Heteronuclear bonding between heavier Group 14 elements and transition-metals: Novel halogermylene- and stannylene transition-metal complexes L2(X)MM′L′n [L2=PhNC(Me)CHC(Me)NPh; X=Cl, I; M=Ge, Sn; M′L′n=W(CO)5, Fe(CO)4]

Article abstract of DOI:10.1016/S0022-328X(03)00144-X

Reactions of the stable heteroleptic halodivalent species L² (X)M [L²=PhNC(Me)CHC(Me)NPh; M=Ge, X=Cl (1); X=I (2); M=Sn, X=Cl (5)] with the intermediate metal complexes W(CO)₅ THF and Fe(CO) 4 have provided the new halogermylene- or stannylenetungsten- and iron-complexes L²(X)MM′L′n [M′L′ n =W(CO ₅, M=Ge, X=Cl (3), X=I (4); M′L′ n =Fe(CO ₄, X=Cl, M=Ge (6), M=Sn (7)] respectively; complexes 3, 4 and 6, 7 have been characterized via X-ray crystallography and a detailed discussion of their structures is presented. All the MM′ bonds are very short but calculations are consistent with the L²MX ligands being good σ-donors and very poor π-acceptors in complexes 3, 4 and 6, 7. Selective metathesis reaction between 3 and MeLi resulted in the formation of the stable monomeric complex L²(Me)GeW(CO)₅ (8).

Full text of DOI:10.1016/S0022-328X(03)00144-X

Journal of Organometallic Chemistry 672 (2003) 77Á85
/
www.elsevier.com/locate/jorganchem
Heteronuclear bonding between heavier Group 14 elements and
transition-metals: novel halogermylene- and stannylene transition-
2
2
?
metal complexes L (X)MM?Ln [L ꢀ
/
PhNC(Me)CHC(Me)NPh; Xꢀ
/
?
Cl, I; Mꢀ
/
Ge, Sn; M?Lnꢀ
/
W(CO)5, Fe(CO)4]
Isabelle Saur a, Ghassoub Rima a, Karinne Miqueu b, Heinz Gornitzka a,
Jacques Barrau a,*
a He´te´rochimie Fondamentale et Applique´e, UMR 5069, Universite´ Paul Sabatier, 118, route de Narbonne, F-31062 Toulouse Cedex 4, France
b Laboratoire de Physico-Chimie Mole´culaire, UMR 5624, Universite´ de Pau et des Pays de l’Adour Av. de l’Universite´, BP 1155, F-64013 Pau Cedex,
France
Received 20 January 2003; received in revised form 20 January 2003; accepted 26 February 2003
Abstract
Reactions of the stable heteroleptic halodivalent species L2(X)M [L2ꢀ
MꢀSn, XꢀCl (5)] with the intermediate metal complexes W(CO)5 THF and Fe(CO)4 have provided the new halogermylene- or
stannylenetungsten- and iron-complexes L (X)MM?Ln [M?Lnꢀ
MꢀGe (6), MꢀSn (7)] respectively; complexes 3, 4 and 6, 7 have been characterized via X-ray crystallography and a detailed
/
PhNC(Me)CHC(Me)NPh; Mꢀ
/
Ge, Xꢀ
/
Cl (1); Xꢀ
/
I (2);
/
/
2
?
?
?
/
W(CO)5, Mꢀ
/
Ge, Xꢀ
/
Cl (3), Xꢀ
/
I (4); M?Lnꢀ
/
Fe(CO)4, Xꢀ
/
Cl,
/
/
discussion of their structures is presented. All the MM? bonds are very short but calculations are consistent with the L2MX ligands
being good s-donors and very poor p-acceptors in complexes 3, 4 and 6, 7. Selective metathesis reaction between 3 and MeLi
resulted in the formation of the stable monomeric complex L2(Me)GeW(CO)5 (8).
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Transition-metal complexes of M14 divalent species; Germanium; Tin; Tungsten; Iron
1. Introduction
complex [3]. Among the attractive features of such
?
halogen-bound organometallic compounds L(X)MM?Ln
The transition-metal complexes, with formal multiple
bonding between the metal M? and the heavier Group 14
element M, have attracted much interest in the past
decade because these metallic analogues of carbenic
transition-metal complexes are involved as intermedi-
ates in the transition metal-catalyzed reactions of
[Xꢀ
/
halogen], they appear to be precursors to various
?
alkylated L(R)GeM?Ln complexes. They thus offer the
possibility to modulate the effect that the R moiety has
on the nature of the MM? bond and on the lability of the
complexes. These properties can be exploited in catalytic
systems. We have previously studied various transition-
metal complexes of stable homoleptic Schiff base and
phenoxy divalent Group 14 element species,
L2MM?(CO)5, L2MM?(CO)4 and (L2M)2M?(CO)4
formation and/or cleavage of Mꢀ
/
C and Mꢀ
/
M bonds
?
[1]. Various R2MM?Ln structures with three-, four- or
five-coordinate M atoms have been isolated to date [2];
but it is noteworthy that the germylenetungsten complex
[L2ꢀ
(ꢁ)-N,N?-bis(3,5-di-tert -butylsalicylidene)-1,2-cyclo-
hexanediamine, and N-methyl-2,2?-iminobis(8-hyhroxy-
quinoline); MꢀGe, Sn, Pb; M?ꢀCr, W, Fe. Lꢀ2,4,6-
tris[(dimethylamino)methyl]phenyl-; MꢀGe, Sn, Pb;
M?ꢀCr, W, Fe, Pt] [2o,4]. To learn more about the
nature of metalÁgermylene and Ástannylene bonding
interactions we have used the stable heteroleptic divalent
/
2,2?-N,N?-bis(salicylidene)ethylenediamine, (R,R)-
/
(h2ꢀ
ple of an heteroleptic halogermylene transition-metal
/Me5C5)(Cl)GeW(CO)5 is the unique known exam-
/
/
/
/
/
* Corresponding author. Tel.:
558204.
E-mail address: barrau@chimie.ups-tlse.fr (J. Barrau).
ꢂ
/
33-561-556172; fax:
ꢂ/33-561-
/
/
0022-328X/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00144-X

78
I. Saur et al. / Journal of Organometallic Chemistry 672 (2003) 77Á85
/
1
germanium(II) and tin(II) species supported by chelat-
ized by H- and 13C-NMR, IR and mass spectroscopy.
These complexes show high thermal stability, as indi-
cated by the high melting point and the presence of the
molecular ion peak in the EI 70 eV mass spectrum of 3
(the 100% intensity peak can be attributed to L2Geꢂ). It
is noteworthy that the mass spectroscopy analysis of 4,
which bears the weakly coordinating anion Iꢁ, does not
show detectable molecular ion peak in this case; the
prominent peak being [L2Ge]ꢂ. Mass spectra of both 3
and 4 likewise display the fragmentation patterns of
these structures (successive losses of the halides and the
ing b-diiminate ligand, L2(X)M [L2ꢀ
/
PhNC-
Ge (1), Sn (5); XꢀI,
Ge (2)], as precursors of the first*
except (h2-
Me5C5)(Cl)GeW(CO)5*
halide complexes L2(X)M-
W(CO)5; MꢀGe; XꢀCl (3), XꢀI (4).
Fe(CO)4; XꢀCl; MꢀGe (6), Sn (7)]. We
(Me)CHC(Me)NPh, Xꢀ
/
Cl, Mꢀ
/
/
Mꢀ
/
/
/
?
?
M?Ln [M?Lnꢀ
/
/
/
/
?
M?Lnꢀ
/
/
/
report here the syntheses, crystal structures and some
chemical properties of these new bimetallic compounds.
The nature of the MꢀM? bonds in these species is
/
discussed in terms of s-donor and p-acceptor properties
of the L2(X)M ligands toward the M? atoms. Prelimin-
ary results of this work have been communicated earlier
[5]. It was reported that L2(Cl)M three-coordinate
divalent species have also been used recently as pre-
cursors of the corresponding ‘halogermanechalco-gen-
carbonyl groups). For 3 and 4 the H- and 13C-NMR
1
spectra show the equivalences of the methyl, and phenyl
groups of the ligand as in the cases of the parent
germylenes 1 and 2 [5a]. These results are indicative of a
1
mirror symmetry for the ligand in solution. The H and
ones’ L2(Cl)GeY (Yꢀ
S, Se), the first examples of
/
13C chemical shifts of the methine and methyl groups for
3 appear significantly downfield compared to the
corresponding resonances due to the equivalent protons
of the divalent species 1 (this feature is less obvious for 4
compared to 2) (Table 1); similarly the methine 1H- and
13C-NMR resonances in 4 are strongly shifted downfield
in comparison to 3. This deshielding is consistent with
an increased positive charge at the germanium center (or
on the L2Ge ligand) (Table 1). Two 13C-NMR reso-
nances for the CO groups, and three bands in the IR
spectra, which can be attributed to the infrared-active
formally multiply-bonded heavier Group 14 elements
bearing a halogen [5a,6].
2. Results and discussion
2.1. Complexes L2(X)GeW(CO)5 (Xꢀ
The reaction of THF solution of the L2(X)Ge
/
Cl (3), I (4))
germylenes 1 and 2 [XꢀCl (1); XꢀI (2)] with the
photochemically produced W(CO)5×THF intermediate
gave the expected dinuclear germylenetungsten com-
plexes L2(X)GeW(CO)5 [Xꢀ
Cl (3); XꢀI (4)] in high
yields (Scheme 1).
/
/
carbonyl stretching frequencies (A(11)ꢂ
/
A(12)ꢂ
E), are
/
/
characteristic of C4v local symmetries around the
tungsten in 3 and 4 (Table 1). Since the unique COax
to the germanium is involved in the A(11) mode, the
position of this band [1984 (3), 1984 (4) cmꢁ1] seems
indicative of a p-acceptor ability of the L2(X)Ge groups
trans to the axial carbonyl [7]. The structures of 3 and 4
/
/
Complexes 3 and 4 are yellow solids, soluble in polar
or aromatic solvents and insoluble in pentane; they are
air- and moisture-sensitive. They were fully character-
Scheme 1. Synthesis of complexes (3Á
/
4) and (6Á7).
/

I. Saur et al. / Journal of Organometallic Chemistry 672 (2003) 77Á
/
85
79
Table 1
1H- and 13C-{1H}-NMR(CDCl3) and IR data for compounds 1, 2, 3, 4
a
1
2 a
3
4
1H-NMR (d,
ppm)
CH
5.40
1.99
5.64
2.05
5.56
2.02
5.82
2.01
CH3
13C-NMR (d,
ppm)
CH
101.50 103.28 101.58
23.52 23.34 24.60
103.04
24.55
CH3
CO
Á/
Á/
195.88, 199.22 196.58, 199.32
IR
nCO (cmꢁ1
Á
Á/
/
Á
Á/
/
)
2072, 1984,
1943
2071, 1984,
1945
Fig. 2. Crystal structure of 4 (ellipsoids are drawn 50% probability
˚
level). Selected bond lengths (A) and bond angles (8): Geꢀ
GeꢀN1 1.915(5), GeꢀN2 1.916(5), GeꢀW 2.571(7), WꢀC4 1.978(8),
WꢀC1 2.047(8), WꢀC2 2.027(6), WꢀC3 2.040(8), WꢀC5 2.028(7),
N1ꢀGeꢀN2 93.9(2), N1ꢀGeꢀI 97.13(15), N2ꢀGeꢀI 95.84(14), N1ꢀ
GeꢀW 125.94(15), N2ꢀGeꢀW 125.41(17), IꢀGeꢀW 111.75(2), Geꢀ
WꢀC4 174.2(3), GeꢀWꢀC1 96.11(19), GeꢀWꢀC2 85.96(17), GeꢀWꢀ
C3 88.5(2), GeꢀWꢀC5 93.10(18).
/
I 2.653(1),
/
/
/
/
a
Ref. [5].
/
/
/
/
/
/
/
/
/
/
/
were unambiguously established by single-crystal X-ray
diffraction. Suitable crystals of 3 and 4 were obtained in
chloroform at ꢁ78 8C. The molecular structures of 3
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
and 4 are depicted in Figs. 1 and 2. Crystallographic
data are given in Table 2. The molecular structures of 3
and 4 confirm the monomeric nature of these complexes
and the four-coordinated environment of the germa-
nium centers; both 3 and 4 have severely distorted
tetrahedral geometries around the germanium, with the
sums of the angles at the metal center deviating from the
and 2 and tetracoordinate for 3 and 4). The Geꢀ
GeꢀX bonds in complexes 3 and 4 [GeꢀN: 1.929(3),
1.923(3) A (3); 1.916(5), 1.915(5) A (4). GeꢀX: 2.258(1)
A (3); 2.653(1) A (4)] are slightly shorter than those in
divalent species 1 and 2, respectively [GeꢀN: 1.955(2),
1.965(1) A (1); 1.959(4), 1.971(4) A (2). GeꢀX: 2.340(6)
A (1); 2.778(6) A (2)]. These differences may be
ascribable to the diminished electronic densities around
the germanium in 3 and 4 compared to 1 and 2.
/
N and
/
/
˚
˚
/
˚
˚
/
˚
˚
/
sp3 tetrahedral value [the sums of the N(1)ꢀ
N(1)ꢀGeꢀX, XꢀGeꢀW, N(2)ꢀGeꢀW bonds angles are
427.68 (3) and 428.28 (4)]. The N(1)ꢀGeꢀN(2) angles
/
Geꢀ
/
N(2),
˚
˚
/
/
/
/
/
/
/
/
Moreover, the Geꢀ
/
X bonds for 3 and 4 are longer by
˚
0.12 A than those for more basic corresponding
observed in the four-coordinate complexes 3 and 4
[93.98 (3), 93.98 (4)] are wider than those observed in the
three-coordinate germylenes L2(X)Ge [90.38 (1), 91.88
(2)] [5b], probably due to the change of coordination
number of the germanium centers (tricoordinate for 1
Â
/
halogenated germanium(IV) compounds [8]. All these
data are consistent with geometries around the germa-
nium centers in 3 and 4 that are in fact between distorted
trigonal pyramids and tetrahedrons (see side views, Fig.
3).
In both complexes 3 and 4, the geometry around the
tungsten is nearly octahedral (Figs. 1 and 2). The Geꢀ
/
W
bond lengths [2.567(5) A (3), 2.571(7) A (4)] are nearly
˚
˚
identical to those observed for (h2-Me5C5)(Cl)-
˚
GeW(CO)5 [2.571(1) A] [3] and for various halogerma-
nium(IV) complexes (h5-C5R5)M(CO)3GeCl3 (Rꢀ
H,
Me; MꢀMo, W) [8c,8d,8e]. They are among the
shortest reported for compounds of R2GeW(CO)5 type
[2i,2m,2q,2r,9]; and even shorter than the GeꢁW bond
/
/
/
1
2
˚
length of 2.593(1) A determined for Ar Ar Geꢀ
W(CO)5 [Ar1ꢀ
2,4,6-tris[bis(trimethylsilyl)methyl]phe-
nyl, Ar2ꢀ
2,4,6-triisopropylphenyl] in which the germa-
nium atom is three-coordinated [2i]. The range for an
/
/
/
Fig. 1. Crystal structure of 3 (ellipsoids are drawn 50% probability
˚
level). Selected bond lengths (A) and bond angles (8): Geꢀ
/
Cl 2.258(1),
˚
2.67 A
Geꢀ
WꢀC18 2.033(4), Wꢀ
N1ꢀGeꢀN2 93.90(13), N1ꢀ
N1ꢀGeꢀW 124.97(9), N2ꢀGeꢀ
GeꢀWꢀC22 174.83(14), Geꢀ
89.50(12), GeꢀWꢀC19 95.49(12), Geꢀ
/
N1 1.929(3), Geꢀ
C21 2.035(5), Wꢀ
GeꢀCl 96.64(9), N2ꢀ
W 124.73(10), Clꢀ
WꢀC18 92.11(11), Geꢀ
WꢀC20 85.79(11).
/
N2 1.923(3), Geꢀ
C19 2.040(5), Wꢀ
Geꢀ
Geꢀ
/
W 2.567(5), Wꢀ
/
C22 1.995(5),
interatomic Geꢀ
/
W
single bond is 2.59Á
/
/
/
/
/
C20 2.043(4),
[2m,2q,10]. It is noteworthy that in the two complexes
˚ ˚
Cax bonds [1.995(5) A (3); 1.978(8) A (4)] are
/
/
/
/
/
/Cl 98.08(10),
the Wꢀ
/
/
/
/
/
/
/W 112.34(3),
˚
2.038 A (3);
slightly shorter than the Wꢀ
/
Ceq bonds [Â
/
/
/
/
/
/
WꢀC21
/
˚
/
/
/
/
Â
/
2.035 A (4)] and are the largest among the Wꢀ
/Cax

80
I. Saur et al. / Journal of Organometallic Chemistry 672 (2003) 77Á85
/
Table 2
Crystallographic Data for 3, 4, 6, 7
Compounds
3
4
6
7
Empirical formula
Formula weight
Crystal system
C
681.27
22H17ClGeN2O5W
C22H17IGeN2O5W
772.72
C21H17ClFeGeN2O4
525.26
C21H17ClFeN2O4Sn
571.36
orthorhombic
P212121
orthorhombic
P212121
orthorhombic
P212121
orthorhombic
Pnma
Space group
Unit cell dimensions
˚
a, (A)
6.684(1)
17.959(2)
19.508(2)
2341.6(4)
4
6.860(1)
18.405(2)
19.620(2)
2477.1(5)
4
12.232(10)
13.230(6)
13.714(7)
2219(2)
4
13.420(7)
14.170(9)
12.001(7)
2282(2)
4
˚
b, (A)
˚
c, (A)
3
˚
V, (A )
Z
Dcalc, (Mg mꢁ3
)
1.932
2.072
1.572
1.663
Reflections collected
Independent reflections
Parameters
19708
5796
291
20974
6402
291
12888
4474
273
12710
2458
234
R1 [I ꢀ
wR2 (all data)
Largest difference peak and hole (e. A
/
2s(I)]
0.0236
0.0502
0.0370
0.0835
0.0216
0.0466
0.0239
0.0560
ꢁ3
˚
)
1.330 and ꢁ
/0.968
2.071 and ꢁ
/1.859
0.390 and ꢁ
/0.275
0.420 and ꢁ0.350
/
Table 3
Geometrical parameters (bond lengths in angstroms and bond angles
in degrees) and Wiberg Bond Indices in parenthesis
1?
2?
GeCl
2.343 (0.640)
1.994 (0.474)
1.994 (0.474)
1.344 (1.404)
1.422 (1.364)
1.422 (1.364)
1.344 (1.405)
2.267 (0.688)
1.931 (0.481)
1.933 (0.480)
1.347 (1.379)
1.420 (1.371)
1.421 (1.370)
1.347 (1.380)
2.607 (0.455)
90.39
GeN1
GeN2
N1C7
Fig. 3. Side view of 3, 4, and 6, 7. CO groups are omitted for clarity.
C7C8
C9C8
N2C9
bonds yet observed in germylenetungsten complexes
GeW
Á/
[2i,2m,2q,2r,9]. All these data seem indicative of Geꢀ
/
N1GeN2
N1GeCl
N2GeCl
WGeCl
86.84
95.90
95.84
W bonds with unsaturated character (hyperconjugation
[8c,8d,8e]). Accordingly the L2(X)Ge moiety could be
seen, toward the W(CO)5 moiety, as strong s-donors
with weak p-acceptor capacities; nevertheless the p
98.38
98.30
Á/
122.24
contributions in these germaniumÁ
seem less lower than those in the few known base-
stabilized germyleneÁpentacarbonyltungsten complexes
[2m,2q,2r,9].
In order to estimate the overall bonding situation of
the L2GeX ligand in these germanium(II)Átungsten
complexes a DFT(B3LYP) theoretical study was carried
out for the model (without phenyl substituents) mole-
cules 1? and 2?. The calculated geometrical parameters of
1? and 2? (Table 3) are in good qualitative agreement
/
tungsten compounds
with the experimental results. For 1?, the calculated
hybrid orbitals (NBO calculation) of the Ge atom for
/
the Geꢀ
and 93.48%, respectively); the lone pair presents a strong
s character (83.16%). On the contrary, for 2? the Geꢀ
and Geꢀ
Cl bonds correspond to a sp2.6 hybridized
germanium atom. Consequently, a shortening of the
N bonds as well as an increase of the
/
N and Geꢀ/Cl bonds are p in character (92.86
/N
/
/
Geꢀ
/
Cl and Geꢀ
/
N(1)GeN(2) and N(1,2)GeCl bond angles are predicted
going from the free ligand L2Ge 1? to the L2Ge fragment

I. Saur et al. / Journal of Organometallic Chemistry 672 (2003) 77Á
/
85
81
Table 4
Total natural charge (NBO calculation)
Table 5
1H- and 13C-{1H}-NMR(CDCl3) and IR data for compounds 5, 6, 7
a
1?
2?
5
6
7
Ge
N1
N2
Cl
1.045
0.940
0.939
0.592
0.387
0.402
0.387
1.392
0.947
0.946
0.498
0.396
0.393
0.396
1.228
1H-NMR (d, ppm)
CH
CH3
ꢁ
/
ꢁ
/
5.15
1.96
5.50
1.97
5.31
2.03
ꢁ
/
ꢁ
/
ꢁ/
ꢁ/
13C-NMR (d, ppm)
C7
C8
C9
W
CH
CH3
CO
100.74
23.96
101.18
24.66
213.14
100.38
24.56
212.40
ꢁ/
ꢁ/
Á/
/
ꢁ/
IR
nCO (cmꢁ1
)
Á/
Á/
2043, 1969,
1947, 1923
2044, 1969,
1950, 1928
in 2?. The germanium pair of the Geꢀ
/W bond presents a
a
Ref. [5].
strong p character (82.66%). This observation could
W bond in 2?. Moreover, taking
explain the short Geꢀ
/
ꢃ
atom in 7 is basically four-coordinate in solution. The
1
into account the energetic positions of the pCN (ꢁ
/
1.46
deshielding also affects the H- and 13C-NMR chemical
ꢁ
ꢃ
ꢃ
eV), sGeN (0.13 eV) and sGeCl (0.27 eV) orbitals of the
L2GeCl fragment and of the d orbital (p symmetry) in
shifts of the signals of complex 7, compared to those of
the free divalent species 5 (Table 5). Though this is the
expected result for the higher coordination number of
Sn in 7, this feature is less obvious for 6. The 1H and 13
W(CO)5 (ꢁ
back-donation dM0
/6.82 eV), it appears that only a very weak
/
ligand could occur. This bonding
situation is witnessed in the Wiberg bond indices (Table
3). Considering the total atomic natural charges (Table
4) for 1? and 2?, it appears that (i) the C8 atom is less
negative in 2? than in 1?, which is in agreement with the
deshielding observed in 13C- and 1H-NMR, (ii) the
chlorine atom is slightly less negative in the complex 2?
than in the free ligand 1?, (iii) the germanium atom is
strongly positive in 2? versus in 1?, and (iv) the tungsten
presents a more important charge in 2? (ꢁ
the free fragment W(CO)5 (ꢁ0.690). These charges are
coherent with a weak back-donation dM0ligand.
In conclusion, these trends can be rationalized assum-
ing a rehybridization of the germanium atom going
from the free ligand L2GeCl (1?) to the complex 2?, the
C
chemical shifts of 6 are in the range of those of 3, but are
slightly shifted to high field indicating a smaller
electron-withdrawing ability for Fe(CO)4 than for
W(CO)5 (Tables 1 and 5). The IR spectra of both
complexes 6 and 7 exhibit four carbonyl bands indica-
tive of a C3v local symmetry at the iron with the ligand
L2(Cl)M in the axial site (Table 5). The structures of 6
and 7 were unambiguously established by single-crystal
X-ray analyses and are shown in Figs. 4 and 5,
respectively. Crystallographic data and processing para-
meters are given in Table 2.
/
1.228) than in
/
/
Geꢀ
donorÁ
back-donation (dM0
seems weak.
/
W bonding being achieved essentially by a strong s
/
acceptor interaction. A tungsten to germanium p
ꢃ
s
ꢃ
GeN) is possible but
/
GeCl, dM0
/
s
2.2. Complexes L2(Cl)MFe(CO)4 (Mꢀ
(7))
/
Ge (6), Sn
The germylene- and stannylene- iron complexes
L2(Cl)MFe(CO)4 [Mꢀ
Ge (6), Sn (7)] were synthesized
by reaction of diiron nonacarbonyl with the correspond-
ing divalent species L2(Cl)M [Mꢀ
Ge (1), Sn (5)] in
/
/
toluene at room temperature (Scheme 1). Complexes 6
and 7 were obtained as yellow solids, in high yields, after
precipitation in pentane. As for 3 and 4, these air- and
moisture-sensitive complexes are soluble in aromatic
Fig. 4. Crystal structure of 6 (ellipsoids are drawn 50% probability
˚
level). Selected bond lengths (A) and bond angles (8): Geꢀ
/
Cl 2.245(13),
C19 1.790(3),
C21 1.785(3), N1ꢀGeꢀN2
GeꢀCl 98.54(6), N1ꢀGeꢀFe
GeꢀFe 119.17(5), GeꢀFeꢀ
C18 91.50(8), GeꢀFeꢀC20 88.86(8), GeꢀFeꢀ
1
and polar solvents. Their H, 13C-NMR, IR and mass
Geꢀ
FeꢀC18 1.790(3), Feꢀ
94.59(8), N1ꢀGeꢀCl 98.31(7), N2ꢀ
119.95(6), N2ꢀGeꢀFe 120.94(6), Clꢀ
175.40(10), GeꢀFeꢀ
84.28(8).
/
N1 1.911(2), Geꢀ
/
N2 1.912(2), Geꢀ
/
Fe 2.298(2), Feꢀ
/
/
/
C20 1.795(3), Feꢀ
/
/
/
spectra are consistent with their formula (Table 5).
/
/
/
/
/
/
The 119Sn NMR signal of 7 at dꢀ
/
80.1 ppm, is shifted
to low field in comparison to the signal of the parent
stannylene 5 [5a] [dꢀ 280 ppm], indicating that the tin
/
/
/
/
/
/
C19
/
/
/
/
/
/
C21
/
ꢁ
/

82
I. Saur et al. / Journal of Organometallic Chemistry 672 (2003) 77Á85
/
˚
˚
metal [1.790(3) A (6), 1.801(5) A (7)] and the Feꢀ
/
Ceq
1.792 A (7)] bonds are almost
Fe distances shorter than those
˚
˚
[Â
/
1.790 A (6), Â
identical. The only Mꢀ
observed in 6 and 7 were determined in the iron
complexes of the bis(aryloxy)Group14 metal(II) species
/
/
(ArO)2MFe(CO)4
[ArOꢀ
/
2,6-tBu2-4-Meꢀ
/
C6H2ꢀ
/
O;
˚
˚
Ge (2.240(2) A), Sn (2.408(1) A)] in which the
Mꢀ
/
(ArO)2M ligands are in equatorial positions due to the
good p-acceptor character of these (ArO)2M ligands
[12b]. Three arguments support the view that the
L2(Cl)M ligands are strong s-donors probably in weak
hyperconjugation with the carbonyl iron fragment: (i)
the Mꢀ
/
Fe bonds in 6 and 7 are shorter than those found
in most complexes containing a tetracoordinated metal
Fig. 5. Crystal structure of 7 (ellipsoids are drawn 50% probability
14 atom [2k,2p,4a,12a,12c,12d,13a,13b,13c], (ii) the M?ꢀ
/
˚
level). Selected bond lengths (A) and bond angles (8): Snꢀ
/
Cl 2.394(1),
C14 1.801(5),
C13 1.800(5), N1ꢀSnꢀN1A
SnꢀCl 97.02(6), N1ꢀSnꢀFe
SnꢀFe 122.10(4), SnꢀFeꢀ
FeꢀC11 85.3(5), SnꢀFeꢀ
C distances are very similar, (iii) the L2(Cl)MFe(CO)4
complexes have trigonal bipyramidal trans configura-
tions at the iron. It is noteworthy that 6 and 7 are the
first group 8 transition-metal complexes of heavier
Group 14 element divalent species bearing a halogen.
Snꢀ
Feꢀ
89.35(13), N1ꢀ
121.90(6), N1Aꢀ
167.7(2), SnꢀFeꢀ
85.94(14).
/
N1 2.091(2), Snꢀ
C10 1.649(14), Feꢀ
SnꢀCl 97.02(6), N1Aꢀ
SnꢀFe 121.90(6), Clꢀ
C10 94.9(5), Snꢀ
/
N1A 2.091(2), Snꢀ
/
Fe 2.440(1), Feꢀ
/
/
/
C11 1.926(13), Feꢀ
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
C14
/
/
/
/
/
/
C13
2.3. Chemical reactivity
These two complexes have similar structural features.
The backbone of the L2 ligand is essentially planar; as
for 3 and 4, the metal 14 atom center adopts a four-
coordinated geometry and resides in an environment
intermediate between a distorted tetrahedron and a
trigonal pyramid (see side view, Fig. 3), while the local
geometry around the iron center is slightly distorted
trigonal bipyramidal. In the two complexes the L2(X)M
moiety occupies an axial position in the trigonal
bipyramid. This indicates that the divalent species
L2(Cl)M are better s-donors than p-acceptors toward
iron in accord with theoretical studies showing that the
axial or equatorial sites preference of a neutral ligand in
trigonal bipyramidal d8 metal(0) carbonyl complexes
can depend on the s-donor and p-acceptor characters of
this ligand, the eq-preference being attributed to ligands
having good p-acceptor character [11,12b]. As expected
due to the difference of the atomic radii of Ge and Sn,
These heteroleptic divalent transition-metal com-
2
?
plexes L (X)MM?Ln present a large potential for
organometallic syntheses since six different reaction
centers can be distinguished. But the widespread interest
in the chemistry of these compounds is essentially due to
the presence of a halogen on the M atom offering
suitable approaches to numerous unusual new com-
plexes. The reactivity of 3 was preliminary studied with
MeLi. The reaction of 3 with MeLi in toluene at ꢁ78 8C
/
is selective and almost quantitative, leading to the
complex L2(Me)GeW(CO)5 8 that has been character-
1
ized by H- and 13C-NMR, IR and mass spectrum. The
thermal stability of this complex is revealed by the
presence of a prominent peak corresponding to the
molecular ion in the EI mass spectrum. In the IR
spectra, the absorption bonds attributed to the carbonyl
frequencies are at lower wavenumbers for complex 8 [8:
2060, 1934, 1920 cmꢁ1] than for complex 3 [3: 2072,
1984, 1943 cmꢁ1], probably due to the difference of the
electronic effects of the chlorine and methyl substitu-
ents.
the bond angle N(1)ꢀ
the corresponding angle N(1)ꢀ
the bond lengths NꢀGe [1.911(2), 1.912(2) A] and Geꢀ
Cl [2.245(1) A] in 6 are slightly shorter than the
/
Geꢀ
/
N(2) [94.68] in 6 is larger than
/
SnꢀN(2) [89.48] in 7, and
/
˚
/
/
˚
˚
corresponding Nꢀ
/
Sn [2.091(2), 2.091(2) A] and Snꢀ
/Cl
˚
[2.394(1) A] bond distances in 7. Further, due to the
change of the metal 14 atom environments (tetracoordi-
3. Conclusion
nate in 6, 7 and tricoordinate in 1, 5), these Mꢀ
MꢀCl bond distances are shorter in 6, 7 (Figs. 4 and 5)
than the corresponding bond lengths in 1 and 5 [Geꢀ
/
N and
/
Four members of a new class of complexes, the
halogermylene- and stannylene- transition-metal com-
/N:
2
˚
˚
?
1.955(2), 1.965(1) A; Geꢀ
/
Cl: 2.340(6) A (1). Snꢀ
/N:
plexes L (X)MM?Ln, have been described. The MM?
˚
˚
Cl: 2.500(3) A (5)] [5a]. The
2.170(9), 2.174(9) A; Snꢀ
/
bond distances in these complexes are among the
shortest ever observed. Calculations indicate that the
L2(X)M ligands are strong s-donors that possess low p-
acceptor properties (hyperconjugation) toward the
M?Ln fragment. Thus if these compounds are described
˚
MꢀFe bond distances [Geꢀ
/
/
Fe: 2.298(2) A (6); Snꢀ
/Fe:
˚
2.440(1) A (7)] are, among the shortest known for any
germylene- [2p,12] and stannylene- [2k,4a,12b,13] iron
Cax to the
complexes respectively. Additionally the Feꢀ
/

I. Saur et al. / Journal of Organometallic Chemistry 672 (2003) 77Á
/
85
83
4.2. L2(Cl)GeW(CO)5 (3)
A tetrahydrofuran solution (60 ml) of W(CO)6 (440
mg, 1.25 mmol) was irradiated for 2 h. CO was
eliminated by bubbling of argon in the reaction mixture
for 15 min, then L2GeCl (450 mg, 1.25 mmol) in
tetrahydrofuran (30 ml) was slowly added at room
temperature. The mixture was stirred for 2 h. The
volatile materials were removed under reduced pressure
to obtain 3 as a yellow solid (83% yield, 710 mg).
Scheme 2. Resonance structures of complexes (3Á
/
4) and (6Á7).
/
in terms of resonance structures between forms contain-
ing Group 14 element-transition metal double bonds
and ylid forms, (as shown in Scheme 2, considering that
the parent compounds 1, 2, and 5 are well described as
Recrystallization from chloroform at ꢁ
yellow crystals of 3: mp 190Á205 8C (dec.). IR
(CHCl3) nꢀ
2072, 1984, 1943 cmꢁ1 (CO). 1H-NMR
(80 MHz, CDCl3): dꢀ2.02 (s, 6H, CH3), 5.56 (s, 1H,
CH), 7.15Á
7.56 (m, 10H, C6H5). 13C-NMR (62.90 MHz,
CDCl3): dꢀ24.60 (s, CH3), 101.58 (s, CH), 128.04 (s,
m-aryl-C), 128.47 (s, p-aryl-C), 130.04 (s, o-aryl-C),
142.43 (s, CꢀN), 167.38 (s, Cipso), 195.88 (s, CO), 199.22
(s, CO). MS: (EI) m/zꢀ
682 [M]ꢂ, 654 [MꢀCO]ꢂ.
/
30 8C gave
L2Mꢂ
the major resonance contributors to the actual struc-
tures of the M14ꢀM? bonds.
/
. . ./
Xꢁ species [5b]), the ylid forms(II) are by far
/
/
/
/
These complexes, by virtue of their polar metal 14-
transition metal and their metal 14-halogen bonds,
appear as useful precursors with high potential in
organometallic chemistry. They offer diverse uses to
develop, via replacement of the chlorine by a more labile
ligand, abstraction of the halogen to afford cationic
metal(II) complexes, and selective substitution of the
halogen for preparation of complexes containing alkyl
groups.
/
/
/
/
/
[D1]Anal. Calc. for C22H17N2O5ClGeW, (681.27): C,
38.70; H, 2.49; N, 4.10. Found: C, 38.75; H, 2.17; N,
4.25%.
4.3. L2(I)GeW(CO)5 (4)
Using the same operating conditions as in the
preceding preparation, 4 was obtained from L2GeI
(370 mg, 0.85 mmol) and W(CO)5 THF (360 mg, 0.85
4. Experimental
4.1. General procedures and materials
mmol). Yield: 86%, 550 mg. 4: mp 178Á180 8C. IR
/
1
(THF) nꢀ
MHz, CDCl3): dꢀ
7.18Á
7.25 (m, 10H, C6H5). 13C-NMR (62.90 MHz,
CDCl3): dꢀ24.55 (s, CH3), 103.04 (s, CH), 126.42 (s,
m-aryl-C), 129.67 (s, p-aryl-C), 130.02 (s, o-aryl-C),
142.40 (s, CꢀN), 168.76 (s, Cipso), 196.58 (s, CO), 199.32
(s, CO). MS: (EI) m/zꢀ645 [Mꢀ Iꢀ
I]ꢂ, 617 [Mꢀ CO]ꢂ.
/
2071, 1984, 1945 cmꢁ1(CO). H-NMR (80
2.01 (s, 6H, CH3), 5.82 (s, 1H, CH),
All manipulations were carried out under an argon
atmosphere with the use of standard Schlenk and high
vacuum line techniques. Solvents were distilled from
conventional drying agents and degassed twice prior to
/
/
/
use [14]. L2(X)M [Mꢀ
XꢀCl (5)] were prepared according to the previously
/
Ge, Xꢀ
/
Cl (1), I (2); Mꢀ
/Sn,
/
/
/
/
/
/
1
reported method [5a]. H-NMR spectra were recorded
on a Bruker AC 80 spectrometer operating at 80 MHz
(chemical shifts are given in ppm (d) relative to Me4Si),
13C spectra on a AC-200 MHz spectrometer operating
at 62.9 MHz; the multiplicity of the 13C-NMR signals
was determined by the APT technique. 119Sn{1H} NMR
spectra were recorded on a Bruker AC-200 or 400 MHz
(spectrometer frequency 74.63 or 149.21 MHz, chemical
shifts are reported in ppm (d) relative to external
Me4Sn). Mass spectra were recorded on a Nermag
R10-10H or a Hewlett Packard 5989 instrument operat-
ing, in the electron impact mode at 70 eV and samples
were contained in glass capillaries under argon. IR
Anal. Calc. for C22H17N2O5IgeW, (772.72): C, 34.19; H,
2.22; N, 3.63. Found: C, 34.03; H, 2.27; N, 3.66%.
4.4. L2(Cl)GeFe(CO)4 (6)
A toluene solution (10 ml) of L2GeCl (290 mg, 0.81
mmol) was slowly added to a suspension of Fe2(CO)9
(300 mg, 0.81 mmol) in toluene (20 ml). The reaction
mixture was then stirred at room temperature for 24 h.
The volatile materials were removed in vacuo, the
residue was dissolved in chloroform (5 ml) and the
solution was cooled at ꢁ
as yellow crystals. 6: mp 200Á
nꢀ
2043, 1969, 1947, 1923 cmꢁ1(CO). 1H-NMR (80
MHz, CDCl3): dꢀ1.97 (s, 6H, CH3), 5.50 (s, 1H, CH),
7.15Á
7.42 (m, 10H, C6H5). 13C-NMR (62.90 MHz,
CDCl3): dꢀ24.66 (s, CH3), 101.18 (s, CH), 127.65 (s,
m-aryl-C), 129.34 (s, p-aryl-C), 130.76 (s, o-aryl-C),
141.62 (s, CꢀN), 168.81 (s, Cipso), 213.14 (s, CO). MS:
(EI) m/zꢀ
526 [M]ꢂ, 498 [MꢀCO]ꢂ. Anal. Calc. for
/
30 8C to give 6 (91%, 390 mg)
/
202 8C (dec.). IR (CHCl3)
spectra were obtained on a PerkinÁ/Elmer 1600 FT-IR.
/
Irradiations were carried out at 25 8C by using a low-
pressure mercury immersion lamp in a quartz tube.
Melting points were taken on a hot-plate microscope
apparatus Leitz Biomed. Elemental analyses (C, H, N)
were performed at the ‘Microanalysis Laboratory of the
Ecole Nationale Supe´rieure de Chimie de Toulouse’.
/
/
/
/
/
/

84
I. Saur et al. / Journal of Organometallic Chemistry 672 (2003) 77Á85
/
C21H17N2O4ClFeGe, (525.26): C, 48.02; H, 3.26; N,
5.33. Found: C, 47.85; H, 3.12; N, 5.41%.
4.8. Computational details
Calculations were performed with the GAUSSIAN-98
program [17,18]. The density functional method [19]
used was the hybrid exchange functional B3LYP [20].
This functional includes a linear combination of a small
amount (20%) of exact exchange with the Becke 88
gradient-corrected exchange [20a] and with the correla-
tion energy functional LYP [20c]
4.5. L2(Cl)SnFe(CO)4 (7)
Following the same experimental procedure as for the
synthesis of 6, the reaction of L2SnCl (470 mg, 1.17
mmol) with Fe2(CO)9 (430 mg, 1.17 mmol) in 40 ml of
toluene afforded 7 (91%, 610 mg). 7: mp 132Á
(dec.). IR (CHCl3) nꢀ2044, 1969, 1950, 1928
cmꢁ1(CO). 119Sn (149.2 MHz, CDCl3): dꢀ80. 1H-
NMR (80 MHz, CDCl3): dꢀ2.03 (s, 6H, CH3), 5.31
(s, 1H, CH), 7.24Á
7.35 (m, 10H, C6H5). 13C-NMR
(62.90 MHz, CDCl3): dꢀ24.56 (s, CH3), 100.38 (s, CH),
126.22 (s, m-aryl-C), 130.12 (s, p-aryl-C), 130.02 (s, o-
aryl-C), 143.13 (s, CꢀN), 169.34 (s, Cipso), 212.40 (s,
CO). MS (EI) m/zꢀ516 [Mꢀ
2CO]ꢂ. Anal. Calc. for
/
134 8C
Exc ꢀaExHF ꢂbExLDA ꢂcExGGA ꢂdEcLDA ꢂeEcGGA
/
/
Standard parameterization has been retained (aꢀ
0.20, bꢀ1ꢁa, cꢀ0.72 for Becke exchange, eꢀ0.81
for the gradient-corrected part of the correlation energy
functional, and dꢀ1ꢁe).
/
/
/
/
/
/
/
/
/
/
The basis set retained for all calculations is the
relativistically corrected effective core potential of
Stevens et al. [21] with a double z basis expansion for
the valence space [CEP-31G(d)]. All heavy main group
atoms were augmented with a single set of polarisation
functions. For the germanium, the coefficient used is
/
/
/
C21H17N2O4ClFeSn, (571.40): C, 44.47; H, 2.99; N,
4.90. Found: C, 43.90; H, 2.82; N, 4.78%.
4.6. L2(Me)GeW(CO)5 (8)
aGd eꢀ
0.202 [22]. The optimized structures were con-
/
firmed as minima on the potential energy surface by
second-derivative calculations. The population analyses
at the given optimized geometries (Wiberg bond indices)
A toluene solution (10 ml) of L2(Cl)Geꢀ
mg, 0.076 mmol) was treated with MeLi (48 ml, 1.6 M
ether solution) at ꢁ78 8C. After the mixture was
warmed to room temperature over 3 h to give a red
solution, the solvent was removed under reduced
pressure to afford 8 as red solid (80%, 40 mg). This
/
W(CO)5 (52
/
were carried out according to the WenholdÁRedd
/
partitioning Scheme [23].
solid was recrystallized from toluene at ꢁ
obtain red crystals of 8. 8: mp 170Á172 8C. IR
(CHCl3) nꢀ
2060, 1934, 1920 cmꢁ1(CO). 1H-NMR
(80 MHz, C6D6): dꢀ0.48 (s, 3H, CH3), 1.52 (s, 6H,
CH3), 4.84 (s, 1H, CH), 7.02Á
7.36 (m, 10H, C6H5). 13C-
NMR (62.90 MHz, C6D6): dꢀ11.23 (s, CH3), 22.35 (s,
CH3), 100.97 (s, CH), 126.44 (s, m-aryl-C), 127.63 (s, p-
aryl-C), 128.56 (s, o-aryl-C), 143.99 (s, CꢀN), 166.95 (s,
ipso), 198.03 (s, CO), 200.90 (s, CO). MS (EI) m/zꢀ
CH3]ꢂ. Anal. Calc. for
/
30 8C to
5. Supplementary material
/
/
Crystallographic data (excluding structure factors)
have been deposited with the Cambridge Crystallo-
graphic Data Center, CCDC 201526-201529 for 3, 4, 6
and 7. Copies of the data can be obtained free of charge
on application to CCDC, 12 Union Road, Cambridge
/
/
/
/
CB2 1EZ, UK (fax: ꢂ44-1223-336033; e-mail deposit@
/
C
/
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
660 [M]ꢂ, 645 [Mꢀ
/
C23H20N2O5GeW, (660.85): C, 41.80; H, 3.05; N, 4.24.
Found: C, 41.76; H, 2.80; N, 4.18%.
Acknowledgements
We wish to thank Mrs G. Pfister-Guillouzo for
helpful discussions on the analysis of calculations data.
We thank the Institut du Developpement de Ressources
en Informatique Scientifique (IDRIS, Orsay, France),
administered by the CNRS, for the calculation facilities.
4.7. X-ray measurements
Crystal data for 3, 4, 6 and 7 are presented in Table 2.
80 8C)
All data were collected at low temperatures (ꢁ
/
on a Bruker-AXS CCD 1000 diffractometer with MoÁ
/
˚
0.71073 A). The structures were solved by direct
Ka (lꢀ
/
methods by means of SHELXS-97 [15] and refined with all
data on F2 by means of SHELXL-97 [16]. All non-
hydrogen atoms were refined anisotropically. The hy-
drogen atoms of the molecules were geometrically
idealized and refined using a riding model. A disorder
of the phenyl group in 7 was refined anisotropically on
two positions (54/46) with the help of ADP and
distances restraints.
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