Syntheses, structures, and reactions of η2-N-acylamido-N,O hydrido complexes of molybdenum(II) and tungsten(II)

Article abstract of DOI:10.1021/om9603124

The N-acylamido complexes [MH{N(R¹)COR²-N,O}(dppe)₂] (M = Mo, W; R¹/R² = Me/Me, Ph/Me, Me/H, Ph/H, (CH₂)₃, Ph/Ph; dppe = Ph₂PCH₂CH₂PPh₂) were synthesized by photochemical or thermal reactions of [MoH₄(dppe)₂] or trans-[W(N₂)₂(dppe)₂] with N-alkylamides R¹NHCOR². An X-ray study of [MoH{N(CH₃)COCH₃-N,O}(dppe)₂] revealed a distorted-pentagonal-bipyramidal configuration with two phosphorus atoms, the nitrogen and the oxygen atoms of the amide, and a hydride lying in the equatorial plane. These complexes reacted with methanol or ethanol in toluene at ambient temperature to give the novel alkoxo hydrido complexes [MH₂(OR)₂(dppe)₂] (R = Me, Et). The reactions apparently proceeded via a coordinatively unsaturated 16e intermediate, which is formed upon release of the N-acylamido ligand. The reactions between the amido complexes and catechols yielded the chelated catecholato complexes [MH₂(catecholato-O,O′)(dppe)₂] (catecholato = O₂C₆H₄, O₂C₆H₃(4-Me), O₂C₆H₃(4-Bu^t), O₂C₆H₃(4-COOEt), and O₂C₁₀H₆). The structures of catecholato complexes, determined by single-crystal X-ray diffraction studies, exhibit distorted-dodecahedral geometry.

Full text of DOI:10.1021/om9603124

Organometallics 1996, 15, 4863-4871
4863
Syn th eses, Str u ctu r es, a n d Rea ction s of
η2-N-Acyla m id o-N,O Hyd r id o Com p lexes of
Molybd en u m (II) a n d Tu n gsten (II)
Makoto Minato, Hiroyuki Sakai, Zu-Gan Weng, Da-Yang Zhou,
Susumu Kurishima, and Takashi Ito*
Department of Materials Chemistry, Faculty of Engineering, Yokohama National University,
156 Tokiwadai, Hodogaya-ku, Yokohama 240, J apan
Mikio Yamasaki and Motoo Shiro
Rigaku Corporation, Matsubara-Cho, Akishima, Tokyo 196, J apan
Masako Tanaka and Kohtaro Osakada
Research Laboratory of Resources Utilization, Tokyo Institute of Technology, 4259 Nagatsuta,
Midori-ku, Yokohama 227, J apan
Received April 24, 1996X
The N-acylamido complexes [MH{N(R1)COR2-N,O}(dppe)2] (M ) Mo, W; R1/R2 ) Me/Me,
Ph/Me, Me/H, Ph/H, (CH2)3, Ph/Ph; dppe ) Ph2PCH2CH2PPh2) were synthesized by
photochemical or thermal reactions of [MoH4(dppe)2] or trans-[W(N2)2(dppe)2] with N-
alkylamides R1NHCOR2. An X-ray study of [MoH{N(CH3)COCH3-N,O}(dppe)2] revealed a
distorted-pentagonal-bipyramidal configuration with two phosphorus atoms, the nitrogen
and the oxygen atoms of the amide, and a hydride lying in the equatorial plane. These
complexes reacted with methanol or ethanol in toluene at ambient temperature to give the
novel alkoxo hydrido complexes [MH2(OR)2(dppe)2] (R ) Me, Et). The reactions apparently
proceeded via a coordinatively unsaturated 16e intermediate, which is formed upon release
of the N-acylamido ligand. The reactions between the amido complexes and catechols yielded
the chelated catecholato complexes [MH2(catecholato-O,O′)(dppe)2] (catecholato ) O2C6H4,
O2C6H3(4-Me), O2C6H3(4-But), O2C6H3(4-COOEt), and O2C10H6). The structures of catecholato
complexes, determined by single-crystal X-ray diffraction studies, exhibit distorted-dodeca-
hedral geometry.
In tr od u ction
plexes are known, and this reaction is intriguing.4 Here
we report the synthesis and spectroscopic and crystal-
lographic characterization of these complexes. We also
describe in detail the reactions of a (N-acylamido)-
hydridomolybdenum complex with aliphatic alcohols
and catechol derivatives, together with structural analy-
ses for some catecholato complexes. Further, we have
The field of organomolybdenum chemistry has grown
rapidly over the last few years, partly because of
biological interest. Inter alia, studying interactions
between molybdenum complexes and nitrogen com-
pounds is important in its relevance to nitrogenase
models.1 Our continuing interest in the chemistry of
molybdenum polyhydrides2 prompted us to investigate
the reaction of MoH4(dppe)2 (1; dppe ) Ph2PCH2CH2-
PPh2), which is kinetically a very reactive species and
undergoes a wide variety of transformations,3 with
N-alkylamides. We have found that the photochemical
or thermal reaction yielded [MoH{N(R1)COR2-N,O}-
(dppe)2] (2) as a result of the oxidative addition which
involves amide N-H bond cleavage. Very few examples
of a direct oxidative addition of an N-H bond of
unfunctionalized amides to the transition-metal com-
tried to extend this work to tungsten complexes.
A
preliminary account of some of this work has already
appeared.5
Resu lts a n d Discu ssion
Syn th esis a n d Sp ectr oscop ic Ch a r a cter iza tion
of Hyd r id o(N-a cyla m id o-N,O)m olybd en u m (2) a n d
-tu n gsten (3) Com p lexes. Most complexes containing
a nitrogen-metal bond are prepared by a simple me-
tathesis reaction between a transition-metal halide and
an alkali-metal salt of an amine. The strongly basic
conditions required restrict the flexibility of this ap-
proach. We have now found a convenient synthetic
route to (N-acylamido)hydridomolybdenum complexes,
in which the reaction proceeds under neutral conditions.
X Abstract published in Advance ACS Abstracts, October 1, 1996.
(1) Hidai, M.; Mizobe, Y. In Molybdenum Enzymes, Cofactors and
Model Systems; Stiefel, E. I.; Coucouvanis, D., Newton, W. E., Eds.;
ACS Symposium Series 535; American Chemical Society: Washington,
DC, 1993; Chapter 22.
(2) (a) Ito, T.; Tosaka, H.; Yoshida, S.; Mita, K.; Yamamoto, A.
Organometallics 1986, 5, 735. (b) Ito, T.; Hamamoto, K.; Kurishima,
S.; Osakada, K. J . Chem. Soc., Dalton Trans. 1990, 1645. (c) Ito, T.;
Matsubara, T.; Yamashita, Y. J . Chem. Soc., Dalton Trans. 1990, 2407.
(d) Kurishima, S.; Ito, T. Chem. Lett. 1990, 1299. (e) Minato, M.;
Kurishima, S.; Nagai, K.; Yamasaki, M.; Ito, T. Chem. Lett. 1994, 2339.
(3) (a) Pennela, F. J . Chem. Soc., Chem. Commun. 1971, 158. (b)
Pennela, F. Inorg. Synth. 1974, 15, 42.
(4) (a) Schaad, D. R.; Landis, C. R. J . Am. Chem. Soc. 1990, 112,
1628. (b) Hursthouse, M. B.; Mazid, M. A.; Robinson, S. D.; Sahajpal,
A. J . Chem. Soc., Chem. Commun. 1991, 1146.
(5) Ito, T.; Kurishima, S.; Tanaka, M.; Osakada, K. Organometallics
1992, 11, 2333.
S0276-7333(96)00312-3 CCC: $12.00 © 1996 American Chemical Society

4864 Organometallics, Vol. 15, No. 22, 1996
Ta ble 1. P r ep a r a tion s of Com p lexes [MH{N(R1)COR2-N,O}(d p p e)2] (M ) Mo (2), W (3))
substrate
amide (R1, R2)/amt, mmol
Minato et al.
compd
complex/amt, mmol
solvent/amt, mL
conditions
yield, %
2a
2a
2b
2b
2c
2c
2d
2d
2e
2e
2f
{Mo}H4a/0.27
{Mo}H4a/1.40
{Mo}H4a/0.38
{Mo}H4a/0.71
{Mo}H4a/0.27
{Mo}H4a/0.54
{Mo}H4a/0.72
{Mo}H4a/0.72
{Mo}H4a/0.23
{Mo}H4a/0.36
{Mo}H4a/0.43
{Mo}H4a/0.67
{W}(N2)2b/1.43
{W}(N2)2b/1.32
CH3, CH3/0.27
CH3, CH3/1.84
Ph, CH3/0.44
Ph, CH3/0.78
CH3, H/0.27
CH3, H/0.53
Ph, H/0.93
benzene/27
toluene/40
benzene/30
toluene/20
benzene/27
toluene/20
benzene/70
toluene/20
benzene/23
toluene/18
benzene/30
toluene/20
toluene/50
benzene/50
20 °C, hν, 3 h
26
50
31
58
36
28
44
40
52
47
36
37
11
12
110 °C, 3 h
20 °C, hν, 3 h
110 °C, 3h
20 °C, hν, 3 h
110 °C, 5 h
20 °C, hν, 5 h
110 °C, 3 h
20 °C, hν, 3 h
110 °C, 5 h
20 °C, hν, 3 h
110 °C, 3 h
110 °C, 6 h
50 °C, 6 h/80 °C, 0.5 h
Ph, H/1.02
-(CH2)3-/0.23
-(CH2)3-/0.36
Ph, Ph/0.44
Ph, Ph/0.73
CH3, CH3/2.90
Ph, CH3/2.60
2f
3a
3b
a
b
{Mo}H4 ) [MoH4(dppe)2]. {W}(N2)2 ) trans-[W(N2)2(dppe)2].
Ta ble 2. IR a n d An a lytica l Da ta for [MH{N(R1)COR2-N,O}(d p p e)2] (M ) Mo (2), W (3))
IRa/cm-1
elemental anal.b
compd
ν(M-H)
ν(C-O)
C, %
H, %
N, %
2a
3a
2b
3b
2c
2d
2e
2f
1810 (vw)
1893 (w)
1880 (vw)
1951 (w)
1810 (w)
1880 (w)
c
1560 (s)
1580 (s)
1530 (s)
1580 (s)
1580 (s)
1540 (s)
1560 (s)
1530 (s)
67.94 (68.32)
d
69.28 (70.10)
d
67.38 (68.14)
68.81 (69.89)
69.59 (68.71)
70.82 (71.62)
5.81 (5.84)
1.52 (1.45)
6.22 (5.58)
1.31 (1.36)
5.69 (5.61)
6.10 (5.47)
5.80 (5.77)
6.08 (5.46)
1.12 (1.47)
1.19 (1.38)
2.02 (1.43)
1.50 (1.29)
c
a
b
d
KBr disk. Calculated values in parentheses. c Not discernible. Not performed.
The photochemical reaction of MoH4(dppe)2 with
N-alkylamides in benzene yielded [MoH{N(R1)COR2-
N,O}(dppe)2] as a result of the oxidative addition
involving amide N-H bond cleavage. The closely
related phenylamide complex [MoH{N(COH)C6H5}-
(PMe3)5] has been synthesized by the reaction of phenyl
isocyanate with [MoH2(PMe3)5],6 but to our knowledge
this is the first example of the direct oxidative addition
of an amide N-H group to a group 6 transition-metal
complex. Further, though several examples of the
oxidative addition of a highly polarized N-H bond of a
cyclic imide, such as succinic and phthalic imides, have
been reported,7 there are only two precedents for the
oxidative addition of simple amides.4 Preparative, IR,
and analytical data for the complexes are compiled in
Tables 1 and 2.
Similar results were obtained when 1 and amides
were heated at 110 °C in toluene for 3-5 h. The yields
of 2 ranged from 26% (for a , photoreaction) to 58% (for
b, thermal reaction), and the amount of H2 evolved was
estimated to be roughly twice the yield of 2. In the
thermal reaction of N-phenylformamide (d ), the known
cis-[Mo(CO)2(dppe)2] was observed in addition to 2d ,
suggesting that the concurrent insertion reaction of 1
into the formyl C-H bond takes place. A larger ratio
of d /1 afforded a higher yield of this carbonyl complex,
and the formation of aniline (14%) was observed when
d /1 was 1.31. The formation of a carbonyl complex by
the reaction of a molybdenum(0) complex with N,N-
dimethylformamide has been reported.8
Sch em e 1
The analogous tungsten complex [WH{N(R1)COR2-
N,O}(dppe)2] (3) were prepared similarly, although
trans-[W(N2)2(dppe)2] was used instead of [WH4(dppe)2]
because the dinitrogen complex is more reactive than
the tetrahydride in the synthesis of hydrido(malonato)-
tungsten complexes.2e However, the yield of complex 3
was less than that of 2, possibly due to the low reactivity
of trans-[W(N2)2(dppe)2]. The related tungsten carbam-
oyl hydrido complex [WH{η2-C(O)N(CH3)2}(dppe)2], in
which carbon and oxygen ligate to tungsten, was
prepared from the reaction of trans-[W(N2)2(dppe)2] with
N,N-dimethylformamide.9
The reaction of 2 with acetic acid in benzene at
ambient temperature gave N-phenylbenzamide and
[MoH(O2CCH3-O,O′)(dppe)2], which has already been
synthesized by the photoreaction of 1 with allyl acetate.2c
As shown in Table 2, the amide I band in the IR
spectra of 2 and 3 shifts to lower frequency by about
(6) Lyons, D.; Wilkinson, G.; Thornton-Pett, M.; Hursthouse, M. B.
J . Chem. Soc., Dalton Trans. 1984, 695.
(7) (a) Roundhill, D. M. Inorg. Chem. 1970, 9, 254. (b) Kohara, T.;
Yamamoto, T.; Yamamoto, A. J . Organomet. Chem. 1978, 154, C37.
(c) Ikariya, T.; Takizawa, S.; Shirado, M.; Yoshikawa, S. J . Organomet.
Chem. 1979, 171, C47. (d) Yamamoto, T.; Sano, K.; Yamamoto, A.
Chem. Lett. 1982, 907. (e) Kurishima, S.; Matsuda, N.; Tamura, N.;
Ito, T. J . Chem. Soc., Dalton Trans. 1991, 1135.
(8) Sato, M.; Tatsumi, T.; Kodama, T.; Hidai, M.; Uchida, T.; Uchida,
Y. J . Am. Chem. Soc. 1978, 100, 4447.
(9) (a) Ishida, T.; Mizobe, Y.; Tanase, T.; Hidai, M. J . Organomet.
Chem. 1991, 409, 355. (b) Ishida, T.; Mizobe, Y.; Tanase, T.; Hidai,
M. Chem. Lett. 1988, 441.

η2-N-Acylamido-N,O Hydrido Complexes of Mo and W
Organometallics, Vol. 15, No. 22, 1996 4865
Ta ble 3. 1H a n d 13C NMR Da ta for [MH{N(R1)COR2-N,O}(d p p e)2] (M ) Mo (2), W (3))
compd
1H NMRa
13C NMRb
2a
-4.92 (dddd, MoH, J HP ) 17.7, 35.4, 59.8, 79.3 Hz, 1H), 0.66 (s, OCCH3, 3H), 1.85 (s, NCH3, 3H) 169.6 (OCCH3), 34.3 (NCH3),
18.9 (OCCH3)
3a
-3.58 (m, WH, 1H), 0.62 (s, OCCH3, 3H), 1.92 (s, NCH3, 3H)
168.7 (OCCH3), 34.2 (NCH3),
19.4 (OCCH3)
2b
3b
2c
2d
2e
2f
-5.46 (dddd, MoH, J HP ) 15.4, 29.1, 56.4, 90.6 Hz, 1H), 1.23 (s, OCCH3, 3H), 7 (m, NC6H5, 5H) 170.1 (OCCH3), 21.7 (OCCH3)
-3.57 (dddd, WH, J HP ) 12.0, 22.4, 54.8, 96.0 Hz, 1H), 1.23 (s, OCCH3, 3H), 7 (m, NC6H5, 5H)
-5.11 (dddd, MoH, J HP ) 16.5, 36.6, 56.8, 81.8 Hz, 1H), 1.80 (s, NCH3, 3H)
169.5 (OCCH3), 22.2 (OCCH3)
161.1 (OCH)
-5.53 (dddd, MoH, J HP ) 15.0, 26.5, 57.7, 90.6 Hz, 1H), 7.46 (s, OCH, 1H), 7 (m, NC6H5, 5H)
-5.05 (dddd, MoH, J HP ) 20.1, 32.4, 61.0, 76.9 Hz, 1H), 1-3 (m, NCH2CH2CH2, 6H)
-4.58 (dddd, MoH, J HP ) 14.1, 38.9, 50.4, 89.3 Hz, 1H), 7 (m, NC6H5, OCC6H5, 10H)
162.2 (OCH)
175.9 (NCOCH2)
165.2 (OCC6H5)
a
b
Conditions: C6D6, in ppm, 293 K, 270 MHz, TMS reference. Conditions: C6D6, in ppm, 293 K, 67.8 MHz, TMS reference.
Sch em e 2
F igu r e 1. ORTEP drawing of the molecular structure of
2a , with the atom-numbering scheme.
Ta ble 4. In ter a tom ic Dista n ces (Å) a n d An gles
(d eg) for 2a
100 cm-1 as compared with this band in the free amide.
This, together with the disappearance of the amide II
Distances
Mo-P(1)
Mo-P(3)
Mo-N
2.421(5)
2.424(5)
2.25(1)
1.29(2)
1.42(2)
Mo-P(2)
Mo-P(4)
Mo-O
N-C(1)
C(1)-C(3)
2.421(5)
2.447(5)
2.24(1)
1.35(2)
1.46(3)
and the ν(N-H) bands, imply N-H bond cleavage and
a mode of coordination in which amide forms a four-
membered chelate ring, as shown above. The Mo-H
stretching bands of complexes 2 were observed at 1810-
1880 cm-1, values typical of ν(Mo-H) for [MoHX-
(dppe)2]-type complexes.2 In the 1H NMR spectra of
complex 2 (Table 3), hydride signals appeared at around
δ -5, with a multiplicity corresponding to an ACKMX
spin system. These signals are consistent with the four
isolated signals in 31P{1H} NMR spectra, each being
split into a doublet of doublets of doublets (ACKM spin
system). In the 13C NMR spectra of 2, the resonances
attributable to the carbonyl carbons were observed in
the range δ 165-175.
O-C(1)
N-C(2)
Angles
57.9(4)
93.4(3)
90.0(3)
N-Mo-O
N-Mo-P(1)
N-Mo-P(3)
O-Mo-P(3)
P(1)-Mo-P(4)
82.4(3)
141.5
83.6(3)
168.8(2)
N-Mo-P(2)
N-Mo-P(4)
P(2)-Mo-P(3)
124.8(2)
trans-[W(N2)2(dppe)2] affords a coordinatively unsat-
urated reactive W(0) dinitrogen intermediate in a
similar manner as 1, and it supposedly adds the amide
N-H bond to give 3.
Cr ysta l Str u ctu r e Deter m in a tion of Com p lex 2a .
Complex 2a has been fully characterized by an X-ray
diffraction study. Details of the crystal structure de-
termination have already been published.5 Some im-
portant features of the structure will be described here
(see Figure 1 and Table 4).
The complex may be regarded as having a distorted-
pentagonal-bipyramidal structure with two phosphorus
atoms of dppe, the nitrogen and the oxygen atoms of
the amide, and a hydride comprising the equatorial
plane. The total of the bond angles around the molyb-
denum atom ( P(2)-Mo-P(3) + P(3)-Mo-O + O-
Mo-N + N-Mo-P(2)) is 359.7°, which suggests a
strictly flat equatorial plane and confirms the planarity
of the MoN{(COCH3)CH3} moiety. The C-O bond
distance in 2a is 1.29(2) Å, which is significantly longer
than the corresponding bond distance of free N-methyl-
acetamide (1.225 Å), and the C(1)-N bond distance is
1.35(2) Å, which is slightly shorter than that of the free
amide (1.386 Å). The Mo-N distance of 2.25(1) Å is
slightly shorter than the Mo-N σ-bond distance (2.32
Å) reported for [Mo(CO)3(diethylenetriamine)],10 and the
A possible mechanism for the formation of complex 2
is illustrated in Scheme 2.
The mechanism involves the initial evolution of 1 mol
of H2 from the molybdenum complex upon irradiation
or heating to generate the 16-electron reactive inter-
mediate [MoH2(dppe)2], followed by oxidative addition
of a N-H bond to molybdenum to give a trihydrido
species, which subsequently rearranges to the final
product with evolution of a further 1 mol of H2. The
photoreaction of 1 is known to give the coordinatively
unsaturated 14-electron species with evolution of 2 mol
of H2, and a pathway which involves direct N-H bond
oxidative addition to this intermediary 14-electron Mo-
(dppe)2 is also possible. Similar reaction paths involving
C-O, C-H, or N-H bond cleavage have been consid-
ered for the reaction of 1 with allyl carboxylates and
allyl alkyl carbonates, alkyl malonates, or cyclic imides,
respectively.2 An alternative pathway which involves
initial protonolysis of 1 with amide may also be possible.4a
However, this appears to be less likely for the following
reasons: (a) the acidity of the amides used here is not
high enough and (b) the amide concentration influences
neither the reaction rate nor the yield of product.
(10) Cotton, F. A.; Wing, R. M. Inorg. Chem. 1965, 4, 314.

4866 Organometallics, Vol. 15, No. 22, 1996
Minato et al.
Sch em e 3
Mo-O distance (2.24(1) Å) is also shorter than those of
the related complex [MoH(O2COEt-O,O′)(dppe)2]
(2.271(2) and 2.333(3) Å).2b These data and the long
C-O distance and the short Mo-N distance in 2a
suggest the following resonance forms of the η2-amide:
Rea ction s of 2a a n d 3a w ith ROH (R ) Me, Et,
P r i). In the course of working up complexes 2 and 3,
we observed that they were highly susceptible to elec-
trophiles such as alcohols, suggesting that they can be
used to synthesize a variety of new molybdenum or
tungsten organometallic complexes. In addition to their
novel reactivity, the potential of metal alkoxides in
catalysis11 led us to study in detail the reaction of 2a or
3a with a variety of alcohols.
When 2a was treated with methanol at ambient
temperature for 12 h, the moderately air-sensitive
yellowish dihydridodimethoxomolybdenum complex
[MoH2(OMe)2(dppe)2] (4) was formed quantitatively,
together with the corresponding organic amide. Since
the tetrahydrido complex 1 does not react with metha-
nol, the amide of 2a seems to play a crucial role in the
reaction. Treatment of the tungsten complex 3a with
methanol gave the analogous [WH2(OMe)2(dppe)2] (5)
in 34% yield.
magnetically to the phosphorus atoms, and quintet
signals appear at δ -2.29 (2J HP ) 34.6 Hz) for 4. This
coupling constant is much smaller than that of [MoH2-
Cl2(dppe)2] (2J HP ) 48 Hz).15 The quintet hydride
resonance of complex 4 indicates that the four phos-
phorus atoms are equivalent at this temperature due
to fluxionality.16 Similar behavior is sometimes ob-
served for related eight-coordinate complexes.17 The 1H
NMR spectrum of tungsten complex 5 displays a broad-
ened multiplet resonance at around δ -1.1 assignable
to the hydride, at a lower field than that of 4 by about
1.2 ppm. A similar observation was made for the amido
complexes, as described previously. The NMR data
support a cis arrangement of the hydrides in complex
4, which was substantiated by the similar features
observed in analogous hydrido catecholato complexes,
whose structures were fully confirmed by single-crystal
X-ray analyses (vide infra).
One possible pathway for the formation of complex 4
is outlined in Scheme 3.
The first step is replacement of amide by methanol,
which acts as a proton source, followed by direct
oxidative addition of an O-H bond of another molecule
of MeOH to the intermediate 16-electron species. There
are a few examples of the oxidative addition of alcohols
involving O-H cleavage.18 It is noteworthy that the
reaction of complex 2a with an acid as weak as metha-
nol proceeds at ambient temperature without any forced
activation, in view of the fact that irradiation or heating
is necessary for the tetrahydride 1 to generate the
coordinatively unsaturated reactive intermediate [MoH2-
(dppe)2].19 trans-[Mo(N2)2(dppe)2]20 is also known to be
reactive but does not react with methanol at ambient
temperature.
We observed that 4 gradually changes into the
formaldehyde complex [MoH2(η2-CH2O)(dppe)2]12 in ben-
zene, the conversion being significantly retarded in
toluene. A related η2-formaldehyde complex of tungsten
[W(PMe3)4(η2-CH2O)H2] has been prepared by Green
and co-workers.13 At 180 °C, 4 decomposes quantita-
tively to trans-[Mo(CO)2(dppe)2].14
∆
[MoH2(OMe)2(dppe)2]
8 trans-[Mo(CO)2(dppe)2]
-H2
4
(2)
The elemental analysis of complex 4 supports the
formulation given. The hydride resonances are coupled
The addition of acetic acid (1 equiv) to a toluene
solution of 4 resulted in the formation of a seven-
coordinate pentagonal-bipyramidal (acetato)hydrido-
(11) (a) Cotton, F. A.; Wilkinson, G. Advanced Inorganic Chemistry,
5th ed.; Wiley: New York, 1988; pp 471-474. (b) Bryndza, H. E.; Tam,
W. Chem. Rev. 1988, 88, 1163.
(15) Chatt, J .; Heath, G. A.; Richards, R. L. J . Chem. Soc., Dalton
Trans. 1974, 2074.
(16) Cotton, F. A.; Wilkinson, G. Advanced Inorganic Chemistry, 5th
ed.; Wiley: New York, 1988; p 1322.
(17) See for example: Hills, A.; Hughes, D. L.; Kashef, N.; Lemos,
M. A. N. D. A.; Pombeiro, A. J . L.; Richards, R. L. J . Chem. Soc., Dalton
Trans. 1992, 1775.
(18) See for example: Osakada, K.; Ohshiro, K.; Yamamoto, A.
Organometallics 1991, 10, 404.
(19) Geoffroy, G. L.; Wrighton, M. S. Organometallic Photochemistry;
Academic Press: New York, 1979; p 278.
(20) Hidai, M.; Tominari, K.; Uchida, Y. J . Am. Chem. Soc. 1972,
94, 110.
(12) This complex was identified by an NMR tube reaction in C6D6.
2
[MoH2(OCH2)(dppe)2]: 1H NMR (270 MHz) δ -2.99 (qnt, J HP ) 34.6
Hz, 2H, Mo-H), 2.10 (br, 2H, OdCH2); 13C NMR (78.8 MHz) δ 64.1 (t,
OdCH2, J CH ) 167.2 Hz); 31P{1H} NMR (36.5 MHz, chemical shifts
are in ppm with downfield positive from the external benzene solution
of PPh3) 71.3 (br, s); 13C{1H off-resonance decoupled} NMR 64.1 (t,
J CH ) 167.2 Hz, OdCH2).
(13) Green, M. L. H.; Parkin, G.; Moynihan, K.; Prout, K. J . Chem.
Soc., Chem. Commun. 1984, 1540.
(14) (a) Holden, L. K.; Mawby, A. H.; Smith, D. C.; Whyman, R. J .
Organomet. Chem. 1973, 55, 343. (b) Chatt, J .; Watson, H. R. J . Chem.
Soc. 1961, 4980.

η2-N-Acylamido-N,O Hydrido Complexes of Mo and W
Organometallics, Vol. 15, No. 22, 1996 4867
Sch em e 4
Sch em e 5
molybdenum complex with evolution of methanol (1.84
mol/mol of 4). This complex has already been synthe-
sized by the photoreaction of 1 with allyl acetate.2b,c
Treatment of 2a with phenol in toluene at ambient
temperature gave hydride-free product. However, it
could not be characterized owing to its low solubility
toward common organic solvents.
Rea ction s of 2a a n d 3a w ith Ca tech ol Der iva -
tives. Complex 2a reacts with the series of catechol
derivatives to give the corresponding chelated catecho-
lato-O,O′ hydrido complexes 7 in good yield. Although
molybdenum catecholate complexes containing oxo
ligands are well-known, the analogous complex with a
tertiary phosphine is relatively rare.23,24
Complex 2a reacts with ethanol, as it does with
methanol, to give the corresponding diethoxodihydri-
domolybdenum complex 6. Complex 6 is much more
unstable and decomposes in solution at slightly elevated
temperatures to give the carbonyl complex cis-[Mo(CO)2-
(dppe)2]14 with evolution of methane and dihydrogen.
Treatment of 3a similarly results in the formation of
tungsten complexes 8. The thermal stabilities of these
complexes are much higher than those of the corre-
sponding aliphatic dialkoxo complexes, probably due to
the absence of the â-hydrogen atoms in the catecholates.
Preparative, analytical, and selected spectroscopic data
for the complexes are compiled in Tables 5-7, respec-
tively.
Relatively strong absorption bands at 1256-1293
cm-1 (ν(C-O)) in 7 and 8 are observed, typical of
catecholato complexes.25 The anomalously low-field
shift of hydride signals in the tungsten complex 8 (δ
0.14-0.23) is noteworthy. A comparison of the 1H NMR
spectra of complexes 7a -c reveals substantial similari-
ties in the positions, multiplicities, and coupling con-
stants of the hydride resonances, suggesting that sub-
stituents on the aromatic ring of catechol do not
influence profoundly the electronic state of the central
metal. In contrast to 7a -c, the hydride region of 7d at
Repeated attempts to isolate 6 in an analytically pure
form were unsuccessful due to its extreme lability.
The tetrahydrido complex 1 was formed quantita-
tively by treatment of 2a with 2-propanol at ambient
temperature. Formation of acetone was observed by gas
chromatography in this reaction, suggesting that the
reaction proceeds via a â-hydrogen elimination process
from an isopropoxo intermediate, as shown in Scheme
4.21
In contrast, complex 2a does not react with sterically
hindered alcohols such as pinacol and 2-methyl-2-
propanol even under prolonged heating in refluxing
toluene. dppe, which bears sterically demanding Ph
substituents, may prevent the approach of bulky alco-
hols to the molybdenum atom. These results are in
contrast with those of Richards et al., who reported that
reaction of trans-[Mo(N2)2(dppe)2] with the bulky thiols
RSH gives the monohydride complexes [MoH(SR)-
(dppe)2].22
293 K displays a triplet of triplets resonance (2J HP
)
26.5 and 70.2 Hz), which collapses at 323 K into a
quintet resonance (2J HP ) 48.0 Hz). In contrast to 4,
the 31P NMR spectrum of 7a contains two resonances
of equal intensity at δ 36.4 and 76.3. The chelating
catecholate appears to prevent the fluxional behavior
(23) For reviews see: Pierpont, C. G.; Buchanan, R. M. Coord. Chem.
Rev. 1981, 38, 45.
(24) (a) Atovmyan, L. O.; Tkachev, V. V.; Shishova, T. G. Dokl. Akad.
Nauk SSSR 1972, 205. (b) Buchanan, R. M.; Pierpont, C. G. Inorg.
Chem. 1979, 18, 1616. (c) Tkachev, V. V.; Atovmyan, L. O. Koord.
Khim. 1975, 1, 845.
(21) Bernard, K. A.; Rees, W. M.; Atwood, J . D. Organometallics
1986, 5, 390.
(22) Richard, A. H.; Hughes, D. L.; Richards, R. L.; Shortman, C. J .
Chem. Soc., Dalton Trans. 1987, 1115.
(25) Griffith, W. P.; Pumphrey, C. A.; Rainey, T.-A. J . Chem. Soc.,
Dalton Trans. 1986, 1125.

4868 Organometallics, Vol. 15, No. 22, 1996
Minato et al.
Ta ble 5. P r ep a r a tion of [MH2(Ca t)(d p p e)2] (Ca t ) C6H4O2 (a ), 4-MeC6H3O2 (b), 4-Bu tC6H3O2 (c),
4-CO2EtC6H3O2 (d ), a n d C10H6O2 (e))
compd
catechol/amt, mmol
amt of complex 2a or 3a , mmol
amt of toluene, mL
time, h
yield, %
7a (M ) Mo)
8a (M ) W)
7b (M ) Mo)
8b (M ) W)
7c (M ) Mo)
8c (M ) W)
7d (M ) Mo)
8d (M ) W)
7e (M ) Mo)
8e (M ) W)
C6H4(OH)2/0.348
C6H4(OH)2/0.144
0.225
0.133
0.193
0.129
0.150
0.160
0.137
0.151
0.202
0.124
25
15
20
13
15
16
15
20
20
13
5
8
80
47
69
44
79
65
47
53
83
44
4-MeC6H3(OH)2/0.196
4-MeC6H3(OH)2/0.147
4-ButC6H3(OH)2/0.285
4-ButC6H3(OH)2/0.1.72
4-CO2EtC6H3(OH)2/0.285
4-CO2EtC6H3(OH)2/0.154
12
48
12
48
12
48
12
8
C
C
10H6(OH)2/0.214
10H6(OH)2/0.142
Ta ble 6. IR a n d An a lytica l Da ta for
[MoH2(Ca t)(d p p e)2] (M ) Mo (7), W (8))
Both complexes 7a and 8a are chiral, and the correct
enantiomorphs were determined by R indices (see Table
8).
IRa/cm-1
elemental anal.b
The crystals belong to the orthorhombic (7a , 8a ) or
to the monoclinic (7d ) system. The complexes possess
distorted-dodecahedral coordination, with the two P
atoms and the catecholate in the pseudo-equatorial
basal plane and the hydrides and the other two P atoms
in the apical sites as shown in Figures 2-4. A number
of related hydride complexes with the phosphines have
a dodecahedral structure, e.g. [MoH3(CtCBut)(dppe)2]26
and [WH2Cl2(PMe2Ph)4].27 The catecholates form sym-
metrical five-membered chelate rings.
compd ν(M-H)
ν(C-O)
C, %
H, %
7a
8a
7b
8b
7c
8c
7d
8d
7e
8e
1841 (m) 1263 (s)
1877 (m) 1260 (s)
69.61 (69.46) 5.43 (5.43)
63.63 (63.86) 5.04 (4.99)
1823 (m) 1256 (s), 1271 (s) 70.32 (69.69) 5.92 (5.55)
1882 (m) 1257 (s), 1273 (s) 64.67 (64.14) 5.55 (5.11)
1841 (m) 1264 (s), 1280 (s) 70.80 (70.32) 6.27 (5.90)
1882 (m) 1265 (s), 1280 (s) 64.87 (64.93) 5.60 (5.45)
1828 (m) 1275 (s), 1293 (s) 70.80 (70.32) 6.27 (5.90)
1889 (m) 1276 (s), 1293 (s)
1838 (m) 1284 (s)
1884 (m) 1286 (s)
c
c
70.64 (70.72) 5.27 (5.36)
c
c
a
KBr disk. b Calculated values in parentheses. c Not performed.
The mean Mo-P distances are 2.480 and 2.484 Å for
7a and 7d , respectively, and these distances are close
to that found in 1 (2.420 Å).28
The bond distances and angles of the molybdenum-
catecholato moiety are as expected. The mean Mo-O
bond distances are 2.130 and 2.132 Å for 7a and 7d ,
respectively, which are a little longer than that of
complex [MoO2(O2C6H4)2]2- by ca. 0.03 Å,24c and these
values indicate that a strong electron-withdrawing
substituent such as the ethoxycarbonyl group does not
influence the length of the Mo-O bond. The mean
W-O distance of 2.124 Å in 8a is very similar to the
W-O distance found in [WH3(OPh)(PMe3)4] (2.129 Å).29
The C-O distances of the ligands, which average 1.34
Å in all of the complexes, are typical of chelated fully
reduced catecholates, which have C-O lengths of about
1.35 Å with little variation.30 The C-C bond distances
of the catecholate ring average 1.391 Å in 7a and 1.390
Å in 7d , which are also comparable to the C-C
distances in typical molybdenum-catecholate com-
plexes.24a,b The bite angles at the metal formed by the
chelating ligand are 76.2° in 7a and 76.0° in 7d , and
they compare well with the values found in [{Mo(O2C6-
Cl4)3}2] and [Mo(O2C14H8)3] (75-77°).30b,31 The bite
angle O-W-O in 8a is 75.7°, and this value is slightly
smaller than that of 7a .
F igu r e 2. ORTEP drawing of the molecular structure of
7a , with the atom-numbering scheme.
of the molecule, although the hydride signal is a quasi-
quintet. The hydride ligands seem to exchange their
positions within the complex fast enough to be equiva-
lent on the NMR time scale.
In conclusion, the results obtained show that photo-
chemical or thermal reaction of [MoH4(dppe)2] or trans-
[W(N2)2(dppe)2] with N-alkylamides R1NHCOR2 gives
Formation of 7 may be accounted for by a reaction
path similar to that considered for the aliphatic alcohols
(Scheme 3).
(26) Hills, A.; Hughes, D. L.; Pombeiro, A. J . L.; Richards, R. L. J .
Organomet. Chem. 1990, 398, C15.
(27) Dadkhah, H.; Hughes, D. L.; Kashef, N.; Pombeiro, A. J . L.;
Richards, R. L. J . Organomet. Chem. 1983, 255, C1.
(28) Pombeiro, A. J . L.; Hills, A.; Hughes, D. L.; Richards, R. L. Acta
Crystallogr. 1995, C51, 23.
(29) Chiu, K. W.; J ones, R. A.; Wilkinson, G.; Galas, A. M. R.;
Hursthouse, M. B.; Malik, K. M. A. J . Chem. Soc., Dalton Trans. 1981,
1024.
(30) (a) Buchanan, R. M.; Kesel, S. L.; Downs, H. H.; Pierpont, C.
G.; Hendrickson, D. N. J . Am. Chem. Soc. 1978, 100, 7894. (b)
Pierpont, C. G.; Downs, H. H. J . Am. Chem. Soc. 1975, 97, 2123.
(31) Pierpont, C. G.; Buchanan, R. M. J . Am. Chem. Soc. 1975, 97,
4912.
Cr ysta l Str u ctu r e Deter m in a tion of Com p lexes
7a ,d a n d 8a . Good prismatic single crystals of the
catecholato complexes 7a ,d and 8a suitable for X-ray
analysis were obtained by crystallization from toluene-
hexane. A summary of the crystallographic data is
given in Table 8, and the selected bond lengths and
angles are given in Tables 9-11. ORTEP drawings are
shown in Figures 2-4. The molecular structures of 7a ,d
and 8a , which are monomeric in the solid state, are well-
resolved, and the hydride atoms are clearly identified.

η2-N-Acylamido-N,O Hydrido Complexes of Mo and W
Organometallics, Vol. 15, No. 22, 1996 4869
Ta ble 7. 1H a n d 13C NMR Da ta for [MH2(Ca t)(d p p e)2] (M ) Mo (7), W (8))
compd
1H NMRa
13C NMRb
7a
8a
7b
-2.54 (qnt, MoH, J HP ) 48.7 Hz, 2H), 6.33 (m, C6H4, 4H)
0.23 (qnt, WH, J HP ) 42.0 Hz, 2H), 6.33 (m, C6H4, 4H)
-2.60 (qnt, MoH, J HP ) 48.5 Hz, 2H), 5.90-6.20 (C6H3, 3H),
2.31 (s, C6H3CH3, 3H)
161.9, 114.6, 114.9 (C6H4)
161.0, 114.7, 115.0 (C6H4)
161.7, 159.7, 122.1, 116.1, 114.7, 113.9 (C6H3), 21.5 (C6H5CH3)
8b
7c
8c
7d
8d
0.16 (qnt, WH, J HP ) 41.0 Hz, 2H), 5.90-6.20 (C6H3, 3H),
160.9, 158.7, 122.3, 116.1, 114.8, 114.1 (C6H3), 21.3 (C6H3CH3)
2.32 (s, C6H3CH3, 3H)
-2.59 (qnt, MoH, J HP ) 48.6 Hz, 2H), 6.20 (m, C6H3, 3H),
1.47 (s, C(CH3)3, 9H)
0.16 (qnt, WH, J HP ) 41.2 Hz, 2H), 6.20 (m, C6H3, 3H),
1.48 (s, C(CH3)3, 9H)
-2.66 (tt, MoH, J HP ) 26.5, 70.2 Hz, 2H), 1.18 (t, OCH2CH3,
J ) 7.3 Hz, 3H), 4.4 (m, OCH2CH3, 2H)
0.2 (br, WH, 2H), 1.12 (t, OCH2CH3, J ) 7.3 Hz, 3H),
4.4 (m, OCH2CH3, 2H)
161.0, 159.3, 135.9, 116.6, 113.6, 112.1 (C6H3), 33.9 (C(CH3)3),
32.8 (C(CH3)3)
160.1, 158.5, 136.0, 113.7, 112.1, 110.7 (C6H3), 33.8 (C(CH3)3),
32.8 (C(CH3)3)
168.3, 161.5, 119.2, 116.3, 116.0, 114.0 (C6H3), 161.4 (CO),
59.1 (OCH2CH3), 15.0 (OCH2CH3)
168.1, 166.8, 119.1, 116.4, 116.0, 114.1 (C6H3), 160.7 (CO),
59.1 (OCH2CH3), 15.0 (OCH2CH3)
7e
8e
-2.67 (qnt, MoH, J HP ) 49.2 Hz, 2H)
0.14 (qnt, WH, J HP ) 41.2 Hz, 2H)
163.0, 125.7, 124.3, 119.4, 108.5 (C10H6)
163.0, 125.7, 124.4, 119.7, 108.7 (C10H6)
a
b
Conditions: C6D6, in ppm, 293 K, 270 MHz, TMS reference. Conditions: C6D6, in ppm, 293 K, 67.8 MHz, TMS reference.
Ta ble 8. Cr ysta llogr a p h ic Da ta for 7a ,d a n d 8a
C58H54O2P4Mo (7a )
C61H58O4P4Mo (7d )
C58H54O2P4W (8a )
1090.81
fw
1002.90
1074.96
cryst syst
space group
a, Å
orthorhombic
P212121 (No. 19)
20.544(5)
monoclinic
P21/n (No. 14)
12.23(1)
orthorhombic
P212121 (No. 19)
20.469(3)
b, Å
22.884(4)
27.37(1)
22.900(2)
c, Å
10.741(6)
5049(2)
4
4.28
2080.00
1.319
16.18(1)
5402(6)
4
4.07
2232.00
1.322
0.50 × 0.20 × 0.20
29.6-29.9
32, 16, 8
10.752(3)
5039(1)
4
24.63
2208.00
1.437
V, Å3
Z
µ, cm-1
F(000)
F
calcd, g cm-3
cryst size, mm
0.35 × 0.30 × 0.24
0.40 × 0.30 × 0.26
2θ range, deg
25.1-29.9
29.8-30.0
scan rate, deg min-1
no. of rflns measd
no. of obsd reflns (I > 3.00σ(I))
final R indicesa,b
16.0
4979
4046
16.0
4970
4399
10220
5153
R1 ) 0.031, wR2 ) 0.043
R1 ) 0.034, wR2 ) 0.049
R1 ) 0.046, wR2 ) 0.063
R1 ) 0.027, wR2 ) 0.034
R1 ) 0.055, wR2 ) 0.081
R indices (all data)
a
b
2
R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) [∑w(|Fo| - |Fc|)2/∑w|Fo| ]1/2
.
Ta ble 9. In ter a tom ic Dista n ces (Å) a n d An gles
(d eg) for 7a
Ta ble 10. In ter a tom ic Dista n ces (Å) a n d An gles
(d eg) for 7d
Distances
Distances
Mo(1)-P(1)
Mo(1)-P(3)
Mo(1)-O(1)
O(1)-C(1)
2.489(1)
2.466(1)
2.126(3)
1.336(6)
1.377(7)
1.376(10)
1.393(8)
1.65
Mo(1)-P(2)
Mo(1)-P(4)
Mo(1)-O(2)
O(2)-C(6)
2.452(1)
2.511(2)
2.134(4)
1.345(6)
1.401(9)
1.389(8)
1.410(8)
1.51
Mo(1)-P(1)
Mo(1)-P(3)
Mo(1)-O(1)
O(1)-C(53)
C(53)-C(54)
C(55)-C(56)
C(57)-C(58)
C(56)-C(59)
C(59)-O(4)
Mo(1)-H(0a)
2.468(2)
2.508(2)
2.127(4)
1.326(7)
1.391(10)
1.46(1)
1.34(1)
1.45(1)
1.31(1)
1.54
Mo(1)-P(2)
Mo(1)-P(4)
Mo(1)-O(2)
O(2)-C(54)
C(54)-C(55)
C(56)-C(57)
C(53)-C(58)
C(59)-O(3)
C(60)-O(4)
Mo(1)-H(0b)
2.506(2)
2.454(2)
2.137(4)
1.351(8)
1.401(10)
1.34(1)
1.408(9)
1.29(1)
1.50(2)
1.64
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
C(4)-C(5)
C(5)-C(6)
C(1)-C(6)
Mo(1)-H(1Ma)
Mo(1)-H(1Mb)
Angles
O(1)-Mo(1)-O(2)
O(1)-Mo(1)-P(2)
P(1)-Mo(1)-P(2)
C(1)-C(2)-C(3)
76.2(1) O(1)-Mo(1)-P(1) 91.8(1)
148.4(1) O(1)-Mo(1)-P(3) 73.9(1)
81.53(5) P(3)-Mo(1)-P(4) 80.78(5)
120.0(6) O(1)-C(1)-C(6) 116.9(5)
Angles
O(1)-Mo(1)-O(2)
P(1)-Mo(1)-O(2)
P(1)-Mo(1)-P(2)
C(53)-C(58)-C(57) 121.6(9) O(1)-C(53)-C(54)
O(3)-C(59)-C(56) 121(1)
76.0(2) P(2)-Mo(1)-O(2)
150.5(1) P(4)-Mo(1)-O(2)
80.57(5) P(3)-Mo(1)-P(4)
89.1(1)
73.6(1)
80.96(7)
117.3(6)
H(1Ma)-Mo(1)-H(1Mb) 68.8
H(0a)-Mo(1)-H(0b) 64.5
the seven-coordinate complexes [MH{N(R1)COR2-N,O}-
(dppe)2] (M ) Mo (2), W (3)) as a result of oxidative
addition involving amide N-H bond cleavage, and the
resulting highly reactive N-acylamido complexes 2a and
3a react readily with alcohols and catechols to give
alkoxo- and catecholato-hydrido complexes. The reac-
tions apparently proceed via a coordinatively unsatur-
ated 16e intermediate, which is formed upon release of
the N-acylamide. The intriguing chemistries of com-
plexes 2 and 3 are being further developed in our
laboratories with special reference to the synthesis of
novel molybdenum and tungsten complexes. Further
studies on the reactivity of dihydrido dimethoxo com-
plexes such as [MH2(OMe)2(dppe)2] are also in progress.
Exp er im en ta l Section
Gen er a l Com m en ts. All reactions were carried out under
purified argon (except where otherwise indicated) using stan-
dard Schlenk techniques. Commercially available reagent
grade chemicals were used as such without any further
purification. All solvents were dried by standard methods and
were stored under argon. [MoH4(dppe)2] (1) and trans-[W(N2)2-
(dppe)2] were prepared by published procedures.3,32 UV-

4870 Organometallics, Vol. 15, No. 22, 1996
Minato et al.
Ta ble 11. In ter a tom ic Dista n ces (Å) a n d An gles
(d eg) for 8a
for 3 h to give a red solution. The release of H2 (0.77 mol per
mol of 1) was observed. Removal of the solvent from the
solution by a trap-to-trap method left a reddish brown solid
that was dissolved in benzene (3 mL). To the resulting solution
was added hexane (15 mL), and cooling the solution at 6 °C
for 12 h gave a yellow precipitate of unreacted 1. From the
supernatant solution, the solvent was evaporated to dryness
under reduced pressure, and washing the residue with hexane
gave 2a in 26% yield. Similar results were obtained when 1
reacted with CH3NHCOCH3 at 110 °C in toluene for 5 h.
These procedures are also applicable to the syntheses of the
other molybdenum or the tungsten complexes. Experiments
listed in Table 1 were carried out under essentially the same
conditions. Complexes 2 and 3 are soluble in benzene, toluene,
THF, and diethyl ether and are moderately stable to air in
the solid state but deteriorate rapidly with air in solution.
Analytical data and spectroscopic properties of complexes 2
and 3 are given in Tables 2 and 3.
Distances
W(1)-P(1)
2.482(2)
2.462(2)
2.116(4)
1.348(8)
1.378(10)
1.37(1)
1.39(1)
1.70
W(1)-P(2)
2.452(2)
2.499(2)
2.132(5)
1.332(8)
1.41(1)
1.39(1)
1.42(1)
1.80
W(1)-P(3)
W(1)-P(4)
W(1)-O(1)
O(1)-C(53)
C(53)-C(54)
C(55)-C(56)
C(57)-C(58)
W(1)-H(58)
W(1)-O(2)
O(2)-C(58)
C(54)-C(55)
C(56)-C(57)
C(53)-C(58)
W(1)-H(59)
Angles
O(1)-W(1)-O(2)
P(2)-W(1)-O(1)
P(1)-W(1)-P(2)
75.7(2)
147.7(1)
P(1)-W(1)-O(1)
90.9(1)
73.5(1)
80.59(6)
P(3)-W(1)-O(1)
81.36(6) P(3)-W(1)-P(4)
C(56)-C(57)-C(58) 120.2(8)
H(58)-W(1)-H(59) 70.0
O(1)-C(53)-C(58) 116.2(6)
Syn th esis of th e Alk oxo Com p lexes. [MoH2(OMe)2-
(d p p e)2] (4). A suspension of 2a (0.3057 g, 0.45 mmol) in 20
mL of methanol was stirred at ambient temperature for 12 h,
during which time the dark red complex 2a changed to a
yellowish powder. The supernatant solution was removed with
a bridge filter, and the residue thus obtained was washed
successively with methanol, hexane, and diethyl ether. The
resulting yellowish solid was dried under vacuum. Anal.
Found: C, 67.07; H, 5.93. Calcd for C54H56O2P4: C, 67.78; H,
5.90. IR (KBr disk): ν(methyl C-H) 2805 cm-1, ν(Mo-H) 1800
cm-1, ν(C-O) 1095 cm-1
.
1H NMR (270 MHz, C6D5CD3): δ
2
3.10 (s, OCH3, 6H), -2.29 (qnt, J HP ) 34.6, 2H, Mo-H).
31P{1H} NMR (C6D5CD3): δ 71.3 (br, s). The analogous
tungsten complex [WH2(OMe)2(dppe)2] (5) is obtained when
complex 3a reacts with methanol at ambient temperature for
48 h (34%). The resulting complexes 4 and 5, which are soluble
in benzene and toluene, are moderately stable under an inert
atmosphere in the solid state. IR (KBr disk): ν(methyl C-H)
2825 cm-1, ν(W-H) 1860 cm-1
.
1H NMR (270 MHz, C6D5-
CD3): δ 3.05 (s, OCH3, 6H), -1.08 (br, m, 2H, W-H).
F igu r e 3. ORTEP drawing of the molecular structure of
7d , with the atom-numbering scheme.
[MoH2(OEt)2(d p p e)2] (6). A suspension of 2a (0.0851 g,
0.09 mmol) in 10 mL of ethanol was stirred at ambient
temperature for 96 h, during which time the dark red complex
2a changed to a yellowish powder. The supernatant solution
was removed with a bridge filter and the residue thus obtained
was washed successively with ethanol and pentane. The
resulting yellowish solid was dried under vacuum. Complex
6 is soluble in benzene and toluene but insoluble in hexane
and diethyl ether. IR (KBr disk): ν(Mo-H) 1805 cm-1
.
1H
NMR (270 MHz, C6D6): δ 3.40 (q, J ) 6.72 Hz, 4H, OCH2-
2
CH3), 0.95 (t, 6H, OCH2CH3), -3.66 (qnt, J HP ) 29.9 Hz, 2H,
Mo-H).
When this reaction was carried out at 60 °C, the carbonyl
complex cis-[Mo(CO)2(dppe)2]14 was obtained (62%).
Rea ction of 2a w ith 2-P r op a n ol. A suspension of 2a
(0.1481 g, 0.15 mmol) in 15 mL of 2-propanol was stirred under
reduced pressure at ambient temperature for 96 h, during
which time the dark red complex 2a changed to a yellowish
powder. The solvent was removed under vacuum, and the
residue was washed successively with hexane and diethyl
ether. The resulting light yellow product was dried under
vacuum. It was spectroscopically identical with [MoH4(dppe)2]
(1; 71%).
F igu r e 4. ORTEP drawing of the molecular structure of
8a , with the atom-numbering scheme.
Syn th esis of Ca tech ola to Com p lexes. A typical proce-
dure is as follows. A solution containing 2a and catechol in
toluene was stirred at ambient temperature under the condi-
tions given in Table 5. During the stirring, the solution
changed from dark red to black. The solvent was evaporated
from the resulting solution to dryness under reduced pressure.
The residue was washed successively with methanol and
hexane and dried under vacuum. These procedures are also
applicable to the syntheses of the other molybdenum or
tungsten complexes. Preparations, analytical data, and se-
visible light irradiation was performed by using a Riko 400-W
high-pressure mercury lamp and a Pyrex glass filter.
Syn th esis of th e N-Acyla m id o Com p lexes. A typical
procedure is as follows. A Pyrex Schlenk flask containing a
yellow solution of complex 1 (0.24 g, 0.27 mmol) and CH3-
NHCOCH3 (21 µL, 0.27 mmol) dissolved in benzene (27 mL)
was irradiated by light under vacuum at ambient temperature
(32) Archer, L. C.; George, T. A.; Nobel, M. E. J . Chem. Educ. 1981,
58, 727.

η2-N-Acylamido-N,O Hydrido Complexes of Mo and W
Organometallics, Vol. 15, No. 22, 1996 4871
lected spectroscopic data for all complexes are compiled in
Tables 5-7, respectively. Complexes 7 and 8 are soluble in
benzene, toluene, and THF but insoluble in hexane. Although
the complexes decompose in solution immediately under air,
the solids can be handled briefly in air.
Ack n ow led gm en t. We thank Dr. Y. Nakamura of
the Tokyo Institute of Technology for measuring the
NMR spectra. We also thank Mr. Masatoshi Ikeya, Mr.
Ikko Shirai, and Mr. Ko-ichiro Nagai of Yokohama
National University for preparing complex 3b. This
work was supported by a Grant-in-Aid for Scientific
Research on Priority Area (No. 05236104) and in part
by Grant-in-Aid for Scientific Research (B) (No. 07455354)
from the Ministry of Education, Science and Culture of
J apan.
X-r a y Cr ysta llogr a p h ic Stu d y of 7a ,d a n d 8a . Crystals
of complex 7a ,d and 8a suitable for X-ray crystallography were
grown in toluene-hexane at 10 °C, and crystals thus obtained
were mounted on a glass fiber. Measurements were made on
a Rigaku AFC7R (for 7a and 7d ) or a Rigaku AFC5R (for 8a )
diffractometer by using Mo KR radiation (λ ) 0.710 69 Å) for
data collection. The unit-cell parameters were determined by
least-squares fitting of 25 reflections for 7a , of 16 reflections
for 7d , and of 24 reflections for 8a with ranges 25.09° e 2θ e
29.89°, 29.57° e 2θ e 29.90°, and 29.81° e 2θ e 29.99°,
respectively. The parameters used during the collection of
diffraction data are given in Table 8. The structure was solved
and refined by using Fourier techniques.33 The non-hydrogen
atoms were refined anisotropically. Hydrogen atoms were
included but not refined.
Su p p or tin g In for m a tion Ava ila ble: Tables of fractional
atomic coordinates, anisotropic thermal factors, and all bond
distances and angles for 7a ,d and 8a (51 pages). Ordering
information is given on any current masthead page.
OM9603124
(33) Beurskens, P. T.; Admiraal, G.; Bosman, W. P.; Garcia-Granda,
S.; Gould, R. O.; Smits, J . M. M.; Smykalla, C. The DIRDIF Program
System; Technical Report of the Crystallography Laboratory; Univer-
sity of Nijmegen, Nijmegen, The Netherlands, 1992.