Diiron and diruthenium aminocarbyne complexes containing pseudohalides: Stereochemistry and reactivity

Article abstract of DOI:10.1016/j.ica.2004.11.033

Acetonitrile is easily displaced from [Fe₂{μ-CN(Me)(R)}(μ- CO)(CO)(MeCN)(Cp)₂][SO₃CF₃] (R = 2,6-Me ₂C₆H₃ (Xyl) (1a); Me (1b)) upon stirring in THF at room temperature in the presence of [NBu₄][SCN]. The resulting complexes trans-[Fe₂{μ-CN(Me)(R)}(μ-CO)(CO)(NCS)(Cp) ₂] (R = Xyl (trans-2a); Me (trans-2b)) are completely isomerised to cis-[Fe₂{μ-CN(Me)(R)}(μ-CO)(CO)(NCS)(Cp)₂] (R = Xyl (cis-2a); Me (cis-2b)) when heated at reflux temperature. Similarly, the complexes cis-[M₂{μ-CN(Me)(R)}(μ-CO)(CO)(NCO)(Cp)₂] (M = Fe, R = Me (4a); M = Ru, R = Xyl (4b); M = Ru, R = Me (4c)) and cis-[M ₂{μ-CN(Me)(R)}(μ-CO)(CO)(N₃)(Cp)₂] (M = Fe, R = Xyl (5a); M = Fe, R = Me (5b); M = Ru, R = Xyl (5c)) can be obtained by heating at reflux temperature a THF solution of [M₂{μ-CN(Me)(R)} (μ-CO)(CO)(MeCN)(Cp)₂][SO₃CF₃] (M = Fe, R = Xyl (1a); M = Fe, Me (1b); M = Ru, R = Xyl (1c); M = Ru, R = Me (1d)) in the presence of NaNCO and NaN₃, respectively. The reactions of 5 with MeO₂CCCCO₂Me, HCCCO₂Me and (NC)(H)CC(H)(CN) afford the triazolato complexes [M₂{μ-CN(Me)(R)}(μ-CO)(CO) {N₃C₂(CO₂Me)₂}(Cp)₂] (M = Fe, R = Xyl (6a); M = Fe, R = Me (6b); M = Ru, R = Xyl (6c)), [M ₂{μ-CN(Me)(R)}(μ- CO)(CO){N₃C₂(H)(CO ₂Me)}(Cp)₂] (M = Fe, R = Me (7a); M = Ru, R = Xyl (7b)) and [Fe₂{μ-CN(Me)(Xyl)}(μ-CO)(CO){N₃C ₂(H)(CN)}(Cp)₂] (8), respectively. The asymmetrically substituted triazolato complexes 7-8 are obtained as mixtures of N(1) and N(2) bonded isomers, whereas 6 exists only in the N(2) form. Methylation of 6-8 results in the formation of the triazole complexes [Fe₂{μ-CN(Me) (Xyl)}(μ-CO)(CO){N₃(Me)C₂(CO₂Me) ₂}(Cp)₂][CF₃SO₃] (9), [M ₂{μ-CN(Me)(R)}(μ-CO)(CO){N₃(Me)C₂(H) (CO₂Me)}(Cp)₂][CF₃SO₃] (M = Fe, R = Me (10a); M = Ru, R = Xyl (10b)) and [Fe₂{μ-CN(Me)(Xyl)}(μ-CO) (CO){N₃(Me)C₂(H)(CN)}(Cp)₂][CF ₃SO₃], 11. The crystal structures of trans-2b, 4b ? CH₂Cl₂, 5a, 6b ? 0.5CH₂Cl₂ and 8 ? CH₂Cl₂ have been determined.

Full text of DOI:10.1016/j.ica.2004.11.033

Inorganica Chimica Acta 358 (2005) 1204–1216
www.elsevier.com/locate/ica
Diiron and diruthenium aminocarbyne complexes containing
pseudohalides: stereochemistry and reactivity
*
Luigi Busetto , Fabio Marchetti, Stefano Zacchini, Valerio Zanotti
`
Dipartimento di Chimica Fisica ed Inorganica, Universita di Bologna, Viale Risorgimento 4, 40136 Bologna, Italy
Received 2 November 2004; accepted 24 November 2004
Available online 30 December 2004
Abstract
Acetonitrile is easily displaced from [Fe2{l-CN(Me)(R)}(l-CO)(CO)(MeCN)(Cp)2][SO3CF3] (R = 2,6-Me2C6H3 (Xyl) (1a);
Me (1b)) upon stirring in THF at room temperature in the presence of [NBu4][SCN]. The resulting complexes trans-
[Fe2{l-CN(Me)(R)}(l-CO)(CO)(NCS)(Cp)2] (R = Xyl (trans-2a); Me (trans-2b)) are completely isomerised to cis-[Fe2{l-
CN(Me)(R)}(l-CO)(CO)(NCS)(Cp)2] (R = Xyl (cis-2a); Me (cis-2b)) when heated at reflux temperature. Similarly, the complexes
cis-[M2{l-CN(Me)(R)}(l-CO)(CO)(NCO)(Cp)2] (M = Fe, R = Me (4a); M = Ru, R = Xyl (4b); M = Ru, R = Me (4c)) and cis-
[M2{l-CN(Me)(R)}(l-CO)(CO)(N3)(Cp)2] (M = Fe, R = Xyl (5a); M = Fe, R = Me (5b); M = Ru, R = Xyl (5c)) can be obtained
by heating at reflux temperature a THF solution of [M2{l-CN(Me)(R)}(l-CO)(CO)(MeCN)(Cp)2][SO3CF3] (M = Fe, R = Xyl
(1a); M = Fe, Me (1b); M = Ru, R = Xyl (1c); M = Ru, R = Me (1d)) in the presence of NaNCO and NaN3, respectively. The
reactions of 5 with MeO2CC„CCO2Me, HC„CCO2Me and (NC)(H)C@C(H)(CN) afford the triazolato complexes [M2{l-
CN(Me)(R)}(l-CO)(CO){N3C2(CO2Me)2}(Cp)2] (M = Fe, R = Xyl (6a); M = Fe, R = Me (6b); M = Ru, R = Xyl (6c)), [M2{l-
CN(Me)(R)}(l-CO)(CO){N3C2(H)(CO2Me)}(Cp)2] (M = Fe, R = Me (7a); M = Ru, R = Xyl (7b)) and [Fe2{l-CN(Me)
(Xyl)}(l-CO)(CO){N3C2(H)(CN)}(Cp)2] (8), respectively. The asymmetrically substituted triazolato complexes 7–8 are obtained
as mixtures of N(1) and N(2) bonded isomers, whereas 6 exists only in the N(2) form. Methylation of 6–8 results in the formation
of the triazole complexes [Fe2{l-CN(Me)(Xyl)}(l-CO)(CO){N3(Me)C2(CO2Me)2}(Cp)2][CF3SO3] (9), [M2{l-CN(Me)(R)}(l-
CO)(CO){N3(Me)C2(H)(CO2Me)}(Cp)2][CF3SO3] (M = Fe, R = Me (10a); M = Ru, R = Xyl (10b)) and [Fe2{l-CN(Me)
(Xyl)}(l-CO)(CO){N3(Me)C2(H)(CN)}(Cp)2][CF3SO3], 11. The crystal structures of trans-2b, 4bÆCH2Cl2, 5a, 6bÆ0.5CH2Cl2
and 8ÆCH2Cl2 have been determined.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Pseudohalides; Diiron complexes; Diruthenium complexes; Aminocarbyne; Triazolato complexes
1. Introduction
ꢀclass aꢁ and via sulfur or selenium to ꢀclass bꢁ metals
[3]. Conversely, in the case of isocyanates, NCOꢀ, coor-
dination usually occurs via nitrogen, being O-coordina-
tion quite rare [3c,4,5]. The coordinated pseudohalides
behave as 1,3-dipoles and, therefore, can be used in or-
der to prepare new ligands via 1,3-dipolar cycloaddition
reactions [6,7].
Herein, we report on the synthesis and reactivity of
diiron and diruthenium aminocarbyne complexes con-
taining terminal pseudohalides. This work is part of
our ongoing interest in the study of the formation of
new C–C and C–N bonds in bimetallic species [8–10],
Pseudohalides are quite versatile ligands, which can
coordinate to the metals both terminally or in a bridging
fashion [1,2]. Moreover, when the two end-atoms are
different, they can also display linkage isomerism. If
the atoms belong to different periods (e.g., NCSꢀ,
NCSeꢀ), they usually coordinate through nitrogen to
*
Corresponding author. Tel.: +39 051 2093694; fax: +39 051
2093690.
E-mail address: busetto@ms.fci.unibo.it (L. Busetto).
0020-1693/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2004.11.033

L. Busetto et al. / Inorganica Chimica Acta 358 (2005) 1204–1216
1205
with particular attention to the possibility of selectively
addressing the reactions on terminal or bridging ligands
and promoting their coupling.
(NCS) 2115 (vs); m(CO) 1969 (vs), 1809 (s); m(l-CN)
1
1568 (w) cmꢀ1. H NMR (CDCl3, 293 K): d 4.87, 4.58
(s, 10H, Cp), 4.71, 4.31 (s, 6H, NMe2). 13C{1H} NMR
(CDCl3, 293 K): d 340.6 (l-CN), 263.1 (l-CO), 211.7
(CO), 140.8 (NCS), 88.9, 87.4 (Cp), 52.5, 51.6 (NMe2).
2. Experimental
2.2. Synthesis of cis-[Fe2{l-CN(Me)(R)}(l-CO)(CO)
(NCS)(Cp)2] (R = Xyl (cis-2a); Me (cis-2b))
All reactions were carried out routinely under nitro-
gen using standard Schlenk techniques. Solvents were
distilled immediately before use under nitrogen from
appropriate drying agents. Infrared spectra were re-
corded on a Perkin–Elmer Spectrum 2000 FT-IR spec-
trophotometer and elemental analyses were performed
on a ThermoQuest Flash 1112 Series EA Instrument.
ESI MS spectra were recorded on a Waters Micromass
ZQ 4000 with samples dissolved in CH3CN. All NMR
measurements were performed on Varian Gemini 300
and Mercury Plus 400 instruments. The chemical shifts
A
solution of trans-[Fe2{l-CN(Me)(R)}(l-CO)
(CO)(NCS)(Cp)2] (0.120 mmol) in THF (10 ml) was
heated at reflux temperature for 5 h. The solvent was
then removed under reduced pressure and the residue
was chromatographed through alumina. The final prod-
uct cis-[Fe2{l-CN(Me)(R)}(l-CO)(CO)(NCS)(Cp)2]
was obtained using THF as eluent.
cis-2a: Yield, 56.0 mg (93%). Anal. Calc. for
C23H22Fe2N2O2S: C, 55.01; H, 4.42; N, 5.58. Found:
C, 55.32; H, 4.12; N, 5.76%. IR (CH2Cl2, 293 K): m
(NCS) 2112 (vs); m(CO) 1989 (vs), 1810 (s); m(l-CN)
1
for H and 13C were referenced to internal TMS. The
spectra were fully assigned via DEPT experiments and
1H,13C correlation measured using gs-HSQC and gs-
HMBC experiments [11]. NOE measurements were re-
corded using the DPFGSE-NOE sequence [12]. All
chemicals were used as received from Aldrich Co., ex-
1
1507 (w) cmꢀ1. H NMR (CDCl3, 293 K): d 7.42–7.25
(m, 3H, Me2C6H3), 4.79, 4.17 (s, 10H, Cp), 4.84 (s,
3H, NMe), 2.68, 2.27 (s, 6H, Me2C6H3). 13C{1H}
NMR (CDCl3, 293 K): d 341.4 (l-CN), 265.4 (l-CO),
211.5 (CO), 148.1 (Cipso Xyl), 140.7 (NCS), 135.3–
128.2 (C-Me + CH Xyl), 87.3, 86.2 (Cp), 53.9 (NMe),
18.5, 17.6 (Me2C6H3).
cept
[Fe2{l-CN(Me)(R)}(l-CO)(CO)(MeCN)(Cp)2]-
[SO3CF3] (R = 2,6-Me2C6H3 (Xyl) (1a); Me (1b)) and
[Ru2{l-CN(Me)(R)}(l-CO)(CO)(MeCN)(Cp)2][SO3CF3]
(R = Xyl (1c); Me (1d)) [9b] which were prepared by
published methods.
cis-2b: Yield, 39.6 mg (80%). Anal. Calc. for
C16H16Fe2N2O2S: C, 46.63; H, 3.91; N, 6.80. Found:
C, 46.87; H, 3.72; N, 6.98%. IR (CH2Cl2, 293 K):
m(NCS) 2112 (vs); m(CO) 1987 (vs), 1809 (s); m(l-CN)
2.1. Synthesis of trans-[Fe2{l-CN(Me)(R)}(l-
CO)(CO)(NCS)(Cp)2] (R = Xyl (trans-2a); Me,
(trans-2b))
1
1579 (w) cmꢀ1. H NMR (CDCl3, 293 K): d 4.74, 4.62
(s, 10H, Cp), 4.44, 4.13 (s, 6H, NMe2).
[NBu4][SCN] (129 mg, 0.430 mmol) was added to a
CH2Cl2(6 ml) solution of [Fe2{l-CN(Me)(R)}(l-CO)
(CO)(NCMe)(Cp)2][CF3SO3] (0.147 mmol) and the mix-
ture was stirred at room temperature for 3 h. The
solvent was then removed under reduced pressure and
the residue was chromatographed through alumina. A
fraction containing trans-[Fe2{l-CN(Me)(R)}(l-CO)
(CO)(NCS)(Cp)2] was obtained using CH2Cl2 as eluent.
trans-2a: Yield, 52.4 mg (71%). Anal. Calc. for
C23H22Fe2N2O2S: C, 55.01; H, 4.42; N, 5.58. Found:
C, 55.32; H, 4.12; N, 5.76%. IR (CH2Cl2, 293 K): m
(NCS) 2112 (vs); m(CO) 1968 (vs), 1812 (s); m(l-CN)
2.3. Synthesis of cis-[Fe2{l-CN(Me)(Xyl)}(l-CO)
(CO)(NCSMe)(Cp)2][CF3SO3] (3)
A
solution of cis-[Fe2{l-CN(Me)(Xyl)}(l-CO)
(CO)(NCS)(Cp)2] (131 mg, 0.260 mmol) in CH2Cl2 (8
ml) was treated with CF3SO3Me (0.030 ml, 0.26 mmol)
and the solution was stirred for 30 min at room temper-
ature. Then, the mixture was filtered on a celite pad and
the solvent was removed under reduced pressure. The
residue was washed with diethyl ether (2 · 10 ml), yield-
ing a brown powder.
cis-3: Yield, 150.0 mg (87%). Anal. Calc. for
C25H25F3Fe2N2O5S2: C, 45.07; H, 3.78; N, 4.20. Found:
C, 45.15; H, 3.81; N, 4.10%. IR (CH2Cl2, 293 K): m(CO)
1
1549 (w) cmꢀ1. H NMR (CDCl3, 293 K): d 7.42–7.29
(m, 3H, Me2C6H3), 4.93 (s, 3H, NMe), 4.76, 4.38 (s,
10H, Cp), 2.57, 2.41 (s, 6H, Me2C6H3). 13C {1H}
NMR (CDCl3, 293 K): d 345.5 (l-CN), 262.6 (l-CO),
212.5 (CO), 148.7 (Cipso Xyl), 140.6 (NCS), 134.0,
132.4 (C-Me Xyl), 129.5, 129.3, 128.5 (CH Xyl), 88.9,
87.7 (Cp), 53.6 (NMe), 18.7, 18.4 (Me2C6H3).
trans-2b: Yield, 46.0 mg (76%). Anal. Calc. for
C16H16Fe2N2O2S: C, 46.63; H, 3.91; N, 6.80. Found:
C, 46.87; H, 3.72; N, 6.98%. IR (CH2Cl2, 293 K): m
1
1989 (vs), 1810 (s); m(l-CN) 1507 (w) cmꢀ1. H NMR
(CDCl3, 293 K) Isomer a: d 7.42–7.29 (m, 3H,
Me2C6H3), 5.04, 4.51 (s, 10H, Cp), 4.79 (s, 3H, NMe),
2.70, 2.13 (s, 6H, Me2C6H3), 2.42 (s, 3H, SMe); Isomer
b: d 7.42–7.29 (m, 3H, Me2C6H3), 5.17, 4.34 (s, 10H,
Cp), 4.50 (s, 3H, NMe), 2.71, 2.07 (s, 6H, Me2C6H3),
2.35 (s, 3H, SMe). Isomer ratio = 2. 13C{1H} NMR
(CDCl3, 293 K) Isomer a: d 337.2 (l-C), 263.4 (l-CO),

1206
L. Busetto et al. / Inorganica Chimica Acta 358 (2005) 1204–1216
210.9 (CO), 147.9 (Cipso Xyl), 133.1, 132.0, 129.9,
129.1, 128.9 (C-Me + CH Xyl), 124.1 (NCS), 88.1, 87.7
(Cp), 54.2 (NMe), 18.7, 17.4 (Me2C6H3), 16.7 (SMe);
Isomer b: 336.5 (l-C), 264.1 (l-CO), 210.4 (CO), 148.0
(Cipso Xyl), 133.5, 132.4, 129.8, 129.0 (C-Me + CH
Xyl), 123.7 (NCS), 89.1, 86.8 (Cp), 55.2 (NMe), 18.9,
17.8, (Me2C6H3), 16.6 (SMe). ESI-MS (ES+): 517 (M+,
65%), 444 (M+ ꢀ NCSMe, 100%) m/z.
sion was heated at reflux temperature for 3 h. Hence,
the solvent was removed in vacuo and the residue dis-
solved in CH2Cl2 and chromatographed through
Al2O3.
The
product
[M2{l-CN(Me)(R)}(l-CO)
(CO)(N3)(Cp)2] was obtained using THF as eluent.
5a: Yield, 78.7 mg (70%). Anal. Calc. for C22H22Fe2-
N4O2: C, 54.36; H, 4.56; N, 11.52. Found: C, 54.57; H,
4.01; N, 11.23%. IR (CH2Cl2, 293 K): m(N3) 2033 (vs);
1
m(CO) 1980 (s), 1800 (br) cmꢀ1. H NMR (CDCl3, 293
2.4. Synthesis of [M2{l-CN(Me)(R)}(l-CO)
(CO)(NCO)(Cp)2] (M = Fe, R = Me (4a); M = Ru
R = Xyl (4b); M = Ru, R = Me (4c))
K) Isomer a: d 7.40–7.26 (m, 3H, Me2C6H3), 4.87 (s,
3H, NMe), 4.80, 4.30 (s, 10H, Cp), 2.71, 2.23 (s, 6H,
Me2C6H3); Isomer b: d 7.40–7.26 (m, 3H, Me2C6H3),
5.04 (s, 3H, NMe), 4.85, 4.21 (s, 10H, Cp), 2.61, 2.42
(s, 6H, Me2C6H3). a/b = 10. 13C{1H} NMR (CDCl3,
293 K) Isomer a: d 342.5 (l-CN), 266.1 (l-C O), 211.3
(CO), 148.4–128.5 (Xyl), 86.6 (Cp), 52.3 (NMe), 18.6,
17.6 (Me2C6H3); Isomer b: 86.5 (Cp), 52.4 (NMe).
5b: Yield, 59.2 mg (65%). Anal. Calc. for C15H16Fe2-
N4O2: C, 45.49; H, 4.07; N, 14.15. Found: C, 45.11; H,
4.23; N, 14.45%. IR (CH2Cl2, 293 K): m(N3) 2030 (vs);
NaNCO (500 mg, 7.69 mmol) was added to a solu-
tion of [M2{CN(Me)(R)}(l-CO)(CO)(CH3CN)(Cp)2]-
[TfO] (0.230 mmol) in THF (15 ml) and the resulting
suspension was heated at reflux temperature for 3 h.
Hence, the solvent was removed in vacuo and the resi-
due dissolved in CH2Cl2 and chromatographed through
Al2O3. A fraction corresponding to the final product
[M2{l-CN(Me)(R)}(l-CO)(CO)(NCO)(Cp)2] was ob-
tained using MeCN as eluent.
4a: Yield, 69.2 mg (76%). Anal. Calc. for C16H16Fe2-
N2O3: C, 48.52; H, 4.07; N, 7.08. Found: C, 48.23; H,
4.21; N, 6.89%. IR (CH2Cl2, 293 K): m(NCO) 2237
(vs); m(CO) 1980 (vs), 1803 (m) cmꢀ1. 1H NMR (CDCl3,
293 K): d 4.77, 4.63 (s, 10H, Cp), 4.64, 4.23 (s, 6H,
NMe2).
1
m(CO) 1976 (vs), 1806 (s); m(l-CN) 1578 (m) cmꢀ1. H
NMR (CDCl3, 293 K): d 4.74, 4.63 (s, 10H, Cp), 4.66,
4.24 (s, 6H, NMe2). 13C{1H} NMR (CDCl3, 293 K): d
89.1, 86.6 (Cp), 52.8, 51.6 (NMe2).
5c: Yield, 99.5 mg (75%). Anal. Calc. for
C22H22N4O2Ru2: C, 45.83; H, 3.85; N, 9.72. Found: C,
46.15; H, 3.61; N, 9.91%. IR (CH2Cl2, 293 K): m(N3)
2033 (vs); m(CO) 1974 (s), 1800 (s); m(l-CN) 1512 (m)
1
4b: Yield, 104.7 mg (79%). Anal. Calc. for
C23H22N2O3Ru2: C, 47.91; H, 3.85; N, 4.86. Found: C,
47.46; H, 3.99; N, 4.65%. IR (CH2Cl2, 293 K):
m(NCO) 2236 (s); m(CO) 1978 (vs), 1802 (s); m(l-CN)
cmꢀ1. H NMR (CDCl3, 293 K): d 7.29–7.20 (m, 3H,
Me2C6H3), 5.21, 4.83 (s, 10H, Cp), 4.30 (s, 3H, NMe),
2.39, 2.32 (s, 6H, Me2C6H3). 13C{1H} NMR (CDCl3,
293 K): d 312.1 (l-CN), 237.0 (l-CO), 200.3 (CO),
147.9 (Cipso Xyl), 133.7, 132.6 (C-Me Xyl), 129.7,
128.3, 128.0 (CH Xyl), 88.5, 87.8 (Cp), 51.3 (NMe),
18.2, 17.5 (Me2C6H3).
1
1519 (m) cmꢀ1. H NMR (CDCl3, 293 K): d 7.29–7.19
(m, 3H, Me2C6H3), 5.16, 4.84 (s, 10H, Cp), 4.25 (s,
3H, NMe), 2.40, 2.29 (s, 6H, Me2C6H3). 13C{1H}
NMR (CDCl3, 293 K): d 313.1 (l-CN), 235.8 (l-CO),
200.1 (CO), 147.9 (Cipso Xyl), 133.7, 132.6 (C-Me
Xyl), 129.9, 128.4, 128.1 (CH Xyl), 128.9 (NCO), 88.5,
87.5 (Cp), 51.5 (NMe), 18.3, 17.5 (Me2C6H3).
2.6. Synthesis of [M2{l-CN(Me)(R)}(l-CO)(CO)
{N3C2(CO2Me)2}(Cp)2] (M = Fe, R = Xyl (6a);
M = Fe R = Me (6b); M = Ru, R = Xyl (6c))
4c: Yield, 92.7 mg (83%). Anal. Calc. for
C16H16N2O3Ru2: C, 39.51; H, 3.32; N, 5.76. Found: C,
39.89; H, 3.68; N, 5.91%. IR (CH2Cl2, 293 K):
m(NCO) 2237 (s); m(CO) 1977 (vs), 1802 (s); m(l-CN)
A
solution containing [M2{l-CN(Me)(R)}(l-
CO)(CO)(N3)(Cp)2] (0.411 mmol) and MeO2CC„
CCO2Me (0.2 ml, 1.63 mmol) in THF (15 ml) was
heated at reflux temperature for 3 h and then the solvent
was removed under reduced pressure. Hence, the residue
was washed with petroleum ether (2 · 20 ml), dissolved
in CH2Cl2 and chromatographed through Al2O3. The fi-
nal product was obtained as an orange-brown fraction
using THF as eluent.
1
1589 (m), 1564 (ms) cmꢀ1. H NMR (CDCl3, 293 K):
d 5.20, 5.02 (s, 10H, Cp), 4.02, 3.98 (s, 6H, NMe2).
13C{1H} NMR (CDCl3, 293 K): d 307.0 (l-CN), 236.2
(l-CO), 199.3 (CO), 127.2 (NCO), 88.5, 87.1 (Cp),
52.4, 51.1 (NMe2).
2.5. Synthesis of [M2{l-CN(Me)(R)}(l-CO)(CO)(N3)
(Cp)2] (M = Fe, R = Xyl (5a); M = Fe R = Me (5b);
M = Ru, R = Xyl (5c))
6a: Yield, 206.6 mg (70%). Anal. Calc. for C28H28Fe2-
N4O6: C, 53.53; H, 4.49; N, 8.92. Found: C, 53.89; H,
4.06; N, 8.68%. IR (CH2Cl2, 293 K): m (CO) 1985 (vs),
1806 (s); m(CO2Me) 1734 (s); m(l-CN) 1507 (m) cmꢀ1
.
NaN3 (500 mg, 7.69 mmol) was added to a solution
of [M2{CN(Me)(R)}(l-CO)(CO)(CH3CN)(Cp)2][TfO]
(0.230 mmol) in THF (15 ml) and the resulting suspen-
1H NMR (CDCl3, 293 K): d 7.31–7.23 (m, 3H,
Me2C6H3), 4.96 (s, 3H, NMe), 4.85, 4.28 (s, 10H, Cp),
3.72 (s, 6H, CO2Me), 2.68, 2.15 (s, 6H, Me2C6H3).

L. Busetto et al. / Inorganica Chimica Acta 358 (2005) 1204–1216
1207
13C{1H} NMR (CDCl3, 293 K): d 340.4 (l-CN), 265.9
(l-CO), 210.6 (CO), 162.1 (C O2Me), 148.9 (Cipso
Xyl), 140.5 (N3C2), 134.8, 132.6 (C-Me Xyl), 130.2,
128.3, 128.1 (CH Xyl), 87.3, 86.9 (Cp), 53.2 (NMe),
51.5 (CO2Me), 18.6, 17.1 (Me2C6H3).
O2Me), 139.7 (N3CHC CO2Me), 139.4 (CH), 87.1,
86.7 (Cp), 53.5, 52.8 (NMe2), 50.9 (CO2Me).
7b: Yield, 128.7 mg (81%). Anal. Calc. for
C26H26N4O4Ru2: C, 47.27; H, 3.97; N, 8.48. Found: C,
47.65; H, 3.68; N, 8.89%. IR (CH2Cl2, 293 K): m (CO)
1978 (s), 1803 (s); m(CO2Me) 1712 (s); m(l-CN) 1520
6b: Yield, 168.1 mg (76%). Anal. Calc. for C21H22Fe2-
N4O6: C, 46.87; H, 4.12; N, 10.41. Found: C, 47.05; H,
3.98; N, 10.07%. IR (CH2Cl2, 293 K): m(CO) 1983 (vs),
1806 (s); m(CO2Me) 1727 (s); m(l-CN) 1577 (w), 1551
1
(ms), 1505 (w) cmꢀ1. H NMR (CDCl3, 293 K) Major
isomer: d 7.86 (s, 1H, CH), 7.27–7.22 (m, 3H,
Me2C6H3), 5.25, 4.86 (s, 10H, Cp), 4.52 (s, 3H, NMe),
3.83 (s, 3H, CO2Me), 2.46, 2.18 (s, 6H, Me 2C6H3); Min-
or isomer: d 7.79 (s, 1H, CH), 7.27–7.22 (m, 3H,
Me2C6H3), 5.33, 4.86 (s, 10H, Cp), 4.48 (s, 3H, NMe),
3.79 (s, 3H, CO2Me), 2.46, 2.19 (s, 6H, Me2C6H3). Ma-
jor/Minor = 2. 13C{1H} NMR(CDCl3, 293 K) Major
isomer: d 310.7 (l-C N), 240.1 (l-CO), 199.1 (CO),
162.9 (C O2Me), 148.5 (Cipso Xyl), 139.5 (CH), 137.3
(N3CHCCO2Me), 134.5, 132.3 (C-Me Xyl), 130.0–
127.8 (CH Xyl), 88.7, 88.0 (Cp), 52.5 (NMe), 51.0
(CO2Me), 18.3, 17.3 (Me2C6H3); Minor isomer: d
311.9 (l-CN), 237.3 (l-CO), 199.5 (CO), 162.8
(CO2Me), 148.5 (Cipso Xyl), 139.4 (CH), 138.1
(N3CHC CO2Me), 134.5, 132.5 (C-Me Xyl), 130.0–
127.8 (CH Xyl), 88.6, 88.2 (Cp), 52.0 (NMe), 51.0
(CO2Me), 18.3, 16.9 (Me2C6H3).
1
(m) cmꢀ1. H NMR (CDCl3, 293 K): d 4.73, 4.71 (s,
10H, Cp), 4.68, 4.11 (s, 6H, NMe 2), 3.69 (s, 6H,
CO2Me). 13C{1H} NMR (CDCl3, 293 K): d 334.3 (l-
CN), 265.9 (l-CO), 210.0 (CO), 162.1 (C O2Me), 140.2
(N3C2), 87.0, 86.9 (Cp), 53.3, 52.2 (NMe2), 51.6
(CO2Me).
6c: Yield, 254.4 mg (86%). Anal. Calc. for
C28H28N4O6Ru2: C, 46.79; H, 3.93; N, 7.80. Found: C,
46.24; H, 4.11; N, 7.99%. IR (CH2Cl2, 293 K): m (CO)
1979 (vs), 1804 (s); m(CO2Me) 1738 (sh), 1713 (vs); m(l-
CN) 1519 (m) cmꢀ1 1H NMR (CDCl3, 293 K): d
.
7.31–7.20 (m, 3H, Me2C6H3), 5.33, 4.85 (s, 10H, Cp),
4.44 (s, 3H, NMe), 3.83 (s, 6H, CO2Me), 2.44, 2.22 (s,
6H, Me2C6H3). 13C{1H} NMR (CDCl3, 293 K): d
311.4 (l-CN), 236.3 (l-CO), 199.0 (CO), 162.2 (C
O2Me), 148.3 (Cipso Xyl), 139.7 (N3C2), 134.3, 132.3
(C-Me Xyl), 129.9, 128.2, 127.7 (CH Xyl), 88.6,
88.1 (Cp), 52.1 (NMe), 51.6 (CO2Me), 18.4, 17.1
(Me2C6H3).
2.8. Synthesis of [Fe2{l-CN(Me)(Xyl)}(l-CO)(CO)
{N3C2(H)(CN)}(Cp)2] (8)
A solution containing [Fe2{l-CN(Me)(Xyl)}(l-CO)
(CO)(N3)(Cp)2] (75.1 mg, 0.154 mmol) and (NC)(H)C@
C(H)(CN) (34.1 mg, 0.437 mmol) in THF (6 ml) was
heated at reflux temperature for 5 h and then the solvent
was removed under reduced pressure. Hence, the residue
was washed with petroleum ether (2 · 20 ml), dissolved
in CH2Cl2 and chromatographed through Al2O3. The fi-
nal product was obtained as an orange-brown fraction
using THF as eluent.
8: Yield, 67.8 mg (82%). Anal. Calc. for C25H23Fe2-
N5O2: C, 55.90; H, 4.32; N, 13.04. Found: C, 55.59;
H, 4.54; N, 13.15%. IR (CH2Cl2, 293 K): m(CN) 2232
(ms); m(CO) 1986 (vs), 1805 (s); m(l-CN) 1509 (ms),
1505 (w) cmꢀ1. 1H NMR (CDCl3, 293 K) Major isomer:
d 7.74 (s, 1H, CH), 7.31–7.21 (m, 3H, Me2C6H3), 5.11 (s,
3H, NMe), 4.74, 4.29 (s, 10H, Cp), 2.69, 2.03 (s, 6H,
Me2C6H3); Minor isomer: d 7.46 (s, 1H, CH), 7.31–
7.21 (m, 3H, Me2C6H3), 4.96 (s, 3H, NMe), 4.81, 4.28
(s, 10H, Cp), 2.68, 2.08 (s, 6H, Me2C6H3). Major/Min-
or = 1.1. 13C{1H} NMR (CDCl3, 293 K) Major
isomer: d 339.2 (l-CN), 270.9 (l-CO), 210.1 (CO),
148.9 (Cipso Xyl), 140.9 (CH), 134.5, 132.4 (C-Me
Xyl), 130.4–128.2 (CH Xyl), 118.5 (CN), 114.4
(N3CHCCN), 87.2, 86.9 (Cp), 53.9 (NMe), 18.6, 17.2
(Me2C6H3); Minor isomer: d 340.9 (l-CN), 266.7 (l-
CO), 210.8 (CO), 149.0 (Cipso Xyl), 139.2 (CH),
134.5, 132.6 (C-Me Xyl), 130.4–128.2 (CH Xyl), 119.4
2.7. Synthesis of [M2{l-CN(Me)(R)}(l-CO)(CO)
{N3C2(H)(CO2Me)}(Cp)2] (M = Fe, R = Me (7a);
M = Ru, R= Xyl (7b))
A
solution containing [M2{l-CN(Me)(R)}(lCO)
(CO)(N3)(Cp)2] (0.240 mmol) and HC„CCO2Me (0.1
ml, 1.12 mmol) in THF (15 ml) was heated at reflux tem-
perature for 3 h and then the solvent was removed under
reduced pressure. Hence, the residue was washed with
petroleum ether (2 · 20 ml), dissolved in CH2Cl2 and
chromatographed through Al2O3. The final product
was obtained as an orange-brown fraction using THF
as eluent.
7a: Yield, 93.5 mg (81%). Anal. Calc. for C19H20Fe2-
N4O4: C, 47.53; H, 4.20; N, 11.67. Found: C, 47.86; H,
4.01; N, 11.12%. IR (CH2Cl2, 293 K): m(CO) 1982 (vs),
1805 (s); m(CO2Me) 1721 (s); m(l-CN) 1576 (ms), 1505
1
(w) cmꢀ1. H NMR (CDCl3, 293 K) Major isomer: d
7.56 (s, 1H, CH), 4.82, 4.78 (s, 10H, Cp), 4.70, 4.21 (s,
6H, NMe2), 3.73 (s, 3H, CO2Me); Minor isomer: d
7.72 (s, 1H, CH), 4.91, 4.81 (s, 10H, Cp), 4.70, 4.21 (s,
6H, NMe2), 3.76 (s, 3H, CO2Me). Major/Minor = 2.
13C{1H} NMR (CDCl3, 293 K) Major isomer: d 334.3
(l-CN), 266.6 (l-CO), 210.3 (CO), 162.4 (CO2Me),
138.2 (N3CHCCO2Me), 137.6 (CH), 87.0, 86.9 (Cp),
53.2, 52.2 (NMe2), 50.8 (CO2Me); Minor isomer: d
332.5 (l-C N), 270.7 (l-CO), 209.6 (CO), 162.2 (C

1208
L. Busetto et al. / Inorganica Chimica Acta 358 (2005) 1204–1216
(CN), 114.5 (N3CHCCN), 87.3, 86.0 (Cp), 53.1 (NMe),
18.6, 16.9 (Me2C6H3).
2.11. Synthesis of [Fe2{l-CN(Me)(Xyl)}
(l-CO)(CO){N3(Me)C2(H)(CN)}(Cp)2][CF3SO3]
(11)
2.9. Synthesis of [Fe2{l-CN(Me)(Xyl)}(l-CO)(CO)
{N3(Me)C2(CO2Me)2}(Cp)2][CF3SO3] (9)
CF3SO3Me (0.1 ml, 0.884 mmol) was added to a solu-
tion of 8 (190.0 mg, 0.354 mmol) in CH2Cl2 (6 ml); after
stirring at room temperature for 30 min, the solvent was
removed under reduced pressure and the residue washed
with Et2O (2 · 10 ml).
CF3SO3Me (0.1 ml, 0.884 mmol) was added to a solu-
tion of 6a (200.0 mg, 0.279 mmol) in CH2Cl2 (6 ml);
after stirring at room temperature for 30 min, the sol-
vent was removed under reduced pressure and the resi-
due washed with Et2O (2 · 10 ml).
11: Yield, 223.5 mg (92%). Anal. Calc. for
C27H26F3Fe2N5O5S: C, 47.26; H, 3.82; N, 10.21. Found:
C, 47.62; H, 3.67; N, 10.45%. IR (CH2Cl2, 293 K):
m(CN) 2220 (m), m(CO) 1986 (vs), 1818 (s); m(l-CN)
1522 (m) cmꢀ1. 1H NMR (CDCl3, 293 K) Major isomer:
d 9.13 (s, 1H, CH), 7.30 (m, 3H, Me2C6H3), 4.19 (s, 3H,
NMe), 5.07, 4.50 (s, 10H, Cp), 3.85 (s, 3H, N3Me), 2.69,
2.03 (s, 6H, Me2C6H3); Minor isomer: d 8.37 (s, 1H,
CH), 7.30 (m, 3H, Me2C6H3), 5.14 (s, 3H, NMe), 4.98,
4.38 (s, 10H, Cp), 4.34 (s, 3H, N3Me), 2.66, 2.11 (s,
6H, Me2C6H3). Major/Minor = 1.2. 13C{1H} NMR
(CDCl3, 293 K) Major isomer: d 336.1 (l-C N), 265.6
(l-CO), 210.7 (CO), 148.3 (Cipso Xyl), 134.8, 132.6
(C-Me Xyl), 132.3 (N3CHC CN), 130.1–128.8 (CH
Xyl), 118.7 (CH), 117.7 (CN), 88.2, 86.8 (Cp), 54.2
(NMe), 41.0 (N3Me), 18.3, 17.0 (Me2C6H3); Minor iso-
mer: d 338.3 (l-CN), 261.7 (l-CO), 210.7 (C O), 147.7
(Cipso Xyl), 136.7, 132.8 (C-Me Xyl), 131.8
(N3CHCCN), 130.1–128.8 (CH Xyl), 119.2 (CH),
116.8 (CN), 88.3, 88.2 (Cp), 54.0 (NMe), 40.3 (N3Me),
18.5, 16.9 (Me2C6H3).
9: Yield, 222.6 mg (92%). Anal. Calc. for
C30H31F3Fe2N4O9S: C, 41.55; H, 3.60; N, 6.46. Found:
C, 41.92; H, 3.47; N, 6.31%. IR (CH2Cl2, 293 K): m(CO)
1
1982 (vs), 1808 (s); m(CO2Me) 1745 (s) cmꢀ1. H NMR
(CDCl3, 293 K): d 7.25 (m, 3H, Me2C6H3), 5.06 (s,
3H, NMe), 4.90, 4.28 (s, 10H, Cp), 3.98 (s, 3H,
N3Me), 3.80 (s, 6H, CO2Me), 2.62, 2.15 (s, 6H,
Me2C6H3). 13C{1H} NMR (CDCl3, 293 K): d 330.4
(l-CN), 266.9 (l-CO), 210.7 (CO), 155.8 (C O2Me),
148.9 (Cipso Xyl), 133.6, 132.8, 132.7 (C-Me
Xyl + N3C2), 130.0, 128.8, 128.7 (CH Xyl), 88.3, 87.2
(Cp), 54.6, 53.7 (NMe + CO2Me), 39.5 (N3Me), 18.7,
16.9 (Me2C6H3).
2.10. Synthesis of [M2{l-CN(Me)(R)}(l-CO)(CO)
{N3(Me)C2(H)(CO2Me)}(Cp)2][CF3SO3] (M = Fe,
R = Me (10a); M = Ru, R = Xyl (10b))
CF3SO3Me (0.1 ml, 0.884 mmol) was added to a solu-
tion of 7 (0.300 mmol) in CH2Cl2 (6 ml); after stirring at
room temperature for 30 min, the solvent was removed
under reduced pressure and the residue washed with
Et2O (2 · 10 ml).
2.12. Crystallography
Compounds trans-2b, 4bÆCH2Cl2, 5a, 6bÆ0.5CH2Cl2
and 8ÆCH2Cl2 were crystallised from CH2Cl2/petroleum
ether at ꢀ20ꢁC. Crystal data were collected on a Bruker
AXS SMART 2000 CCD diffractometer using Mo Ka
radiation. Intensity data were measured over full diffrac-
tion spheres using 0.3ꢁ wide x scans, crystal-to-detector
distance 5.2 cm. Cell dimensions and orientation ma-
trixes were initially determined from least-squares
refinements on reflections measured in 3 sets of 20 expo-
sures collected in three different x regions and eventu-
ally refined against all reflections. The software SMART
[13] was used for collecting frames of data, indexing
reflections and determinations of lattice parameters.
The collected frames were then processed for integration
by the software SAINT and empirical absorption correc-
tions were applied with SADABS [14]. The structure was
solved by direct methods and refined by full-matrix
least-squares based on all data using F2 [15]. Crystal
data are listed in Table 1. Non-H atoms were refined
anisotropically, unless otherwise stated. H-atoms were
placed in calculated positions and treated isotropically
using the 1.2-fold Uiso value of the parent atom except
methyl protons, which were assigned the 1.5-fold Uiso
10a: Yield, 172.0 mg (89%). Anal. Calc. for
C21H23F3Fe2N4O7S: C, 39.15; H, 3.60; N, 8.70. Found:
C, 39.03; H, 3.82; N, 8.46%. IR (CH2Cl2, 293 K): m(CO)
1983 (vs), 1799 (s); m(CO2Me) 1742 (m), 1718 (m);
m(l-CN) 1581 (m) cmꢀ1 1H NMR (CDCl3, 293 K):
.
d 8.03 (s, 1H, CH), 4.96, 4.79 (s, 10H, Cp), 4.82, 4.30
(s, 6H, NMe2), 4.03 (s, 3H, N3Me), 3.84 (s, 3H,
CO2Me).
10b: Yield, 235.0 mg (95%). Anal. Calc. for
C28H29F3N4O7Ru2S: C, 40.78; H, 3.54; N, 6.80. Found:
C, 40.46; H, 3.74; N, 7.01%. IR (CH2Cl2, 293 K): m(CO)
1978 (vs), 1806 (s); m(CO2Me) 1746 (s); m(l-CN) 1528
1
(ms) cmꢀ1. H NMR (CDCl3, 293 K): d 8.14 (s, 1H,
CH), 7.24–7.21 (m, 3H, Me2C6H3), 5.34, 4.89 (s, 10H,
Cp), 4.36 (s, 3H, NMe), 4.19 (s, 3H, N3Me), 3.90 (s,
3H, CO2Me), 2.41, 2.19 (s, 6H, Me2C6H3). 13C{1H}
NMR (CDCl3, 293 K): d 310.8 (l-CN), 240.0 (l-CO),
200.3 (CO), 156.9 (C O2Me), 148.2 (Cipso Xyl), 143.5
(CH), 130.0, 132.6 (C-Me Xyl), 129.9 (N3CHC CO2Me),
129.8, 128.8, 128.7 (CH Xyl), 89.6, 88.3 (Cp), 53.3
(NMe), 53.1 (CO2Me), 38.7 (N3Me), 18.4, 16.9
(Me2C6H3).

L. Busetto et al. / Inorganica Chimica Acta 358 (2005) 1204–1216
1209
value of the parent C-atoms. One Cp ligand in trans-3b
and the CH2Cl2 molecule in 4bÆCH2Cl2 are disordered.
Disordered atomic positions were split and refined iso-
tropically using similar distance and similar U restraints
and one occupancy parameter per disordered group.
l-iminium ligand. The Fe(1)–N(2) interaction [1.932(3)
A] indicates a p-contribution to the bond; in agreement
˚
with this, the Fe(1)–N(2)–C(16)–S(1) unit is almost
linear [bond angles Fe(1)–N(2)–C(16) 169.7(3) and
N(2)–C(16)–S(1) 178.4(4)ꢁ ] and N(2) and C(16) exhibit
an almost perfect sp hybridisation. This linear arrange-
ment of the atoms perfectly agrees with a N-coordinated
NCSꢀ ligand [16]. Interestingly, the mononuclear com-
plex [Fe(Cp)(CO)2(NCS)] exists in both the N- and S-
bonded isomeric forms [17], where the N-bonded isomer
is thermodynamically more stable. The NMR data for
trans-2a,b show the presence of only one species in solu-
tion, indicating the complete absence of linkage
isomerism.
3. Results and discussion
The MeCN ligand in the l-aminocarbyne complexes
[Fe2{l-CN(Me)(R)}(l-CO)(CO)(MeCN)(Cp)2][SO3CF3]
(R = Xyl (1a); Me (1b)) is almost quantitatively replaced
by NCSꢀ after stirring 1 in THF for 3 h in the presence
of an excess of [NBu4][SCN] (Scheme 1). The new com-
plexes
trans-[Fe2{l-CN(Me)(R)}(l-CO)(CO)(NCS)
Complexes trans-2a,b are completely converted into
cis-[Fe2{l-CN(Me)(R)}(l-CO)(CO)(NCS)(Cp)2] (R =
Xyl (cis-2a); Me (cis-2b)) after heating at reflux temper-
ature in THF solution for 5 h (Scheme 1). The isomeri-
sation is clearly indicated by a shift of ca. 20 cmꢀ1
toward higher frequencies of the terminal m(CO),
whereas the other IR bands remain nearly unchanged.
Also, the NMR data for trans-2 and cis-2 are very sim-
ilar as expected, since they differ only for the relative po-
sition of the Cp ligands. The different arrangement of
the Cp has been further supported by NOE studies;
thus, NOE is mutually generated between the two Cp li-
gands in cis-2 but not in trans-2. Complexes cis-2 can be
directly obtained from 1 by heating at reflux the latter in
the presence of NCSꢀ.
(Cp)2] (R = Xyl (trans-2a); Me (trans-2b)) are, hence,
obtained in good yields (71–76%) after column chroma-
tography, and they have been fully characterised by IR
and NMR spectroscopy.
The molecular structure of trans-2b has also been
determined by X–ray crystallography (Fig. 1 and Table
2). The Cp ligands adopt a trans geometry relative to the
mean plane determined by the Fe2(l-C)2 core. This is
quite unusual, since most of the structures reported for
diiron complexes containing a bridging aminocarbyne li-
gand show a cis geometry of the Cp ligands [8–10]. The
˚
C(13)–N(1) interaction [1.297(5) A] exhibits a consider-
ably double bond character, suggesting that the l-amin-
ocarbyne ligand can be alternatively described as a
Table 1
Crystal data and experimental details
Complex
trans-2b
4bÆCH2Cl2
5a
6bÆ0.5CH2Cl2
8ÆCH2Cl2
Formula
Fw
C16H16Fe2N2O2S C24H24Cl2N2O3Ru2 C22H22Fe2N4O2
C21.5H23ClFe2N4O6 C26H25Cl2Fe2N5O2
412.07
293(2)
0.71073
orthorhombic
Pbca
661.49
293(2)
0.71073
monoclinic
P21/n
486.14
293(2)
580.59
293(2)
0.71073
622.11
100(2)
T (K)
˚
k (A)
0.71073
monoclinic
P21/c
0.71073
monoclinic
P21/n
Crystal system
Space group
triclinic
ꢀ
P1
˚
a (A)
13.5828(5)
14.7056(6)
16.8850(7)
90
13.112(3)
13.975(3)
13.879(3)
90
9.0971(4)
12.1634(5)
18.6203(8)
90
9.0434(18)
14.838(3)
18.788(4)
81.12(3)
86.34(3)
73.67(3)
2389.8(8)
4
13.370(3)
12.149(2)
16.050(3)
90
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
90
93.31(3)
90
93.5230(10)
90
96.04(3)
90
3
˚
Cell volume (A )
3372.7(2)
8
1.623
2538.9(9)
4
1.731
2056.47(15)
4
1.570
2592. 6(9)
4
1.594
Z
Dc (g cmꢀ3
)
1.614
1.371
1188
l (mmꢀ1
F(000)
Crystal size (mm)
)
1.853
1680
1.428
1312
1.437
1000
1.360
1272
0.25 · 0.22 · 0.14 0.27 · 0.23 · 0.16
0.36 · 0.28 · 0.16 0.24 · 0.29 · 0.13
2.00–27.48
21992
0.36 · 0.27 · 0.18
1.89–27.10
26853
h limits (ꢁ)
2.37–26.37
31402
2.07–25.02
21941
1.10–25.03
21312
Reflections collected
Independent reflections [Rint
Data/restraints/parameters
Goodness on fit on F2
R1 (I > 2r(I))
]
3441 [0.0792]
3441/26/206
1.050
4487 [0.0560]
4487/11/299
1.055
4721 [0.0587]
4721/0/274
1.053
8442 [0.0680]
8442/159/630
0.930
5716 [0.0662]
5716/1/337
1.063
0.0475
0.1402
0.0427
0.1237
0.0429
0.1169
0.0520
0.1302
0.0454
0.1193
WR2 (all data)
Largest differential peak and hole (e A
ꢀ3
˚
)
0.755/ꢀ0.600
1.076/ꢀ0.793
0.457/ꢀ0.340
0.603/ꢀ0.482
0.855/ꢀ0.649

1210
L. Busetto et al. / Inorganica Chimica Acta 358 (2005) 1204–1216
R
M
N
C
OC
Fe
Fe
R = Xyl, trans-2a
Me, trans-2b
C
O
NCS
+ [NBu4][SCN]
in THF, RT
+
R
Me
Fe
N
C
THF, reflux
OC
NCMe
Fe
C
O
R
Me
N
+ [NBu4][SCN]
in THF, reflux
R = Xyl, 1a
Me, 1b
OC
C
NCS
R = Xyl, cis-2a
Me, cis-2b
Fe
Fe
C
O
Scheme 1.
Table 2
Selected bond lengths (A) and angles (ꢁ) for complex trans-2b
O11
˚
Fe(1)–Fe(2)
Fe(2)–C(11)
Fe(1)–C(12)
Fe(2)–C(12)
Fe(1)–C(13)
Fe(2)–C(13)
2.518(1)
1.754(5)
1.880(4)
1.974(5)
1.855(4)
1.874(4)
Fe(1)–N(2)
N(2)–C(16)
C(16)–S(1)
C(11)–O(11)
C(12)–O(12)
C(13)–N(1)
1.932(3)
1.151(5)
1.622(4)
1.148(6)
1.170(5)
1.297(5)
C14
C11
C15
N1
C13
Fe(1)–C(12)–Fe(2)
Fe(1)–C(13)–Fe(2)
81.55(18)
84.96(17)
Fe(1)–N(2)–C(16)
N(2)–C(16)–S(1)
169.7(3)
178.4(4)
Fe2
Fe1
C12
O12
N2
acetylides LiCCR (R = Me, Tol) to 3 results in the elim-
ination of S(Me)(CCR) with consequent formation of
the known compound cis-[Fe2{l-CN(Me)(Xyl)}(l-
CO)(CO)(CN)(Cp)2], in about 80% yield [9b].
C16
S1
Similarly to what reported for the preparation of 2,
the complexes cis-[M2{l-CN(Me)(R)}(l-CO)(CO)(N-
CO)(Cp)2] (M = Fe, R = Me (4a); M = Ru, R = Xyl
(4b); M = Ru, R = Me (4c)) and cis-[M2{l-
CN(Me)(R)}(l-CO)(CO)(N3)(Cp)2] (M = Fe, R = Xyl
(5a); M = Fe, R = Me (5b); M = Ru, R = Xyl (5c)) are
obtained by heating at reflux temperature [M2{l-
CN(Me)(R)}(l-CO)(CO)(MeCN)(Cp)2][SO3CF3] (M =
Fe, R = Xyl (1a); M = Fe, Me (1b); M = Ru, R = Xyl
(1c); M = Ru, R = Me (1d)) in THF in the presence of
NaNCO and NaN3, respectively (Scheme 3). Complexes
4–5 are obtained in good yields (65–76%) after column
chromatography.
Fig. 1. Molecular structure of trans-2b, with key atoms labelled (all H
atoms have been omitted). Displacement ellipsoids are at 30%
probability level.
Complex cis-2a reacts with CF3SO3Me to give
cis-[Fe2{l-CN(Me)(Xyl)}(l-CO)(CO)(NCSMe)(Cp)2]
[CF3SO3] (3) (Scheme 2), as clearly indicated by the spec-
troscopic data (see Experimental). Addition of lithium

L. Busetto et al. / Inorganica Chimica Acta 358 (2005) 1204–1216
1211
Xyl
Me
Fe
Xyl
Me
Fe
Xyl
Me
+
N
C
N
C
N
C
OC
OC
NCS
OC
CN
NCSMe
+ RCCLi
+ CF3SO3Me
Fe
Fe
Fe
Fe
- S(Me)(CCR)
C
O
C
O
C
O
cis-2a
3
Scheme 2.
+
R
N
Me
M
R
Me
N
C
OC
NCMe
OC
C
X
+ NaX at reflux
in THF
M
M
M
C
O
C
O
R
M
X
R
M
Fe
Ru
Ru
Fe
Fe
Ru
Xyl Fe 1a
Me Fe 1b
Xyl Ru 1c
Me Ru 1d
NCO Me
NCO Xyl
NCO Me
N3
N3
N3
4a
4b
4c
5a
5b
5c
Xyl
Me
Xyl
Scheme 3.
The molecular structures of 4b and 5a are reported in
Figs. 2 and 3, whereas the main bond lengths and bond
angles are reported in Tables 3 and 4. The Cp ligands
show in both the molecules a cis arrangement relative
to the M2(l-C)2 core; moreover, the Xyl substituents
in the l-CN(Me)(Xyl) ligand points, towards the termi-
nal CO in both 4b and 5a, as previously found in anal-
ogous diiron and diruthenium complexes [10c,18]. The
O2
O11
C14
C23
O11
C11
C15
C15
C14
N4
N1
C11
N3
N2
N1
N2
C13
C13
Ru1
Ru2
Fe2
Fe1
C12
C12
O12
O12
Fig. 2. Molecular structure of 4b, with key atoms labelled (all H atoms
have been omitted). Displacement ellipsoids are at 30% probability
level.
Fig. 3. Molecular structure of 5a, with key atoms labelled (all H atoms
have been omitted). Displacement ellipsoids are at 30% probability
level.

1212
L. Busetto et al. / Inorganica Chimica Acta 358 (2005) 1204–1216
Table 3
Xl
Me
Me
Xyl
˚
Selected bond lengths (A) and angles (ꢁ) for complex 4b
N
C
N
C
Ru(1)–Ru(2)
Ru(2)–C(11)
Ru(1)–C(12)
Ru(2)–C(12)
Ru(1)–C(13)
Ru(2)–C(13)
2.7005(8)
1.850(6)
1.981(6)
2.108(5)
1.940(5)
1.991(5)
Ru(1)–N(2)
N(2)–C(23)
C(23)–O(2)
C(11)–O(11)
C(12)–O(12)
C(13)–N(1)
2.088(5)
1.138(8)
1.213(8)
1.143(7)
1.166(7)
1.304(6)
OC
OC
N3
N3
Fe
Fe
)
Fe
Fe
)
C
O
C
O
Fe(1)–C(12)–Fe(2)
Fe(1)–C(13)–Fe(2)
82.6(2)
86.8(2)
Fe(1)–N(2)–C(16)
N(2)–C(16)–S(1)
167.0(35)
177.8(8)
Major
Minor
Scheme 4.
gand (d ca. 211 ppm M = Fe; 200 ppm M = Ru). The
carbon of the NCO ligand in 4 resonates at ca. 128
ppm as expected for isocyanate ligands.
The azido complexes 5 react in THF solution at re-
flux with electron poor alkynes such as MeO2CC„C-
CO2Me and HC„CCO2Me affording the triazolato
complexes [M2{l-CN(Me)(R)}(l-CO)(CO){N3C2(CO2-
Me)2}(Cp)2] (M = Fe, R = Xyl (6a); M = Fe, R = Me
Table 4
˚
Selected bond lengths (A) and angles (ꢁ) for complex 5a
Fe(1)–Fe(2)
Fe(2)–C(11)
Fe(1)–C(12)
Fe(2)–C(12)
Fe(1)–C(13)
Fe(2)–C(13)
2.4999(6)
1.753(4)
1.882(3)
1.968(3)
1.849(3)
1.877(3)
Fe(1)–N(2)
N(2)–N(3)
N(3)–N(4)
C(11)–O(11)
C(12)–O(12)
C(13)–N(1)
2.009(3)
1.187(4)
1.161(5)
1.143(4)
1.173(4)
1.304(4)
Fe(1)–C(12)–Fe(2)
Fe(1)–C(13)–Fe(2)
80.94(14)
84.29(13)
Fe(1)–N(2)–C(16)
N(2)–C(16)–S(1)
120.1(3)
176.8(5)
(6b);
M = Ru,
R = Xyl
(6c))
and
[M2{l-
CN(Me)(R)}(l-CO)(CO){N3C2(H)(CO2Me)}(Cp)2]
(M = Fe, R = Me (7a); M = Ru, R = Xyl (7b)) (Scheme
5). In a similar fashion, the reaction of 5a with fumaro-
nitrile (NC)(H)C@C(H)(CN) under analogous condi-
tions affords the triazolato product [Fe2{l-CN(Me)
(Xyl)}(l-CO)(CO){N3C2(H)(CN)}(Cp)2] (8). All these
products have been obtained in good yields (70–90%)
after column chromatography and fully characterised
spectroscopically via IR and NMR. Moreover, the
molecular structures of 6b and 8 have been determined
by X-ray diffraction studies (Figs. 4 and 5, and Tables
5 and 6). The formation of 6–8 proceeds via [3+2] cyclo-
addition of the alkyne or the alkene, as previously dem-
onstrated for mononuclear azido complexes [7,20]; in
the case of 8, the reaction is accompanied by loss of
HCN.
The asymmetric unit of 6b contains two independent
molecules, with similar relative arrangement of the
atoms, similar bond lengths and bond angles but oppo-
site absolute structure. The molecular structures of 6b
and 8 exhibit a cis arrangement of the Cp ligands; more-
over, in the case of 8 where the bridging aminocarbyne
ligand is asymmetrically substituted, the bulkier Xyl
group points in the direction of the terminal CO ligand.
The triazolato ligand is N(2) coordinated in 6b, whereas
it is bound to iron via N(1) in 8. Both these coordina-
tions mode of the triazolato ligand have been previously
reported [20a]; molecular orbital calculations [21] indi-
cate that these two bonding modes are essentially isoen-
ergetic. Evidence obtained to date indicates that either
two isomers N(1) and N(2) are formed simultaneously
or only the N(2) isomer is produced exclusively
[7,20c,22]. Our work completely support this hypothe-
sis; in fact, in the case of complexes 6 which contain
metal–isocyanate linkage in 4b is approximately linear
[bond angles Ru(1)–N(2)–C(23) 167.0(5) and N(2)–
C(23)–O(2) 177.8(8)ꢁ], and the C(23)–N(2) distance
˚
[1.138(8) A] is significantly shorter than C(23)–O(2)
˚
[1.213(8) A], implying some triple bond character for
the former. This is a clear indication of the N-coordina-
tion of the NCOꢀ ligand, as previously demonstrated in
complexes such as [Cr(Cp)(NCO)(NO)2] [19] and
[M(Cp)2(NCO)2] (M = Ti, Zr) [5]. Conversely, the azido
ligand in 5a shows a bent coordination [bond angle
Fe(1)–N(2)–N(3) 120.1(3)ꢁ] and the Fe(1)–N(2) dis-
˚
tance [2.009(3) A] is characteristic for a r-interaction,
as found in the analogous amino complex [Fe2-
{l-CN(Me)2}(l-CO)(CO)(EtNH2)(Cp)2][SO3CF3][Fe–N
˚
2.018(9) A] [18].
The IR spectra of 4–5 show m(CO) for the terminal
and bridging carbonyls at ca. 1980 and 1800 cmꢀ1
,
respectively; the former data well agree with a cis geom-
etry of the Cp ligands also in solution. Moreover, com-
plexes 4 show m(NCO) at ca. 2235 cmꢀ1, whereas m(N3)
in 5 absorbs at ca. 2030 cmꢀ1. The NMR spectra of
4–5 show the presence of a single species in solution, ex-
cept for 5a where a second isomer is present (major:mi-
nor = 10). This is probably due to a different orientation
of the Me and Xyl substituents on the l-CN(Me)(Xyl)
ligand (Scheme 4), as previously found in analogous
diiron and diruthenium l-aminocarbyne complexes
[10c,18]. The most important feature of the 13C NMR
spectra is the presence of three resonances at low fields
attributable to the l-aminocarbyne carbon (d ca. 340
ppm M = Fe; 310 ppm M = Ru), the l-CO (d ca. 266
ppm M = Fe; 236 ppm M = Ru) and the terminal CO li-
a
symmetrically disubstituted triazolato ligand

L. Busetto et al. / Inorganica Chimica Acta 358 (2005) 1204–1216
1213
CO2Me
Me
M
R
CO2Me
R
N
N
C
OC
N
N
M
Xyl Fe
Me Fe
Xyl Ru
6a
6b
6c
M
C
O
+ MeO2CC
CCO2Me
CO2Me
R
Me
M
N
N
C
Me
M
R
N
H
N
OC
N3
N
OC
C
R
M
CH
+ MeO2CC
Me Fe
Xyl Ru
7a
7b
M
M
C
O
C
O
5
CN
+ (NC)(H)C=C(H)(CN)
N
Me
Xyl
Fe
N
H
N
N
OC
C
Fe
8
C
O
Scheme 5.
C21
O1
O4
C19
N5
N4
C25
C18
C20
O3
O2
N3
C24
C17
C16
C14
O11
C15
N3
N4
N1
O11
C15
C23
C14
N1
C11
N2
N2
H23
C13
C11
C13
Fe1
Fe1
Fe2
Fe2
C12
O12
C12
O12
Fig. 4. Molecular structure of 6b, with key atoms labelled (all H atoms
have been omitted). Displacement ellipsoids are at 30% probability
level. Only one of the two independent molecules is represented.
Fig. 5. Molecular structure of 8, with key atoms labelled (all H atoms,
except H23, have been omitted). Displacement ellipsoids are at 30%
probability level.

1214
L. Busetto et al. / Inorganica Chimica Acta 358 (2005) 1204–1216
Table 5
are formed as a mixture of N(1) and N(2) isomers
(Scheme 6).
˚
Selected bond lengths (A) and angles (ꢁ) for the two independent
molecules of complex 6b
The IR spectra for 6–8 show two m(CO) at frequencies
similar to the starting azido complexes 5, indicating a
similar electronic character of the two ligands. As a con-
sequence of the symmetrical N(2) coordination, the car-
bon atoms of the triazolato ligand and the two COOMe
substituents in 6 are equivalent and give rise to single
NMR resonances [e.g., dH 3.7–3.8 ppm for CO2Me; dC
ca. 162, 140 and 52 ppm for N3C2(CO2Me)2,
N3C2(CO2Me)2 and N3C2(CO2Me)2, respectively]. Con-
versely, for 7–8 two sets of resonances are present for the
N(2) and N(1) isomers [N(2):N(1) isomer ratio = 1.1–
2:1]. NOE studies clearly indicate that the major isomer
is the N(1)-bound, which is the one also present in the
solid state for 8. For instance, irradiation of the triazo-
lato proton (dH 7.74 ppm) in the major isomer of 8 pro-
duces a strong enhancement of the resonance of one Cp
ligand, whereas no effect is observed after irradiation of
the corresponding resonance in the minor isomer (dH
7.46 ppm).
Fe(1)–Fe(2)
Fe(2)–C(11)
Fe(1)–C(12)
Fe(2)–C(12)
Fe(1)–C(13)
Fe(2)–C(13)
Fe(1)–N(2)
N(2)–N(3)
2.5200(11)
1.753(5)
1.881(5)
1.968(5)
1.842(5)
1.885(4)
1.998(4)
1.318(5)
1.330(5)
1.362(6)
1.347(6)
1.391(6)
1.149(6)
1.176(5)
1.305(5)
Fe(3)–Fe(4)
Fe(4)–C(41)
Fe(3)–C(42)
Fe(4)–C(42)
Fe(3)–C(43)
Fe(4)–C(43)
Fe(3)–N(6)
N(6)–N(7)
2.5062(11)
1.755(6)
1.861(5)
1.969(5)
1.845(5)
1.877(5)
1.989(4)
1.315(5)
1.320(5)
1.369(6)
1.354(6)
1.383(6)
1.141(5)
1.178(5)
1.307(6)
N(2)–N(4)
N(6)–N(8)
N(3)–C(16)
N(4)–C(17)
C(16)–C(17)
C(11)–O(11)
C(12)–O(12)
C(13)–N(1)
N(7)–C(46)
N(8)–C(47)
C(46)–C(47)
C(41)–O(41)
C(42)–O(42)
C(43)–N(5)
Fe(1)–C(12)–Fe(2)
Fe(1)–C(13)–Fe(2)
Fe(1)–N(2)–N(3)
N(2)–N(3)–C(16)
N(3)–C(16)–C(17)
C(16)–C(17)–N(4)
C(17)–N(4)–N(2)
81.77(19)
85.06(19)
123.0(3)
105.0(4)
107.3(4)
108.5(4)
104.7(4)
Fe(3)–C(42)–Fe(4)
Fe(3)–C(43)–Fe(4)
Fe(3)–N(6)–N(7)
N(6)–N(7)–C(46)
N(7)–C(46)–C(47)
C(46)–C(47)–N(8)
C(47)–N(8)–N(6)
81.7(2)
84.6(2)
124.8(3)
104.9(4)
107.3(4)
108.3(4)
104.8(4)
The triazolato complexes 6–7 react in CH2Cl2
solution with CF3SO3Me affording the N-methyl-
ated
(l-CO)(CO){N3(Me)C2(CO2Me)2}(Cp)2][CF3SO3] (9)
and [M2{l-CN(Me)(R)}(l-CO)(CO){N3(Me)C2(H)
(CO2Me)}(Cp)2] [CF3SO3] (M = Fe, R = Me (10a);
M = Ru, R = Xyl (10b)), in good yields (90–95%)
(Scheme 7).
Their NMR spectra show the presence of a single spe-
cies in solution; NOE experiments on 10b clearly indi-
cate a strong interaction between one Cp ligand and
the CH proton of the triazole ring, suggesting that meth-
ylation occurs selectively at N(3) and the triazole is N(1)
coordinated. It is interesting to notice that in previous
works [7] a similar regiochemistry for the methylation
process was observed, but it was then followed by the re-
lease of the triazole molecule. Conversely, in our case
the complexes 9–10 are stable in solution and do not lose
the heterocycle ligand. In a similar way, the methylation
of 8 results in the nearly quantitative formation of the
cationic
complexes
[Fe2{l-CN(Me)(Xyl)}
Table 6
˚
Selected bond lengths (A) and angles (ꢁ) for complex 8
Fe(1)–Fe(2)
Fe(2)–C(11)
Fe(1)–C(12)
Fe(2)–C(12)
Fe(1)–C(13)
Fe(2)–C(13)
Fe(1)–N(2)
C(11)–O(11)
C(12)–O(12)
2.5084(8)
1.760(3)
1.880(3)
1.977(3)
1.863(2)
1.892(2)
1.970(2)
1.150(3)
1.179(3)
N(2)–N(3)
N(3)–N(4)
N(4)–C(24)
C(23)–C(24)
C(24)–C(25)
C(25)–N(5)
C(13)–N(1)
C(14)–N(1)
1.351(2)
1.326(4)
1.336(4)
1.377(4)
1.432(4)
1.151(4)
1.305(3)
1.481(3)
Fe(1)–C(12)–Fe(2)
Fe(1)–C(13)–Fe(2)
Fe(1)–N(2)–N(3)
N(2)–N(3)–N(4)
81.10(10)
83.83(10)
122.66(18)
110.0(2)
N(3)–N(4)–C(24)
N(4)–C(24)–C(23)
C(24)–C(23)–N(2)
C(24)–C(25)–N(5)
107.1(2)
108.8(2)
106.7(2)
176.9(4)
N3C2(CO2Me)2, only the N(2)-bound isomer is formed
as shown by NMR data. Conversely, the complexes 7–
8, which possess a monosubstituted triazolato ligand,
complex
[Fe2{l-CN(Me)(Xyl)}(l-CO)(CO){N3(Me)-
R'
Me
R
Me
M
N
R
H
N
N
N
C
N
R'
OC
C
N
OC
M
N
N
M
H
M
C
O
C
O
N(2) Isomer
N(1) Isomer
Scheme 6.

L. Busetto et al. / Inorganica Chimica Acta 358 (2005) 1204–1216
1215
CO2Me
Me
+
Me
M
Me
N
R
R
R'
N
N
C
N
C
N
CO2Me
OC
N
OC
N
N
+ CF3SO3Me
M
M
R'
M
C
O
C
O
R
R'
M
R
R'
M
Xyl
Me
Xyl
CO2Me
H
H
Fe
Fe
Ru 7b
6a
7a
Xyl
Me
Xyl
CO2Me
H
H
Fe
Fe
Ru 10b
9
10a
Scheme 7.
Me
N
+
Me
Xyl
N
C
N
CN
OC
N
+
Fe
H
Fe
Me
Fe
Xyl
Fe
CN
H
C
O
N
N
N
N
OC
C
Me
N
+ CF3SO3Me
+
Me
Xyl
Fe
C
O
N
C
N
H
8
OC
N
CN
Fe
C
O
Scheme 8.
C2(H)(CN)}(Cp)2][CF3SO3] (11). The IR spectrum
shows the usual m(CO) for the terminal and bridging car-
bonyls at frequencies similar to those observed for 9–10,
and m(CN) at 2220 cmꢀ1; hence, also in this case meth-
ylation has occurred on the triazolato ring. The NMR
spectra show the presence of two isomers in a 1.2:1 ratio
and with very similar but distinct resonances. This can
be explained assuming that the methylation of 8 is not
regioselective, but it can occur on both N(1) and N(3)
(Scheme 8).
M = Ru, R = Me (1d)). We had previously shown that
nitrile substitution in 1 could be used also for the intro-
duction of other N-donor ligands, such as amines and
imines [18]. All these reactions are completely selective,
and no product of addition of the N-nucleophile has
been observed during our work, even though nucleo-
philic additions to coordinated nitriles have been widely
documented in the literature [23]. Probably, the MeCN
ligand in 1 is not sufficiently activated to react with N-
nucleophiles, whereas it reacts easily with C-nucleo-
philes [9a,9c,10c].
The results reported in this paper suggest that ni-
trile substitution in 1 proceeds with inversion of the
configuration of the metal-centre and, in fact, the
products obtained at room temperature present a
trans geometry of the Cp ligands, whereas the parent
complexes 1 have a cis structure. Moreover, trans to
cis isomerisation occurs at high temperature, indicat-
ing that the trans isomer is the kinetic product
4. Conclusions
This study shows that dimetallic aminocarbyne com-
plexes containing pseudohalide ligands can be obtained
by MeCN displacement from [M2{l-CN(Me)(R)}(l-
CO)(CO)(MeCN)(Cp)2][SO3CF3] (M = Fe, R = Xyl
(1a); M = Fe, Me (1b); M = Ru, R = Xyl (1c);

1216
L. Busetto et al. / Inorganica Chimica Acta 358 (2005) 1204–1216
[5] S.J. Anderson, D.S. Brown, K.J. Finney, J. Chem. Soc., Dalton
Trans. (1979) 152.
whereas the cis species is the thermodynamic one, as
previously found for the vinyliminium complexes
[Fe2{l-r:g3-C(R0)@C(R00)C@N(Me)(R)}(l-CO)(CO)(Cp)2]
[SO3CF3] [10a,10b].
[6] (a) H.W. Fruhauf, Chem. Rev. 97 (1997) 523;
(b) Z. Dori, R.F. Ziolo, Chem. Rev. 73 (1973) 247.
[7] C.W. Chang, G.H. Lee, Organometallics 22 (2003) 3107.
[8] (a) V.G. Albano, L. Busetto, C. Camiletti, C. Castellari, M.
Monari, V. Zanotti, J. Chem. Soc., Dalton Trans. (1997)
4671;
5. Supplementary material
(b) V.G. Albano, S. Bordoni, L. Busetto, C. Camiletti, M.
Monari, A. Palazzi, F. Prestopino, V. Zanotti, J. Chem.
Soc., Dalton Trans. (1997) 4665.
Crystallographic data for the structural analyses have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 253688 for trans-2b, 253689
for 4bÆCH2Cl2, 253690 for 5a, 253691 for 6bÆ0.5CH2Cl2
and 253692 for 8ÆCH2Cl2. Copies of this information
can be obtained free of charge from the Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(fax: +44 1233 336033; e-mail: deposit@ccdc.cam.ac.uk
or http://www.ccdc.cam.ac.uk).
[9] (a) V. G Albano, L. Busetto, F. Marchetti, M. Monari, V.
Zanotti, J. Organomet Chem. 649 (2002) 64;
(b) V.G. Albano, L. Busetto, M. Monari, V. Zanotti, J. Organo-
met. Chem. 606 (2000) 163;
(c) V.G. Albano, S. Bordoni, L. Busetto, F. Marchetti, M.
Monari, V. Zanotti, J. Organomet. Chem. 684 (2003) 37.
[10] (a) V.G. Albano, L. Busetto, F. Marchetti, M. Monari, S.
Zacchini, V. Zanotti, Organometallics 22 (2003) 1326;
(b) V.G. Albano, L. Busetto, F. Marchetti, M. Monari, S.
Zacchini, V. Zanotti, J. Organomet. Chem. 689 (2004) 528;
(c) L. Busetto, F. Marchetti, S. Zacchini, V. Zanotti, Eur.
J. Inorg. Chem. (2004) 1494.
[11] W. Wilker, D. Leibfritz, R. Kerssebaum, W. Beimel, Magn.
Reson. Chem. 31 (1993) 287.
Acknowledgements
[12] K. Stott, J. Stonehouse, J. Keeler, T.L. Hwang, A.J. Shaka,
J. Am. Chem. Soc. 117 (1995) 4199.
`
We thank the Ministero dellꢁUniversita e della Ric-
[13] SMART
&
SAINT Software Reference Manuals, Version
erca Scientifica e Tecnologica (MIUR) (project: ‘‘New
strategies for the control of reactions: interactions of
molecular fragments with metallic sites in unconven-
tional species’’) and the University of Bologna
(Funds for Selected Research Topics for financial
support.
5.051, Bruker Analytical X-Ray Instruments Inc., Madison,
WI, 1998.
[14] G.M. Sheldrick, SADABS, Program for empirical absorption
correction, University of Go¨ttingen, Germany, 1996.
[15] G.M. Sheldrick, SHELX-97, Program for crystal structure deter-
mination, University of Go¨ttingen, Germany, 1997.
[16] J.E. Huheey, Inorganic Chemistry, third ed., Harper International
SI edition, 1983, p. 513.
[17] T.E. Sloan, A. Wojcicki, Inorg. Chem. 7 (1968) 1268.
[18] L. Busetto, F. Marchetti, S. Zacchini, V. Zanotti, E: Zoli,
J. Organomet. Chem. (available online 17 November 2004).
[19] M.A. Bush, G.A. Sim, J. Chem. Soc. (A) (1970) 605.
[20] (a) P. Paul, K. Nag, Inorg. Chem. 26 (1987) 2969;
(b) W. Rigby, P.M. Bailey, J.A. McCleverty, P.M. Maitlis,
J. Chem. Soc., Dalton Trans. (1979) 371;
References
[1] (a) P.M. Secondo, J.M. Land, R.G. Baughman, H.L. Collier,
Inorg. Chim. Acta 309 (2000) 13;
(b) K.B. Shiu, W.N. Guo, T.J. Chan, J.C. Wang, L.S. Liou, S.M.
Peng, M.C. Cheng, Organometallics 14 (1995) 1732;
(c) R. Vicente, A. Escuer, J. Ribas, X. Solans, Inorg. Chem. 3
(1992) 1726;
(c) T. Kemmerich, J.H. Nelson, N.E. Takach, H. Boeheme, B.
Jablonski, W. Beck, Inorg. Chem. 21 (1982) 1226.
[21] (a) J.H. Nelson, D.L. Schmitt, R.A. Henty, D.W. Moore, H.B.
Jonassen, Inorg. Chem. 9 (1970) 2678;
(d) R. Cortes, J.L. Pizzarro, L. Lezama, M.I. Arriortua, T. Rojo,
Inorg. Chem. 33 (1994) 2697.
(b) D.A. Redfield, J.H. Nelson, R.A. Henry, D.W. Moore, H.B.
Jonassen, J. Am. Chem. Soc. 96 (1974) 6298;
[2] J.L. Burmeister, Coord. Chem. Rev. 105 (1990) 77.
[3] (a) A.H. Norbury, Advances in Inorganic Chemistry and Radio-
chemistry, Academic Press, New York, 1975, p. 17;
(b) R.A. Bailey, S.L. Kozak, T.W. Michelsen, W.N. Mills, Coord.
Chem. Rev. 6 (1971) 407;
(c) R.L. Kieft, W.M. Peterson, G.L. Blundell, S. Horton, R.A.
Henry, H.B. Jonassen, Inorg. Chem. 15 (1976) 1721.
[22] P.H. Kreutzer, J.C. Weis, H. Bock, J. Erbe, W. Beck, Chem. Ber.
116 (1983) 2691.
[23] (a) R.A. Michelin, M. Mozzon, R. Bertani, Coord. Chem. Rev.
147 (1996) 299;
(c) A.M. Golub, H. Kohler, V.V. Skopenko, Chemistry of
Pseudo-halides, Elsevier, New York, 1986.
(b) V.Y. Kukushkin, A.J.L. Pombeiro, Chem. Rev. 102 (2002)
1771.
[4] (a) J. Nelson, S.M. Nelson, J. Chem. Soc. (1969) 1597;
(b) G. Thiele, P. Hilfrich, Z. Naturforsch., Teil B 30 (1975) 19.