Synthesis and Characterization of Unsymmetrical (cis-(Phosphino-arsino)ethene)tetracarbonylmolybdenum Complexes: Hydroarsination Reactions of (H3CC≡PPh2)Mo(CO)5 and [H2C=C=CH(DBP)]Mo(CO)5 and Hydrophosphination Reactions of (Ph2AsCH2C≡CH)Mo(CO)5

Article abstract of DOI:10.1021/ic9711170

The base-catalyzed hydroarsination reactions of (H₃CC≡CPPh₂)Mo(CO)₅ and [H₂C=C=CH(DBP)]Mo(CO)₅ (DBP = dibenzophosphole) give several different products as a function of reaction conditions. These products have been characterized by elemental analyses, physical properties, ¹H, ¹³C{¹H}, and ³¹P{¹H} NMR spectroscopy, and, in two cases, X-ray crystallography.

Full text of DOI:10.1021/ic9711170

Inorg. Chem. 1998, 37, 1105-1111
1105
Synthesis and Characterization of Unsymmetrical
(cis-(Phosphino-arsino)ethene)tetracarbonylmolybdenum Complexes: Hydroarsination
Reactions of (H3CCtCPPh2)Mo(CO)5 and [H2CdCdCH(DBP)]Mo(CO)5 and
Hydrophosphination Reactions of (Ph2AsCH2CtCH)Mo(CO)5
Kalyani Maitra, Vincent J. Catalano, Jerry Clark III, and John H. Nelson*
Department of Chemistry/216, University of NevadasReno, Reno, Nevada 89557-0020
ReceiVed August 29, 1997
The base-catalyzed hydroarsination reactions of (H3CCtCPPh2)Mo(CO)5 and [H2CdCdCH(DBP)]Mo(CO)5 (DBP
) dibenzophosphole) give several different products as a function of reaction conditions. These products have
1
been characterized by elemental analyses, physical properties, H, 13C{1H}, and 31P{1H} NMR spectroscopy,
and, in two cases, X-ray crystallography.
Introduction
Scheme 1
Secondary phosphines are well-known to undergo Michael
type additions (hydrophosphination) to coordinated phosphi-
noalkenes and -alkynes to produce cis-diphosphine complexes
stereospecifically.1 Such addition reactions may provide an
efficient route for the syntheses of unsymmetrical, rigid,
chelating diphosphine ligands which have potential applications
in the area of asymmetric catalysis.2 Previously, as part of
extensive studies into reactions of this type, we reported the
base-catalyzed additions of the coordinated secondary phos-
phine/phosphole (1a,b) to tertiary phosphinoalkyne complexes
(2a,b) that resulted in the formation of mixed unsymmetrical
rigid chelate cis-diphosphinoethene ligands of the types A,3 B,4
C,5 and D5 (Scheme 1).
To further explore the scope of these reactions we have
studied the base-promoted additions of the activated alkene and
alkyne complexes 2a′ and 2b′′ toward hydroarsination with
diphenylarsine to form the unsymmetrical rigid mixed-arsino-
phosphino/phospholyl ligands analogous to B and D. We also
studied the aptitude of the (diphenylarsino)alkyne complex (Ph2-
AsCH2CtCH)Mo(CO)5, G, to undergo hydrophosphination
with a free and coordinated secondary phosphine and a
coordinated secondary phosphole, and the results are reported
herein.
Results and Discussion
(1) Carty, A. J.; Johnson, D. K.; Jacobson, S. E. J. Am. Chem. Soc. 1979,
101, 5612.
We have earlier reported4 the isomerization of the phosphi-
noalkyne complex 2b in the presence of base to produce a
mixture of the three isomers 2b, 2b′, and 2b′′ (propargyl, allenyl,
and propynyl), respectively, in solution (Scheme 2). These
isomers were separated by column chromatography on silica
gel. In a similar manner we were able to obtain the analogous
DBP allenyl complex 2a′ (DBP ) dibenzophosphole). Com-
plexes 2a′ and 2b′′ were separately reacted with free diphenyl
arsine (Schemes 3 and 4, respectively) under the same reaction
conditions.
(2) See for example: (a) Kagan, H. B.; Dang, T. P. J. Am. Chem. Soc.
1972, 94, 4, 6429. (b) Achiwa, K. J. Am. Chem. Soc. 1976, 98, 8265.
(c) Wilson, M. E.; Nuzzo, R. G.; Whitesides, G. M. J. Am. Chem.
Soc. 1978, 100, 2269. (d) Treichel, P. M.; Wong, W. L.; Calabrese, J.
C. J. Organomet. Chem. 1978, 159, C20. (e) Brunie, S.; Mazan, J.;
Langlois, N.; Kagan, H. B. J. Organomet. Chem. 1976, 114, 225. (f)
Brown, J. M.; Chaloner, P. A. J. Chem. Soc., Chem. Commun. 1978,
321. (g) Sanger, A. R.; Tan, K. G. Inorg. Chim. Acta 1978, 31, L439.
(h) Brunner, H., Zettlmeier, W., Eds. Handbook Of EnantioselectiVe
Catalysis; VCH: Weinheim, Germany, 1993; Vol. II.
(3) Wilson, W. L.; Alcock, N. W.; Alyea, E. C.; Song, S.; Nelson, J. H.
Bull. Soc. Chim. Fr. 1993, 130, 673.
(4) Maitra, K.; Catalano, V. J.; Nelson, J. H. J. Organomet. Chem. 1997,
529, 409.
(5) Maitra, K.; Catalano, V. J.; Nelson, J. H. Bull. Chim. Soc. Fr. 1997,
5, 471.
The hydroarsination reaction of 2b′′ with Ph2AsH, in the
presence of potassium tert-butoxide in refluxing diglyme
S0020-1669(97)01117-8 CCC: $15.00 © 1998 American Chemical Society
Published on Web 02/07/1998

1106 Inorganic Chemistry, Vol. 37, No. 5, 1998
Maitra et al.
Scheme 2
Scheme 5
Scheme 3
the internal vinyl fuctional group of 2a′ will produce the
dangling arsine complex J, which may undergo base promoted
Scheme 4
[1,3] hydrogen migration to produce any of the geometrical
isomers of H. Alternatively, the driving force of chelation may
also cause the intermediate J to form the five-membered chelate
ring following the elimination of a CO molecule to produce
the exo methylene complex K. The latter may subsequently
undergo the [1,3] hydrogen shift to form the thermodynamically
more stable complex F. Although we have not been able to
identify the intermediates J and K for this particular reaction,
we have earlier reported the formation of analogous dimolyb-
denum diphosphine, diphosphole, and mixed phosphine-
phosphole complexes obtained as products of similar hydro-
phosphination reactions.4,5 The formation of the cis-diphosphole
complex I in a minor amount indicates that some ligand
dissociation followed by the substitution of a CO unit may occur
to form the cis-bis(phosphole) intermediate L, which then
rapidly undergoes the hydroarsination reaction at the terminal
vinyl group in the Markovnikov sense to give the resultant cis-
bis(cis-DBP-As) complex I. It may also be argued that the
hydrophosphination reaction precedes the formation of the cis-
bis(phosphole) intermediate, in which case H is formed first,
and then two such molecules of H condense to form I following
the elimination of a unit of Mo(CO)6. The latter is more likely
as we have isolated H from the product mixture. A suggested
mechanistic pathway for the formation of I is shown in Scheme
5.
From our several attempts to synthesize the secondary arsine
complex Ph2AsHMo(CO)5 by the literature procedure designed
to prepare analogous secondary phosphine complexes,7 we found
the former to be highly unstable. In contrast, we were able to
synthesize the stable diphenyl tertiary arsinoalkyne complex G
[(Ph2AsCH2CtCH)Mo(CO)5] in 57% yield (see Experimental
Section) by following the same synthetic route.7 We therefore
attempted the hydrophoshination reactions of G separately with
the free secondary phosphine (Ph2PH) and the coordinated
phosphine in complex 1b. It was observed that, for both of
these reaction systems, ligand displacement occurred resulting
produced the chelate complex E as the major isolated product
along with the formation of the red bridged arsenide complex
[Ph2AsMo(CO)4]2. Purification by flash chromatography on
silica gel followed by recrystallization from a 1:1 mixture of
dichloromethane and methanol produced yellow orange crystals
of E in 46% yield. Base-promoted addition of the As-H bond
across the CtC triple bond in 2b′′ concomitant with the
formation of the five-membered chelate ring following the
elimination of a CO unit results in the formation of E.
Hydroarsinations of activated alkenes and alkynes have been
reported by others.6
Similarly, the reaction of 2a′ with Ph2AsH produces the
chelate complex F as the major product along with the formation
of complexes H and I in minor amounts (Scheme 4). The mixed
cis-As-P complex H is the result of the direct addition of the
As-H bond (such that the As and P units are cis oriented) across
the terminal vinyl function of complex 2a′ in a Markovnikov
sense. Addition at the same position may also occur in the same
manner with the P and As units being oriented trans to each
other and form the trans geometrical isomer. The rigid cis
isomer H having the dangling arsine arm has the favorable
geometry as opposed to the trans product and can therefore
spontaneously eliminate a molecule of CO to form the five-
membered chelate ring complex F. So far we have not been
able to identify or detect the trans mixed arsine-phospholyl
geometrical isomer of H in the product mixture. Analogous
dimolybdenum trans-diphosphine and mixed phosphole-phos-
phine complexes have been reported earlier.4,5 In a similar way,
the addition of the As-H bond in the Markovnikov sense across
(6) (a) Ma¨rkl, G.; Baier, H.; Liebl, R. Synthesis 1997, 842. (b) Chi, P. B.;
Kober, F. Z. Anorg. Allg. Chem. 1983, 501, 89. (c) Berger, H.-O.;
No¨th, H. J. Organomet. Chem. 1983, 250, 33.
(7) Maitra, K.; Wilson, W. L.; Jemin, M. M.; Yeung, C.; Rader, W. S.;
Redwine, K. D.; Striplin, D. P.; Catalano, V. J.; Nelson, J. H. Synth.
React. Inorg. Met.-Org. Chem. 1996, 26 (6), 967.

((Phosphino-arsino)ethene)Mo(CO)4 Complexes
Inorganic Chemistry, Vol. 37, No. 5, 1998 1107
in the formation of a variety of products which made complete
separation and characterization of all the complexes in the
reaction mixture a difficult and complicated process. From the
reaction of G with Ph2PH we isolated the chelate diphosphine
complex B4 as the major product. This indicates that the
propargyl unit of G somehow underwent complete dissociation
following its reaction with Ph2PH present in solution to produce
complex 2b. Complex 2b subsequently underwent the hydro-
phosphination reaction with Ph2PH to produce B. Similarly,
the reaction of G with 1b produced the expected mixed-arsine-
phosphine exo methylene chelate complex M along with the
M each display a single resonance at δ 55.03, 51.95, and 55.34
ppm, respectively, in the region expected for Mo(0) com-
plexes.4,5 The large downfield shifts for the phosphorus nuclei
in each case is consistent with the formation of the five-
membered chelate ring.9 The 13C{1H} NMR spectra for these
chelate complexes display two distinct sets of resonances for
each of the mutually cis equatorial carbonyl carbons, and the
most downfield resonance corresponds to the carbonyl group
2
trans to the arsino unit. The larger J(PC) value corresponds
to the carbonyl carbon trans to the phosphorus atom. The two
mutually trans carbonyl carbons are chemical shift equivalent
and appear most upfield as a doublet due to coupling to the cis
phosphorus atom. For complex N this pattern simplifies and
three resonances are observed as singlets, two for each of the
equatorial and another upfield one for the pair of axial carbonyls.
1
The H NMR spectra of E and F each display the presence
of one vinyl proton resonance coupled to the geminal phos-
phorus and vicinal CH3 group and as a result is a doublet of
quartets in each case. The CH3 resonance for both molecules,
having accidentally the same coupling constant values of 4J(PH)
) 4J(HH) ) 1.5 Hz, in both cases appears as an apparent triplet.
analogous diarsino exo methylene complex N and a minor
1
amount of O,4 as evidenced from the 31P{1H}, H, and 13C-
{1H} NMR spectroscopic data. As seen in the 1H NMR spectra,
these three complexes were present in the ratio M:N:O ) 5:3.1:
1. All three complexes were eluted in the same fractions during
the purification process by column chromatography, and we
were able to fractionally crystallize out M and N as a mixture
from a 1:1 dichloromethane/methanol solution. Although
several attempts to separate M and N by further chromatography
or crystallization remained unsuccessful, we were able to
completely characterize and establish the structures of both of
these complexes from the 1H (M, 61.5%; N, 38.5%; as seen in
the 1H NMR spectrum) and 13C{1H} NMR spectroscopic data.
The formation of N and B further confirms the fact that ligand
displacement reactions are a prominent feature of these systems.
The hydrophosphination reaction of G with 1a was also
attempted under the same reaction conditions. The 31P{1H}
NMR spectra of the crude product mixture showed resonances
for the two diphosphole chelate complexes A3 and R5 and other
decomposition products. Purification by column chromatog-
raphy using 5% benzene in hexane eluted a 1:1 mixture of A
and R in a few of the fractions. We did not isolate any mixed-
arsine-phosphole complexes from this reaction.
1
In the H NMR spectrum for complex M the resonances for
the two geminal protons are doublets of doublets due to large
magnititude coupling to phosphorus and coupling to each other
by 0.5 Hz. The methylene proton resonance for M appears as
a doublet due to coupling to phosphorus with a magnititude of
17.5 Hz. For the analogous diarsine complex N, the 1H NMR
spectrum further simplifies and exhibits only three singlets, two
in the vinylic region for the two geminal protons and one in
the aliphatic region for the two chemically equivalent methylene
protons. For this molecule we did not resolve any coupling
between the two geminal vinyl protons.
The 31P{1H} NMR spectrum for the pentacarbonyl complex
H displays a singlet at δ 14.27 ppm. The 13C{1H} NMR
spectrum for this mixed cis arsine-phospholyl complex in the
carbonyl region displays two sets of resonances of which the
more downfield has the higher magnititude coupling constant
and corresponds to the CO group trans to the phosphorus. The
other upfield resonance corresponds to the four carbonyl groups
cis to phosphorus. The 13C{1H} NMR spectrum also shows
resonances for the DBP and the phenyl ring carbons in the
aromatic region as expected (see Experimental Section). The
1H NMR spectrum for this complex shows the presence of a
vinylic proton coupled to the geminal phosphorus with a
The results of the various hydrophosphination reactions of
the activated arsinoalkyne complex G with secondary phos-
phines and phospholes led us to conclude that ligand substitution
or exchange is a predominant feature for these reaction systems,
and therefore, it determines the fate of the Michael addition
products formed. There is evidence for some (arsine)penta-
carbonylchromium complexes8 to undergo rapid ligand dis-
sociation followed by substitution with stronger nucleophiles,
such as a phosphine. We have encountered such ligand
dissociation followed by substitution reactions in the case of
mixed-phosphine-phosphole complexes.5 In contrast, the hy-
droarsination reactions of the phosphinoalkyne and phospholyl-
alleneyl complexes 2b′′ and 2a′, respectively, with the free
secondary arsine gave clean products, and no ligand exchange
products were observed in any of these cases. Most likely the
free secondary diphenyl arsine molecule acts as a stronger
nucleophile toward the unsaturated acetylinic and alleneyl bonds
in 2b′′ and 2a′, respectively, resulting in the rapid formation of
the Michael addition product followed by chelation.
2
magnititude of J(PH) ) 35.5 Hz and also coupled to the cis
CH3 protons with a magnitude of 1.5 Hz. These data are in
agreement with other reported values for analogous cis chelate
complexes3-5 and therefore support the cis orientation of the
CH3 and vinyl proton unit with respect to each other and hence
the proposed structure.
The 31P{1H} NMR spectrum for I shows a single resonance
at δ 18.29 ppm for the two equivalent phosphorus nuclei present
1
in this molecule. The H and 13C{1H} NMR spectra are both
second order as expected for an (R3P)2Mo(CO)4 complex.10 The
2
value of J(PP) is typical for a cis-(R3P)2Mo(CO)4 complex.11
4
The value of J(PH) ∼ 2.0 Hz suggests that the phosphorus
and CH3 are mutually trans.4,5,7 These data support the proposed
structural assignment for I.
For the diphenylarsine pentacarbonyl complex G the meth-
1
ylene resonance in the H NMR spectrum is a doublet due to
1
31P{1H}, 13C{1H}, and H NMR Spectroscopy. The 31P-
(9) Garrou, P. E. Chem. ReV. (Washington, D.C.) 1981, 81, 229.
(10) (a) Redfield, D. A.; Cary, L. W.; Nelson, J. H. Inorg. Chem. 1975,
14, 50. (b) Jenkins, J. M.; Moss, J. R.; Shaw, B. L. J. Chem. Soc. A
1969, 2796.
{1H} NMR spectra for the rigid chelate complexes E, F, and
(8) Atwood, J. A.; Wovkulich, M. J.; Sonnenberger, D. C. Acc. Chem.
Res. 1983, 16, 6, 350.
(11) Verkade, J. C. Coord. Chem. ReV. 1972/73, 1, 1.

1108 Inorganic Chemistry, Vol. 37, No. 5, 1998
Maitra et al.
Figure 3. Structural drawing of G, showing the atom-numbering
scheme (40% probability ellipsoids). Hydrogen atoms have an arbitrary
radius of 0.1 Å.
Figure 1. Structural drawing of E, showing the atom-numbering
scheme (40% probability ellipsoids). Hydrogen atoms have an arbitrary
radius of 0.1 Å.
The bond angles C(1)#1-Mo(1)-As(1)#1, C(1)-Mo(1)-P(1)
are 171.7(2), 173.2(2)° and C(1)-Mo(1)-P(1), C(2)-Mo(1)-
As(1) are 172.6(2), 172.3(2)° for E and F, respectively,
signifying the trans orientation of the two equatorial cabonyl
groups with respect to the arsenic and phosphorus atoms in both
molecules. The bond angles C(2)-Mo(1)-C(3) for E and
C(3)-Mo(1)-C(4) for F are 176.3(4) and 174.9(2)°, respec-
tively, consistent with the mutual trans orientation of the two
axial carbonyls. The Mo-P bond distances are slightly shorter
than the Mo-As distances for both E and F (see Table 1) as
expected12 and are in very good agreement with those reported
for similar Mo(0) complexes.13 Notably, in both of these
molecules the C-O bond lengths of the two mutually trans
carbonyls are shorter than those of the two carbonyls trans to
the phosphine and arsine ligands (see Table 1), which may be
a result of the better donor ability of the latter groups. In
complex F the bond distances 1.318(7) and 1.504(7) Å for
C(5)-C(7) and C(5)-C(6) signify the presence of a double bond
and a single bond, respectively. Moreover, the C(7)-C(5)-
C(6) bond angle (124.4(6)°) confirms the presence of sp2
hybridization at C(15). Similarly, for E the bond distances
C(4′)-C(5) and C(4′)-C(4)#1 are 1.44(1) and 1.317(2) Å,
suggesting the presence of a double and a single bond,
respectively. For the pentacarbonyl complex G the geometry
at the metal center is a slightly distorted octahedron with the
angles around the metal atom ranging from 87.9(4) to 92.0-
(4)°. The metal-carbon bond trans to the arsine moiety is
slightly shorter than the other metal-carbon bonds, which may
be due to the better donor ability of the arsine ligand. The bond
distance Mo(1)-As(1) (2.5799(11) Å) lies in close agreement
with those reported for similar As-Mo bonds.13
Figure 2. Structural drawing of F, showing the atom-numbering
scheme (40% probability ellipsoids). Hydrogen atoms have been omitted
for clarity.
coupling to the alkyne hydrogen, and the latter in turn is a
quartet. The chemical shifts for the other protons in the
molecule lie in the expected regions. The 13C{1H} NMR
spectrum for this complex is simple, as all the resonances are
singlets. Two sets of resonances are observed for the five
carbonyl groups, and the most downfield one corresponds to
the cabonyl carbon trans to the arsenic atom, while the other
relatively upfield resonance is due to the four cis carbonyls.
The two alkyne resonances appear in the region typical for sp-
hybridized carbons. The NMR spectral data for all complexes
are fully consistent with the assigned structures.
Crystal Structure Analysis. X-ray crystal structures of
complexes E-G were obtained to gain conclusive support for
their structures. These structures are shown in Figures 1-3,
respectively. Selected bond distances and angles are listed in
Tables 1 and 2, respectively. All three complexes exist as
discrete molecules with no abnormal intermolecular contacts.
The molecular structure of E is disordered accross a mirror plane
that bisects the ethylenic double bond and passes through the
two axial carbonyl groups and the metal atom. Both E and F
have a distorted octahedral geometry at the metal center, and
this distortion may be attributed largely to the formation of the
five-membered chelate ring. The equatorial plane in each case
is formed by the two mutually cis oriented arsenic and
phosphorus atoms and the two carbonyl groups trans to them.
Experimental Section
1. Reagents and Physical Measurements. Caution: Arsenic
compounds are potentially hazardous and should be handled with due
care!
Commercially available, reagent grade chemicals were used unless
otherwise indicated. All experiments were performed under a dry
nitrogen atmosphere using standard Schlenk line techniques. (RPh2P)-
Mo(CO)5 and (RDBP)Mo(CO)5, where R ) H and -CH2CtCH, were
prepared by literature methods.7 Tetrahydrofuran was distilled under
nitrogen from sodium benzophenone ketyl, and diglyme was distilled
(12) Carty, A. J.; Taylor, N. J.; Coleman, A. W.; Lappert, M. F. J. Chem.
Soc., Chem. Commun. 1979, 639.
(13) Aroney, M. J.; Buys, I. E.; Davies, M. S.; Hambley, T. W. J. Chem.
Soc., Dalton Trans. 1994, 2827.

((Phosphino-arsino)ethene)Mo(CO)4 Complexes
Inorganic Chemistry, Vol. 37, No. 5, 1998 1109
complex G
Table 1. Bond Distances (Å) for Complexes E-G
complex Ea
complex F
Mo(1)-C(1)#1
Mo(1)-C(1)
Mo(1)-C(3)
Mo(1)-C(2)
Mo(1)-P(1)#1
Mo(1)-P(1)
Mo(1)-As(1)
Mo(1)-As(1)#1
O(1)-C(1)
1.938(8)
1.939(8)
1.990(10)
1.996(11)
2.4840(13)
2.4841(13)
2.5349(14)
2.5349(13)
1.139(8)
1.136(11)
1.131(10)
1.81(1)
Mo(1)-C(2)
Mo(1)-C(1)
Mo(1)-C(3)
Mo(1)-C(4)
Mo(1)-P(1)
1.974(6)
1.992(7)
2.015(7)
2.043(7)
2.468(2)
2.6003(9)
1.947(5)
1.952(6)
1.968(6)
1.816(6)
1.815(6)
1.830(6)
1.153(7)
1.153(6)
1.142(7)
1.141(7)
1.318(7)
1.504(7)
Mo(1)-C(1)
Mo(1)-C(5)
Mo(1)-C(3)
Mo(1)-C(2)
Mo(1)-C(4)
Mo(1)-As(1)
As(1)-C(9)
As(1)-C(15)
As(1)-C(6)
O(1)-C(1)
O(2)-C(2)
O(3)-C(3)
O(4)-C(4)
O(5)-C(5)
C(6)-C(7)
C(7)-C(8)
1.977(10)
2.014(9)
2.015(10)
2.024(10)
2.030(10)
2.5799(11)
1.949(7)
Mo(1)-As(1)
As(1)-C(20)
As(1)-C(26)
As(1)-C(5)
P(1)-C(7)
P(1)-C(8)
P(1)-C(19)
O(1)-C(1)
O(2)-C(2)
O(3)-C(3)
O(4)-C(4)
C(5)-C(7)
C(5)-C(6)
1.951(8)
1.963(8)
O(2)-C(2)
1.114(11)
1.120(10)
1.132(11)
1.105(11)
1.119(10)
1.435(12)
1.186(14)
O(3)-C(3)
As(1)-C(4')
C(4′)-C(4′)#1
C(4′)-C(5)
1.317(2)
1.44(1)
1.89(1)
P(1)-C(4)
3
a Atoms marked with a number symbol are related to their symmetry-equivalent atoms by the transformation x, -y + /2, z.
Table 2. Bond Angles (deg) for Complexes E-G
complex Ea
C(1)#1-Mo(1)-C(1)
complex F
C(2)-Mo(1)-C(1)
complex G
C(1)-Mo(1)-C(5)
92.3(4)
87.8(3)
87.8(3)
89.7(3)
89.7(3)
176.3(4)
93.9(2)
173.2(2)
89.7(2)
93.1(2)
95.5(2)
171.7(2)
89.9(2)
93.0(2)
177.4(7)
176.4(9)
174.6(9)
119.6(2)
120.2(2)
92.0(2)
86.1(2)
92.7(3)
89.2(2)
89.3(3)
174.9(2)
95.3(2)
172.6(2)
88.7(2)
90.0(2)
172.3(2)
94.1(2)
89.0(2)
95.5(2)
78.64(4)
124.4(6)
88.0(3)
92.0(4)
179.5(4)
90.6(4)
91.6(3)
88.9(4)
88.8(4)
91.6(3)
87.9(4)
176.7(4)
176.3(2)
89.8(2)
90.2(3)
92.3(3)
176.4(8)
177.4(8)
178.9(9)
177.3(9)
178.6(8)
176.0(12)
C(1)#1-Mo(1)-C(3)
C(1)-Mo(1)-C(3)
C(1)#1-Mo(1)-C(2)
C(1)-Mo(1)-C(2)
C(3)-Mo(1)-C(2)
C(1)#1-Mo(1)-P(1)
C(1)-Mo(1)-P(1)
C(3)-Mo(1)-P(1)
C(2)-Mo(1)-P(1)
C(1)-Mo(1)-As(1)#1
C(1)#1-Mo(1)-As(1)#1
C(3)-Mo(1)-As(1)#1
C(2)-Mo(1)-As(1)#1
O(1)-C(1)-Mo(1)
O(2)-C(2)-Mo(1)
O(3)-C(3)-Mo(1)
C(4)#1-C(4)-P(1)
C(4′)#1-C(4′)-As(1)
C(2)-Mo(1)-C(3)
C(1)-Mo(1)-C(3)
C(2)-Mo(1)-C(4)
C(1)-Mo(1)-C(4)
C(3)-Mo(1)-C(4)
C(2)-Mo(1)-P(1)
C(1)-Mo(1)-P(1)
C(3)-Mo(1)-P(1)
C(4)-Mo(1)-P(1)
C(2)-Mo(1)-As(1)
C(1)-Mo(1)-As(1)
C(3)-Mo(1)-As(1)
C(4)-Mo(1)-As(1)
P(1)-Mo(1)-As(1)
C(7)-C(5)-C(6)
C(1)-Mo(1)-C(3)
C(5)-Mo(1)-C(3)
C(1)-Mo(1)-C(2)
C(5)-Mo(1)-C(2)
C(3)-Mo(1)-C(2)
C(1)-Mo(1)-C(4)
C(5)-Mo(1)-C(4)
C(3)-Mo(1)-C(4)
C(2)-Mo(1)-C(4)
C(1)-Mo(1)-As(1)
C(5)-Mo(1)-As(1)
C(3)-Mo(1)-As(1)
C(2)-Mo(1)-As(1)
O(1)-C(1)-Mo(1)
O(2)-C(2)-Mo(1)
O(3)-C(3)-Mo(1)
O(4)-C(4)-Mo(1)
O(5)-C(5)-Mo(1)
C(8)-C(7)-C(6)
a See footnote a in Table 1.
under nitrogen over sodium. Silica gel for column chromatography
(grade 12, 28-200 mesh) was obtained from Aldrich. Melting points
were determined on a Mel-Temp apparatus and are uncorrected.
Elemental analyses were performed by Galbraith Laboratories, Knox-
ville, TN. Solution infrared spectra were obtained on a Perkin-Elmer
Paragon 1000 PC FT spectrometer in sealed CaF2 cells. 31P{1H}, 13C-
{1H}, and 1H NMR spectra were recorded at 121.66 (202.35), 75
(125.70), and 300 (499.86) MHz, respectively, on either a General
Electric GN-300 or Varian Unity Plus-500 spectrometer. Proton and
carbon chemical shifts are relative to internal Me4Si, and phosphorus
chemical shifts are relative to external PPh3 (δ(31P) ) -6.0 ppm); all
shifts to low field (high frequency) are positive.
may result.) The reaction mixture was stirred for 15 min, and then
4.32 g (16.36 mmol) of Mo(CO)6 was added under a N2 purge.
Effervescence was detected, and the solution turned bright red-orange.
The reaction mixture was stirred at ambient temperature for 1-2 h
until the effervescence ceased followed by the addition of 1.5 molar
equiv of propargyl chloride. The reaction mixture immediately paled
in color. The mixture was allowed to stir at ambient temperature for
about 30 min, followed by the addition of 100 mL of 1 M HCl and
100 mL of hexane. The contents of the reaction flask were then
transferred to a 1 L separatory funnel, and the aqueous layer was
removed and discarded. To the organic phase was added 50 mL of
ether, and the solution was washed with two 100 mL portions of 1 M
HCl followed by two 100 mL portions of H2O. The organic phase
was dried with anhydrous magnesium sulfate and filtered by suction
through 80 mL of silica gel covered with 2 cm of Celite in a 200 mL
fritted glass funnel. The silica gel was washed with 200 mL of ether,
and the combined solvents were removed from the filtrate by rotary
evaporation using a water bath that was initially at ambient temperature
and gradually heated to 95-100 °C; the flask containing the product
was left on the rotary evaporator until the unreacted Mo(CO)6 had
sublimed. The flask was allowed to cool and was removed from the
rotary evaporator. The crude product was purified by column chro-
2.1. Synthesis of (Ph2AsCH2CtCH)Mo(CO)5 (G). To a solution
of 5.0 g (16.33 mmol) of AsPh3 in 15 mL of freshly distilled
tetrahydrofuran was added 1.0 g (144.1 mmol) of lithium (cut into small
flat pieces) under a nitrogen atmosphere with stirring. After 15-20
min, when the solution became deep red, 240 mL of freshly distilled
THF was added, and the reaction mixture was stirred at ambient
temperature for 4 h. During this period, the color of the reaction
mixture intensified to a deep orange red. The excess lithium was
removed under a N2 purge and disposed of by cautiously reacting it
with approximately 300 mL of 95% ethanol. Then 0.73 g (5.44 mmol)
of anhydrous AlCl3 was added to the reaction mixture.14 (Caution!
The reaction of the AlCl3 with phenyllithium is Vigorous; white fumes
(14) Holland, S.; Mathey, F.; Fischer, J. Polyhedron 1986, 5, 1413.

1110 Inorganic Chemistry, Vol. 37, No. 5, 1998
Maitra et al.
2
matography on silica gel with hexane as eluant. The first few fractions
eluted some ureacted Mo(CO)6 followed by the elution of some ligand
oxides. About 4.7 g (9.32 mmol, 57.1%) of the diphenylpropargylarsine
complex (G) was recovered.
Co′), 131.64 (d, J(PC) ) 12.7, Hz, Co), 129.81 (s, Cp′), 129.74 (d,
4J(PC) ) 1.8 Hz, Cp), 129.00 (s, Cm′), 128.60 (d, J(PC) ) 9.4 Hz,
3
Cm), 21.28 (d, 3J(PC) ) 16.5 Hz, CH3). Anal. Calcd for C31H24-
MoAsO4P: C, 56.30; H, 3.62. Found: C, 56.44; H, 3.51
2.2. Base-Catalyzed Reaction of Diphenylarsine with 2b′′. To
a solution of 0.23 g (0.50 mmol) of 2b′′ in 75 mL of freshly distilled
diglyme was added an equimolar amount of diphenylarsine (0.2 mL)
by means of a syringe under nitrogen, and the mixture was stirred for
3-4 min. A catalytic amount of potassium tert-butoxide (0.005 g)
was added to this reaction mixture, and it was allowed to reflux for 1
h under an atmosphere of nitrogen with stirring. The solvent was
removed by vacuum distillation while warming the reaction vessel on
a hot water bath. The resulting yellow orange oil was dissolved in
methylene chloride and washed with 2 × 50 mL of 1 M HCl and 50
mL of water. The organic layer was dried with magnesium sulfate
and filtered through a 1 cm thick silica bed layered with 0.5 cm of
Celite. The Celite-silica bed was further washed with another 20 mL
of dichloromethane to wash out all the products. The volume of the
combined filtrates was reduced to 15-20 mL on a rotary evaporator.
To this was added an equal volume of methanol, and the resulting
mixture was allowed to stand at -20 °C for 8 h whereby pale orange
yellow crystals of E (0.15 g, 0.23 mmol, 46%) separated out.
2.3. Base-Catalyzed Reaction of Diphenylarsine with 2a′. To a
solution of 1.24 g (2.70 mmol) of 2a′ in 150 mL of freshly distilled
diglyme was added 0.62 g (2.70 mmol) of diphenylarsine by means of
a syringe under a nitrogen atmosphere with stirring. This was followed
by the addition of 0.02 g of potassium tert-butoxide. The resultant
solution was refluxed for 4.5 h. The solvent was removed by vacuum
distillation while warming the reaction vessel on a hot water bath. The
oily brown crude product mixture was purified by column chromatog-
raphy on silica gel using 10% benzene in hexane as the eluant. The
concentration of benzene in the eluant was gradually increased. The
first few fractions eluted some ligand oxides followed by the elution
of 0.14 g (0.20 mmol, 7.4%) of complex H. The next few fractions
eluted the chelate product F which on recrystallization from 1:1
dicholoromethane/methanol solution gave pale yellow to almost color-
less crystals of pure F (1.14 g, 1.73 mmol, 64%). Last, 0.15 g of
complex I (0.13 mmol, 5.0%) was eluted from the column as a bright
yellow band.
.
F: Pale yellow solid. Mp: >190 °C (dec). IR (CH2Cl2): νCO (cm-1
)
2024 (m), 1928 (sh), 1908 (s), 1898 (sh). 31P{1H} NMR (CDCl3, 121.66
MHz): δ 51.95. 1H NMR (CDCl3, 499.86 MHz): δ 7.96-7.38 (m,
18H, aromatic H’s), 6.45 (dq, 2J(PH) ) 8.0 Hz, 4J(HH) ) 1.5 Hz, 1H,
4
4
CH3CdCH), 2.17 (apparent t, J(PH) ) J(HH) ) 1.5 Hz, 3H, CH3).
13C{1H} NMR (CDCl3, 125.70 MHz): δ 216.45 (d, 2J(PC) ) 7.7 Hz,
2
2
COeq,b′), 215.86 (d, J(PC) ) 24.9 Hz, COeq,b), 209.06 (d, J(PC) )
2
9.1 Hz, 2COax), 159.00 (d, J(PC) ) 32.3 Hz, CdCCH3), 142.69 (d,
2J(PC) ) 7.8 Hz, Câ), 140.26 (d, J(PC) ) 31.4 Hz, CdCH), 139.45
1
(d, 1J(PC) ) 42.2 Hz, CR), 136.70 (d, 3J(PC) ) 3.5 Hz, Ci), 132.12 (s,
2
2
Co), 130.69 (d, J(PC) ) 1.4 Hz, C2), 130.27 (d, J(PC) ) 16.1 Hz,
C4), 129.97 (s, Cp), 129.14 (s, Cm), 128.56 (d, 3J(PC) ) 10.2 Hz, C3),
3
3
121.53 (d, J(PC) ) 4.9 Hz, C1), 20.94 (d, J(PC) ) 17.5 Hz, CH3).
Anal. Calcd for C31H22MoAsO4P: C, 56.40; H, 3.33. Found: C, 56.53;
H, 3.21.
G: Colorless solid. Mp: 56 °C. IR (CH2Cl2): νCO (cm-1) 2075
(w), 1990 (sh), 1949 (s, br). 1H NMR (CDCl3, 499.86 MHz): δ 7.44-
7.55 (m, 10H, Ph), 3.10 (d, 4J(HH) ) 3.0 Hz, 2H, CH2), 2.18 (t, 4J(HH)
) 3.0 Hz, 1H, CtCH). 13C{1H} NMR (CDCl3, 125.70 MHz): δ
210.21 (s, COtrans), 205.21 (s, 4COcis), 136.35 (s, Ci), 131.50 (s, Co),
130.20 (s, Cp), 129.07 (s, Cm), 78.10 (s, H2CCtC), 73.79 (s, tCH),
20.32 (s, CH2). Anal. Calcd for C20H13MoAsO5: C, 47.66; H, 2.58.
Found: C, 47.73; H, 2.49.
H: Pale yellow solid. Mp: 131-132 °C. IR (CH2Cl2): νCO (cm-1
)
2072 (w), 1988 (sh), 1946 (s, br). 31P{1H} NMR (CDCl3, 202.35
MHz): δ 14.27. 1H NMR (CDCl3, 499.86 MHz): δ 7.92-7.26 (m,
2
4
18H, aromatic H’s), 6.05 (dq, J(PH) ) 34.5 Hz, J(HH) ) 1.5 Hz,
4
4
1H, CH3CdCH), 1.60 (apparent t, J(PH) ) J(HH) ) 1.5 Hz, 3H,
CH3). 13C{1H} NMR (CDCl3, 125.70 MHz): δ 209.56 (d, J(PC) )
2
2.4. Base-Catalyzed Reaction of G with 1b. To a solution of
1.66 g (3.3 mmol) of G and 1.39 g (3.3 mmol) of 1b in 170 mL of
freshly distilled diglyme was added a catalytic amount of potassium
tert-butoxide (0.025 g), and the mixture was refluxed for 3.5 h under
an atmosphere of nitrogen with stirring. The color of the solution turned
deep reddish brown. The solvent was removed by vacuum distillation.
The residue was dissolved in a minimum volume of dichloromethane,
and the organic layer was washed with 75 mL of 1 M HCl and 75 mL
of water. The organic layer was dried with magnesium sulfate and
filtered through a 1 cm thick Celite bed, followed by washing the bed
with some dichloromethane. The solvent was removed under vacuum,
and the reddish brown oily solid was purified by column chromatog-
raphy on silica gel using 5% benzene in hexane as the eluant. The
concentration of benzene in the eluant was gradually increased. The
first few fractions eluted some oxides of the ligands and some unreacted
starting material 1b and G. The later fractions eluted a mixture of
21.2 Hz, COtrans), 204.96 (d, 2J(PC) ) 8.8 Hz, 4COcis), 159.51 (d, 2J(PC)
2
) 11.2 Hz, HCdCCH3), 141.35 (d, J(PC) ) 8.7 Hz, Câ), 139.93 (d,
1J(PC) ) 41.7 Hz, CR), 137.72 (s, Ci), 133.70 (s, Co), 130.44 (d, 2J(PC)
) 1.5 Hz, C2), 129.94 (d, 2J(PC) ) 15.3 Hz, C4), 129.21 (d, 2J(PC) )
13.5 Hz, HCdCCH3), 128.95 (s, Cp), 128.88 (s, Cm), 128.60 (d, 3J(PC)
3
3
) 10.1 Hz, C3), 121.67 (d, J(PC) ) 5.0 Hz, C1), 20.50 (d, J(PC) )
10.4 Hz, CH3). Anal. Calcd for C32H22MoAsO5P: C, 55.84; H, 3.22.
Found: C, 55.63; H, 3.13.
I: Yellow solid. Mp: 82 °C. IR (CH2Cl2): νCO (cm-1) 2020 (w),
1950 (sh), 1922 (sh), 1906 (s), 1890 (sh). 31P{1H} NMR (CDCl3,
121.66 MHz): δ 18.29. 1H NMR (CDCl3, 499.86 MHz): δ 7.38-
2
4
6.98 (m, 36H, aromatic H’s of Ph, DBP), 5.84 (m, | J(PH) + J(PH)|
) 29.0 Hz, 2H, Ha), 1.48 (m, | J(PH) + 6J(PH)| ) 2.5 Hz, 6H, CH3).
4
13C{1H} NMR (CDCl3, 125.70 MHz): δ 213.50 (AXX′, 2J(PP) ) 21.2
Hz, 2J(PC) ) 22.5 Hz, 2J(P′C) ) -7.5 Hz, COeq), 209.28 (t, 2J(PC) )
1
9.6 Hz, COax), 154.08 (AXX′, | J(PC) + 4J(PC)| ) 9.2 Hz, Cb), 141.42
2
0.56 g of M, N, and O in the ratio 5:3.1:1 as determined from the H
2
4
2
NMR spectrum. Fractional crystallization from a 1:1 mixture of
dichloromethane and methanol gave 0.25 g of crystals of a mixture of
M and N. We were unable to further separate this mixture by either
column chromatography or fractional crystallization. Consequently,
they were only characterized as a mixture.
(AXX′, | J(PC) + J(PC)| ) 6.8 Hz, Câ), 139.02 (AXX′, J(PP) )
21.2 Hz, 1J(PC) ) 36.3 Hz, 3J(PC) ) 1.8 Hz, CR), 138.28 (s, Ci), 133.63
1
3
(s, Co), 132.70 (AXX′, | J(PC) + J(PC)| ) 18.6 Hz, HCdCCH3),
129.68 (AXX′, | J(PC) + 4J(PC)| ) 15.7 Hz, C4), 129.05 (s, C2), 128.58
2
3
5
(s, Cm), 128.52 (s, Cp), 127.84 (AXX′, | J(PC) + J(PC)| ) 9.8 Hz,
3
5
3.1. Characterization of the Complexes. E: Pale yellow solid.
Mp: >186 °C (dec). IR (CH2Cl2): νCO (cm-1) 2024 (m), 1910 (s),
1888 (sh). 31P{1H} NMR (CDCl3, 202.35 MHz): δ 55.03. 1H NMR
(CDCl3, 499.86 MHz): δ 7.60-7.39 (m, 20H, aromatic H’s), 7.36 (dq,
C3), 121.12 (AXX′, | J(PC) + J(PC)| ) 4.1 Hz, C1), 20.13 (AXX′,
| J(PC) + 5J(PC)| ) 9.9 Hz, CH3). Anal. Calcd for C58H44-
3
MoAs2O4P2: C, 62.61; H, 3.99. Found: C, 62.47; H, 3.82.
M: IR (CH2Cl2): νCO (cm-1) 2020 (w), 2010 (sh), 1911 (s, br),
1882 (sh). 31P{1H} NMR (CDCl3, 121.66 MHz): δ 55.34. 1H NMR
(CDCl3, 499.86 MHz): δ 7.3-7.6 (m, 20H, aromatic H’s), 5.80 (dd,
3J(PH) ) 24.0 Hz, 2J(HH) ) 0.5 Hz, 1H, Hb), 5.03 (dd, 2J(PH) ) 11.5
Hz, 2J(HH) ) 0.5 Hz, 1H, Ha), 3.15 (d, 2J(PH) ) 17.5 Hz, 2H, CH2).
13C{1H} NMR (CDCl3, 125.70 MHz): δ 217.24 (d, 2J(PC) ) 8.9 Hz,
4
2J(PH) ) 5.5 Hz, JHH ) 1.5 Hz, 1H, CH3CdCH), 2.34 (apparent t,
4J(PH) ) 4J(HH) ) 1.5 Hz, 3H, CH3). 13C{1H} NMR (CDCl3, 125.70
2
2
MHz): δ 218.20 (d, J(PC) ) 8.6 Hz, COeq,b′), 216.69 (d, J(PC) )
26.0 Hz, COeq,b), 208.69 (d, 2J(PC) ) 8.7 Hz, 2COax), 159.56 (d, 2J(PC)
) 32.2 Hz, CdCCH3), 139.54 (d, 1J(PC) ) 37.5 Hz, CdCH), 137.34
(d, 1J(PC) ) 40.0 Hz, Ci), 136.27 (d, 3J(PC) ) 3.4 Hz, Ci′), 132.05 (s,
2
2
COeq,b′), 216.68 (d, J(PC) ) 24.9 Hz, COeq,b), 209.58 (d, J(PC) )

((Phosphino-arsino)ethene)Mo(CO)4 Complexes
Inorganic Chemistry, Vol. 37, No. 5, 1998 1111
Table 3. Crystallographic Data for Complexes E-G
NMR (CDCl3, 125.70 MHz): δ 217.22 (s, COeq,b′), 216.92 (s, COeq,b),
209.16 (s, 2COax), 146.03 (s, CdCH2), 136.94 (s, Ci), 134.93 (s, Ci),
131.69 (s, 2Co), 129.85 (s, Cp), 129.82 (s, Cp), 128.95 (s, Cm), 128.93
(s, Cm), 125.35 (s, CdCH2), 35.86 (s, CH2).
complex
E
F
G
3.2. X-ray Data Collection and Processing. Pale yellow crystals
of G and F and yellow-orange crystals of E were grown by slow
diffusion of methanol into saturated solutions of methylene chloride
through an ethereal layer at -20 °C. Suitable crystals were mounted
on glass fibers and placed on a Siemens P4 diffractometer. Crystal
data and details of data collection for complexes E-G are given in
Table 3. Intensity data were taken in the ω-mode at 298 K with Mo
KR graphite-monochromated radiation (λ ) 0.710 73 Å). Three check
reflections monitored every 100 reflections showed random (<2%)
variation during the data collections. The data were corrected for
Lorentz, polarization effects, and absorption (using an empirical model
derived from azimuthal data collections). Scattering factors and
corrections for anomalous dispersion were taken from a standard
source.15 Calculations were performed with the Siemens SHELXTL
PLUS version 5.03 software package on a personal computer. The
structures were solved by direct methods. Anisotropic thermal
parameters were assigned to all non-hydrogen atoms. Hydrogen atoms
were refined at calculated positions with a riding model in which the
C-H vector was fixed at 0.96 Å.
chem
formula
fw
cryst system orthorhombic
space group Pnma
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
C31H24AsMoO4P C31H22AsMoO4P C20H13AsMoO5
662.33
660.32
triclinic
P1h
504.16
monoclinic
P21/n
17.192(2)
21.649(4)
7.7420(10)
90
90
90
11.2340(10)
11.5840(10)
12.4650(10)
62.770(10)
86.550(10)
77.270(10)
1405.4(2)
2
11.848(2)
13.006(3)
13.506(2)
90
95.191(12)
90
2881.5(7)
4
2072.7(7)
4
Fcalcd
1.527
1.560
1.616
(Mg/m3)
µ (mm-1
R1(F)a
)
1.684
1.726
2.243
0.0544
0.1215
1.040
0.0476
0.0877
1.015
0.0673
0.1691
1.030
wR2(F2)b
GOF
a R1(F) ) ∑||Fo| - |Fc||/Σ|Fo|. wR2(F2) ) [∑[w(Fo - Fc2)2]/
b
2
2
∑[w(Fo )2]]0.5
.
Acknowledgment. We are grateful to the donors of the
Petroleum Research Fund, administered by the American
Chemical Society, for financial support.
1
8.5 Hz, 2COax), 144.64 (d, J(PC) ) 28.5 Hz, CdCH2), 136.85 (d,
3J(PC) ) 1.9 Hz, Ci′), 133.49 (d, J(PC) ) 35.2 Hz, Ci), 133.15 (d,
1
2J(PC) ) 13.1 Hz, Co), 132.48 (s, Co′), 130.20 (d, J(PC) ) 1.9, Hz,
4
Supporting Information Available: An X-ray crystallographic file,
in CIF format, for E-G is available on the Internet only. Access
information is given on any current masthead page.
Cp), 130.02 (s, Cp′), 129.07 (s, Cm′), 128.65 (d, 3J(PC) ) 9.6 Hz, Cm),
2
2
126.43 (d, J(PC) ) 2.1 Hz, CdCH2), 36.71 (d, J(PC) ) 31.8 Hz,
CH2).
IC9711170
N: IR (CH2Cl2): νCO (cm-1) 2020 (w), 2010 (sh), 1911 (s, br), 1882
(sh). 1H NMR (CDCl3, 499.86 MHz): δ 7.3-7.6 (m, 20H, aromatic
H’s), 5.95 (s, 1H, Hb), 5.15 (s, 1H, Ha), 3.05 (s, 2H, CH2). 13C{1H}
(15) International Tables for X-Ray Crystallography; D. Reidel Publishing:
Boston, MA, 1992; Vol. C.