New arylruthenium(II) complexes of the P,C,P′-coordinating terdentate monoanionic aryl ligands [C6H2(CH2PPh 2)2-2,6-R-4]- (PCP-R-4; R = Ph, H).

Article abstract of DOI:10.1021/om9603833

The synthesis and characterization of new, five-coordinate, diamagnetic, 16-electron arylruthenium(II) complexes [Ru^IIX{C₆H₂(CH₂PPh₂) ₂-2,6-R-4}(PPh₃)] (1, X = Cl, R = H; 2, X = Cl, R = Ph; 3, X = OSO₂CF₃, R = H; 4, X = I, R = H) are described. These coordinatively unsaturated complexes contain a stable C_aryl-Ru σ-bond resulting from pseudomeridional terdentate P,C,P′-bonding of the monoanionic {C₆H₂(CH₂PPh₂) ₂-2,6-R-4}^- ligand (general abbreviation PCP-R-4; for R = H and R = Ph, abbreviated as PCP and PCP-Ph, respectively) that also provides two P → Ru bonds. This bonding mode of the PCP-R-4 ligands adopted in complexes 1-4 means that these species are structurally closely related to the complexes [RuCl{C₆H₂(CH₂NMe ₂)2-2,6-R-4}(PPh₃)] (R = H, Ph) in which there is terdentate N,C,N′-coordination. Complexes 1 and 2 were synthesized via cyclometalation reactions of the respective neutral diphosphine compounds C₆H₃(CH₂PPh₂)₂-2,6-R-4 (general abbreviation PC(H)P-R-4; for R = H and R = Ph, abbreviated as PC(H)P and PC(H)P-Ph, respectively) with [Ru^IICl₂(PPh₃)₄]. The complex [Ru^II(OTf)(PCP)(PPh₃)], 3, prepared by reaction of 1 with AgOTf (OTf = OSO₂CF₃ = triflate), has the triflate anion bound to ruthenium in noncoordinating solvents. On the NMR time scale complex 3 in solution exhibits temperature-dependent fluxionality that is associated with reversible changes of the complex stereochemistry. The triflate PCP complex 3 reacts cleanly with the neutral N-donor ligand 2,2′:6′,2″-terpyridine (terpy) to afford [Ru^II(PCP)(terpy)][OTf], 5. However, whereas the reaction of terpy with the PCP-Ph complex 2 affords [Ru^II(PCP-Ph)(terpy)]Cl, 6, its reaction with PCP chloro complex 1 generates a mixture of products. These reactivities of PCP and PCP-Ph complexes (1-3) toward terpy are compared and contrasted with those of related ruthenium complexes containing the monoanionic aryldiamine ligand {C₆H₂(CH₂NMe₂) ₂-2,6-R-4}^- (abbreviated as NCN-R-4).

Full text of DOI:10.1021/om9603833

Organometallics 1996, 15, 5687-5694
5687
New Ar ylr u th en iu m (II) Com p lexes of th e
P ,C,P ′-Coor d in a tin g Ter d en ta te Mon oa n ion ic Ar yl
Liga n d s [C6H2(CH2P P h 2)2-2,6-R-4]- (P CP -R-4; R ) P h , H).
Syn th esis of 16-Electr on Sp ecies [Ru IIX(P CP -R-4)(P P h 3)]
(X ) Cl, I, OTf) a n d Th eir Rea ctivity tow a r d th e Neu tr a l
Ter d en ta te N-Don or Liga n d 2,2′:6′,2′′-Ter p yr id in e (ter p y)
Thomas Karlen, Paulo Dani, David M. Grove, Pablo Steenwinkel, and
Gerard van Koten*
Department of Metal-Mediated Synthesis, Debye Institute, Utrecht University,
Padualaan 8, 3584 CH Utrecht, The Netherlands
Received May 20, 1996X
The synthesis and characterization of new, five-coordinate, diamagnetic, 16-electron
arylruthenium(II) complexes [RuIIX{C6H2(CH2PPh2)2-2,6-R-4}(PPh3)] (1, X ) Cl, R ) H; 2,
X ) Cl, R ) Ph; 3, X ) OSO2CF3, R ) H; 4, X ) I, R ) H) are described. These coordinatively
unsaturated complexes contain a stable Caryl-Ru σ-bond resulting from pseudomeridional
terdentate P,C,P′-bonding of the monoanionic {C6H2(CH2PPh2)2-2,6-R-4}- ligand (general
abbreviation PCP-R-4; for R ) H and R ) Ph, abbreviated as PCP and PCP-Ph, respectively)
that also provides two P f Ru bonds. This bonding mode of the PCP-R-4 ligands adopted
in complexes 1-4 means that these species are structurally closely related to the complexes
[RuCl{C6H2(CH2NMe2)2-2,6-R-4}(PPh3)] (R ) H, Ph) in which there is terdentate N,C,N′-
coordination. Complexes 1 and 2 were synthesized via cyclometalation reactions of the
respective neutral diphosphine compounds C6H3(CH2PPh2)2-2,6-R-4 (general abbreviation
PC(H)P-R-4; for R ) H and R ) Ph, abbreviated as PC(H)P and PC(H)P-Ph, respectively)
with [RuIICl2(PPh3)4]. The complex [RuII(OTf)(PCP)(PPh3)], 3, prepared by reaction of 1 with
AgOTf (OTf ) OSO2CF3 ) triflate), has the triflate anion bound to ruthenium in
noncoordinating solvents. On the NMR time scale complex 3 in solution exhibits temper-
ature-dependent fluxionality that is associated with reversible changes of the complex
stereochemistry. The triflate PCP complex 3 reacts cleanly with the neutral N-donor ligand
2,2′:6′,2′′-terpyridine (terpy) to afford [RuII(PCP)(terpy)][OTf], 5. However, whereas the
reaction of terpy with the PCP-Ph complex 2 affords [RuII(PCP-Ph)(terpy)]Cl, 6, its reaction
with PCP chloro complex 1 generates a mixture of products. These reactivities of PCP and
PCP-Ph complexes (1-3) toward terpy are compared and contrasted with those of related
ruthenium complexes containing the monoanionic aryldiamine ligand {C6H2(CH2NMe2)2-
2,6-R-4}- (abbreviated as NCN-R-4).
In tr od u ction
have been stabilized as isolable complexes.5,6 Further-
more, the complexes [NiX(NCN)] and various deriva-
tives can be used as homogeneous catalysts in the
Kharasch addition reaction, i.e. the addition of polyha-
logenated alkanes to alkenes with the formation of new
C-C and C-X (X ) halogen) bonds.7 Recently, it has
been found that certain manganese and tantalum
complexes containing NCN as a ligand also exhibit
interesting catalytic activity in cross-coupling reactions
of functionalized alkyl halides with alkyl Grignard
The potentially N,C,N′-terdentate monoanionic aryl
ligand [C6H3(CH2NMe2)2-2,6]- (NCN ) 2,6-bis[(dimeth-
ylamino)methyl]phenyl)1 and the related anionic P,C,P′-
coordinating bis(phosphine) ligand [C6H3(CH2PPh2)2-
2,6]- (PCP ) 2,6-bis[(diphenylphosphino)methyl]-
phenyl),2-4 depicted in Scheme 1, have attracted con-
siderable interest as tools both for controlling the reac-
tivity of metal centers in a variety of transition metal
complexes and for stabilizing complexes in unusual
geometries. For example, intermediates in oxidative
addition reactions of I2 and MeI to the PtII(NCN) moiety
(5) van Beek, J . A. M.; van Koten, G.; Smeets, W. J . J .; Spek, A. L.
J . Am. Chem. Soc. 1986, 108, 5010.
(6) (a) Grove, D. M.; van Koten, G.; Louwen, J . N.; Noltes, J . G.;
Spek, A. L.; Ubbels, H. J . C. J . Am. Chem. Soc. 1982, 104, 6609. (b)
Canty, A. J .; van Koten, G. Acc. Chem. Res. 1995, 28, 406.
* To whom correspondence should be addressed.
X Abstract published in Advance ACS Abstracts, November 15, 1996.
(1) van Koten, G. Pure Appl. Chem. 1989, 61, 1681.
(2) (a) Moulton, C. J .; Shaw, B. L. J . Chem. Soc., Dalton Trans. 1976,
1020. (b) Rimml, H.; Venanzi, L. M. J . Organomet. Chem. 1983, 259,
C6.
(3) Gorla, F.; Togni, A.; Venanzi, L. M. Organometallics 1994, 13,
1607.
(4) Pape, A.; Lutz, M.; Mu¨ller, G. Angew. Chem., Int. Ed. Engl. 1994,
33, 2281.
(7) (a) Grove, D. M.; van Koten, G.; Verschuuren, A. H. M. J . Mol.
Catal. 1988, 45, 169. (b) Grove, D. M.; Verschuuren. A. H. M.; van
Koten, G.; van Beek, J . A. M. J . Organomet. Chem. 1989, 372, C1. (c)
van de Kuil, L. A.; Veldhuizen, Y. S. J .; Grove, D. M.; Zwikker, J . W.;
J enneskens, L. W.; Drenth, W.; Smeets, W. J . J .; Spek, A. L.; van
Koten, G. Recl. Trav. Chim. Pays-Bas 1994, 113, 267. (d) Knapen, J .
W. J .; van der Made, A. W.; de Wilde, J . C.; van Leeuwen, P. W. N.
M.; Wijkens, P.; Grove, D. M.; van Koten, G. Nature 1994, 372, 659.
(e) van de Kuil, L. A.; Grove, D. M.; Zwikker, J . W.; J enneskens, L.
W.; Drenth, W.; van Koten, G. Chem. Mater. 1994, 6, 1675.
S0276-7333(96)00383-4 CCC: $12.00 © 1996 American Chemical Society

5688 Organometallics, Vol. 15, No. 26, 1996
Karlen et al.
Sch em e 1. Abbr evia tion s for Mon oa n ion ic Liga n d s
a n d Liga n d P r ecu r sor s
tions such as the reduction of ketones to alcohols in the
presence of base with 2-propanol as the reducing
agent.13
The first synthesis of complexes [RuCl(NCN-R-4)-
(PPh3)]10b and the interesting preliminary data we
obtained for their reactivity as catalysts in hydrogen
transfer and hydrogenation reactions13 have now
prompted us to investigate closely related complexes
based on the PCP ligand and its derivatives. This
publication, which deals principally with the synthesis
and characterization of ruthenium complexes of two
anionic PCP-R-4 ligands, i.e. [C6H3(CH2PPh2)2-2,6]-
(PCP)2-4 and novel [C6H2(CH2PPh2)2-2,6-Ph-4]- (PCP-
Ph), illustrates the important role that auxiliary ligands
play in determining the nature of Ru(II) species con-
taining such terdentate ligand systems. We also present
the first direct comparison of the influence of N,C,N′-
and P,C,P′-bonding in the chemistry of structurally
closely related ruthenium complexes containing terden-
tate ligands [C6H2(CH2ER′2)2-2,6-R-4]- (ER′2 ) NMe2,
PPh2) and correlate these differences with both steric
and electronic influences.
reagents and in ring-opening metathesis polymerization
reactions of cyclic alkenes, respectively.8
The aryl nucleus of NCN and PCP lends itself to
derivatization, and the family of substituted ligands
[C6H2(CH2NMe2)2-2,6-R-4]- (NCN-R-4) and [C6H2(CH2-
PPh2)2-2,6-R-4]- (PCP-R-4), Scheme 1, appears to offer
interesting potential. It is to be anticipated that the
bonding of these ligands of general formula [C6H2(CH2-
ER′2)2-2,6-R-4]- (ER′2 ) NMe2 or PPh2) will normally
comprise a Caryl to metal σ-bond which is complemented
by intramolecular coordination of the donor atoms of the
two ER′2 groups to afford a meridional geometry; with
NCN the N-M-N angles are then typically 145-165°.1
With this geometry the metal center is embedded in an
organic cleft, and it is clear that the electronic and steric
properties of the complex will be sensitive to the nature
of both the heteroatomic ER′2 group and the para
substituent R on the aryl ring. The latter was clearly
demonstrated by the series of complexes [NiX(NCN-R-
4)] (R ) NMe2, Me, H, Cl, C(O)Me), whose catalytic and
redox properties could be electronically tuned by varia-
tion of the group R para to the Cipso-Ni bond.7,9
In an extension of our work to ruthenium complexes
with either N,C,N′- or P,C,P′-coordinating ligands we
have been able to isolate stable mononuclear aryl-
diamine complexes with the specific NCN-R-4 ligands
in which R is H (NCN)10a or Ph (NCN-Ph),10b and we
have already reported interesting bimetallic complexes
which result from oxidative C-C coupling reactions of
some of these species.11 It is worth noting that platinum
complexes containing chiral derivatives of PCP as
ligands have been successfully synthesized.12 Signifi-
cantly, some of the 16-electron NCN-R-4 ruthenium
complexes efficiently catalyze hydrogen-transfer reac-
Resu lts
The known diphosphine compound C6H4(CH2PPh2)2-
1,3 (PC(H)P)2b reacts in CH2Cl2 with [RuIICl2(PPh3)4]14
to afford, in a direct cyclometalation reaction, the five-
coordinate complex [RuCl(PCP)(PPh3)], 1, that has been
isolated in moderate yield as a green, air-sensitive solid.
On the basis of its characteristic 1H, 13C, and 31P NMR
data in CD2Cl2, 1 is proposed to have a square-
pyramidal geometry, with the PPh3 ligand occupying the
1
apical position as illustrated in Scheme 2. In the H
NMR spectrum of 1 one observes, for example, diaste-
reotopic benzylic hydrogen atoms indicative of the
absence of a molecular symmetry plane through the
benzylic carbon atoms. Furthermore, in the 31P NMR
spectrum there is a small coupling between the two
equivalent PPh2 groups of PCP and the PPh3 ligand
(2J (PP) ) 31.7 Hz) indicative of the PPh3 ligand being
positioned cis to both PPh2 groups. In the 13C NMR
spectrum of 1 the Cipso atom affords a doublet resonance
arising from coupling to the PPh3 group (2J (CP) ) 16.6
Hz); the low magnitude of this coupling constant is in
accordance with an angle Cipso-Ru-PPh3 that deviates
considerably from 180°. The absence of coupling be-
tween the P atoms of PCP and Cipso suggests they are
both positioned cis to Cipso as expected for a pseudome-
ridional P,C,P′-binding geometry. The proposed struc-
ture for 1 is analogous to the square-pyramidal struc-
ture previously reported for the related NCN iodo
complex [RuI(NCN)(PPh3)].10a
The course of the reaction of the diphosphine PC(H)P
with [RuCl2(PPh3)3]/PPh3 (that has to involve a cyclo-
metalation step)12 was followed by 31P NMR spectros-
copy and is depicted in Figure 1. Early in the reaction
(8) Donkervoort, J . G.; Rietveld, M. H. P.; van Koten, G. Unpublished
results.
(9) van de Kuil, L. A.; Luitjes, H.; Grove, D. M.; Zwikker, J . W.; van
der Linden, J . G. M.; Roelofsen, A. M.; J enneskens, L. W.; Drenth, W.;
van Koten, G. Organometallics 1994, 13, 468.
(10) (a) Sutter, J .-P.; J ames, S. L.; Steenwinkel, P.; Grove, D. M.;
Veldman, N.; Smeets, W. J . J .; Spek, A. L.; van Koten, G. Organome-
tallics 1996, 15, 941. (b) Steenwinkel, P.; J ames, S. L.; Grove, D. M.;
Veldman, N.; Spek, A. L.; van Koten, G. Chem. Eur. J ., in press.
(11) Sutter, J .-P.; Grove, D. M.; Beley, M.; Collin, J .-P.; Veldman,
N.; Spek, A. L.; Sauvage, J .-P.; van Koten, G. Angew. Chem. 1994, 33,
1282.
(12) (a) Gorla, F.; Venanzi, M. Organometallics 1994, 13, 43. (b) A
similar process has been described for the cyclometalation reaction of
PC(H)P (P ) PCy2) with RhCl3: Cross, R. J .; Kennedy, A. R.;
Manojlovic-Muir, L.; Muir, K. W. J . Organomet. Chem. 1995, 493, 243.
(13) For example, it proved possible to reduce cyclohexanone to
cyclohexanol with conversions of better than 90% at a substrate to
catalyst ratio as high as 2000:1. Moreover, such complexes also
catalyze the selective reduction by dihydrogen of an activated CdC
bond in alkenes such as benzylideneacetone: Karlen, T.; van Koten,
G. Manuscript in preparation.
(14) It is known that [RuCl2(PPh3)4] in solution is predominantly
present as [RuCl2(PPh3)3] (+PPh3) due to ligand dissociation pro-
cesses: (a) Hallman, P. S.; Stephenson, T. A.; Wilkinson, G. Inorg.
Synth. 1970, XII, 237. (b) Hoffman, P. R.; Caulton, K. G. J . Am. Chem.
Soc. 1975, 97, 4221.

Ru(II) Complexes of P,C,P′-Coordinating Ligands
Organometallics, Vol. 15, No. 26, 1996 5689
Sch em e 2. Syn th esis Over view
F igu r e 1. 31P NMR spectrum (CD2Cl2) of the reaction
mixture of PC(H)P with [RuCl2(PPh3)3]/PPh3 that affords
1 via species I.
Sch em e 3. Syn th esis of 1
a new set of signals consisting of a triplet (84.05 ppm,
2
2J (PP) ) 31.6 Hz) and a doublet (39.51 ppm, J (PP) )
31.6 Hz) appear. The loss of intensity of this set of
signals with time was proportional to the intensity gain
of the resonances belonging to the end product 1, and
these resonances have been assigned to an as yet
unidentified species I. The “triplet + doublet” pattern
is consistent with I containing two chemically equiva-
lent phosphorus nuclei coupled to one chemically dis-
tinct phosphorus atom, and in this respect one can see
that the chemical shifts and the coupling constants of
the resonances belonging to I are very similar to those
of 1. We believe that this species may be dinuclear, but
unfortunately, when all of the starting material [RuII-
Cl2(PPh3)4] has reacted to I, the final product 1 is
already present to such a degree that it has not proved
possible to isolate this species in a pure form.
In a synthesis analogous to the one described for the
preparation of 1, the new neutral diphosphine com-
pound C6H3(CH2PPh2)2-1,3-Ph-5 (PC(H)P-Ph); see Ex-
perimental Section) reacts with [RuIICl2(PPh3)4] to
afford [RuIICl(PCP-Ph)(PPh3)], 2. The NMR data of 2
are very similar to those obtained for 1, though with
the anticipated changes in resonance patterns that
result from the presence of a phenyl group, rather than
complex [Ru(OTf)(PCP)(PPh3)], 3 (Scheme 2). In CH2-
Cl2 the 31P NMR spectrum at 298 K consists of a slightly
broadened signal (for the PPh3 ligand) and a sharp
doublet resonance, but at 220 K the resonances have
shifted significantly and the spectrum consists of a
2
triplet and a doublet with a J (PP) coupling constant of
31.7 Hz. The low value of 2J (PP) indicates that the PCP
ligand has preserved a pseudomeridional binding mode
with an associated cis arrangement between the PPh2
and the PPh3 groups. Moreover, a low-temperature (LT)
1H NMR spectrum shows diastereotopic benzylic hy-
drogens, and a LT 13C NMR (CD2Cl2) spectrum reveals
2
a doublet for Cipso with a small J (CP) of 17 Hz. From
these data it can be concluded that 3 has, like 1, a
mutual cis arrangement of Cipso and the PPh3 which is
retained at low temperature. The temperature-depend-
ent changes in the spectra of 3 point to fluxional
behavior that we believe may be associated with η1-O-
to-η2-O,O′ binding of the triflate anion.
Alternative processes involving dissociation of the OTf
group to form a 14-electron four-coordinate ionic species
seem unlikely (particularly in toluene), and the absence
of effective bridging ligands in combination with the
steric bulk of the PPh2 groups and the PPh3 ligand (see
Discussion) would seem to exclude associative intermo-
lecular processes that involve dimer formation or solvent
coordination. We wished to investigate this process
further but the poor solubility of 3 in toluene at low
temperature has hampered NMR studies in this solvent.
Surprisingly, although the 31P NMR spectrum of 3 in
the coordinating solvent THF at room temperature was
simple, at low temperature the spectrum comprises a
complex set of signals that indicates a situation in which
a proton, positioned para to Cipso. On the basis of
spectroscopic and microanalytical data, complex 2 is
postulated to be a mononuclear square-pyramidal com-
plex, isostructural with 1, as depicted in Scheme 2.
Although complexes 1 and 2 are 16-electron, five-
coordinate species, i.e. coordinatively unsaturated, in
solution, they show no fluxional behavior on the NMR
time scale at room temperature either in noncoordinat-
ing solvents such as benzene and CH2Cl2 or in the
potentially coordinating solvent THF.
Addition of an equimolar amount of AgOTf (OTf )
OSO2CF3 ) triflate) to PCP complex 1 in dichlo-
romethane results in replacement of the chloride ligand
by the OTf monoanion to afford the green, air-sensitive

5690 Organometallics, Vol. 15, No. 26, 1996
Karlen et al.
one or more THF molecules have added to the coordi-
natively unsaturated complex 3 to afford a mixture of
products.
differences between N-donor (-NMe2) and P-donor
(-PPh2) ligand sites in terms of electronic and steric
influence on ruthenium(II) species. These differences
should be quite pronounced because of the different
sizes of the heteroatoms as well as the fact that the
NMe2 and the PPh2 groups contain very different
substituents (alkyl vs aryl). We have already reported
that late transition metal complexes with anionic ligands
[C6H3(CH2NR′R′′)2-2,6]- are most easily formed when
the substituents R′ and R′′ are both Me, i.e. NCN.1
Compared to NCN those ligands with amine groups
-NEt2, -NMeEt, -NMe(iPr), and -NMe(tBu),15 as well
as with pyrrolidine7c and proline16 ring systems, are
expected to have nitrogen donor atoms that are stronger
Lewis bases, but the ability of these groups to coordinate
is severely influenced by steric factors. Compared to
phosphorus, nitrogen has a relatively small atomic
radius, and therefore N-donor ligands have larger cone
angles than their phosphorus analogs.1 This difference
explains why a ligand like 1,3-bis[(di-tert-butylphosphi-
no)methyl]benzene (PCP-tBu),17 despite its apparent
significant bulk, can form not only four-coordinate
complexes of Pd, Pt, Ni, and Rh but also six-coordinate
Ir and Rh species when small auxiliary ligands (e.g. CO,
Cl, etc) are present.14b,17,18 For the aryldiamine systems
[C6H3(CH2NR′R′′)2-2,6]- also electronic effects of the R′
and R′′ substituents play a much larger role than in
related phosphine chemistry. For example, the -NMe-
(Ph) group of the ligand [C6H3(CH2NMe(Ph))2-2,6]- is
found to be a poor N-donor (i.e. weak Lewis base) group
because of electron delocalization of the lone pair and
this group is unable to substitute PEt3 in the complex
[NiCl{C6H3(CH2NMe(Ph))2-2,6}(PEt3)2] so that this aryl-
diamine ligand is only monodentate η1-C-bonded to
nickel and the nonbonded N-atoms have a trigonal
planar geometry.15
F or m a tion of P CP -R-4 Com p lexes. The differ-
ences between heteroatom donor groups are apparent
both in the formation of complexes [RuCl{C6H2(CH2-
ER′2)2-R-4}(PPh3)] (ER′2 ) NMe2, PPh2) and in their
physical characteristics and reactivity. So far all at-
tempts to synthesize NCN-R-4 ruthenium complexes via
cyclometalation reactions have failed, so that in practice
the synthesis of NCN ruthenium complexes requires a
transmetalation reaction of (2,6-bis[(dimethylamino)-
methyl]phenyl)lithium with a suitable Ru(II) starting
material.10
This paper has shown that complexes [RuIICl(PCP-
R-4)(PPh3)] are readily accessible by a cyclometalation
route. In the general mechanism of a cyclometalation
reaction that results in the potential formation of [RuCl-
{C6H2(CH2ER′2)2-R-4}(PPh3)] species, as shown in
Scheme 4, it is the nature of the ruthenium starting
material and the coordinative property of -NMe2 vs
-PPh2 which are of primary importance; the nature of
the C-H bond to be metalated is similar in both PC-
-(H)P-R-4 and NC(H)N-R-4.
The iodo complex [RuI(PCP)(PPh3)], 4 (Scheme 2), has
been obtained by two different synthetic routes. In the
first route chloro complex 1 is reacted with an excess of
KI in MeOH at reflux for 4 days. The second route
involves the conversion of triflate complex 3 with an
equimolar amount of KI in MeOH, and this procedure
affords 4 in high yield within a few hours at room
1
temperature. Since H, 13C, and 31P NMR data for 4
are very similar to those obtained for the chloro complex
1, we conclude that these two complexes are analogous
and isostructural.
Reaction of 2,2′:6′,2′′-terpyridine (terpy) with the PCP
complexes 1-3 affords new products of the type [Ru-
(PCP-R)(terpy)]X. The red, air-stable ionic complex [Ru-
(PCP)(terpy)][OTf], 5, which is formed readily within a
few hours from triflate complex 3 and terpy in MeOH
at reflux, has been fully characterized by NMR spec-
troscopy in CD2Cl2 and elemental microanalysis. The
1H NMR spectrum of 5 shows equivalent benzylic
hydrogens, indicative of a molecular mirror plane
containing the benzylic carbon atoms. Only one singlet
resonance (for PCP) is found by 31P NMR spectroscopy,
so confirming the absence of a PPh3 ligand. In the 13C
NMR spectrum of this species there is a singlet reso-
nance for Cipso, consistent with the two equivalent PPh2
groups being in a cis position to Cipso. The overall
structure is thus believed to be an ionic one with a
triflate anion and a complex monocation having a six-
coordinate Ru(II) center (see Scheme 2).
In contrast, if chloro PCP complex 1 is reacted with
1 equiv of terpy in MeOH at reflux a mixture of products
is obtained of which approximately 60% (based on 31P
NMR data) can be attributed to the complex [Ru(PCP)-
(terpy)]Cl, but unfortunately, attempts to purify this
product by column chromatography or by exchange of
the counterion failed.
However, the chloro PCP-Ph complex 2 reacts, albeit
slowly but in a well-defined way, with terpy in MeOH
at reflux to afford within 2 days the red, air-stable com-
plex [Ru(PCP-Ph)(terpy)]Cl, 6, as the only product. The
spectroscopic data for 6 are similar to those obtained
for 5 and are consistent with the ionic structure depicted
schematically in Scheme 2. The 13C NMR spectrum of
6 was particularly useful for characterizing this complex
since it showed in the aromatic region all the expected
resonances (Experimental Section). Attempts to pre-
pare ionic terpy complexes like 5 and 6 directly via a
cyclometalation reaction between [RuIII(OdCMe2)3-
(terpy)][X]3 (X ) BF4, OTf) and PC(H)P or PC(H)P-Ph
were partially successful and afforded, as judged by 31
P
NMR spectroscopy, ca. 30-50% of the desired material
in the product mixture, though it did not prove possible
to isolate pure products from these mixtures.
Discu ssion
(15) van Beek, J . A. M.; van Koten, G.; Ramp, M. J .; Coenjaarts, N.
C.; Grove, D. M.; Goubitz, K.; Zoutberg, M. C.; Stam, C. H.; Smeets,
W. J . J .; Spek, A. L. Inorg. Chem. 1991, 30, 3059.
(16) van de Kuil, L. A.; Veldhuizen, Y. S. J .; Grove, D. M.; Zwikker,
J . W.; J enneskens, L. W.; Drenth, W.; Smeets, W. J . J .; Spek, A. L.;
van Koten, G. J . Organomet. Chem. 1995, 488, 191.
(17) Moulton, C. J .; Shaw, B. L. J . Chem. Soc., Dalton Trans. 1976,
1020.
Gen er a l Obser va tion s. We have now shown that
it is possible with the diphosphine monoanionic ligands
[C6H2(CH2PPh2)2-2,6-R-4]- to prepare 16-electron Ru-
(II) complexes [RuCl(PCP-R)(PPh3)] that are analogous
to complexes [RuCl(NCN-R)(PPh3)] containing the aryl-
diamine system [C6H2(CH2NMe2)2-2,6-R-4]- (Scheme 1).
This affords an unprecedented opportunity to examine
(18) Nemeh, S.; J ensen, C.; Binamira-Soriaga, E.; Kaska, W. C.
Organometallics 1983, 2, 1442.

Ru(II) Complexes of P,C,P′-Coordinating Ligands
Organometallics, Vol. 15, No. 26, 1996 5691
Sch em e 4. Cyclom eta la tion Rou tes A a n d B
Ta ble 1. 31P a n d 13C NMR Da ta for P CP -R-4 a n d
NCN-R-4 Ru th en iu m Com p lexesa
The first route for cyclometalation (Scheme 4, path
A) involves prior coordination of the heteroatom donor
sites to ruthenium, and this assists subsequent attack
of the coordinated metal center to the appropriately
positioned arene C-H bond;12,17 this route is the one
that is responsible for the formation of ruthenium PCP-
R-4 complexes. Since NC(H)N fails to cyclometalate
with [RuCl2(PPh3)3]/PPh3 (in solution),14 we conclude
that this neutral aryldiamine is less effective than PC-
(H)P-R in replacing the PPh3 ligands in this starting
material.
A second route for cyclometalation (Scheme 4, path
B) would comprise an electrophilic attack of the metal
center on the aryl ligand with direct formation of an
arenonium intermediate. In such an intermediate
(where the M-C bond is ortho to the “free” heteroatom-
containing substituents) further reaction involving re-
moval of H+ can be assisted by the heteroatoms.19,20
However, this route seems only to be viable in the case
of NC(H)N. For the PC(H)P ligand electrophilic attack
of a metal center on an arene C-H bond is prevented
by strong inter- and intramolecular ligation of the excess
of phosphorus donor atoms (of both PPh3 and the -PPh2
groups) that is present.
31P NMR, δ (ppm)
13C NMR, δ (ppm)
ipso (2J (CP))b
Ru species
PPh2
PPh3
C
PCP-R-4 Complexes
[RuCl(PCP)(PPh3)], 1
[RuCl(PCP-Ph)(PPh3)], 2
[Ru(OTf)(PCP)(PPh3)], 3
[RuI(PCP)(PPh3)], 4
[Ru(PCP)(terpy)][OTf], 5
[Ru(PCP-Ph)(terpy)]Cl, 6
36.5
36.7
38.2c
36.2
42.5
42.7
81.3
80.8
75.9c
77.2
172.7 (16.6)
173.2 (17.3)
164.6 (17.0)
177.3 (16.0)
183.5 (s)
182.3 (s)
NCN-R-4 Complexes
91.1
[RuCl(NCN)(PPh3)]d
185.8 (15.3)
186.6 (16)
187.2 (14.1)
[RuCl(NCN-Ph)(PPh3)]e
[RuI(NCN)(PPh3)]d
90.4
89.0
a
Measured in CD2Cl2. Chemical shifts referenced to external
standard H3PO4 (
31P NMR) or TMS (13C NMR). Coupling con-
b
stant between Cipso and PPh3 in Hz. All Cipso resonances are
doublets unless indicated otherwise. c Broad resonances at room
temperature. Data at 220 K: δ(PPh3) 78.9 ppm; δ(PPh2) 36.7 ppm.
From ref 10a. e From ref 10b.
d
metal center into low-lying empty phosphorus-based
orbitals. These electronic factors account for the fact
that [RuCl(NCN)(PPh3)] has in its UV/vis spectrum a
λmax at 557 nm (ꢀ ) 1287 M-1 cm-1 10a
whereas the
)
corresponding green PCP complex 1 has a λmax at 630
nm (ꢀ ) 1250 M-1 cm-1); in a qualitative outline back-
donation into the -PPh2 groups leads to a smaller
MLCT (metal to ligand charge transfer) bandgap in 1
and therefore to a shift of this transition to lower
frequency.
Our view that route A is responsible for the formation
of the PCP ruthenium complexes is supported by the
fact that it is only the C-H bond between the two
CH2PPh2 arms (position 2) of PC(H)P that is metalated,
even though the outside positions (4 and 6) are sterically
less hindered. The driving force for the displacement
of three PPh3 ligands from [RuCl2(PPh3)3]/PPh3 for one
PC(H)P molecule is likely to be the property of this bis-
(phosphine)14b to act as a neutral pseudo trans-spanning
ligand. As shown in Scheme 4, the resulting schematic
intermediate in route A has the Cipso-H bond forced
close to the ruthenium center whereby C-H activation
is facilitated.
Sp ectr oscop ic Asp ects of P CP -R-4 a n d NCN-R-4
Com p lexes. The electronic characteristics of the PCP
complex 1 were expected to differ from those of the
corresponding NCN complex [RuCl(NCN)(PPh3)] since
each of the -NMe2 ligating groups has almost exclu-
sively σ-donating properties whereas the P-donor center
in the -PPh2 group can have both electron-donating and
electron-accepting character, i.e. the -PPh2 groups
attenuate their donating effect by accepting electron
density from ruthenium via back-donation from the
The 31P NMR data for the PPh3 ligands and -PPh2
groups in the ruthenium PCP-R-4 complexes 1-6 (col-
lected in Table 1) together with data for PPh3 ligands
in some related NCN-R species clearly reflect changes
in the electronic and steric influences operative at and
around the metal center. For example one notices that
the -PPh2 resonances move to higher ppm values (i.e.
the P atoms become more deshielded) through the
introduction of π-electron-accepting groups (e.g terpy)
or by the removal of σ-electron-donating groups (e.g. Cl-)
and that in general these resonances are less sensitive
than those of PPh3 to changes within the ligand sphere.
In detail one sees that there is very little difference
between equivalent complexes of PCP and PCP-Ph or
between complexes of NCN and NCN-Ph. For example,
comparison of the -PPh2 resonance position of PCP
complex 1 at 36.5 ppm, with that of PCP-Ph complex 2
at 36.7 ppm shows that the introduction of a phenyl
group para to the Cipso-Ru bond affords only a modest
deshielding of +0.2 ppm; for the PPh3 resonances in the
same complexes the effect of the phenyl group is to
decrease the deshielding by 0.5 ppm. However, the
influence of the auxiliary ligands is more dramatic.
(19) Valk, J .-M.; van Belzen, R.; Boersma, J .; Spek, A. L.; van Koten,
G. J . Chem. Soc., Dalton Trans. 1994, 2293.
(20) (a) Alsters, P. L.; Engel, P. F.; Hogerheide, M. P.; Copijn, M.;
Spek, A. L.; van Koten, G. Organometallics 1993, 12, 1831. (b)
Markies, B. A.; Wijkens, P.; Kooijman, H.; Spek, A. L.; Boersma, J .;
van Koten, G. J . Chem. Soc., Chem. Commun. 1992, 1420.

5692 Organometallics, Vol. 15, No. 26, 1996
Karlen et al.
When the Cl- ligand in 1 is replaced by triflate anion
(a weaker σ-donor) to afford 3, the shift for the PPh3
resonances decreases 5.4 ppm from 81.3 to 75.9 ppm;
the effect on the PPh2 resonances is more modest and
affords, in contrast, a shift increase of 1.7 ppm. The
replacement of the donor ligands PPh3 and Cl- in
neutral complex 2 for the strongly π-accepting terpy in
cationic complex 6 results in a shift of the -PPh2
resonance from 36.7 to 42.5 ppm. This increased
deshielding of 5.8 ppm reflects clearly the different
nature and coordination of these two species.
3 is replaced readily by the better donor I-, the reactions
of the five-coordinate PCP complexes 1 and 2 with KI
are relatively slow. Since exchange of the chloride in
[RuCl(NCN)(PPh3)] for iodide is fast at room temp-
erature,10a the reluctance of Cl- to be exchanged for I-
in PCP complexes 1 and 2 can be interpreted as being
due to the electron-accepting character of the PPh2
groups that in a dissociative mechanism leads to
destabilization of the intermediate cation [Ru(PCP)-
(PPh3)]+. The influence of the leaving group X on the
reactivity of 16-electron complexes [RuX(PCP-R-4)-
(PPh3)] (X ) Cl, 1 and 2; X ) OTf, 3; I, 4) was also
demonstrated in their reactions with the terdentate
N,N′,N′′-donor ligand terpy. On the one hand, to form
ionic complex 6 from chloro complex 2 strenuous reac-
tion conditions over a prolonged time were required with
significant amounts of byproducts, probably due to
cyclometalation of a terpy ring, being generated. On
the other hand, the presence of a better leaving group
(OTf-) in the starting material 3 led to fast coordination
of the three N-donor atoms of terpy to afford ionic
complex 5 while no side products were formed. We
ascribe the fact that PCP-Ph complex 2 does react with
terpy, whereas PCP complex 1 does not, to the weak
electron-donating character of the phenyl group para
to the Cipso-Ru bond in complex 2 that makes the
chloride anion a better leaving group. A similar effect
was not observed for NCN-R-4 complexes [RuCl(NCN-
R-4)(PPh3)](R ) H, Ph), where the halide is expected to
be much less strongly bound than in the PCP-R-4
analogs, and terpy readily replaces the PPh3 and Cl-
ligands in such complexes to give the corresponding
cationic terpy species.10
The 31P NMR resonance for the PPh3 ligand in PCP-
R-4 complexes is found some 9-12 ppm to upfield of the
corresponding resonance in analogous NCN-R-4 com-
plexes. This result cannot be explained by the expected
donor characteristics of the heteroatoms in these ligands,
and an explanation has to be sought in the relative
steric constraints in these complexes and their effects
on the metal coordination sphere. Since the determined
cone angle of PPh3 is 145° 21 and of NMe3 is 132° 22 (so
giving an idea of the difference to be expected for related
R-PPh2 and R-NMe2 groups), one might anticipate
that steric congestion in the ruthenium PCP-R-4 com-
plexes would be more severe than in the NCN-R-4
analogs. However, molecular modeling23 shows that as
a consequence of the larger atomic radius of phosphorus
compared to nitrogen and of the lower steric bulk of the
slim flat phenyl groups compared to the spherical and
rigidly positioned N-methyl groups it is the NCN-R-4
species that are more crowded. These differences are
primarily reflected in the relative positions of the chloro
atom with respect to the apical phosphorus atom with
the NCN analog having the most pronounced square-
pyramidal structure. It is interesting to see that 13C
NMR data for Cipso in analogous ruthenium PCP-R-4
and NCN-R-4 complexes (Table 1) also show trends that
run contrary to electron-donating properties of these two
ligands. Unexpectedly, it is the NCN-R-4 ligands that
provide the higher Cipso chemical shifts in combination
Su m m a r y
With the monoanionic [C6H2(CH2PPh2)2-2,6-R-4]-
ligand, PCP-R-4, it has been possible to prepare com-
plexes of the type [RuX(PCP-R)(PPh3)] in which a 16-
electron ruthenium(II) center is stabilized. These new
complexes allow structural and chemical parallels to be
drawn with analogous complexes containing aryl-
diamine ligands [C6H2(CH2NMe2)2-2,6-R-4]-, NCN-R-
4. As in the NCN-R-4 complexes, the PCP-R-4 system
is bound in a pseudomeridional manner to ruthenium
and a square-pyramidal overall geometry is usual. The
main differences in reactivity found between PCP-R-4
and NCN-R-4 complexes are due to the enhanced
acceptor character and the decreased steric demand of
-PPh2 groups compared to -NMe2 groups. The PCP-
R-4 complexes are thermally stable arylruthenium(II)
species, some of which show fluxional behavior in
solution, in which the Cipso-Ru σ-bond is remarkably
robust and is, for example, inert to reagents such as
boiling methanol. The triflate complex [Ru(OTf)(PCP)-
(PPh3)], 3, for which the NCN analog is unknown, has
recently allowed entry into chemistry which includes an
interesting, but as yet not fully characterized, species
that probably contains one monoanionic PCP ligand and
one neutral PC(H)P ligand.25
2
with smaller J (CP) values. In ongoing studies we are
investigating further the significance of these NMR
data/structure correlations.10b
Ch em ical Aspects of P CP -R-4 an d NCN-R-4 Com -
p lexes. From a chemical point of view, one of the
noticeable features of the PCP complex 1 (and other
PCP-R-4 complexes reported here) is the much lower
sensitivity toward oxidation by O2 than its NCN analog.
This is understandable since, compared to a -PPh2
group, the -NMe2 group with its purely electron-
donating character (vide supra) will give rise to a higher
electron density on the Ru(II) center and, therefore, to
a lower redox potential. At the same time a higher
oxidation state of the metal, e.g. Ru(III), is more
stabilized by coordination of the hard nitrogen donor
site.11,24
The electronic differences between PCP and NCN
complexes are also seen in the ability of an auxiliary
metal-bound ligand to function as a leaving group.
Whereas the very weakly coordinating ligand OTf- in
Exp er im en ta l Section
(21) Tolman, C. A. Chem. Rev. 1977, 77, 313.
(22) Seligson, A. L.; Trogler, W. C. J . Am. Chem. Soc. 1991, 113,
89.
(23) CAChe scientific software, using augmented MM2 parameters.
(24) (a) Beley, M.; Collin, J .-P.; Louis, B.; Metz, J . P.; Sauvage, J .-
P. J . Am. Chem. Soc. 1991, 113, 8521-8522. (b) Beley, M.; Collin,
J .-P.; Sauvage, J .-P. Inorg. Chem. 1991, 113, 8521.
The complexes [RuCl2(PPh3)4]14 and [RuCl(NCN-R-4)(PPh3)]10
and the diphosphine 1,3-bis[(diphenylphosphino)methyl]ben-
(25) Dani, P.; Karlen, T.; Grove, D. M.; Spek, A. L.; Smeets, W. J .
J .; van Koten, G. Manuscript in preparation.

Ru(II) Complexes of P,C,P′-Coordinating Ligands
Organometallics, Vol. 15, No. 26, 1996 5693
zene, PC(H)P,2 were prepared as described in the literature.
Purchased chemicals were used without further purification.
Solvents were dried by standard procedures and stored under
nitrogen. All manipulations were carried out using Schlenk
Cl{C6H3(CH2P P h 2)2-2,6}(P P h 3)], 1. A solution of PC(H)P
(500 mg, 1.1 mmol) in CH2Cl2 (10 mL) was added to
[RuCl2(PPh3)4] (1.2 g, 1.0 mmol) in CH2Cl2 (30 mL). The
mixture was heated at reflux for 3 days, concentrated to 5 mL,
and then layered with pentane (30 mL). Upon agitation, a
green powder precipitated from solution. The solid was filtered
off, washed with pentane, and dried in vacuo. Yield: 0.51 g,
58% (mp >200 °C). 1H NMR (200.13 MHz, CD2Cl2): δ 2.53
techniques in
a dry nitrogen atmosphere, unless stated
otherwise. Elemental analyses were performed by Dornis und
Kolbe, Mikroanalytisches Laboratorium (Mu¨lheim, Germany).
NMR spectra were recorded on a Bruker AC-200 or Bruker
AC-300 spectrometer; 13C and 31P NMR spectra were recorded
with broadband proton decoupling at 300 K unless stated
otherwise. For NMR data, the following abbreviations are
used: s, singlet; d, doublet; t, triplet; m, multiplet; tap, apparent
triplet; td, triplet of doublets; br, broad.
Syn th esis of 1-P h en yl-3,5-d im eth ylben zen e, C6H3-P h -
1-Me2-3,5. A solution of phenyl boronic acid (33.4 g, 184 mmol)
in MeOH (80 mL) was added dropwise to a vigorously stirred
mixture of 2 M aqueous Na2CO3 (150 mL) and toluene (300
mL), containing 1-bromo-3,5-dimethylbenzene (25 g, 135 mmol).
[Pd(PPh3)4] (1 g, 0.87 mmol) was added, and the mixture was
stirred for 3 days. Addition of CH2Cl2 (500 mL) and 2 M
aqueous Na2CO3 (800 mL) containing concentrated ammonia
(100 mL) resulted in partitioning of the mixture. The sepa-
rated organic layer was washed with saturated brine (150 mL)
and dried over MgSO4, and the volatilies were removed in
vacuo. The crude product was purified by flash distillation to
give a colorless oil, bp 84-86 °C/0.6 mmHg (lit.: 155 °C/16
mmHg).26 Yield: 23.3 g, 95%. MS (EI, 70 eV): m/z (rel
intensity) 182 (M+, 100%), 167 (58.2), 152 (13.1), 89 (11.5), 76
(12.2). 1H NMR (200.13 MHz, CDCl3): δ 2.45 (s, 6 H, CH3),
7.1-7.8 (m, 8 H, aromatic). 13C NMR (50.3 MHz, CDCl3): δ
21.76, 125.5, 127.44, 127.56, 129.02, 129.28, 138.52, 141.65,
141.87. nD20: 1.5949 (lit.: 1.5952).27
Syn th esis of 1-P h en yl-3,5-bis(br om om eth yl)ben zen e,
C6H3-P h -1-(CH2Br )2-3,5. To a solution of C6H3-Ph-1-Me2-3,5
(25.5 g, 0.14 mol) in dry CCl4 (300 mL) were added N-
bromosuccinimide (47.88 g, 0.269 mol) and 2,2′-azobis(isobu-
tyronitrile), AIBN (0.5 g). The mixture was heated at gentle
reflux until vigorous boiling indicated the start of the reaction,
and stirring without further heating was continued until
boiling ceased. The resulting mixture was then heated at
reflux for 12 h. The solution was cooled to room temperature
and filtered and the filtrate collected. The solid residue was
extracted with CCl4 (100 mL), and the filtrate and extract were
combined. Evaporation of this solution to dryness on a rotary
evaporator afforded the crude product. Pure white crystalline
product was obtained by two subsequent crystallizations from
hexanes. Yield: 17.1 g, 36%. MS (EI, 70 eV): m/z (rel
intensity) 342, 340, 338 (M+, 4.1, 8.2, 4.1%), 261, 259 (90.1),
180 (100), 165 (41.5), 89 (51.4), 63 (22.4). 1H NMR (200.13
MHz, CDCl3): δ 4.54 (s, 4 H, CH2), 7.26-7.6 (m, 8 H, aromatic).
13C NMR (50.3 MHz, CDCl3): δ 32.86, 127.18, 127.89, 127.95,
128.35, 128.91, 138.91, 139.89, 147.21.
Syn th esis of 1-P h en yl-3,5-bis[(d ip h en ylp h osp h in o)-
m eth yl]ben zen e, C6H3-P h -1-(CH2P P h 2)2-3,5, P C(H)P -P h .
Sodium (1.28 g, 55.7 mmol), PPh3 (7.3 g, 27.9 mmol), and NH4-
Br (2.7 g, 27.6 mmol) were sequentially added to liquid
ammonia (200 mL) at -78 °C at intervals of 30 min. To this
solution was added C6H3-Ph-1-(CH2Br)2-3,5 (4.6 g, 13.8 mmol)
as a slurry in dry Et2O. The resulting mixture was stirred
for 6 h at -78 °C, after which the external cooling was removed
and the solvents were allowed to evaporate in a stream of
nitrogen overnight. The residue was washed twice with water,
once with MeOH, and twice with hexane. The resulting white
solid product was recrystallized from CH2Cl2/Et2O. Yield: 5.84
g, 77% (mp 152-153 °C). 1H NMR (200.13 MHz, CD2Cl2): δ
3.3-3.43 (s, 4 H, CH2), 6.8-7.5 (m, 28 H, aromatic). 31P NMR
(80.96 MHz, CD2Cl2): δ -9.2 (s). Anal. Calcd for C38H32P2:
C, 82.92; H, 5.81. Found: C, 83.10; H, 5.81.
2
4
(td br, 2J (HH) 15.9 Hz, | J (HP) + J (HP)| not resolved, 2 H,
2
2
4
CH2), 3.49 (td, J (HP) 15.9 Hz, | J (HP) + J (HP)| 6 Hz, 2 H,
CH2), 6.7-8.3 (m, 38 H, aromatic). 31P NMR (80.96 MHz, CD2-
2
2
Cl2): δ 36.5 (d, J (PP) 31.7 Hz, PPh2), 81.3 (t, J (PP) 31.7 Hz,
PPh3). 13C NMR (75.4 MHz, CD2Cl2): δ 40.77 (tap, J (CP) 15
Hz, CH2), 123.6-138.7 (13 resonances: 5 s, 2 d, 4 t, 2 m), 151.8
(tap, J (CP) 8.7 Hz), 172.7 (d, 2J (CP) 16.6 Hz, Cipso). Anal. Calcd
for C50H42ClP3Ru + 0.5 CH2Cl2: C, 66.33; H, 4.81. Found: C,
66.45; H, 5.05.
Syn t h esis of (4-P h en yl-2,6-bis[(d ip h en ylp h osp h in o)-
m eth yl]p h en yl)ch lor o(tr ip h en ylp h osp h in e)r u th en iu m -
(II), [Ru IICl{C6H2(CH2P P h 2)2-2,6-P h -4}(P P h 3)], 2. A solu-
tion of PC(H)P-Ph (0.8 g, 1.45 mmol) in CH2Cl2 (20 mL) was
added dropwise to a stirred solution of [RuCl2(PPh3)4] (1.65 g,
1.35 mmol) in CH2Cl2 (20 mL) at room temperature. The
mixture was heated at reflux for 15 h and subsequently
concentrated to 5 mL. Upon addition of Et2O/pentane dark
green microcrystals formed, which were filtered off and washed
with pentane followed by drying in vacuo. Yield: 1.0 g, 78%
(mp >200 °C). 1H NMR (300.13 MHz, CD2Cl2): δ 2.5 (td br,
2
2J (HP) 16.1 Hz, | J (HP) + 4J (HP)| not resolved, 2 H, CH2),
2
2
4
3.57 (td, J (HP) 16.1 Hz, | J (HP) + J (HP)| 6 Hz, 2 H, CH2),
31
6.8-8.0 (m, 42 H, aromatic).
P NMR (80.96 MHz, CD2Cl2):
δ 36.7 (d, 2J (PP) 31.8 Hz, PPh2), 80.8 (t, 2J (PP) 31.8 Hz, PPh3).
13C NMR (75.4 MHz, CD2Cl2): δ 39.1 (tap, J (CP) 15.3 Hz, CH2),
121-142 (13 resonances: 5 s, 2 d, 4 t, 2 m), 151.3 (t, J (CP)
8.6 Hz), 173.2 (d, J (CP) 17.3 Hz, Cipso). Anal. Calcd for
C
56H46ClP3Ru: C, 70.94; H, 4.85. Found: C, 70.76; H, 4.94.
Syn t h esis of (2,6-Bis[(d ip h en ylp h osp h in o)m et h yl]-
ph en yl)tr iflu or om eth an esu lfon ato(tr iph en ylph osph in e)-
r u t h en iu m (II), [R u II(OSO2CF 3){C6H 3(CH 2P P h 2)2-2,6}-
(P P h 3)], 3. AgOTf (166 mg, 0.65 mmol) was added to a stirred
solution of 1 (500 mg, 0.57 mmol) in CH2Cl2 (20 mL). After 3
h of stirring at room temperature under exclusion of light, the
green solution was separated from the formed white precipi-
tate by centrifugation. The solution was evaporated to dry-
ness, and the residue was extracted with benzene (30 mL).
After removal of the benzene, the residue was dissolved 10
mL of CH2Cl2. Addition of pentane resulted in the formation
of a green powder, which was collected and washed twice with
hexane (20 mL) and dried in vacuo. Yield: 300 mg, 53% (mp
172 °C (dec)). 1H NMR (200.13 MHz, CD2Cl2): δ 2.31-2.49
2
4
(td br, 2J (HH) 16.5 Hz, | J (HP) + J (HP)| not resolved, 2 H,
CH2), 3.32-3.49 (td, 2J (HH) 16.5 Hz, | J (HP) + 4J (HP)| 6.4
2
Hz, 2 H, CH2), 6.68-8.09 (m, 23 H, aromatic). 31P NMR (80.96
2
MHz, CD2Cl2, 220 K): δ 38.2 (d, J (PP) 31.7 Hz, PPh2), 75.9
(t, 2J (PP) 31.7 Hz, PPh3). 13C NMR (75.4 MHz, CD2Cl2): δ
37.5 (tap, J (CP) 15.1 Hz, CH2), 122-136 (11 resonances: 4 s, 2
d, 3 t, 2 m), 163.5 (tap, J (CP) 9.3 Hz), 164.6 (d, 2J (CP) 17.0 Hz,
C
ipso). Anal. Calcd for C51H42F3P3O3SRu + 0.75 CH2Cl2: C,
59.23; H, 4.15. Found: C, 59.20; H, 4.01.
Syn t h esis of (2,6-Bis[(d ip h en ylp h osp h in o)m et h yl]-
p h e n y l )i o d o (t r i p h e n y l p h o s p h i n e )r u t h e n i u m (I I ),
[Ru III{C6H3(CH2P P h 2)2-2,6}(P P h 3)], 4. A solution of 1 (500
mg, 0.57 mmol) in MeOH (10 mL) containing an excess of KI
(3 g, 18 mmol) was heated at reflux for 4 days. After removal
of the solvent in vacuo, the residue was extracted once with
C6H6 (20 mL) followed by separation from insoluble material
by centrifugation. After concentration of the resulting green
solution to 5 mL, a green powder was precipitated by addition
of hexane. The solid was filtered off, washed twice with pen-
tane, and dried in vacuo. Yield: 0.30 g, 64% (mp > 200 °C).
1H NMR (200.13 MHz, CD2Cl2): δ 2.59 (td br, 2J (HH) 16.0 Hz,
Syn t h esis of (2,6-Bis[(d ip h en ylp h osp h in o)m et h yl]-
p h en yl)ch lor o(tr ip h en ylp h osp h in e)r u th en iu m (II), [Ru II-
(26) Baker, P. B.; Saunders, B. C. Tetrahedron 1974, 30, 3303.
(27) J ohnson, E. A. J . Chem. Soc. London 1957, 4155.
2
| J (HP) + 4J (HP)| not resolved, 2 H, CH2), 3.54 (td, 2J (HP)

5694 Organometallics, Vol. 15, No. 26, 1996
Karlen et al.
2
16.0 Hz, | J (HP) + 4J (HP)| 6 Hz, 2 H, CH2), 6.7-8.1 (m, 38 H,
(tap
,
J (CP) 6.5 Hz), 183.5 (s, Cipso). Anal. Calcd for
aromatic). 31P NMR (80.96 MHz, CD2Cl2): δ 36.2 (d, J (PP)
C53H42ClN3P2Ru: C, 69.26; H, 4.57; N, 4.57. Found: C, 68.98;
H, 4.68; N, 4.53.
2
32.4 Hz, PPh2), 77.2 (t, 2J (PP) 32.4 Hz, PPh3). 13C NMR (50.3
MHz, CD2Cl2): δ 40.5 (tap, J (CP) 14.6 Hz, CH2), 122-137 (14
resonances: 2 s, 2 d, 5 t, 5 m), 150.57 (tap J (CP) 8.5 Hz), 177.3
Syn t h esis of (2,6-Bis[(d ip h en ylp h osp h in o)m et h yl]-
p h en yl)(2,2′:6′,2′′-t er p yr id in e)r u t h en iu m (II) Tr iflu o-
r om eth a n esu lfon a te, [Ru II{C6H3(CH2P P h 2)2-2,6}(ter p y)]-
OTf, 6. The air-stable, red complex 6 was synthesized as
described for 5 by heating the triflate complex 3 and 1 equiv
of terpy in MeOH at reflux for 3 h. Yield: 68% (mp 127 °C
(dec)). 1H NMR (200.13 MHz, CD2Cl2): δ 3.95 (tap, 4 H, J (HP)
3 Hz, CH2), 6.4-8.8 (m, 34 H, aromatic). 31P NMR (80.96 MHz,
2
(d, J (CP) 16.0 Hz, Cipso). Anal. Calcd for C50H42ClP3Ru: C,
62.33; H, 4.38. Found: C, 62.38; H, 4.64.
Alter n a tive Syn th esis of 4 Usin g th e Tr ifla te Com p lex
3. A solution of complex 3 in MeOH with an equimolar amount
of KI was stirred for 3 h at room temperature. Workup as
described above afforded 4 in 85% yield.
Syn t h esis of (4-P h en yl-2,6-b is[(d ip h en ylp h osp h in o)-
m eth yl]ph en yl)(2,2′:6′,2′′-ter pyr idin e)r u th en iu m (II) Ch lo-
r id e, [Ru II{C6H2(CH2P P h 2)2-2,6-P h -4}(ter p y)]Cl, 5. A so-
lution of terpy (50 mg, 0.214 mmol) in MeOH (10 mL) was
added to a solution of 2 (200 mg, 0.211 mmol) in MeOH (10
mL). The mixture was heated at reflux for 3 days. During
this time, the color changed slowly from green to red. The
solvent was removed in vacuo, and the residue was extracted
with CH2Cl2 (10 mL). Addition of pentane/Et2O resulted in
precipitation of an air-stable red powder, which was collected,
washed with Et2O, and dried in vacuo. Yield: 0.104 g, 54%
(mp 175 °C). 1H NMR (200.13 MHz, CD2Cl2): δ 3.95 (s, 4 H,
CH2), 6.3-9.1 (m, 38 H, aromatic). 31P NMR (80.96 MHz, CD2-
CD2Cl2): δ 42.7 (s). 13C NMR (75.4 MHz, CD2Cl2): δ 43.4 (tap
,
J (CP) 17.2 Hz, CH2), 124.0 (m), 126.6 (s) 125.3 (s), 128.3 (s),
130.3 (tap, J (CP) 4.1 Hz), 131.2 (s), 131.9 (t, J (CP) 5.3 Hz), 134.5
(t, J (CP) 17.3 Hz), 135.3 (s), 136.6 (s), 148.9 (tap, J (CP) 10.1
Hz), 154.5 (s), 156.5 (s), 159.2 (s), 182.3 (s, Cipso). Anal. Calcd
for C48H38F3N3P2O3SRu: C, 60.26; H, 3.97. Found: C, 59.95;
H, 4.11.
Ack n ow led gm en t . We thank the Swiss National
Science Foundation and CIBA-GEIGY-J ubila¨ums-Stif-
tung for financial support. This work was also sup-
ported in part (P.S.) by the Netherlands Foundation of
Chemical Research (SON) with financial aid from the
Netherlands Organization for Scientific Research (NWO).
We also acknowledge support (P.D.) by the Conselho
Nacional de Desenvolvimento Cient´ıfico e Tecnolo´gico
(CNPq), Brazil.
Cl2): δ 42.5 (s). 13C NMR (50.3 MHz, CD2Cl2): δ 41.73 (tap
J (CP) 16.8 Hz, CH2), 120.25 (tap, J (CP) 8.4 Hz), 123.2 (s), 123.7
(s), 125.92 (s), 126.41 (s), 126.57 (s), 128.33 (tap, J (CP) 4.2 Hz),
128.89 (s), 129.26 (s), 129.92 (tap, J (CP) 5.2 Hz), 132.3 (tap
J (CP) 17.3 Hz), 134.4 (s), 135.0 (s), 135.96 (s), 141.58 (s), 147.45
(tap, J (CP) 9.4 Hz), 152.09 (s), 154.31 (s), 157.53 (s), 182.20
,
,
OM9603833