Heterocycle-containing niobocene derivatives from hydride-niobocene complexes. X-ray molecular structure of [Cp′2Nb(CNXylyl)2][I3] and [Cp′2Nb(H)(P(OMe)3)] · (bzta)′-NH2 [(bzta)′-NH2 = 2-amino-6-methylbenzothiazole]

Article abstract of DOI:10.1016/j.jorganchem.2007.03.038

The reaction under thermal conditions of [Cp′₂Nb(H)₃] (1), Cp′ = η⁵-C₅H₄SiMe₃, with benzothiazole heterocycles, namely 2-aminobenzothiazole, bzta-NH₂, 2-hydroxybenzothiazole, bzta-OH, 2-mercaptobenzothiazole, bzta-SH, benzoxazole, namely 2-mercaptobenzoxazole, bzoa-SH, and triazines, namely 1,3,5-triaminetriazine, 1,3,5-trihydroxytriazine, 1,3,5-trimercaptotriazine, (C₃N₃)-1,3,5-(XH)₃, X = NH, O, S, yields a new family of niobocene complexes [Cp′₂Nb(κ²-X,S-Xbzta)], X = NH (2), O (3), S (4), [Cp′₂Nb(κ²-S,N-Sbzoa)] (5) and [(Cp′₂Nb)₃(κ²-X,N-X₃C₃N₃)], X = NH (6), X = O (7), X = S (8). In the same way, the thermal treatment of complex [Cp′₂Nb(H)(CNXylyl)] (9), Xylyl = C₆H₄-2,6-Me₂, with bzta-SH, bzoa-SH and (C₃H₃)-1,3,5-(SH) affords the complexes [Cp′₂Nb(κ¹-S-Sbzta)(CNXylyl)] (10), [Cp′₂Nb(κ¹-S-Sbzoa)(CNXylyl)] (11) and [{Cp′₂Nb(CNXylyl)}₃(κ¹-S-S₃C₃N₃)] (12). The reaction of compound 10 with an excess of MeI in toluene at room temperature leads to the ionic compound [Cp′₂Nb(CNXylyl)₂][I₃] (15), which contains two coordinated CNXylyl ligands and a non-coordinated I₃^- counteranion. All complexes were characterized by spectroscopic methods and the molecular structure of [Cp′₂Nb(CNXylyl)₂][I₃] (15) and [Cp′₂Nb(H)(P(OMe)₃)] · (bzta)′-NH₂ (14), an adduct of the heterocycle with the hydride-niobocene, have been determined by X-ray molecular studies.

Full text of DOI:10.1016/j.jorganchem.2007.03.038

Journal of Organometallic Chemistry 692 (2007) 3328–3339
www.elsevier.com/locate/jorganchem
Heterocycle-containing niobocene derivatives from
hydride–niobocene complexes
X-ray molecular structure of [Cp02Nb(CNXylyl)2][I3] and
[Cp02Nb(H)(P(OMe)3)] Æ (bzta)0-NH2 [(bzta)0-NH2 = 2-amino-6-
methylbenzothiazole]
*
*
´
´
Antonio Antinolo , Santiago Garcıa-Yuste, Antonio Otero , Juan C. Perez-Flores,
˜
´
´
Isabel Lopez-Solera, Ana M. Rodrıguez
Departamento de Quı´mica Inorga´nica, Orga´nica y Bioquı´mica, Facultad de Quı´mica, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain
Received 7 February 2007; received in revised form 22 March 2007; accepted 22 March 2007
Available online 31 March 2007
Abstract
The reaction under thermal conditions of [Cp02Nb(H)3] (1), Cp0 = g5-C5H4SiMe3, with benzothiazole heterocycles, namely 2-amin-
obenzothiazole, bzta-NH2, 2-hydroxybenzothiazole, bzta-OH, 2-mercaptobenzothiazole, bzta-SH, benzoxazole, namely 2-mercapto-
benzoxazole, bzoa-SH, and triazines, namely 1,3,5-triaminetriazine, 1,3,5-trihydroxytriazine, 1,3,5-trimercaptotriazine, (C3N3)-1,3,
5-(XH)3, X = NH, O, S, yields a new family of niobocene complexes [Cp02Nb(j2-X,S-Xbzta)], X = NH (2), O (3), S (4), [Cp02Nb-
(j2-S,N-Sbzoa)] (5) and [(Cp02Nb)3(j2-X,N-X3C3N3)], X = NH (6), X = O (7), X = S (8). In the same way, the thermal treatment of
complex [Cp02Nb(H)(CNXylyl)] (9), Xylyl = C6H4-2,6-Me2, with bzta-SH, bzoa-SH and (C3H3)-1,3,5-(SH) affords the complexes
[Cp02Nb(j1-S-Sbzta)(CNXylyl)] (10), [Cp02Nb(j1-S-Sbzoa)(CNXylyl)] (11) and [{Cp02Nb(CNXylyl)}3(j1-S-S3C3N3)] (12). The reaction
of compound 10 with an excess of MeI in toluene at room temperature leads to the ionic compound [Cp0 Nb(CNXylyl)2][I3] (15), which
2
contains two coordinated CNXylyl ligands and a non-coordinated I3ꢀ counteranion. All complexes were characterized by spectroscopic
methods and the molecular structure of [Cp02Nb(CNXylyl)2][I3] (15) and [Cp02Nb(H)(P(OMe)3)] Æ (bzta)0-NH2 (14), an adduct of the het-
erocycle with the hydride–niobocene, have been determined by X-ray molecular studies.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Niobium; Hydride; Niobocene; Heterocycles
1. Introduction
these systems one of the most important families is the
18 eꢀ complexes [Cp02Nb(H)L] (L = p-acid ligand) [2]. In
recent years we have focused some of our attention on
the chemistry of the hydride–isocyanide niobocenes [3] in
reactions such as insertion processes with heterocumulene
molecules [4] and alkynes [5] as well as the synthesis of
dihydrogen complexes through protonation processes [2];
in particular, this is an area in which numerous molecular
structures are still not known and it is not possible to dis-
cern between the two possible resonance forms of the coor-
dinated isocyanide, i.e., either the isocyanide or carbene
coordination mode [6] (Scheme 1).
Hydride-containing niobocene complexes are well
known and they have long been of interest for both their
high reactivity and their spectroscopic properties [1]. In
particular, the chemistry of the trihydride complex
[Cp02Nb(H)3] has been investigated in great detail and is
itself a source of new hydride–niobocene complexes; of
*
Corresponding author.
E-mail address: antonio.antinolo@uclm.es (A. Antinolo).
˜
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.03.038

A. Antin˜olo et al. / Journal of Organometallic Chemistry 692 (2007) 3328–3339
3329
carry out the reaction of this complex with new types of
heterocycles, such as benzothiazole (a), benzoxazole (b)
and triazine (c), bearing hydroxy, amino or mercapto func-
tional groups (see Chart 1). The standard reaction proce-
dure involved heating a stirred thf solution of 1 with the
corresponding heterocycle in the appropriate molar ratio.
This method allowed the isolation of the different families
of oxy-, amido- and mercapto-containing niobocene com-
plexes (Scheme 2).
M
N
R
N
C
M
C
R
Scheme 1.
Furthermore, in the field of early transition organome-
tallic chemistry, previous efforts have been directed at
studying the reactivity of amino-, hydroxy- or mercapto-
containing heterocycles towards different types of deriva-
tives of these elements. It is well known that some of these
molecules are components in many bioactive molecules [7]
and compounds of thionates and the related thiazoles are
of great interest due to their numerous commercial applica-
tions, including their use as biocides and in the environ-
mental control of toxic metals [8]. For example, some
aminopyridinato-containing complexes of groups 4 and 5
have been described [9].
Some of us have previously described examples of pyr-
imidinethiolate-containing zirconocenes [10], oxy and thio-
late pyrimidine-containing Ti and Zr species [11],
mercapto-containing Zr complexes [12] and, more recently,
a series of thiolate, amido, and oxy heterocyclic-containing
niobocene complexes [13]. As a continuation of our interest
in the chemistry of hydride–niobocenes, we report here the
reactivity of [Cp02Nb(H)3] and [Cp02Nb(H)(CNXylyl)]
towards new types of heterocycles functionalized with
hydroxy, mercapto or amino groups.
Complexes 2–8 were isolated as air-sensitive oily (2–5)
or solid (6–8) materials that are soluble in most common
organic solvents such as toluene, hexane, thf and acetone.
All the complexes described in this work were spectro-
1
scopically characterized. In the H and 13C NMR spectra
of complexes 2–8 each cyclopentadienyl ring exhibits four
and five resonances, respectively, which indicates the
presence of an asymmetrical environment for the niobium
centre. In this respect the metallacycle formed by the nio-
bium atom and the two atoms of the bidentate ligand is
proposed to be practically coplanar and would lie in the
equatorial plane that bisects the dihedral angle formed by
cyclopentadienyl rings. In addition, the NMR spectra exhi-
bit the resonances for the benzothiazole, benzoxazole and
triazine moieties, respectively (see Section 4). On the basis
of the spectroscopic data, two possible structural disposi-
tions can be proposed for complexes 2–5, as depicted
in Fig. 1, with a j2-X,N (b) or j2-X,S (a) coordination
mode.
However, in the IR spectra the position of the band cor-
responding to m(C@N) of the heterocycles appears at ca.
1590 cmꢀ1 for 2–4 and this value is near to that found in
the free ligands. On the basis of this observation, coordina-
2. Results and discussion
Following our interest in the study of the reactivity of
the trihydride complex [Cp02Nb(H)3] (1), we decided to
N
N
S
N
(a)
NH2
OH
SH
S
S
2-Aminobenzothiazole
bzta-NH2
2-Hydroxybenzothiazole
bzta-OH
2-Mercaptobenzothiazole
bzta-SH
N
(b)
(c)
SH
O
2-Mercaptobenzoxazole
bzoa-SH
NH2
OH
SH
N
N
N
N
N
N
H2N
N
NH2
HO
N
OH
HS
N
SH
2,4,6-Triamino-1,3,5-triazine
(Melamine)
2,4,6-Trihydroxy-1,3,5-triazine
(Cyanuric acid )
1,3,5-Triazine-2,4,6-trithiol
(Trithiocyanuric acid)
Chart 1. Heterocycles utilized in this study.

3330
A. Antin˜olo et al. / Journal of Organometallic Chemistry 692 (2007) 3328–3339
N
Δ
[Cp´2Nb(k2-X,S-X-bzta)]
Cp´2NbH3
1
+
XH
SH
(1)
S
-2H2
X =NH (2), O (3), S (4)
X =NH, O, S
N
O
Δ
[Cp´2Nb(k2-S,N-Sbzoa)]
(2)
Cp´2NbH3
1
+
+
-2H2
(5)
XH
Δ
N
N
[{Cp´2Nb}3(k2-X,N-X3C3N3)]
Cp´2NbH3
1
(3)
HX
N
XH
-6H2
X = NH (6), O (7), S (8)
X = NH, O, S
Scheme 2. Synthesis of complexes 2–8.
SiMe
3
H
Nb
H
H
(a)
SiMe
3
"
"
"
"
SiMe
SiMe
H
3
3
SiMe
S
3
H
S
H
(b)
(c)
Nb
Nb
Nb
Y
N
Y
N
N
+
Y
XH
Me Si
SiMe
H
3
2
SiMe
(a)
3
3
SiMe
3
H
L
Nb
SiMe
3
Scheme 3. Proposed reaction pathway for the formation of complexes 2–5.
SiMe3
SiMe3
with either j2-S,N (b) or j2-S,O (a) coordination modes. In
the IR spectrum of 5 the m(C@N) band appears at
1580 cmꢀ1 and this is significantly shifted with respect to
m(C@N) of the free heterocycle (at 1620 cmꢀ1). On this
basis a j2-S,N coordination is proposed to be present in
this complex.
N
S
X
X
S
N
Nb
Nb
For complexes 6–8 a trinuclear niobium species based
on a bidentate coordination fashion, Nb(j2-X,N), can be
considered for the appropriate triazine ligand (see Fig. 2).
These trinuclear complexes were isolated as the only
products even when niobocene:triazine molar ratios lower
than 3:1 were employed, indicating that the formation of
the trinuclear species is thermodynamically favoured.
The isolation of complexes 2–8 can be understood in
terms of the pathway depicted in Scheme 3. Step (a) corre-
sponds to the elimination of H2 to give a very reactive
SiMe3
SiMe3
X = NH, O, S
(b)
(a)
Fig. 1. Proposed structures for complexes 2–4.
tion mode (a) is proposed as the most probable. In the
same way, an analogous structural disposition may be pro-
posed for complex 5, with the benzoxazolate ligand bonded

A. Antin˜olo et al. / Journal of Organometallic Chemistry 692 (2007) 3328–3339
3331
unsaturated species would give an 18-electron hydride-het-
erocycle intermediate by coordination through the nitrogen
atoms – as proposed in step (b) for complexes 2–4. (In the
case of complex 5 the coordination of the heterocycle must
be through the oxygen atom.) Finally, elimination of a
molecule of H2 by intramolecular interaction of the hydride
ligand and the hydrogen atom of the XH moiety of the het-
erocycle would give the final complex containing a biden-
tate ligand, step (c).
X
N
[Nb]
X
N
N
[Nb]
X
[Nb]
[Nb] = Nb(η5-C5H4SiMe3)2
X = NH (6), O (7), S (8)
However, other plausible alternative pathways, e.g.
Fig. 2. Proposed structures for complexes 6–8.
+
through an initial Nb–Hꢀꢁ ꢁ ꢁ HX–R (heterocycle) interac-
tion [15], can not definitively be ruled out.
H
Cp´2Nb
In order to study the stability of the resulting four-mem-
bered metallacycle proposed in the structures of complexes
2–8, different unsuccessful insertion processes were carried
out with different types of unsaturated molecules, namely
CO, CS2, isocyanides and activated alkynes. This behav-
iour is consistent with the lack of fluxionality in solution,
which was demonstrated for these molecules by means of
CNXylyl
SH
N
(9)
SH
1/3
N
N
Δ
-6 H2
Y
HS
N
SH
Δ
Y= S , O
-2H2
1
[Nb]
variable-temperature H NMR studies.
S
Y
N
Furthermore, in relation to our interest in studying new
isocyanide-niobocene systems we carried out reactivity
studies on the 18-electron d2 niobocene complex [Cp02Nb
(H)(CNXylyl)] (9) towards some of the aforementioned
heterocycles (see Scheme 4). In fact, reactions of 9 with
bzta-SH, bzoa-SH or (C3N3)-1,3,5-(SH)3 in thf
in the appropriate molar ratios led to the isolation of
new complexes 10–12 after the appropriate work-up
procedure.
S
L
Cp2`Nb
L
N
N
CNXylyl
[Nb]
S
N
L
S
Y = S (10); Y = O (11)
[Nb]
[Nb] = Nb(η5-C5H4SiMe3)2
(12)
L = CNXylyl
Scheme 4. Reactions for the formation of complexes 10–12.
Complexes 10–12 were isolated as air-sensitive oily (10–
11) or solid (12) products and they were soluble in most
common organic solvents such as toluene, hexane, thf
and acetone.
16-electron monohydride niobocene intermediate, which
has previously been proposed by us in several processes
[14]. Coordination of the corresponding heterocycle to this
"
SiMe3
"
SiMe3
SiMe3
δ-
δ+
Y
-H2
H
L
S
H
S
H
Nb
Y
Nb
Nb
N
L
N
L
HS
Y
N
SiMe3
SiMe3
SiMe3
L = CNXylyl (9);
L = CNXylyl,
Y = S (10); Y = O (11);
HS
Y
N
Y
XH
N
X = S, Y = S;
X = S, Y = O;
Scheme 5. Proposed reaction pathway for the formation of complexes 10–11.

3332
A. Antin˜olo et al. / Journal of Organometallic Chemistry 692 (2007) 3328–3339
In accordance with the lack of symmetry in the pro-
the lower stability of the Nb–P(OMe)3 bond in comparison
to the Nb–CNR one.
1
posed structures, the H and 13C NMR spectra of these
complexes exhibit four (or three) and five resonances for
each cyclopentadienyl ring, respectively. The carbon reso-
nances for the CNXylyl ligand in 10–12 appear at d
215.2, 206.2 and 209.8, respectively. In these complexes a
j1-S coordination mode for the heterocyclic ligand is
proposed.
The formation of complexes 10–12 can be understood in
terms of an acid–base process where in a first step a Nb–H
bond interacts with the H–S moiety of the benzothiazole,
benzoxazole or triazine. This is followed by the elimination
of H2 and the subsequent formation of the corresponding
thiolate-containing complexes (see Scheme 5). It is notewor-
thy that under our experimental conditions a possible final
step correspondingto the de-coordination of the appropriate
auxiliary ligand, namely CNXylyl, and the formation of a
chelate j2-S,X-heterocyclic-containing niobocene was not
observed. This behaviour is in accordance with the previ-
ously observed high stability of the Nb–CNR bonds in this
class of 18-electron d2 niobocene species [16].
Furthermore, it has been observed that the heterocycles-
containing amino or hydroxy functionality, namely bzta-
NH2 and (C3N3)-1,3,5-(NH2)3, bzta-OH, bzta-NH2 and
(C3N3)-1,3,5-(OH)3, do not react with complex 9 even at
100 ꢁC. This behaviour is probably due to the lower acidity
of the NH2 or OH group in comparison to the SH group in
bzta-SH and (C3N3)-1,3,5-(SH)3. However, when
[Cp02Nb(H)(P(OMe)3)] (13) is reacted with bzta-SH, bzta-
OH, bzta-NH2, bzoa-SH, (C3N3)-1,3,5-(SH)3, (C3N3)-
1,3,5-(OH)3 or (C3N3)-1,3,5-(NH2)3 in toluene at 100 ꢁC,
the reaction gave complexes 2–8 by elimination of hydro-
gen and P(OMe)3. This behaviour can be explained in
terms of prior coordination of the heterocyclic ligand to
the unsaturated niobium intermediate obtained by the ther-
mal elimination of the P(OMe)3 followed by hydrogen
elimination (see Scheme 3); this proposal is consistent with
In
a
parallel experiment, complex [Cp02Nb(H)
(P(OMe)3)] (13) was treated with 2-amino-6-methylbenzo-
thiazole, (bzta)0-NH2, in a 1:1 molar ratio at 65 ꢁC during
36 h. However, under these conditions a reaction did not
take place. When the solution in toluene was kept at room
temperature during two weeks a red microcrystalline mate-
rial was obtained and this corresponds to the adduct
[Cp02Nb(H)(P(OMe)3)] Æ (bzta)0NH2 (14) (see X-ray diffrac-
tion study).
In addition, further reaction of CH3I with 10 gave the
cationic bis(isocyanide)niobocene triiodide complex
[Cp02Nb(CNXylyl)2][I3] (15) (Scheme 6) rather than the
expected niobocene-containing N-alkylated or S-alkylated
ligand [17] (Scheme 7).
Complex 15 was isolated as an air-sensitive red solid and
is soluble in organic solvents such as toluene, thf and ace-
tone. This complex contains the same cation as the com-
plex [Cp02Nb(CNXylyl)2][HB(C6F5)3] reported by some of
us [13] in an acid–base process involving 9 with B(C6F5)3
in the presence of CNXylyl. The geometry proposed for
the structure of 15 (see Scheme 6) is consistent with the
1H and 13C NMR spectra of this complex. The spectra
exhibit two and three resonances for each cyclopentadienyl
ring, respectively. The carbon resonance for the CNXylyl
ligand appears at d 226.1. Furthermore, signals corre-
sponding to the heterocyclic ligand are absent from the
spectra, indicating the loss of this unit during the process.
Suitable crystals of 15 for an X-ray crystal structure study
were obtained.
2.1. X-ray diffraction study of [Cp02Nb(CNXylyl)2][I3]
(15)
The molecular structure of complex 15 was determined
by X-ray diffraction. The ORTEP diagram is shown in
SiMe3
SiMe3
-
I
3
S
N
CNXylyl
Nb
S
Nb
CNXylyl
+ Me I excess
CNXylyl
SiMe3
(15)
(10)
SiMe3
Scheme 6. Reaction process for the formation of complex 15.
Me
Me
S
N
S
N
S
N
Nb
S
Nb
S
S
Nb
-
-
-
I
I
I
Me
II
I
III
Scheme 7. Potential alkylation products from complex 10 using MeI.

A. Antin˜olo et al. / Journal of Organometallic Chemistry 692 (2007) 3328–3339
3333
Fig. 3. To the best of our knowledge, the number of isocy-
anideniobiocene complexes characterized by X-ray crystal-
lography is not very large [18]. Selected bond distances and
bond angles are listed in Table 1.
and the two isocyanide ligands occupy the other two coor-
dination sites in a distorted tetrahedral geometry. The ori-
entation of the two Cp0 rings is intermediate between
eclipsed and staggered positions, with Si(1)–Cent(1)–
Cent(2)–Si(2) angles of 168.1ꢁ and 174.6ꢁ, respectively.
The values of the Cent(1)–Nb(1)–Cent(2) angles of
138.5(9)ꢁ and 137.5(9)ꢁ are typical of these bent niobocene
There are two molecules in the asymmetric unit cell and
the structure consists of monomeric cations [Cp02Nb
ꢀ
(CNXylyl)2]+ and H-bonded I3 anions. The cation struc-
˚
ture is typical of bent metallocenes. The niobium atom is
derivatives. The C–N bond lengths of 1.17(3) and 1.17(2) A
coordinated to both cyclopentadienyl rings in a g5-mode
for molecule 1 and 1.14(3) and 1.19(2) A for molecule 2 are
˚
consistent with the presence of a carbon–nitrogen triple
bond [19]. The C(1)–N(1)–C(31) angles of 176(3)ꢁ and
C(2)–N(2)–C(41) angles of 172(2) and 174(2)ꢁ for mole-
cules 1 and 2, respectively, clearly indicate the linearity of
the isocyanide ligand. These values confirm the back dona-
tion of the niobium(III) d2 centre to the isocyanide ligand,
with a triple bond remaining between the C and N but, in
these cases, the contribution of the carbene form in the
interaction with the niobium centre is small (see Scheme
1). The results of this analysis are in agreement with the
IR data in solution (see Section 4).
The triiodide anion bond distances are practically equiv-
˚
alent, with values between 2.851(3) and 2.980(3) A, and the
angles between the three iodide atoms of 179.4(1) and
175.6(1)ꢁ, respectively, are in agreement with a linear
disposition.
The crystal is stabilized by weak hydrogen bonding
interactions between the triiodide anions and niobocene
cations (Table 2, Fig. 4).
2.2. X-ray diffraction study of
[Cp02Nb(H)(P(OMe)3)] Æ (bzta)0-NH2 (14)
Fig. 3. Molecular structure and atom-labelling scheme for complex 15,
with thermal ellipsoids at 20% probability. Hydrogen atoms are omitted
for clarity.
The molecular structure of 14 was determined by X-ray
diffraction. A few X-ray molecular structures of hydride–
niobocene complexes have been reported [5,20] although
this is the first X-ray study on a hydride–phosphite niobo-
cene complex. The molecular structure and atomic num-
bering scheme are shown in Fig. 5. Selected bond lengths
and angles for 14 are given in Table 3.
Table 1
˚
Bond lengths (A) and angles (ꢁ) for 15
Bond lengths
ꢀ
Nb(1)–C(1)
Nb(1)–C(2)
Nb(1)–Cent(1)
Nb(1)–Cent(2)
N(1)–C(1)
N(1)–C(31)
N(2)–C(2)
N(2)–C(41)
I(1)–I(2)
2.11(3)
2.10(2)
2.072(2)
2.072(2)
1.17(3)
1.41(3)
1.17(2)
1.44(2)
2.916(3)
2.908(3)
2.16(2)
2.08(2)
2.043(2)
2.067(2)
1.14(3)
1.46(3)
1.19(2)
1.36(2)
2.851(3)
2.980(3)
The complex crystallizes in the triclinic space group P1,
with a complex molecule, [Cp02Nb(H)(P(OMe)3)] and a
non-coordinated molecule of (bzta)0-NH2 in the asymmet-
ric unit cell. The solid-state molecular structure essentially
consists of two niobium centres held by (amine)N–Hꢁ ꢁ ꢁO
and (amine)N–Hꢁ ꢁ ꢁ(heterocyclic)N hydrogen bonds (see
Supplementary Material).
The niobium atom is coordinated to both cyclopentadie-
nyl rings in a g5-mode, to the P of the P(OMe)3 and to the
hydride in a distorted tetrahedral geometry. The Nb(1)–
I(2)–I(3)
Angles
C(1)–Nb(1)–C(2)
Cent(1)–Nb(1)–Cent(2)
Nb(1)–C(1)–N(1)
C(1)–N(1)–C(31)
Nb(1)–C(2)–N(2)
C(2)–N(2)–C(41)
I(1)–I(2)–I(3)
83.5(9)
138.5(9)
179(2)
176(3)
177(2)
172(2)
179.4(1)
83.2(8)
137.5(9)
177(2)
176(3)
178(2)
174(2)
175.6(1)
˚
H(1) bond distance of 1.63(6) A is normal for the
hydride–niobium bond [21] and the Nb(1)–P(1) bond dis-
tance of 2.491(2) A is shorter than the phosphine–niobium
˚
bond distances but similar to other phosphide–niobium
bond distances [22].
The two Cp0 rings show an eclipsed orientation, with a
Si(1)–Cent(1)–Cent(2)–Si(2) angle of 70.6(1)ꢁ. The value
of the Cent(1)–Nb(1)–Cent(2) angle is 143.28(4)ꢁ, which
Cent(1) is the centroid of C(11)–C(15) and Cent(2) is the centroid of
C(21)–C(25).

3334
A. Antin˜olo et al. / Journal of Organometallic Chemistry 692 (2007) 3328–3339
Table 2
Hydrogen bonds for compound 15
D–Hꢁ ꢁ ꢁA
d(D–H) (A)
d(Dꢁ ꢁ ꢁA) (A)
\DHA (ꢁ)
d(Dꢁ ꢁ ꢁA) (A)
Symmetrya
˚
˚
˚
C(47A)–H(47E)ꢁ ꢁ ꢁI(1)
C(12A)–H(12A)ꢁ ꢁ ꢁI(2A)
C(25A)–H(25A)ꢁ ꢁ ꢁI(2A)
C(22)–H(22)ꢁ ꢁ ꢁI(3A)
0.96
0.93
0.93
0.93
0.93
3.17
3.21
3.21
3.22
3.11
145.9
138.3
135.5
143.7
139.0
4.00(2)
3.95(2)
3.93(2)
4.01(2)
3.86(3)
x, y, z
x, y, z
x, y, z
x, y ꢀ 1, z
C(35A)–H(35A)ꢁ ꢁ ꢁI(3A)
1 ꢀ x, 1 ꢀ y, 1 ꢀ z
a
Symmetry operation for A.
Fig. 4. Packing plot of 15. The triiodide anion is hydrogen bonded to niobocene complex (dotted lines).
Fig. 5. Molecular structure and atom-labelling scheme for complex 14, with thermal ellipsoids at 30% probability. Hydrogen atoms are omitted for clarity.
is typical of bent niobocene derivatives, and the dihedral
angle between the two Cp0 rings is 43.0(3)ꢁ.
through the other hydrogen of the amino group (N2–
H2ꢁ ꢁ ꢁN1) (Table 4).
Although it is quite difficult to crystallize this class of
hydride–niobocene complex, in our example the interac-
tions between the (bzta)0-NH2molecule and the hydride–
niobocene complex probably contribute to stabilize the
crystal. As a result, the formation of a dimer can be
observed in the structure as a consequence of several inter-
molecular hydrogen bonding interactions (Fig. 6).
The amine group shows a bifurcated hydrogen bond
with two oxygen atoms from the phosphite (N2–H3ꢁ ꢁ ꢁO1
and N2–H3ꢁ ꢁ ꢁO2). This kind of interaction has only been
reported once before [23]. Furthermore, there is another
hydrogen bond between two heterocyclic molecules
3. Conclusions
We have studied the reactivity of the niobocene trihy-
dride 1 towards bzta-SH, bzta-NH2, bzta-OH, bzoa-SH
and triazines, (C3N3)-1,3,5-(XH)3, X = NH, O, S, to pro-
duce new families of heterocycle-containing niobocene
derivatives 2–8. We have also prepared new niobocene
complexes 10, 11 and 12, which contain isocyanide as an
ancillary ligand and the appropriate heterocycle, starting
from the hydride–isocyanide niobocene 9 and bzta-SH,
bzoa-SH or (C3N3)-1,3,5-(SH)3. The X-ray molecular

A. Antin˜olo et al. / Journal of Organometallic Chemistry 692 (2007) 3328–3339
3335
Table 3
structures of two complexes (14 and 15) were determined,
with 15 being a representative member of a small family
of early transition metallocenes bearing an isocyanide
ancillary ligand.
˚
Bond lengths (A) and angles (ꢁ) for 14
Bond lengths
Nb(1)–P(1)
Nb(1)–H(1)
Nb(1)–Cent(1)
Nb(1)–Cent(2)
P(1)–O(3)
P(1)–O(2)
P(1)–O(1)
O(1)–C(1)
O(2)–C(2)
2.491(2)
1.63(6)
2.053(1)
2.046(1)
1.595(5)
1.618(4)
1.619(4)
1.423(8)
1.434(8)
1.458(8)
1.737(6)
1.756(6)
1.311(7)
1.390(8)
1.321(8)
4. Experimental
4.1. General procedures
All reactions were carried out using Schlenk techniques.
Oxygen and water were excluded by the use of vacuum
lines supplied with purified N2. Toluene was distilled from
sodium. Pentane was distilled from sodium/potassium
alloy. Diethyl ether and thf were distilled from sodium ben-
zophenone. All solvents were deoxygenated prior to use.
Complexes [Cp02Nb(H)3] (1), [Cp02Nb(H)(CNXylyl)] (9)
and [Cp02Nb(H)(P(OMe)3)] (13) were prepared as
described in the literature [24,2a]. Deuterated solvents were
O(3)–C(3)
S(1)–C(32)
S(1)–C(30)
N(1)–C(30)
N(1)–C(31)
N(2)–C(30)
Angles
Cent(1)–Nb(1)–Cent(2)
Cent(1)–Nb(1)–P(1)
Cent(2)–Nb(1)–P(1)
O(3)–P(1)–O(2)
O(3)–P(1)–O(1)
O(2)–P(1)–O(1)
O(3)–P(1)–Nb(1)
O(2)–P(1)–Nb(1)
O(1)–P(1)–Nb(1)
C(1)–O(1)–P(1)
C(2)–O(2)–P(1)
C(3)–O(3)–P(1)
143.28(4)
110.73(5)
101.48(5)
102.1(3)
103.1(3)
89.1(2)
116.6(2)
118.3(2)
122.9(2)
123.4(4)
120.1(4)
120.8(4)
89.4(3)
˚
dried over 4 A molecular sieves and degassed prior to use.
The different heterocycles, namely benzothiazole, benzox-
azole and triazine were used as purchased from Aldrich.
NMR spectra were recorded on a Varian Unity 300
(300 MHz for 1H, 75 MHz for 13C) spectrometer. Chemical
shifts were measured relative to partially deuterated solvent
peaks and are reported relative to TMS. IR spectra were
recorded on a Perkin–Elmer 883 spectrophotometer in
Nujol mulls over CsI windows.
C(32)–S(1)–C(30)
C(30)–N(1)–C(31)
H4
109.8(5)
Cent(1) is the centroid of C(11)–C(15) and Cent(2) is the centroid of
C(21)–C(25).
H5
C4
N
Y
C5
C6
C3'
C7'
C2
XH
H6
C7
H7
Y = S; X = NH, (2); O, (3); S, (4)
Y = O; X = S, (5)
4.2. Synthesis of [Cp02Nb(j2-X,S-Xbzta)], X = NH (2), O
(3), S (4)
The complex [Cp02Nb(H)3] (1) (0.75 g; 2.25 mmol) was
dissolved in 30 mL of dry thf and to this solution was
added NH2-bzta in a 1:1 stoichiometry (0.34 g; 70 mmol).
The mixture was stirred at 343 K for 5 h. The resulting
dark-red solution was filtered and evaporated to dryness.
Fig. 6. Two asymmetric units of 14 (H-bonded) are shown. Only
hydrogen atoms involved in hydrogen bonding are drawn.
Table 4
Hydrogen bonds for compound 14
N–Hꢁ ꢁ ꢁ
A
d(N–H) (A)
d(Hꢁ ꢁ ꢁA) (A)
\NHA (ꢁ)
d(Nꢁ ꢁ ꢁA) (A)
Symmetrya
˚
˚
˚
N(2)–H(2)ꢁ ꢁ ꢁN(1)
N(2)–H(3)ꢁ ꢁ ꢁO(1)
N(2)–H(3)ꢁ ꢁ ꢁO(2)
0.91 (2)
0.73 (3)
0.73 (3)
2.07 (4)
2.47 (1)
2.36 (1)
176.9 (2)
140.5 (1)
159.5 (1)
2.97 (2)
3.07 (3)
3.05 (1)
ꢀx, ꢀy, 1 ꢀ z
x ꢀ 1, y, z
x ꢀ 1, y, z
a
Symmetry operation for A.

3336
A. Antin˜olo et al. / Journal of Organometallic Chemistry 692 (2007) 3328–3339
Complex 2 was obtained as a dark red oil from a saturated
hexane solution at ꢀ30 ꢁC (0.30 g; 90%). Complexes 3 and
4 were prepared in a similar manner to 2 (86% and 88%
yield, respectively).
not possible, C5H4SiMe3), 109.6 (C1, C5H4SiMe3), 113.6,
122.6 (C4–7 aromatic system of bzoa), 124.1 (C5-6 aromatic
0
system of bzoa), 140.9 (C3 aromatic system of bzoa), 149.9
0
(C7 aromatic system of bzoa), 181.1 (C2 aromatic system
of bzoa).
Complex 2: IR (Nujol/PET cmꢀ1) m (N–H); 3230,
1
(C@N) 1615. H NMR (C6D6): d 0.02 (s, 18H, SiMe3),
3.18 (s, 1H, N–H), 4.15, 4.20, 5.19, 5.59 (2H each a com-
plex signal, C5H4SiMe3), 6.69, 6.63 (1H each t,
3JHH = 7 Hz, H5, H6 aromatic system of bzta), 7.35, 7.68
(1H each d, 3JHH = 7 Hz, H4, H7 aromatic system of bzta).
13C {1H} NMR (C6D6): d 0.8 (SiMe3), 94.3 (C1,
C5H4SiMe3), 102.0, 103.4, 104.1, 112.0 (C2–5, exact assign-
ment not possible, C5H4SiMe3), 122.1 (C5–6 aromatic sys-
tem of bzta), 123.2, 123.6 (C4–7 aromatic system of bzta),
4.4. Synthesis of [(Cp02Nb)3(j2-X,N-X3(C3N3))],
X = NH (6), O (7), S (8)
A mixture of [Cp02Nb(H)3] (1) (0.75 g; 2.25 mmol) and
the corresponding triazine C3N3(XH)3 (where X = NH,
O, S) in a 3:1 stoichiometry (0.75 mmol; 0.09, 0.09,
0.13 g, respectively) was stirred with 30 mL of dry thf at
343 K for 4 h. After that time the solution was dark green
in colour; the solvent was evaporated under vacuum to dry-
ness. The dark green oily residue was extracted with 10 mL
of cold hexane. The resulting solution was filtered and
evaporated to dryness. A dark green solid was isolated,
yielding 90% of 6. Complexes 7 and 8 were prepared in a
similar way.
0
0
146.3 (C3 aromatic system of bzta), 172.3 (C7 aromatic
system of bzta), 182.1 (C2 aromatic system of bzta).
Complex 3: IR (Nujol/PET cmꢀ1) m (C@N) 1583. H
1
NMR (C6D6): d 0.04 (s, 18H, SiMe3), 4.30, 4.37, 5.25,
5.95 (2H each a complex signal, C5H4SiMe3), 6.80, 6.91
3
(1H each t, JHH = 7.3 Hz, H5, H6 aromatic system of
bzta), 7.43, 7.70 (1H each d, 3JHH = 7 Hz, H4, H7 aromatic
system of bzta). 13C {1H} NMR (C6D6): d 0.8 (SiMe3), 89.3
(C1, C5H4SiMe3), 97.8, 99.9, 103.8, 104.7 (C2–5, exact
assignment not possible, C5H4SiMe3), 125.1, 126.3 (C5–6
aromatic system of bzta0), 128.5, 129.3 (C4–7 aromatic sys-
Complex 6: IR (Nujol/PET cmꢀ1) m (N–H) 3200. H
1
NMR (C6D6): d 0.12 (s, 54H, SiMe3), 2.3 (s, 3H, N–H),
4.11, 4.14, 5.35, 5.48 (6H each a complex signal,
C5H4SiMe3). 13C {1H} NMR (C6D6): d 0.7 (SiMe3), 87.8
(C1, C5H4), 97.6, 98.8, 103.4, 104.6 (C2–5, exact assignment
not possible, C5H4SiMe3), 172.7 [Cipso, (NH)3C3N3]. Anal.
Calc. for C51H84N6Nb3Si6: C, 49.86; H, 6.89; N, 6.84.
Found: C, 49.75; H, 6.85; N, 6.79%.
tem of bzta), 132.5 (C3 aromatic system of bzta), 157.5
0
(C7 aromatic system of bzta), 176.3 (C2 aromatic system
of bzta).
1
1
Complex 4: IR (Nujol/PET cmꢀ1) m (C@N) 1629. H
Complex 7: H NMR (C6D6): d ꢀ0.01 (s, 54H, SiMe3),
NMR (C6D6): d 0.05 (s, 18H, SiMe3), 4.15, 4.71, 5.19,
3.84, 4.10, 5.43, 5.73 (6H each a complex signal,
C5H4SiMe3). 13C {1H} NMR (C6D6): d 0.7 (SiMe3), 91.2
(C1, C5H4), 102.2, 103.7, 105.3, 106.5 (C2–5, exact assign-
ment not possible, C5H4SiMe3), 178.2 [Cipso, (O)3C3N3].
Anal. Calc. for C51H81N3Nb3O3Si6: C, 49.74; H, 6.63; N,
3.41. Found: C, 49.70; H, 6.59; N, 6.33%.
5.40 (2H each a complex signal, C5H4SiMe3), 6.72, 6.92
3
(1H each t, JHH = 7.2 Hz, H5, H6 aromatic system of
bzta), 7.39, 8.10 (1H each d, 3JHH = 8 Hz, H4, H7 aromatic
system of bzta). 13C {1H} NMR (C6D6): d 1.1 (SiMe3), 89.8
(C1, C5H4SiMe3), 98.1, 100.2, 103.9, 105.9 (C2–5, exact
assignment not possible, C5H4SiMe3), 120.3, 120.4 (C5–6
aromatic system of bzta0), 122.2, 126.6 (C4–7 aromatic sys-
1
Complex 8: H NMR (C6D6): d 0.10 (s, 54H, SiMe3),
4.27, 4.79, 4.92, 5.60 (6H each a complex signal,
C5H4SiMe3). 13C {1H} NMR (C6D6): d 0.6 (SiMe3), 93.7
(C1, C5H4), 94.1, 99.9, 101.7, 107.0 (C2-5, exact assignment
not possible, C5H4SiMe3), 196.6 [Cipso, (S)3C3N3]. Anal.
Calc. for C51H81N3Nb3S3Si6: C, 47.87; H, 6.39; N, 3.28.
Found: C, 47.79; H, 6.35; N, 3.25%.
tem of bzta), 128.2 (C3 aromatic system of bzta), 142.2
0
(C7 aromatic system of bzta), 173.7 (C2 aromatic system
of bzta).
4.3. Synthesis of [Cp02Nb(j2-S,N-Sbzoa)] (5)
The complex [Cp02Nb(H)3] (1) (0.75 g; 2.25 mmol) was
dissolved in 30 mL of dry thf and to this solution was
added bzoa-OH in a 1:1 stoichiometry (0.34 g; 70 mmol).
The mixture was stirred at 343 K for 3 h. The resulting
dark-red solution was filtered and evaporated to dryness.
Complex 2 was obtained as a dark red oil from a saturated
hexane solution at ꢀ30 ꢁC (0.30 g; 85%).
4.5. Synthesis of [Cp02Nb(j1-S-Sbzta)(L)], L = CNXylyl
(10)
A mixture of complex 9 (0.75 g; 2.25 mmol) and bzta-
SH (0.38 g; 2.25 mmol) was stirred with 30 mL of dry thf
at room temperature for 3 h. After that time, the solution
was green in colour. The solvent was evaporated under vac-
uum to dryness and the green oily residue was extracted
with 10 mL of hexane. The resulting solution was filtered
and evaporated to dryness. A green oil was isolated, yield-
ing 85% of 10.
1
Complex 5: IR (Nujol/PET cmꢀ1) m (C@N) 1580. H
NMR (C6D6): d 0.04 (s, 18H, SiMe3), 4.06, 4.36, 5.40,
5.45 (2H each a complex signal, C5H4SiMe3), 6.70, 6.80
3
(1H each t, JHH = 7.5 Hz,, H5, H6 aromatic system of
3
bzoa), 7.62, 7.80 (1H each d, JHH = 7.3 Hz, H4, H7 aro-
Complex 10: IR (Nujol/PET cmꢀ1) m (C„N) 2060,
matic system of bzoa). 13C {1H} NMR (C6D6): d 0.6
(SiMe3), 96.8, 99.4, 103.5, 104.6 (C2–5, exact assignment
(C@N) 1585. H NMR (C6D6): d 0.08 (s, 18H, SiMe3),
1
2.22 (s, 6H, C6H3-2,6-Me2), 5.06 (m, 4H, a complex signal,

A. Antin˜olo et al. / Journal of Organometallic Chemistry 692 (2007) 3328–3339
3337
C5H4SiMe3), 5.45, 5.70 (2H each a complex signal,
101.0 (C1, C5H4), 95.8, 101.9, 103.5, 104.9 (C2–5, exact
assignment not possible, C5H4SiMe3), 127.5, 128.3,133.5
(C1–6, exact assignment not possible, C6H3-2,6-Me2),
174.7 [Cipso, (S)3C3N3], 209.8 (C„N). Anal. Calc. for
C100H108N6Nb3S3Si6: C, 61.99; H, 5.62; N, 4.34. C, 61.92;
H, 5.58; N, 4.30.
3
C5H4SiMe3), 6.57, 6.88 (1H each t, JHH = 7.2 Hz, H5,
H6 aromatic system of bzta), 7.26, 7.67 (1H each d,
3JHH = 7 Hz, H4, H7 aromatic system of bzta), 6.75 (s,
3H, C6H3-2,6-Me2). 13C {1H} NMR (C6D6): d 0.8 (SiMe3),
20.0 (C6H3-2,6-Me2), 96.2 (C1, C5H4), 96.9, 101.8, 105.2,
107.3 (C2–5, exact assignment not possible, C5H4SiMe3),
120.6, 120.7, 124.0, 133.8 (C1–6, exact assignment not pos-
sible, C6H3-2,6-Me2), (Cortho of Xylyl), (C1 of Xylyl), 123.9,
4.8. Synthesis of [Cp02Nb(CNXylyl)2][I3] (15)
126.0 (C5–6 aromatic system of bzta), 127.8, 129.2 (C4–7
To a solution of 11 (0.25 g; 2.25 mmol) in 30 mL of tol-
uene was added MeI (25 mmol). The mixture was stirred
for 4 h at 60 ꢁC and, after this time, the solution was red
in colour. The solvent was evaporated under vacuum to
dryness. A red solid was formed by addition of 10 mL of
diethyl ether. The red solid was isolated by filtration and
evaporated to dryness. A red solid was isolated, yielding
38% of 15.
0
aromatic system of bzta), 139.1 (C3 aromatic system of
0
bzta), 156.3 (C7 aromatic system of bzta), 185.4 (C2 aro-
matic system of bzta), 215.2 (C„N).
4.6. Synthesis of [Cp02Nb(j1-S-Sbzoa)(CNXylyl)] (11)
A
mixture of [Cp02Nb(H)(XylylNC)] (9) (1.12 g;
1
2.25 mmol) and bzoa-SH (0.34 g; 2.25 mmol) was stirred
with 30 mL of dry thf at 60 ꢁC for 4 h. After this time,
the solution was green in colour. The solvent was evapo-
rated under vacuum to dryness and the green oily residue
was extracted with 10 mL of hexane. The resulting solution
was filtered and evaporated to dryness. A red oil was iso-
lated, yielding 90% of 11.
Complex 15: IR (Nujol/PET cmꢀ1) m (C„N) 2124. H
NMR (Acetone–d 6): d 0.25 (s, 18H, SiMe3), 2.46 (s, 6H,
C6H3-2,6-Me2), 5.74, 5.99 (4H each a complex signal,
C5H4SiMe3), 7.24 (m, 3H, C6H3-2,6-Me2). 13C {1H}
Table 5
Crystal data and structure refinement for 15 and 14
15
14
Complex 11: IR (Nujol/PET cmꢀ1) m (C„N) 2050,
1
Empirical formula
Formula weight
Temperature (K)
Wavelength (A)
Crystal system
Space group
C34H44I3N2NbSi2 C19H36NbO3PSi2 · C8H8N2S
(C@N) 1565. H NMR (C6D6): d 0.00 (s, 18H, SiMe3),
1010.5
656.76
2.14 (s, 6H, C6H3-2,6-Me2), 4.95, 5.00, 5.42, 5.60 (2H each
a complex signal, C5H4SiMe3), 6.59, 6.90 (1H each t,
3JHH = 7 Hz, H5, H6 aromatic system of bzoa), 7.00, 7.54
250(2)
230(2)
˚
0.71073
Triclinic
0.71073
Triclinic
3
(1H each d, JHH = 7.5 Hz, H4, H7 aromatic system of
ꢀ
ꢀ
P1
P1
˚
bzoa), 6.53 (s, 3H, Harom of Xylyl). 13C {1H} NMR
(C6D6): d 0.2 (SiMe3), 19.1 (C6H3-2,6-Me2), 95.3 (C1,
C5H4), 94.4, 100.2, 105.1, 105.6 (C2–5, exact assignment
not possible, C5H4SiMe3), 108.6, 109.4, 111.5, 116. 7 (C1–
6, exact assignment not possible, C6H3-2,6-Me2), 122.1,
a (A)
9.452(1)
19.570(1)
23.024(1)
71.54(1)
87.25(1)
78.95(1)
3964.5(5)
4
10.167(3)
12.191(2)
13.886(1)
71.713(3)
86.155(5)
81.095(2)
1614.2(6)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
122.8 (C5–6 aromatic system of bzoa), 123.3, 124.1 (C4–7
Volume (A )
0
Z
aromatic system of bzoa), 132.4 (C3 aromatic system of
Dcalc (g/cm3)
Absorption
coefficient (mmꢀ1
F(000)
1.693
2.724
1.351
0.591
0
bzoa), 155.9 (C7 aromatic system of bzoa), 190.3 (C2 aro-
matic system of bzoa), 206.2 (C„N).
)
1960
688
4.7. Synthesis of [{Cp02Nb(CNXylyl)}3(j1-S-S3C3N3)]
(12)
Crystal size (mm)
h Range for data
collection (ꢁ)
0.3 · 0.3 · 0.1
1.12–25.01
0.3 · 0.2 · 0.1
2.03–28.02
Index ranges
ꢀ11 6 h 6 11
ꢀ22 6 k 6 23
0 6 l 6 27
ꢀ13 6 h 6 13
ꢀ15 6 k 6 16
0 6 l 6 18
A
mixture of [Cp02Nb(H)(XylylNC)] (9) (1.12 g;
2.25 mmol) and the triazine C3N3(SH)3 with a 3:1 stoichi-
ometry, (0.13 g; 0.75 mmol). was stirred with 30 mL of
dry thf at 60 ꢁC for 4 h. After that time, the solution was
green in colour. The solvent was evaporated under vacuum
to dryness and the green oily residue was extracted with
10 mL of hexane. The resulting solution was filtered and
evaporated to dryness. A green oil was isolated, yielding
90% of 12.
Reflections collected
Independent
reflections
Data/restraints/
parameters
Goodness-of-fit on F2 0.928
Final R indices
[I > 2r(I)]
R indices (all data)
14317
13932
[Rint = 0.1130]
13932/0/762
8096
7780 [Rint = 0.0767]
7780/0/356
1.054
R1 = 0.0875,
R1 = 0.0683, wR2 = 0.1430
wR2 = 0.1665
R1 = 0.3602,
wR2 = 0.2466
0.918/ꢀ1.186
Complex 12: IR (Nujol/PET cmꢀ1) m (C„N) 2050. H
1
R1 = 0.1596, wR2 = 0.1726
0.818/ꢀ0.983
NMR (C6D6): d 0.10 (s, 54H, SiMe3), 1.99 (s, 18H,
C6H3-2,6-Me2), 4.82, 4.91, 5.37, 5.48 (6H each a complex
signal, C5H4SiMe3) 6.72 (m, 9H, Harom of Xylyl). 13C
{1H} NMR (C6D6): d ꢀ0.2 (SiMe3), 18.9 (C6H3-2,6-Me2),
Largest difference in
peak and hole
ꢀ3
˚
(e A
)

3338
A. Antin˜olo et al. / Journal of Organometallic Chemistry 692 (2007) 3328–3339
(b) A. Antinolo, F. Carrillo-Hermosilla, A. Castel, M. Fajardo, J.
Fernandez-Baeza, M. Lanfranchi, A. Otero, M.A. Pellinghelli, G.
˜
NMR (C6D6): d ꢀ0.0 (SiMe3), 19.1 (C6H3-2,6-Me2), 98.1
(C1, C5H4), 97.2, 102.2 (C2–5, exact assignment not possi-
ble, C5H4SiMe3), 127.5, 128.3, 133.5 (C1–6, exact assign-
ment not possible, C6H3-2,6-Me2), 226.1 (C„N). Anal.
Calc. for C34H35I3N2NbSi2: C, 40.78; H, 3.52; N, 2.80.
Found: C, 40.70; H, 3.48; N, 2.75%.
Rima, J. Satge, E. Villasenor, Organometallics 17 (1998) 1523;
˜
(c) A. Antinolo, F. Carrillo-Hermosilla, B. Chaudret, M. Fajardo, S.
˜
Garcia-Yuste, F.J. Lahoz, M. Lanfranchi, J.A. Lopez, A. Otero,
M.A. Pellinghelli, Organometallics 14 (1995) 1297.
´
´
[3] A. Antinolo, D. Evrard, S. Garcıa-Yuste, A. Otero, J.C. Perez-
˜
Flores, R. Reguillo-Carmona, A.M. Rodr´ıguez, E. Villasenor,
˜
Organometallics 25 (2006) 3698.
[4] A. Antinolo, F. Carrillo, M. Fajardo, S. Garcıa-Yuste, A. Otero, J.
˜
4.9. X-ray structure determinations for complexes
[Cp02Nb(CNXylyl)2][I3] and
[Cp02Nb(H)(P(OMe)3)] Æ (bzta)0-NH2. [(bzta)0-
NH2 = 2-amino-6-methylbenzothiazole] (15) and (14)
´
Organomet. Chem. 482 (1994) 93.
´
[5] A. Antinolo, F. Carrillo-Hermosilla, M. Fajardo, S. Garcıa-Yuste,
˜
M. Lafranchi, A. Otero, M.A. Pellinghelli, S. Prashar, E. Villasenor,
˜
Organometallics 15 (1996) 5507.
[6] F.A. Cotton, G. Wilkinson, C.A. Murillo, M. Bochmann, Advanced
Inorganic Chemistry, sixth ed., John Wiley and Sons, 1999, p. 247.
[7] (a) L. Breydo, H. Zang, K. Mitra, K.S. Gates, J. Am. Chem. Soc.
123 (2001) 2060;
Single crystals were mounted in inert oil in the cold gas
stream of the diffractometer. The X-ray diffraction data
were collected with a Nonius-Mach3 diffractometer with a
x-2h scan technique using graphite monochromated Mo
(b) N.L. Kelleher, C.L. Hendrickson, C.T. Walsh, Biochemistry 38
(1999) 15623;
(c) P.W. Baures, Org. Lett. 1 (1999) 249;
˚
Ka adiation (k = 0.71073 A). Data were corrected for Lor-
entz and polarization effects and absorption correction was
made for 14 (w scans) [25] but was not necessary for 15. The
structures were solved by direct methods using the SHELXS
computer program [26] completed by subsequent difference
Fourier synthesis and refined by full-matrix least-squares
procedures (SHELXL-97) [27] on F2. All the non-hydrogen
atoms were refined with anisotropic thermal parameters.
The hydrogen atoms were included in calculated positions
and refined ‘‘riding’’ on their parent carbon atoms except
H1, H2 and H3 for 14, which were found in the Fourier
map and refined freely. Relevant crystal and data parame-
ters are presented in Table 5. Crystals of 15 contained two
independent molecules per asymmetric unit cell.
(d) W.C. Groutas, R. Kuang, S. Ruan, J.B. Epp, R. Venkataraman,
T.M. Truong, Bioorg. Med. Chem. 6 (1998) 661.
[8] E.S. Raper, Coord. Chem. Rev. 61 (1985) 115;
E.S. Raper, Coord. Chem. Rev. 153 (1996) 199;
E.S. Raper, Coord. Chem. Rev. 165 (1997) 475.
[9] Selected references: (a) H. Fuhrmann, S. Brenner, P. Arndt, R.
Kempe, Inorg. Chem. 35 (1996) 6742;
(b) J.J.H. Edema, S. Gambarotta, A. Meetsma, A.L. Spek, N.
Veldman, Inorg. Chem. 30 (1991) 2062;
(c) A. Spannenberg, H. Fuhrmann, P. Arndt, W. Baumann, R.
Kempe, Angew. Chem., Int. Ed. 37 (1998) 3363;
(d) M. Tayebani, S. Gambarotta, G. Yap, Organometallics 17 (1998)
3639.
[10] R. Fandos, M. Lanfranchi, A. Otero, M.A. Pellinghelli, M.J. Ruiz,
P. Terreros, Organometallics 15 (1996) 4725.
[11] A. Antinolo, F. Carrillo-Hermosilla, A.E. Corrochano, J. Fernan-
˜
dez-Baeza, M. Lanfranchi, A. Otero, M.A. Pellinghelli, J. Organomet.
Chem. 577 (1999) 174.
Acknowledgements
[12] R. Fandos, M. Martinez-Ripoll, A. Otero, M.J. Ruiz, A. Rodriguez,
P. Terreros, Organometallics 17 (1998) 1465.
[13] A. Antinolo, F. Carrillo-Hermosilla, J. Fernandez-Baeza, A.M.
˜
We gratefully acknowledge financial support from the
´
´
´
Direccion General de Investigacion Cientıfica Spain
(MEC Grant No. CTQ2005-07918-C02-01/BQU) and the
Junta de Comunidades de Castilla-La Mancha (Grant
No. PAC-02-003, GC-02-010, PBI05-23 and PBI-05-029).
Fernandez de Toro, S. Garcia-Yuste, A. Otero, J.C. Perez-
Flores, A.M. Rodriguez, Inorg. Chim. Acta 300–302 (2000)
131.
´
[14] See for example A. Antinolo, S. Garcıa-Yuste, I. Lopez-Solera, A.
˜
Otero, J.C. Perez-Flores, I. del Hierro, L. Salvi, H. Cattey, Y.
Mugnier, J. Organomet. Chem. 690 (2005) 3134.
Appendix A. Supplementary material
[15] See for example E.V. Bakhmutova, V.I. Bakhmutov, N.V. Belkova,
´
M. Basora, L.M. Epstein, A. Lledos, G.I. Nikonov, E.S. Shubina,
CCDC 644685 and 644686 contain the supplementary
crystallographic data for 14 and 15. These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/
conts/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (+44) 1223-336-033; or e-mail: depos-
it@ccdc.cam.ac.uk. Supplementary data associated with
this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2007.03.038.
J. Tomas, E.V. Vorontsov, Chem. Eur. J. 10 (2004) 661.
[16] (a) A. Antinolo, F. Carrillo-Hermosilla, M. Freitas, S. Garcıa-Yuste,
´
˜
A. Otero, S. Prashar, E. Villasenor, M. Fajardo, Inorg. Chim. Acta
˜
259 (1997) 101;
´
(b) A. Antinolo, F. Carrillo-Hermosilla, M. Fajardo, S. Garcıa-
˜
Yuste, M. Lanfranchi, A. Otero, M.A. Pellinghelli, S. Prashar, E.
Villasenor, Organometallics 15 (1996) 5507.
˜
[17] V.W. Lin, S.L. Kuan, W.K. Leong, L.L. Koh, G.K. Tan, L.Y. Goh,
R.D. Webster, Inorg. Chem. 44 (2005) 5229–5240.
[18] A. Antinolo, F. Carrillo-Hermosilla, J. Fernandez-Baeza, S. Garcıa-
´
´
˜
´
Yuste, A. Otero, J. Sanchez-Prada, E. Villasenor, J. Organomet.
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