G. Sa´nchez-Cabrera et al. / Journal of Organometallic Chemistry 599 (2000) 313–316
315
Crystals of both 1 and 2 were studied by X-ray
diffraction2 and the results are shown in Fig. 1. Consis-
tent with spectroscopic evidence, the structure of 1,
consists of an Ru3 triangle with two of the edges
bridged by dppa ligands. The metal triangle and the
two five-membered metallacycles are close to forming a
plane. A least-squares calculation of the best planes
formed by the nine atoms was carried out and the
largest deviations from planarity are 0.01423 [P(1)] and
hydrogen atom bonded to N(2) and the oxygen atom of
one of the water molecules. This interaction might be a
factor of influence in the almost planar conformation
adopted by the metal–ligand cycles.
Crystals of 2 show crystallographically imposed sym-
metry and only half of the molecule is present in the
asymmetric unit. As proposed, the structure consists of
a triangle of ruthenium atoms with one of the edges
bridged by a dppa ligand. The edge supported by the
chelate ligand is slightly shorter than the other two
,
0.1315 A [N(1)]. The coplanarity of the rings formed by
,
dppa bridging a metal–metal edge had already been
observed in [CoPd2(m3-CO)2(m2-{(Ph2P)2N(CH3)}3]PF6
[4] and in [Ru3(m3-E)2{m2-P,P%-(PPh2)2NH}(CO)7] (E=
S, Se) [8] but it is important to establish that the
dppa-bridged edge is very long in the last compound
and presumably does not hold a metal–metal bond,
thus allowing larger flexibility of the metallacyclic ring
formed. Non-planarity has also been observed in
[Ru4(m3-E)2{m2-P,P%-(PR2)2NH}(CO)9].
(2.8287(11) versus 2.8545(10) A), which are equivalent.
This trend is similar to that observed in the structures
of [Ru3(CO)10(dppm)] [11] and of [Ru3(CO)10{m-
Ph2PN(Et)PPh2}] [3], although the difference between
RuꢀRu distances is not as large as that observed in the
second compound.
The chelate ring in this structure is twisted. The
P(1)ꢀRu(1)ꢀRu(1a)ꢀP(1a) torsion angle is 20.35°. Phos-
phorus–ruthenium distances are similar to those in 1
and in the Ph2PN(Et)PPh2 derivative, although they are
longer than in [Ru3(CO)10(dppm)]. This could be ex-
plained in terms of lower backbonding towards the
phosphorus atom. PꢀN distances are somewhat longer
than those in the free ligand [12] and within the range
of those observed in other dppa complexes [5,10].
Two of the metal–metal distances in 1 are identical
while the third one, bridged by one of the dppa ligands,
,
is only slightly longer (2.823(2) versus 2.833(3) A) (see
Table 1). These values are very similar to those de-
scribed for the ‘supported’ metal–metal bonds in
[Ru3(CO)8(dppm)2] [9]. All RuꢀP bonds in 1 are equiva-
lent and are also similar to those in the dppm analogue.
Bond parameters within the dppa ligand show some
interesting trends. Both ligands have a PꢀN bond
longer than the other one within the same dppa frag-
3. Supplementary material
,
ment (1.728(9) and 1.660(10) A in one ligand and
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 136343 for compound 1 and
136342 for compound 2. Copies of this information
may be obtained free of charge from: The Director,
CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK
,
1.724(9) and 1.674(10) A in the other, values shorter
and longer than the one observed in the free ligand
(1.692(2) A)), although the large standard deviations in
,
the values in 1 do not allow a clear difference to be
assured. Similar behavior was observed in [Pd4(m-
Cl)2(m-dppm)2(m-dppa)2](PF6)2 [4] but no significant dif-
ferences are observed in either [Co2Pt(m3-CO)-
(CO)6(m-dppa)] [10], [Ru3(CO)10{m-Ph2PN(Et)PPh2}]
[3], or [Pt(dppa)2][BF4]2 · MeCN [2].
(Fax:
+44-1223-336-033; e-mail: deposit@ccdc.
cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
Five water molecules were found in the unit cell of 1
and an analysis of non-bonding distances shows the
Acknowledgements
,
existence of a short contact (2.457 A) between the
We thank CONACYT for grants (to G.S.C. and
E.V.G.B.) and for support towards the acquisition of
an X-ray diffractometer (Project F00084) and NMR
spectrometers (Projects F563 and 166-0/PAD).
2 X-ray data for both compounds were collected in a CAD4,
Enraf–Nonius diffractometer in crystals mounted in capillary tubes.
Both structures were solved by direct methods using SHELX-93 [14].
All non-hydrogen atoms were found in Fourier maps and refined
anisotropically. Hydrogen atoms from phenyl groups were fixed in
idealized positions and their positions refined. All calculations were
carried out on computers. Compound 1. C56H52N2O13P4Ru3, F.W.
References
,
1388.05, monoclinic, P21/c. a=16.629(3), 15.724(3), c=23.653(5) A,
3
,
i=94.22°. V=6167.9 A . v=0.888. 2q Range 2–49.96°. 10 624
unique reflections, 4475 observed (\4|), R=0.0819, wR=0.2152.
Compound 2 C34H21N1O10P2Ru3 · C2H2Cl6, F.W.=1207.40, mono-
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,
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3
,
126.48(3), V=4505.4(15) A . Z=4, v=1.472. 2q Range 2–49.94°,
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