Ruthenium(II) and ruthenium(IV) complexes containing hemilabile heterodifunctional iminophosphorane-phosphine ligands Ph2PCH2P(=NR)Ph2

Article abstract of DOI:10.1039/b110442j

The dimeric complex [{Ru(η⁶-p-cymene)(μ-Cl)Cl}₂] reacts with iminophosphorane-phosphine ligands Ph₂PCH₂-P(=NR)Ph₂ (R = SiMe₃ 1, p-C₆F₄CN 2, p-C₅F₄

Full text of DOI:10.1039/b110442j

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Ruthenium(II) and ruthenium(IV) complexes containing hemilabile
heterodifunctional iminophosphorane-phosphine ligands
Ph PCH P(᎐NR)Ph †
᎐
2
2
2
Victorio Cadierno,a Josefina Díez,a Sergio E. García-Garrido,a Santiago García-Grandab
and José Gimeno*a
a Departamento de Química Orgánica e Inorgánica, Instituto Universitario de Química
Organometálica ‘Enrique Moles’ (Unidad Asociada al C.S.I.C.), Universidad de Oviedo,
E-33071 Oviedo, Spain. E-mail: jgh@sauron.quimica.uniovi.es.
b Departamento de Química Física y Analítica, Universidad de Oviedo, E-33071 Oviedo, Spain
Received 14th November 2001, Accepted 17th January 2002
First published as an Advance Article on the web 1st March 2002
The dimeric complex [{Ru(η6-p-cymene)(µ-Cl)Cl}2] reacts with iminophosphorane-phosphine ligands Ph2PCH2-
P(᎐NR)Ph (R = SiMe 1, p-C F CN 2, p-C F N 3), in dichloromethane at room temperature, to afford the neutral
᎐
2
3
6
4
5
4
derivatives [Ru(η6-p-cymene)Cl {κ1-P-Ph PCH P(᎐NR)Ph }] (R = SiMe 4, p-C F CN 5, p-C F N 6). Treatment of
᎐
2
2
2
2
3
6
4
5
4
4–6 with NaPF in methanol allows the preparation of cationic species [Ru(η6-p-cymene)Cl{κ2-P, N -Ph PCH P(᎐NR)-
᎐
6
2
2
Ph2}][PF6] (R = H 7, p-C6F4CN 8, p-C5F4N 9). While complexes 8 and 9 react with anionic ligands yielding neutral
derivatives [Ru(η6-p-cymene)X {κ1-P-Ph PCH P(᎐NR)Ph }] (R = p-C F CN, X = Br 10a, I 10b, N 10c, CN 10d,
᎐
2
2
2
2
6
4
3
NCO 10e; R = p-C5F4N, X = Br 11a, I 11b, N3 11c, CN 11d, NCO 11e), cationic species [Ru(η6-p-cymene)X{κ2-P, N -
Ph PCH P(᎐NH)Ph }][PF ] (X = Br 12a, I 12b, N 12c, CN 12d, NCO 12e) are exclusively formed starting from 7.
᎐
2
2
2
6
3
Complexes 8 and 9 also react with neutral ligands such as phosphines, pyridine, acetonitrile or isocyanides
affording compounds [Ru(η6-p-cymene)Cl(PR ){κ1-P-Ph PCH P(᎐NR)Ph }][PF ] (R = p-C F CN, PR = PMe
᎐
3
2
2
2
6
6
4
3
3
13a, PMe2Ph 13b, PMePh2 13c, PPh3 13d; R = p-C5F4N, PR3 = PMe3 14a, PMe2Ph 14b, PMePh2 14c, PPh3 14d),
[Ru(η6-p-cymene)Cl(py){κ1-P-Ph PCH P(᎐NR)Ph }][PF ] (R = p-C F CN 15; R = p-C F N 16), [Ru(η6-p-cymene)Cl-
᎐
2
2
2
6
6
4
5
4
1
6
᎐
(N᎐CMe){κ -P-Ph PCH P(᎐NR)Ph }][PF ] (R = p-C F CN 17; R = p-C F N 18) and [Ru(η -p-cymene)Cl(CNRЈ)-
᎐
᎐
2
2
2
6
6
4
5
4
{κ1-P-Ph PCH P(᎐NR)Ph }][PF ] (R = p-C F CN, RЈ = Cy 19a, 2,6-C H Me 19b; R = p-C F N, RЈ = Cy 20a,
᎐
2
2
2
6
6
4
6
3
2
5
4
2,6-C H Me 20b), respectively. The synthesis of complexes [Ru(η3:η3-C H )Cl {κ1-P-Ph PCH P(᎐NR)Ph }]
᎐
6
3
2
10 16
2
2
2
2
(R = SiMe 21, p-C F CN 22, p-C F N 23) and [Ru(η3:η3-C H )Cl{κ -P, N -Ph PCH P(᎐NH)Ph }][BF ] 24
᎐
3
6
4
5
4
10 16
2
2
2
2
4
starting from the bis(allyl)-ruthenium() dimer [{Ru(η3:η3-C10H16)(µ-Cl)Cl}2] and ligands 1–3 is also reported.
The coordination chemistry of heterodifunctional ligands,
bearing both “hard” (e.g. N, O) and “soft” (e.g. P) donor atoms,
is an area of considerable current interest since they show hemi-
labile1 properties providing potential applications in catalysis.2
Typical examples are the well-known diphosphine-monoxides,
complexes containing iminophosphorane-phosphine ligands
(see Chart 1). In addition, the lability of the coordinated –Ph P᎐
᎐
2
NR moiety in some of these complexes has been investigated.
e.g. R P–(CH ) –P(᎐O)R , which, since the pioneering works by
᎐
2
2
n
2
Grim and co-workers,3 have been widely studied and success-
fully applied in a large number of catalytic transformations.4 In
contrast, much less attention has been devoted to the chemistry
of the closely related iminophosphorane-phosphine ligands
R P–(CH ) –P(᎐NRЈ)R ,5 although they are readily accessible
᎐
2
2
n
2
from diphosphines via selective monoimination with a large
variety of azides (Staudinger reaction).6,7 Most of the reported
complexes belong to the series of the functionalized dppm
Chart 1 Iminophosphorane-phosphine ligands used in this paper.
ligands Ph P–CH –P(᎐NR)Ph , i.e. Ni,8 Pd,6c,6f,9 Mo,10 W, 10a
᎐
2
2
2
Co,8a Rh,8a,9d,10a,11 Ir,10a,11d Ti,6b,12 and Re13 species, in which the
iminophosphorane-phosphines are acting as chelate ligands
through the P() and N atoms. Although some of them show
catalytic activity in hydrogenation of olefins,11c and carbonyl-
ation of methanol,8a as far as we are aware, no studies on their
hemilabile properties have been reported to date.
Results and discussion
Synthesis of ruthenium(II) complexes [Ru(ꢀ6-p-cymene)Cl2{ꢁ1-P-
Ph PCH P(᎐NR)Ph }] (R ؍ SiMe 4, p-C F CN 5, p-C F N 6)
᎐
2
2
2
3
6
4
5
4
and [Ru(ꢀ6-p-cymene)Cl{ꢁ2-P,N-Ph PCH P(᎐NR)Ph }][PF ]
᎐
2
2
2
6
(R ؍ H 7, p-C6F4CN 8, p-C5F4N 9)
The ability of dimers [{Ru(η6-arene)(µ-Cl)Cl}2] to form mono-
and dinuclear ruthenium() complexes of general formula [Ru-
(η6-arene)Cl2L] and [{Ru(η6-arene)Cl2}2(µ-L)] is well-known.15
As expected, we have found that the reaction of [{Ru(η6-
Following our interest in the chemistry of ruthenium com-
plexes containing hybrid P/N-donor ligands,14 here we describe
the preparation of the first ruthenium() and ruthenium()
p-cymene)(µ-Cl)Cl}2]16 with
a two-fold excess of imino-
† Electronic supplementary information (ESI) available: analytical and
spectroscopic data. See http://www.rsc.org/suppdata/dt/b1/b110442j/
phosphorane-phosphines Ph PCH P(᎐NR)Ph (R = SiMe 1,
᎐
2
2
2
3
DOI: 10.1039/b110442j
J. Chem. Soc., Dalton Trans., 2002, 1465–1472
This journal is © The Royal Society of Chemistry 2002
1465

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Scheme 1 Coordination of iminophosphorane-phosphine ligands on a (η6-arene)-ruthenium() moiety: (a) Molar ratio complex/NaPF6 : 4 (1 : 1),
5 (1 : 12), 6 (1 : 12). (b) R = p-C6F4CN, p-C5F4N.
p-C6F4CN 2, p-C5F4N 3),6b,10a in dichloromethane at room
temperature, affords the mononuclear compounds [Ru(η6-p-
yields (Scheme 1). Complexes 7–9 can be also prepared in sim-
ilar yields starting from [{Ru(η6-p-cymene)(µ-Cl)Cl}2] by reac-
tion with the corresponding iminophosphorane-phosphine and
NaPF6 in methanol at room temperature (Scheme 1).
cymene)Cl {κ1-P-Ph PCH P(᎐NR)Ph }] (R = SiMe 4, p-C F -
᎐
2
2
2
2
3
6
4
CN 5, p-C5F4N 6; 69–78% yield) (Scheme 1). No dinuclear
bridged products were detected even when the reactions were
Analytical and spectroscopic data (IR and 31P-{1H}, 1H, 19
F
carried out with only one equivalent of Ph PCH P(᎐NR)Ph
and 13C-{1H}) for 7–9 are in agreement with the formation of a
chelate ring (see Tables S5 and S6 provided as Supplementary
Information†). This can be assessed spectroscopically by: (i) a
strong downfield shift of the 31P-{1H} NMR signals with doub-
lets (2J(PP) = 15.5–22.0) in the ranges δP 48.3–50.0 (Ph2P) and
᎐
2
2
2
obtaining instead equimolar mixtures of 4–6 and the precursor
complex [{Ru(η6-p-cymene)(µ-Cl)Cl}2].
The unequivocal characterization of complexes 4–6 was
achieved by means of standard spectroscopic techniques (IR
and 31P-{1H}, 1H, 19F and 13C-{1H}) as well as elemental
analyses (see Tables S1–S4 provided as Supplementary Inform-
ation†). The most significant features are: (i) (31P-{1H} NMR)
Two doublet resonances (2J(PP) = 35.1–37.4) consistent with
an AX spin system in the ranges δP Ϫ5.8 to 9.2 and 21.5–
22.0 corresponding to the iminophosphorane and phosphine
moieties, respectively. (ii) (1H NMR) A virtual triplet signal
(2J(HP) = 8.8–10.3 Hz) at 3.75–4.28 ppm for the methylenic
PCH2P protons. (iii) (13C-{1H} NMR) A doublet of doublets
resonance (J(CP) = 55.3–76.3 (P()) and 18.0–25.0 (P())) for
the PCH2P carbon at ca. 22 ppm. And, (iv) (19F NMR) the
presence for complexes 5 and 6 of two multiplets (AAЈBBЈ
spin system) at similar chemical shifts (see Tables S1 and S3
provided as Supplementary Information†) to those reported
for the free ligands 2 and 3.10a IR absorption bands which
appear in the range of 1000–1300 cmϪ1 can be tentatively
54.5–55.3 (Ph P᎐N), as well as a slight deshielding (ca. ∆δ
=
᎐
2
C
7 ppm) of the methylenic PCH2P carbon resonances (dd,
J(CP) = 77.3–84.2 (P()) and 19.1–25.7 (P())), compared to
the starting materials 4–6. (ii) The chemical inequivalence of
the methylenic PCH2P protons which appear as one or two
unresolved multiplets at 3.20–4.04 ppm. And, (iii) the inequiv-
alence of the methyl and CH carbons and protons of the
p-cymene group, as a consequence of the chirality of the
ruthenium atom. A similar effect is also observed in the 19F
NMR spectra of complexes 8 and 9 which show, in addition to
Ϫ
the expected PF6 doublet, four multiplets for the p-C6F4CN
and p-C5F4N groups (see the Supplementary Information†).
We also note that, although in the 1H NMR spectrum of com-
plex 7 the NH proton could not be detected, the presence of
such functionality was clearly evidenced by the IR spectrum
(KBr) which shows a ν(NH) absorption at 3367 cmϪ1
.
assigned to ν(P᎐N) of the iminophosphorane group, but they
᎐
Hemilabile properties of ruthenium(II) complexes [Ru(ꢀ6-p-
are in general overlapped by those of the rest of the ligands, and
consequently, the correct assignment is uncertain.
cymene)Cl{ꢁ2-P,N-Ph PCH P(᎐NR)Ph }][PF ] (R ؍ H 7,
᎐
2
2
2
6
Treatment of [Ru(η6-p-cymene)Cl {κ1-P-Ph PCH P(᎐NR)-
᎐
2
2
2
p-C6F4CN 8, p-C5F4N 9)
Ph2}] (R = SiMe3 4, p-C6F4CN 5, p-C5F4N 6) with NaPF6, in
methanol at room temperature, allows the N-coordination of
the iminophosphorane moiety to ruthenium affording cationic
Taking into account the lability of the iminophosphorane-
phosphines 2–3 in complexes 8–9 which allows the coordination
of a chloride ligand through the decoordination of the –Ph P᎐
NR moiety (Scheme 1), we believed the study of the scope
of this reactivity in the presence of other anionic and neutral
ligands to be of interest.
derivatives [Ru(η6-p-cymene)Cl{κ2-P, N -Ph PCH P(᎐NR)Ph }]-
᎐
2
᎐
2
2
2
[PF6] (R = H 7, p-C6F4CN 8, p-C5F4N 9) in 79–84% yield
(Scheme 1). Formation of complex 7 involves the desilylation
of the coordinated Ph PCH P(᎐NSiMe )Ph ligand in 4. We
᎐
2
2
3
2
note that the selective cleavage of the N–Si bond in the free
ligand with methanol has been reported to produce Ph2-
(a) Synthesis of [Ru(ꢀ6-p-cymene)X {ꢁ1-P-Ph PCH P(᎐NR)-
Ph2}] (R ؍ p-C6F4CN, X ؍ Br 10a, I 10b, N3 10c, CN 10d, NCO
᎐
2
2
2
PCH P(᎐NH)Ph and Me SiOMe.17 In contrast to the form-
᎐
2
2
3
ation of complex 7 which requires only one equiv. of NaPF6,
compounds 8 and 9 are only formed in the presence of a large
excess of NaPF6 (ca. 12 equiv.), otherwise a mixture containing
the starting materials is obtained. This seems to indicate the
existence of an equilibrium due to the presence of the chloride
anion in the reaction mixture. In fact the reversible process
occurs when 8–9 are treated with an excess of NaCl in methanol
affording the precursor complexes 5–6 in almost quantitative
10e; R ؍ p-C5F4N, X ؍ Br 11a, I 11b, N3 11c, CN 11d, NCO
11e) and [Ru(ꢀ6-p-cymene)X{ꢁ2-P,N-Ph PCH P(᎐NH)Ph }]-
᎐
2
2
2
[PF6] (X ؍ Br 12a, I 12b, N3 12c, CN 12d, NCO 12e). Com-
plexes 8 and 9 react with an excess (ca. 16 equiv.) of sodium
salts NaX (XϪ = BrϪ, IϪ, N3Ϫ, CNϪ, NCOϪ), in methanol
at room temperature, to yield neutral derivatives [Ru(η6-p-
cymene)X {κ1-P-Ph PCH P(᎐NR)Ph }] (R = p-C F CN, X =
᎐
2
2
2
2
6
4
Br 10a, I 10b, N3 10c, CN 10d, NCO 10e; R = p-C5F4N, X =
1466
J. Chem. Soc., Dalton Trans., 2002, 1465–1472

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Fig. 1 ORTEP-type view of the structure of [Ru(η6-p-cymene)(κ1-N-
NCO)2{κ1-P-Ph2PCH2P(᎐N-p-C6F4CN)Ph2}] 10e showing the crystal-
Scheme 2 Reactivity of complexes 7–9 towards anionic ligands.
᎐
lographic labeling scheme. Hydrogen atoms are omitted for clarity, and
only the ipso-carbons of the phenyl rings are shown. Thermal ellipsoids
are drawn at the 30% probability level. Selected bond lengths (Å) and
angles (Њ): Ru–C* 1.712(4); Ru–N(1) 2.075(4); Ru–N(2) 2.104(4);
Ru–P(1) 2.340(1); N(1)–C(11) 1.127(7); N(2)–C(12) 1.116(7); C(11)–
O(1) 1.199(7); C(12)–O(2) 1.216(8); P(1)–C(13) 1.842(5); C(13)–P(2)
1.828(5); P(2)–N(3) 1.569(4); N(3)–C(26) 1.333(6); C*–Ru–N(1)
129.0(2); C*–Ru–N(2) 127.4(2); C*–Ru–P(1) 129.3(2); Ru–N(1)–
C(11) 176.9(5); Ru–N(2)–C(12) 166.2(5); Ru–P(1)–C(13) 111.28(16);
Ru–P(1)–C(14) 111.64(16); Ru–P(1)–C(20) 114.13(16); N(1)–C(11)–
O(1) 178.0(8); N(2)–C(12)–O(2) 178.6(9); N(1)–Ru–N(2) 84.78(17);
N(1)–Ru–P(1) 84.27(12); N(2)–Ru–P(1) 86.60(12); P(1)–C(13)–P(2)
120.4(3); C(13)–P(2)–N(3) 117.7(2); P(2)–N(3)–C(26) 139.0(4); C(13)–
P(2)–C(33) 104.8(2); C(13)–P(2)–C(39) 106.4(2). C* = centroid of the
p-cymene ring (C(2), C(3), C(4), C(5), C(6), C(7)).
Br 11a, I 11b, N3 11c, CN 11d, NCO 11e) (69–92% yield;
Scheme 2).
NMR spectroscopic data (see Tables S1–S4 provided as
Supplementary Information†) provide structural information
on the chelate ring opening. Thus, the monodentate coordin-
ation of the iminophosphorane-phosphine ligands is assessed
in the 31P-{1H} NMR spectra by a lowfield shift in both Ph2P
(δP 15.1–39.0) and Ph P᎐N (δ 8.2–10.2) resonances with
᎐
2
P
respect to the parent compounds 8 and 9, being comparable
1
to those observed in monodentated complexes 5 and 6. H,
13C-{1H} and 19F NMR spectra are also in accord with the
proposed formulations (see Tables S1–S4 provided as Sup-
plementary Information†), in particular the methylenic PCH2P
proton and carbon resonances which appear at 3.77–4.80 (vt,
2J(HP) = 9.0–10.5) and 21.66–31.80 (dd, J(CP) = 51.1–72.7
(P()) and 12.4–25.0 (P())) ppm, respectively. Moreover, the
structure of complex 10e has been confirmed by a X-ray diffrac-
tion study. A drawing of the molecular structure is shown in
Fig. 1; selected bond distances and angles are listed in the cap-
tion. The molecule exhibits an usual pseudooctahedral three-
legged piano-stool geometry with values of the interligand
angles N(1)–Ru–N(2), N(1)–Ru–P(1) and N(2)–Ru–P(1), and
those between the centroid of the arene ring C* and the legs
typical of a pseudo-octahedron. The two cyanate ligands are
bound to ruthenium in a nearly linear fashion (Ru–N(1)–
C(11) 176.9(5)Њ, N(1)–C(11)–O(1) 178.0(8)Њ, Ru–N(2)–C(12)
166.2(5)Њ, N(2)–C(12)–O(2) 178.6(9)Њ) showing bond lengths
of Ru–N(1) 2.075(4) Å, N(1)–C(11) 1.127(7) Å, C(11)–O(1)
1.199(7) Å, Ru–N(2) 2.104(4) Å, N(2)–C(12) 1.116(7) Å
and C(12)–O(2) 1.216(8) Å. It is worth mentioning that in
transition-metal cyanato compounds a decision between N-
and O-bonding from X-ray structural analysis is not so straight-
forward because of the very similar sizes and scattering factors
for N and O.18 We decided in favor of N-bonding on the basis
of the following considerations: (i) Both N- and O-bonded
models were refined to convergence, and the former gave signifi-
cantly lower residuals (R = 0.0637 and Rw = 0.0708 as against
R = 0.0652 and Rw = 0.0723). (ii) The virtual linearity of the
Ru–N–C–O chains is more consistent with the N-bonded
model.19 The N-coordination is also enterely in accord with
both molecular orbital calculations reported by Tuan and
Hoffmann, which predict the greater stability of the M–NCO
linkage.20 Literature precedents for the O-coordination of the
cyanate ion are scarce.21 The structural parameters observed for
the uncoordinated iminophosphorane unit (P(2)–N(3) 1.569(4)
Å; C(13)–P(2)–N(3) 117.7(2)Њ, P(2)–N(3)–C(26) 139.0(4)Њ) can
In contrast to the behaviour of complexes 8 and 9, the treat-
ment of complex [Ru(η6-p-cymene)Cl{κ2-P, N -Ph2PCH2P-
(᎐NH)Ph }][PF ] 7 with anionic ligands (BrϪ, IϪ, N Ϫ, CNϪ,
᎐
2
6
3
NCOϪ) affords, under the same reaction conditions, the cat-
ionic derivatives [Ru(η6-p-cymene)X{κ2-P, N -Ph PCH P(᎐NH)-
᎐
2
2
Ph2}][PF6] (X = Br 12a, I 12b, N3 12c, CN 12d, NCO 12e;
76–92% yield) as the result of the metathesis of the chloride
ligand (Scheme 2). This result reflects the lack of lability of the
chelating ligand Ph PCH P(᎐NH)Ph in 7 as it has been also
᎐
2
2
2
observed in its reaction of synthesis (Scheme 1). Apparently,
the presence of bulky and strong electron withdrawing sub-
stituents on the iminophosphorane unit induces the lability of
the Ru–N bond. Since the analytical and spectroscopic data of
12a–e are comparable to those observed for its precursor 7 they
will not be further discussed (see Tables S5 and S6 provided as
Supplementary Information†).
(b) Synthesis of [Ru(ꢀ6-p-cymene)Cl(PR3){ꢁ1-P-Ph2PCH2P-
(᎐NR)Ph }][PF ] (R ؍ p-C F CN, L ؍ PMe 13a, PMe Ph 13b,
᎐
2
6
6
4
3
2
PMePh2 13c, PPh3 13d; R ؍ p-C5F4N, PR3 ؍ PMe3 14a,
PMe2Ph 14b, PMePh2 14c, PPh3 14d), [Ru(ꢀ6-p-cymene)Cl(py)-
{ꢁ1-P-Ph PCH P(᎐NR)Ph }][PF ] (R ؍ p-C F CN 15; R ؍
᎐
2
2
2
6
6
4
p-C5F4N 16) and [Ru(ꢀ6-p-cymene)Cl(CNRЈ){ꢁ1-P-Ph2PCH2-
P(᎐NR)Ph }][PF ] (R ؍ p-C F CN, RЈ ؍ Cy 19a, 2,6-C H Me
᎐
2
6
6
4
6
3
2
19b; R ؍ p-C5F4N, RЈ ؍ Cy 20a, 2,6-C6H3Me2 20b)
Complexes 8 and 9 react with phosphines (ca. 10 equiv.) giving
rise to the cationic compounds [Ru(η6-p-cymene)Cl(PR3){κ1-P-
Ph PCH P(᎐NR)Ph }][PF ] (R = p-C F CN, L = PMe 13a,
᎐
2
2
2
6
6
PMe2Ph 13b, PMePh2 13c, PPh3 13d; R =4p-C5F4N, PR3 =3PMe3
14a, PMe2Ph 14b, PMePh2 14c, PPh3 14d) (75–85% yield;
Scheme 3) with reaction times dependent on the incoming
phosphine (PMe3, ca. 4 h; PMe2Ph, ca. 12 h; PMePh2, ca. 24 h;
PPh3, ca. 30 h).
be compared with those reported in the literature for free R–P᎐
Analytical and spectroscopic data (IR and 31P-{1H}, 1H,
19F, and 13C-{1H}) for 13–14 strongly support the proposed
᎐
N–RЈ compounds.22
J. Chem. Soc., Dalton Trans., 2002, 1465–1472
1467

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observations, the formation of isocyanide complexes 19–20 in
acetonitrile can be explained assuming that complexes 17–18
are initially generated and subsequently undergo the displace-
ment of the labile acetonitrile ligand by the corresponding
isocyanide.
Synthesis of ruthenium(IV) complexes [Ru(ꢀ3:ꢀ3-C10H16)Cl2-
{ꢁ1-P-Ph PCH P(᎐NR)Ph }] (R ؍ SiMe 21, p-C F CN 22,
᎐
2
2
2
3
6
4
p-C F N 23) and [Ru(ꢀ3:ꢀ3-C H )Cl{ꢁ2-P,N-Ph PCH P(᎐NH)-
᎐
5
4
10 16
2
2
Ph2}][BF4] 24
The coordination chemisty of the dimeric Ru() complex
[{Ru(η3:η3-C10H16)(µ-Cl)Cl}2] is clearly related to that of
[{Ru(η6-arene)(µ-Cl)Cl}2] although the former has been much
less developed.23 In this context, we believed it to be of interest
to compare the hemilabile properties of the iminophosphorane-
phosphine ligands 1–3 in both metallic fragments. As expected,
the treatment of dichloromethane solutions of [{Ru(η3:η3-
C10H16)(µ-Cl)Cl}2] with two equivalents of 1–3 results in the
cleavage of the chloride bridges and the clean formation of
mononuclear bis(allyl)-ruthenium() complexes [Ru(η3:η3-
C H )Cl {κ1-P-Ph PCH P(᎐NR)Ph }] (R = SiMe 21, p-C F -
CN 22, p-C5F4N 23; 77–97% yield) (Scheme 5).
᎐
10 16
2
2
2
2
3
6
4
Scheme 3 Reactivity of complexes 8–9 towards neutral ligands.
Elemental analyses and NMR spectroscopic data of com-
pounds 21–23 support the proposed formulations (details are
given in the Supplementary Information†). Significantly, the 31P-
{1H} NMR spectra display doublet signals (2J(PP) = 32.9–35.4)
formulations (see Tables S7–S10 provided as Supplementary
Information†). In particular, the 31P-{1H} NMR spectra are
very informative showing, in addition to the expected reson-
ances of the monodentate phosphine, a doublet signal (2J(PP) =
35.7–37.2) for the iminophosphorane unit in the range 8.4–
13.2 ppm and a doublet of doublets (2J(PP) = 52.9–57.0 and
35.7–37.2) for the diphenylphosphino group of the Ph2PCH2-
in the ranges δP Ϫ7.6 to 7.5 (Ph P᎐N) and 17.9–19.5 (Ph P)
᎐
2
2
which compare well with those of the complexes [Ru(η6-p-
cymene)Cl {κ1-P-Ph PCH P(᎐NR)Ph }] (R = SiMe 4, p-
᎐
2
2
2
2
3
C6F4CN 5, p-C5F4N 6). In addition, both 1H and 13C-{1H}
NMR spectra show a single set of signals for the two allylic
moieties suggesting that the two halves of the 2,7-dimethylocta-
2,6-diene-1,8-diyl skeleton are in equivalent environments, as
expected for the formation of a simple equatorial adduct.23
However, all attempts to generate cationic complexes struc-
turally related to 8–9, by treatment of fluorinated derivatives
22–23 with NaPF6 or AgBF4 under different reaction con-
ditions failed, and instead complicated reaction mixtures of
P(᎐NR)Ph ligands at 19.3–29.3 ppm. In agreement with the
᎐
2
chirality of the metal, the methylenic PCH2P protons become
inequivalents appearing in the 1H NMR spectra as two
unresolved multiplets in the range δH 1.66–4.66. As expected,
the PCH2P carbon resonates in the 13C-{1H} NMR spectra as a
doublet of doublets (J(CP) = 60.3–80.4 (P()) and 13.7–17.5
(P())) at δC 20.35–24.58. Complexes 8–9 also react with pyr-
idine, in dichloromethane at room temperature, to afford the
related compounds [Ru(η6-p-cymene)Cl(py){κ1-P-Ph2PCH2P-
1
uncharacterized products were obtained. Remarkably, the H
(᎐NR)Ph }][PF ] (R = p-C F CN 15; R = p-C F N 16) (Scheme
᎐
2
6
6
4
5
4
NMR spectra of these mixtures do not show the presence of the
octadienediyl moiety. This seems to indicate, by comparison
with previous observations,24 that a reductive elimination of the
organic fragment to give ruthenium() species has taken place.
In contrast, we have found that [Ru(η3:η3-C10H16)Cl2{κ1-P-
3) which were isolated in 92 and 84% yield, respectively, and
fully characterized (see the Supplementary Information†). In
accordance with the lack of hemilabile reactivity of complex 7
towards anionic ligands, no reaction is either observed with
phosphines or pyridine.
Ph PCH P(᎐NSiMe )Ph }] 21 cleanly reacts with AgBF , in
᎐
2
2
3
2
4
Although solutions of complexes 8 and 9 in dichloromethane
or THF remain unchanged in the presence of isocyanides, the
treatment of 8–9 with an excess (ca. 10 equiv.) of cyclohexyl
isocyanide or 2,6-dimethylphenyl isocyanide in acetonitrile
slowly (ca. 12 h) generates complexes [Ru(η6-p-cymene)Cl-
dichloromethane at room temperature, to afford the cationic
derivative [Ru(η3:η3-C H )Cl{κ2-P, N -Ph PCH P(᎐NH)Ph }]-
᎐
10 16
2
2
2
[BF4] 24 (96% yield; Scheme 5) after cleavage of the N-SiMe3
bond. This different behaviour can be explained on the basis of
the steric hindrance between the bulky octadienediyl moiety
and the iminophosphorane substituent. This effect seems to
decrease when the fluoro-aromatic rings of 22–23 are replaced
by hydrogen, allowing the chelation of the ligand. The reac-
tivity of 24 towards neutral and anionic ligands has been also
explored but complicated reaction mixtures of uncharacterized
species were in all the cases observed.
(CNRЈ){κ1-P-Ph PCH P(᎐NR)Ph }][PF ] (R = p-C F CN, RЈ =
᎐
2
2
2
6
6
4
Cy 19a, 2,6-C6H3Me2 19b; R = p-C5F4N, RЈ = Cy 20a, 2,6-
C6H3Me2 20b) (73–82% yield; Scheme 4). Elemental analyses
and spectroscopic data are in accordance with the proposed
formulations (see the Supplementary Information†). The most
significant spectroscopic features of 19–20 are those concerning
the coordinated isocyanide ligand: (i) (IR) the typical absorp-
tion band in the range 2138–2181 cmϪ1, and (ii) (13C-{1H}
NMR) a characteristic doublet signal (2J(CP) = 9.8–15.8)
at ca. 146 ppm. The reactions seem to proceed through the
Conclusions
6
1
᎐
acetonitrile complexes [Ru(η -p-cymene)Cl(N᎐CMe){κ -P-
In this work the preparation of the first ruthenium() and
() complexes containing iminophosphorane-phosphines Ph2-
᎐
Ph PCH P(᎐NR)Ph }][PF ] (R = p-C F CN 17, R = p-C F N
᎐
2
2
2
6
6
4
5
4
18) which are formed when 8 and 9 are dissolved in acetonitrile
(Scheme 4) as inferred by 31P-{1H} NMR spectroscopy which
shows signals at 8.7 and 24.6 (d, 2J(PP) = 37.3) ppm for 17, and
PCH P(᎐NR)Ph starting from the readily accessible dimers
᎐
2 2
[{Ru(η6-p-cymene)(µ-Cl)Cl}2] and [{Ru(η3:η3-C10H16)(µ-Cl)-
Cl}2] is reported. They belong to two types of derivatives: (a)
κ1-P-monodentate complexes [Ru(η6-p-cymene)Cl2{κ1-P-Ph2-
2
at 10.1 and 25.5 (d, J(PP) = 35.7) ppm for 18. All attempts to
isolate 17 and 18 failed, leading instead to the precursors 8 and
9 quantitatively after evaporation of the solvent. The revers-
ibility of this process evidences clearly the hemilability of these
heterodifunctional P/N-donor ligands. On the basis of these
PCH P(᎐NR)Ph }] (R = SiMe , p-C F CN, p-C F N) and
᎐
2 2 3 6 4 5 4
[Ru(η3:η3-C H )Cl {κ1-P-Ph PCH P(᎐NR)Ph }] (R = SiMe ,
᎐
10 16
2
2
2
2
3
p-C6F4CN, p-C5F4N), and (b) κ2-P, N -cationic complexes
[Ru(η6-p-cymene)Cl{κ2-P, N -Ph PCH P(᎐NR)Ph }][PF ] (R =
᎐
2
2
2
6
1468
J. Chem. Soc., Dalton Trans., 2002, 1465–1472

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Scheme 4 Reactivity of complexes 8–9 towards isocyanides.
Scheme 5 Coordination of iminophosphorane-phosphine ligands on a bis(allyl)-ruthenium() moiety.
H, p-C6F4CN, p-C5F4N) and [Ru(η3:η3-C10H16)Cl{κ2-P, N -
Ph PCH P(᎐NH)Ph }][BF ]. For the first time it has been
Experimental
᎐
2
2
2
4
General comments
shown that iminophosphorane-phosphines can act as hemilabile
ligands providing the presence of bulky and strong electron
withdrawing substituents (R = p-C6F4CN, p-C5F4N). Thus, we
have found that the Ru-N bond in chelate complexes [Ru(η6-p-
The manipulations were performed under an atmosphere of dry
nitrogen using vacuum-line and standard Schlenk techniques.
All reagents were obtained from commercial suppliers and used
without further purification. Solvents were dried by standard
methods and distilled under nitrogen before use. The com-
pounds [{Ru(η6-p-cymene)(µ-Cl)Cl}2],16 [{Ru(η3:η3-C10H16)-
cymene)Cl{κ2-P, N-Ph PCH P(᎐NR)Ph }][PF ] (R = p-C F CN,
᎐
2
2
2
6
6
4
p-C5F4N) can be readily cleaved, under very mild reaction con-
ditions, by a large variety of anionic and neutral ligands. The
chelate ring opening processes have led to the formation of the
(µ-Cl)Cl}2]23b and Ph PCH P(᎐NR)Ph (R = SiMe , p-C F CN,
᎐
2
2
2
3
6
4
stable complexes [Ru(η6-p-cymene)X {κ1-P-Ph PCH P(᎐NR)-
p-C5F4N)6b,10a were prepared by following the methods reported
in the literature. Analytical and spectroscopic data for all
he complexes reported in this paper have been provided as
Supplementary Information.†
᎐
2
2
2
Ph2}] (X = Br, I, N3, CN, NCO) and [Ru(η6-p-cymene)Cl-
(L){κ1-P-Ph PCH P(᎐NR)Ph }][PF ] (L = PR , py, CNRЈ),
᎐
2
2
2
6
3
respectively. Moreover, complexes [Ru(η6-p-cymene)Cl{κ2-P, N -
Ph PCH P(᎐NR)Ph }][PF ] (R = p-C F CN, p-C F N) undergo
᎐
2
2
2
6
6
4
5
4
a reversible chelate ring opening process in acetonitrile (Scheme
4). In conclusion, the synthesis of these series of ruthenium
complexes has shown that these heterodifunctional P/N-donor
ligands can be used as good hemilabile ligands. Studies devoted
to its application in homogeneous catalysis are now in progress.
Preparations
[Ru(ꢀ6-p-cymene)Cl {ꢁ1-P-Ph PCH P(᎐NR)Ph }] (R ؍ Si-
᎐
2
2
2
2
Me3 4, p-C6F4CN 5, p-C5F4N 6). General procedure. A solution
of [{Ru(η6-p-cymene)(µ-Cl)Cl}2] (0.245 g, 0.4 mmol) and the
J. Chem. Soc., Dalton Trans., 2002, 1465–1472
1469

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corresponding iminophosphorane-phosphine 1–3 (0.8 mmol) in
30 cm3 of dichloromethane was stirred at room temperature for
1 h and then evaporated to dryness. The orange solid residue
was washed with pentane (3 × 10 cm3) and dried in vacuo. 4:
Yield: 0.473 g, 76%. 5: Yield: 0.548 g, 78%. 6: Yield: 0.472 g,
69%.
80%. 14a: Time: 4 h. Yield: 0.395 g, 76%. 14b: Time: 12 h. Yield:
0.435 g, 79%. 14c: Time: 24 h. Yield: 0.437 g, 75%. 14d: Time:
30 h. Yield: 0.472 g, 77%.
[Ru(ꢀ6-p-cymene)Cl(py){ꢁ1-P-Ph PCH P(᎐NR)Ph }][PF ]
᎐
2
2
2
6
(R ؍ p-C6F4CN 15; R ؍ p-C5F4N 16). General procedure. A
solution of the corresponding complex [Ru(η6-p-cymene)Cl{κ2-
[Ru(ꢀ6-p-cymene)Cl{ꢁ2-P,N-Ph PCH P(᎐NR)Ph }][PF ] (R؍
P, N -Ph PCH P(᎐NR)Ph }][PF ] 8–9 (0.5 mmol) and pyridine
᎐
2
2
2
6
᎐
2
2
2
6
(0.404 cm3, 5 mmol) in 40 cm3 of dichloromethane was stirred
at room temperature for 12 h and then evaporated to dryness.
The yellow solid residue was washed with diethyl ether (3 ×
30 cm3) and dried in vacuo. 15: Yield: 0.491 g, 92%. 16: Yield:
0.438 g, 84%.
H 7, p-C6F4CN 8, p-C5F4N 9). Method A. A solution of the
corresponding neutral complex [Ru(η6-p-cymene)Cl2{κ1-P-
Ph PCH P(᎐NR)Ph }] 4–6 (0.5 mmol) and NaPF (0.084 g,
᎐
2
2
2
6
0.5 mmol for 4; 1g, 6 mmol for 5–6) in 40 cm3 of methanol was
stirred at room temperature for 12 h and then evaporated to
dryness. The residue was extracted with ca. 20 cm3 of dichloro-
methane, the suspension filtered through Kieselguhr, and the
resulting solution concentrated to dryness. The orange solid
obtained was washed with diethyl ether (3 × 20 cm3) and dried
in vacuo. 7: Yield: 0.322 g, 79%. 8: Yield: 0.415 g, 84%. 9: Yield:
0.385 g, 80%.
[Ru(ꢀ6-p-cymene)Cl(CNRЈ){ꢁ1-P-Ph PCH P(᎐NR)Ph }][PF ]
᎐
2
2
2
6
(R ؍ p-C6F4CN, RЈ ؍ Cy 19a, 2,6-C6H3Me2 19b; R ؍ p-C5F4N,
RЈ ؍ Cy 20a, 2,6-C6H3Me2 20b). General procedure. A solution
of the corresponding complex [Ru(η6-p-cymene)Cl{κ2-P, N -
Ph PCH P(᎐NR)Ph }][PF ] 8–9 (0.5 mmol) and the appropri-
᎐
2
2
2
6
ate isocyanide (5 mmol) in 40 cm3 of acetonitrile was stirred at
room temperature for 12 h and then evaporated to dryness. The
yellow solid residue was washed with diethyl ether (3 × 30 cm3)
and dried in vacuo. 19a: Yield: 0.422 g, 77%. 19b: Yield: 0.425 g,
76%. 20a: Yield: 0.440 g, 82%. 20b: Yield: 0.400 g, 73%.
Method B. A suspension of [{Ru(η6-p-cymene)(µ-Cl)Cl}2]
(0.153 g, 0.25 mmol), the corresponding iminophosphorane-
phosphine 1–3 (0.5 mmol) and NaPF6 (0.084 g, 0.5 mmol for 4;
1 g, 6 mmol for 5–6) in 40 cm3 of methanol was stirred at room
temperature for 12 h and then evaporated to dryness. The resi-
due was extracted with ca. 20 cm3 of dichloromethane, the sus-
pension filtered through Kieselguhr, and the resulting solution
concentrated to dryness. The orange solid obtained was washed
with diethyl ether (3 × 20 cm3) and dried in vacuo. Yields ≈ 75%.
[Ru(ꢀ3:ꢀ3-C H )Cl {ꢁ1-P-Ph PCH P(᎐NR)Ph }] (R ؍ Si-
᎐
10 16
2
2
2
2
Me3 21, p-C6F4CN 22, p-C5F4N 23). General procedure A solu-
tion of [{Ru(η3:η3-C10H16)(µ-Cl)Cl}2] (0.616 g, 1 mmol) and
the corresponding iminophosphorane-phosphine 1–3 (2 mmol)
in 30 cm3 of dichloromethane was stirred at room temper-
ature for 5 min and then evaporated to dryness. The yellow
solid residue was washed with hexane (3 × 10 cm3) and dried
in vacuo. 21: Yield: 1.482 g, 95%. 22: Yield: 1.708 g, 97%. 23:
Yield: 1.319 g, 77%.
[Ru(ꢀ6-p-cymene)X {ꢁ1-P-Ph PCH P(᎐NR)Ph }] (R
؍ p-
᎐
2
2
2
2
C6F4CN, X ؍ Br 10a, I 10b, N3 10c, CN 10d, NCO 10e; R ؍
p-C5F4N, X ؍ Br 11a, I 11b, N3 11c, CN 11d, NCO 11e).
General procedure. A solution of the corresponding complex
[Ru(η6-p-cymene)Cl{κ2-P, N -Ph PCH P(᎐NR)Ph }][PF ] 8–9
᎐
2
2
2
6
(0.5 mmol) and the appropriate sodium salt NaX (8 mmol) in
40 cm3 of methanol was stirred at room temperature for 8 h
and then evaporated to dryness. The residue was extracted
with ca. 90 cm3 of diethyl ether, the suspension filtered through
Kieselguhr, and the resulting solution concentrated to dryness
to give a yellow–orange solid. 10a: Yield: 0.401 g, 83%. 10b:
Yield: 0.414 g, 78%. 10c: Yield: 0.352 g, 79%. 10d: Yield: 0.296 g,
69%. 10e: Yield: 0.316 g, 71%. 11a: Yield: 0.415 g, 88%. 11b:
Yield: 0.389 g, 75%. 11c: Yield: 0.377 g, 87%. 11d: Yield: 0.384 g,
92%. 11e: Yield: 0.317 g, 73%.
[Ru(ꢀ3:ꢀ3-C H )Cl{ꢁ2-P,N-Ph PCH P(᎐NH)Ph }][BF ] 24.
᎐
10 16
2
2
2
4
A solution of [Ru(η3:η3-C H )C {κ1-P-Ph PCH P(᎐NSiMe )-
᎐
10 16
l2
2
2
3
Ph2}] 21 (0.3 g, 0.386 mmol) in 20 cm3 of dichloromethane
was treated, at room temperature and in the dark, with AgBF4
(0.08 g, 0.41 mmol) for 1 h. The resulting suspension was then
filtered through Kieselguhr and the filtrate evaporated to dry-
ness. The yellow solid residue was washed with diethyl ether
(3 × 20 cm3) and dried in vacuo. Yield: 0.218 g, 96%.
X-Ray crystal structure determination of [Ru(ꢀ6-p-cymene)-
(ꢁ1-N-NCO) {ꢁ1-P-Ph PCH P(᎐N-p-C F CN)Ph }]ؒCH Cl 10e
᎐
[Ru(ꢀ6-p-cymene)X{ꢁ2-P,N-Ph PCH P(᎐NH)Ph }][PF ] (X؍
2
2
2
6
4
2
2
2
᎐
2
2
2
6
Br 12a, I 12b, N3 12c, CN 12d, NCO 12e). General procedure. A
Crystals suitable for X-ray diffraction analysis were obtained by
slow diffusion of pentane into a saturated solution of the com-
plex in dichlorometane. Data collection, crystal, and refinement
parameters are collected in Table 1. Diffraction data were
recorded on a Nonius Kappa CCD single crystal diffractometer
using Cu-Kα radiation. Crystal-detector distance was fixed at
29 mm and a total of 1243 frames were collected using the
oscillation method, with 2Њ oscillation and 40 s exposure time
per frame. Data collection strategy was calculated with the pro-
gram Collect.25 Data reduction and cell refinement were per-
formed with the programs HKL Denzo and Scalepack.26 Unit
cell dimensions were determined from 7669 reflections with θ
between 2 and 71Њ. Symmetry equivalents and multiple observ-
ations were averaged, Rmerge = 0.079, resulting in 8148 unique
reflections of which 6753 were observed with I > 2σ(I ). Final
mosaicity was 0.444(3)Њ. All data completeness was 99.0%.
The structure was solved by Patterson methods using the
program DIRDIF.27 Isotropic full-matrix least-squares refine-
ment on F 2 using SHELXL-97 was performed.28 During the
final stages of the refinement, all positional parameters and the
anisotropic thermal parameters of all the non-H atoms were
refined. A highly disordered CH2Cl2 solvent molecule was
found which was isotropically refined. The H-atoms were geo-
metrically placed and their coordinates were refined riding on
solution of [Ru(η6-p-cymene)Cl{κ2-P, N -Ph PCH P(᎐NH)Ph }]-
᎐
2
2
2
[PF6] 7 (0.407 g, 0.5 mmol) and the corresponding sodium salt
NaX (8 mmol) in 40 cm3 of methanol was stirred at room
temperature for 6 h and then evaporated to dryness. The residue
was extracted with ca. 20 cm3 of dichloromethane, the sus-
pension filtered through Kieselguhr, and the resulting solution
concentrated to dryness. The yellow–orange solid obtained was
washed with diethyl ether (3 × 20 cm3) and dried in vacuo. 12a:
Yield: 0.378 g, 88%. 12b: Yield: 0.344 g, 76%. 12c: Yield: 0.377 g,
92%. 12d: Yield: 0.358 g, 89%. 12e: Yield: 0.345 g, 84%.
[Ru(ꢀ6-p-cymene)Cl(PR ){ꢁ1-P-Ph PCH P(᎐NR)Ph }][PF ]
᎐
3
2
2
2
6
(R ؍ p-C6F4CN, PR3 ؍ PMe3 13a, PMe2Ph 13b, PMePh2 13c,
PPh3 13d; R ؍ p-C5F4N, PR3 ؍ PMe3 14a, PMe2Ph 14b,
PMePh2 14c, PPh3 14d). General procedure. A solution of the
corresponding complex [Ru(η6-p-cymene)Cl{κ2-P, N -Ph2PCH2-
P(᎐NR)Ph }][PF ] 8–9 (0.5 mmol) and the appropriate phos-
᎐
2
6
phine (5 mmol) in 40 cm3 of dichloromethane was stirred at
room temperature for the time indicated below and then evap-
orated to dryness. The yellow solid residue was washed with
diethyl ether (3 × 30 cm3) and dried in vacuo. 13a: Time: 4 h.
Yield: 0.452 g, 85%. 13b: Time: 12 h. Yield: 0.473 g, 84%. 13c:
Time: 24 h. Yield: 0.463 g, 78%. 13d: Time: 30 h. Yield: 0.500 g,
1470
J. Chem. Soc., Dalton Trans., 2002, 1465–1472

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Table 1 Crystal data and structure refinement for 10e
Empirical formula
Formula weight
T /K
RuC44H36F4N4O2P2ؒCH2Cl2
976.70
200(2)
λ/Å
Crystal system
Space group
1.54184
Triclinic
P1
¯
Unit cell dimensions
a/Å
12.5484(4)
b/Å
c/Å
12.7604(5)
13.8396(7)
α/Њ
β/Њ
101.654(3)
92.512(3)
γ/Њ
91.765(3)
2166.49(15)
V/Å3
Z
2
Dc/g cmϪ3
µ/mmϪ1
F(000)
1.497
5.271
992
Crystal size/mm
Theta range for data collection/Њ
0.28 × 0.22 × 0.08
3.26–70.01
Index ranges
Ϫ15 ≤ h ≤ 15, Ϫ15 ≤ k ≤ 15, 0 ≤ l ≤ 16
8149/8148 [R(int) = 0.0000]
99.0%
Reflections collected/unique
Completeness to theta = 70.01Њ
Refinement method
Full-matrix least-squares on F 2
8148/0/541
Data/restraints/parameters
Goodness-of-fit on F 2
Final R indices [I > 2σ(I )]
R indices (all data)
1.098
R1 = 0.0637, wR2 = 0.1836
R1 = 0.0708, wR2 = 0.1975
2.872 and Ϫ1.357
Largest diff. peak and hole/e ÅϪ3
6 See for example: (a) V. A. Gilyarov, V. Y. Kovtum and M. I.
Kabachmich, Izv. Akad. Nauk SSSR, Ser. Khim., 1967, 5, 1159; (b)
K. V. Katti and R. G. Cavell, Inorg. Chem., 1989, 28, 413; (c) K. V.
Katti, R. J. Batchelor, F. W. B. Einstein and R. G. Cavell, Inorg.
Chem., 1990, 29, 808; (d ) R. G. Cavell, R. W. Reed, K. V. Katti,
M. S. Balakrishna, P. W. Collins, V. Mozol and I. Bartz, Phosphorus,
Sulfur Silicon, 1993, 76, 9; (e) M. W. Avis, M. Goosen, C. J. Elsevier,
N. Veldman, H. Kooijman and A. L. Spek, Inorg. Chim. Acta, 1997,
264, 43; ( f ) P. Molina, A. Arques, A. García and M. C. Ramírez de
Arellano, Tetrahedron Lett., 1997, 38, 7613.
7 For reviews on the Staudinger reaction see: (a) Y. G. Gololobov,
I. N. Zhmurova and L. F. Kasukhin, Tetrahedron, 1981, 37, 437;
(b) Y. G. Gololobov and L. F. Kasukhin, Tetrahedron, 1992, 48,
1353.
8 (a) R. G. Cavell and K. V. Katti, Can. Pat. Appl. CA 2,024,284,
1992; (b) R. G. Cavell, B. Creed, L. Gelmini, D. J. Law, R.
McDonald, A. R. Sanger and A. Somogyvari, Inorg. Chem., 1998,
37, 757.
9 (a) K. V. Katti and R. G. Cavell, Organometallics, 1991, 10, 539; (b)
P. Molina, A. Arques, A. García and M. C. Ramírez de Arellano,
Eur. J. Inorg. Chem., 1998, 1359; (c) J. Vicente, A. Arcas, D. Bautista
and M. C. Ramírez de Arellano, Organometallics, 1998, 17, 4544; (d )
R. S. Pandurangi, K. V. Katti, L. Stillwell and C. L. Barnes, J. Am.
Chem. Soc., 1998, 120, 11364.
their parent atoms. The final cycle of full-matrix least-squares
refinement based on 8148 reflections and 541 parameters con-
verged to final values of R1 (F 2 > 2σ(F 2)) = 0.0637, wR2 (F 2
>
2σ(F 2)) = 0.1836, R1 (F 2) = 0.0708, wR2(F 2) = 0.1975. The
function minimized was ([Σw(Fo Ϫ Fc2)/Σw(Fo )]1/2 where w =
2
2
1/[σ2(Fo ) ϩ (0.1077P)2] with σ(Fo ) from counting statistics and
2
2
2
P = (Max (Fo , 0) ϩ 2Fc2)/3. The maximum residual electron
density is located near to the disordered solvent molecule.
Atomic scattering factors were taken from the International
Tables for X-ray Crystallography.29 Geometrical calculations
were made with PARST.30 The crystallographic plots were
made with PLATON.31 All calculations were performed at the
Scientific Computer Centre of the University of Oviedo using
VAX and DEC-ALPHA computers.
CCDC reference number 174365.
See http://www.rsc.org/suppdata/dt/b1/b110442j/ for crystal-
lographic data in CIF or other electronic format.
Acknowledgements
This work was supported by the Ministerio de Ciencia y
Tecnología (Projects BQU2000–0219 and BQU2000–0227) of
Spain and the EU (COST programme D12/0025/99). S. E. G.-G.
thanks the Ministerio de Ciencia y Tecnología (MCyT) for the
award of a Ph.D. grant.
10 (a) K. V. Katti and R. G. Cavell, Organometallics, 1989, 8, 2147; (b)
A. Saravanamuthu, D. M. Ho, M. E. Kerr, C. Fitzgerald, M. R. M.
Bruce and A. E. Bruce, Inorg. Chem., 1993, 32, 2202.
11 (a) K. V. Katti and R. G. Cavell, Organometallics, 1988, 7, 2236; (b)
K. V. Katti, B. D. Santarsiero, A. A. Pinkerton and R. G. Cavell,
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Catal., 1994, 91, 175; (d ) D. J. Law, G. Bigam and R. G. Cavell, Can.
J. Chem., 1995, 73, 635; (e) J. Li, R. McDonald and R. G. Cavell,
Organometallics, 1996, 15, 1033.
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