Synthesis of Vanadium (III), -(IV), and -(V) Complexes That Contain the Pentafluorophenyl-Substituted Triamicloamine Ligand [(C6F5NCH2CH2)3N] 3-

Article abstract of DOI:10.1021/ic951433j

[N₃N]V=O ([N₃N]_3- = [(C₆F₅NCH₂CH₂)₃N] ^3-) was prepared from VOCl₃ and H₃[N₃N] in the presence of Et₃N. Related arylimido complexes, [N₃N]V=NAr (Ar = p-MeC₆H₄, p-CF₃C₄H₄, or p-FC₆H₄), were prepared in high yields from the known V(NAr)Cl₃(THF) complexes in a similar manner or by treating [N₃N]V=O with an aryl isocyanate in refluxing m-xylene. New imido complexes also were prepared by reacting an imido complex with an aryl isocyanate over a period of 2 days in refluxing mesitylene. The reaction between VCl₃(THF)₃ and H₃[N₃N] in the presence of triethylamine gave [HNEt₃]{[N₃N]VCl} (3) when the reaction was carried out in ether and [N₃N]V(CH₃CN) (4a) when carried out in acetonitrile, while the reaction between VCl₃(THF)₃ and H₃[N₃N] in the presence of triethylamine and tert-butyl isocyanide gave green [N₃N] V(t-BuNC). [N₃N]V(CH₃CN) reacts with propylene oxide to give [N₃N]V=O and with diazoalkanes to give [N₃N]V=NN=CHR (R = SiMe₃, CO₂C₂H₅). An X-ray structure determination of 4a (C₂₆H₁₅N₅F₁₅V, a = 13.021(1) ?, b = 13.021(1) ?, c = 14.221(1) ?, γ = 120°, rhombohedral, R3 (h), Z = 3) shows it to be a pseudo-trigonal-bipyramidal species with acetonitrile coordinated in the apical position. An attempt to prepare the iodo analog of 3 by adding Me₃SiI in THF to it yielded green crystalline [N₃N]V(THF) (S). An X-ray structure determination of 5 (C₂₈H₂₀N₄F₁₅OV, a = 15.390(7) ?, b = 12.189(6) ?, c = 16.468(7) ?, β= 109.96 (3)°, monoclinic, P2₁/n, Z = 4) shows it to be a pseudo trigonal bipyramid containing 1 equiv of THF in the axial position in a structure that otherwise is similar to that of 4a. [HNEt₃]{[N₃N]VCl} reacts with ferrocenium triflate to yield [N₃N]VCl, a species that can be reduced to 5 in THF by sodium amalgam.

Full text of DOI:10.1021/ic951433j

Inorg. Chem. 1996, 35, 3695-3701
3695
Synthesis of Vanadium(III), -(IV), and -(V) Complexes That Contain the
Pentafluorophenyl-Substituted Triamidoamine Ligand [(C6F5NCH2CH2)3N]3-
Kotohiro Nomura, Richard R. Schrock,* and W. M. Davis
Department of Chemistry 6-331, Massachusetts Institute of Technology,
Cambridge, Massachusetts 02139
ReceiVed NoVember 9, 1995X
[N3N]VdO ([N3N]3- ) [(C6F5NCH2CH2)3N]3-) was prepared from VOCl3 and H3[N3N] in the presence of Et3N.
Related arylimido complexes, [N3N]VdNAr (Ar ) p-MeC6H4, p-CF3C6H4, or p-FC6H4), were prepared in high
yields from the known V(NAr)Cl3(THF) complexes in a similar manner or by treating [N3N]VdO with an aryl
isocyanate in refluxing m-xylene. New imido complexes also were prepared by reacting an imido complex with
an aryl isocyanate over a period of 2 days in refluxing mesitylene. The reaction between VCl3(THF)3 and H3-
[N3N] in the presence of triethylamine gave [HNEt3]{[N3N]VCl} (3) when the reaction was carried out in ether
and [N3N]V(CH3CN) (4a) when carried out in acetonitrile, while the reaction between VCl3(THF)3 and H3[N3N]
in the presence of triethylamine and tert-butyl isocyanide gave green [N3N]V(t-BuNC). [N3N]V(CH3CN) reacts
with propylene oxide to give [N3N]VdO and with diazoalkanes to give [N3N]VdNNdCHR (R ) SiMe3,
CO2C2H5). An X-ray structure determination of 4a (C26H15N5F15V, a ) 13.021(1) Å, b ) 13.021(1) Å, c )
14.221(1) Å, γ ) 120°, rhombohedral, R3 (h), Z ) 3) shows it to be a pseudo-trigonal-bipyramidal species with
acetonitrile coordinated in the apical position. An attempt to prepare the iodo analog of 3 by adding Me3SiI in
THF to it yielded green crystalline [N3N]V(THF) (5). An X-ray structure determination of 5 (C28H20N4F15OV,
a ) 15.390(7) Å, b ) 12.189(6) Å, c ) 16.468(7) Å, â ) 109.96 (3)°, monoclinic, P21/n, Z ) 4) shows it to be
a pseudo trigonal bipyramid containing 1 equiv of THF in the axial position in a structure that otherwise is
similar to that of 4a. [HNEt3]{[N3N]VCl} reacts with ferrocenium triflate to yield [N3N]VCl, a species that can
be reduced to 5 in THF by sodium amalgam.
Introduction
posed to be the sodium salt of the d4 “Mo(II)” species
{[(C6F5NCH2CH2)3N]Mo(N2)}-, i.e., [(C6F5NCH2CH2)3N]Mos
A variety of vanadium complexes that contain triamidoamine
ligands of the type [(RNCH2CH2)3N]3- (where R is a trialkyl-
silyl group) have been reported.1-6 Initially we were surprised
that the “trigonal monopyramidal” versions3 do not bind
dinitrogen for several reasons. First, a variety of vanadium
dinitrogen complexes are known, some of which contain largely
or exclusively amido ligands.7-13 Second, the coordination site
in [(RNCH2CH2)3N]V complexes contains two orthogonal π
orbitals and a σ orbital pointing along the z axis, a circumstance
that would seem to be optimal for binding dinitrogen in an “end-
on” fashion. Third, we recently reported several triamidoamine
complexes of molybdenum, including two that contain dinitro-
gen.14 One of them was proposed to be paramagnetic {[(C6F5-
NCH2CH2)3N]Mo}2(N2), an analog of structurally characterized
{[(t-BuMe2SiNCH2CH2)3N]Mo}2(N2).15 The other was pro-
NdNsNa, judging from its reaction with i-Pr3SiCl to give
structurally characterized diamagnetic [(C6F5NCH2CH2)3N]-
MosNdNsSi(i-Pr)3. Therefore, we became interested in the
possibility that trigonal-monopyramidal vanadium complexes
that contain the [(C6F5NCH2CH2)3N]3- ligand would be
more likely to bind dinitrogen than those that contain an
[(R3SiNCH2CH2)3N]3- ligand. In this paper we report the
preparation of several types of vanadium complexes that contain
the [(C6F5NCH2CH2)3N]3- ligand.
Results
Vanadium(V) Oxo and Arylimido Complexes. The
vanadium oxo complex [N3N]VdO (1; [N3N]3-
)
[(C6F5NCH2CH2)3N]3-) was prepared in ∼50% yield as orange
microcrystals by treating VOCl3 with H3[N3N] in cold dichlo-
romethane in the presence of Et3N (eq 1). This result is not
X Abstract published in AdVance ACS Abstracts, May 15, 1996.
(1) Plass, W.; Verkade, J. G. J. Am. Chem. Soc. 1992, 114, 2275.
(2) Cummins, C. C.; Schrock, R. R.; Davis, W. M. Organometallics 1992,
11, 1452.
(3) Cummins, C. C.; Lee, J.; Schrock, R. R. Angew. Chem., Int. Ed. Engl.
1992, 31, 1501.
(4) Plass, W.; Verkade, J. G. Inorg. Chem. 1993, 32, 3762.
(5) Cummins, C. C.; Schrock, R. R.; Davis, W. M. Inorg. Chem. 1994,
33, 1448.
(6) Hill, P. L.; Yap, G. A.; Rheingold, A. L.; Maatta, E. A. J. Chem.
Soc., Chem. Commun. 1995, 737.
(7) Woitha, C.; Rehder, D. Angew. Chem., Int. Ed. Engl. 1990, 29, 1438.
(8) Leigh, G. J.; Prietoalcon, R.; Sanders, J. R. J. Chem. Soc., Chem.
Commun. 1991, 921.
(9) Rehder, D.; Woitha, C.; Priebsch, W.; Gailus, H. J. Chem. Soc., Chem.
Commun. 1992, 364.
(10) Ferguson, R.; Solari, E.; Floriani, C.; Chiesi-Villa, A.; Rizzoli, C.
Angew. Chem., Int. Ed. Engl. 1993, 32, 396.
(11) Buijink, J.-K. F.; Meetsma, A.; Teuben, J. H. Organometallics 1993,
12, 2004.
(12) Berno, P.; Hao, S.; Minhas, R.; Gambarotta, S. J. Am. Chem. Soc.
1994, 116, 7417.
surprising in view of the prevalence of the oxo ligand in V(5+)
(14) Kol, M.; Schrock, R. R.; Kempe, R.; Davis, W. M. J. Am. Chem.
Soc. 1994, 116, 4382.
(13) Song, J.-I.; Berno, P.; Gambarotta, S. J. Am. Chem. Soc. 1994, 116,
6927.
(15) Shih, K.-Y.; Schrock, R. R.; Kempe, R. J. Am. Chem. Soc. 1994, 116,
8804.
S0020-1669(95)01433-9 CCC: $12.00 © 1996 American Chemical Society

3696 Inorganic Chemistry, Vol. 35, No. 12, 1996
Nomura and Schrock
chemistry and the synthesis of an analogous complex containing
the [(Me3SiNCH2CH2)3N]3- ligand.4,5 All data suggest that this
3-fold symmetric diamagnetic compound is a monomer in
solution. Since the oxo ligand is almost certainly pseudo triply
bound to the metal,4 1 can be viewed as an 18-electron complex.
(Only two of the possible three nitrogen p orbitals that lie in
the VN3 “plane” can form a π bond to the metal.) The VdO
stretch cannot be located with certainty in the IR spectrum
because of the presence of strong CF absorptions in the same
region. The 19F NMR spectrum of 1 shows three sharp
resonances for the ortho (-149.85, d, 6), meta (-164.86, t, 6),
and para (-163.07, t, 3) fluorines in a region that we now regard
as characteristic of diamagnetic species that contain this ligand.
(Resonances for the free ligand are found at -160.54 (6),
-164.61 (6), and -171.62 (3) ppm.14) Fluorine resonances in
paramagnetic complexes containing the [(C6F5NCH2CH2)3N]3-
ligand (see below) are sometimes also found in this region of
the 19F NMR spectrum, but they are relatively broad and easily
distinguished from those for diamagnetic species.
smoothly in good yield (70% yield after 2 days) in refluxing
mesitylene (162-164 °C). The two mechanisms for this
reaction for which there is precedent in the literature are the
“ureato mechanism” and the “metathesis mechanism” (eqs 5a
and 5b, respectively). Isolated monomeric ureato complexes
are relatively new,19-25 although bridging ureato complexes have
been known for some time.26 Addition of an aryl isocyanate
to an oxo species gives an imido species via a similar VOCN
metallacycle, presumably the intermediate in this analogous,
well-known reaction. The “metathesis mechanism”27-29 is less
well-known, although the vanadium-catalyzed condensation of
aryl isocyanates to N,N′-carbodiimides almost certainly involves
formation of this type of metallacycle.18 In view of this
precedent, the demonstrated reaction between [N3N]VdO and
arylisocyanates,17 and the catalytic formation of PhNdCdNPh
from PhNCO, we at present assume that the reaction proceeds
slowly as shown in eq 5b followed by the subsequent relatiVely
rapid reaction of [N3N]VdO with an aryl isocyanate.
Arylimido complexes, [N3N]VdNAr (2a-c; Ar ) p-MeC6H4,
p-CF3C6H4, p-FC6H4), could be prepared in high yields (∼80%)
from the known V(NAr)Cl3(THF) complexes16 in a similar
manner (eq 2). Although [N3N]VdNPh (2d) could not be
prepared and isolated in pure form in this manner, it could be
prepared in high yield from 1 as shown in eq 3, a type of
V(NAr)Cl3(THF) + H3[N3N] THF, 3Et N8 [N3N]VdNAr (2)
3
-3Et3NHCl
2a-c
Synthesis and Reactions of Vanadium(III) Complexes. A
“monopyramidal” [N3N]V complex analogous to those prepared
with silylated TREN ligands3 was one of our primary goals.
The most straightforward approach would seem to be the
reaction between VCl3(THF)3 and H3[N3N] in the presence of
triethylamine. When this reaction was carried out in diethyl
ether, a complex mixture resulted, according to 19F NMR
spectra. However, one of the components could be isolated in
∼50% yield as golden needles (eq 6) by multistep recrystalli-
Ar ) p-MeC6H4 (2a), p-CF3C6H4 (2b), p-FC6H4 (2c)
PhNCO (excess)
[N3N]VdO m-xylene, reflux, -CO 8
[N N]VdNPh
(3)
3
2
2d
reaction that is often used for preparing imido complexes.17 This
reaction is slow; therefore, it must be carried out in refluxing
m-xylene in the presence of an excess of aryl isocyanate. (There
was essentially no reaction in refluxing toluene after 1 day in
the presence of 1 equiv of PhNCO.) Other imido complexes
(2a, 2c, 2e (Ar ) o-FC6H4), 2f (Ar ) o-MeC6H4), and 2g (Ar
) 3,5-Me2C6H3)) also could be prepared by some version of
the reaction shown in eq 3. [N3N]VdN(aryl) complexes are
extremely stable thermally. They show no sign of decomposi-
tion after being heated in refluxing m-xylene (138 °C) for several
days. Attempts to prepare [N3N]VdNMe or [N3N]VdNH by
treating 1 with excess (Me3Si)2NMe or (Me3Si)2NH were
unsuccessful, even in refluxing m-xylene; 1 was simply
recovered quantitatively.
The reaction shown in eq 3 produced a new organic product
slowly (∼20 of 40 equiv consumed in 3 days) that by GC/MS
showed a parent ion consistent with it being PhNdCdNPh. This
type of catalytic reaction (2 (aryl)NCO yielding CO2 and
(aryl)NdCdN(aryl)) has been reported recently to be catalyzed
by V(V) oxo and imido species.18 This result encouraged us
to try to prepare one imido complex by treating another with
an aryl isocyanate. The reaction shown in eq 4 in fact proceeds
VCl3(THF)3 + H3[N3N] 3Et N/ether8
3
[HNEt3]+{[N3N]VCl}-
-2Et3NHCl
3
(6)
zation from mixtures of ether and dichloromethane. The proton
NMR spectrum of 3 showed two broad resonances at 0.30 and
1.86 ppm that we ascribe to the ethyl group of the ammonium
salt, while the 19F NMR spectrum showed two broad resonances
(18) Birdwhistell, K. R.; Boucher, T.; Ensminger, M.; Harris, S.; Johnson,
M.; Toporek, S. Organometallics 1993, 12, 1023.
(19) Michelman, R. I.; Andersen, R. A.; Bergman, R. G. J. Am. Chem.
Soc. 1991, 113, 5100.
(20) Hasselbring, R.; Roesky, H. W.; Noltemeyer, M. Angew. Chem., Int.
Ed. Engl. 1992, 31, 601.
(21) Herrmann, W. A.; Weichselbaumer, G.; Paciello, R. A.; Fischer, R.
A.; Herdtweck, E.; Okuda, J.; Marz, D. W. Organometallics 1990, 9,
489.
(22) Legzdins, P.; Phillips, E. C.; Rettig, S. J.; Trotter, J.; Veltheer, J. E.;
Yee, V. C. Organometallics 1992, 11, 3104.
(23) Lueng, W.-H.; Wilkinson, G.; Hussain-Bates, B.; Hursthouse, M. B.
J. Chem. Soc., Dalton Trans. 1991, 2791.
(24) Atagi, L. M.; Mayer, J. M. Organometallics 1994, 13, 4794.
(25) Coffey, T. A.; Forster, G. D.; Hogarth, G. J. Chem. Soc., Dalton. Trans.
1995, 2337.
p-FC6H4NCO (excess)
[N N]VdN(p-FC H )
2a or 2d mesitylene, reflux, 2 days8
(4)
3
6
4
2c
(26) Braunstein, P.; Nobel, D. Chem. ReV. 1989, 89, 1927.
(27) Green, M. L. H.; Hogarth, G.; Konidaris, P. C.; Mountford, P. J. Chem.
Soc., Dalton Trans. 1990, 3781.
(28) Hogarth, G.; Konidaris, P. C. J. Organomet. Chem. 1990, 399, 149.
(29) Forster, G. D.; Hogarth, G. J. Chem. Soc., Dalton Trans. 1993, 2539.
(16) Devore, D. D.; Lichtenhan, J. D.; Takusagawa, F.; Maata, E. A. J.
Am. Chem. Soc. 1987, 109, 7408.
(17) Wigley, D. E. Prog. Inorg. Chem. 1994, 42, 2239.

Vanadium Complexes Containing [(C6F5NCH2CH2)3N]3-
Inorganic Chemistry, Vol. 35, No. 12, 1996 3697
the V-N(1) distance is longer in 4a. The V-N(1)-Cipso angles,
a measure of the size of the 3-fold cavity, are virtually the same
for the two compounds. The V-N(5) distance in 4a is about
what would be expected for a donor nitrogen to vanadium bond.
An attempt to prepare the iodo analog of 3 by adding Me3-
SiI in THF to it yielded green crystalline [N3N]V(THF) (5; eq
7). [N3N]V(THF) is an exceedingly sensitive compound that
[HNEt3]{[N3N]VCl} +
THF
Me3SiI
8 [N3N]V(THF) (7)
-Et3NH+I-, -Me3SiCl
5
reacts instantly with acetonitrile to give 4a, with propylene oxide
to give [N3N]VdO, or with ethyl diazoacetate to give
[N3N]VdNNdCH(CO2Et) (see below). An X-ray structure of
5 (Figure 2, Tables 1 and 2) shows it to contain 1 equiv of
THF coordinated in the axial position with a rather long V-O(1)
distance of 2.152 Å. The long V-O(1) distance accounts for
the lability of the THF molecule and the consequent high
sensitivity and reactivity of 5. In contrast, nitrile ligands (as in
4a) experience relatively little steric pressure to dissociate from
the axial coordination position. The remainder of the structure
of 5 is similar to the structure of 4a and deserves little additional
comment.
The reaction between VCl3(THF)3 and the parent ligand in
the presence of tert-butyl isocyanide gave complex 6 (eq 8) as
Figure 1. Two Chem 3D views of the structure of [(C6F5NCH2-
CH2)3N]V(CH3CtN) (4a).
ether/t-BuNC/3Et3N
[N N]V(t-BuNC)
VCl3(THF)3 + H3[N3N]
8
3
-3Et3NHCl
at -141.9 (∆1/2 ) 508 Hz) and -176.8 ppm (∆1/2 ) 170 Hz)
in a 2:1 ratio that we ascribe to meta and para fluorines on the
aryl ring. We presume that resonances ascribable to the ortho
fluorines in the 19F NMR spectrum are too broad to be observed,
as they are the closest to the high-spin d2 center. An N-H
stretch characteristic of [HNEt3]+ also can be observed in the
IR spectrum.
6
(8)
green microcrystals. A proton NMR spectrum of 6 showed a
broad resonance at 4.35 ppm (∆1/2 ) 190 Hz) due to the tert-
butyl group. Two broad resonances ascribable to the [N3N]
ligand were observed in the 19F NMR spectrum at -148.5 ppm
(∆1/2 ) 280 Hz) and -170.2 ppm (∆1/2 ) 60 Hz) in a ratio of
2:1, while the IR spectrum showed a strong absorption band
due to the isocyanide group at 2180 cm-1. These data are all
consistent with the formation of a high-spin d2 vanadium(III)
isocyanide complex with a structure analogous to that found
for the nitrile and THF adducts.
When the reaction shown in eq 6 is carried out in the presence
of acetonitrile, then [N3N]V(CH3CN) (4a) could be isolated in
good yield. 4a was obtained as lime green microcrystals by
multistep extractions with ether and recrystallized from CH3-
CN layered with pentane at -30 °C. The 19F NMR spectrum
showed two broad resonances ascribable to meta (-146.3 ppm,
∆1/2 ) 340 Hz) and para (-175.7 ppm, ∆1/2 ) 113 Hz) fluorines
Addition of excess (trimethylsilyl)diazomethane to 4a gave
the imido-like diazo complex [N3N]VdNNdCH(SiMe3) (7a;
eq 9) in high yield (82%) as brick red microcrystals. The
in a ratio of 2:1; the ortho fluorine resonance again could not
be observed. The analytical sample appeared to contain two
molecules of acetonitrile, although the X-ray structure (see
below) showed that only one is present and is coordinated to
the metal. 4a also could also be prepared by recrystallizing 3
from a mixture of acetonitrile and ether. What we presume to
be analogous adducts that contain Me2CHCH2CtN (4b) or
CH2dCHCN (4c) were prepared by similar methods. The
reaction between 4a and propylene oxide at -30 °C gave 1 in
91% yield, but 4a failed to react with carbon monoxide,
ethylene, acetylene, phenylacetylene, pyridine, or trimethylsilyl
azide in toluene at 25 °C over periods of time varying from 2
to 10 days.
toluene
[N N]V(CH CN)
+ N2CH(SiMe3) -30 to 25 °C, 3 h8
3
3
4a
[N3N]VdNNdCH(SiMe3)
(9)
7a
diazoalkane ligand’s CH group is characterized by resonances
at 7.18 ppm in its H NMR spectrum and -170.2 ppm in its
1
13C NMR spectrum, consistent with the view that the carbon is
sp2-hybridized and imine-like. Like related imido complexes
mentioned earlier, 7a is extremely stable thermally, no change
being observed after 1 week in refluxing xylene. 7a could be
prepared from 3 in the same manner. An attempt to convert
7a into [N3N]VdCH(SiMe3) by heating it in the presence of
CuCl or tris(hexafluoroacetylacetonato)copper failed; no reaction
was observed. A similar complex, [N3N]VdNNdCH(CO2C2H5)
(7b), was also prepared in high yield (81%) as brick red
microcrystals from 4a. Compounds similar to 7a and 7b have
The X-ray structure of 4a shows it to be a trigonal-
bipyramidal species with acetonitrile coordinated in the apical
position (Figure 1, Tables 1 and 2). The compound whose
structure could be compared with 4a is the d1 species [(Me3-
SiNCH2CH2)3N]VCl;2 selected distances and angles for this
species are also listed in Table 1. There are several slight
differences between the structures of 4a and [(Me3SiNCH2-
CH2)3N]VCl. The Laxial-V-N(1) angle is larger and the
V-N(4) distance is longer in [(Me3SiNCH2CH2)3N]VCl, but

3698 Inorganic Chemistry, Vol. 35, No. 12, 1996
Nomura and Schrock
Table 1. Selected Distances (Å) and Angles (deg) in [N3N]V(CH3CtN) (4a), [N3N]V(C4H8O) (5), and [(Me3SiNCH2CH2)3N]VCla
4a
5
[(Me3SiNCH2CH2)3N]VCl
Distances
V-N(5)
2.081 (6)
1.941(3)b
2.149(5)
1.150(8)
V-O(1)
V-N(1)
V-N(2)
V-N(3)
V-N(4)
O(1)-C(1)
2.152 (3)
1.968(3)
1.958(3)
1.946(3)
2.132(3)
1.445(4)
V-Cl
V-N(1)
V-N(4)
2.278 (2)
1.883(6)
2.238(6)
V-N(1,2,3)
V-N(4)
N(5)-C(7)
Angles
N(5)-V-N(1)
N(1)-V-N(4)
V-N(1)-C(1)
N(5)-V-N(4)
V-N(1)-C(10)
N(1)-V-N(2)
96.88(9)
83.12(9)
128.2(2)
180b
O(1)-V-N(1)
N(1)-V-N(4)
V-N(1)-C(11)
O(1)-V-N(4)
V-N(1)-C(17)
N(1)-V-N(2)
92.34(11)
82.33(12)
131.5(2)
169.74(11)
114.4(2)
Cl-V-N(1)
100.0(2)
80.2(2)
126.1(3)
179.4(2)
113.6(5)
120.4(3)
N(1)-V-N(4)
V-N(1)-Si(1)
Cl-V-N(4)
112.7(2)
V-N(1)-C(1)
N(1)-V-N(2)
120b
119.79(13)
a See reference 1. b Defined crystallographically.
Table 2. Summary of Crystallographic Data, Collection
Parameters, and Refinement Parameters
Table 3. Observed Magnetic Moments for Several Vanadium(3+)
and Vanadium(4+) Complexes
a
a
[N3N]V(CH3CtN) (4a)
[N3N]V(THF) (5)
µobs
,
µB
µobs
,
µB
complex
complex
empirical formula
fw
a, Å
b, Å
C26H15N5F15V
733.36
13.021(1)
13.021(1)
14.221(1)
90
C28H20N4F15OV
764.42
15.390(7)
12.189(6)
16.468(7)
109.96(3)
90
2904(2)
P21/n
4
1.749
-86 ( 1
4.71
0.0625
0.1734
1.010
[N3N]V(t-BuNC)
3.3
3.4
3.4
3.5
[N3N]V(CH2dCHCN)
[N3N]V(THF)
[N3N]VCl
3.6
3.7
1.9
[N3N]V(Me2CHCH2CN)
[HNEt3]{[N3N]VCl}
[N3N]V(MeCN)
c, Å
â, deg
a Measured using the Evan's method with Me3SiOSiMe3 as an
indicator.
γ, deg
120
V, Å3
2088.2(5)
R3 (h)
3
1.749
-86 ( 1
4.69
0.043
0.040
1.48
space group
Z
observed in the 19F NMR spectrum of 8. We assign the fluorine
resonances to ortho, meta, and para fluorines, respectively, in
the pentafluorophenyl groups. The magnetic moment of 8 is
consistent with it being a d1 species, as shown in Table 3, in
contrast to the magnetic moments observed for the closely
analogous d2 species discussed so far.
F(calc), g/cm3
collecn temp, °C
µ(Mo KR), cm-1
Ra
b
Rw
goodness of fitc
Reduction of 8 with sodium amalgam in tetrahydrofuran under
dinitrogen over a period of 12 h at room temperature yielded
green microcrystals of 5 (eq 11). We rationalize that 5 is formed
2
a R ) ∑||Fo| - |Fc||/∑|Fo|. b Rw ) [(∑w(|Fo| - |Fc|)2/∑wFo )]1/2
.
c GOF ) [(∑w(|Fo| - |Fc|)2/(n - m)]1/2
.
Na amalgam
[N3N]VCl
[N N]V(THF)
8
(11)
3
THF
8
5
under these conditions rather than a sodium salt analogous to 3
because highly insoluble sodium chloride can be formed in this
case. Recent results suggest that reduction of 8 with sodium
amalgam in a noncoordinating solvent yields trigonal-monopy-
ramidal [N3N]V, even under dinitrogen.30 These results await
confirmation via an X-ray study.
Conclusions
Figure 2. Chem 3D drawing of the structure of [(C6F5NCH2CH2)3N]V-
(THF) (5).
The results reported here suggest that [(C6F5NCH2CH2)3N]3-
complexes of vanadium can be formed readily and that some
of them, especially “18-electron” V(5+) complexes, are remark-
ably stable thermally. Attempts to prepare trigonal-monopy-
ramidal V(3+) complexes yielded solvent or chloride adducts,
presumably because the metal is more electrophilic in
[(C6F5NCH2CH2)3N]3- complexes than in [(R3SiNCH2CH2)3N]3-
complexes and because dinitrogen cannot compete with σ donors
in binding to d2 vanadium centers in complexes of this type
under the conditions employed so far. At this stage it is
unknown whether dinitrogen will bind to vanadium, even if a
“trigonal-monopyramidal” species that contains a vacant coor-
dination position is prepared, although preliminary results30
suggest that it may not.
been isolated from reactions between (for example) [(Me3-
SiNCH2CH2)3N]V and diazoalkanes such as N2CH(SiMe3).5
Addition of ferrocenium triflate to 3 afforded [N3N]VCl (8)
in high yield (95%) as black microcrystals (eq 10). Two broad
FcOTf, CH2Cl2
[HNEt3]+{[N3N]VCl}-
[N N]VCl
8
(10)
3
-30 °C
8
3
[N3N] methylene proton resonances at -11.5 ppm (∆1/2 ) 300
Hz) and -68.5 ppm (∆1/2 ) 800 Hz)) were observed in the
proton NMR spectrum of 8, while three broad resonances at
-146.50 ppm (∆1/2 ) 180 Hz), -152.74 ppm (∆1/2 ) 45 Hz),
and -171.99 ppm (∆1/2 ) 80 Hz) in a ratio of 2:2:1 could be
(30) Rosenberger, C. Unpublished results.

Vanadium Complexes Containing [(C6F5NCH2CH2)3N]3-
Inorganic Chemistry, Vol. 35, No. 12, 1996 3699
mL). The red-yellow extract was concentrated to 10-15 mL in vacuo
and chilled to -30 °C overnight. The solution was decanted away
from the yellow needles, and the needles were washed quickly with
cold pentane and dried in vacuo (first crop 746 mg; second crop 220
mg; third crop 25 mg); total yield 991 mg (80%). The sample for
elemental analysis was prepared by recrystallization from a mixture of
toluene and ether.
Experimental Section
General Procedure. All experiments were carried out under a
nitrogen atmosphere in a Vacuum Atmospheres drybox or using
standard Schlenk techniques, unless otherwise specified. All chemicals
used were reagent grade and were purified by standard procedures.
Pentane was washed with sulfuric/nitric acid (95/5 v/v), sodium
bicarbonate, and then water, stored over calcium chloride, and then
distilled from sodium benzophenone ketyl under N2. Reagent grade
diethyl ether and tetrahydrofuran were distilled from sodium benzophe-
none ketyl under nitrogen. Toluene, m-xylene, and mesitylene were
distilled from sodium; CH2Cl2 and DMSO (dimethyl sulfoxide) were
distilled from CaH2. VCl4(dme),31 VCl3(THF)3,31 V(N(aryl))Cl3(THF),16
and 2,2′,2′′-tris((pentafluorophenyl)amino)triethylamine14 were prepared
by published methods. VOCl3, VCl3, VBr3, VCl4, aryl isocyanates,
propylene oxide, and trimethylsilyl iodide were purchased from
commercial sources and used as received. Acetonitrile, acrylonitrile,
and isovaleronitrile were passed through a column of activated alumina
in a drybox and stored over molecular sieves or distilled from CaH2.
All deuterated NMR solvents were passed through a column of activated
alumina in a drybox and stored over molecular sieves.
(ii) From [N3N]VdO. The preparation was carried out in a 100
mL Schlenk tube. Compound 1 (250 mg, 0.35 mmol), p-tolyl
isocyanate (2.0 g), and toluene (20 mL) were placed in a Schlenk tube,
and the solution was refluxed for 3 days under an atmosphere of
dinitrogen. The reaction solution was cooled and filtered through Celite.
The filtrate was concentrated to 2 mL. Ether (10 mL) was added to
the residue, and the solution was chilled to -30 °C. The yellow
microcrystals were collected, washed quickly with cold pentane, and
dried in vacuo; yield 80 mg. The solution was concentrated to 2 mL,
and pentane (10 mL) was added to give a second crop (80 mg). A
third crop was obtained from a mixture of toluene and pentane; total
yield 71%: 1H NMR (CDCl3) δ 6.62 (d, 2, J ) 8.9), 5.76 (d, 2, J )
8.3), 3.92 (t, 6, J ≈ 5.5), 3.31 (t, 6, J ≈ 5.5), 2.16 (s, 3, Me); 1H NMR
(C6D6) δ 6.24 (d, 2, J ) 9.0), 6.03 (d, 2, J ) 8.4), 3.42 (t, 6, J ≈ 5.5),
2.34 (t, 6, J ≈ 5.5), 1.66 (s, 3, Me); 19F NMR (CDCl3) δ -150.26 (br
s, 6), -165.88 (br s, 9); 19F NMR (C6D6) δ -150.22 (br s, 6), -165.55
(br s, 9). Anal. Calcd for C31H19F15N5V: C, 46.69; H, 2.40; N, 8.78.
Found: C, 46.56; H, 2.57; N, 8.66.
NMR operating frequencies and reference standards for heteronuclei
1
on the scale of H (300 MHz, SiMe4 at 0 ppm) are as follows: 13C
(75.5 MHz, SiMe4 at 0 ppm), and 19F (282.21 MHz, CFCl3 at 0 ppm).
Proton and carbon spectra were referenced using the partially deuterated
solvent as an internal reference. Fluorine NMR spectra were referenced
externally. Multiciplicities in fluorine spectra are quantified as “J”,
an apparent or pseudo coupling constant. Chemical shifts are in ppm,
and coupling constants and line widths are in hertz. All spectra were
acquired at ∼22 °C unless otherwise noted.
[N3N]VdN(p-CF3C6H4) (2b). 2b was prepared in the same manner
as 2a, except that V(N-p-CF3C6H4)Cl3(THF) (603 mg, 1.55 mmol) was
used in place of V(N-p-MeC6H4)Cl3(THF), and the reaction mixture
was stirred for 6 h. The brown-yellow extract was concentrated to 12
mL and chilled to -30 °C overnight. Orange-yellow needles of 2b
were collected, washed quickly with cold pentane, and dried in vacuo;
yield 490 mg. Further crops contained impurities which are difficult
to separate from 2b: 1H NMR (CDCl3) δ 7.12 (d, 2, J ) 8.9), 5.94 (d,
IR spectra were recorded on a Perkin-Elmer FT-IR 1600 spectrometer
as Nujol mulls between KBr plates in an airtight cell; all absorptions
are in cm-1. Microanalyses (C, H, N) were performed on a Perkin-
Elmer PE2400 microanalyzer. Magnetic moments were measured by
1H NMR (Evans method32 ) using Me3SiOSiMe3 as the indicator.
Preparations. [N3N]VdO (1). A cold (-30 °C) dichloromethane
solution (18 mL) of 2,2′,2′′-tris((pentafluorophenyl)amino)triethylamine
(H3[N3N]; 3.57 g, 5.57 mmol) and triethylamine (1.90 g, 18.8 mmol)
was added dropwise over a period of 1 h in several portions to a
dichloromethane solution (50 mL) containing VOCl3 (960 mg, 5.54
mmol) at -30 °C. The solution was warmed slowly to room
temperature and was stirred for more than 10 h. The solvents were
removed in vacuo, and the resulting orange-brown solid was extracted
with toluene (∼40 mL) and ether (∼20 mL) and then with a mixture
of ether and dme (150 mL). Solvents were removed from the ether/
dme solution in vacuo to give an analytically pure orange precipitate
(1.46 g). The solvents were removed from the orange-brown toluene
and ether extracts in vacuo. A minimum amount of dme was added to
the residue from the toluene extract and then ether to give a total volume
of ∼20 mL. Orange microcrystals were filtered from the chilled (-30
°C) solution, washed quickly with a small amount of cold pentane,
and dried in vacuo; yield 270 mg. The residue from the ether extract
produced another 340 mg for a total yield of 2.07 g (53%). 1 is soluble
in tetrahydrofuran, dichloromethane, dimethoxyethane, ether, and
toluene and slightly in pentane: 1H NMR (CDCl3) δ 3.94 (t, 6, J ≈
1
2, J ) 8.2), 3.96 (t, 6, J ≈ 5.5), 3.36 (t, 6, J ≈ 5.5); H NMR (C6D6)
6.65 (d, 2, J ) 8.4), 6.05 (d, 2, J ) 8.3), 3.37 (t, 6, J ≈ 5.5), 2.31 (t,
6, J ≈ 5.5); 19F NMR (CDCl3) δ -63.26 (s, 3, CF3), -150.06 (br m,
6), -164.50 (t, 3, “J” ) 24), -165.28 (t, 6, “J” ) 19); 19F NMR (C6D6)
δ -62.63 (s, 3, CF3), -150.26 (d, 6), -164.24 (t, 3, “J” ) 23), -165.01
(t, 6, “J” ) 19). Anal. Calcd for C31H16F18N5V: C, 43.73; H, 1.89;
N, 8.23. Found: C, 43.42; H, 2.06; N, 8.22.
[N3N]VdN(p-FC6H4) (2c). (i) From V(N-p-FC6H4)Cl3(THF). 2c
was prepared in the same manner as 2b except V(N-p-FC6H4)Cl3(THF)
(525 mg, 1.55 mmol) was used in place of V(N-p-MeC6H4)Cl3(THF);
total yield 980 mg (79%). The sample for elemental analysis was
prepared by recrystallization from a mixture of ether and pentane.
(ii) From [N3N]VdO. The preparation was performed in a 50 mL
Schlenk tube. A mixture of 1 (50 mg, 0.071 mmol) and p-fluorophenyl
isocyanate (1.0 g) in m-xylene (5.0 g) was added into a Schlenk tube,
and the solution was refluxed for 3 days under an atmosphere of
nitrogen. The reaction mixture was cooled and filtered through Celite.
The solvents were removed from the filtrate in vacuo. Toluene (0.5
mL), ether (5 mL), and pentane (5 mL) were added to the residue, and
the mixture was then chilled to -30 °C. The yellow microcrystals
were collected, washed quickly with cold pentane, and dried in vacuo
(32 mg). The second crop was isolated from the chilled mixture of
ether and pentane (10 mg); total yield 74%: 1H NMR (CDCl3) δ 6.53
(t, 2, J ) 8.6), 5.86 (dd, 2, J ) 8.7, 5.2), 3.94 (t, 6, J ≈ 5.5), 3.33 (t,
6, J ≈ 5.5); 1H NMR (C6D6) δ 6.01 (br s, 2), 5.98 (d, 2, J ) 2.5), 3.38
(t, 6, J ≈ 5.5), 2.31 (t, 6, J ≈ 5.5); 19F NMR (C6D6) δ -108.82 (t or
m, 1), -150.22 (d, 6, “J” ) 17), -164.88 (t, 3, “J” ) 22), -165.29 (t,
6, “J” ) 20). Anal. Calcd for C30H16F16N5V: C, 44.96; H, 2.01; N,
8.74. Found: C, 44.75; H, 2.33; N, 8.49.
[N3N]VdNPh (2d). A mixture of 1 (752 mg, 1.06 mmol) and
phenyl isocyanate (1.0 g) in m-xylene (5.0 g) was added to a 200 mL
Schlenk tube, and the solution was refluxed for 5 days under an
atmosphere of nitrogen. After the reaction, the solution was cooled
and filtered through Celite. The filtrate was concentrated to 20 mL in
vacuo, pentane (10-15 mL) was added, and the reaction mixture was
chilled to -30 °C. The yellow microcrystals were collected, washed
quickly with cold pentane, and dried in vacuo; yield 342 mg. The
yield was increased to 82% by using a mixture of toluene/ether, toluene/
ether/dme, or toluene/pentane: 1H NMR (C6D6) δ 6.43 (t, 2, J ) 7.5),
1
5.5), 3.24 (t, 6, J ≈ 5.5); H NMR (C6D6) δ 3.29 (t, 6, J ≈ 5.5), 2.12
(t, 6, J ≈ 5.5); 19F NMR (CDCl3) δ -149.85 (d, 6, “J” ) 17), -163.07
(t, 3, “J” ) 23), -164.86 (t, 6, “J” ) 20); 19F NMR (C6D6) δ -150.36
(d, 6), -162.00 (t, 3), -164.78 (t, 6). Anal. Calcd for C24H12F15N4-
OV: C, 40.69; H, 1.71; N, 7.91. Found: C, 40.60; H, 2.02; N, 7.69.
[N3N]VdN(p-MeC6H4) (2a). (i) From V(N-p-tol)Cl3(THF).
A
THF solution (8 mL) of H3[N3N] (1.0 g, 1.55 mmol) and triethylamine
(580 mg, 5.73 mmol) was added dropwise to a THF solution (10 mL)
containing V(N-p-tol)Cl3(THF) (519 mg, 1.55 mmol) at -30 °C. The
reaction mixture was then warmed slowly to room temperature and
was stirred for 5 h. The reaction mixture was filtered through Celite,
and the Celite was washed with toluene and ether until the filtrates
were colorless. The filtrates were combined, and the solvents were
removed in vacuo. The resulting solid was extracted with toluene (∼18
(31) Manzer, L. E. Inorg. Synth. 1982, 21, 135.
(32) Evans, D. F. Chem. Commun. 1959, 2003.

3700 Inorganic Chemistry, Vol. 35, No. 12, 1996
Nomura and Schrock
6.32 (t, 1, J ) 7.4), 6.15 (d, 2, J ) 7.7), 3.41 (t, 6, J ≈ 5.5), 2.37 (t,
6, J ≈ 5.5); 19F NMR (C6D6) δ -150.22 (d, 6, “J” ) 16), -165.22 (t,
3, “J” ) 22), -165.50 (t, 6, “J” ) 18).
was filtered through Celite and solvent was removed from the filtrate
in vacuo. The resulting lime green solid was extracted with cold ether,
and the ether was removed from the extract in vacuo. The residue
was dissolved in minimal acetonitrile, and this solution was covered
with pentane and chilled to -30 °C. The solution was decanted away
from the lime green microcrystals, which were washed quickly with
cold pentane and dried in vacuo; total yield 7.03 g (57%). The
compounds usually are pure enough for general use without recrystal-
lization. The sample for the X-ray study was recrystallized from
acetonitrile layered with pentane. The purification procedure was
repeated if white microcrystals were found mixed with the lime green
crystals.
[N3N]VdN(o-FC6H4) (2e). The preparation was the same as that
for 2c, except that o-fluorophenyl isocyanate (1.0 g) was used in place
of p-fluorophenyl isocyanate. The solvents were removed from the
extract in vacuo, and the residue was washed quickly with cold pentane.
The resulting yellow precipitate is pure enough for general use. Yellow
microcrystals were obtained from chilled ether (3-5 mL), washed
quickly with cold pentane, and dried in vacuo; yield 51 (91%): 1H
NMR (CDCl3) δ 6.73-6.80 (m, 1), 6.53-6.61 (m, 2), 5.96 (t, 1, J )
1
7.9), 3.94 (t, 6, J ≈ 5.5), 3.36 (t, 6, J ≈ 5.5); H NMR (C6D6) δ 6.24
+
-
(t, 1, J ) 7.7), 5.97-6.12 (m, 3), 3.40 (t, 6, J ≈ 5.5), 2.37 (t, 6, J ≈
5.5); 19F NMR δ -122.34 (s, 1), -150.53 (br s, or d, 6), -165.54 (t,
3, “J” ) 23), -166.28 (t, 6, “J” ) 20); 19F NMR (C6D6) δ -122.00
(s, 1), -150.11 (d, 6, “J” ) 15), -164.96 (t, 3, “J” ) 23), -165.71 (t,
6, “J” ) 21).
(ii) From [HNEt
3] {[N3N]VCl} (3). Golden needles of 3 (1.00
g) were partially dissolved in ether (30 mL), and to this mixture was
added an excess amount of acetonitrile (5 mL). The reaction mixture
was stirred for at least 3 h at room temperature, and the solvent was
removed from the reaction mixture in vacuo. The resulting lime green
solid was extracted with cold ether. The ether was removed from the
extract in vacuo, and the residue was dissolved in minimal acetonitrile.
The acetonitrile was then layered with pentane and chilled to -30 °C.
The solvent was decanted away from the lime green microcrystals,
which were washed quickly with cold pentane and dried in vacuo;
total from two crops 610 mg (65%): 1H NMR (C6D6) δ 0.60 (br s,
CH3CN, ∆1/2 ) 42); 19F NMR (C6D6) δ -146.3 (br s, ∆1/2 ) 340),
-175.7 (br s, ∆1/2 ) 113); IR (Nujol) 2281.6 cm-1 (CtN). Anal.
Calcd for C28H18F15N6V: C, 43.42; H, 2.34; N, 10.85. Found: C, 43.06;
H, 2.46; N, 10.37. According to this elemental analysis, this sample
contains two molecules of acetonitrile, although in the sample used
for the X-ray study one acetonitrile was found, and it was coordinated
to the vanadium.
Reaction of 4a with Propylene Oxide. Propylene oxide (30 mg)
was added dropwise to a solution of 4a (49 mg, 0.067 mmol) in 5 mL
of toluene at -30 °C. The reaction mixture was warmed slowly to
room temperature and was stirred for 3 h. The reaction solution was
filtered, and the solvents were removed from the filtrates in vacuo to
give an orange precipitate (41 mg). Proton and 19F NMR showed the
precipitate to be almost pure [N3N]VdO containing a trace of H3[N3N];
yield 91%.
[N3N]VdN(o-MeC6H4) (2f). The preparation of 2f was the same
as that for 2c except that o-tolyl isocyanate (1.0 g) was used in place
of p-fluorophenyl isocyanate. The solvents were partially removed from
the extract on a rotavaporator, and the yellow microcrystals were
collected, washed quickly with cold pentane, and dried in vacuo; yield
40 mg (71%): 1H NMR (CDCl3) δ 6.55-6.70 (m, 3), 5.81 (d, 1, J )
1
7.5), 3.92 (t, 6, J ) 5.6), 3.35 (t, 6, J ) 5.7), 1.40 (s, 3); H NMR
(C6D6) δ 6.24-6.60 (m, 3), 6.12 (d, 1, J ) 6.6), 3.40 (t, 6, J ) 5.7),
2.40 (t, 6, J ) 5.4), 1.39 (s, 3); 19F NMR (CDCl3) δ -150.00 (br d, 6),
-165.22 (t, 3, “J” ) 23), -165.97 (t, 6, “J” ) 20); 19F NMR (C6D6)
δ -149.76 (br s d, 6), -164.81 (t, 3, “J” ) 24), -165.55 (br t, 6).
[N3N]VdN(3,5-Me2C6H3) (2g). 2g was prepared in the same
manner as 2c using 3,5-dimethylphenyl isocyanate (1.0 g). The filtrate
was concentrated, ether and pentane were added, and the solution was
chilled to -30 °C for at least 2 days. The yellow microcrystals were
washed quickly with cold pentane and dried in vacuo; yield 27 mg
(47%): 1H NMR (CDCl3) δ 6.48 (br s, 1), 5.42 (br s, 2), 3.93 (t, 6, J
1
≈ 5.5), 3.31 (t, 6, J ≈ 5.5), 1.93 (s, 6); H NMR (C6D6) δ 6.13 (br s,
1), 5.78 (br s, 2), 3.42 (t, 6, J ≈ 5.5), 2.33 (t, 6, J ≈ 5.5), 1.77 (s, 6);
19F NMR (CDCl3) δ -150.46 (br s, 6), -166.47 (br s, 9); 19F NMR
(C6D6) δ -150.04 (br s or d, 6), -165.81 (br s, 9).
[N3N]V(Me2CHCH2CN) (4b). Preparation of 4b was similar to
that for 4a, using isovaleronitrile instead of acetonitrile; yield 3.40 g
(55%) of 4b from 2.96 g (7.92 mmol) of VCl3(THF)3 and 5.11 g (7.93
mmol) of H3[N3N]: 19F NMR (C6D6) δ -145.5 (br s, 6, ∆1/2 ) 400),
-176.0 (br s, 3, ∆1/2 ) 120); IR (Nujol) 2267.1 cm-1 (CtN). Anal.
Calcd for C29H21F15N5V: C, 44.91; H, 2.73; N, 9.03. Found: C, 44.58;
H, 2.76; N, 9.05.
Procedure for Reactions between [N3N]VdNAr and Various Aryl
Isocyanates. All reactions were carried out in a 50 mL Schlenk tube.
A mixture of [N3N]VdNAr (50 mg, Ar ) p-MeC6H4, Ph) and
p-fluorophenyl isocyanate (1.0 g) in mesitylene (5.0 g) was added to a
Schlenk tube, and the solution was refluxed for 2 days under an
atmosphere of nitrogen. The reaction mixture was cooled and filtered
1
through Celite. The crude reaction product was examined by H and
19F NMR in order to determine the extent of reaction. Isolated yields
of 2c from 2a or 2d were ∼70%.
[N3N]V(CH2dCHCN) (4c). A solution of H3[N3N] (1.01 g, 1.57
mmol) and triethylamine (600 mg, 5.94 mmol) in 5 mL of ether was
added gradually over a period of 1 h to an ether solution (10 mL)
containing VCl3(THF)3 (585 mg, 1.57 mmol) at -30 °C. Acrylonitrile
(1.0 g) was then added to the solution, and the reaction mixture was
warmed slowly to room temperature and was stirred for 1 day. The
reaction mixture was filtered through Celite, and solvents were removed
from the filtrate in vacuo. The green residue was extracted with ether,
and the extract was concentrated to ∼10 mL in vacuo and placed in a
freezer (-30 °C). The green microcrystals were washed quickly with
cold pentane and dried in vacuo. Analytically pure green microcrystals
of 4c were collected in one crop; yield 360 mg (31%): 19F NMR (C6D6)
δ -146.3 (br s, 6, ∆1/2 ) 350), -174.6 (br s, 3, ∆1/2 ) 125); IR (Nujol)
2235.7 (CtN), 1934.9, 1600 cm-1. Anal. Calcd for C27H15F15N5V:
C, 43.51; H, 2.03; N, 9.40. Found: C, 43.82; H, 1.83; N, 9.46.
[N3N]V(THF) (5). (i) From [HNEt3]+{[N3N]VCl}-. Trimethyl-
silyl iodide (92 mg, 1.05 equiv) was added dropwise over 5 min to a
stirred solution of 3 (364 mg, 0.439 mmol) in 10 mL of THF at room
temperature. After 3 h the solvents were removed in vacuo and the
residue was extracted with cold ether containing a few percent of
dichloromethane. The extract was cooled to -30 °C to give green
microcrystals, which were washed quickly with cold pentane and dried
in vacuo. The compounds were recrystallized from tetrahydrofuran
covered with pentane at -30 °C; yield 31% (105 mg): 19F NMR (C6D6)
δ -114.3 (br s, 6, ∆1/2 ) 260), -175.6 (br s, 3, ∆1/2 ) 120). Anal.
Calcd for C28H20F15N4OV: C, 44.00; H, 2.64; N, 7.33. Found: C,
44.13; H, 2.84; N, 7.34.
[HNEt3]+{[N3N]VCl}- (3). A solution of H3[N3N] (2.00 g, 3.10
mmol) and triethylamine (1.10 g, 10.9 mmol) in 18 mL of ether was
added gradually over a period of 1 h to a solution of VCl3(THF)3 (1.16
g, 3.10 mmol) in 50 mL of ether at -30 °C. The reaction mixture
was warmed slowly to room temperature and was stirred for 1 day.
The mixture was then filtered through Celite, and the filtrate was
concentrated to ∼35 mL and chilled to -30 °C for several days. Red-
purple microcrystals were collected, washed quickly with cold pentane,
and dried in vacuo; yield 1.66 g. These were dissolved in a minimum
amount of dichloromethane, and the solution was chilled to -30 °C
for several days. The solution was decanted away from the golden
needles, which were washed quickly with chilled ether and dried in
vacuo; yield 1.20 g (1.45 mmol, 47%). The product at this stage was
analytically pure. Samples from two different runs were both analyzed
satisfactorily: 1H NMR (C6D6) δ 1.86 (br s, 2, ∆1/2 ) 160), 0.30 (br s,
3, ∆1/2 ) 114); 19F NMR (C6D6) δ -141.9 (br s, 6, ∆1/2 ) 508), -176.8
(br s, 3, ∆1/2 ) 170); IR (Nujol) 2771.8, 2720.7, 2690.0, 2614.4, 2484.1
cm-1 (HNEt3+). Anal. Calcd for C30H28ClF15N5V: C, 43.41; H, 3.40;
N, 8.44. Found: C, 43.56, 43.27; H, 3.57, 3.47; N, 8.27, 8.29.
[N3N]V(CH3CN) (4a). (i) From VCl3(THF)3. An ether solution
(30 mL) of H3[N3N] (10.35 g, 16.1 mmol) and triethylamine (6.00 g,
59.4 mmol) was added gradually over 1 h to a solution of VCl3(THF)3
(1.74 g, 4.66 mmol) in 40 mL of ether at -30 °C. Acetonitrile (10
mL) was then added to the solution, and the reaction mixture was
warmed slowly to room temperature. After 1 day the reaction mixture

Vanadium Complexes Containing [(C6F5NCH2CH2)3N]3-
Inorganic Chemistry, Vol. 35, No. 12, 1996 3701
(ii) From [N3N]VCl. Sodium amalgam (4.02 g, Na/Hg ) 0.554/
104.55 g) was added dropwise to a solution of [N3N]VCl (664 mg,
0.912 mmol; see below) in 15 mL of tetrahydrofuran at room
temperature. The reaction mixture was stirred for 12 h and filtered
through Celite. The filtrate was evaporated in vacuo, and the residue
was extracted with cold ether. THF (2 mL) was added, and the solution
was then concentrated to ∼2 mL and covered with pentane (10 mL).
Analytically pure green microcrystals of 5 (380 mg) were collected
upon chilling the solution to -30 °C. A second crop (165 mg) was
obtained by further similar manipulations; total yield 545 mg (78%).
The sample for X-ray crystallography was prepared by recrystallization
from chilled (-30 °C) tetrahydrofuran solution covered with pentane.
Reaction of 5 with Propylene Oxide. Propylene oxide (12 mg,
0.21 mmol) was added dropwise to a stirred solution of 5 (54 mg, 0.071
mmol) in ether at -30 °C. The color changed from yellow-green to
orange. The reaction mixture was stirred for 10 min and then filtered.
The solvents were removed from the filtrate in vacuo to give 51 mg of
1 (quantitative), according to proton and fluorine NMR.
Reaction of 5 with Acetonitrile. Acetonitrile (15 mg) was added
to a stirred solution of 5 (45 mg, 0.059 mmol) in ether at -30 °C. The
color changed from yellow-green to lime green immediately. The
reaction mixture was stirred for 10 min and then filtered. The solvents
were removed from the filtrate in vacuo to give 45 mg of 4a, according
to proton and fluorine NMR. The only other observable product was
a trace of free ligand.
Reaction of 5 with Ethyl Diazoacetate. Ethyl diazoacetate (10
mg, 0.088 mmol) was added dropwise to a stirred solution of 5 (50
mg, 0.065 mmol) in ether at -30 °C. The color changed from yellow-
green to red immediately. The reaction mixture was stirred for 10 min
and then filtered. The solvents were removed from the filtrate in vacuo
to give 52 mg of 7b (quantitative), according to proton and fluorine
NMR.
[N3N]V(t-BuNC) (6). An ether solution (8 mL) of H3[N3N] (2.00
g, 3.10 mmol) and triethylamine (1.15 g, 11.39 mmol) was added
dropwise over 1 h to an ether solution (10 mL) containing VCl3(THF)3
(1.16 g, 3.10 mmol) at -30 °C. tert-Butyl isocyanide (1.0 g) was then
added, and the reaction mixture was warmed slowly to room temper-
ature and was stirred for 1 day. The reaction mixture was filtered
through Celite, and solvents were removed from the filtrate in vacuo.
The resulting green solid was extracted with ether. The extract was
concentrated to ∼15 mL and placed in the freezer (-30 °C). The
solvent was decanted away from the green microcrystals, which were
washed quickly with cold pentane and dried in vacuo. Analytically
pure 6 was obtained in two crops; yield 750 mg (31%): 1H NMR (C6D6)
δ 4.35 (br s, ∆1/2 ) 190, CMe3); 19F NMR (C6D6) δ -148.5 (br s, ∆1/2
) 280), -170.2 (br s, ∆1/2 ) 60); IR (Nujol) 2180.5 cm-1 (NtC).
Anal. Calcd for C29H21F15N5V: C, 44.91; H, 2.73; N, 9.03. Found:
C, 45.29; H, 3.16; N, 9.00.
[N3N]VdNNdCH(SiMe3) (7a). (Trimethylsilyl)diazomethane (1.0
g, 2 M solution in hexane) was added dropwise over 5 min to 4a (500
mg, 0.65 mmol) in 10 mL of toluene at -30 °C. The reaction mixture
was warmed slowly to room temperature and was stirred for 3 h. The
solution was concentrated to ∼3 mL and then poured into a stirred
pentane solution (∼15 mL), which was then placed in the freezer at
-30 °C for 1 h. The red precipitate was filtered off, and the solvents
were removed from the filtrate in vacuo to afford 7a. The red solids
were dissolved in a minimum amount of toluene. The toluene solution
was covered with pentane, and the mixture was placed in the freezer
(-30 °C). Analytically pure red microcrystals of 7a were isolated,
washed quickly with cold pentane, and dried in vacuo; yield 427 mg
(82%): 1H NMR (C6D6) δ 7.18 (s, 1, NdCH), 3.42 (t, 6, J ≈ 5.5),
2.37 (t, 6, J ≈ 5.5), 0.20 (s, 9, CHSi(CH3)3); 13C NMR (C6D6) δ 176.70
(NdCH), 143.43, 140.24, 140.11, 138.95, 138.77, 138.65, 136.89,
136.63, 135.74, 135.59 (C6F5), 57.21, 54.01 (CH2); 19F NMR (C6D6) δ
-150.46 (d, 6, “J” ) 21), -165.75 (t, 6, “J” ) 26), -166.19 (t, 6, “J”
) 19). Anal. Calcd for C28H22F15N6SiV: C, 41.70; H, 2.75; N, 10.42.
Found: C, 41.80; H, 2.61; N, 10.37.
obtained; yield 710 mg (81%): 1H NMR (C6D6) δ 6.92 (s, 1, NdCH),
3.64 (q, 2, J ) 7.1, CH2CH3), 3.38 (t, 6, J ≈ 5.5), 2.39 (t, 6, J ≈ 5.5),
0.69 (t, 3, J ) 7.5, CH2CH3); 19F NMR (C6D6) δ -150.61 (d, 6, “J” )
37), -163.74 (t, 6, “J” ) 24), -164.81 (t, 6, “J” ) 29); IR (Nujol)
1731.5 (CdO). Anal. Calcd for C28H18F15N6O2V: C, 41.70; H, 2.25;
N, 10.42. Found: C, 41.89; H, 2.21; N, 10.24.
[N3N]VCl (8). Ferrocenyl trifluoromethanesulfonate (833 mg, 2.49
mmol) was added to a solution of 3 (1.80 g, 2.17 mmol) in
dichloromethane (50 mL) at -30 °C. The reaction mixture was warmed
slowly to room temperature and stirred for ∼20 h. The solution was
filtered through Celite, and the solvents were evaporated from the filtrate
in vacuo. The residue was dissolved in toluene (50 mL) and the solution
placed in the freezer (-30 °C) overnight. The black microcrystals were
isolated and dissolved in a minimum amount of dichloromethane. The
solution was chilled to -30 °C to give black microcrystals of 8, which
were washed with chilled toluene and dried in vacuo; yield 1.50 g
(95%). The analytical sample was prepared by recrystallization from
dichloromethane: 1H NMR (C6D6) δ -11.5 (br s, ∆1/2 ) 300), -68.5
(br s, ∆1/2 ) 800); 19F NMR (C6D6) δ -146.50 (br s, 6, ∆1/2 ) 180),
-152.74 (br s, 6, ∆1/2 ) 45), -171.99 (br s, 3, ∆1/2 ) 80). Anal.
Calcd for C24H12ClF15N4V: C, 39.61; H, 1.66; N, 7.70. Found: C,
39.69; H, 1.72; N, 7.76.
Brief Description of the Structure of [(C6F5NCH2CH2)3N]V-
(CH3CN). The crystal was mounted on a glass fiber and transferred
to an Enraf-Nonius CAD-4 diffractometer with graphite-monochromated
Mo KR radiation (λ ) 0.710 79 Å). Cell constants and an orientation
matrix for data collection obtained from 25 carefully centered reflections
in the range 14 < 2θ < 22.00° corresponded to a rhombohedral
(hexagonal axes) cell. On the basis of the systematic absences (hkl,
-h + k + l * 3n), packing considerations, a statistical analysis of
intensity distributions, and the successful solution and refinement of
the structure, the space group was determined to be R3 (h) (No. 146).
The data were collected using the ω-2θ scan technique to a maximum
2θ value of 54.9°.
Of the 3345 reflections which were collected, 2145 were unique
(Rint ) 0.073); equivalent reflections were merged. The structure was
solved by a combination of the Patterson method and direct methods.
Non-hydrogen atoms were refined anisotropically. The final cycle of
full-matrix least-squares refinement was based on 1775 observed
reflections (I > 3.00σ(I)) and 142 variable parameters and converged
(the largest parameter shift was 0.00 times its esd) with unweighted
and weighted agreement factors of R ) 0.043 and Rw ) 0.040.3
Brief Description of the Structure of [(C6F5NCH2CH2)3N]V-
(THF). The crystal was mounted under Paratone N and transferred to
a Siemens Smart/CCD three-circle (ø fixed at 54.78°) diffractometer
equipped with a cold stream of N2 gas. An initial unit cell was
determined by harvesting reflections I > 20σ(I) from 45 frames of 0.30
ω-scan data with monochromated Mo KR radiation (λ ) 0.710 73 Å).
Crystal quality was checked by computing 3.0° rocking curves, from
which the ω width at half-height was found to be 0.23°. The data
were collected using 0.30 ω scans. The data that were collected (10 147
total reflections, 4198 unique, Rint ) 0.044) were corrected for Lorentz
and polarization effects but not for absorption. The structure was solved
(SHELXTL 5.0) by direct methods and standard difference Fourier
techniques.
Acknowledgment. We thank the National Institutes of
Health (Grant No. GM 31978) and Sumitomo Chemical Co.
Ltd. for support. We also thank the National Science Founda-
tion for funds to help purchase a Siemens SMART/CCD
diffractometer and Steve Reid for experiments confirming the
catalytic production of PhNdCdNPh from PhNCO using
[N3N]VdO as a catalyst.
Supporting Information Available: For both 4a and 5, text giving
descriptions of the structures, ORTEP drawings, and tables of final
positional parameters, final thermal parameters, and bond distances and
angles for non-hydrogen atoms (13 pages). Ordering information is
given on any current masthead page.
[N3N]VdNNdCH(CO2C2H5) (7b). 7b was prepared in the same
manner as that for 7a using ethyl diazoacetate (500 mg) and 630 mg
(0.81 mmol) of 4a. Analytically pure red microcrystals of 7b were
IC951433J