Reactivity of cyclo-(PhX)6 (X = As, P) towards [M3L2(CO)10] (M = Ru, L = CO or NCMe; M = Fe, L = CO)

Article abstract of DOI:10.1016/S0022-328X(02)01892-2

Reaction of [Ru₃(CO)₁₀(NCMe)₂] with cyclo-(PhX)₆ (X = As 1a, P 1b) in toluene at ambient temperature gives [Ru₃{μ-cyclo-(PhX)₆}(CO)₁₀] (X = As 2a, P 2b), in which the intact six-membered rings adopt chair conformations and bridge metal-metal edges via either two arsine (2a) or two phosphorus (2b) atoms in the 1,5 positions of the respective rings. Conversely, treatment of [Ru₃(CO)₁₂] with cyclo-(PhX)₆ (X = As 1a, P 1b) in toluene at elevated temperature results in fragmentation of the six-membered rings to afford [Ru4(μ₃-AsPh)₂(CO)₁₃] (3) and with [Fe₃(CO)₁₂] in toluene at elevated temperature to furnish [Fe₃(μ₃-AsPh)₂(CO) ₉] (5) as the sole product. However, treatment of 1b with [Fe₃(CO)₁₂] gives [Fe₃(μ ₃-PPh₂)₂(CO)₉] (6), the phosphorus analogue of 5, along with [Fe₂{μ-η2-catena -(P₄Ph₄)}(CO)₆] (7) and [Fe₂{μ₄-(P₂Ph₂)} (CO)₆]₂ (8). In addition, the mixed phosphinidene-arsenidene complex [Fe₃(m₃-PPh) (μ₃-AsPh)(CO)₉] (9) can be obtained on treatment of 1 with a 1:1 mixture of 1a and 1b. Single crystal X-ray diffraction studies have been performed on 2a, 3,4.2CH₂Cl₂, and 8.

Full text of DOI:10.1016/S0022-328X(02)01892-2

Journal of Organometallic Chemistry 664 (2002) 27Á36
/
www.elsevier.com/locate/jorganchem
Reactivity of cyclo-(PhX)6 (Xꢀ
/
As, P) towards [M3L2(CO)10]
(MꢀRu, LꢀCO or NCMe; Mꢀ
/
/
/
Fe, LꢀCO)
/
Rohini M. De Silva a, Martin J. Mays a,ꢁ, Gregory A. Solan b,ꢁ
a Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK
b Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK
Received 11 August 2002; accepted 3 September 2002
Abstract
Reaction of [Ru3(CO)10(NCMe)2] with cyclo-(PhX)6 (Xꢀ
(PhX)6}(CO)10] (XꢀAs 2a, P 2b), in which the intact six-membered rings adopt chair conformations and bridge metalÁ
via either two arsine (2a) or two phosphorus (2b) atoms in the 1,5 positions of the respective rings. Conversely, treatment of
[Ru3(CO)12] with cyclo-(PhX)6 (XꢀAs 1a, P 1b) in toluene at elevated temperature results in fragmentation of the six-membered
/
As 1a, P 1b) in toluene at ambient temperature gives [Ru3{m-cyclo-
/
/metal edges
/
rings to afford [Ru4(m3-AsPh)2(CO)13] (3) and [Ru6(m4-PPh)3(m3-PPh)2(CO)12] (4), respectively. Fragmentation of the cyclo-
hexaarsane ring in 1a also occurs on reaction with [Fe3(CO)12] in toluene at elevated temperature to furnish [Fe3(m3-AsPh)2(CO)9] (5)
as the sole product. However, treatment of 1b with [Fe3(CO)12] gives [Fe3(m3-PPh2)2(CO)9] (6), the phosphorus analogue of 5, along
with [Fe2{m-h2-catena-(P4Ph4)}(CO)6] (7) and [Fe2{m4-(P2Ph2)}(CO)6]2 (8). In addition, the mixed phosphinideneÁ
/
arsenidene
complex [Fe3(m3-PPh)(m3-AsPh)(CO)9] (9) can be obtained on treatment of 1 with a 1:1 mixture of 1a and 1b. Single crystal X-ray
2CH2Cl2, and 8.
diffraction studies have been performed on 2a, 3, 4×
/
# 2002 Published by Elsevier Science B.V.
Keywords: Cluster; Ruthenium; Iron; Arsenic; Phosphorus
1. Introduction
As part of a programme investigating the chemistry of
aryl-substituted hexameric members of the CPA and
CPP families, we carried out an examination of their
reactions with Group 9 transition metal carbonyl and
mixed-metal Groups 8/9 carbonyl complexes under
relatively mild conditions [4]. For example, cleavage
The application of cyclo-polyarsanes (CPAs) [(RAs)n,
Rꢀ
(CPPs) [(RP)n, nꢀ
of transition metal cluster complexes has been the
subject of intense research activity [1Á3]. This can be
/
hydrocarbyl, nꢀ
/
4Á6] and cyclo-polyphosphanes
/
/
3Á6] as reagents for the preparation
/
and fragmentation of the cyclo-(PhX)6 (Xꢀ
ring is promoted by the room temperature addition of
[Co2(CO)8] [5Á7], while the alkyne-bridged dicobalt
complex [Co2(m-CRCR)(CO)6] and the thioxo-capped
dicobaltÁiron complex [Co2Fe(m3-S)(CO)9] support the
/
As 1a, P 1b)
/
attributed, in part, to the diversity of structural types
that are accessible, often containing unparalled hybrid
transition metal-main group architectures, in which the
CPA or the CPP has ring-opened and fragmented to
generate capping groups and chains (or combinations of
both) based on RAs/RP units or unsubstituted Group
15 atoms.
/
/
coordination of intact rings under similar conditions [8].
In the case of [Co2Fe(m3-S){m-cyclo-(PhP)6}(CO)7],
thermolysis leads to fragmentation of the coordinated
cyclo-(PhP)6 (1a) ring to give [Co2Fe(m3-SPPh)(m-
h2:h2:h1-P5Ph5)(CO)5] as the sole reaction product.
Herein we are concerned with a study of the reactivity
of 1a and 1b towards the homotrimetallic Group 8
transition metal carbonyl complexes [Ru3(CO)10-
(NCMe)2], [Ru3(CO)12] and [Fe3(CO)12].
ꢁ Corresponding authors. Fax: ꢂ44-1223-336362
/
E-mail addresses: mjm14@cam.ac.uk (M.J. Mays), gas8@le.ac.uk
(G.A. Solan).
0022-328X/02/$ - see front matter # 2002 Published by Elsevier Science B.V.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 8 9 2 - 2

28
R.M. De Silva et al. / Journal of Organometallic Chemistry 664 (2002) 27Á36
/
2. Results and discussion
bond is longer than the unbridged RuÃ
/
Ru bonds
˚
[2.888(1) A as compared to 2.844(1) and 2.866(1) A].
˚
This elongation has also been observed with a number
2.1. Reaction of [Ru3(CO)10L2] (Lꢀ
/
NCMe, CO) with
of triruthenium complexes in which a metalÁ
/
metal edge
is bridged by a diarsine ligand [10]. The ruthenium to
cyclo-(PhX)6 (XꢀAs 1a, P 1b)
/
˚
arsenic average bond length of 2.485 A for 2a agree
closely with the RuÃAs distances in related species
[10,11].
The reaction of [Ru3(CO)10(NCMe)2] with an equi-
molar amount of cyclo-(PhX)6 (XꢀAs 1a, P 1b) in
toluene at ambient temperature affords [Ru3{m-cyclo-
(PhX)6}(CO)10] (XꢀAs 2a, P 2b) in high yield (Scheme
/
/
/
The spectroscopic properties of 2a are in accord with
the solid state structure being maintained in solution.
The IR spectrum of 2a exhibits three strong bands
together with several weak bands in the terminal
carbonyl region. The pattern of bands is very similar
to those observed for other bis-equatorially substituted
1
1). Both complexes have been characterised by IR, H-,
31P- (for 2b), 13C-NMR spectroscopy, mass spectro-
metry and by elemental analysis (see Table 1). In
addition, the molecular structure for 2a has been
determined by single crystal X-ray diffraction. The
molecular structure of 2a is shown in Fig. 1 while
selected bond distances and angles are listed in Table 2.
Crystals suitable for the analysis were grown by slow
diffusion of hexane into a dichloromethane solution of
2a at 0 8C. The structure of 2a consists of a triangular
Ru3 core in which one edge is bridged by the two arsenic
atoms in the 1,5 positions of the intact cyclo-hexaarsane
triruthenium and triosmium clusters [3aÁ3d]. On the
/
basis of the close similarity of the IR data, complex 2b is
assigned a similar structure with phosphorus atoms in
place of arsenic atoms. The FAB mass spectra for 2a
and 2b both show molecular ion peaks and fragmenta-
tion peaks corresponding to the loss of up to 10
carbonyl groups. The one dimensional 31P{1H}-NMR
spectrum of 2b shows four multiplets at d 39.2, 2.2,
ring. The average AsÃ
arsenic ring is close to that in cyclo-(PhAs)6 (91.08) [9].
As(2) angle of 89.3(1)8, is within the
/
AsÃ
/
As angle of 93.58 in the
ꢃ
/
5.8, ꢃ37.8, with an integral ratio of 1:2:2:1, respec-
/
The As(1)Ã
/
As(3)Ã
/
tively and consistent with 2b possessing an approximate
mirror plane of symmetry passing through the midpoint
range of the values for the free ligand although
noticeably larger than the corresponding angles in
of the bridged RuÃ
/
Ru bond, P2 and P5 (see Scheme 1).
[Co2(m-RCCR){m-cyclo-(PhAs)6}(CO)4] (Rꢀ
and [Co2Fe(m3-S){m-cyclo-(PhAs)6}(CO)7] [8]. This can
be attributed to the difference in the metalÃmetal
distances of these complexes. The bridged RuÃRu
/H, Ph) [5]
On the basis of a two-dimensional COSY-90 31P-NMR
spectroscopy, the four signals have been ascribed to P2
/
(d 39.2), P1/P3 (d 2.2), P4/P6 (d ꢃ
/
5.8) and P5 (d ꢃ
37.8).
/
/
Scheme 1. Reagents and conditions: (i) [Ru3(CO)10(NCMe)2], (1a or 1b), room temperature; (ii) [Ru3(CO)12], (1a), toluene, heat; (iii) [Ru3(CO)12],
(1b), heptane, heat; (iv) [Fe3(CO)12], toluene, heat, (1a); (v) [Fe3(CO)12], (1b), toluene, heat; (vi) [Fe3(CO)12], (1a and 1b), toluene, heat.

Table 1
Spectroscopic and analytical data for the new complexes 2a, 2b, 3, 5, 8 and 9
a
c
d
Compound n(CO) (cmꢃ1
)
1H-NMR
13C-NMR (d)
31P-NMR (d)
FAB mass spec-
trum
Microanalysis
e
(%)
b
(d)
C
H
2a
2b
3
2086s, 2058w,
2028m, 2011vs,
1959m
8.1Á
30H, Ph]
/
6.4 [m,
211.0 [s, CO], 137Á
/
128 [m, Ph]
1495 ([MꢂꢃnCO], 36.94
nꢀ1Á10) (36.89)
2.06
(2.02)
/
2084s, 2025m,
2012vs, 1982m,
1958m
8.2Á
/
6.7 [m,
217.0 [m, CO], 137Á
/
127 [m, Ph]
39.2 [m, P(2)], 2.2 [m, P(1),
P(3)], ꢃ5.8 [m, P(4), P(6)],
ꢃ37.8 [m, P(5)]
1231 ([MꢂꢃnCO], 44.50
nꢀ1Á10) (44.85)
2.47
(2.45)
30H, Ph]
/
2104m, 2070s,
2052vs, 2036s,
1995m
7.8Á
/
7.1 [m,
203.0 [s, 1CO], 199.6 [s, 1CO], 199.3 [br, 3CO], 198.0 [s, 1CO], 196.0 [s,
1CO], 194.0 [s, 3CO], 192.0 [s, 1CO], 191.0 [s, 1CO], 185.0 [s, 1CO], 147.0
1072 ([MꢂꢃnCO], 28.08
nꢀ1Á11) (28.00)
0.95
(0.93)
10H, Ph]
/
[AsC(Ph)], 144.0 [s, AsC(Ph)], 132Á
214.0 [s, CO], 207.0 [br, CO], 136Á129 [m, Ph]
/128 [m, Ph]
5
2038vs, 2015s,
1996s
7.6 [m, 5H,
Ph], 7.5 [m,
5H, Ph]
/
724 ([MꢂꢃnCO], 35.56
nꢀ1Á9) (34.85)
1.60
(1.39)
/
8
9
2046vs, 2023s,
1998s, 1968m
7.4Á
20H, Ph]
/
6.9 [m,
213.0 [m, CO], 209.0 [m, CO], 208.0 [m, CO], 207.0 [m, CO], 135Á
Ph]
/
127 [m, 536.0 [t, 2J(PP) 174, 2P,
991 ([MꢂꢃnCO], 43.37
12) (43.59)
2.07
(2.03)
(PPh)2], 233.0 [t, 2P, (PPh)2] nꢀ1Á
/
2038vs, 2015s,
1997m
7.5Á7.5 [m,
/
214.0 [m, CO], 213.6 [s, CO], 213.2 [s, CO], 212.3 [s, br, CO], 207.8 [br, 339.0 [s, 1P, (PPh)]
CO], 138Á128 [m, Ph]
680 ([MꢂꢃnCO],
nꢀ1Á9)
Á/
Á/
Ph]
/
/
a
b
c
Recorded in dichloromethane solution.
1H-NMR chemical shifts (d) in ppm relative to SiMe4 (0.0 ppm), coupling constants in Hz in CDCl3 at 293 K.
Chemical shifts in ppm relative to SiMe4 (0.0), in CDCl3 at 293 K.
31P-NMR chemical shifts (d) in ppm relative to external 85% H3PO4 (0.0 ppm), {1H}-gated decoupled, measured in CDCl3 at 293 K.
Calculated values in parentheses.
d
e

30
R.M. De Silva et al. / Journal of Organometallic Chemistry 664 (2002) 27Á36
/
Fig. 1. Molecular structure of [Ru3{m-cyclo-(PhAs)6}(CO)10] (2a) including the atom numbering scheme. All hydrogen atoms have been omitted for
clarity.
Table 2
˚
Selected bond distances (A) and angles (8) for 2a
Bond distances
Ru(1)ÃRu(2)
Ru(2)ÃRu(3)
Ru(1)ÃRu(3)
Ru(1)ÃAs(2)
Ru(2)ÃAs(1)
As(1)ÃAs(3)
2.888(1) As(1)ÃAs(6)
2.866(1) As(2)ÃAs(3)
2.844(1) As(2)ÃAs(4)
2.474(1) As(4)ÃAs(5)
2.496(1) As(5)ÃAs(6)
2.477(2) Mean RuÃC(carbonyl)
2.487(2)
2.484(2)
2.456(2)
2.475(2)
2.487(2)
1.90
Bond angles
Ru(1)ÃRu(2)ÃRu(3) 59.2(1)
Ru(1)ÃRu(3)ÃRu(2) 60.8(1)
Ru(2)ÃRu(1)ÃRu(3) 60.0(1)
As(2)ÃAs(4)ÃAs(5)
As(3)ÃAs(2)ÃAs(4)
As(3)ÃAs(1)ÃAs(6)
As(4)ÃAs(5)ÃAs(6)
100.3(1)
89.2(1)
90.4(1)
100.3(1)
As(1)ÃAs(3)ÃAs(2)
As(1)ÃAs(6)ÃAs(5)
89.3(1)
95.8(1)
While conservation of the six-membered rings occurs
on reaction of [Ru3(CO)10(MeCN)2] with 1a and 1b,
fragmentation occurs when 1a and 1b are treated with
one equivalent of [Ru3(CO)12] at elevated temperatures.
In the case of 1a this leads to [Ru4(m3-AsPh)2(CO)13] (3)
and for 1b to [Ru6(m4-PPh)3(m3-PPh)2(CO)12] (4). Both 3
1
and 4 have been characterised by IR, H-, 31P- (for 4),
Fig. 2. Molecular structure of [Ru4(m3-AsPh)2(CO)13] (3) including the
atom numbering scheme. All hydrogen atoms have been omitted for
clarity.
13C-NMR spectroscopy, mass spectrometry and by
elemental analysis (see Table 1). In addition the
molecular structures for 3 and 4 have been determined
by single crystal X-ray diffraction. The molecular
structure of 3 is shown in Fig. 2 while selected bond
distances and angles are listed in Table 3. Crystals
suitable for the analysis were grown by slow diffusion of

R.M. De Silva et al. / Journal of Organometallic Chemistry 664 (2002) 27Á
/36
31
Table 3
details were reported [14]. The spectroscopic properties
of 3 are in accord with the solid state structure being
maintained in solution. The IR spectrum of 3 shows five
bands in the n(CO) region which are similar to the
structurally related tetraosmium complex [Os4(m3-
PCF3)2(CO)13] [3d]. The 13C{1H}-NMR spectrum at
room temperature shows seven sharp and two broad
signals in the carbonyl region corresponding to the 13
carbonyl groups. This suggests that six carbonyl groups
on two ruthenium atoms are fluxional at room tem-
perature. By inspection of the crystal structure it was
revealed that the rotation of the three carbonyl groups
residing on Ru(3) is hindered by the four carbonyl
groups on Ru(4). Therefore, the two broad signals can
most likely be attributed to the rapid trigonal rotation of
the three carbonyl ligands on each of the Ru(1) and
Ru(2) atoms.
˚
Selected bond distances (A) and angles (8) for 3
Bond distances
Ru(1)ÃRu(2)
Ru(1)ÃRu(3)
Ru(3)ÃRu(4)
Ru(1)ÃAs(1)
Ru(1)ÃAs(2)
2.930(1) Ru(2)ÃAs(1)
2.970(1) Ru(2)ÃAs(2)
2.921(1) Ru(3)ÃAs(2)
2.456(1) Ru(4)ÃAs(1)
2.499(1) Mean RuÃC(carbonyl)
2.461(1)
2.434(1)
2.448(1)
2.496(1)
1.91
Bond angles
Ru(1)ÃAs(1)ÃRu(2)
Ru(1)ÃAs(1)ÃRu(4) 114.9(1) Ru(2)ÃAs(2)ÃRu(3)
Ru(2)ÃAs(1)ÃRu(4) 124.2(1) As(1)ÃRu(1)ÃAs(2)
73.2(1) Ru(1)ÃAs(2)ÃRu(3)
73.8(1)
124.2(1)
77.8(1)
78.9(1)
Ru(1)ÃAs(2)ÃRu(2)
72.9(1) As(1)ÃRu(2)ÃAs(2)
hexane into a dichloromethane solution of 3 at room
temperature. The molecule consists of an open chain of
four ruthenium atoms with two triply-bridging AsPh
groups. The atom As(1) bridges Ru(4), Ru(1) and Ru(2)
while As(2) bridges Ru(3), Ru(1) and Ru(2). Therefore,
The molecular structure of 4×
/
2CH2Cl2 is shown in
Fig. 3 while selected bond distances and angles are listed
in Table 4. Crystals suitable for the analysis were grown
by diffusion of hexane into a dichloromethane solution
of 4 at 0 8C. A different crystallographic modification
of 4, in which no solvate is present, has been reported
the Ru(1)Ã
/
Ru(2) bond is bridged by both the pheny-
larsenidine groups forming a Ru2As2 butterfly unit.
Each ruthenium atom is coordinated by three terminal
carbonyl groups except Ru(4) which has four terminal
carbonyl groups. All the ruthenium atoms have approxi-
mately octahedral geometry except Ru(1) which is
previously [15]. The structure of 4×
/
2CH2Cl2 is essentially
the same as the non-solvated form with the six
ruthenium atoms [Ru(1), Ru(2), Ru(3), Ru(1A),
Ru(2A), Ru(3A)], adopting a distorted trigonal pris-
matic geometry with all the triangular and square faces
capped by phenylphosphinidene ligands and each ruthe-
nium atom bound by two carbonyl ligands. The
seven-coordinate. The average RuÃ
/
Ru bond length of
˚
˚
2.94 A, is longer than in [Ru3(CO)12] (2.853 A) [12] but
within the normal range for RuÃRu bond lengths [13].
/
Complex 3 has previously been obtained as a product
from the reaction of [Ru3(CO)12] with [Cr(AsPhH2)-
(CO)5] although no experimental nor spectroscopic
principal difference between 4×
/
2CH2Cl2 and 4 [15] is
Fig. 3. Molecular structure of [Ru6(m4-PPh)3(m3-PPh)2(CO)12] (4×
/2CH2Cl2) including the atom numbering scheme. All hydrogen atoms have been
omitted for clarity.

32
R.M. De Silva et al. / Journal of Organometallic Chemistry 664 (2002) 27Á36
/
Table 4
Evans and coworkers reported the synthesis of 6 from
the reaction of [Fe3(CO)12] with phenylphosphine [16]
and thus 6 has been identified on the basis of the close
similarity of the spectroscopic data. However, in the
case of 5 no previous spectroscopic data were available
due to the low yields of the reaction methods employed
[17,18].
In the IR spectrum of 5, three strong bands are seen in
the terminal carbonyl region due to the presence of the
nine carbonyl groups in a pattern that is closely related
to that for 6. The 13C{1H}-NMR spectrum of 5 displays
a sharp peak at d 214.0 and a broad peak at d 207.0 for
the nine terminal carbonyl ligands in addition to the
phenyl resonances. A similar pair of signals in the
carbonyl region has also been observed for 6, in which
the sharp signal has been assigned to a rotating central
Fe(CO)3 group and the broader resonance to inter-
mediate exchange behaviour involving more restricted
localised rotation of the two outer Fe(CO)3 units [16]. It
is likely that a similar mechanism is also operating for 5.
The FAB mass spectrum of 5 shows a molecular ion
peak along with fragmentation peaks corresponding to
the loss of up to nine carbonyl groups.
Complex 7 has been characterised on the basis of the
close similarity of the spectroscopic properties with
those previously reported [19]. In addition, the unit
cell dimensions of a single crystal obtained in this work
are closely related to the crystallographically determined
structure of 7 [20]. Notably, West and Ang prepared 7 as
the sole product from the reaction of [Fe(CO)5] with
either cyclo-(PhP)4 or cyclo-(PhP)5 in a sealed tube at
elevated temperature. However, employment of the
larger CPP, 1b, under similar conditions has furnished
7 along with two other complexes (6 and 8), all resulting
from fragmentation of the CPP ring.
˚
Selected bond distances (A) and angles (8) for 4×2CH2Cl2
Bond distances
Ru(1)ÃRu(2)
Ru(1)ÃRu(3)
Ru(1)ꢀ ꢀ ꢀRu(1A)
Ru(2)ÃRu(3A)
Ru(2A)ÃRu(3)
Ru(2)ꢀ ꢀ ꢀRu(3)
Ru(1)ÃP(3)
2.895(1) Ru(2)ÃP(1)
2.900(1) Ru(2)ÃP(3A)
3.265(1) Ru(2)ÃP(2)
2.937(1) Ru(3)ÃP(1)
2.937(1) Ru(3)ÃP(2)
3.417(2) Ru(3)ÃP(3)
2.481(2)
2.358(3)
2.277(3)
2.474(2)
2.288(3)
2.352(3)
2.431(3) Mean RuÃC(carbonyl) 1.90
2.306(3)
Ru(1)ÃP(2)
Bond angles
Ru(1)ÃRu(2)ÃRu(3)
53.9(1) Ru(2)ÃP(1)ÃRu(3)
72.7(1)
Ru(1)ÃRu(2)ÃRu(3A) 93.3(1) Ru(2)ÃRu(1)ÃRu(3)
Ru(1)ÃRu(3)ÃRu(2) 53.8(1) Ru(2)ÃRu(1)ÃRu(1A)
Ru(1)ÃRu(3)ÃRu(2A) 93.3(1) Ru(2)ÃRu(3)ÃRu(2A)
Ru(1)ÃP(2)ÃRu(3)
Ru(1)ÃP(3)ÃRu(3)
Ru(1)ÃP(2)ÃRu(2)
72.3(1)
86.8(1)
90.1(1)
74.3(1)
77.1(1)
78.3(1) Ru(2)ÃP(3A)ÃRu(1)
74.6(1) Ru(3)ÃP(3)ÃRu(2A)
78.4(1)
that in the solvate form the molecule lies on a crystal-
lographically twofold axis passing through P(1), C(19)
and C(22). This has the effect that in 4×
distortion or expansion of the metal atom framework
from a regular trigonal prismatic geometry occurs
symmetrically about the twofold axis through P(1)
/
2CH2Cl2 the
[Ru(2)Ã
/
Ru(3) 3.417(2) and Ru(3A)Ã
/
Ru(2A) 3.417(2)
A]. On the other hand, in 4 [15] the expansion occurs
˚
unsymmetrically with the elongation of the correspond-
˚
ing rutheniumÁruthenium edges differing by 0.186 A. In
/
addition, the Ru(1)ꢀ ꢀ ꢀRu(1A) non-bonded distance
˚
[3.265(1) A] in 4×
/
2CH2Cl2, which corresponds to an
axial edge of the trigonal prism, is marginally longer
˚
than in the non-solvated form [3.323(3) A].
The spectroscopic properties of 4 are consistent with
those previously reported. It is noteworthy that the yield
of 25% for 4 obtained using the methodology described
in this paper is an improvement on that previously
reported (15%), in which 4 was prepared from the
reaction of [Ru3(CO)12] with three equivalents of
phenylphosphine [15].
The molecular structure of 8 is shown in Fig. 4 while
selected bond distances and angles are collected in Table
Table 5
˚
Selected bond distances (A) and angles (8) for 8
2.2. Reaction of [Fe3(CO)12] with cyclo-(PhX)6 (Xꢀ
/
Bond distances
As 1a, P 1b)
Fe(1)ÃFe(2)
Fe(3)ÃFe(4)
P(1)ÃP(2)
2.732(2) Fe(3)ÃP(2)
2.738(2) Fe(4)ÃP(2)
2.232(3) Fe(1)ÃP(4)
2.205(3) Fe(3)ÃP(4)
2.206(3) Fe(2)ÃP(3)
2.200(3) Fe(4)ÃP(3)
1.78
2.210(3)
2.205(2)
2.347(3)
2.313(3)
2.319(3)
2.352(3)
The reaction of 1a with two equivalents of Fe3(CO)12
in toluene at elevated temperature gives [Fe3(m3-As-
Ph)2(CO)9] (5) in good yield. The corresponding reac-
tion of 1b affords the complexes [Fe3(m3-PPh)2(CO)9]
(6), [Fe2(m-h2-catena-(P4Ph4)}(CO)6] (7) and [Fe2{m4-
(P2Ph2)}(CO)6]2 (8) in overall moderate yield (Scheme
1). All the complexes have been characterised by IR, 1H-
P(3)ÃP(4)
Fe(1)ÃP(1)
Fe(2)ÃP(1)
Mean FeÃC(carbonyl)
Bond angles
Fe(1)ÃP(1)ÃFe(2)
Fe(1)ÃP(4)ÃFe(3)
Fe(1)ÃFe(2)ÃP(3)
Fe(1)ÃP(4)ÃP(3)
Fe(2)ÃP(3)ÃFe(4)
Fe(2)ÃP(3)ÃP(4)
Fe(2)ÃFe(1)ÃP(4)
76.7(1) Fe(3)ÃP(4)ÃP(3)
119.2(1) Fe(3)ÃFe(4)ÃP(3)
84.9(1) Fe(4)ÃP(3)ÃP(4)
97.5(1) Fe(4)ÃFe(3)ÃP(4)
119.6(1) P(1)ÃP(2)ÃFe(4)
95.3(1) P(1)ÃP(2)ÃFe(3)
82.0(1)
95.5(1)
81.8(1)
97.5(1)
85.0(1)
111.0(1)
117.1(1)
,
and by elemental analysis (see Table 1).
31P- (6Á8), 13C-NMR spectroscopy, mass spectrometry
/
The isostructural trigonal bipyramidal complexes 5
and 6 have been previously synthesised by alternative
routes and crystallographically characterised [16Á18].
/

R.M. De Silva et al. / Journal of Organometallic Chemistry 664 (2002) 27Á
/36
33
obtainable and has related its structure to the hydro-
carbon cuneane [22].
The IR spectrum of 8 exhibits three strong bands and
one medium intensity band in the terminal n(CO) region
due to the presence of the 12 carbonyl groups. These
values are consistent with the pattern of bands observed
for the related complex [(OC)3FePMe]4 [21c]. The
13C{1H}-NMR spectrum at room temperature shows,
in addition to signals for the four phenyl groups, four
broad resonances at d 213.0, 211.0, 209.0 and 207.0 due
to the terminal carbonyl groups. It would seem likely
that at this temperature a fluxional process is operating.
In the 31P{1H}-NMR spectrum of 8, two triplets at d
536.0 and 233.0 [2J(PP) 174 Hz] correspond to the four
phosphorus atoms of the two P2Ph2 groups suggesting
that two phosphorus atoms on a given P2Ph2 ligand are
equivalent to each other. The FAB mass spectrum of 5
shows a molecular ion peak along with fragmentation
peaks corresponding to the loss of up to 12 carbonyl
groups.
Given the propensity of 1a or 1b to act as sources of
AsPh and PPh fragments when reacted with
[Fe3(CO)12], we decided to attempt a preparation of an
iron complex containing both AsPh and PPh ligands.
The reaction of [Fe3(CO)12] with 1a and 1b in a 2:1:1
molar ratio at elevated temperature gave 5, 6 and
[Fe3(m3-PPh)(m3-AsPh)(CO)9] (9) in moderate overall
yield (Scheme 1). All three complexes have the same
retention factor (Rf) and could not be separated by
chromatographic means. However, the presence of the
three complexes could be identified from the spectro-
scopic data and by comparing these data with those for
the already characterised complexes 5 and 6. For
example, in the 31P{1H}-NMR spectrum of the mixture,
an additional peak for the PPh ligand in 9 is seen at d
339.4. The FAB mass spectrum displays molecular ion
peaks for 5 and 6 along with that for 9 in addition to
fragmentation peaks corresponding to carbonyl losses
for each complex.
Fig. 4. Molecular structure of [Fe2{m4-(P2Ph2)}(CO)6]2 (8) including
the atom numbering scheme. All hydrogen atoms have been omitted
for clarity.
5. Crystals suitable for the analysis were grown by
diffusion of hexane into a dichloromethane solution of 8
at 0 8C. The molecule is constructed from two discrete
metalÃ
two diphenyldiphosphane groups. One of the P2Ph2
moieties bridges the FeÃFe vectors perpendicularly with
/metal bonded Fe2(CO)6 units linked together by
/
each phosphorus atom [P(1), P(2)] bonded to both iron
atoms of a particular Fe2(CO)6 unit. The other P2Ph2
moiety bridges the FeÃ
/
Fe vectors in a parallel bonding
mode with each phosphorus atom [P(3), P(4)] linked to
metal atoms belonging to different Fe2(CO)6 units. The
˚
Fe iron bond lengths [2.732(2), 2.738(2) A] fall into
FeÃ
/
3. Summary
the typical range for complexes of a similar type and the
˚
average FeÃ
observed for other bridging diphosphane and phosphido
groups bound to an iron carbonyl moiety [21]. The PÃ
bond lengths of 2.232(3) and 2.205(3) A are consistent
with single bonds between the two atoms.
Complex 8 can be considered as belonging to a family
of compounds of general formula [(OC)3FePR]4. Indeed
Vahrenkamp and coworker have structurally charac-
terised the complex [(OC)3FePMe]4, which can be
viewed as a structural isomer of 8, in which both
diphosphane ligands perpendicularly bridge both
Fe2(CO)6 units [21c]. Indeed Vahrenkamp has pre-
viously suggested that a complex of type 8 should be
/
P bond length of 2.27 A, is in the range
The reactions of the hexaphenyl cyclo-hexaarsane 1a
and cyclo-hexaphosphane 1b with a ruthenium cluster
containing labile ligands, [Ru3(CO)10(NCMe)2], lead to
the products 2a and 2b in which the six-membered rings
of the ligands remain intact. However, notable differ-
ences are observed in the outcome of the reactions of 1a
and 1b with metal clusters containing only carbonyl
ligands. Thus, the reactions of 1a with [Ru3(CO)12] and
[Fe3(CO)12] yield the complexes 3 and 5, respectively,
containing triply-bridging phenylarsenidene units as the
sole Group 15 ligand, indicating extensive disruption of
the hexameric arsenic ring. In contrast, the reactions of
1b with [Ru3(CO)12] and [Fe3(CO)12] under similar
/P
˚

34
R.M. De Silva et al. / Journal of Organometallic Chemistry 664 (2002) 27Á36
/
conditions yield 4, 6, 7 and 8, in which varying degrees
of fragmentation of the cyclic phosphorus rings occur.
orange crystalline [Ru3{m-cyclo-(PhP)6}(CO)10] (2b)
(0.07 g, 63%).
Finally, a mixed arsenideneÁphosphinidene iron com-
/
plex 9 has been shown to be accessible.
4.3. Synthesis of 3
The complex [Ru3(CO)12] (0.159 g, 0.25 mmol) and 1a
(0.23 g, 0.25 mmol) were dissolved in C6H5CH3 (10 ml)
4. Experimental
and the reaction vessel evacuated with three freezeÁ
/
4.1. General techniques
pumpÁthaw cycles then sealed under reduced pressure.
/
The reaction mixture was stirred at 70 8C for 24 h.
After cooling the reaction vessel was opened and the
solution filtered. Following removal of the solvent under
reduced pressure, the residue was redissolved in CH2Cl2,
silica added and the mixture pumped dry. The solid was
added to the top of a silica chromatography column;
elution with C6H14 gave unreacted [Ru3(CO)12] and the
dark yellow crystalline compound [Ru4(m3-PhAs)2-
(CO)13] (3) (0.025 g, 9%).
All reactions were carried out under an atmosphere of
dry, oxygen-free nitrogen, using standard Schlenk
techniques. Solvents were distilled under nitrogen from
appropriate drying agents and degassed prior to use [23].
IR spectra were recorded in C6H14 solution in 0.5 mm
NaCl cells, using a PerkinÁElmer 1710 Fourier-trans-
/
form spectrometer. Fast atom bombardment (FAB)
mass spectra were recorded on a Kratos MS 890
instrument using 3-nitrobenzyl alcohol as a matrix.
Proton (reference to SiMe4), 31P- and 13C-NMR spectra
were recorded on either a Bruker WM250 or AM400
spectrometer, 31P-NMR chemical shifts are referenced
to 85% H3PO4. Preparative thin-layer chromatography
(TLC) was carried out on commercial Merck plates with
a 0.25 mm layer of silica, or on 1 mm silica plates
prepared at the Department of Chemistry, Cambridge.
Column chromatography was performed on Kieselgel
4.4. Synthesis of 4
To a solution of [Ru3(CO)12] (0.20 g, 0.31 mmol) in
C7H16 (50 ml) was added 1b (0.20 g, 0.30 mmol) and the
resulting solution heated to reflux for 5 h. The solution
was then cooled to room temperature (r.t.) and filtered.
After removal of the solvent under reduced pressure, the
residue was dissolved in the minimum volume of
CH2Cl2 and applied to the base of TLC plates. Elution
60 (70Á
/
230 or 230Á400 mesh). Products are given in
/
order of decreasing Rf values. Elemental analyses were
performed at the Department of Chemistry, Cambridge.
Unless otherwise stated all reagents were obtained
from commercial suppliers and used without further
purification. The syntheses of [Ru3(CO)10(NCMe)2] [24],
1a [25] and 1b [26] have been reported previously.
with C6H14ÁCH2Cl2 (4:1) gave unreacted starting ma-
/
terial, green [Ru6(m4-PPh)3(m3-PPh)2(CO)12] (4) (0.005 g,
12%) and trace quantities of uncharacterised red and
brown compounds.
4.5. Synthesis of 5
4.2. Synthesis of 2
To a solution of 1a (0.456 g, 0.5 mmol) in C6H5CH3
(50 ml) was added [Fe3(CO)12] (0.510 g, 1.0 mmol). The
solution was heated to 90 8C for 5 h. The solution was
then cooled to r.t. and filtered. After removal of the
solvent under reduced pressure, the residue was redis-
solved in CH2Cl2, silica added and the mixture pumped
dry. The solid was added to the top of a silica
4.2.1. Complex 2a
To a solution of [Ru3(CO)10(NCMe)2] (0.131 g, 0.2
mmol) in C6H5CH3 (50 ml) was added 1a (0.183 g, 0.20
mmol) and the resulting solution stirred at ambient
temperature for 6 h. After removal of solvent at reduced
pressure, the residue was dissolved in the minimum
volume of CH2Cl2 and applied to the base of preparative
chromatography column and elution with C6H14Á
/
CH2Cl2 (4:1) gave [Fe3(m3-AsPh)2(CO)9] (5) (0.219 g,
65%).
TLC plates. Elution using C6H14Á
/CH2Cl2 (4:1) gave
reddishÁorange crystalline [Ru3{m-cyclo-(PhAs)6}-
/
(CO)10] (2a) (0.20 g, 67%).
4.6. Synthesis of 6, 7 and 8
4.2.2. Complex 2b
[Fe3(CO)12] (0.504 g, 1.0 mmol) and 1b (0.324 g, 0.50
mmol) were dissolved in C6H5CH3 (10 ml); the reaction
To a solution of [Ru3(CO)10(NCMe)2] (0.061 g, 0.09
mmol) in C6H6 (50 ml) was added 1b (0.065 g, 0.10
mmol) and the resulting solution stirred at ambient
temperature overnight. After removal of the solvent
under reduced pressure, the residue was dissolved in the
minimum volume of CH2Cl2 and purified by preparative
vessel was then evacuated with three freezeÁ
/
pumpÁthaw
/
cycles and sealed under reduced pressure. The mixture
was stirred at 90 8C for 24 h and, after cooling, the
vessel was then opened and the solution filtered. After
removal of the solvent under reduced pressure, the
residue was dissolved in the minimum volume of
TLC. Elution using C6H14ÁCH2Cl2 (4:1) gave dark
/

R.M. De Silva et al. / Journal of Organometallic Chemistry 664 (2002) 27Á
/36
35
Table 6
Crystallographic and data processing parameters for complexes 2a, 3, 4×2CH2Cl2 and 8
Complex
2a
3
4
8
Empirical formula
M
C
46H30As6O10Ru3
C25H10As2O13Ru4
1072.45
150(2)
C42H26O12P5Ru6×2CH2Cl2 C36H20Fe4O12P4
1495.43
293(2)
Monoclinic
P21/n
1653.75
150(2)
991.80
180(2)
Temperature (K)
Crystal system
Space group
Monoclinic
P21/c
Monoclinic
C2/c
Monoclinic
P21/n
Lattice parameters
˚
a (A)
˚
13.043(5)
22.614(5)
17.244(5)
90
11.430(4)
16.968(3)
16.110(3)
90
13.030(3)
27.338(3)
16.832(40)
90
10.7290(10)
16.1130(10)
24.1250(10)
90
b (A)
˚
c (A)
a (8)
b (8)
g (8)
100.44(3)
90
5002
92.02(2)
90
107.45(2)
90
96.380(10)
90
3
˚
U (A )
Z
3122.5(14)
4
2.281
5720(2)
4
1.920
4144.8(5)
4
1.589
4
1.986
Dcalc (mg mꢃ3
)
m(MoÁ
F(000)
Crystal size (mm)
/
Ka) (mmꢃ1
)
4.877
2864
4.063
2024
1.924
3188
1.584
1984
0.15ꢄ0.10ꢄ0.05
6530
6208
0.20ꢄ0.18ꢄ0.10
5782
5489
0.20ꢄ0.10ꢄ0.10
6853
6571
0.20ꢄ0.10ꢄ0.10
18 963
6636
Reflections collected
Independent reflections
Rint
0.037
586/0
0.044
397/0
0.085
306/3
0.088
505/0
Parameters/restraints
Final R indices [I ꢀ2s(I)]
All data
Goodness-of-fit on F2 (all data) 1.045
R1ꢀ0.0501, wR2ꢀ0.1172 R1ꢀ0.0458, wR2ꢀ0.0940 R1ꢀ0.0597, wR2ꢀ0.1306 R1ꢀ0.0558, wR2ꢀ0.1385
R1ꢀ0.0712, wR2ꢀ0.1302 R1ꢀ0.0743, wR2ꢀ0.1063 R1ꢀ0.1778, wR2ꢀ0.2184 R1ꢀ0.1434, wR2ꢀ0.1651
1.048
1.006
0.996
2
2
1=2
2
2
2
˚
Data in common: graphite-monochromated MoÁ
/
Ka radiation, lꢀ0.71073 A; R1ꢀa jjFojꢃjFcjj/a jFoj, wR2 ꢀ[a w(Fo ꢃFc ) =a w(Fo ) ]
;
wꢃ1ꢀ[s2(Fo)2ꢂ(aP)2], Pꢀ[max(Fo2; 0)ꢂ2(Fc2)]=3; where a is a constant adjusted by the program; goodness-of-fitꢀ[a (Fo2 ꢃFc2)2=(nꢃp)]1=2 where
n is the number of reflections and p the number of parameters.
CH2Cl2 and separated by preparative TLC. Elution
using C6H14ÁCH2Cl2 (4:1) gave orange crystalline
[Fe3(m3-PPh2)2(CO)9] (6) (0.04 g, 15%), yellow crystalline
[Fe2{m-h2-catena-(P4Ph4)}(CO)6] (7) (0.02 g, 7%) and
orange crystalline [Fe2{m4-(P2Ph2)}(CO)6]2 (8) (0.02 g,
5%).
ometers (8). Both systems were equipped with an Oxford
Cryosystems Cryostream. Details of data collection,
refinement and crystal data are listed in Table 6.
Semiempirical absorption corrections based on 8-scan
data were applied [27,28] to the data for 2a, 3, 4 and 7.
No absorption correction was applied to the data for 8.
/
The structures were solved by direct methods (SHELXS
-
86 [29]) and subsequent Fourier-difference syntheses and
refined anisotropically on all ordered non-hydrogen
4.7. Synthesis of 9
atoms by full-matrix least-squares on F2
(SHELXL-93
[Fe3(CO)12] (0.504 g, 1.0 mmol), 1b (0.324 g, 0.50
mmol) and 1a (0.324 g, 0.50 mmol) were dissolved in
C6H5CH3 (15 ml); the reaction vessel was then evacu-
[30]). Hydrogen atoms were placed in geometrically
idealised positions and refined using a riding model. In
the final cycles of refinement a weighting scheme was
introduced which produced a flat analysis of variance.
ated with three freezeÁ
/
pumpÁthaw cycles and sealed
/
under reduced pressure. The mixture was stirred at
90 8C for 24 h; after cooling the vessel was then opened
and the solution filtered. After removal of the solvent
under reduced pressure, the residue was dissolved in the
minimum volume of CH2Cl2 and separated by prepara-
5. Supplementary material
tive TLC. Elution using C6H14ÁCH2Cl2 (4:1) gave a
/
mixture of [Fe3(m3-AsPh)2(CO)9] (5), [Fe3(m3-PPh2)2-
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
(CO)9] (6) and [Fe3(m3-AsPh2)(m3-PPh2)(CO)9] (9) as a
redÁorange solid (0.133 g).
/
Data Centre, CCDC nos. 184273Á
/
184276 for com-
pounds 2a, 3, 4×2CH2Cl2 and 8. Copies of this informa-
tion may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
/
4.8. Crystallography
X-ray intensity data was collected using Rigaku
AFC7R (2a, 3, 4) and RAXIS-IIC image plate diffract-
(Fax: ꢂ
/
44-1223-336033; e-mail: deposit@ccdc.cam.a-
c.uk or www: http://www.ccdc.cam.ac.uk).

36
R.M. De Silva et al. / Journal of Organometallic Chemistry 664 (2002) 27Á36
/
[6] R.M. De Silva, M.J. Mays, G.A. Solan, unpublished results.
[7] R.M. De Silva, M.J. Mays, P.R. Raithby, G.A. Solan, J.
Organomet. Chem. 625 (2001) 245.
Acknowledgements
We gratefully acknowledge the financial support of
the Cambridge Commonwealth Trust and the United
Kingdom Committee of Vice Chancellors and Principals
(to R.M.D.S.). Thanks is also due to Dr J.E. Davis for
collection of the X-ray data.
[8] R.M. De Silva, M.J. Mays, P.R. Raithby, G.A. Solan, J.
Organomet. Chem. 642 (2002) 237.
[9] (a) K. Hedberg, E.W. Hughes, J. Waser, Acta Crystallogr. 14
(1961) 369;
(b) A.L. Rheingold, P.J. Sullivan, Organometallics 2 (1983) 327.
[10] (a) S.G. Teoh, H.K. Fun, O.B. Shawkataly, Z. Kristallogr. 190
(1990) 287;
(b) P.J. Roberts, J. Trotter, J. Chem. Soc. Sect. A (1971) 1479;
(c) P.J. Roberts, J. Trotter, J. Chem. Soc. Sect. A (1970) 3246.
[11] (a) G. Lavigne, N. Lugan, J.-J. Bonnet, Organometallics 1 (1982)
1040;
References
[1] (a) A.-J. DiMaio, A.L. Rheingold, Chem. Rev. 90 (1990) 169;
(b) A.L. Rheingold, in: A.L. Rheingold (Ed.), Homoatomic
Rings, Chains and Macromolecules of the Main-Group Elements,
Elsevier, Amsterdam, 1977, p. 385.
(b) O.B. Shawkataly, K. Ramalingam, S.T. Lee, M. Parameswary,
H.K. Fun, K. Sivakumar, Polyhedron 17 (1998) 1211.
[12] M.R. Churchill, F.J. Hollander, J.P. Hutchinson, Inorg. Chem. 16
(1977) 2655.
[2] For reactions involving CPAs see for example: (a) A.L. Rhein-
gold, M.E. Fountain, Organometallics 5 (1986) 2410;
(b) A.L. Rheingold, M.E. Fountain, A.J. DiMaio, J. Am. Chem.
Soc. 109 (1987) 141;
[13] The ‘normal’ range for RuÃ
/
Ru bonds are in the range 2.70Á2.95
/
˚
A, see: H.-G. Ang, S.-G. Ang, S.-W. Du, B.-H. Sow, A.L.
Rheingold, J. Organomet. Chem. 510 (1996) 13 (and references
therein),
(c) P.S. Elmes, B.O. West, Aust. J. Chem. 23 (1970) 2247;
(d) P.S. Elmes, B.M. Gatehouse, D.J. Lloyd, B.O. West, J. Chem.
Soc. Chem. Commun. (1974) 953;
[14] J.S. Field, R.J. Haines, D.N. Smit, K. Natarajan, O. Scheidsteger,
G. Huttner, J. Organomet. Chem. 2140 (1982) C23.
[15] J.S. Field, R.J. Haines, D.N. Smit, J. Chem. Soc. Dalton Trans.
(1988) 1315.
(e) P.S. Elmes, B.O. West, J. Organomet. Chem. 32 (1971) 365;
(f) P.S. Elmes, P. Laverett, B.O. West, J. Chem. Soc. Chem.
Commun. (1971) 747;
[16] S.L. Cook, J. Evans, L.R. Gray, M. Webster, J. Organomet.
Chem. 236 (1982) 367.
(g) A.L. Rheingold, M.J. Foley, P.J. Sullivan, Organometallics 1
(1982) 1429;
[17] G. Huttner, G. Mohr, A. Frank, U. Schubert, J. Organomet.
Chem. 118 (1976) C73.
(h) A.L. Rheingold, M.R. Churchill, J. Organomet. Chem. 243
(1983) 165;
[18] M. Jacob, E. Weiss, J. Organomet. Chem. 131 (1977) 263.
[19] H.-G. Ang, B.O. West, Aust. J. Chem. 20 (1967) 1133.
[20] A.L. Rheingold, M.E. Fountain, Organometallics 3 (1984) 1417.
[21] See for example: (a) H. Vahrenkamp, D. Wolters, Angew Chem.
Int. Ed. Engl. 22 (1983) 154;
(i) B.M. Gatehouse, J. Chem. Soc. Chem. Commun. (1969) 948;
(j) A.L. Rheingold, P.J. Sullivan, J. Chem. Soc. Chem. Commun.
(1983) 39;
(k) A.L. Rheingold, P.J. Sullivan, Organometallics 1 (1982) 1547;
(l) L.F. Dahl, A.S. Foust, M.S. Foster, J. Am. Chem. Soc. 24
(1969) 5631.
(b) E.P. Kyba, K.L. Hassett, B. Sheikh, J.S. McKennis, R.B.
King, R.E. Davis, Organometallics 4 (1985) 994;
(c) R.L. De, H. Vahrenkamp, Angew. Chem. Int. Ed. Engl. 23
(1984) 983;
[3] For reactions involving CPPs see for example: (a) H.-G. Ang, L.-
L. Koh, Q. Zhang, J. Chem. Soc. Dalton Trans. (1995) 2757;
(b) H.-G. Ang, S.-G. Ang, Q. Zhang, J. Chem. Soc. Dalton Trans.
(1996) 2773;
(d) W. Clegg, Inorg. Chem. 15 (1976) 1609.
[22] L.R. Smith, J. Chem. Edu. 55 (1978) 569.
[23] W.L.F. Armarego, D.D. Perrin, Purification of Laboratory
Chemicals, 4th ed., Butterworth, Heinemann, 1996.
[24] G.A. Foulds, B.F.G. Johnson, J. Lewis, J. Organomet. Chem. 296
(1985) 147.
(c) H.-G. Ang, S.-G. Ang, Q. Zhang, J. Chem. Soc. Dalton Trans.
(1996) 3843;
(d) H.-G. Ang, K.-W. Ang, S.-G. Ang, A.L. Rheingold, J. Chem.
Soc. Dalton Trans. (1996) 3131;
(e) R.A. Bartlett, H.V.R. Dias, K.M. Flynn, H. Hope, B.D.
Murray, M.M. Olmstead, P.P. Power, J. Am. Chem. Soc. 109
(1987) 5693;
[25] (a) K. Hedberg, E.W. Hughes, J. Waser, Acta Crystallogr. 14
(1961) 369;
(b) A.L. Rheingold, P.J. Sullivan, Organometallics 2 (1983) 327.
[26] (a) J.J. Daly, J. Chem. Soc. Sect. A (1966) 428;
(b) J.J. Daly, J. Chem. Soc. (1965) 4789.
(f) M. Bandler, F. Slazer, J. Hahn, E. Darr, Angew. Chem. Int.
¨
Ed. Engl. 24 (1985) 415;
(g) B.F.G. Johnson, T.M. Layer, J. Lewis, P.R. Raithby, W.-T.
Wong, J. Chem. Soc. Dalton Trans. (1993) 973.
[27] TEXSAN, Version 1.1-1, Molecular Structure Corporation, The
Woodlands, TX, 1985, 1992, 1995.
[4] Most previous studies (see Refs. [1Á3]) of CPAs and CPPs have
/
[28] A.C.T. North, D.C. Philips, F.S. Mathews, Acta Crystallogr.
Sect. A 24 (1968) 351.
[29] G.M. Sheldrick, SHELXS-86, University of Gottingen, 1993.
¨
been performed using elevated temperatures and/or in sealed
vessels.
[5] R.M. De Silva, M.J. Mays, J.E. Davies, P.R. Raithby, M.A.
Rennie, G.P. Shield, J. Chem. Soc. Dalton Trans. (1998) 439.
[30] G.M. Sheldrick, SHELXL-93, University of Gottingen, 1993.
¨