The C=O and C=S bond cleavage in carbon dioxide and tolyl isothiocyanate by reactions with the Mo(0) tetraphosphine complex [Mo{meso-o-C6H 4(PPhCH2CH2PPh2)2} (Ph2PCH2CH2PPh2)]

Article abstract of DOI:10.1016/j.jorganchem.2004.11.020

A Mo(0) complex containing a new tetraphosphine ligand [Mo(P ₄)(dppe)] (1; P₄ = meso-o-C₆H ₄(PPhCH₂CH₂PPh₂)₂, dppe = Ph₂PCH₂CH₂PPh₂) reacted with CO₂ (1 atm) at 60°C in benzene to give a Mo(0) carbonyl complex fac-[Mo(CO)(η³-P₄O)(dppe)] (2), where the O abstraction from CO₂ by one terminal P atom in P₄ takes place to give the dangling P(O)Ph₂ moiety together with the coordinated CO. On the other hand, reaction of 1 with TolNCS (Tol = m-MeC ₆H₄) in benzene at 60°C resulted in the incorporation of three TolNCS molecules to the Mo center, forming a Mo(0) isocyanide- isothiocyanate complex trans,mer-[Mo(TolNC)₂(η²- TolNCS)(η³-P₄S)] (4), where the S abstraction occurs from two TolNCS molecules by P₄ and dppe to give the η³-P₄S ligand and free dppeS, respectively, together with two coordinated TolNC molecules. The remaining site of the Mo center is occupied by the third TolNCS ligating at the CS bond in an η²- manner. The X-ray analysis has been undertaken to determine the detailed structures for 2 and 4.

Full text of DOI:10.1016/j.jorganchem.2004.11.020

Journal of Organometallic Chemistry 690 (2005) 1140–1146
www.elsevier.com/locate/jorganchem
The C@O and C@S bond cleavage in carbon dioxide and
tolyl isothiocyanate by reactions with the Mo(0)
tetraphosphine complex
[Mo{meso-o-C6H4(PPhCH2CH2PPh2)2}(Ph2PCH2CH2PPh2)]
a
Takeshi Ohnishi , Hidetake Seino , Masanobu Hidai , Yasushi Mizobe
a
b
a,
*
a
Institute of Industrial Science, The University of Tokyo, Meguro-ku, Tokyo 153-8505, Japan
b
Department of Materials Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science,
Noda, Chiba 278-8510, Japan
Received 13 October 2004; accepted 11 November 2004
Available online 28 December 2004
Abstract
A Mo(0) complex containing a new tetraphosphine ligand [Mo(P4)(dppe)] (1; P4 = meso-o-C6H4(PPhCH2CH2PPh2)2,
dppe = Ph2PCH2CH2PPh2) reacted with CO2 (1 atm) at 60 °C in benzene to give a Mo(0) carbonyl complex fac-[Mo(CO)(g3-
P4@O)(dppe)] (2), where the O abstraction from CO2 by one terminal P atom in P4 takes place to give the dangling P(@O)Ph2 moi-
ety together with the coordinated CO. On the other hand, reaction of 1 with TolNCS (Tol = m-MeC6H4) in benzene at 60 °C
resulted in the incorporation of three TolNCS molecules to the Mo center, forming a Mo(0) isocyanide–isothiocyanate complex
trans,mer-[Mo(TolNC)2(g2-TolNCS)(g3-P4@S)] (4), where the S abstraction occurs from two TolNCS molecules by P4 and dppe
to give the g3-P4@S ligand and free dppe@S, respectively, together with two coordinated TolNC molecules. The remaining site
of the Mo center is occupied by the third TolNCS ligating at the C@S bond in an g2-manner. The X-ray analysis has been under-
taken to determine the detailed structures for 2 and 4.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Molybdenum complex; Tetraphosphine complex; Carbon dioxide; Isothiocyanate; Phosphine–phosphine oxide ligand; Phosphine–ph-
osphine sulfide ligand
1. Introduction
of benzene. Subsequent study on the reactions of 1 with
small molecules such as nitrile, CO, and isocyanide has
resulted in the isolation of a series of substitution
products including fac-[Mo(L)(g3-P4)(dppe)], cis-
[Mo(L)2(g4-P4)], trans-[Mo(L)2(g2-P4)(dppe)], and fac-
[Mo(L)3(g3-P4)] (L = PhCN, CO, and/or XyNC;
Xy = 2,6-Me2C6H3) [2], whereby the P4 ligand can read-
ily change its coordination mode from g4 to g3 and then
to g2, and in certain cases from g2 to g3 and from g3 to
g4, because of the substantially weaker binding of the
terminal P atoms than the inner P atoms. Now we have
found that in the reactions of 1 with CO2 and TolNCS
(Tol = m-MeC6H4) the C@O and C@S bond cleavage
We reported previously the facile formation of
[Mo(P4)(dppe)] (1; P4 = meso-o-C6H4(PPhCH2CH2-
PPh2)2,
dppe = Ph2PCH2CH2PPh2)
from
trans-
[Mo(N2)2(dppe)2] and dppe [1]. Complex 1 contains a
new tetradentate phosphine P4, which is generated in
the coordination sphere of Mo stereoselectively via the
condensation of two dppe ligands with concomitant loss
*
Corresponding author. Tel.: +81 3 5452 6360; fax: +81 3 5452
6361.
E-mail address: ymizobe@iis.u-tokyo.ac.jp (Y. Mizobe).
0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.11.020

T. Ohnishi et al. / Journal of Organometallic Chemistry 690 (2005) 1140–1146
1141
takes place to give the coordinated CO and isocyanide
accompanied by the transfer of the O and S atoms to
the P atoms in the phosphine ligands. We wish to de-
scribe here the details of these interesting reactions of
1. It is to be noted that although a significant number
of tetraphosphines are known and the preparation of
mono- and multi-nuclear complexes containing these
phosphines as ligands has also been reported [3], studies
on the reactivities of the tetraphosphine complexes are
still quite rare.
drawing is depicted in Fig. 1, while the important bond
distances and angles are listed in Table 1. Reactions of
CS2 with 1 were also carried out in benzene, toluene,
and THF under various conditions. However, no char-
acterizable Mo-containing products were isolated.
As shown in Fig. 1, 2 has an octahedral structure with
the facial P4@O ligand bonded by three P atoms, the
dppe ligand, and CO occupying the position trans to
the terminal P atom in the P4@O ligand. The Mo–P(1)
˚
bond distance trans to the CO ligand at 2.573(2) A is
substantially longer than the other Mo–P bonds in the
˚
range 2.38–2.50 A. The Mo–C(73) and C(73)–O(1) bond
2. Results and discussion
lengths are not exceptional as those of the end-on CO li-
gand bonded to the Mo(0) center. The P@O bond dis-
˚
tance at 1.485(4) A is typical as that of the tertiary
phosphine oxide (e.g. mean value of 72 compounds:
2.1. Reaction of 1 with CO2
˚
1.489 A [4]).
When 1 dissolved in benzene was treated with CO2
gas (1 atm) at 30 °C, reaction took place to give fac-
[Mo(CO)(g3-P4@O)(dppe)] (2) very slowly. Even after
4 days a significant amount of unreacted 1 remained in
the reaction mixture. By analogous treatment at 60 °C,
the reaction completed by 6 h and 2 was isolated as
red crystals in 32% yield by addition of hexane to the
concentrated product solution (Eq. (1)).
Table 1
˚
Selected bond distances (A) and angles (°) in 2 and 4
Compound 2
Bond distance
Mo–P(1)
Mo–P(3)
Mo–P(6)
P(4)–O(2)
2.573(2)
2.460(2)
2.462(2)
1.485(4)
Mo–P(2)
Mo–P(5)
2.389(2)
2.495(2)
1.935(5)
1.178(5)
Mo–C(73)
C(73)–O(1)
Bond angle
P(1)–Mo–P(2)
P(1)–Mo–P(5)
P(1)–Mo–C(73)
P(2)–Mo–P(5)
P(2)–Mo–C(73)
P(3)–Mo–P(6)
P(5)–Mo–P(6)
P(6)–Mo–C(73)
77.21(5)
105.86(5)
169.5(2)
174.25(5)
92.4(2)
P(1)–Mo–P(3)
P(1)–Mo–P(6)
P(2)–Mo–P(3)
P(2)–Mo–P(6)
P(3)–Mo–P(5)
P(3)–Mo–C(73)
P(5)–Mo–C(73)
Mo–C(73)–O(1)
92.85(5)
91.44(5)
80.49(5)
94.85(5)
104.02(5)
84.4(1)
ð1Þ
172.80(5)
80.32(5)
90.4(1)
In this reaction, oxygen abstraction from CO2 by one
terminal P atom in P4 takes place to give the coordi-
nated CO and the dangling P(@O)Ph2 moiety in the
g3-P4@O ligand. The structure of 2 has been determined
unambiguously by the X-ray analysis; the ORTEP
84.6(2)
176.9(4)
Compound 4
Bond distance
Mo–P(1)
2.501(2)
2.452(2)
2.018(5)
2.529(2)
1.178(6)
1.736(5)
Mo–P(2)
2.456(1)
2.105(5)
2.144(5)
1.155(6)
1.256(6)
1.954(2)
Mo–P(3)
Mo–C(55)
Mo–S(2)
Mo–C(47)
Mo–C(63)
C(47)–N(1)
C(63)–N(3)
P(4)–S(1)
C(55)–N(2)
S(2)–C(63)
O(1)
C(73)
Bond angle
P(1)–Mo–P(2)
P(1)–Mo–C(47)
P(1)–Mo–S(2)
P(2)–Mo–P(3)
P(2)–Mo–C(55)
P(2)–Mo–C(63)
P(3)–Mo–C(55)
P(3)–Mo–C(63)
C(47)–Mo–S(2)
C(55)–Mo–S(2)
S(2)–Mo–C(63)
C(47)–N(1)–C(48)
C(55)–N(2)–C(56)
Mo–C(63)–S(2)
S(2)–C(63)–N(3)
76.69(6)
96.1(1)
83.10(6)
74.48(6)
86.0(2)
157.9(1)
86.6(2)
83.5(2)
84.7(1)
88.9(1)
42.6(1)
173.3(6)
157.7(6)
80.6(2)
135.0(4)
P(1)–Mo–P(3)
151.09(5)
89.3(1)
P(5)
P(6)
P(1)–Mo–C(55)
P(1)–Mo–C(63)
P(2)–Mo–C(47)
P(2)–Mo–S(2)
125.4(1)
102.1(1)
159.21(5)
92.0(2)
Mo
P(3)
P(4)
P(2)
P(3)–Mo–C(47)
P(3)–Mo–S(2)
125.36(5)
171.0(2)
76.8(2)
P(1)
C(47)–Mo–C(55)
C(47)–Mo–C(63)
C(55)–Mo–C(63)
Mo–C(47)–N(1)
Mo–C(55)–N(2)
Mo–S(2)–C(63)
Mo–C(63)–N(3)
C(63)–N(3)–C(64)
O(2)
94.3(2)
167.6(5)
178.0(5)
56.8(2)
142.9(4)
122.5(5)
Fig. 1. An ORTEP drawing of 2 drawn at the 30% probability level.
Hydrogen atoms are omitted for clarity.

1142
T. Ohnishi et al. / Journal of Organometallic Chemistry 690 (2005) 1140–1146
The IR spectrum shows two characteristic bands at
complex [Cp*Mo(PMe3)3H] (Cp* = g5-C5Me5) with
CO2 to give [Cp*Mo(PMe3)2(CO)H] and Me3P@O
[10]. The proposed mechanism involves the initial dis-
1804 and 1186 cmꢀ1, which are assignable to m(C„O)
and m(P@O), respectively. The m(C„O) value of 2 is in
good agreement with those observed for the P4 analogue
fac-[Mo(CO)(g3-P4)(dppe)] (3; 1809 cmꢀ1) [2] and re-
lated Mo(0) complexes fac-[Mo(CO){PhP(CH2CH2-
PPh2)2}(PMe2Ph)2] (1768 cmꢀ1) [5], while the m(P@O)
value corresponds well to those of Ph3P@O and
Me3P@O at 1190 and 1176 cmꢀ1 [6].
placement of PMe3 by CO , yielding [Cp Mo(P-
2
*
O atom
Me3)2(g2-CO2)H], which undergoes the
abstraction by the free PMe3. Formation of 2 from 1
might proceed in an analogous manner, viz., an g2-
CO2 complex [Mo(g2-CO2)(g3-P4)(dppe)] generated ini-
tially is susceptible to the O atom abstraction by the
dangling P atom of the g3-P4 ligand to give 2. By con-
trast, in the reaction of the W(II) complex
[WCl2(PPh2Me)4] with CO2 the C@O bond cleavage
takes place to give instead the W(IV) complex as the
oxidative addition product cis,trans-[WCl2(@O)(CO)-
(PPh2Me)2] [11]. Conversion of the polydentate phos-
phine into the mixed phosphine–phosphine oxide ligand
[12] by the O atom abstraction from CO2 is still quite
rare but is precedent, i.e., treatment of a Ni(0) complex
[Ni(g2-CS2)(triphos)] (triphos = MeC(CH2PPh2)3) with
CO2 at room temperature gave a Ni(II) complex
[Ni(g2-CO3)(g2-triphos@O)] with concurrent liberation
of CO [13]. In this reaction, not only the P atom in tri-
phos but also CO2 acts as the O atom acceptors.
The 31P NMR spectrum of 2 is consistent with its X-
ray structure, indicating that the solid state structure is
preserved also in solution. Thus, the chemical shifts
and coupling constants show clearly that the site trans
to the terminal P atom of P4@O is occupied by CO
and those trans to the inner P atoms of P4@O are by
the dppe P atoms (see Section 3).
It is noteworthy that the P4 analogue 3 obtained di-
rectly from the reaction of 1 with CO gas has a slightly
different geometry around Mo, in which the CO ligand
occupies the position trans to the inner P atom adjacent
to the dangling P atom in the P4 ligand (Chart 1) [2].
The structure of 3 was characterized by its 31P NMR
spectrum, which is apparently different from that of 2
and indicates that the P atom is absent at the site trans
to the inner P atom next to the dangling PPh2 moiety of
the g3-P4 ligand. This structure proposed for 3 is con-
firmed by comparing its 31P NMR data with those of
the crystallographically analyzed 2,6-Me2C6H3NC
2.2. Reaction of 1 with TolNCS
Treatment of 1 with 3 or more equiv of TolNCS in
benzene at 60 °C afforded the bis(isocyanide)–isothiocy-
anate complex trans,mer-[Mo(TolNC)2(g2-TolNCS)(g3-
P4@S)] (4), which was isolated as red crystalline solid in
36 % yield (Eq. (2)).
(XyNC)
analogue
fac-[Mo(XyNC)(g3-P4)(dppe)].
Apparently the geometry around Mo is dependent on
the subtle factors in these complexes [Mo(L)(g3-
P4)(dppe)] and 2.
Extensive studies have been done about the reactions
of CO2 with transition metal complexes [7]. As for those
with the related Mo(0) phosphine complexes, coordina-
tion of CO2 or the disproportionation of CO2 into CO
and CO3 ligands have been reported. Thus, formation
of the substitution products [Mo(CO2)2(dppe)2] was
claimed for trans-[Mo(N2)2(dppe)2] [8], whereas not only
cis-[Mo(g2-CO2)2(PMe3)4] but also the Mo(II) com-
plexes as the disproportionation products [Mo(CO)-
(CO3)(PMe3)4] and [{Mo(CO)(l-CO3)(PMe3)3}2] were
obtained from cis-[Mo(N2)2(PMe3)4] [9].
ð2Þ
It is quite noteworthy that as many as three TolNCS
molecules react with 1, two of which are converted into
TolNC by desulfurization and the remaining TolNCS
binds to the Mo center in an g2 manner at the C@S
bond. With respect to the S abstraction from TolNCS,
one abstracted S atom moves to the terminal P atom
in P4 to give a dangling P(@S)Ph2 moiety and the other
is trapped by dppe. Formation of free dppe@S was con-
firmed by the 31P NMR spectrum of the reaction mix-
ture, exhibiting two doublets at 43.1 and ꢀ13.8 ppm
(J(P–P) = 50 Hz) assignable to dppe = S [14]. Reactions
of 1 with other organic heterocumulenes such as
PhNCO and Ph2CCO did not proceed cleanly and gave
no characterizable products. For 4, single crystals whose
As the reaction quite analogous to the present work,
conversion of CO2 into the coordinated CO and phos-
phine oxide was observed in the reaction of the Mo(II)
Chart 1.

T. Ohnishi et al. / Journal of Organometallic Chemistry 690 (2005) 1140–1146
1143
asymmetric unit contains 4 and two benzene molecules
were obtained in a small amount and the structure was
determined in detail by the X-ray analysis. An ORTEP
drawing is depicted in Fig. 2, while selected bond dis-
tances and angles are listed in Table 1.
Chart 2.
Complex 4 has an octahedral structure with three
meridional P atoms of P4@S and TolNCS ligating in
an g2 manner at the C@S bond in a basal plane together
with two mutually trans TolNC ligands at the apical
positions. For the Mo–P bond lengths, the distance of
N(2) is essentially linear (178.0(5)°), whereas in the other
isocyanide ligand in the opposite side of the basal plane
the C(47)–N(1)–C(48) angle is almost linear (173.3(6)°)
and the Mo–C(47)–N(1) array (167.6(5)°) is bent
slightly. Since the bending of the C–N–C angle in the
end-on isocyanide ligands is accounted for by the contri-
bution of the extreme structure ii to i shown in Chart 2,
this finding can be interpreted in terms of the presence of
greater contribution of the structure ii in the former
TolNC. This correlates well with the other observation
on the bond lengths in these two coordinated TolNC
˚
the terminal P(1) atom from Mo at 2.501(2) A is longer
than those of the inner P(2) and P(3) atoms from Mo at
˚
2.456(1) and 2.452(2) A, respectively. The TolNCS li-
gand coordinates to Mo in a manner that the NCS plane
becomes coplanar with the basal plane. The N(3)–
C(63)–S(2) linkage is bent with the angle of 135.0(4)°
˚
and the C(63)–S(2) bond length at 1.736(5) A is signifi-
˚
cantly elongated from the typical C@S double bond
length of ca. 1.66–1.68 A [4]. The X-ray structure deter-
molecules, viz. the Mo–C(55) distance at 2.018(5) A in
the former is shorter than the Mo–C(47) distance at
˚
mination of the g2-RNCS ligands has previously been
carried out for [Co(g2-PhNCS){N(CH2CH2PPh2)3}](5)
and [Ni(g2-PhNCS)(triphos)] (6), in which the N–C–S
angle and the C–S bond length are 141.1(1)° and
2.105(5) A in the latter and the C(55)–N(2) bond of
1.178(6) A is elongated from the C(47)–N(1) bond of
˚
˚
˚
1.155(6) A, respectively.
In general, bent C–N–C linkage is found in the ali-
phatic isocyanides bound to a zero-valent metal center
having no p-accepting ligands, in which electron density
remains localized on the N atom and the C–N–C linkage
tends to be bent due to the pairing effects of the electrons
[16]. In the aryl isocyanide ligands, due to the ability to
delocalize the charge from the N atom into the aromatic
rings significant C–N–C bending is relatively rare
except for, e.g. cis-[(CNC6H4NC)2W(dppe)2] (137(1)°,
141.4(8)°) [16], trans-[Mo(PhNC)(p-MeOC6H4CN)-
(dppe)2] (149.8(4)°), trans-[Mo(p-Me2NC6H4NC)(g2-
H2)(dppe)2] (148.4(4)°) [17], [V(XyNC)6]nꢀ (n = 0: av.
163(4)°, n = 1: av. 158(10)°) [18], and cis-[Mo(X-
yNC)2(P4)] (155.8(3) and 169.3(3)°) [2]. In 4, it is likely
that bending of the C–N–C angles is greatly affected
not only by electronic effects but also by steric effects
as well as crystal packing forces [18].
˚
˚
1.72(2) A for the former, and 141.8(2)° and 1.68(2) A
for the latter [15].
Two mutually trans TolNC ligands are not equivalent
because of the presence of chiral P(2) and P(3) atoms. It
is interesting to note that the structures of two TolNC
ligands differ slightly. Thus, in the isocyanide ligating
from the direction to which the o-phenylene group
points, the C(55)–N(2)–C(56) linkage is bent consider-
ably with the angle of 157.7(6)° and the Mo–C(55)–
C(56)
Formation of the phosphine sulfide moiety in the g3-
P4@S ligand has also been unambiguously demon-
strated by the X-ray analysis, where the P@S bond
S(1)
N(2)
P(2)
P(4)
C(55)
˚
P(3)
length at 1.954(2) A is in good agreement with the re-
˚
P(1)
Mo
ported P@S bond distance of 1.954 A as the mean value
of 13 tertiary phosphine sulfides [4].
C(63)
1
The H NMR spectrum of 4 shows three singlets at
S(2)
N(3)
2.28, 1.86, and 1.77 ppm due to the Me protons of three
inequivalent Tol groups, which is consistent with the re-
sults of the X-ray analysis, although these three signals
were unable to be assigned. In the IR spectrum (KBr),
the m(N„C) bands of two TolNC ligands are recorded
as only one intense absorption at 1897 cmꢀ1, while the
characteristic m(N@C) band due to the g2-TolNCS li-
gand appears at 1598 cmꢀ1. The m(N„C) value
observed for 4 is not exceptional as that of the end-on
aryl isocyanides. For comparison, the m(N@C)
C(47)
C(64)
N(1)
C(48)
Fig. 2. An ORTEP drawing of 4 drawn at the 30% probability level.
Hydrogen atoms are omitted for clarity.

1144
T. Ohnishi et al. / Journal of Organometallic Chemistry 690 (2005) 1140–1146
values observed for the g2-SCNPh complexes 5 [19] and
6 [20] cited above are 1620 and 1640 cmꢀ1, respectively.
As described above, the reaction with CO2 is pre-
sumed to be initiated by the formation of [Mo(g2-
CO2)(g3-P4)(dppe)] from {Mo(g3-P4)(dppe)} and CO2.
In contrast, since sterically much bulkier TolNCS can-
not bind directly the vacant site of {Mo( g3-P4)(dppe)},
dissociation of another P atom might be required prior
to the coordination of TolNCS. The species containing
both g3-P4 and g1-dppe ligands thus obtained
{Mo(g2-TolNCS)(g3-P4)(g1-dppe)} is likely to undergo
the S abstraction by the dangling P atom in the g1-dppe
ligand to give {Mo(TolNC)(g4-P4)} and free dppe@S.
This mechanism is supported by the finding that the
reaction of 1 with 2 equiv of TolNCS gives [Mo-
(TolNC)(g2-TolNCS)(g4-P4)] and dppe@S, although
this complex could not be isolated in an analytically
pure form and was characterized only spectroscopically.
Conversion of RNCS into RNC has been observed in
the reaction of [CpCo(PMe3)2] (Cp@g5-C5H5) with
RNCS (R = Me, Ph) to give [CpCo(PMe3)(RNC)] and
Me3P@S [21] and that of the g2-SCNPh complex 5 with
NaBPh4 to afford [Co(PhNC){N(CH2CH2PPh2)3}-
[BPh4] [19]. For the latter reaction, the fate of the ab-
stracted sulfur is not addressed.
Chart 4.
3.2. fac-[Mo(CO)(g3-P4@O)(dppe)] (2)
Carbon dioxide gas was bubbled through a benzene
suspension (8 mL) of 1 (136 mg, 0.106 mmol) for 5
min and the mixture was continuously stirred under a
CO2 atmosphere at 60 °C for 6 h. After cooling, hexane
was added under N2 to the concentrated product solu-
tion, giving 2 as red crystals (41 mg, 31% yield).
31P{1H} NMR (C6D6, ppm): 95.7 (P2), 69.2 (P3), 67.5
(P6), 65.8 (P5), 47.7 (P1), 27.7 (P4); J(P2–P6) = 92,
J(P3–P5) = 85, J(P3–P4) = 23 Hz. IR (KBr, cmꢀ1):
1804 (C„O), 1186 (P@O). Anal. Calc. for C73H66O2P6-
Mo: C, 69.75; H, 5.29. Found: C, 70.15; H, 5.47%.
3.3. trans,mer-[Mo(TolNC)2(g2-TolNCS)(g3-P4@S)]
(4)
3. Experimental
3.1. General considerations
To a solution of 1 (127 mg, 0.0984 mmol) in ben-
zene (10 mL) was added TolNCS (45 mg, 0.301 mmol),
and a mixture was stirred at 60 °C for 18 h. After fil-
tration, hexane was added to the concentrated filtrate
to give 4 Æ C6H6 as red microcrystalline powder (46
mg, 36% yield). Single crystals obtained in a small
amount were characterized to be 4 Æ 2C6H6 by the X-
ray crystallography. 4 Æ C6H6: 31P{1H} NMR (C6D6,
ppm): 84.8 (P2), 73.0 (P3), 70.2 (P1), 45.9 (P4); J(P1–
P3) = 75, J(P3–P4) = 30, J(P1–P2) = 23, J(P2–P3) = 23
All manipulations were carried out under N2 using
standard Schlenk techniques. Solvents were dried by
common methods and distilled under N2 before use.
Complex 1 was prepared as described previously [1],
while CO2 gas and all reagents were commercially ob-
tained and used without further purification.
NMR and IR spectra were measured at room temper-
ature on a JEOL alpha-400 or a JASCO FT/IR-420
spectrometer. For 31P NMR data, numbering of the P
atoms in 2 and 4 are shown in Charts 3 and 4, respec-
tively. Elemental analyses were done with a Perkin–
Elmer 2400 series II CHN analyzer.
1
Hz. H NMR (C6D6, ppm): 2.28, 1.86, 1.77 (3H each,
s, Me in TolNC and TolNCS). IR (KBr, cmꢀ1): 1897
(N„C),
1598
(N@C).
Anal.
Calc.
for
C76H69N3S2P4Mo: C, 69.77; H, 5.32; N, 3.21. Found:
C, 69.70; H, 5.65; N, 2.96%.
3.4. Mo(TolNC)(g2-TolNCS)(g4-P4)]
A solution containing 1 (127 mg, 0.984 mmol) and 2
equiv of TolNCS (30 mg) in benzene (10 mL) was stirred
at 60 °C for 18 h. After filtration, the filtrate was dried
up and the residue was crystallized from benzene–hex-
ane, yielding the title compound as a red-brown solid.
The yield was not determined since the product was
not available in an analytically pure form. 31P{1H}
1
Chart 3.
NMR (C6D6, ppm): 97, 91, 74, 49. H NMR (C6D6,

T. Ohnishi et al. / Journal of Organometallic Chemistry 690 (2005) 1140–1146
1145
ppm): 2.15, 1.92 (3H each, s, Me in TolNC and Tol-
4. Supplementary material
NCS). IR (KBr, cmꢀ1): 1930 (N„C), 1587 (N@C).
The 31P chemical shifts are typical to the g4-P4 ligand
with the fac-mer array [1,2], although the coupling con-
stants were unable to be determined due to the broaden-
ing of the signals.
Listing of atomic coordinates, anisotropic thermal
parameters, and extensive interatomic distances and an-
gles for 2 and 4 have been deposited with the Cambridge
Crystallographic Data Centre, CCDC Nos. 257393 and
257394, respectively. Copies of this information may be
obtained free of charge from The Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (fax: +44-
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or http://
www.ccdc.cam.ac.uk).
3.5. X-ray crystallography
Single crystals were sealed in glass capillaries under
argon and mounted on a Rigaku Mercury-CCD
diffractometer for 2 or a Rigaku AFC7R four-circled
diffractometer for 4 equipped with a graphite-mono-
chromatized Mo Ka source. All diffraction studies were
performed at 23 °C and intensity data were corrected for
Lorents-polarization effects and for absorption. Details
are shown in Table 2.
Structure solution and refinements were carried out
using the CrystalStructure program package [22]. The
positions of non-hydrogen atoms were determined by
Patterson methods (PATTY) [23] and subsequent Fou-
rier synthesis (DIRDIF 99) [24]. These were refined
with anisotropic thermal parameters, while hydrogen
atoms were placed at the calculated positions and in-
cluded at the final stages of refinements with fixed
parameters.
Acknowledgments
This work was supported by Grant-in-Aid for Scien-
tific Research on Priority Areas (No. 14078206, ‘‘Reac-
tion Control of Dynamic Complexes’’) from the
Ministry of Education, Culture, Sports, Science and
Technology, Japan and by CREST of JST (Japan Sci-
ence and Technology Agency).
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14675 (0.049)
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P
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1146
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CRYSTALS Issue 10, CrystalStructure 3.00: Crystal Structure