Reduction of a coordinated acetonitrile ligand: Synthesis of an ethylimido complex of tungsten

Article abstract of DOI:10.1021/om970829v

Treatment of the dinitrogen complex W(N₂)₂(dppe)₂ (1; dppe = 1,2-bis(diphenylphosphino)-ethane) with trifluoromethanesulfonic acid yields the novel hydrazido complex [W(N₂H₂)-(OTf)(dppe)₂]⁺[OTf] ^- (2; OTf = CF₃SO₃^-). The triflato ligand is readily displaced by other ligands and coordinating solvents. The triflato complex 2 yields the complex [W(N₂H₂)-(NCCH₃)(dppe)₂] ²⁺ (5), when it is dissolved in acetonitrile, and 5 is readily deprotonated by a variety of bases to give the acetonitrile-dinitrogen complex W(N₂)(NCCH₃)(dppe)₂ (3). Complex 3 is protonated at the β-carbon by tetrafluoroboric acid, resulting in the reduction of the coordinated nitrile to give the novel imido complex [WF(NCH₂CH₃)(dppe)₂]⁺[BF ₄]^- (4). The X-ray crystal structure of the imido complex 4 reveals an effectively linear W-N-C bond (171.8°) in the imido ligand with a W-N bond length of 1.741(4) A?.

Full text of DOI:10.1021/om970829v

2394
Organometallics 1998, 17, 2394-2398
Articles
Red u ction of a Coor d in a ted Aceton itr ile Liga n d :
Syn th esis of a n Eth ylim id o Com p lex of Tu n gsten
Leslie D. Field,* Neale G. J ones, and Peter Turner
School of Chemistry, The University of Sydney, Sydney, Australia 2006
Received September 22, 1997
Treatment of the dinitrogen complex W(N2)2(dppe)2 (1; dppe ) 1,2-bis(diphenylphosphino)-
ethane) with trifluoromethanesulfonic acid yields the novel hydrazido complex [W(N2H2)-
(OTf)(dppe)2]+[OTf]- (2; OTf ) CF3SO3-). The triflato ligand is readily displaced by other
ligands and coordinating solvents. The triflato complex 2 yields the complex [W(N2H2)-
(NCCH3)(dppe)2]2+ (5), when it is dissolved in acetonitrile, and 5 is readily deprotonated by
a variety of bases to give the acetonitrile-dinitrogen complex W(N2)(NCCH3)(dppe)2 (3).
Complex 3 is protonated at the â-carbon by tetrafluoroboric acid, resulting in the reduction
of the coordinated nitrile to give the novel imido complex [WF(NCH2CH3)(dppe)2]+[BF4]-
(4). The X-ray crystal structure of the imido complex 4 reveals an effectively linear W-N-C
bond (171.8°) in the imido ligand with a W-N bond length of 1.741(4) Å.
In tr od u ction
prepared via a number of methods, including reactions
of metal complexes with isocyanates,8 deprotonation of
amine/amido ligands,9 and nucleophilic attack at the
â-carbon of nitrile ligands.10
In this paper we describe the synthesis of the complex
W(N2)(NCCH3)(dppe)2 (3; dppe ) 1,2-bis(diphenylphos-
phino)ethane), from W(N2)2(dppe)2 (1), by an indirect
route via the hydrazido complex [W(N2H2)(OTf)(dppe)2]+
(2; OTf ) CF3SO3-). Protonation of the acetonitrile
ligand affords a novel imido complex, [WF(NCH2CH3)-
(dppe)2]+ (4), effectively reducing the coordinated nitrile
(Scheme 1).
There has been considerable interest in the reduction
of small, unsaturated nitrogen-containing molecules at
molybdenum and tungsten dinitrogen binding centers.1
A range of hydrazido,2 aminocarbyne,3 and carbyne/
alkylidene4 complexes have been prepared via the
reduction of coordinated dinitrogen, isonitrile, and alky-
nyl ligands, respectively, under protic conditions. In
some systems, the NtN or CtN bond of the coordinated
dinitrogen or isonitrile ligand undergoes complete re-
ductive cleavage to yield free amines or alkanes.5
Although the products from the reductive cleavage of
nitriles have also been detected,6 no analogous imido
complexes derived from the â-protonation of coordinated
organonitriles have yet been reported.
(5) (a) Chatt, J .; Pearman, A. J .; Richards, R. L. Nature (London)
1975, 253, 39. (b) Chatt, J .; Pearman, A. J .; Richards, R. L. J . Chem.
Soc., Dalton Trans. 1977, 1852. (c) Takahashi, T.; Mizobe, Y.; Sato,
M.; Uchida, Y.; Hidai, M. J . Am. Chem. Soc. 1979, 101, 3405. (d) Ibid.
1980, 102, 7461. (e) Pombeiro, A. J . L.; Richards, R. L. Transition Met.
Chem. 1980, 5, 281. (f) Chatt, J .; Fakley, M. E.; Hitchcock, P. B.;
Richards, R. L.; Luong-Thi, N. T. J . Chem. Soc., Dalton Trans. 1982,
345. (g) Nishihara, H.; Mori, T.; Tsurita, Y.; Nakano, K.; Saito, T.;
Sasaki, Y. J . Am. Chem. Soc. 1982, 104, 4367. (h) Baumann, J . A.;
Bossard, G. E.; George, T. A.; Howell, D. B.; Koczon, L. M.; Lester, R.
K.; Noddings, C. M. Inorg. Chem. 1985, 24, 3568. (i) Pickett, C. J .;
Ryder, K. S.; Talarmin, J . J . Chem. Soc., Dalton Trans. 1986, 1453. (j)
Kaul, B. B.; Hayes, R. K.; George, T. A. J . Am. Chem. Soc. 1990, 112,
2002. (k) George, T. A.; Kaul, B. B. Inorg. Chem. 1990, 29, 4969. (l)
George, T. A.; Kaul, B. B. Inorg. Chem. 1991, 30, 883.
(6) (a) Pombeiro, A. J . L.; Silva, M. F. C. G.; Hughes, D. L.; Richards,
R. L. Polyhedron 1989, 8, 1872. (b) Carvalho, M. F. N. N.; Borrego, M.
F.; Pombeiro, A. J . L. XXVI Int. Conf. Coord. Chem. Porto 1988, Ms-
4/P4.
(7) See for example: Nugent, W. A.; Haymore, B. L. Coord. Chem.
Rev. 1980, 31, 123.
(8) (a) Bradley, D. C.; Hursthouse, M. B.; Abdul Malik, K. M.;
Nielson, A. J .; Short, R. L. J . Chem. Soc., Dalton Trans. 1983, 2651.
(b) Clark, G. R.; Glenny, M. W.; Nielson, A. J .; Rickard, C. E. F. J .
Chem. Soc., Dalton Trans. 1995, 1147. (c) Forster, G. D.; Hogarth, G.
J . Organomet. Chem. 1994, 471, 161.
(9) Powell, K. R.; Perez, P. J .; Luan, L.; Feng, S. G.; White, P. S.;
Brookhart, M.; Templeton, J . L. Organometallics 1994, 13, 1851.
(10) (a) Colquhoun, H. M.; Crease, A. E.; Taylor, S. A.; Williams, D.
J . J . Chem. Soc., Chem. Commun. 1982, 736. (b) Feng, S. G.; White,
P. S.; Templeton, J . L. J . Am. Chem. Soc. 1994, 116, 8613.
There has also been considerable work employing
transition-metal imido complexes7 as an important class
of compounds for stoichiometric and catalytic transfor-
mations. (Organoimido)tungsten complexes have been
(1) (a) Hidai, M. H.; Mizobe, Y. Chem. Rev. 1995, 95, 1115. (b)
Pombeiro, A. J . L.; Richards, R. L. Coord. Chem. Rev. 1990, 104, 13.
(c) Leigh, G. J . New J . Chem. 1994, 18, 157.
(2) (a) Chatt, J .; Heath, G. A.; Richards, R. L. J . Chem. Soc., Dalton
Trans. 1974, 2074. (b) Heath, G. A.; Mason, R.; Thomas, K. M. J . Am.
Chem. Soc. 1974, 96, 259. (c) Hidai, M.; Kodama, T.; Sato, M.;
Harakawa, M. Inorg. Chem. 1976, 15, 2694. (d) Chatt, J .; Pearman,
A. J .; Richards, R. L. J . Chem. Soc., Dalton Trans. 1978, 1766. (e) Abu
Bakar, M.; Hughes, D. L.; Hussain, W.; Leigh, G. J .; Macdonald, C. J .;
Mohd-Ali, H. J . Chem. Soc., Dalton Trans. 1988, 2545. (f) Barclay, J .
E.; Hills, A.; Hughes, D. L.; Leigh, G. J .; Macdonald, C. J .; Abu Baker,
M.; Mohd-Ali, H. J . Chem. Soc., Dalton Trans. 1990, 2503.
(3) (a) Chatt, J .; Pombeiro, A. J . L.; Richards, R. L. J . Chem. Soc.,
Dalton Trans. 1980, 492. (b) Chatt, J .; Pombeiro, A. J . L.; Richards,
R. L. J . Chem. Soc., Dalton Trans. 1979, 1585. (c) Chatt, J .; Pombeiro,
A. J . L.; Richards, R. L. J . Organomet. Chem. 1980, 184, 357. (d)
Pombeiro, A. J . L.; Richards, R. L. Transition Met. Chem. 1980, 5, 55.
(e) Pombeiro, A. J . L.; Richards, R. L. Inorg. Synth. 1985, 23, 9.
(4) (a) Hills, A.; Hughes, D. L.; Kashef, R. L.; Richards, R. L.; Lemos,
M. A. N. D. A.; Pombeiro, A. J . L. J . Organomet. Chem. 1988, 350, C4.
S0276-7333(97)00829-7 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 05/15/1998

An Ethylimido Complex of Tungsten
Organometallics, Vol. 17, No. 12, 1998 2395
Sch em e 1
Sch em e 2
Reaction of the dinitrogen complex 3 with tetrafluo-
roboric acid in benzene at room temperature resulted
in protonation at the â-carbon of the acetonitrile ligand
to yield the ethylimido complex [WF(NCH2CH3)-
(dppe)2]+[BF4]- (4), as an orange crystalline solid. The
reduction of the nitrile moiety was accompanied by a
formal four-electron oxidation of the W(0) center, result-
ing in the formation of a WtN triple bond.
The ethylimido complex 4 was fully characterized by
multinuclear NMR and X-ray crystallographic studies.
The 31P{1H} NMR spectrum of 4 exhibited a fluorine-
coupled doublet at δ 33.6 ppm (2J P-F ) 44.5 Hz) and
tungsten satellites (1J P-W ) 293.0 Hz). The single
resonance confirms that the phosphorus atoms occupy
the four equivalent equatorial coordination sites around
the tungsten atom. The 19F NMR spectrum exhibited
two signals. The low-field signal (δ -149.9 ppm)
appeared as a broad singlet and was assigned to the
tetrafluoroborate counterion. The high-field signal (δ
Resu lts a n d Discu ssion
A number of hydrazido complexes of the type [W-
(N2H2)X(dppe)2]+Y- (X ) Y ) Cl, Br, tosylate; X ) F, Y
) BF4)2a,c,5i,11 have been prepared from the reaction of
the bis(dinitrogen) complex W(N2)2(dppe)2 (1), with the
acid HY. The novel hydrazido complex [W(N2H2)-
(OTf)(dppe)2]+[OTf]- (2; OTf- ) CF3SO3-) was similarly
prepared from the reaction of 1 with trifluoromethane-
sulfonic acid in benzene (Scheme 1). The reaction
proceeded in moderate yield (64%) at room temperature
to give 2 as a light brown crystalline solid.
2
-174.8 ppm) appeared as a quintet with J P-F ) 44.5
Hz and was assigned to the metal-bound fluoro ligand.
In addition to the resonances of the dppe ligand, the
1H{31P} NMR spectrum exhibited a triplet at δ -0.30
The complex 2 exhibited a single peak in the 31P{1H}
NMR spectrum at δ 37.9 ppm with tungsten satellites
(1J W-P ) 284.5 Hz), indicating that the phosphorus
atoms were chemically equivalent and occupied the four
equatorial coordination sites. Apart from the reso-
3
ppm with J H-H ) 7.4 Hz and a doublet of quartets at
3
4
δ 1.91 ppm with J H-H ) 7.4 Hz and J H-F ) 3.7 Hz.
The high-field resonance collapsed to a singlet upon
selective decoupling of the resonance at δ 2.25 ppm and
was assigned to the CH3-group of the ethylimido
ligand. The resonance at δ 2.25 ppm was assigned to
the -CH2- group of the imido ligand. 13C NMR
confirmed the presence of a CH3CH2- moiety, exhibiting
a resonance for the CH3 group at δ 14.1 ppm and for
the CH2 group at δ 57.8 ppm.
1
nances of the dppe ligand, the H{31P} NMR spectrum
exhibited a broadened singlet at δ 5.11 ppm, which was
assigned to the protons on the hydrazido ligand. The
protons of the hydrazido ligand underwent rapid H/D
exchange in methanol-d4.
The presence of two distinct triflate environments,
one coordinated triflato ligand and one triflate counter-
ion, was confirmed by 19F NMR spectroscopy. The 19F
NMR spectrum consisted of two singlet resonances of
equal intensity, with the coordinated triflate (δ -73.1
ppm) appearing to slightly lower field than the coun-
terion (δ -75.2 ppm). The coordinated triflato ligand
was readily displaced in coordinating solvents such as
acetonitrile and methanol.
When the hydrazido complex 2 was dissolved in
acetonitrile, the triflato ligand was displaced to yield
the intermediate complex [W(N2H2)(NCCH3)(dppe)2]2+
(5). On treatment with base, (KOtBu, Et3N, or NaBH4/
EtOH), 5 was deprotonated to yield the dinitrogen-
acetonitrile complex W(N2)(NCCH3)(dppe)2 (3)12 in good
yield (76%) (Scheme 2).
X-ray crystallographic studies confirmed the structure
of complex 4. The complex adopts a slightly distorted
octahedral geometry about the tungsten center with the
tungsten displaced from the least-squares equatorial
plane by 0.18 Å toward the imido axial ligand (Figure
1).
Selected bond distances and angles are shown in
Table 1. The four phosphorus atoms occupy the equato-
rial coordination sites of the tungsten center and have
very similar bond lengths. The ethylimido and fluoro
ligands occupy the remaining axial coordination sites,
in a trans configuration.
The W(1)-N(1)-C(1) bond angle of 171.8° is es-
sentially linear and is typical of complexes containing
(12) This complex has previously been prepared using a photochemi-
cal approach: Leigh, G. J .; Pickett, C. J . J . Chem. Soc., Dalton Trans.
1977, 1797.
(11) Hidai, M.; Mizobe, Y.; Sato, M.; Kodama, T.; Uchida, Y. J . Am.
Chem. Soc. 1978, 100, 5740.

2396 Organometallics, Vol. 17, No. 12, 1998
Field et al.
result of disorder or high thermal motion and could
contribute to the apparently short C(1)-C(2) bond.
Although imido complexes of tungsten and molybde-
num have been synthesized by other methods,8-10 the
isolation and characterization of the ethylimido complex
4 represents the first example of the preparation of an
imido complex from the protic reduction of a nitrile
ligand. The analogous â-protonation of isoelectronic
ligands (dinitrogen,2 isonitriles,3 and acetylides4) at
metal centers has been well-established, and the prepa-
ration of complex 4 effectively completes this series.
The stepwise approach to the acetonitrile-dinitrogen
species 3 via the hydrazido complex 2 provides a
thermal route from the bis(dinitrogen) complex 1. The
protonation of one dinitrogen ligand permits substitu-
tion of the other. This approach is potentially applicable
to the synthesis of a wide variety of substituted hy-
drazido or dinitrogen complexes.
Su m m a r y
F igu r e 1. ORTEP diagram of [WF(NCH2CH3)(dppe)2]+-
[BF4]- (4), showing atom labeling (25% ellipsoids).
The hydrazido complex [W(N2H2)(OTf)(dppe)2]+[OTf]-
was synthesized by the protonation of the dinitrogen
complex W(N2)2(dppe)2 with trifluoromethanesulfonic
acid. Displacement of the triflato ligand and deproto-
nation of the hydrazido moiety afforded the acetonitrile
complex W(NCCH3)(N2)(dppe)2. Protonation of W(NC-
CH3)(N2)(dppe)2 with ethereal tetrafluoroboric acid pro-
ceeded at the nitrile carbon, resulting in the reduction
of the acetonitrile to an ethylimido ligand to give the
complex [WF(NCH2CH3)(dppe)2]+[BF4]- (4). The reduc-
tion was accompanied by a formal four-electron oxida-
tion of the tungsten center, resulting in the formation
of the tungsten-nitrogen triple bond.
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [WF (NCH2CH3)(d p p e)2]+[BF 4]- (4)
W(1)-N(1)
W(1)-P(1)
W(1)-P(3)
N(1)-C(1)
1.741(4)
2.511(1)
2.517(1)
1.456(7)
W(1)-F(1)
W(1)-P(2)
W(1)-P(4)
C(1)-C(2)
2.008(2)
2.519(1)
2.511(1)
1.28(1)
W(1)-N(1)-C(1)
N(1)-W(1)-P(1)
N(1)-W(1)-P(3)
P(1)-W(1)-F(1)
P(1)-W(1)-P(3)
P(2)-W(1)-F(1)
P(2)-W(1)-P(4)
P(3)-W(1)-P(4)
171.8(4)
87.2(1)
N(1)-W(1)-F(1)
N(1)-W(1)-P(2)
N(1)-W(1)-P(4)
P(1)-W(1)-P(2)
P(1)-W(1)-P(4)
P(2)-W(1)-P(3)
P(3)-W(1)-F(1)
P(4)-W(1)-F(1)
177.7(1)
91.5(1)
92.9(1)
79.66(4)
101.67(4)
99.74(4)
77.43(8)
85.56(8)
104.0(1)
91.35(8)
168.77(4)
90.10(8)
175.48(4)
78.10(4)
Exp er im en ta l Section
Ta ble 2. W-N Bon d Len gth s (Å) a n d W-N-R
Bon d An gles (d eg) of Selected Tu n gsten
Com p lexes (R ) C, N)
Gen er a l P r oced u r es. All manipulations were performed
under an inert atmosphere of nitrogen, either by use of
standard Schlenk and vacuum line techniques or by perform-
ing reactions in a nitrogen-filled drybox. All solvents were
degassed and distilled under a nitrogen atmosphere from a
suitable drying agent. W(N2)2(dppe)2 was synthesized by
following the method of Hussain et al.15 NMR spectra were
recorded using a Bruker AMX400 spectrometer and were
recorded at 300 K. 1H NMR (400.13 MHz) and 13C NMR
(100.61 MHz) chemical shifts were referenced to internal
solvent residuals. 31P NMR (161.98 MHz) NMR chemical
shifts were referenced to external, neat trimethyl phosphite,
taken as δ 140.85 ppm. 19F NMR (376.43 MHz) chemical shifts
were referenced to external, neat hexafluorobenzene, taken as
δ -163.0 ppm. Elemental analyses were performed at the
Australian National University Research School of Chemistry
(Canberra, Australia) and Campbell Microanalytical Labora-
tories, University of Otago (Dunedin, New Zealand).
Syn t h esis of tr a n s-Bis[1,2-b is(d ip h en ylp h osp h in o)-
et h a n e]h yd r a zid o(t r ifla t o)t u n gst en Tr ifla t e, [W(OTf)-
(N2H2)(d p p e)]+[OTf]- (2). Trifluoromethanesulfonic acid
(220 mg, 1.45 mmol) was added to a solution of W(N2)2(dppe)2
(1; 0.60 g, 580 µmol) in benzene (40 mL). The reaction mixture
was stirred at room temperature for 3 h, and the solvent was
removed in vacuo to give a brown oily residue. The residue
was dissolved in tetrahydrofuran (5 mL), and the addition of
complex
W-N
W-N-R
[W(N2H2)Cl(dppe)2]+[BPh4]- a
1.73(1)
171(1)
174(1)
[W(N2HCH3)Br(dppe)2]+Br- b
1.768(14)
1.755(3)
1.758(7)
1.746(5)
1.777(6)
1.741(4)
c
W(NPh)Cl2(PMe3)3
179.5(3)
172.9(1)
170.1(6)
171.4(5)
171.8(4)
W(NC6H3Pri2-2,6)Cl3(dppe)d
W(NCH2CHdCH2)Cl2(PPh2Me)2(CO)e
f
W{NC(Br)C(CN)C(CN)2}Br(dppe)2
[W(NCH2CH3)F(dppe)2]+[BF4]-
a
b
d
Reference 13. Reference 14. c Reference 8a. Reference 8b.
e Reference 8c. f Reference 10a.
imido or hydrazido ligands7 (Table 2). The slight
deviation from linearity may reflect contact with the
C17-C22 and C31-C36 phenyl residues. The distance
from C2 to C32 is 3.55 Å, and that from C2 to C18 is
3.76 Å. The W(1)-N(1) bond length of 1.741 Å is also
typical of a metal-nitrogen triple bond7 (Table 2). It is
noteworthy that the W-N bond length and the W-N-C
bond angle are very similar to the corresponding values
for the analogous hydrazido complex [W(N2H2)-
Cl(dppe)2]+[BPh4]- 13 which was prepared from the bis-
(dintirogen) complex 1 by the protic reduction of a
coordinated dinitrogen ligand. C(2) has a notably large
thermal ellipsoid in the structure, and this could be the
(14) March, F. C.; Mason, R.; Thomas, K. M. J . Organmet. Chem.
1975, 96, C43.
(13) Heath, G. A.; Mason, R.; Thomas, K. M. J . Am. Chem. Soc. 1974,
96, 259.
(15) Hussain, W.; Leigh, G. J .; Ali, H. M.; Pickett, C. J .; Rankin, D.
A. J . Chem. Soc., Dalton Trans. 1984, 1703.

An Ethylimido Complex of Tungsten
Organometallics, Vol. 17, No. 12, 1998 2397
Ta ble 3. Cr ysta llogr a p h ic Da ta for
[WF (NCH2CH3)(d p p e)2]+[BF 4]- (4)
ether (15 mL) resulted in the precipitation of a light brown
solid, which was isolated by filtration and recrystallized from
tetrahydrofuran-ether. [W(OTf)(N2H2)(dppe)2]+[OTf]- (2) was
obtained as a light brown crystalline solid (490 mg, 64%), mp
275-277 °C.
empirical formula
C54H53BF5NP4W
1129.57
fw
cryst color, habit
cryst dimens
lattice param
orange, prism
0.35 × 0.09 × 0.08 mm
a ) 12.237(2) Å
b ) 13.946(3) Å
c ) 16.422(2) Å
R ) 88.82(1)°
â ) 77.09(1)°
γ ) 66.48(2)°
V ) 2497.4(9) Å3
P1h (No. 2)
Anal. Found: C, 49.6; H, 3.9; N, 2.3. Calcd for C54H48
-
F6N2O6P4S2W: C, 49.6; H, 3.7; N, 2.1. 1H NMR (thf-d8): δ 3.04
(m, 8H, PCH2), 5.11 (s(br), 2H, NH2), 7.03, 7.23-7.45 (m, 40H,
P(C6H5)2) ppm. 31P{1H} NMR (thf-d8): δ 37.9 (s (W satellites,
1
d, J W-P ) 284.5 Hz)) ppm. 13C{1H,31P} NMR (thf-d8): δ 31.8
(s, PCH2), 130.8, 131.4, 132.7, 132.9, 134.4, 135.3, 136.0, 136.2
(8 × s, P(C6H5)2) ppm. 19F NMR (thf-d8): δ -73.1 (s, 3F,
W-OTf), -75.2 (s, 3F, -OTf) ppm.
Rea ction of 2 w ith a ceton itr ile-d 3: Syn th esis of tr a n s-
(Aceton itr ile)h yd r a zid obis[1,2-bis(d ip h en ylp h osp h in o)-
eth an e]tu n gsten [W(NCCD3)(N2H2)(dppe)]2+ (5). [W(N2H2)-
(OTf)(dppe)2]+[OTf]- (2; 20 mg, 15 µmol) was dissolved in
acetonitrile-d3 (500 µL, 432 µmol) to yield a purple solution of
[W(NCCD3)(N2H2)(dppe)]2+ (5), which was characterized by
NMR spectroscopy.
1H NMR (CD3CN): δ 2.56 (m, 4H, PCH2CH2P), 2.95 (m, 4H,
PCH2CH2P), 5.97 (s(br), 2H, N2H2), 6.70-7.47 (m, 40H,
P(C6H5)2) ppm. 31P{1H} NMR (CD3CN): δ 39.2 (s (W satellites,
d, 1J W-P ) 278.8 Hz)) ppm. 13C{1H,31P} NMR (CD3CN): δ 29.9
(s, PCH2), 128.2, 129.3, 129.5, 130.6, 131.3, 131.7, 132.1, 132.7
(8 × s, P(C6H5)2)) ppm. 19F NMR (CD3CN): δ -74.8 (s, -OTf)
ppm.
space group
Z
2
Dcalcd
F000
1.502 g/cm3
1136.00
µ(Mo KR)
radiation
25.00 cm-1
Mo KR (λ ) 0.71069 Å),
graphite monochromated
21.0 °C
temperature
2θmax
49.9°
hkl range
-14 to 14, -16 to 16, 0-19
9125
8787 (Rint ) 0.018)
7300
no. of rflns measd
no. of unique rflns
no. of observns
(I > 3.00σ(I))
no. of variables
residuals: R; Rw
goodness-of-fit
indicator
max peak in
final diff map
min peak in
final diff map
595
0.031; 0.032
1.49
a
Syn th esis of tr a n s-(Aceton itr ile)(d in itr ogen )bis[1,2-
bis(d ip h en ylp h osp h in o) eth a n e]tu n gsten , W(NCCH3)-
(N2)(d p p e)2 (3). [W(N2H2)(OTf)(dppe)2]+[OTf]- (2; 300 mg,
230 µmol) was dissolved in acetonitrile (10 mL) and stirred
for 15 min. A solution of sodium borohydride (26 mg, 690
µmol) in ethanol (1 mL) (or Et3N (2.1 equiv) or KOtBu (2.1
equiv)) was added, and the reaction mixture was stirred at
room temperature for 30 min. The resulting dark red pre-
cipitate was isolated by filtration, washed with acetonitrile (2
mL) and ethanol (2 mL), and dried in vacuo. W(N2)(NCCH3)-
(dppe)2 (3) was obtained as a red crystalline solid (182 mg,
76%), mp 192-194 °C (dec).
1.09 e/Å3
-0.74 e/Å3
R ) ∑(|Fo| - |Fc|)2/∑|Fo|. Rw ) (∑w(|Fo| - |Fc|)2/∑w|Fo| )1/2. w
a
2
) 1/σ2(Fo).
X-r a y Cr yst a llogr a p h y. Crystals of [WF(NCH2CH3)-
(dppe)2]+[BF4]- (4) suitable for X-ray crystallography were
obtained by careful recrystallization from ethanol. An orange
prismatic crystal having approximate dimensions 0.35 × 0.09
× 0.08 mm was attached to a thin glass fiber and mounted on
an Enraf-Nonius CAD4 diffractometer employing graphite-
monochromated Mo KR radiation (Table 3). Primitive triclinic
cell constants were obtained from a least-squares refinement
using the setting angles of 25 reflections in the range 18.98 <
2θ < 23.88°. Diffraction data were collected at a temperature
of 21 ( 1 °C using ω-4/3θ scans to a maximum 2θ value of
49.9°. The intensities of three representative reflections,
measured every 60 min, did not change significantly during
the data collection. An analytical absorption correction was
applied, and the data were also corrected for Lorentz and
polarization effects.
All calculations were undertaken with the teXsan16 crystal-
lographic software package. Neutral atom scattering factors
were taken from Cromer and Waber.17 Anomalous dispersion
effects were included in Fc,18 and the values for ∆f ′ and ∆f ′′
were those of Creagh and McAuley.19 The values for the mass
attenuation coefficients were those of Creagh and Hubbell.20
The structure was solved by heavy-atom Patterson methods21
IR (Nujol): 2174 (w(br), CtN), 1886 (w(br), N2) cm-1
.
1H
NMR (C6D6): δ 1.48 (s, 3H, CH3CN), 2.27 (m, 4H), 2.44 (m,
4H, PCH2CH2P), 6.86-7.44 (m, 40H, P(C6H5)2) ppm. 31P{1H}
NMR (C6D6): δ 48.94 (s (W satellites, d, 1J W-P ) 328 Hz)) ppm.
13C{1H,31P} NMR (C6D6): δ 5.0 (s, CH3CN), 32.6 (s, PCH2CH2P),
112.1 (s, CH3CN), 128.7-142.0 (8 × s, P(C6H5)2) ppm.
Rea ction of 3 w ith tetr a flu or obor ic a cid in ben zen e:
Syn th esis of tr a n s-(Eth ylim id o)flu or obis[1,2-bis(d ip h en -
ylp h osp h in o)et h a n e]t u n gst en t et r a flu or ob or a t e, [WF -
(NCH2CH3)(d p p e)2]+[BF 4]- (4). Tetrafluoroboric acid (32 µL,
230 µmol, 7.13 M in diethyl ether) was added to a solution of
W(N2)(NCCH3)(dppe)2 (3; 95 mg, 91 µmol) in benzene (30 mL)
at room temperature. The reaction mixture was stirred for 1
h and filtered through a sintered-glass frit. Addition of ether
(20 mL) to the filtrate precipitated a yellow solid, which was
isolated by filtration. The residue was washed with hexane
(3 mL), thf (1 mL), and hexane (3 mL) and dried in vacuo.
Recrystallization from ethanol afforded [WF(NCH2CH3)-
(dppe)2]+[BF4]- (4) as an orange crystalline solid (60 mg, 58%),
mp 275 °C (dec).
Anal. Found: C, 57.3; H, 4.6; N, 1.1. Calcd C54H53BF5-
NP4W: C, 57.4; H, 4.7; N, 1.2. 1H NMR (CDCl3): δ -0.30 (t,
3H, 3J H-H ) 7.4 Hz, CH3CH2N), 1.91 (dq, 2H, CH3CH2N, 3J H-H
(16) teXsan: Crystal Structure Analysis Package; Molecular Struc-
ture Corp., The Woodlands, TX, 1985 & 1992.
(17) Cromer, D. T.; Waber, J . T. International Tables for X-ray
Crystallography; Kynoch Press: Birmingham, England, 1974; Vol. IV,
Table 2.2A.
(18) Ibers, J . A.; Hamilton, W. C. Acta Crystallogr. 1964, 17, 781.
(19) Creagh, D. C.; McAuley, W. J . In International Tables for
Crystallography; Wilson, A. J . C., Ed.; Vol C, Kluwer Academic:
Boston, 1992; Vol. C. Table 4.2.6.8, pp 219-222.
(20) Creagh, D. C.; Hubbell, J . H. In International Tables for
Crystallography; Wilson, A. J . C., Ed.; Kluwer Academic: Boston, 1992;
Vol. C, Table 4.2.4.3, pp 200-206.
4
) 7.4 Hz, J H-F ) 3.7 Hz), 2.62 (m, 4H, PCH2CH2P), 2.78 (m,
4H, PCH2CH2P), 7.10-7.39 (m, 40H, P(C6H6)2) ppm. 31P{1H}
2
NMR (CDCl3): δ 33.6 (d, J F-P ) 44.5 Hz (W satellites, dd,
2
1J W-P ) 293.0 Hz, J F-P ) 44.5 Hz)) ppm. 13C{1H,31P} NMR
(CDCl3): δ 14.1 (s, CH3CH2N), 32.5 (s, PCH2CH2P), 57.8 (s,
CH3CH2N), 129.7, 130.2, 131.8, 132.1, 134.0, 134.3, 135.1,
135.7 (8 × s, P(C6H5)2) ppm. 19F NMR (CDCl3): δ -174.8 (qu,
2
1F, J F-P ) 44.6 Hz, WF ), -149.9 (br s, 4F, BF 4-) ppm.

2398 Organometallics, Vol. 17, No. 12, 1998
Field et al.
and expanded using Fourier techniques.22 Non-hydrogen
atoms were modeled with anisotropic thermal parameters.
Hydrogen atoms were included in the model at calculated
positions with group thermal parameters. Slight residual
electron density in the vicinity of the BF4- counterion suggests
minor orientational disorder, which was not modeled. An
ORTEP projection of the molecule is provided in Figure 1.23
Su p p or tin g In for m a tion Ava ila ble: Tables S1-S8, giv-
ing all bond distances and angles, atomic coordinates, and
thermal parameters for complex 4 (15 pages). Ordering
information is given on any current masthead page.
OM970829V
(22) DIRDIF94: Beurskens, P. T.; Admiraal, G.; Beurskens, G.;
Bosman, W. P.; de Gelder, R.; Israel, R.; Smits, J . M. M. The DIRDIF-
94 Program System, Technical Report of the Crystallography Labora-
tory; University of Nijmegen, Nijmegen, The Netherlands, 1994.
(23) ORTEP: J ohnson, C. K. ORTEPII, Report ORNL-5138; Oak
Ridge National Laboratory, Oak Ridge, TN, 1976.
(21) PATTY: Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bos-
man, W. P.; Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla,
C. The DIRDIF Program System; Technical Report of the Crystal-
lography Laboratory; University of Nijmegen, Nijmegen, The Nether-
lands, 1992.