Vanadium (β-(dimethylamino)ethyl)cyclopentadienyl complexes with diphenylacetylene ligands

Article abstract of DOI:10.1021/om8000718

Reduction of the V(III) (β-(dimethylamino)ethyl)cyclopentadienyl dichloride complex [η⁵:η¹-C₅H ₄(CH₂)₂NMe₂]VCl₂(PMe ₃)(1) with 1 equiv of Na/Hg yielded the

Full text of DOI:10.1021/om8000718

2316
Organometallics 2008, 27, 2316–2320
Vanadium (ꢀ-(Dimethylamino)ethyl)cyclopentadienyl Complexes
with Diphenylacetylene Ligands
Guohua Liu,*,† Xiaoquan Lu,† Marcella Gagliardo,‡ Dirk J. Beetstra,‡ Auke Meetsma,‡ and
Bart Hessen*,‡
Department of Chemistry, College of Life and EnVironmental Science, Shanghai Normal UniVersity,
Shanghai 200234, People’s Republic of China, and Center for Catalytic Olefin Polymerization, Stratingh
Institute for Chemistry and Chemical Engineering, UniVersity of Groningen, Nijenborgh 4,
9747 AG Groningen, The Netherlands
ReceiVed January 26, 2008
Reduction of the V(III) (ꢀ-(dimethylamino)ethyl)cyclopentadienyl dichloride complex [η5:η1-
C5H4(CH2)2NMe2]VCl2(PMe3)(1)with1equivofNa/HgyieldedtheV(II)dimer{[η5:η1-C5H4(CH2)2NMe2]V(µ-
Cl)}2 (2). This compound reacted with diphenylacetylene in THF to give the V(II) alkyne adduct [η5:η1-
C5H4(CH2)2NMe2]VCl(η2-PhCt CPh) (3). Further reduction of 2 with Mg in the presence of diphenylacetylene
resulted in oxidative coupling of two diphenylacetylene groups to yield the diamagnetic, formally V(V), bent
metallacyclopentatriene complex [η5:η1-C5H4(CH2)2NMe2]V(C4Ph4) (4).
Amino-functionalized cyclopentadienyl transition-metal com-
functionality can reversibly dissociate from the metal center.
This behavior can strongly affect the reactivity of such
complexes: for instance, in catalytic conversions.4 Recently, we
described the chemistry of the vanadium(III) complex (η5:η1-
C5H4CH2CH2NMe2)VCl2(PMe3),5 containing a (ꢀ-(dimethyl-
amino)ethyl)cyclopentadienyl ligand, which seemed to us to be
a suitable starting material for the development of new orga-
novanadium chemistry.6 Also, we observed that the tendency
of the pendant amino group to bind to or dissociate from the
vanadium center depends strongly on the nature of the other
ligands bound to the vanadium atom.
In this contribution, we present the chemistry of the dimeric
vanadium(II) (ꢀ-(dimethylamino)ethyl)cyclopentadienyl com-
plex {[η5:η1-C5H4(CH2)2NMe2]V(µ-Cl)}2 (2). It has been found
that the reaction of 2 with diphenylacetylene produces the V(II)
alkyne adduct [η5:η1-C5H4(CH2)2NMe2]VCl(η2-PhCt CPh) (3)
and reduction of 2 with Mg in the presence of diphenylacetylene
results in the formation of the bent V(V) metallacyclopentatriene
complex [η5:η1-C5H4(CH2)2NMe2]V(C4Ph4) (4), in which the
Lewis basic amino group can bind to the vanadium center
through the chelate effect.
plexes have attracted much attention, owing to their dramatic
effect on catalytic function compared to the case for the
corresponding parent complexes.1 Playing a major role in this
area are titanium and chromium complexes, which exhibit good
activity in ethene and propene polymerization.2 However, there
are relatively few reports concerning vanadium complexes of
this type.3 This is mainly due to the fact that such compounds
are extremely air-sensitive and paramagnetic, due to the inherent
instability of monocyclopentadienyl vanadium analogues. The
limiting step in the development of this chemistry has been the
absence of suitable organometallic vanadium starting materials.
Amino-functionalized cyclopentadienyl ligands with additional
pendant Lewis basic functionalities have been used to enhance
the stability of metal complexes through the chelate effect, thus
leading to interesting products. It has been recognized that such
ligands can exhibit hemilabile behavior, in which the pendant
* To whom correspondence should be addressed. Tel: +86-21-64321819.
Fax: +86-21-64322511. E-mail: ghliu@shnu.edu.cn.
† Shanghai Normal University.
‡ University of Groningen.
(1) (a) Baretta, A.; Chong, K. S.; Cloke, F. G. N.; Feigenbaum, A.;
Green, M. L. H. J. Chem. Soc., Dalton Trans. 1983, 86, 1–864. (b) Jutzi,
P.; Redeker, T. Eur. J. Inorg. Chem. 1998, 663–674. (c) Britovesk, G. J. P.;
Gibson, V. C.; Wass, D. F. Angew. Chem., Int. Ed. 1999, 38, 428–447. (d)
Arndt, S.; Okuda, J. Chem. ReV. 2002, 102, 1953–1976. (e) Schrock, R. R.
Chem. ReV. 2002, 102, 145–179.
Results and Discussion
Synthesis and Molecular Structure of {[η5:η1-C5H4-
(CH2)2NMe2]V(µ-Cl)}2 (2). The vanadium (ꢀ-(dimethylamino)-
ethyl)cyclopentadienyl complex [η5:η1-C5H4(CH2)2NMe2]-
VCl2(PMe3) (1)5 was prepared in high yield by a straightforward
reaction between VCl3(PMe3)2 and Li[C5H4(CH2)2NMe2] in
THF. One-electron reduction of the V(III) complex 1 with 1
equiv of Na/Hg in THF afforded the red-violet dinuclear V(II)
chloride-bridged complex {[η5:η1-C5H4(CH2)2NMe2]V(µ-Cl)}2
(2; eq 1) in 56% isolated yield. Due to its paramagnetism, the
1H NMR spectrum of 2 only shows a very broad resonance for
(2) (a) Flores, J. C.; Chien, J. C. W.; Rausch, M. D. Organometallics
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(f) van Beek, J. A. M.; Gruter, G. J. M. EP 0805142 A1, 1997, issued to
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WO 97/23493, 1997, issued to DSM NV. (h) van Beek, J. A. M.; van
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Ed. 2001, 40, 2516–2519. (b) Deckers, P. J. W.; Hessen, B.; Teuben, J. H.
Organometallics 2002, 21, 5122–5135. (c) de Bruin, T. J. M.; Magna, L.;
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2004, 23, 3914–3920.
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10.1021/om8000718 CCC: $40.75
2008 American Chemical Society
Publication on Web 04/19/2008

Vanadium Cyclopentadienyl Complexes
Organometallics, Vol. 27, No. 10, 2008 2317
to bind the PMe3 ligand. This behavior was also observed for
the CpVCl(PR3) system (R ) Et, Me), although for R ) Me it
was seen that the equilibrium may be shifted to the side of
CpVCl(PMe3)2 when an excess of PMe3 is added.6g
(1)
Reaction of 2 with Diphenylacetylene: Synthesis and
Molecular Structure of [η5:η1-C5H4(CH2)2NMe2]VCl(η2-
PhCt CPh) (3). Reaction of metal chloride complexes with
alkynes can result in highly interesting derivatives.10 However,
for vanadium compounds, only several examples have been
reported.11 In this case, when a toluene solution of 2 was treated
with 1 equiv of phenylacetylene at ambient temperature, no
reaction was observed and 2 could be recovered unchanged.
However, when the same reaction was performed in THF
solution, the V(II) diphenylacetylene adduct [η5:η1-C5H4-
(CH2)2NMe2]VCl(η2-PhCt CPh) (3) was isolated as red crystals
in 57% yield after recrystallization from pentane. Apparently,
the coordination of the alkyne to the V(II) center is thermody-
namically favorable, but diphenylacetylene is kinetically unable
to cleave the (µ-Cl)2 bridge in dinuclear 2. Although the low-
valent metal center is expected to have a relatively low affinity
for THF, the ether apparently is kinetically competent to cleave
2 to give a transient monoclear THF adduct, from which the
THF subsequently is displaced by the alkyne (eq 2). The alkyne
adduct 3 was characterized by single-crystal X-ray diffraction,
and its structure is shown in Figure 2 (selected bond lengths
and angles are given in Table 2). Its structure is geometrically
similar to that of the V(I) complex CpV(PMe3)2(η2-
PhCt CPh).6b In the latter, the alkyne Ct C bond lies ap-
proximately in the same plane as one of the V-P bonds. In 3
the alkyne is similarly oriented relative to the V-N bond. As
was observed in CpV(PMe3)2(η2-PhCt CPh), the bonding of
the cyclopentadienyl moiety to vanadium in 3 is noticeably
distorted from the regular η5 mode, with the longest V-C
distances to C(3) and C(4) (2.35–2.36 Å) and the shortest to
C(1) (2.24 Å). A closer look at the coordinated alkyne reveals
that both the Ct C distance of 1.312(3) Å and the C-C-C(Ph)
angles of 139° are indications of a somewhat lesser extent of
π-back-donation in the V(II) complex 3 than in the V(I) complex
CpV(PMe3)2(η2-PhCt CPh), where the related parameters are
1.328(3) Å and 136°.
Figure 1. Molecular structure of {[η5:η1-C5H4(CH2)2NMe2]V(µ-
Cl)}2 (2). Thermal ellipsoids are drawn at the 50% probability level.
Hydrogen atoms are omitted for clarity.
Table 1. Selected Bond Lengths (Å) and Angles (deg) for 2
V(1)-Cl(1)
2.443(2)
2.434(2)
2.430(2)
2.454(2)
2.251(5)
2.258(7)
92.78(7)
93.43(15)
93.81(14)
92.60(7)
V(1)-C(1)
V(1)-C(2)
V(1)-C(3)
V(1)-C(4)
V(1)-C(5)
2.277(7)
2.308(7)
2.326(7)
2.290(7)
2.253(7)
V(1)-Cl(2)
V(2)-Cl(1)
V(2)-Cl(2)
V(1)-N(1)
V(2)-N(2)
Cl(1)-V(1)-Cl(2)
Cl(1)-V(1)-N(1)
Cl(2)-V(1)-N(1)
Cl(1)-V(2)-Cl(2)
Cl(1)-V(2)-N(2)
Cl(2)-V(2)-N(2)
V(1)-Cl(1)-V(2)
V(1)-Cl(2)-V(2)
100.22(18)
91.21(17)
76.43(6)
76.16(6)
all protons. However, it is clear that 2 is a phosphine-free
complex, as confirmed by the disappearance of the PMe3 proton
resonances in the 1H NMR spectrum. A crystal structure
determination of 2 (Figure 1, with selected bond lengths and
angles given in Table 1) shows a puckered V2Cl2 core with the
cyclopentadienyl ligands in a cis arrangement. It strongly
resembles the dimeric V(II) monochloride triethylphosphine
complex [Cp(Et3P)V(µ-Cl)]2 reported previously,6g,h with very
similar V-Cl distances in the puckered V2Cl2 unit, which is
essentially equilateral. The V-Cl distances (2.443(2), 2.434(2),
2.430(2), and 2.454(2) Å) are comparable to those observed in
other chloride-bridged dimeric vanadium complexes (2.4128(15)
and 2.5365(15) Å in [V(dNAr)Cl2(dppm)]27 and 2.459(2) and
2.373(2) Å in {[(Me3Si)NCH2CH2]2N(Me3Si)}2V2(µ-Cl2)),8
although there are slight differences. Furthermore, the Cl-V-Cl
angles of 92.78(7) and 93.43(15)° in the dimeric complex 2
are obviously larger than those observed in a closely related
dimeric titanium complex (77.11(5), 78.21(7), and 78.63(7)° in
(C5H4)2TiCl)2),9 indicating the steric nature of the ꢀ-aminoethyl-
functionalized cyclopentadienyl ligand. Apparently the (Cp-
ethylamino)VCl fragment prefers to form dimeric 2 rather than
(6) (a) Nieman, J.; Scholtens, H.; Teuben, J. H. J. Organomet. Chem.
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Luttikhedde, H. J. G.; Teuben, J. H.; Petersen, J. L.; Jagner, S.; Huffman,
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(2)
Reduction of 2 in the Presence of Diphenylacetylene:
Synthesis and Molecular Structure of [η5:η1-C5H4(CH2)2-
NMe2]V(C4Ph4) (4). Further reduction of the V(II) complex 2
by Mg in THF in the presence of diphenylacetylene (performed
(8) Lorber, C.; Choukroun, R.; Donnadieu, B. Inorg. Chem. 2003, 42,
673–675.
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Chem. 1977, 7, 1645–1655.

2318 Organometallics, Vol. 27, No. 10, 2008
Liu et al.
are close to that of 1.876(7) Å in the vanadium(V) bicyclic
carbene-amide complex (Me3Si)2NVN(SiMe3)SiMe2CH2C(Ph)-
C(Ph)C(Ph)C(Ph)14 and are similar to those of 1.891(3) and
1.883 (3) Å in the vanadium(V) bis(carbene) complex
CpV(C4Me2Ph2)(PMe3).6b These results clearly indicate that 4
is a vanadium(V) bis(carbene) complex, similar to the dinuclear
molybdenum bis(carbene) complex Mo2Br2(dCHSiMe3)2-
(PMe3)4 (ModC ) 1.949(5) Å).15 These V-C bond distances
are consistent with VdC bond orders as reviewed by Mindiola
recently.16 In addition, the C-C distances within the metalla-
cycle are all similar in length, with the central C(17)-C(24)
distance being fractionally shorter. A contrast with the structure
of CpV(C4Me2Ph2)(PMe3) is that the metallacycle in 4 is bent
away from the cyclopentadienyl group (supine orientation of
the C4R4fragment), whereas in the former it is bent toward the
Cp group (prone orientation). In this sense 4 is similar to the
first bent metallacyclopentatriene to be structurally characterized,
CpMo(C4Ph4)Cl.17 In the 13C NMR spectrum of 4, the VdC
resonance is located at 263.6 ppm, essentially identical with
that in CpV(C4Ph4)(PMe3), and the resonance of both central
carbon atoms at 94.9 ppm is downfield from that in the reference
compound. The absence of potentially coordinating PMe3
ligands appears to facilitate the alkyne coupling reaction,
allowing it to occur even at relatively low temperature (-5 °C).
In contrast, the diphenylacetylene complex CpV(PhCt CPh)-
(PMe3)2 only reacts with additional diphenylacetylene at elevated
temperatures (60 °C) to form the metallacyclopentatriene
complex CpV(C4Ph4)PMe3.6b
Figure 2. Molecular structure of [η5:η1-C5H4(CH2)2NMe2]VCl(η2-
PhCt CPh) (3). Thermal ellipsoids are drawn at the 50% probability
level. Hydrogen atoms are omitted for clarity.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 3
V(1)-Cl(1)
2.3366(6) V(1)-C(1)
2.239(3)
2.284(3)
2.351(2)
2.360(3)
2.305(3)
88.66(9)
90.69(5)
V(1)-N(1)
2.276(3)
1.969(3)
2.003(2)
1.312(3)
38.56(9)
V(1)-C(2)
V(1)-C(16)
V(1)-C(17)
C(16)-C(17)
C(16)-V(1)-C(17)
V(1)-C(3)
V(1)-C(4)
V(1)-C(5)
N(1)-V(1)-C(17)
N(1)-V(1)-Cl(1)
Cl(1)-V(1)-C(16) 103.43(7)
Cl(1)-V(1)-C(17) 109.09(7)
C(15)-C(16)-C(17) 139.1(2)
(3)
N(1)-V(1)-C(16)
127.19(9)
C(16)-C(17)-C(18) 138.2(3)
at low temperature, -30 to –5 °C) resulted in the isolation of
a diamagnetic red crystalline compound that was characterized
by single-crystal X-ray diffraction as the bent metallacyclopen-
tatriene complex [η5η1-C5H4(CH2)2NMe2]V(C4Ph4) (4; eq 3).
It is likely to be formed by reduction of the vanadium to V(I)
and coordination of two alkyne molecules to the metal center
followed by an oxidative coupling of the diphenylacetylene
ligands to yield a metallacycle. It was observed previously that
the metallacycle of the formula CpV(C4R4)(PMe3) takes on a
bent metallacyclopentatriene structure rather than the more
common planar metallacyclopentadiene structure.6b The crystal
structure of 4 (Figure 3, with selected bond lengths and angles
given in Table 3) shows two short V-C bond distances of
1.888(5) and 1.895(4) Å, which are shorter than that of 1.922
Å in a benzylidene complex.13 Such short V-C bond distances
In conclusion, the vanadium(III) (ꢀ-(dimethylamino)ethyl)-
cyclopentadienyldichloridecomplex(η5:η1-C5H4CH2CH2NMe2)-
VCl2(PMe3) is a convenient precursor for synthesis of a range
of organometallic vanadium derivatives. It has also been
recognized that amino-functionalized cyclopentadienyl ligands
with additional pendant Lewis basic functionalities can enhance
the stability of the vanadium complexes through the chelate
effect, thus resulting in novel complexes.
Experimental Section
General Considerations. All manipulations were performed
under an inert nitrogen atmosphere, using standard Schlenk or
glovebox techniques. Pentane (Aldrich, anhydrous, 99.8%) was
passed over columns of Al2O3 (Fluka), BASF R3-11-supported Cu
oxygen svavenger, and molecular sieves (Aldrich, 4 Å). Diethyl
ether and THF (Aldrich, anhydrous, 99.8%) were dried over Al2O3
(Fluka). All solvents were degassed prior to use and stored under
nitrogen. Deuterated solvents (C6D6, THF-d8; Aldrich) were
vacuum-transferred from Na/K alloy prior to use. Starting materials:
(C5H4(CH2)2NMe2)VCl2(PMe3) was prepared according to the
reported method.6 1H NMR spectra were recorded on Varian VXR-
300 (300 MHz) spectrometers in NMR tubes sealed with a Teflon
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Arndt, P.; Baumann, W.; Spannenberg, A. Organometallics 2005, 24, 456–
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Vanadium Cyclopentadienyl Complexes
Organometallics, Vol. 27, No. 10, 2008 2319
g, 3.90 mmol) in 30 mL of dry THF. The deep purple solution
turned violet over 2 h. After it had been stirred overnight, the violet
THF solution was transferred into a new Schlenk flask and the
residual Hg was washed twice with 5 mL of THF. All the THF
solutions were combined, the volatiles were removed in vacuo, and
the resulting violet solid was stripped twice with 15 mL of pentane.
The violet-red solid was repeatedly extracted with 30 mL portions
of pentane. The violet-red extracts were filtered and concentrated
to 10 mL. Cooling to -30 °C produced violet-red crystals of 2
(0.98 g; 2.2 mmol; 56%). IR (Nujol mull): 635, 678, 754, 772,
786, 817, 920, 953, 996, 1022, 1046, 1098, 1117, 1167, 1210, 1236,
1267, 1323, 1377, 1402, 1461, 2831, 2887, 2910, 2942, 2963 cm-1
1H NMR (benzene-d6, 20 °C, 300 MHz): δ 50.69 (s), 47.68 (s),
35.89 (∆ν1/2 ) 1240 Hz), 31.19 (∆ν1/2 ) 749 Hz), 21.58 (∆ν1/2
.
)
480 Hz), 12.19 (∆ν1/2 ) 429 Hz), 11.18 (∆ν1/2 ) 342 Hz), -2.39
(∆ν1/2 ) 146 Hz), -4.59 (∆ν1/2 ) 240 Hz). Anal. Calcd for
C18H28Cl2N2V2: C, 48.56; H, 6.34; N, 6.29. Found: C, 48.53; H,
6.33; N, 6.09.
Preparation of [η5:η1-C5H4(CH2)2NMe2]VCl(η2-PhCt CPh) (3). A
solution of 2 (148 mg, 0.33 mmol) together with PhCt CPh (118
mg, 0.66 mmol) in 5 mL of THF was stirred overnight at room
temperature. The solvents were removed in vacuo, and the resulting
solid was stripped with two portions of 5 mL of ether. The red
solid was repeatedly extracted with 30 mL portions of ether. The
red extracts were filtered and concentrated to 5 mL. Cooling to
-30 °C produced red crystals of 3 (152 mg, 0.38 mmol, 57%). IR
(Nujol mull): 689, 722, 754, 773, 802, 912, 921, 1001, 1024, 1044,
168, 1098, 1260, 1377, 1461, 1498, 1587, 1603, 1636, 2854, 2924,
2954 cm-1. 1H NMR (benzene-d6, 20 °C, 300 MHz): δ 5.12 (∆ν1/2
) 11 Hz), 5.07 (∆ν1/2 ) 18 Hz), 4.89 (s, 2H, Ph), 4.87 (s, Ph),
4.86 (s, Ph), 4.66 (∆ν1/2 ) 12 Hz), 4.61 (s), 4.46 (s). Anal. Calcd
for C23H24ClNV: C, 68.92; H, 6.04; N, 3.49. Found: C, 69.11; H,
5.89; N, 3.36.
Figure 3. Molecular structure of the cation of [η5:η1-C5H4-
(CH2)2NMe2]V(C4Ph4) (4). Thermal ellipsoids are drawn at the 50%
probability level. Hydrogen atoms have been omitted for clarity.
Table 3. Selected Bond Lengths (Å) and Angles (deg) for 4
V(1)-C(10)
1.888(5) C(10)-C(17)
1.895(4) C(24)-C(31)
2.360(5) C(17)-C(24)
2.339(5) V(1)-N(1)
1.433(6)
1.438(6)
1.417(5)
2.254(4)
116.32(15)
88.0(3)
V(1)-C(31)
V(1)-C(17)
V(1)-C(24)
C(10)-V(1)-C(31)
C(10)-V(1)-C(17)
C(17)-V(1)-C(24)
C(24)-V(1)-C(31)
N(1)-V(1)-C(10)
92.7(2)
N(1)-V(1)-C(31)
37.40(15) C(24)-C(31)-V(1)
35.11(14) V(1)-C(10)-C(17)
89.5(3)
37.91(16) C(17)-C(24)-C(31) 118.0(4)
112.60(15) C(10)-C(17)-C(24) 116.8(4)
Preparation of [η5:η1-C5H4(CH2)2NMe2]V(C4Ph4) (4). To
0.3 g of activated Mg (12.3 mmol) was added a solution of 2 (124
mg, 0.28 mmol) together with PhCt CPh (200 mg, 1.12 mmol) in
5 mL of THF at -30 °C. After 20 min, the solution changed from
violet to deep red. The solution was warmed to -5 °C over another
40 min. The solvent was removed in vacuo and the residue stripped
with two 5 mL portions of pentane. The brown-red solid was
repeatedly extracted with 30 mL of pentane. The extracts were
filtered and concentrated to 5 mL. Cooling to -30 °C produced
brown-red crystals of 4 (193 mg; 0.36 mmol; 59.6%). IR (Nujol
mull): 695, 721, 753, 773, 784, 828, 842, 925, 957, 995, 1023,
1071, 1097, 1113, 1152, 1262, 1326, 1377, 1461, 1484, 1584, 2853,
2923, 2951 cm-1. 1H NMR (benzene-d6, 20 °C, 300 MHz): δ 7.61,
7.59 (d, 4 H, Ph), 7.00–6.88 (m, 12 H, Ph), 6.37 (t, 2 H, J ) 2.1
Hz, Cp), 4.45 (t, 2 H, J ) 2.1 Hz, Cp), 1.79 (t, 2H, J ) 6.3 Hz,
Table 4. Crystallographic Data for 2-4
2
3
4
mol formula
fw
diffractometer
C18H28Cl2N2V2 C23H24ClNV
445.20 400.82
C37H34NV
543.59
SMART APEX SMART APEX SMART APEX
CCD
100(1)
monoclinic
P21/c
CCD
100(1)
trigonal
CCD
temp (K)
cryst syst
space group
a (Å)
b (Å)
c (Å)
100(1)
monoclinic
P21/n
j
R3
7.736(2)
16.663(3)
16.225(3)
99.529(3)
2062.6(8)
4
31.948(2)
31.948(2)
11.0765(7)
9.5142(9)
30.774(3)
10.501(1)
116.330(2)
2755.6(5)
4
ꢀ (deg)
V (Å3)
Z
9790.9(11)
18
dcalcd (g cm-3
F(000)
)
1.434
1.224
1.310
CpCH2), 1.44 (t, 2H, J ) 6.3 Hz, CH2N), 1.28 (s, 6 H, NMe2). 13
C
920
11.67
2.44, 26.02
0.2044
4062
3672
5.84
2.21, 28.28
0.1257
5403
1144
3.87
2.41, 24.73
0.1612
4842
ν(Mo KR), cm-1
θ range (deg)
Rw(F2)
NMR (benzene-d6, 20 °C, 75.4 MHz): δ 25.45 (t, CpCH2), 48.52
(q, NMe2), 69.70 (t, NCH2), 94.93 (b, CdC), 104.42 (b, Cp C),
123.70, 124.02, 125.14, 127.14, 127.39, 127.61, 133.91, 141.55,
150.92 (all, b, Ph C), 263.64 (b, VdC). Anal. Calcd for C37H34NV:
C, 81.75; H, 6.30; N, 2.58. Found: C, 81.75; H, 6.38; N, 2.50.
Structure Determinations. Suitable crystals for single-crystal
X-ray diffraction were obtained by cooling solutions of the
compounds in pentane (2 and 4) and diethyl ether (3). Crystals
were mounted on a glass fiber inside a drybox and transferred under
an inert atmosphere to the cold nitrogen stream of a Bruker SMART
APEX CCD diffractometer. Intensity data were collected with Mo
KR radiation (λ ) 0.710 73 Å). Intensity data were corrected for
Lorentz and polarization effects. A semiempirical absorption
correction was applied, based on the intensities of symmetry-related
reflections measured at different angular settings (SADABS18). The
structures were solved by Patterson methods, and extention of the
no. of indep
rflns
no. of params
R(F) for Fo >
4.0σ(Fo)
221
331
354
0.0736
0.0391
0.0678
GOF
largest diff
1.012
1.158
0.986
1.2(1), -0.7(1) 0.43(10), -0.28 1.12(10), -0.43
peak/hole (e Å-3
)
(Young) stopcock. IR spectra were recorded on a Mattson-4020
Galaxy FT-IR spectrometer from Nujol mulls between KBr disks
unless stated otherwise. Elemental analyses were performed by
Kolbe Analytical Laboratories, Mülheim a.d. Ruhr, Germany.
Preparation of {[η5:η1-C5H4(CH2)2NMe2]V(µ-Cl)}2 (2). Na
sand (0.090 g, 3.90 mmol) was added to 45 g of frozen Hg and
carefully dissolved by thawing out the Hg. When the Na/Hg was
at room temperature, it was added to a solution of complex 1 (1.30
(18) Sheldrick, G. M. SHELXL-97 Program for the Refinement of
Crystal Structures; University of Göttingen, Göttingen, Germany, 1997.

2320 Organometallics, Vol. 27, No. 10, 2008
Liu et al.
models was accomplished by direct methods applied to difference
structure factors using the grogram DIRDIF.19 Hydrogen atom
coordinates and isotropic thermal parameters were refined freely
unless mentioned otherwise. All refinements and geometry calcula-
tions were performed with the program packages SHELXL and
PLATON. Crystallographic data and details of the data collections
and structure refinements are given in Table 4.
Acknowledgment. We are grateful to the Shanghai
SciencesandTechnologiesDevelopmentFund(No.071005119)
and China National Natural Science Foundation (No.
20673072) for financial support.
Supporting Information Available: CIF files giving details of
the structure determinations of 2–4, including crystal data, positional
and thermal parameters, and interatomic distances and angles. This
materialisavailablefreeofchargeviatheInternetathttp:/pubs.acs.org.
(19) Spek, A. L. PLATON Program for the Automated Analysis of
Molecular Geometry, Version April 2000; University of Utrecht, Utrecht,
The Netherlands, 2000.
OM8000718