Lanthanide-transition metal carbonyl complexes: Condensation of solvent-separated ion-pair compounds into extended structures

Article abstract of DOI:10.1021/ic060756k

New solvent-separated ion-pair compounds and extended structures containing ytterbium(II)-transition metal isocarbonyl linkages were synthesized. [Yb(THF)₆][M(CO)₅]₂ (1, M = Mn; 2, M = Re) were prepared via transmetalation reactions between Yb metal and Hg[M(CO) ₅]₂ in THF. Reflux of 1 in Et₂O afforded {Yb(THF)₂-(Et₂O)₂[(μ-CO)₂Mn(CO) ₃]₂}_∞ (3) which is a sheet-layer structure. In ether solution, 3 is converted to {Yb(THF)₄-[(μ-CO) ₂Mn(CO)₃]₂}_∞ (4) which has a linear structure. In both 3 and 4, ytterbium is 8-coordinated (distorted square antiprism geometry), four coordination sites occupied by molecules of solvent and four more by oxygen atoms of isocarbonyl linkages. The [Mn(CO) ₅]^- anion has trigonal bipyramidal geometry and is linked to ytterbium through two equatorial carbonyls. The formation of two minor products, (THF)₂Mn₃(CO)₁₀ (5) and [(THF) ₅Yb(μ-CO)Mn₃-(CO)₁₃][Mn₃(CO) ₁₄] (6), was observed during condensation of 1 into 3 and 4.

Full text of DOI:10.1021/ic060756k

Inorg. Chem. 2006, 45, 10115−10125
Lanthanide−Transition Metal Carbonyl Complexes: Condensation of
Solvent-Separated Ion-Pair Compounds into Extended Structures
Pavel V. Poplaukhin, Xuenian Chen, Edward A. Meyers, and Sheldon G. Shore*
Department of Chemistry, The Ohio State UniVersity, Columbus, Ohio 43210
Received May 4, 2006
New solvent-separated ion-pair compounds and extended structures containing ytterbium(II)−transition metal
isocarbonyl linkages were synthesized. [Yb(THF)6][M(CO)5]2 (1, M
transmetalation reactions between Yb metal and Hg[M(CO)5]2 in THF. Reflux of 1 in Et2O afforded
(Et2O)2[( -CO)2Mn(CO)3]2 (3) which is a sheet-layer structure. In ether solution, 3 is converted to
[( -CO)2Mn(CO)3]2
) Mn; 2, M ) Re) were prepared via
{Yb(THF)2-
µ
}
∞
{
Yb(THF)4-
µ
}
∞
(4) which has a linear structure. In both 3 and 4, ytterbium is 8-coordinated (distorted square
antiprism geometry), four coordination sites occupied by molecules of solvent and four more by oxygen atoms of
isocarbonyl linkages. The [Mn(CO)5]- anion has trigonal bipyramidal geometry and is linked to ytterbium through
two equatorial carbonyls. The formation of two minor products, (THF)2Mn3(CO)10 (5) and [(THF)5Yb(
µ-CO)Mn3-
(CO)13][Mn3(CO)14] (6), was observed during condensation of 1 into 3 and 4.
Introduction
nation of chlorobenzenes.3c,d These catalysts have demon-
strated improved activity and selectivity over the ones
containing only the transition metal. The reason for such
improved characteristics is believed to rest in the close
interaction between the reduced lanthanide and the transition
metals produced from the mixed Ln-M precursors. The
polymeric framework of the precursor allows the uniform
distribution of the metals over a catalyst’s support surface.3a
When the precursor is reduced to bimetallic nanoparticles,
the more electropositive lanthanide can enhance the reducing
properties of the transition metal by transferring electron
density to the latter. The introduction of such catalysts could
be useful both industrially and environmentally, since
chlorobenzenes, as well as phenol, are large-scale industrial
toxins. The improved selectivity of the mixed Ln-M
catalysts is also very advantageous for the process of
conversion of phenol to cyclohexanone, because cyclohex-
anone is used to prepare caprolactam, a starting material in
the preparation of nylon 6.
The past three decades witnessed an increase of the interest
in lanthanide-transition metal (Ln-M) complexes. Apart
from fundamental research interest, such bimetallic arrange-
ments promise new and exciting opportunities for practical
applications in the fields of materials science1 and catalysis.2,3
In particular, systems containing isocyanide or isocarbonyl
linkages between the lanthanide and the transition metal offer
a wide variety of structural possibilities that still want
exploration. Isocyanide-containing Ln-M systems proved
to be precursors for superior reduced bimetallic heteroge-
neous catalysts for such important processes as aqueous
vapor-phase hydrogenation of phenol3b and hydrodechlori-
* To whom correspondence should be addressed. E-mail: shore@
chemistry.ohio-state.edu.
(1) (a) Traversa, E.; Matsushima, S.; Okada, G.; Sadaoka, Y.; Sakai, Y.;
Watanabe, K. Sens. Actuators, B 1995, 25, 661. (b) Sadaoka, Y.;
Traversa, E.; Sakamoto, M. J. Mater. Chem. 1996, 6 (8), 1355. (c)
Sakamoto, M.; Matsuki, K.; Ohsumi, R.; Nakayama, Y.; Matsumoto,
A.; Okawa, H. Bull. Chem. Soc. Jpn. 1992, 65, 2278. (d) Sadaoka,
Y.; Aono, H.; Traversa, E.; Sakamoto, M. J. Alloys Compd. 1998,
278, 135.
(2) (a) Imamura, H.; Miura, Y.; Fujita, K.; Sakata, Y.; Tsuchiya, S. J.
Mol. Catal. A 1999, 140, 81. (b) Imamura, H.; Igawa, K.; Sakata, Y.;
Tsuchiya, S. Bull. Chem. Soc. Jpn. 1996, 69, 325. (c) Imamura, H.;
Igawa, K.; Kasuga, S.; Sakata, Y.; Tsuchiya, S. J. Chem. Soc., Faraday
Trans. 1994, 90, 2119.
(3) (a) Rath, A.; Aceves, E.; Mitome, J.; Liu, J.; Ozkan, U. S.; Shore, S.
G. J. Mol. Catal. Commun. 2001, 165, 103. (b) Shore, S. G.; Ding,
E.; Park, C.; Keane, M. A. Catal. Commun. 2002, 3, 77. (c) Jujjuri,
S.; Ding, E.; Shore, S. G.; Keane, M. A. Appl. Organomet. Chem.
2003, 17, 493.
Ln-M complexes with isocarbonyl linkages also offer a
rich variety of structural combinations with the potential for
a wealth of applications. We believe that they could be
employed as sources for the preparation of perovskite-type
oxides, LnMO3, that are used as methane oxidation catalysts.4
It is also worth noting that the synthesis and characterization
of such new types of heterometallic systems have made
contributions to the realm of fundamental science, improving
our knowledge of how lanthanides and transition metals can
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Inorganic Chemistry, Vol. 45, No. 25, 2006 10115

Poplaukhin et al.
Chart 1
material, in turn, was prepared via a transmetalation reaction
between Ln metal and Hg[Co(CO)4]2 (reaction 1) . Solvent-
Yb + Hg[Co(CO)4]2 L 8 [Yb(L)6][Co(CO4)]2
(1)
-Hg
be arranged together in the presence of various ligands. New
ways to synthesize compounds that hold metals of very
different kinds in close proximity were developed.5-10
Extensive reviews on past research of Ln-M carbonyl
complexes are available.5 One can divide these complexes
into three types (Chart 1):5c (I) systems with a direct Ln-M
bond, (II) solvent-separated ion pairs, and (III) systems with
isocarbonyl linkages.
Type I compounds are the most rare among the three, and
to the best of our knowledge, only three X-ray structures
have been reported.6 Preparation techniques for these het-
erometallics include transmetalation,5a,7 metathesis,6b,8 M-M
bond cleavage (reduction of the metal carbonyl dimers in
liquid ammonia6a,c,9 or over amalgam10), adduct formation,8a,11
M-X bond cleavage,8a,12 and condensation of solvent-
separated ion pairs into extended arrays.5a,b The last approach
appears to be especially valuable because it enables the
preparation of polymeric structures with homogeneous
distribution of the lanthanide and transition metal atoms.
These materials are potentially important for preparing mixed
Ln-M catalysts.3,5 Such structures allow uniform dispersion
of the metals over the support’s surface.2a
separated ion pair compounds of the general formula [Yb(L)n]-
[Co(CO)4]2 (L ) THF, Pyr) were employed as starting
materials, leading to two-dimensional arrays upon stirring
with toluene (reaction 2). The present study continues this
[Yb(L)n][Co(CO)4]2
Tol
[(L)xYb{(µ-CO)yCo(CO)4-y}2·zTol]∞
-2Pyr 8
(2)
L ) Pyr, x ) 6y, y ) 2, z ) 0
-2THF
L ) THF, x ) 2, y ) 3, z ) 1
research, shifting the emphasis from the transition metals of
group VIII to those of group VII. Manganese-containing
catalysts are widely used for the oxidative coupling and
flameless combustion of methane,13 and it would be of
interest to prepare new types of potential catalyst precursors
for such processes. Thus, the metals we worked with were
Mn and Re.
Apart from the practical purpose of preparing new catalyst
precursors, this work also investigates the influence of the
solvent upon the products’ structures. Competition5b between
the solvent molecules and the transition metal carbonyl anion
for the Lnn+ cation takes place in solution. If the metallic
core of the anion possesses the greater electron-donating
ability, then type I compounds form; on the other hand, if
the solvent is the strongest electron donor available, then
solvent-separated ion pairs (Type II) result. Finally, oxygen
atoms of the carbonyl ligands can be electron donors through
isocarbonyl bridges with a Type III complex being produced.
Lewis basicity values are available for a wide range of
organometallic species,14 which should in principle help us
to predict the reaction’s outcome. But preliminary work
shows that such an approach is not very reliable.
Several such polymers containing Co linked to Yb or Eu
were prepared recently in this laboratory.5a,b The starting
(4) (a) Baiker, A.; Marti, P. E.; Keusch, P.; Fritsch, E.; Reiller, A. J. Catal.
1994, 146, 268. (b) Lago, R.; Bini, G.; Pina, M. A.; Fierro, J. L. G.
World Congr. Oxid. Catal., Proc., 3rd; Stud. Surf. Sci. Catal. 1997,
110, 721. (c) Yoshihko, S.; Enrico, T.; Sakamoto, M. J. Alloys Compd.
1996, 240, 51. (d) Buassi-Monroy, O. S.; Luhrs, C. C.; Chavez-Chavez,
A.; Michel, C. R. Mater. Lett. 2004, 58, 716.
(5) (a) Plecnik, C. E.; Liu, S.; Liu, J.; Chen, X.; Meyers, E. A.; Shore, S.
G. Inorg. Chem. 2002, 41, 4936. (b) Plecnik, C. E.; Liu, S.; Liu, J.;
Chen, X.; Meyers, E. A.; Shore, S. G. J. Am. Chem. Soc. 2004, 126,
204. (c) Plecnik, C. E.; Liu, S.; Shore, S. G. Acc. Chem. Res. 2003,
36, 499.
(6) (a) Deng, H.; Shore, S. G.; J. Am. Chem. Soc. 1991, 113, 8538. (b)
Beletskaya, I. P.; Voskoboynikov, A. Z.; Chuklanova, E. B.; Kirillova,
N. I.; Shestakova, A. K.; Parshina, N. I.; Gusev, A. I.; Magomedov,
G. K.-I. J. Am. Chem. Soc. 1993, 115, 3156. (c) Deng, H.; Chun,
S.-H.; Florian, P.; Grandinetti, P. J.; Shore, S. G. Inorg. Chem. 1996,
35, 3891.
(7) (a) Lin, G.; Wong, W.-T. Organomet. Chem. 1996, 522, 271. (b)
Suleimanov, G. Z.; Khandozhko, V. N.; Shifrina, R. R.; Abdullaeva,
L. T.; Kolobova, N. E.; Beletskaya, I. P. Dokl. Akad. Nauk SSSR 1984,
277, 1407.
(8) (a) Crease, A. E.; Legzdins, P. J. Chem. Soc., Dalton Trans. 1973,
1501. (b) Suleimanov, G. Z.; Beletskaya, I. P. Dokl. Akad. Nauk SSSR
1981, 261, 381. (c) Magomedov, G. K.-I.; Voskoboynikov, A. Z.;
Chuklanova, E. B.; Gusev, A. I.; Beletskaya, I. P. Metalloorg. Khim.
1990, 3, 706.
Results and Discussion
1. Transmetalation Reactions between Yb and Hg-
[M(CO)5]2 (M ) Mn, Re). Direct reactions between Yb
metal and Hg[M(CO)5]2 in various polar solvents produced
solvent-separated ion-pair species [Yb(L)n][M(CO)5]2 (M )
Mn, 1; Re, 2 reaction 3). With this approach, similar results
(9) Voskoboynikov, A. Z.; Beletskaya, I. P. Russ. Chem. Bull. 1997, 46,
1789.
(10) (a) Beletskaya, I. P.; Suleimanov, G. Z.; Shifrina, R. R.; Mekhdiev,
R. Y.; Agdamskii, T. A.; Khandozhko, V. N.; Kolobova, N. E. J.
Organomet. Chem. 1986, 299, 239. (b) White, J. P., III; Deng, H.;
Boyd, E. P.; Gallucci, J.; Shore, S. G. Inorg. Chem. 1994, 33, 1685.
(11) (a) Marks, T. J.; Kristoff, J. S.; Alich, A.; Shriver, D. F. J. Organomet.
Chem. 1971, 33, C35. (b) Crease, A. E.; Legzdins, P. J. J. Chem.
Soc., Chem. Commun. 1972, 268.
(12) Suleimanov, G. Z.; Khandozhko, V. N.; Mekhdiev R. Y.; Petrovskii,
P. V.; Yanovskaya, I. M.; Lependina, O. L.; Kolobova, N. E.;
Beletskaya, I. P. IzV. Akad. Nauk SSSR, Ser. Khim. 1988, 685.
(13) (a) Pak, S.; Qui, P.; Lunsford, J. H. J. Catal. 1998, 179, 222. (b)
Machocki, A.; Ioannides, T.; Stasinska, B.; Gac, W.; Avgouropoulos,
G.; Delimaris, D.; Grzegorczyk, W.; Paseczna, S. J. Catal. 2004, 227,
282. (c) Tsyrulnikov, P. G.; Kovalenko, O. N.; Gogin, L. L.; Starostina,
T. G.; Noskov, A. S.; Kalinkin, A. V.; Krukova, G. N.; Tsybulina, S.
V.; Kudrina, E. N.; Bubnov, A. V. Appl. Catal. A 1998, 167, 31.
(14) (a) Dessey, R. E.; Pohl, R. L.; King, R. B. J. Am. Chem. Soc. 1966,
88, 5121. (b) King, R. B. Acc. Chem. Res. 1970, 3, 417.
10116 Inorganic Chemistry, Vol. 45, No. 25, 2006

Lanthanide-Transition Metal Carbonyl Complexes
Hg[M(CO)5]2 + Yb
L8 [Yb(L)n][M(CO)5]2 + Hg
Table 1. Infrared Data in the Carbonyl Stretching Frequency Region
9
(3)
compound
Mn2(CO)10
medium
ν )
CO (cm-1
1, M ) Mn, L ) THF, n ) 6
2, M ) Re, L ) THF, n ) 6
1a, M ) Mn, L ) DME, n not established, presumably 415
1b, M ) Mn, L ) DMF, n not established15
THF or Et2O
2045 (m, sh), 2008 (s, sh),
1980 (m, sh)
Re2(CO)10
KMn(CO)5
THF or Et2O
THF
2070 (m, sh), 2009 (s, sh),
1966 (m, sh)
2012 (vw), 1899 (s),
1865 (s), 1835 (m), 1896 (s),
1862 (s), 1830 (m)a
Pyr
THF
1978 (vw), 1897 (s), 1861(s)
2010 (vw), 1968 (w), 1910 (s)
1863 (s), 1830 (m), 1911 (s),
1864 (s), 1835 (sh)a
1c, M ) Mn, L )
NaRe(CO)5
pyridine, n not established, presumably 615
Pyr
2009 (w), 1968 (mw), 1913 (s),
1860 (vs)
were obtained for trivalent lanthanides with a number of
transition metal anions,5,7 and for divalent lanthanides with
[Co(CO)4]-.5 Despite a vast difference in Lewis basicity
([Mn(CO)5]-, 77; [Re(CO)5]-, 2.5 × 104; compared to the
nucleophilicity of [Co(CO)4]-, which is set arbitrarily as 1)14
and the softer Lewis acidic nature of Yb2+ compared to Yb3+,
the products are still ion-paired compounds with no isocar-
bonyl linkages formed. Anions [M(CO)5]- (M ) Mn, Re),
were unable to penetrate the coordination sphere of solvent
around the Yb2+ cation to replace THF molecules in their
role as Lewis base. It has been shown16 that the Lewis
basicities of [Co(CO)4]- and THF are similar (i.e., the
basicity of THF should only slightly exceed 1). According
to the results of Dessy et al.14, it is inferior to values for
anions studied herein. Our results suggest that an approach
in which the electrophilic center (Yb2+ in this case) binds to
the strongest Lewis base available5,16 is not sufficient to
predict what ligands will coordinate to the Yb2+ cation first.
Compounds with similar structure were synthesized by
reduction of metal carbonyl dimers with lanthanide amal-
gam.10 Using the methods described herein, we carried out
the reduction of Mn2(CO)10 (but not that of Re2(CO)10) with
ytterbium amalgam in THF and found that the product from
this reaction is identical to 1 [Yb(THF)6][Mn(CO)5]2 (reaction
4). Having established that, we routinely employed this
Hg[Mn(CO)5]2
Hg[Re(CO)5]2
KBr
2065 (s), 1995 (s, sh), 1955 (vs),
645(m),b
2067 (s), 2008 (sh),1975 (vs)c
2073 (ms), 2014 (w, sh),
1974 (vs), 1935 (m, sh)d
2075 (ms), 2024 (ms), 1995 (vs)d
2011 (m to s), [1918 (s), 1892 (s),
1865 (m)], 1760 (ms)
Nujol
CH2Cl2
THF
1
2
THF
2043 (w), 2011 (s), 1972 (m),
1935 (s), 1890 (m), 1754 (m)
2012 (m), [1897 (s), 1864 (s)]
2014 (vw), [1898 (s), 1865 (s)]
1978 (vw), [1897 (s), 1861 (s)]
2015 (m), [1929 (s), 1903 (s)],
1724 (ms)
1a
1b
1c
DME
DMF
Pyr
Et2O
3
Et2O
2015 (s, sh), 1931 (mw),
1908 (mw), 1707 (mw)
a Ellis, J. E.; Flom, E. A. J. Organomet. Chem. 1975, 99, 263. b Burlitch,
J. M. Chem. Commun. 1968, 887. c Hieber, W.; Schropp, W., Jr. Chem.
Ber. 1960, 93, 455. d Hsieh, A. T. T.; Mays, M. J. J. Chem. Soc. (A) 1971,
2648.
separating the products from the black material. Metallic
mercury also precipitated along with the products, to produce
a homogeneous mixture. For these reasons, no solid-state
IR or elemental analyses were attempted. Upon removal of
the original solvent and dissolution of the precipitates in THF,
the IR spectra were like those of 1 and 2, [Yb(THF)6]-
[M(CO)5]2. It is reasonable to assume some polymeric
structures were formed in toluene and ether and cleaved later
when THF was added to them.
Yb/Hg + Mn2(CO)10 THF8 [Yb(THF)6][Mn(CO)5]2 (4)
Solution IR Spectra of [Yb(THF)6][Mn(CO)5]2 (1), [Yb-
(THF)6][Re(CO)5]2 (2), [Yb(DME)n][Mn(CO)5]2 (1a), [Yb-
(DMF)n][Mn(CO)5]2 (1b), and [Yb(pyr)6][Mn(CO)5]2 (1c).
The IR spectra of compounds 1 and 1a (Table 1) reveal
features typical for solvent-separated ion-pair species. A
thorough discussion of how such characteristic patterns arise
can be found in the literature.5a,16 In each spectrum, three
groups of peaks can be clearly seen. The central group (in
square parentheses in Table 1) strongly resembles the
spectrum of the corresponding pure17 [M(CO)5]- anion in
pyridine. These absorbances are assigned to the isolated
transition metal carbonylate anion as it exists in solution of
ligand. For 1, this group is shifted to higher frequencies by
about 5 cm-1 compared to the “pure” anion, suggesting that
procedure to synthesize 1.
Syntheses analogous to reaction 3 were also carried out
in diethyl ether and toluene. Earlier, a similar approach using
Hg[Co(CO)4]2 yielded the previously unknown cluster5b
[Co4(CO)11]2-. In the present study, in both solvents, some
reaction occurred as shown by a solution color change, and
precipitation of a homogeneous mixture of product and a
finely divided black powder. Unfortunately, the precipitates
were only sparingly soluble, precluding the possibility of
(15) For 1a and 1c, the assignment of values of n was done by analogy
with known complexes where cations [Yb(DME)4]2+ and [Yb(pyr)6]2+
are present.5a Elemental analysis was performed for 1c indicating the
presence of four pyridine molecules in the structure, but most probably
some of the coordinated ligands were lost during sample preparation.
In the case of 1b, no data suggesting the number of DMF ligands
coordinated around the Yb2+ center is available, but solution IR data
clearly suggest that this is a solvent-separated ion-pair compound.
(16) (a) Edgell, W. F.; Yang, M. T.; Koizumi, N. J. Am. Chem. Soc. 1965,
87, 2563. (b) Edgell, W. F.; Lyford, J. IV; Barbetta, A.; Jose, C. I. J.
Am. Chem. Soc. 1971, 93, 6403; Edgell, W. F.; Lyford, J. IV J. Am.
Chem. Soc. 1971, 93, 6407. (c) Darensbourg, M. Y. Prog. Inorg. Chem.
1985, 33, 221.
(17) By the solution IR spectrum of the pure metal pentacarbonyl anion,
we mean the spectrum which was recorded in strongly coordinating
solvent, such as pyridine or DMF. Those solvents bind tightly to the
cation and preclude any interaction between it and the carbonyl ligands
of the anion, so that the latter’s geometry is unaffected. Compare the
spectra of 1, 1c, and KMn(CO)5 in pyridine, Table 1.
Inorganic Chemistry, Vol. 45, No. 25, 2006 10117

Poplaukhin et al.
some extra electron density is drained from the anion,
probably through weak (S)nYb‚‚‚OCM(CO)4 interaction.5a,18
For 1a, the position of this group coincides with the
[Mn(CO)5]- spectrum, but an extra band appears on the left,
which is discussed later. The spectra of 1b and 1c coincide
entirely with the pure anion spectrum, with no extra peaks
emerging. This is attributed to the very high Lewis basicities
of pyridine and DMF, which enables them to bind to the
Yb2+ cation strongly. Another two groups of peaks appear
on the right and left sides of the central group. Their
appearance can be accounted for in terms of formation of
contact ion pairs.5a,16 The IR spectrum of 2 is more
complicated than that of 1, but it can be analyzed along the
same lines.
The difference in the spectra of 1c in pyridine and in Et2O
is of interest. The compound was synthesized in pyridine,
and its spectrum coincides completely with that of Na[Mn-
(CO)5] in the same solvent. However, when pyridine is
removed and Et2O added, the IR spectrum is very much like
the spectra of 1, 1a, and 2, with three distinct groups of
peaks, indicating that contact ion pairs are present in solution.
Both the pyridine solution and the Et2O solution are dark
brown, from which we conclude that even in ether solution
some pyridine molecules are retained around the Yb2+ cation,
but because some exchange occurs, the solvation layer is no
longer impermeable, and an interaction between the ion pairs
takes place.
Figure 1. Molecular structure of 1: (a) the [Yb(THF)6]2+ cation (25%
thermal ellipsoids) and (b) the [Mn(CO)5]- anion (15% thermal ellipsoids).
X-ray Structures of 1 and 2. X-ray data were collected
at -73 °C. Structures of the anions of these salts are
represented in Figures 1 and 2. Because the [Yb(THF)6]2+
cation is essentially the same for both complexes, its structure
is shown only once (Figure 1a). Crystallographic data and
selected bond distances and angles are given in Tables 2
and 3. The [Yb(THF)6]2+ cation closely resembles its
counterpart in the tetracarbonylcobaltate salt.5 In both
structures, two independent ytterbium atoms reside on
inversion centers, each with three independent THF ligands;
additional THF ligands are generated by symmetry trans-
formations, resulting in nearly octahedral coordination of the
Yb(II) centers. In 1, the average Yb-O bond lengths are
2.392(4) and 2.391(6) Å; in 2, these are 2.389(7) and 2.392(8)
Å. In both structures, there is disorder indicated in the carbon
atoms of the THF ligands. This cation, as reported else-
where,5 has Yb-O distances of 2.282(2), 2.387(2), and
2.396(3) Å. A shorter distance (2.298 Å) was reported for
[Yb(THF)6][(nido-7,8-C2B9H11)2].19 Other Yb(II) compounds
with coordinated THF ligands and their Yb-O bond lengths5
include [(MeOCH2CH2C5H4)2Yb(THF)] (2.496(4) Å),20a
Cp*2Yb(THF) (2.412(5) Å),20b (MeC5H4)2Yb(THF) (2.53(2)
Å),20c and [{Yb(TptBu,Me)(THF)(µ-CO)2Mo(η5-C5H4Me)-
(CO)3}2] (2.510(3) Å).20d For comparison, the Yb-O dis-
Figure 2. [Re(CO)5]- anions in 2 (25% thermal ellipsoids): (a) anion
without disorder and (b) disordered anion.
tances in [Yb(DIME)3][Co(CO)4]2 (Yb 9-coordinated, tri-
capped trigonal arrangement) are from 2.49(1) to 2.69(2)
Å.10b
The manganese pentacarbonyl anion of 1 is similar to the
same anion in other salts.21 The structure contains two
crystallographically independent anions, one of which is
ordered and one disordered (see Supporting Information).
In ordered Mn(CO)5, the average Mn-C bond length is
1.795(9) Å, and the average C-O bond length is 1.155(8)
Å.
(18) Boncella, J. M.; Andersen, R. A. Inorg. Chem. 1984, 23, 432.
(19) Manning, M. J.; Knobler, C. B.; Khatter, R.; Hawthorne, M. F. Inorg.
Chem. 1991, 30, 2009.
(20) (a) Deng, D.; Qian, C.; Song, F.; Wang, Z.; Wu, G.; Zheng, P. J.
Organomet. Chem. 1993, 443, 79. (b) Tilley, T. D.; Andersen, R. A.;
Spencer, B.; Ruben, H.; Zalkin, A.; Templeton, D. H. Inorg. Chem.
1980, 19, 2999. (c) Zinnen, H. A.; Pluth, J. J.; Evans, W. J. J. Chem.
Soc., Chem. Commun. 1980, 810. (d) Hillier, A. C.; Sella, A.; Elsegood,
M. R. J. Chem. Soc., Dalton Trans. 1998, 3871.
We could find no record in the Cambridge X-ray Structure
Database describing the [Re(CO)5]- anion. It is reasonable
(21) (a) Frenz, B. A.; Ibers, J. A. Inorg. Chem. 1972, 11, 1109. (b) Corraine,
M. S.; Lai, C. K.; Zhen, Y.; Churchill, M. R.; Buttrey, L. A.; Ziller,
J. W.; Atwood, J. D. Organometallics 1992, 11, 35. (c) Kong, G.;
Harakas, G. N.; Whittlesey, B. R. J. Am. Chem. Soc. 1995, 117, 3502.
10118 Inorganic Chemistry, Vol. 45, No. 25, 2006

Lanthanide-Transition Metal Carbonyl Complexes
Table 2. Crystallographic Data for [Yb(THF)6][M(CO)5]2 (1, M ) Mn; 2, M ) Re), {Yb(THF)2(Et2O)2(Mn(CO)5)2}∞ (3), and
{Yb(THF)4(Mn(CO)5)2}∞ (4)
1
2
3
4
empirical formula
fw
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
C34H48O16Mn2Yb
995.64
P1h
C34H48O16Re2Yb
1258.16
P1h
C26H36O14Mn2Yb
855.47
C2/c
16.7913(10)
10.3795(10)
19.6009(10)
90
93.357(10)
90
3410.2(4)
4
C26H32Mn2O14Yb
851.44
C2/c
11.3065(10)
18.9475(10)
15.6224(10)
90
95.881(10)
90
3329.2(4)
4
10.8799(10)
11.1321(10)
19.5728(10)
78.261(10)
89.715(10)
68.699(10)
2156.3(3)
2
10.0421(10)
10.7667(10)
19.7414(10)
94.585(10)
92.613(10)
92.898(10)
2122.3(3)
2
Z
D
calcd (g cm-3
)
1.533
1.969
1.666
1.699
T (°C)
-73
-73
-73
-73
µ (mm-1
)
2.790
7.939
3.509
3.594
R1[I > 2σ(I)]a
R2 (all data)b
GOF on F2
0.0375
0.1053
1.029
0.0517
0.1400
1.076
0.0443
0.1052
1.020
0.0362
0.0870
1.058
a R1 ) ∑||F0| - |Fc||/∑|F0|. b R2 ) {∑w(F0 - Fc )2/∑w(F0 )2}1/2
.
2
2
2
Table 3. Selected Bond Distances (Å) and Angles (deg) for
[Yb(THF)6][M(CO)5]2 (1, M ) Mn; 2, M ) Re)a
one previously known example of a pentacarbonyl transition
metal anion with square pyramidal geometry,24 the [Mn(CO)5]-
anion in the complex [Ph4P][Mn(CO)5].
1
2
Condensation of 1 with Et2O into Extended Structures
{Yb(THF)2(Et2O)2[(µ-CO)2Mn(CO)3]2}∞ (3) and {Yb-
(THF)4[(µ-CO)2Mn(CO)3]2}∞ (4). It has been shown that
dissolution of [Ln(S)6][Co(CO)4]2 (S ) THF, pyridine) in
diethyl ether and toluene facilitates condensation of solvent-
separated ion pairs into extended linear structures or two-
dimensional arrays where the cation and the anion are linked
together by isocarbonyl bridges.5 In diethyl ether, novel
cobalt clusters that are still bonded to the lanthanide moiety
through bridging isocarbonyls were obtained.5b We carried
out similar reactions on salts 1 and 2. Condensation with
ether, but not with toluene, proved to be possible for 1
(reaction 5),
Yb(1)-O(11)
Yb(1)-O(12)
Yb(1)-O(13)
Yb(2)-O(14)
Yb(2)-O(15)
Yb(2)-O(16)
M(1)-C(1)
M(1)-C(2)
M(1)-C(3)
M(1)-C(4)
M(1)-C(5)
C(2)-O(2)
C(4)-O(4)
C(1)-O(1)
C(3)-O(3)
C(5)-O(5)
2.400(4)
2.385(4)
2.392(4)
2.388(4)
2.390(4)
2.394(4)
1.829(8)
1.775(9)
1.797(8)
1.778(8)
1.796(9)
1.160(9)
1.163(8)
1.143(8)
1.153(8)
1.154(8)
Yb(1)-O(11)
Yb(1)-O(12)
Yb(1)-O(13)
Yb(2)-O(14)
Yb(2)-O(15)
Yb(2)-O(16)
M(1)-C(1)
M(1)-C(2)
M(1)-C(3)
M(1)-C(4)
M(1)-C(5)
C(2)-O(2)
C(4)-O(4)
C(1)-O(1)
C(3)-O(3)
C(5)-O(5)
2.392(7)
2.390(7)
2.384(7)
2.405(8)
2.383(7)
2.388(6)
1.971(13)
1.932(14)
1.966(14)
1.935(12)
1.941(12)
1.154(14)
1.175(15)
1.141(14)
1.157(15)
1.138(13)
O(12)-Yb(1)-O(13)
O(11)-Yb(1)-O(12)
O(11)-Yb(1)-O(13)
C(1)-M(1)-C(3)
C(2)-M(1)-C(4)
C(2)-M(1)-C(5)
C(4)-M(1)-C(5)
C(3)-M(1)-C(2)
C(3)-M(1)-C(4)
C(3)-M(1)-C(5)
89.46(13) O(12)-Yb(1)-O(13)
89.76(15) O(11)-Yb(1)-O(12)
89.29(14) O(11)-Yb(1)-O(13)
178.5(3)
116.9(4)
121.2(4)
121.9(4)
90.0(4)
90.5(3)
89.8(3)
88.3(3)
89.8(3)
89.7(3)
175.6(6)
118.1(7)
116.8(5)
124.9(6)
94.7(5)
92.1(6)
88.1(5)
Et2O
[Yb(THF)6][Mn(CO)5]2
1-2 days8
C(1)-M(1)-C(3)
C(2)-M(1)-C(4)
C(2)-M(1)-C(5)
C(4)-M(1)-C(5)
C(3)-M(1)-C(2)
C(3)-M(1)-C(4)
C(3)-M(1)-C(5)
1
{(THF)2(Et2O)2Yb[(µ-CO)2Mn(CO)3]2}∞
(5)
3
which is poorly soluble in Et2O; however, after the mixture
was stirred overnight, a green solution was obtained, and a
vast quantity of undissolved material remained in the reaction
flask. Emerald-green crystals grown from this solution,
compound 3, have a sheet structure, as elucidated by single-
crystal X-ray analysis (Figures 3 and 4). These crystals had
to be grown relatively rapidly, taking no more than 2 days
to evaporate the solvent. When the original solution was
allowed to spend some time in the flask, or evaporated more
slowly (7-10 days), some black decomposition products
precipitated, and the solution gradually changed from green
a Data for the nondisordered [M(CO)5]- anions are given.
to assume that this anion would be analogous to [Mn(CO)5]-.
In the structure of 2, there are also two [Re(CO)5]- anions,
one of them possessing trigonal bipyramidal geometry,
analogous to that of [Mn(CO)5]- (Figure 2a), and the other
distorted and disordered (see Supporting Information). The
average Re-C distance is 1.949(14) Å, and that of C-O is
1.153(15) Å. All angles are close to the values for a trigonal
bipyramid, and the axial bond distances appear to be longer
than the equatorial ones (Table 3).
Normally, transition metal pentacarbonyls possess trigonal
bipyramidal coordination, as observed for isoelectronic
[M(CO)5]2- (M ) Cr, Mo, W),22 [Mn(CO)5]-, and Fe(CO)5.23
Angles between base ligands vary from 81.0(10) to 89.1(10)°,
and those between axial and base ligands vary from 95.3(12)
to 113.7(11)°. To the best of our knowledge, there is only
(22) (a) Kaska, W. C. J. Am. Chem. Soc. 1968, 90, 6340. (b) Anastassiou,
A. G.; Elliot, R. L.; Reichmanis, E. J. Am. Chem. Soc. 1974, 96, 7825.
(c) Darensbourg, M. Y.; Slater, S. J. Am. Chem. Soc. 1981, 103, 5914.
(d) Maher, J. M.; Beatty, R. P.; Cooper, N. J. Organometallics 1985,
4, 1354.
(23) (a) Hanson, A. W. Acta Crystallogr. 1962, 15, 930. (b) Donohue, J.;
Caron, A. Acta Crystallogr. 1964, 17, 663.
(24) Seidel, R.; Schautz, B.; Henkel, G. Angew. Chem., Int. Ed. Engl. 1996,
35, 1710.
Inorganic Chemistry, Vol. 45, No. 25, 2006 10119

Poplaukhin et al.
Figure 4. Views of a portion of the 2-D polymeric sheet of 3: (a) top
view (along the c axis) and (b) cross-section (view along b axis). Ytterbium
atoms shown in red, manganese in green, carbon in gray, and oxygen in
blue.
Figure 3. Molecular structure of 3: (a) asymmetric unit (25% thermal
ellipsoids) and (b) eight-member ring.
to yellow and yellow crystals of 4, {Yb(THF)4[(µ-CO)2Mn-
(CO)3]2}∞, appeared (reaction 6). The latter compound is a
Et2O
[Yb(THF)6][Mn(CO)5]2
7-10 days8
1
{(THF)4Yb[(µ-CO)2Mn(CO)3]2}∞
(6)
4
chain (Figure 5).
A freshly prepared solution of 1 in Et2O, upon standing
at room temperature, is noticeably converted to 3, the IR
spectrum of which consists of one strong sharp absorption
in the terminal carbonyl region, 2015 cm-1, and three
medium to weak bands at 1931, 1908, and 1707 cm-1. In
24 h, the peak at 2015 cm-1 remains almost as strong, while
the intensity of the others diminishes significantly. After more
time (4-6 days), two new peaks begin to emerge at 2046
and 1978 cm-1. This new spectrum corresponds to the
spectrum of Mn2(CO)10, with crystals of 4 growing simul-
taneously with formation of the Mn2(CO)10, and a black
powder.
Figure 5. Molecular structure of 4: (a) asymmetric unit (25% thermal
ellipsoids), (b) a diamond (15% thermal ellipsoids), and (c) portion of a
1-D linear chain of 4 (only oxygen atoms of THF ligands are shown for
clarity)
added to Et2O, some THF ligands dissociate from the Yb2+
core, leaving coordination sites vacant for other Lewis bases.
Those vacant sites are then filled with oxygen atoms of
[Mn(CO)5]- and Et2O, thus forming diamond-shaped clusters
that combine to form crystals of 3 (Figures 3-4). The clusters
contain both THF and Et2O as ligands coordinated to the
cation. However, complex 3 is unstable in Et2O. It slowly
The following pathways for formation of 3 and 4 are
proposed. It is reasonable to assume that when complex 1 is
10120 Inorganic Chemistry, Vol. 45, No. 25, 2006

Lanthanide-Transition Metal Carbonyl Complexes
Table 4. Selected Bond Lengths (Å) and Angles (deg) for
{Yb(THF)2(Et2O)2[(µ-(CO)2Mn(CO)3)2]}∞ (3) and
{Yb(THF)4[(µ-(CO)2Mn(CO)3)2]}∞ (4)
converts to complex 4 (Figure 5), a reaction in which
[Mn(CO)5]- is oxidized to form Mn2(CO)10. In addition to
the oxidation of [Mn(CO)5]-, it is believed that Yb2+ is
reduced to Yb0, which precipitates as the black powder
described previously. Earlier, we observed that the solvent-
separated ion pairs5b [Ln(THF)6][Co(CO)4] (Ln ) Yb, Eu,
x ) 6), when placed in Et2O, undergo reactions in which
[Co(CO)4]- is oxidized to form the previously unreported
cluster [Co4(CO)11]- that is linked to the lanthanide through
isocarbonyl linkages. As in the present case, a black powder
is also produced that is attributed to the formation of the
reduced lanthanide. Unfortunately, this finely divided powder
is dispersed thoughout the polymeric sample and, as in the
present case, could not be separated from it for positive
identification of Ln0.
3
4
Mn(1)-C(1)
Mn(1)-C(2)
Mn(1)-C(3)
Mn(1)-C(4)
Mn(1)-C(5)
C(1)-O(1)
1.836(9)
1.834(9)
1.800(9)
1.759(8)
1.777(8)
1.117(8)
1.136(9)
1.164(9)
1.179(8)
1.165(8)
2.470(4)
2.473(5)
2.502(5)
2.486(5)
Mn(1)-C(1)
Mn(1)-C(2)
Mn(1)-C(3)
Mn(1)-C(4)
Mn(1)-C(5)
C(1)-O(1)
C(2)-O(2)
C(3)-O(3)
C(4)-O(4)
C(5)-O(5)
Yb(1)-O(6)
Yb(1)-O(7)
Yb(1)-O(4)
Yb(1)-O(5)
1.823(6)
1.810(7)
1.830(6)
1.773(4)
1.775(4)
1.183(15)
1.197(15)
1.138(7)
1.169(5)
1.168(5)
2.456(3)
2.468(3)
2.507(3)
2.521(3)
C(2)-O(2)
C(3)-O(3)
C(4)-O(4)
C(5)-O(5)
Yb(1)-O(11)
Yb(1)-O(21)
Yb(1)-O(4)
Yb(1)-O(5)
C(2)-Mn(1)-C(1)
C(5)-O(5)-Yb(1)
C(4)-O(4)-Yb(1)
177.5(4)
158.8(6)
159.4(5)
C(2)-Mn(1)-C(3) 179.1(3)
C(5)-O(5)-Yb(1) 174.8(4)
C(4)-O(4)-Yb(1) 173.5(4)
A reviewer of this manuscript does not accept this
interpretation arguing that Mn(CO)5- is insufficiently reduc-
ing to form Ln(0) in its conversion to Mn2(CO)10; however,
we respectfully disagree. We are reluctant to assign the black
powder observed in this and in the reactions of [Co(CO)4]-
with lanthanides5 to degradation processes and side reactions.
Another possibility that has been suggested for the
formation of Mn2(CO)10 and the black powder from
[Mn(CO)5]- is the disproportionation of [Mn(CO)5]- to Mn2-
(CO)10 and Mn. However, we believe this possiblity to be
remote. We are unaware of [Mn(CO)5]- normally undergoing
spontaneous disproportionation to give Mn and Mn2(CO)10.
If the [Mn(CO)5]- disproportionates when the THF is
replaced by Et2O, then Yb2+ is an “innocent bystander”, and
another anion is required to compensate for the excess Yb2+
when [Mn(CO)5]- is oxidized and condensed to Mn2(CO)10.
Furthermore, since manganese is in the minus one oxidation
state in [Mn(CO)5]-, the formation of metallic Mn from
[Mn(CO)5]- involves oxidation rather than reduction, and
then the question remains, what has been reduced? We
believe it to be Yb2+. It is well-known in coordination
chemistry that the stability of the oxidation state of a metal
can depend on the base strengths of the associated ligands.
The weaker basicity of Et2O compared to THF would present
a weaker barrier for electron transfer to Yb2+ than THF.
Diethyl ether is a significantly weaker base than THF. For
example, Et2O does not cleave the bridge system of B2H6,
while THF readily reacts with B2H6 to form THF‚BH3.
The redox reaction 7 can be written as decomposition of
O(11)-Yb(1)-O(11) 109.6(2)
O(21)-Yb(1)-O(21) 111.4(2)
O(6)-Yb(1)-O(6)
O(7)-Yb(1)-O(7)
93.50(19)
90.48(15)
O(4)-Yb(1)-O(4)
O(11)-Yb(1)-O(4)
O(21)-Yb(1)-O(5)
119.3(3)
72.60(16) O(6)-Yb(1)-O(4)
72.40(18) O(7)-Yb(1)-O(4)
O(4)-Yb(1)-O(4) 138.32(18)
72.35(13)
74.49(12)
The attempted analytical confirmation of the stoichiometry
of reaction 8 encountered certain difficulties. First, 3 proved
to be difficult to redissolve in Et2O, no doubt because of its
polymeric nature. Also, both 4 and the Yb metal precipitate
required separation that led to loss of products and greater
experimental errors. Despite this, determination of the
amount of ytterbium produced in reaction 8 was found to
correspond approximately to what is expected from the
proposed process’s stoichiometry.27 That, along with the fact
that solution IR of the mother liquor of 4 reveals the presence
of Mn2(CO)10, confirming the oxidation of [Mn(CO)5]-.
Molecular Structure of 3. The structure is represented
in Figures 3 and 4. Crystallographic data are given in Table
2; selected bond distances and angles are given in Table 4.
In the structure of 3, half of an Yb atom, two ligands (THF
and Et2O, Figure 3a), and one manganese pentacarbonylate
anion form the asymmetric unit. Symmetry transformations
of these unique atoms generate a nonplanar polymeric sheet
(Figure 4a). The axial “poles” (constructed of the two axial
carbonyls and the manganese atom) of the two manganese
pentacarbonylate anions attached to the same ytterbium atom
are almost exactly perpendicular to each other. In 3, four
Yb2+ + 2[Mn(CO)5]- Et2O8 Yb0 + Mn2(CO)10
(7)
(25) http://www.webelements.com/webelements/elements/text/Yb/
red.html
(26) (a) Dessy, R. E.; Weissman, P. M.; Pohl, R. L. J. Am. Chem. Soc.
1966, 88, 5117. (b) Corraine, M. S.; Atwood, J. D. Organometallics
1991, 10, 2315. (c) Pugh, J. R.; Meyer, T. J. J. Am. Chem. Soc. 1992,
114, 3784.
3 to 4 (reaction 8). The fact that it takes more time to form
(27) Two hundred forty milligrams of 3 was dissolved in 50 mL of diethyl
ether, and the solution was allowed to sit in the flask for 7 days. A
black precipitate appeared, along with the crystals of 4. The remaining
solution was then removed, and the precipitate was washed with THF
to separate ytterbium metal (compound 4 dissolves in THF, apparently
producing 1). Sixty-nine milligrams of the black material was collected.
The analysis performed by Galbraith Laboratories, Inc., showed
42.42% ytterbium content, which amounts to 29.3 mg of ytterbium
metal. On the basis of stoichiometry of reaction 8, 24.2 mg is expected.
The explanation of this difference could possibly be that not all of
the 4 was washed off, thus contributing to ytterbium content of the
sample.
Et O8
2
2{(THF)2(Et2O)2Yb[(µ-CO)2Mn(CO)3]2}∞
3
{(THF)4Yb[(µ-CO)2Mn(CO)3]2}∞
+
4
Yb + 1/2 Mn2(CO)10 + 4Et2O (8)
crystals of 4 suggests that it is a thermodynamic product,
while the structure of 3 is a kinetic one.
Inorganic Chemistry, Vol. 45, No. 25, 2006 10121

Poplaukhin et al.
Table 5. Selected Bond Distances (Å) and Angles (deg) for
[(THF)5Yb(µ-CO)Mn3(CO)13][Mn3(CO)14] (6)
diamonds’ connection points. Each diamond is planar, with
its plane perpendicular to the planes of its two neighbors
(Figure 5c). The four THF ligands are located around the
Yb2+ cation according to the principle of least repulsion, thus
lying on bisectors of dihedral angles formed by the plane of
one diamond and the edge of another. The C-O-Yb angles
(174.8(4) and 173.5(4)°) are closer to 180° than correspond-
ing angles in 3, suggesting the greater stability of structure
4.
The Yb2+ center in both structures 3 and 4 is 8-coordinated
and possesses a distorted square-antiprism geometry. The
Yb1 atom lies on a 2-fold rotation axis. The vertexes of the
square antiprism are occupied by oxygen atoms of alternating
ligand molecules and [Mn(CO)5]- anions. In 3, the Yb-
O(THF) and Yb-O(Et2O) distances are 2.470(4) and 2.473(5)
Å, respectively; in 4, the Yb-O(THF) bond lengths are
2.456(3) and 2.468(3) Å. In both compounds, the Yb-
O(THF) bonds are about the same length and are longer then
those in 1 and 2: this is believed to be caused by donation
of some electron density from the manganese pentacarbon-
ylate anion to ytterbium.5,18 Each anion is bound to two
Yb(II) centers through two of its equatorial carbonyls. The
C-O distances of the bridging ligands (3, 1.179(8) and
1.165(8) Å; 4, 1.169(5) and 1.168(5) Å) are greater than those
of nonbridging equatorial carbonyls (3, 1.164(9) Å; 4,
1.183(15) Å) and three of the four axial ligands (3, 1.118(8)
and 1.136(9) Å; 4, 1.197(15) and 1.138(7) Å). In both
structures, the C-Mn-C angles deviate slightly from perfect
trigonal bipyramidal geometry. Some disorder is observed
carbonyl and THF ligands in this structure (see Supporting
Information).
Yb(1)-O(5)
Yb(1)-O(6)
Yb(1)-O(7)
Yb(1)-O(8)
O(24)-Yb(1)
Mn(1)-Mn(2)
Mn(3)-Mn(4)
Mn(1)-C(11)
Mn(1)-C(12)
Mn(1)-C(13)
Mn(1)-C(14)
Mn(1)-C(15)
Mn(2)-C(21)
Mn(2)-C(22)
Mn(2)-C(23)
Mn(2)-C(24)
C(11)-O(11)
C(12)-O(12)
C(13)-O(13)
2.378(4)
2.369(3)
2.382(4)
2.383(4)
2.437(4)
2.8841(7)
2.9023(7)
1.828(6)
1.801(6)
1.837(5)
1.824(5)
1.834(5)
1.826(7)
1.829(7)
1.837(6)
1.790(6)
1.140(6)
1.147(6)
1.136(5)
C(14)-O(14)
C(15)-O(15)
C(21)-O(21)
C(22)-O(22)
C(23)-O(23)
C(24)-O(24)
Mn(3)-C(31)
Mn(3)-C(32)
Mn(4)-C(41)
Mn(4)-C(42)
Mn(4)-C(43)
Mn(4)-C(44)
Mn(4)-C(45)
C(31)-O(31)
C(32)-O(32)
C(41)-O(41)
C(42)-O(42)
C(43)-O(43)
C(44)-O(44)
C(45)-O(45)
1.143(5)
1.148(6)
1.151(8)
1.145(8)
1.137(7)
1.171(7)
1.829(5)
1.828(5)
1.837(5)
1.842(5)
1.839(5)
1.842(5)
1.810(5)
1.148(5)
1.147(5)
1.144(6)
1.141(6)
1.144(6)
1.141(5)
1.140(5)
Mn(1)#1-Mn(2)-Mn(1) 172.62(4) C(24)-Mn(2)-C(21) 179.5(3)
C(11)-Mn(1)-Mn(2)
C(12)-Mn(1)-Mn(2)
C(13)-Mn(1)-Mn(2)
C(14)-Mn(1)-Mn(2)
C(15)-Mn(1)-Mn(2)
C(21)-Mn(2)-Mn(1)
C(22)-Mn(2)-Mn(1)
C(23)-Mn(2)-Mn(1)
C(24)-Mn(2)-Mn(1)
C(15)-Mn(1)-C(11)
C(12)-Mn(1)-C(11)
88.3(2)
C(22)-Mn(2)-C(21) 88.2(3)
174.22(16) C(45)-Mn(4)-Mn(3) 178.00(15)
83.25(15) C(41)-Mn(4)-Mn(3) 83.43(16)
78.58(15) C(42)-Mn(4)-Mn(3) 83.52(15)
87.43(17) C(43)-Mn(4)-Mn(3) 85.76(16)
86.35(2) C(44)-Mn(4)-Mn(3) 82.11(14)
90.42(2) C(31)-Mn(3)-Mn(4) 90.60(14)
89.50(2) C(41)-Mn(4)-C(42) 166.9(2)
93.66(2) C(41)-Mn(4)-C(43) 90.4(2)
89.4(2)
94.4(3)
C(41)-Mn(4)-C(44) 90.7(2)
C(32)-Mn(3)-C(31) 89.6(2)
ytterbium and four manganese atoms bound by isocarbonyl
linkages form rings (Figure 3b) containing 4 Mn(CO)5 and
4Yb(THF)2(Et2O)2 units, similar to {(Pyr)4Yb[(µ-CO)2Co-
5
(CO)2]2}∞ . A cross-section of this zigzag puckered sheet
(Figure 4b) shows that the Mn(CO)5 units lie above and
below the plane containing the Yb atoms, as in the compound
cited above. The C-O-Yb angles are 158.8(6) and 159.4(5)°,
noticeably less than 180°, indicating internal constraints in
the structure. Significant disorder was present in the carbon
atoms of THF and in some oxygen atoms of CO. The Yb-O
bond distances to THF, 2.470(4) and 2.473(5) Å, are longer
than those in 1 and 2, corresponding to the large (8-fold)
coordination number of Yb here. The Mn-C distances in 3
are of two types, terminal (average 1.769(8) Å) and bridging
(average 1.823(9) Å), with average C-O distances of
1.172(8) and 1.139(9) Å, respectively. Some disorder is
observed in THF and Et2O ligands in this structure (see
Supporting Information).
Molecular Structure of 4. The molecular structure of 4
is shown in Figure 5. Crystallographic data are given in Table
2, and selected bond distances and bond angles are given in
Table 4. As in compound 3, the asymmetric unit of 4 consists
of half of an Yb atom, two ligands, and one pentacarbon-
ylmanganese anion. The substantial difference is that the two
ligands coordinated to the Yb2+ center are both THF
molecules (in 3, one is a THF molecule and the other one is
Et2O). Symmetry transformations of the unique atoms
generate a one-dimensional polymeric chain (Figure 5).
Linear chains of 4 are composed of four-member diamonds
(Figure 5b) that have alternatively two ytterbium and two
manganese atoms at their vertexes, the former being the
Minor Products of Condensation of 1 with Et2O.
Molecular Structures of (THF)2Mn3(CO)10 (5) and
[(THF)5Yb(µ-CO)Mn3(CO)13][Mn3(CO)14] (6). After com-
pound 4, with some mother liquor, was allowed to sit in a
flask for 3 weeks, ruby-red crystals of 5 formed in the
mixture with the original crystals of 4. This compound was
synthesized and characterized previously28 via the reaction
of Mn2(CO)10 with AlMe3 in a mixture of THF and hexanes,
which led to several products, including 5. The authors could
not reproduce their synthesis: all repeated attempts to isolate
compound 5 only led to formation of Mn2(CO)10. Unfortu-
nately, we could not duplicate the synthesis either. Neverthe-
less, we report this result as confirmation of the existence
of (THF)2Mn3(CO)10 and proof of its relative stability.
Repeated efforts to prepare 5 resulted either in no reaction
or formation of [(THF)5Yb(µ-CO)Mn3(CO)13][Mn3(CO)14],
6 (Figure 6).
The crystallographic data for compound 5, selected bond
distances and angles, and its molecular structure are given
in the Supporting Information. Complex 5 is predicted to be
paramagnetic,29 and it would be interesting to prepare a
sufficiently large quantity of this material to investigate its
magnetic properties.
(28) Kong, G.; Harakas, G. N.; Whittlesey, B. R. J. Am. Chem. Soc. 1995,
117, 3502.
(29) Xu, Z., Lin, Z. Chem.sEur. J. 1998, 4, 28.
10122 Inorganic Chemistry, Vol. 45, No. 25, 2006

Lanthanide-Transition Metal Carbonyl Complexes
Figure 6. Molecular structure of 6 (35% probability ellipsoids shown): (a) the [(THF)5Yb(µ-CO)Mn3(CO)13]+ cation (only oxygen atoms of THF shown)
and (b) the [Mn3(CO)14]- anion.
Ion-paired compound 6 tends to form more predictably
than 5, crystallizing in about 3 to 4 weeks in the flask
containing crystals of 4 with some mother liquor from which
the latter was grown. This process is reproducible but every
time with a different degree of success. We were unable to
determine what conditions favor the formation of 6. The
analogous molecule Mn2Fe(CO)14 has been prepared by UV
photolysis of an equimolar solution of Fe(CO)5 and Mn2-
(CO)10 in n-hexane.30 Dark-red crystals of 6 are always mixed
with 4, and both 4 and 6 are soluble and insoluble in the
same sets of solvents. For these reasons, no elemental
analysis or infrared data were obtained.
carbonyl dimer. For the bridging carbonyl, the Mn-C
distance (1.790(6) Å) is significantly shorter than corre-
sponding distances for the equatorial CO ligands (1.830(7)
Å average). For comparison, average Mn-C distances in
Mn2Fe(CO)14 are 1.855(10) (equatorial) and 1.805(10) Å
(axial). The reasons for such length differences were
thoroughly discussed elsewhere.32 In both free and bound
[Mn3(CO)14] units, equatorial carbonyls of Mn(CO)5 groups
are bent inward, a phenomenon that has been observed for
a number of carbonyl-containing systems.32 In the bound
[Mn3(CO)14] unit, this is slightly more pronounced for one
of the ligands (C(14)-Mn(1)-Mn(2) ) 78.58(15)°) than for
any other (85(2)°, averaged over both bound and free anions).
The Yb-O(OC) distance (2.437(4) Å) is longer then any of
the Yb-O(THF) distances (2.378(4) Å).
In conclusion, a series of new lanthanide-transition metal
compounds was prepared. Solvent-separated ion-paired spe-
cies 1, 1a, 1b, 1c, and 2 were synthesized first, and
compound 1 was then converted into polymeric structures 3
and 4, containing isocarbonyl linkages. The conversion was
achieved by stirring 1 with diethyl ether, which facilitated
condensation of separated cations and anions into a polymer.
Compound 3, formed initially, has a layer sheet structure.
Compound 4, formed after an extended time from the mother
liquor of 3, is a one-dimensional chain. Minor products 5
and 6 were observed and characterized by single-crystal
X-ray diffraction.
Crystallographic data for compound 6 and selected bond
distances and bond angles are presented in the Supporting
Information. Complex 6 is an ionic compound that contains
a rarely observed anion, [Mn3(CO)14]-, which is isoelectronic
30
with Mn2Fe(CO)14 and has similar geometry. It was first
reported by Curtis,31 and its X-ray structure was published
by Bau and collegues.32 Uniquely, there are two such units
in our structure and one of them is connected to the YbII
center through an isocarbonyl linkage, thus forming the
complex cation [(THF)5Yb(µ-CO)Mn3(CO)13]+ (Figure 6a)
(the other [Mn3(CO)14]- anion remains free). In this cation,
ytterbium has distorted octahedral coordination. The isocar-
bonyl bridge belongs to the central manganese atom of the
[Mn3(CO)14] core, and four out of five THF ligands are
disordered. In the free [Mn3(CO)14]- anion (Figure 6b), the
central Mn atom resides on a center of inversion; thus there
is one unique Mn(CO)5 moiety and two carbonyl ligands
attached to the central manganese, the rest of the anion being
symmetry generated. While the free anion possesses crys-
tallographically imposed linear character and is of D4h
symmetry, the anion bound to the Yb atom is slightly bent
(Mn(1)-Mn(2)-Mn(1)′ angle ) 172.62(4)°), and Mn(2) lies
on a mirror plane. In the complex cation, the Mn-Mn
distance (2.8841(7) Å) is shorter than that in Mn2(CO)10
(2.9042(8) Å);33 the length of the same bond in the free anion
(2.9023(7) Å) is closer to the value for the manganese
Experimental Section
General Procedures. All manipulations were carried out on a
standard high-vacuum line or in a drybox under a nitrogen or argon
atmosphere. Diethyl ether, tetrahydrofuran, pyridine, toluene, and
1,2-dimethoxyethane (DME) were dried over sodium/benzophenone
and freshly distilled prior to use. N,N-Dimethylformamide (DMF)
was shaken over type 4 Å Linde molecular sieves for 48 h. The
sieves and Celite were dried under dynamic vacuum for 18 h at
130 °C prior to use. Ytterbium powder (Strem) and metallic mercury
(Bethlehem Apparatus, Inc., quadruple-distilled) were used as
received. Dimanganese decacarbonyl and dirhenium decacarbonyl
(Aldrich) were purified by vacuum sublimation at 100 °C. Elemental
analyses were performed by Galbraith Laboratories, Inc. (Knoxville,
TN). Prolonged pumping on crystalline samples caused loss of
solvent ligands. Therefore, samples of compounds 1 and 2 were
sent to the analytical laboratory packed in dry ice, and analyses
(30) Agron, P. A.; Ellison, R. D.; Levy, H. A. Acta Crystallogr. 1967, 23,
1079.
(31) Curtis, M. D. Inorg. Chem. 1972, 11, 802.
(32) Bau, R.; Kirtley, S. W.; Sorrell, T. N.; Winarko, S. J. Am. Chem.
Soc. 1974, 96, 988.
(33) Bianchi, R.; Gervasio, G.; Marabello, D. Inorg. Chem. 2000, 39, 2360.
Inorganic Chemistry, Vol. 45, No. 25, 2006 10123

Poplaukhin et al.
were calculated taking loss of ligands into account. Infrared spectra
were recorded on a Mattson Polaris Fourier transform spectrometer
with 2 cm-1 resolution. All solution IR spectra were recorded at
the highest concentration that allowed all bands to be nicely resolved
(i.e., the most intense peak reaching nearly zero transmittance). With
the cell path length 0.1 mm, this concentration is estimated to be
(1-3) × 10-3 M.
isotropically. Hydrogen atoms on solvent ligands were calculated
assuming standard geometries.
Preparation of [Yb(L)n][M(CO)5]2, 1, 1a, 1b, 1c, and 2. The
syntheses of these compounds are all similar (except for 2) and
will be given here using [Yb(THF)6][Mn(CO)5]2 as an example.
Note that single crystals and X-ray analyses were obtained for
compounds 1 and 2 only. There are two routes for preparation of
38
1, 1a, 1b, and 1c: (a) via Hg[M(CO)5]2 and (b) via ytterbium
X-ray Structure Determination. From the X-ray studies, it was
found that all of the structures possess disordered THF molecules,
as well as disordered Mn in 1, disordered CO in 1, 2, and 4, and
disordered Et2O in 3. The recognition of disorder was based on
the suggestion in SHELX97 of its possibility for an atom if U1,
the largest of its principal thermal ellipsoid axes, is greater than
0.2 Å2 and if U1 is more than 2.5 times as large as its second largest
such axis. For THF, the splitting was extended over the C atoms,
and the occupancies were estimated using PART 1 and PART 2
options in SHELX97. The temperature factors are large, and only
isotropic temperature factors were used in these disordered regions.
In addition, THF molecules that lie close to the 2-fold axis in 6
were assigned occupancies of 0.5. All but two of these atoms were
refined anisotropically. DFIX restraints were applied to atoms in
the disordered regions: Mn-O (1.81 Å), C-C (1.52 Å), C-O (1.43
Å) for THF and C-O (1.13 Å) for CO, all with esd ) 0.02 Å. The
ordered regions of the structures were not seriously affected by
various changes in the models of the disordered regions, and their
bond distances and angles values appear to be reliable although
they have larger than desirable esd’s. The latter effect seems to be
the result of the very heavy atoms (many electrons) present which
contribute most of the X-ray scattering as well as to the disorder.
amalgam. Compound 2 could only be prepared using route a;
preparation of 2 via route b was attempted several times and failed
repeatedly.
Route a. A 50 mL flask was charged with 296 mg (0.5 mmol)
of Hg[Mn(CO)5]2 and 87 mg (0.5 mmol) of Yb. Approximately 20
mL of THF was condensed into the flask at -78 °C. The mixture
was warmed to room temperature and stirred overnight, during
which time the solution became dark red and Hg appeared. Infrared
spectroscopy was used to monitor the reaction. Filtration of the
reaction mixture through Celite gave a dark-red filtrate. Dark-red
chunklike crystals appeared in 1 day after slow evaporation of the
solvent at room temperature until 3 mL of solution remained. It
was found that to obtain the best X-ray quality crystals, the initially
crystallized material should be left in the mother liquor for about
a week at room temperature. The mother liquor was then removed,
and the crystals were washed with 3 mL of THF and 10 mL of
hexanes. The crystals were dried under vacuum for 5 min, yielding
338 mg of 1 (68% yield based on Hg[Mn(CO)5]2). Anal. Calcd for
YbMn2C26H32O14 (-2 THF): C, 36.7; H, 3.80. Found: C, 36.25;
H, 3.90. For 2, the yield was somewhat lower (340 mg, 54% based
on Hg[Re(CO)5]2). For 1c, Anal. Calcd for YbMn2C30H20O10N4 (-2
pyr): C, 40.9; H, 2.29. Found: C, 39.6; H, 2.68. For 2, Anal. Calcd
for YbRe2C18.8H17.6O12.2 (-3.8 THF): C, 22.94; H, 1.81. Found:
C, 22.56; H, 2.00.
Route b. A 50 mL flask was charged with ytterbium amalgam
prepared from ∼5 mL of Hg, 95 mg (0.55 mmol) of Yb, and 195
mg (0.5 mmol) of Mn2(CO)10. Approximately 20 mL of THF was
condensed into the flask at -78 °C. The mixture was warmed to
room temperature and stirred overnight, during which time the
solution became dark red. Subsequent treatment of the solution led
to a crop of crystals that were the same as those obtained from
route a. Yield of 1: 358 mg (72% based on Mn2(CO)10).
Preparation of {(THF)2(Et2O)2Yb[(µ-(CO)2Mn(CO)3)2]}∞, 3.
In a 50 mL flask, compound 1 was prepared from 118 mg (0.20
mmol) of Hg[Mn(CO)5]2 and 35 mg (0.20 mmol) of Yb. The THF
solvent was removed under vacuum, and ∼30 mL of Et2O was
condensed into the flask at -78 °C. The mixture was warmed to
room temperature and stirred overnight, during which time the
solution became green. Filtration of the reaction mixture through
Celite gave a green filtrate. Emerald-green crystals of 3 appear
immediately when evaporation of the solvent begins. Good X-ray
quality material can be obtained at an evaporation rate of ∼3.5-4
mL/h. Yield: 57 mg (33% based on Hg[Mn(CO)5]2). Dry crystals
of 3 lose coordinated Et2O easily. Anal. Calcd for YbMn2C18H16O12
(-2Et2O): C, 30.6; H, 2.28. Found: C, 30.4; H, 2.69.
Single crystals of compounds 1-6 were grown using the slow
evaporation of solvent technique and kept in their mother liquor
until just before they were mounted on the X-ray diffractometer.
Compound 2 was difficult to crystallize, and our best attempts only
led to crystals of relatively low quality. Single-crystal X-ray
diffraction data were collected using graphite-monochromated Mo
KR radiation (λ ) 0.71073 C) on a Nonius KappaCCD diffraction
system. Single crystals of 1-6 were mounted on the tip of a glass
fiber coated with Fomblin oil (a perfluoropolyether) that provided
protection from the atmospheric oxygen. Crystallographic data were
collected at 200 K for all compounds. Unit cell parameters were
obtained by indexing the peaks in the first 10 frames and were
refined employing the whole data set. All frames were integrated
and corrected for Lorentz and polarization effects using the Denzo-
SMN package (Nonius BV, 1999).34 Absorption corrections were
applied to structures 1, 3, 5, and 6 using the SORTAV program35
provided by MaXus software.36 Absorption corrections for structures
2 and 4 were accounted for by using SCALEPACK. All of the
structures were solved by direct methods and refined using the
SHELXTL-97 (difference electron-density calculation, full matrix
least-squares refinements) structure solution package, and some
other programs.37 For each structure, all the non-hydrogen atoms
were located and refined anisotropically with the exception of the
carbon atoms of the Et2O and THF ligands in 3 that were refined
Preparation of {(THF)4Yb[(µ-CO)2Mn(CO)3)2]}∞, 4. In a 50
mL flask, compound 1 was prepared from 591 mg (1.0 mmol) of
Hg[Mn(CO)5]2 and 173 mg (1.0 mmol) of Yb. The THF solvent
was removed under vacuum, and ∼35 mL of Et2O was condensed
into the flask at -78 °C. The mixture was warmed to room
temperature and stirred overnight, during which time the solution
became green. Filtration of the reaction mixture through Celite gave
a green filtrate. The filtrate was allowed to remain in the flask for
(34) Otwinowski, Z.; Minor, W. In Methods in Enzymology; Carter, C.
W., Jr., Sweet, R. M., Eds.; Academy Press: New York 1997; Vol.
276A, p 307.
(35) Blessing, R. H. J. Appl. Crystallogr. 1997, 30, 421.
(36) Mackay, S.; Gilmore, C. J.; Edwards, C.; Tremayne, M.; Stuart, N.;
Shankland, K. MaXus; University of Glasgow: Glasgow, Scotland;
Nonius BV: Delft, The Netherlands; and MacScience Co., Ltd.:
Yokohama, Japan, 1998.
(37) (a) Sheldrick, G. M. SHELXTL-97; University of Go¨ttingen: Go¨ttingen,
Germany, 1998. (b) WinGX, version 1.70.01. Farrugia, L. G. J. Appl.
Crystallogr. 1999, 32, 837-838.
(38) Hsieh, A. T. T.; Mays, M. J. J. Chem. Soc. A 1971, 2648.
10124 Inorganic Chemistry, Vol. 45, No. 25, 2006

Lanthanide-Transition Metal Carbonyl Complexes
3 days, during which time its color changed from green to yellow.
Dark Yb precipitate formed on the bottom of the flask, and crystals
of 4 began to appear on the flask’s walls. The Et2O solvent was
then evaporated in the course of 4 more days until ∼3 mL of it
remained, producing well-shaped yellow crystals of 4 stuck to the
walls. The remaining solvent was pipetted out, and the crystals were
carefully collected with a spatula. Yield: 238 mg (28% based on
Hg[Mn(CO)5]2). Anal. Calcd for YbMn2C18H16O12 (-2 THF): C,
30.6; H, 2.26. Found: C, 28.9; H, 2.81.
for 7 days in a 50 mL flask, at the end of which period large, needle-
shaped ruby-red crystals of 6 formed. The only way crystals of 6
could be separated from the remaining crystals of 4 was by means
of hand-picking them, since both 4 and 6 are soluble and insoluble
in the same solvents. The amount of the material formed never
exceeded 4 crystals at a time. This and the difficulty of a clean
reproduction of the synthesis prevented us from performing analyses
other than the X-ray diffraction on this compound.
Preparation of (THF)2Mn3(CO)10, 5. A 50 mL flask containing
crystals of 4 and ∼2 mL of the mother liquor was allowed to remain
for 5 days, during which time the material in the flask started to
turn from yellow to red. Investigation under a microscope revealed
that yellow crystals of 4 were mixed with some ruby-red crystals,
that were identified as compound 5. All subsequent attempts to
repeat this preparation led either to the formation of 6, or they did
not yield results. For this reason, no analyses except the X-ray
structure determination were performed on this compound.
Preparation of [(THF)5Yb(µ-CO)Mn3(CO)13][Mn3(CO)14], 6.
Crystals of 4 and ∼2 mL of the mother liquor was allowed to remain
Acknowledgment. This work was supported by the
National Science Fondation through Grant CHE 02-13491.
Supporting Information Available: Detailed X-ray structural
data including a summary of crystallographic parameters, atomic
coordinates, bond distances and angles, anisotropic thermal param-
eters, and H atom coordinates for structures 1-6, and the IR spectra
of compounds 1, 1a, 1b, 1c, 2-4. This material is available free
of charge via the Internet at http://pubs.acs.org.
IC060756K
Inorganic Chemistry, Vol. 45, No. 25, 2006 10125