Adducts of cyclotriphosphorus complexes with cyclopentadienyl ruthenium fragments: Synthesis, solid-state structure and solution behaviour

Article abstract of DOI:10.1002/ejic.200400847

Treatment of the cyclo-P₃ complexes [(triphos) M(η³-P₃)]-[triphos = 1,1,1- tris(diphenylphosphanylmethyl)ethane; M = Co (1), Rh (2)] with stoichiometric amounts of [CpRu-(CH₃CN)₂(PR₃)]PF

Full text of DOI:10.1002/ejic.200400847

FULL PAPER
Adducts of Cyclotriphosphorus Complexes with Cyclopentadienyl Ruthenium
Fragments: Synthesis, Solid-State Structure and Solution Behaviour
Pierluigi Barbaro,[b] Massimo Di Vaira,[a] Maurizio Peruzzini,[b]
Stefano Seniori Costantini,[a] and Piero Stoppioni*[a]
Keywords: Cyclotriphosphorus / Ruthenium / Cyclopentadienyl / Monodentate P ligands
Treatment of the cyclo-P3 complexes [(triphos)M(η3-P3)]-
[triphos = 1,1,1-tris(diphenylphosphanylmethyl)ethane; M =
Co (1), Rh (2)] with stoichiometric amounts of [CpRu-
(CH3CN)2(PR3)]PF6 [R = Ph (3), Me (4), Cy (5)] in CH2Cl2 in
the presence of CH3CN yields the bimetallic adducts
[{(triphos)M}(μ,η3:1-P3){CpRu(CH3CN)(PR3)}]PF6 [M = Co; R =
Ph (6), Me (7), Cy (8); M = Rh; R = Ph, (9), Me (10), Cy (11)].
The rhodium derivatives 9 and 11, upon treatment with one
P3){CpRu(PR3)}]PF6 [R = Ph (14), Me (15)]. All the compounds
have been characterised by elemental analyses and, in solu-
tion, by 31P and 1H NMR spectroscopy. The 31P{1H} EXSY
NMR spectroscopic data at different temperatures of 11 and
14 have highlighted the occurrence of independent dynamic
processes that exchange both the triphos and the cyclo-P3
phosphorus nuclei. An X-ray structural investigation carried
out on 6 has confirmed the occurrence of the μ,η3:1-ligating
behaviour of the cyclo-P3 ligand.
equivalent of PMe3, form the complexes [{(triphos)Rh}(μ,η3:1
-
P3){CpRu(PMe3)(PR3}]PF6 [R = Ph (12), Cy (13)]. On standing
in CH2Cl2, the rhodium complexes 9 and 10 lose acetonitrile
to yield compounds with the formula [{(triphos)Rh}(μ,η3:1,1Ј-
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
tris(diphenylphosphanylmethyl)ethane (triphos) ligand
(Scheme 1).[26,27]
Introduction
“Naked” group 15 ligands stabilised by transition-metal
moieties exhibit lone pair electrons, owing to which they are
generally endowed with reactivity toward metal fragments
with Lewis acid character. Many compounds have been de-
scribed that result from the addition of metal moieties,
mainly carbonyl or cyclopentadienyl carbonyl metal frag-
ments, to the above metal-supported main group atom li-
gands. The added moieties, depending on their ligating
properties, may bind in η1-, η2- or η3 fashion to the main
group units to afford bi-, tri- and tetrametallic com-
plexes.[1–5] The solution structures of these multimetallic ad-
ducts may usually be assigned by in-depth 31P NMR spec-
troscopic studies. These NMR studies have often revealed
the occurrence of a dynamic behaviour consisting of (i)
skeleton rearrangements of multinuclear cluster com-
pounds,[6–12] (ii) relative rotation of parts of the molecule
about symmetry- or pseudosymmetry axes,[13–16] and (iii)
scrambling of coordinated fragments.[17,18] In our laborato-
ries the reactivity of a series of neutral[19–21] and cat-
ionic[22–25] complexes has been investigated, in which a cy-
clic triatomic E3 or E2X (E = P, As; X = S, Se) group isη3
bound to a metal atom of the cobalt or of the nickel group
and is supported by the tripodal tridentate 1,1,1-
Scheme 1.
The neutral compounds [(triphos)M(η3-P3)] (M = Co,
Rh) easily add coordinatively unsaturated metal fragments,
such as M(CO)5 (M = Cr, W) or CpMn(CO)2, to yield bi-,
tri- and tetrametallic adducts in which the geometry of the
P3 ring is only slightly modified from that in the parent
compounds.[19,21,28–31] In contrast, the cationic [(triphos)-
M(η3-E2X)]+ species (M = Ni; E = X = P. M = Co; E = P,
As; X = S, Se) do not add carbonyl fragments, but readily
insert the 14e M(PPh3)2 (M = Pd, Pt) carbene-like moieties
into an E–E or E–X bond of the triatomic ring.[31–33] Inter-
estingly, all of these polymetallic compounds exhibit dy-
namic behaviour at room temperature. Recent studies on a
series of complexes resulting from the addition of one me-
[a] Dipartimento di Chimica, Università di Firenze,
via della Lastruccia, 3, 50019 Sesto Fiorentino, Firenze, Italy
[b] ICCOM-CNR,
via Madonna del Piano snc, 50019 Sesto Fiorentino, Firenze,
Italy
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejic.200400847
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Adducts of Cyclotriphosphorus Complexes with Cyclopentadienyl Ruthenium Fragments
FULL PAPER
tal-carbonyl fragment to [(triphos)M(η3-P3)] (M = Co, Rh)
Results and Discussion
have definitely shown that two fluxional processes occur in
solution, i.e. the scrambling of the metal-carbonyl moiety
over the P3 cyclic system and the relative rotation of the P3
and {(triphos)M} moieties about their common C3 axis.[34]
Variable-temperature NMR analysis has also established
that the rhodium derivatives have a higher rotational barrier
than the cobalt derivatives.[34] The scrambling process over
cyclo-P3, which has been blocked at low temperature for
both cobalt and rhodium derivatives, has a higher barrier
with respect to the {(triphos)M} rotation. Indeed, the latter
process has been blocked on the NMR time scale only for
the rhodium adduct [{(triphos)Rh}(μ,η3:1-P3){W(CO)4-
PPh3}], which is formed with the sterically demanding
W(CO)4(PPh3) fragment sitting as an end-on ligand on the
cyclotriphosphorus unit.[34]
In this work we have investigated the reactivity of
[(triphos)M(η3-P3)] [M = Co (1), Rh(2)] toward the
[CpRu(CH3CN)2(PR3)]PF6 [R = Ph (3), Me (4), Cy (5)]
complexes. These species contain two acetonitrile molecules
that can be selectively replaced to generate the 16e
[CpRu(CH3CN)(PR3)]+ and 14e [CpRu(PR3)]+ fragments,
respectively.[35] The 16e moieties appear to be particularly
suitable, upon reaction with 1 and 2, to provide further in-
formation on the factors affecting the scrambling process
of the metal fragment, as they are more sterically hindered
than the carbonyl moieties previously employed and,
furthermore, their steric demand may be varied by changing
the phosphane substituents. Moreover, the lability of the
The dinuclear compounds with the formula [{(triphos)-
M}(μ,η3:1-P3){CpRu(CH3CN)(PR3)}]PF6 [M = Co; R = Ph
(6), Me (7), Cy (8); M = Rh; R = Ph, (9), Me (10), Cy
(11)] are obtained in a straightforward manner by adding a
stoichiometric amount of the appropriate [CpRu(CH3-
CN)2(PR3)]PF6 complex to [(triphos)M(η3-P3)] [M = Co
(1), Rh (2)] dissolved in CH2Cl2 in the presence of CH3CN
(see the Experimental Section). The complexes 6–11 can be
regarded as the mono adducts of the cyclo-P3 unit in 1 or
2 with 16e [CpRu(CH3CN)(PR3)]+ (R = Ph, Me, Cy) frag-
ments that readily result from the removal of one labile ace-
tonitrile molecule
from [CpRu(CH3CN)2(PR3)]PF6
(Scheme 2). The concentration of CH3CN is crucial for ob-
taining 6–11 in both high yield and purity. Actually, 1 and
2 do not react with the ruthenium complexes under condi-
tions of high CH3CN concentration, which hamper the sub-
stitution of the coordinating molecule that occurs through
a dissociative pathway.[35] The complexes 6–11 may be han-
dled in air for a limited time; they are soluble in polar or-
ganic solvents and their solutions are stable in an inert at-
mosphere. Solutions of 6–11, in both (CH3)2CO or CHCl3,
decompose when heated to 40–50 °C, yielding a mixture of
compounds, which could not be characterised.
X-ray Structure Analysis
The structure of 6, determined by X-ray crystal analysis,
second acetonitrile molecule may further extend the reactiv- consists
ity of the P3 ring, already activated by the initial end-on (PPh3)}]+ cations (Figure 1), PF6– anions, and toluene solv-
coordination of the ruthenium fragment. ate molecules in a 1:1:2 ratio. Selected values of bond
of
[{(triphos)Co}(μ,η3:1-P3){CpRu(CH3CN)-
Scheme 2. i) CH3CN, CH2Cl2, toluene; ii) CH2Cl2, PMe3, toluene; iii) CH2Cl2, toluene.
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P. Barbaro, M. Di Vaira, M. Peruzzini, S. Seniori Costantini, P. Stoppioni
FULL PAPER
lengths and angles are given in Table 1. In the dimetal cat- ruthenium atom; the opposite side of the coordination
ion, the {CpRu(CH3CN)(PPh3)} moiety forms through its sphere is occupied by the cyclopentadienyl ligand. A similar
metal atom an end-on monoadduct on a phosphorus atom coordination geometry, although in this case the nitrogen
of the CoP3 core. Such a pseudotetrahedral core exhibits atom of a second CH3CN ligand replaces the P3 phospho-
some deviations from the regular geometry of the parent rus atom, has recently been found for a ruthenium deriva-
compound 1, consisting of (i) a moderately shorter Co–P tive, in which the Ru–P(phosphane) and Ru–C(Cp) mean
bond formed by the bridging phosphorus atom [P(5)] be- distances are marginally shorter than the present ones and
tween the two metal atoms, with respect to the other two both Ru–N distances are longer by 0.05 Å.[37]
Co–P bonds, and (ii) slightly shorter P–P bonds formed by
the same P(5) atom than the third P–P bond in the P3 unit.
Consistent deviations from regularity have been detected
NMR Properties of the Compounds
for metal carbonyl monoadducts of 1 and 2[34] and similar,
although more pronounced, deviations have been found for
a methyl adduct.[36] Rationalizations for these trends have compounds 6–11 recorded in CD2Cl2 show resonances that
already been proposed.[13,34]
The room temperature 31P{1H} NMR spectra of the
fall into two quite distinct regions: a group of signals at low
field (50–2 ppm) is assigned to the phosphorus atoms of
triphos and of the phosphane bound to ruthenium (see Ex-
perimental Section), while a second group of high-field
shifted signals (from –150 to –304 ppm) is assigned to the
“naked” P atoms from the cyclo-P3 ligand. Table 2 presents
the NMR spectroscopic data for the latter resonances, and
the relevant labelling scheme is shown in Scheme 2. The in-
tensity ratios of the signals agree with the proposed formu-
lae. The resonance for the triphos phosphorus atoms exhib-
its chemical shifts that are similar to those of the parent
[(triphos)M(η3-P3)] [M = Co (1) and Rh (2)][22] compounds
and of other end-on carbonyl adducts.[13,34] The phospho-
rus atom of the PR3 ligand yields a doublet due to coupling
with PF; both the chemical shift and the coupling constant
of the phosphane ligand are in the range observed for
[CpRu(PR3)(PR3Ј)(L)] complexes.[38] This could indirectly
suggest that the donor/acceptor properties of the “naked”
phosphorus atoms in the “ligand” [(triphos)M(η3-P3)]
should be similar to those of the phosphanes. Signals due to
the P atoms of the cyclo-P3 unit are split into three distinct
multiplets in the high-field region with integral ratios of
1:1:1. Irrespective of the compound, the signal at lower field
appears as a triplet, while the other two, occurring at higher
field, consist each of a doublet of doublets, with small dif-
ferences in their chemical shifts. The overall high-field shifts
of the P atoms involved in the cyclo-P3 ring clearly suggest
that this unit has undergone only minor modifications upon
coordination to the ruthenium fragment. Indeed, severe re-
arrangements of the cyclic unit, such as cleavage of one of
its P–P bonds, significantly affect the chemical shifts, which
move to low field with respect to the signal of the parent
compound.[32] The multiplicities of the resonances under
discussion allow the safe assignment of the low-field triplet
to PF, which is slightly deshielded by coordination to the
ruthenium fragment. Consequently, the two high-field reso-
nances may be safely assigned to the two phosphorus atoms
Figure 1.
A
view
of
the
[{(triphos)Co}(μ,η3:1-P3)-
{CpRu(CH3CN)(PPh3)}]+ cation in the structure of 6; displace-
ment ellipsoids traced at the 20 % probability level. H atoms are
not shown and labels for the carbon atoms are omitted for clarity.
Table 1. Selected bond lengths [Å] and bond angles [°] for 6.
Bond lengths
Co–P(1)
Co–P(2)
Co–P(3)
Co–P(4)
Co–P(5)
Co–P(6)
P(4)–P(5)
2.178(5)
2.200(5)
2.209(5)
2.316(5)
2.273(5)
2.333(5)
2.117(6)
P(4)–P(6)
P(5)–P(6)
Ru–P(5)
Ru–N
2.142(6)
2.100(5)
2.353(4)
2.025(12)
2.325(4)
1.849
Ru–P(7)
Ru–Ct[a]
Bond angles
P(1)–Co–P(2)
P(1)–Co–P(3)
P(2)–Co–P(3)
P(4)–Co–P(5)
P(4)–Co–P(6)
P(5)–Co–P(6)
Co–P(5)–Ru
90.4(2)
96.1(2)
90.6(2)
54.9(2)
54.9(2)
54.2(2)
156.9(2)
P(5)–Ru–P(7)
P(5)–Ru–N
95.5(2)
94.6(3)
88.9(3)
124.8
120.2
124.3
P(7)–Ru–N
N–Ru–Ct[a]
P(5)–Ru–Ct[a]
P(7)–Ru–Ct[a]
P
M and PQ that are not coordinated to ruthenium. Such an
[a] Distance and angles formed by the centroid (Ct) of the Cp ring.
The Ru–C(Cp) distances are in the range 2.195–2.224 Å.
assignment is strongly supported by the analogous shifts
observed in the low-temperature 31P NMR spectra of the
The ruthenium atom forms a slightly longer bond to the monoadducts of [(triphos)M(η3-P3)] with metal carbonyl
P3 phosphorus atom than to the phosphane donor atom fragments.[34] It is worth noting that while the resonance of
(Table 1). These two P atoms and the CH3CN nitrogen the end-on Ru-coordinated PF atom undergoes a low-field
atom substantially span a face of an octahedron around the shift with respect to that observed for the parent [(triphos)-
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Adducts of Cyclotriphosphorus Complexes with Cyclopentadienyl Ruthenium Fragments
Table 2. 31P{1H} NMR spectroscopic data at room temperature for the “naked” P atoms of the compounds 6–15.
FULL PAPER
Compound[a]
Chemical shift, δ [ppm]
Coupling constant, J [Hz]
1
PF
PM or PQ
PQ or PM
1J(PF-PM) = J(PF-PQ)
1J(PM-PQ)
6
–175.7 (tbr)
–164.6 (tbr)
–187.9 (tbr)
–164.4 (tm)
–159.7 (tm)
–173.2 (tm)
–179.1 (tm)
–180.0 (tm)
–164.7 (tbr)
–151.5 (tbr)
–290.8 (ddbr)
–291.8 (ddbr)
–283.6 (ddbr)
–284.9 (ddm)
–288.7 (ddm)
–278.5 (ddm)
–269.9 (ddm)
–267.5 (ddm)
–259.1 (ddbr)
–276.7 (dbr)
–301.5 (ddbr)
–306.8 (ddbr)
–296.0 (ddbr)
–297.8 (ddm)
–303.6 (ddm)
–293.7 (ddm)
–274.4 (ddm)
–274.9 (ddm)
–270.9 (ddbr)
–276.7 (dbr)
320.0
320.0
321.0
337.0
338.0
335.0
340.0
330.0
303.0
320.0
264.0
256.0
260.0
265.0
257.0
258.0
256.0
259.0
252.0
0
7
8
9
10
11
12
13
14
15
[a] The NMR spectra were recorded in CD2Cl2 with a Varian Gemini g300bb spectrometer. Key: d = doublet, t = triplet, m = multiplet,
br = broad. The cyclo-P3 in the parent compounds [(triphos)M(P3)] yields a broad singlet (δ = –276.2 ppm) for M = Co (1) and a doubled
1
2
quartet [δ = –261.0, J(P–Rh) 13, J(P–Ptriphos) 12 Hz] for M = Rh (2).
M(η3-P3)] compound, the PM and PQ resonances move high
field, suggesting an increase of local electron density upon
coordination of the ruthenium moiety to the cobalt or rho-
dium cyclo-P3 starting material. The inequivalence of PM
and PQ, that is observed for all of the complexes irrespective
of the phosphane substituent, may be ascribed to the chiral-
ity of the [CpRu(CH3CN)(PR3)]+ fragment, although dif-
ferent environments of the two P atoms are likely to result
also from the effects of steric repulsions between the phenyl
ends of the {(triphos)M} moiety and the ruthenium frag-
1
ment. The J coupling constants between PF, PM, and PQ
lie in the range spanned by other end-on adducts of cyclo-
P3.[34] Both the triphos and “naked” P atom signals of the
cobalt derivatives 6–8 are broadened by the cobalt quadru-
1
pole, so that only the largest J coupling constants between
the unsusbstituted P atoms may be detected. The rhodium
complexes 9–11 exhibit broad signals for the triphos P
atoms, but sharp patterns for the “naked” phosporus nuclei.
Such data point to the occurrence at room temperature of
a dynamic process, on the NMR time scale, that involves
motion of the triphos ligand with respect to a fixed frame
formed by the “naked P” atoms. On the other hand, no
dynamic process involving the scrambling motion of the
Ru-metal moiety over the P3 cyclic system is observed at
room temperature for 6–11, irrespective of large differences
in the steric requirements of the PR3 phosphanes employed.
Figure 2. Sections of the 31P{1H} NMR spectra of 11 (CD2Cl2,
161.95 MHz). Top, experimental spectrum at 294 K; middle, exper-
imental spectrum at 233 K; bottom, simulated spectrum at 233 K.
The resonances due to the PCy3 phosphorus are omitted for clarity.
This is in contrast with the behaviour of the metal carbon- centred at 18.45, 16.75 and 10.18 ppm, with coupling con-
yls previously investigated,[34] which exhibited dynamic be- stants that range from 29.5 to 130.0 Hz (data obtained by
haviour at room temperature, and this suggests that such computer simulation) (Table 3). The 31P{1H} EXSY spectra
differences may be influenced by electronic factors, rather recorded at 294 and 248 K are reported in Figure 3. Indeed,
than by steric ones. The decomposition of the complexes two distinct sets of exchange peaks are observed, showing
upon warming their solutions prevented a through investi- that 11 attains an overall slow motional regime in the above
gation of possible dynamic processes involving the Ru-me- temperature range.[39] A set of exchange peaks is detected
tal moiety and the P3 cyclic system at higher temperatures. at temperatures higher than 260 K, and is relative to the
However, the dynamic behaviour of 11 has been carefully high-field signals due to P3 (Figure 3, top); the other set,
investigated at various temperatures by means of 1H, that can be observed below the coalescence point, connects
31P{1H} and 2D 31P{1H} EXSY spectroscopic analyses. the resonances of the triphos phosphorus atoms (Figure 3,
Sections of selected variable-temperature 31P{1H} spectra bottom).
are shown in Figure 2.
This exchange pattern is consistent with the existence of
The rate of the exchange of triphos donor atoms is low- two distinct dynamic processes that have different activation
ered on cooling the solution. In particular, at 233 K, the energies; the energy for the process for the P3 exchange is
triphos phosphorus atoms exhibit separated multiplets higher than that for the other one. Such dynamic behaviour
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P. Barbaro, M. Di Vaira, M. Peruzzini, S. Seniori Costantini, P. Stoppioni
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Table 3. 31P{1H} NMR spectroscopic data of compound 11[a]
.
Nucleus
δ [ppm]
Coupling constants JPP [Hz]
JPRh [Hz]
PB
PC
PF
PM
PQ
PCy3
PA
PB
PC
PF
PM
PQ
PCy3
10.18
16.75
18.45
–172.11
–282.16
–300.78
44.46
33.2
29.5
29.5
130.0
0.0
0.0
0.0
31.0
0.0
0.0
0.0
29.5
343.8
257.2
0.0
0.0
0.0
42.7
0.0
0.0
130.2
134.3
138.5
43.0
32.2
30.5
0.0
336.3
[a] In CD2Cl2, 161.95 MHz, 233 K. Data by computer simulation.
may be accounted for by referring to two types of motion:
(i) rotation of the P3 unit with respect to the other parts of
the structure (this motion, shown in Scheme 3 (i), involves
scrambling of the Ru moiety over the cyclic system and
yields the exchange peaks in the 294 K spectrum in Fig-
ure 3); and (ii) relative rotation of the {(triphos)M} moiety
and the rest of the structure [Scheme 3 (ii)] that accounts
for the exchange peaks in the EXSY spectrum at 248 K in
Figure 3. The two processes are simultaneous and partly
related, which makes it impossible, in view of the complex
eight-nuclei spin system, to perform any reliable analysis
addressing the thermodynamics of each exchange process.
The reactivity of the rhodium derivatives 9–11 has been
further investigated, as the fine structure exhibited by the
resonances of the “naked” atoms in the 31P NMR spectra
may provide more information on the solution behaviour
of these dimetallic derivatives. Treatment of 9 and 11 in
CH2Cl2 with a stoichiometric amount of PMe3 yields the
complexes [{(triphos)Rh}(μ,η3:1-P3){CpRu(PMe3)(PR3)}]6
[R = Ph (12), Cy (13)] (Scheme 2), which form through
replacement of CH3CN by PMe3 in the ruthenium coordi-
nation sphere. When twice as large an amount of PMe3 is
used, [(triphos)Rh(η3-P3)] (2) and [CpRu(PMe3)2(PR3)]PF6
(R = Ph, Cy) are formed, which suggests an intrinsic weak-
ness of the cyclo-P3 coordination to the [CpRu(L)(LЈ)] unit.
The 31P NMR spectra of 12 and 13 (see the Experimental
Section and Table 2) exhibit resonances for triphos, PR3,
PF, PM, and PQ with similar features to those observed for
9 and 11, besides the expected additional resonance for the
PMe3 phosphorus atom that occurs at about 2 ppm as a
pseudo triplet; such multiplicity is due to fortuitous coinci-
dence of the coupling constant to both PR3 (R = Ph, Cy)
and PF. Interestingly, the triphos resonances, which in the
parent compounds 9 and 11 appear as a broad signal, occur
as a doublet of narrower multiplets, such that the
Figure 3. 31P{1H} EXSY spectra of 11 (CD2Cl2, 161.95 MHz, τm
0.1 s). Top, spectrum at 294 K; bottom, spectrum at 248 K.
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Adducts of Cyclotriphosphorus Complexes with Cyclopentadienyl Ruthenium Fragments
FULL PAPER
Scheme 3.
1J(Ptriphos–Rh) is observed, see Experimental Section. Such at different temperatures by 31P{1H} and 2D 31P{1H}
a result points to a higher barrier for the type of motion EXSY spectroscopic data. The 31P{1H} spectra show that
shown in Scheme 3 (ii) for 12 and 13 than for 9 and 11. This the rates of exchange decrease on cooling, but even at the
in turn may be attributed to the increased steric demand of lowest reached temperature (230 K), the limiting form is not
the ruthenium fragment after replacement of the acetoni- attained. The 31P{1H} EXSY spectra at 294 K and 248 K
trile ligand by trimethylphosphane.
do not show cross peaks connecting either the triphos or
In the absence of acetonitrile, CH2Cl2 solutions 9 and 10 the P3 phosphorus atoms. These data seem to indicate that
are not stable, but slowly transform to compounds with the the dynamic processes occur with lower barriers than for 9
general formula [(triphos)Rh(P3){CpRu(PR3)}]PF6 [R = Ph and 10. Such a finding is consistent with the suggested ge-
(14) and Me (15)], by releasing the coordinated CH3CN ometry in solution; in fact, the ruthenium fragment, on in-
molecule (Scheme 2). Complexes 14 and 15 have been iso- teracting with PM and PQ, is expected to move slightly to-
lated as brown microcrystals but, in spite of repeated ward the centre of the P3 unit, thereby releasing some steric
attempts, suitable crystals for X-ray investigations have not repulsions within the cation, which are present in 9 and 10.
been obtained, so their solution structure is proposed on
the basis of 31P NMR spectroscopic data. The 31P NMR
spectra at room temperature of 14 and 15 (see Experimental
Experimental Section
Section and Table 2) exhibit resonances for triphos, PR3,
All reactions and manipulations were performed under dry oxygen-
and PF with similar shifts to those observed for 9 and 10; free argon. The solvents were purified according to standard pro-
cedures.[40] The 1H and 31P{1H} NMR spectra at room temperature
were measured on a Varian Gemini g300bb spectrometer, equipped
the triphos and PR3 signals are broad; those assigned to
P
M and PQ, on the other hand, appear at significantly lower
with a variable-temperature unit, operating at 300 MHz (1H) and
121.46 MHz (31P). The variable-temperature and EXSY experi-
ments were carried out on a Bruker Avance DRX-400 spectrometer
equipped with a variable-temperature control unit accurate to
0.1 °C and operating at 161.95 and 400.13 MHz. Chemical shifts
are relative to tetramethylsilane (1H) and to H3PO4 85 % (31P) as
external standards at δ = 0.00 ppm, with downfield values taken
as positive; coupling constants are in Hertz. J(P–P) and J(P–Rh)
field than in the parent compounds; the PF, PM and PQ
signals still appear as triplets and doublet of doublets,
respectively, but their components are broad and only the
large 1J(P–P) coupling constants may be detected. Such
data suggest that the dimetal cations in 9 and 10 have
undergone minor modifications on the loss of the acetoni-
trile molecule to yield 14 and 15, and that the 14e
{CpRu(PR3)} fragment interacts with the PM and PQ phos- coupling constants of 11 at low temperature were obtained by com-
puter simulation using the gNMR program.[41] 2D NMR spectra
phorus atoms of the P3 unit. Furthermore, the data are con-
were recorded on degassed nonspinning samples using pulse se-
sistent with the rotational motion of the {(triphos)Rh} moi-
quences suitable for phase-sensitive representations with TPPI. The
ety and, on account of the broad resonances exhibited by
the PR3, PF, PM, and PQ atoms, they point to a further
process involving the CpRu(PR3)P3 side of the dimetal cat-
2D 31P{1H} EXSY spectra were recorded using a modified
1
NOESY sequence with H decoupling during acquisition: 400 in-
crements of size 3 K (with 400 scans each) covering the full range
ion. A type of motion that might account for the latter as-
in both dimensions were collected with a relaxation delay of 0.25 s
pects would be that of the ruthenium fragment, tightly
bound to a P3 phosphorus atom, that shifts between the
positions of the other two, and therefore yields a dynamic
and mixing times of 50, 100 and 500 ms.[42,43] Analytical data for
carbon, hydrogen, nitrogen, and phosphorus were obtained from
the Microanalytical Laboratory of the Department of Chemistry
μ,η3:1,1Ј-P3 unit. The behaviour of 14 has been investigated of the University of Firenze. The complexes [(triphos)M(η3-P3)] (M
Eur. J. Inorg. Chem. 2005, 1360–1368
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P. Barbaro, M. Di Vaira, M. Peruzzini, S. Seniori Costantini, P. Stoppioni
FULL PAPER
= Co (1), Rh (2) and [CpRu(CH3CN)2(PR3)]PF6 [PR3 = PPh3 (3),
PMe3 (4) and PCy3 (5)] were synthesized according to literature
(CD2Cl2, 298 K): δ = 4.23 (s, C5H5, 5 H), 2.40–1.4 (br. m, C6H11,
CH2P, CH3CN, CH3C) ppm. 31P{1H} NMR (CD2Cl2, 298 K): δ =
44.4 [d, PCy3, J(PCy3–PF) 44.5, 1P], 16.0 (br., Ptriphos, 3P) ppm.
1
2
methods.[19,20,38] The H NMR spectroscopic data of the dinuclear
adducts 6–15 and the 31P{1H} resonances of the phosphane ligands
(triphos and PR3) are reported in this section. The uninformative
1H signals of the aromatic protons of triphos and of the PPh3 deriv-
atives, occurring in the expected region (7.6–6.9 ppm), are not re-
ported. The labelling used for the different phosphorus nuclei is
[{(triphos)Rh}(μ,η3:1-P3){CpRu(PMe3)(PPh3)}]PF6 (12): To an
orange solution of [{(triphos)Rh}(μ,η3:1-P3){CpRu(CH3CN)-
(PPh3)}]PF6 (9) [143 mg, 0.10 mmol] in CH2Cl2 (20 mL) was added
at room temperature whilst stirring an equimolar amount of neat
PMe3. The resulting solution was stirred for 2 h; toluene (15 mL)
was then slowly added; reddish-orange crystals were obtained by
slowly evaporating the resulting solution at room temperature.
Yield: 200 mg (80 %). C67H68F6P9RhRu (1469.9): calcd. C 54.7, H
–
defined in Scheme 2. The PF6 anion yields a septet centred at
–143.2 [1J(P–F) 712 Hz] in all the compounds.
Syntheses
1
4.7 %; found C 54.5, H 4.6 %. H NMR (CD2Cl2, 298 K): δ = 4.34
[{(triphos)Co}(μ,η3:1-P3){CpRu(CH3CN)(PPh3)}]PF6 (6): To a yel-
lowish orange solution of [(triphos)Co(η3-P3)] (1) [132 mg,
0.17 mmol] in CH2Cl2 (40 mL) was added at room temperature
whilst stirring one equivalent of [CpRu(CH3CN)2(PPh3)]PF6 (3) in
CH2Cl2 (10 mL). The resulting solution was stirred for 3 h at room
temperature, and during this time the colour changed to brown-red.
Acetonitrile (1 mL) and toluene (10 mL) were then slowly added to
yield reddish brown crystals by slowly evaporating the resulting
solution at room temperature. Yield: 201 mg (85 %).
C66H62CoF6NP8Ru (1390.9): calcd. C 57.0, H 4.5, N 1.0 %; found
C 57.1, H 4.8, N 0.9 %. 1H NMR (CD2Cl2, 298 K): δ = 4.14 (s,
C5H5, 5 H), 2.40 (br., CH2P, 6 H), 2.20 (br. s, CH3CN, 3 H), 1.37
(br. s, CH3C, 3 H) ppm. 31P{1H} NMR (CD2Cl2, 298 K): δ = 50.2
(s, C5H5, 5 H), 2.41 (br., CH2P, 6 H), 1.52 (s, CH3C, 3 H), 1.31 [d,
2
CH3P, J(H–P) = 9.3, 9 H] ppm. 31P{1H} NMR (CD2Cl2, 298 K):
δ = 50.2 [dd, PPh3, 2J(PPh3–PMe3) 41.5, 2J(PPh3–PF) 36.5, 1P],
16.5 [br. d, Ptriphos,
1J(Ptriphos–Rh) 130.5, 3P], 2.2 [t, PMe3,
2J(PMe3–PF) 42.0, 1P] ppm.
[{(triphos)Rh}(μ,η3:1-P3){CpRu(PMe3)(PCy3)}]PF6 (13): Complex
13 was prepared as described above for 12 by using 11 instead of
9. Yield: 202 mg (80 %). C67H86F6P9RhRu (1488.1): calcd. C 54.1,
H 5.8 %; found C 54.2, H 5.9 %. 1H NMR (CD2Cl2, 298 K): δ =
4.32 (s, C5H5, 5 H), 2.40–1.30 (br. m, C6H11, CH2P, CH3C, 42 H),
1.25 [d, CH3P, 2J(H–P) 8.7, 9 H] ppm. 31P{1H} NMR (CD2Cl2,
298 K): δ = 46.0 [t, PCy3, 2J(PCy3–PMe3) = 2J(PCy3–PF) 39.0, 1P],
15.0 [br. d, Ptriphos,
1J(Ptriphos–Rh) 120.0, 3P], 2.1 [t, PMe3,
2
[d, PPh3, J(PPh3–PF) 36.5, 1P], 34.2 (br., Ptriphos, 3P) ppm.
2J(PMe3–PF) 40.0, 1P] ppm.
The compounds [{(triphos)M}(μ,η3:1-P3){CpRu(CH3CN)(PR3)}]
PF6 [M = Co; R = Me (7), Cy (8); M = Rh; R = Ph (9), Me (10),
Cy (11)] were prepared by the same procedure as for 6 by adding
the equimolar amount of [CpRu(CH3CN)2(PR3)]PF6 [R = Ph (3),
Me (4), Cy (5)] to a CH2Cl2 solution of [(triphos)M(η3-P3)] [M =
Co (1), Rh(2)].
[{(triphos)Rh}(μ,η3:1,1Ј-P3){CpRu(PPh3)}]PF6 (14): [(triphos)Rh(η3-
P3)] (2) and [CpRu(CH3CN)2(PPh3)]PF6 (3) were reacted as de-
scribed for 9 avoiding the subsequent addition of acetonitrile.
Brown microcrystals were obtained by adding only toluene, and
slowly concentrating the resulting solution. Yield: 154 mg (65 %).
C64H59F6P8RhRu (1393.8): calcd. C 55.1, H 4.3, P 17.8 %; found
C 55.2, H 4.4, P 17.6 %. 1H NMR (CD2Cl2, 298 K): δ = 4.02 (s,
C5H5, 5 H), 2.37 (br., CH2P, 6 H), 1.53 (s, CH3C, 3 H) ppm.
31P{1H} NMR (CD2Cl2, 298 K): δ = 48.4 (br. s, PPh3, 1P), 15.5
[{(triphos)Co}(μ,η3:1-P3){CpRu(CH3CN)(PMe3)}]PF6 (7): Yield:
123 mg (60 %). C51H56CoF6NP8Ru (1204.7): calcd. C 50.8, H 4.7,
N 1.2 %; found C 50.7, H 4.8, N 1.0 %. 1H NMR (CD2Cl2, 298 K):
δ = 4.27 (s, C5H5, 5 H), 2.37 (br., CH2P, 6 H), 2.17 (s, CH3CN, 3
H), 1.65 (d, CH3P, 2J(H-P) 9.6, 9 H), 1.39 (s, CH3C, 3 H) ppm.
31P{1H} NMR (CD2Cl2, 298 K): δ = 32.7 (br., Ptriphos, 3P), 10.0 [d,
[dq, Ptriphos
ppm.
,
1J(Ptriphos–Rh) 132.0, 2J(Ptriphos–Pcyclo-P3) 21.0, 3P]
[{(triphos)Rh}(μ,η3:1,1Ј-P3){CpRu(PMe3)}]PF6 (15): Brown micro-
crystals of 15 were obtained as described above for 14 by reacting
[(triphos)Rh(η3-P3)] (2) and [CpRu(CH3CN)2(PMe3)]PF6 (4) in a
1:1 ratio in CH2Cl2. Yield: 123 mg (60 %). C49H53F6P8RhRu
(1207.6): calcd. C 48.7, H 4.4, P 20.5 %; found C 48.9, H 4.4, P
2
PMe3, J(PMe3–PF) 46.0, 1P] ppm.
[{(triphos)Co}(μ,η3:1-P3){CpRu(CH3CN)(PCy3)}]PF6 (8): Yield:
204 mg (85 %). C66H80CoF6NP8Ru (1409.1): calcd. C 56.2, H 5.7,
N 1.0 %; found C 56.1, H 5.8, N 0.8 %. 1H NMR (CD2Cl2, 298 K):
δ = 4.27 (s, C5H5, 5 H), 2.40–1.40 (br. m, C6H11, CH2P, CH3CN,
CH3C, 45 H) ppm. 31P{1H} NMR (CD2Cl2, 298 K): δ = 42.2 [d,
1
20.2 %. H NMR (CD2Cl2, 298 K): δ = 4.15 (s, C5H5, 5 H), 2.37
(br., CH2P, 6 H), 1.53 (s, CH3C, 3 H), 1.50 [d, CH3P, 2J(H–P)
2
PCy3, J(PCy3–PF) 39.0, 1P], 32.9 (br., Ptriphos, 3P) ppm.
9.3] ppm. 31P{1H} NMR (CD2Cl2, 298 K): δ = 16.2 [dm, Ptriphos
,
[{(triphos)Rh}(μ,η3:1-P3){CpRu(CH3CN)(PPh3)}]PF6 (9): Yield:
207 mg (85 %). C66H62F6NP8RhRu (1434.9): calcd. C 55.2, H 4.3,
N 1.0 %; found C 55.1, H 4.5, N 0.9 %. 1H NMR (CD2Cl2, 298 K):
δ = 4.20 (s, C5H5, 5 H), 2.47 (br., CH2P, 6 H), 2.20 (s, CH3CN, 3
H), 1.31 (s, CH3C, 3 H) ppm. 31P{1H} NMR (CD2Cl2, 298 K): δ
1J(Ptriphos–Rh) 127.0, 3P], 8.0 (m, PMe3, 1P) ppm.
Crystal Structure Determination
Obtaining crystals suitable for X-ray analyses on these compounds
proved to be difficult; a data set could only be collected with a
very small crystal of 6, grown from a diluted CH2Cl2/CH3CN/C7H8
solution, which gave relatively low-angle reflections. Data were col-
lected at room temperature with a Bruker CCD diffractometer,
equipped with Göbel mirrors and mounted on a rotating-anode
generator, using Cu-Kα radiation (λ = 1.5418 Å). Cell constants
were obtained by least-squares refinement of the setting angles of
791 reflections in the range 7° Ͻ 2θ Ͻ 55°. Crystallographic data
and details on the structure determination and refinement pro-
cedure are summarised in Table 4. Although limited absorption ef-
fects were expected, in view of the small size of the crystal, a correc-
2
= 51.0 [d, PPh3, J(PPh3–PF) 44.5, 1P], 16.9 (br., Ptriphos, 3P) ppm.
[{(triphos)Rh}(μ,η3:1-P3){CpRu(CH3CN)(PMe3)}]PF6 (10): Yield:
138 mg (65 %). C51H56F6NP8RhRu (1248.7): calcd. C 49.0, H 4.5,
1
N 1.1; found C 49.3, H 4.6, N 1.0 %. H NMR (CD2Cl2, 298 K):
δ = 4.42 (s, C5H5, 5 H), 2.48 (br., CH2P, 6 H), 2.21 (s, CH3CN, 3
2
H), 1.67 (d, CH3P, J(H-P) = 9.6, 9 H), 1.52 (s, CH3C, 3 H) ppm.
31P{1H} NMR (CD2Cl2, 298 K): δ = 16.8 (br., Ptriphos, 3P), 9.8 [d,
2
PMe3, J(PMe3–PF) 49.5, 1P] ppm.
[{(triphos)Rh}(μ,η3:1-P3){CpRu(CH3CN)(PCy3)}]PF6 (11): Yield:
210 mg (85 %). C66H80F6NP8RhRu (1453.0): calcd. C 54.5, H 5.5, tion for absorption was applied with SADABS,[44] in an attempt to
1
N 1.0, P 17.0 %; found C 54.3, H 5.7, N 0.8, P 16.8 %. H NMR
reduce the effects of absorption by the glass fibre, which caused
1366
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Adducts of Cyclotriphosphorus Complexes with Cyclopentadienyl Ruthenium Fragments
FULL PAPER
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[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
eq
eq
Table 4. Crystal data and structure refinement parameters for 6.
Empirical formula
Formula weight
Crystal system
Space group
a [Å]
C80H78CoF6NP8Ru
1575.19
orthorhombic
Pcab (no. 61)
22.138(4)
b [Å]
22.955(5)
c [Å]
30.038(7)
15265(6)
V [Å3]
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Z
8
Dcalcd. [g cm–3]
1.371
5.364
μ [mm–1]
[19]
[20]
[21]
[22]
[23]
[24]
[25]
[26]
[27]
[28]
[29]
[30]
Transmission factors range
Crystal size [mm]
F(000)
θ range [°]
Index ranges
0.549–1.000
0.05 × 0.08 × 0.40
6480
2.94–37.56
–17 Յ h Յ 17,
–18 Յ k Յ 17,
–23 Յ l Յ 23
33678
Reflections collected
M. Di Vaira, M. Peruzzini, P. Stoppioni, J. Chem. Soc. Dalton
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Independent reflections
Independent observed reflections
Restraints/Parameters
3873 [Rint = 0.322]
1507 [I Ͼ 2σ(I)]
313/572
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Final R indices [I Ͼ 2σ(I)]
R indices (all data)
R1 = 0.056, wR2 = 0.071
R1 = 0.199, wR2 = 0.093
0.806
Goodness of fit on F2 (all data)
Largest diff. peak and hole [e·Å–3]
0.316 to –0.250
CCDC-244899 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
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We acknowledge financial support by the Ministero dellЈUniversità
e della Ricerca Scientifica e Tecnologica (Rome) and by the Euro-
pean Commission through the program INTAS (00–00018).
Thanks are also expressed to THERMPHOS International, Vliss-
ingen, NL for supporting this research.
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Received: October 8, 2004
1368
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Eur. J. Inorg. Chem. 2005, 1360–1368