterization data for the new compounds, text describing X-ray
procedures, and tables of crystallographic data, atomic coor-
dinates and thermal parameters, and bond lengths and angles
for 2d (11 pages). Ordering information is given on any
current masthead page.
162 (C5H4Mo+, 15.3), 98 (Mo+, 19.4). Anal. Calcd for C20H12
HgMo2O8: C, 31.09; H, 1.57. Found: C, 31.09; H, 1.64.
P r ep a r a tion of 2c. The same procedure as that of 2a was
followed, but 1.38 g (4.00 mmol) of W(CO)6 was used instead
of Cr(CO)6. Further purification of crude product 2c by
recrystallization from DMSO at -20 °C gave 0.72 g (38%) of
-
OM9508795
(19) SHELXS86: Sheldrick, G. M. In Crystallographic Computing
3; Sheldrick, G. M., Kruger, C., Goddard, R., Eds.; Oxford University
Press: Oxford, U.K., 1985; pp 175-189.
(20) TEXSAN: Crystal Structure Analysis Package; Molecular
Structure Corp.: The Woodlands, TX, 1985, 1992.