Bis(iminophosphorano)methane derivatives as precursors of unusual ruthenium carbene complexes: A synthetic and DFT study

Article abstract of DOI:10.1021/om030658w

The synthesis of the novel bis(iminophosphorano)methane derivatives CH ₂[P{=NP(=O)(OR)₂}Ph₂]₂ (R = Ph, Et) and CH₂[P{=NP(=O)(OPh)₂}Ph₂][P{=NP(=O)(OEt) ₂}Ph₂] was reported. The deprotonation reactions of these ligands were also studied. The synthesis of unprecedented ruthenium(II) carbene complexes was discussed. A theoretical study devoted to rationalizing the electronic nature of the carbene moiety in the synthesized ruthenium (II) complex was also described.

Full text of DOI:10.1021/om030658w

Organometallics 2004, 23, 2421-2433
2421
Bis(im in op h osp h or a n o)m eth a n e Der iva tives a s
P r ecu r sor s of Un u su a l Ru th en iu m Ca r ben e Com p lexes:
A Syn th etic a n d DF T Stu d y
Victorio Cadierno,* J osefina D´ıez, J oaqu´ın Garc´ıa-AÄ lvarez, and J ose´ Gimeno*
Departamento de Qu´ımica Orga´nica e Inorga´nica, Instituto Universitario de Qu´ımica
Organometa´lica “Enrique Moles” (Unidad Asociada al CSIC), Facultad de Qu´ımica,
Universidad de Oviedo, E-33071 Oviedo, Spain
Maria J ose´ Calhorda
Departamento de Qu´ımica e Bioquı´mica, Faculdade de Cieˆncias, Universidade de Lisboa,
1749-016 Lisboa, Portugal, and ITQB, Av. da Repu´blica, EAN, Apart. 127,
2781-901 Oeiras, Portugal
Luis F. Veiros*
Centro de Qu´ımica Estrutural, Instituto Superior Te´cnico, 1049-001 Lisboa, Portugal
Received November 12, 2003
The symmetric bis(iminophosphorano)methanes CH2[P{dNP(dO)(OR)2}Ph2]2 (R ) Ph (2a ),
Et (2b)) have been obtained by treatment of bis(diphenylphosphino)methane with a 2-fold
excess of phosphorylated azides (RO)2P(dO)N3. The asymmetric ligand CH2[P{dNP(dO)-
(OPh)2}Ph2][P{dNP(dO)(OEt)2}Ph2] (2c) has been prepared by oxidation of Ph2PCH2P{dNP-
(dO)(OEt)2}Ph2 (1b) with (PhO)2P(dO)N3. Compounds 2a -c can be deprotonated with
sodium hydride, affording the corresponding methanide anions NaCH[P{dNP(dO)(OR)2}-
Ph2]2 (R ) Ph (3a ), Et (3b)) and NaCH[P{dNP(dO)(OPh)2}Ph2][P{dNP(dO)(OEt)2}Ph2] (3c).
Treatment of [{Ru(η6-p-cymene)(µ-Cl)Cl}2] with 3a -c results in the formation of the neutral
complexes [RuCl(η6-p-cymene)(κ2(C,N)-CH[P{dNP(dO)(OR)2}Ph2]2)] (R ) Ph (4a ), Et (4b))
and [RuCl(η6-p-cymene)(κ2(C,N)-CH[P{dNP(dO)(OPh)2}Ph2][P{dNP(dO)(OEt)2}Ph2])] (4c),
via selective κ2(C,N) coordination of the bis(iminophosphorano)methanide anions to ruthe-
nium. The cationic species [Ru(η6-p-cymene)(κ3(C,N,O)-CH[P{dNP(dO)(OR)2}Ph2]2)][SbF6]
(R ) Ph (5a ), Et (5b)) and [Ru(η6-p-cymene)(κ3(C,N,O)-CH[P{dNP(dO)(OPh)2}Ph2][P{dNP-
(dO)(OEt)2}Ph2])][SbF6] (5c/5c′) have been also prepared by reaction of 4a -c with AgSbF6.
Deprotonation of complexes 4a -c or 5a -c′ with NaH generates the unprecedented
ruthenium carbenes [Ru(η6-p-cymene)(κ2(C,N)-C[P{dNP(dO)(OR)2}Ph2]2)] (R ) Ph (6a ), Et
(6b)) and [Ru(η6-p-cymene)(κ2(C,N)-C[P{dNP(dO)(OPh)2}Ph2][P{dNP(dO)(OEt)2}Ph2])] (6c).
The structures of compounds 2a , 5a , and 6a have been confirmed by X-ray crystallography.
DFT calculations on a model for complexes 6a -c, [Ru(η6-C6H6)(κ2(C,N)-C[P{dNP(dO)-
(OMe)2}Me2]2)], suggest a nucleophilic character for the carbon atom in RudC. In agreement
with this theoretical prediction, protonation of complexes 6a -c with HCl or HBF4 takes
place selectively on the carbenic carbon, regenerating 4a -c or 5a -c′, respectively.
In tr od u ction
4 metals,3 samarium,4 and molybdenum,5 while the
bridged species B are known for chromium,6 aluminum,7
The search for novel transition-metal carbene deriva-
tives is one of the most important goals in organome-
tallic chemistry today, due to their widespread appli-
cations in both stoichiometric and catalytic organic
transformations.1 In this respect, Cavell and co-workers
have recently demonstrated that “pincer” (A) or bridged
(B) carbene complexes (see Chart 1) can be readily
obtained from bis(iminophosphorano)methane ligands,
CH2{P(dNSiMe3)R2}2 (R ) Ph, Me, Cy), by deprotona-
tion of the methylenic backbone.2 Until now, structures
of type A have been found in some complexes of group
and group 14 metals.8
As part of our current work dealing with the synthesis
and catalytic activity of ruthenium complexes containing
iminophosphorane ligands,9 we have recently reported
(1) See for example: (a) Doyle, M. P.; Forbes, D. C. Chem. Rev. 1998,
98, 911. (b) Do¨tz, K. H.; Tomuschat, P. Chem. Soc. Rev. 1999, 28, 187.
(c) Zaragoza Do¨rwald, F. In Metal Carbenes in Organic Synthesis;
Wiley-VCH: Weinheim, Germany, 1999. (d) Sierra, M. A. Chem. Rev.
2000, 100, 3591. (e) A special issue on transition-metal carbene
complexes: J . Organomet. Chem. 2001, 617-618, 1-754. (f) Trnka,
T. M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18. (g) Barluenga, J .;
Flo´rez, J .; Fan˜anas, F. J . J . Organomet. Chem. 2001, 624, 5. (h)
Guerchais, V. Eur. J . Inorg. Chem. 2002, 783.
* To whom correspondence should be addressed. E-mail: vcm@
fq.uniovi.es (V.C.); jgh@fq.uniovi.es (J .G.); veiros@ist.utl.pt (L.F.V.).
(2) For an overview see: Cavell, R. G.; Kamalesh Babu, R. P.;
Aparna, K. J . Organomet. Chem. 2001, 617-618, 158.
10.1021/om030658w CCC: $27.50 © 2004 American Chemical Society
Publication on Web 04/15/2004

2422 Organometallics, Vol. 23, No. 10, 2004
Cadierno et al.
Ch a r t 1
Ch a r t 3a
Ch a r t 2
a
R ) R′ ) Ph, Et; R ) Et, R′ ) Ph.
(D and E), and (iii) the synthesis of the unprecedented
ruthenium(II) carbene complexes [Ru(η6-p-cymene)(κ2-
(C,N)-C[P{dNP(dO)(OR)2}Ph2]2)] (R ) Ph, Et) and [Ru-
(η6-p-cymene)(κ2(C,N)-C[P{dNP(dO)(OPh)2}Ph2][P{dNP-
(dO)(OEt)2}Ph2])] (F ). In addition, a theoretical study
(DFT level) devoted to rationalizing the electronic
nature of the carbene moiety in complexes F is de-
scribed.
the preparation of the heterotrifunctional iminophos-
phorane-phosphines Ph2PCH2P{dNP(dO)(OR)2}Ph2
(R ) Ph, Et), via single-stage oxidation of bis(diphen-
ylphosphino)methane (dppm) with the phosphorylated
azides (RO)2P(dO)N3 (R ) Ph, Et).9c As a consequence
of the presence of coordinating phosphoryl substituents,
these ligands have shown a versatile coordination ability
in ruthenium fragments adopting κ1(P) (I), κ2(P,N) (II),
κ2(P,O) (III), and κ3(P,N,O) coordination modes (IV) (see
Chart 2).9c
Continuing with our interest in exploiting the coor-
dination ability and the reactivity of these polydentate
heterofunctional ligands, we report in this paper (see
Chart 3) (i) the synthesis of the novel bis(iminophos-
phorano)methane derivatives CH2[P{dNP(dO)(OR)2}-
Ph2]2 (R ) Ph, Et) and CH2[P{dNP(dO)(OPh)2}Ph2]-
[P{dNP(dO)(OEt)2}Ph2] (C), (ii) deprotonation reactions
of these ligands to afford the corresponding bis(imino-
phosphorano)methanide monoanionic species and their
coordination to (η6-p-cymene)ruthenium(II) fragments
Resu lts a n d Discu ssion
Syn th esis of th e Bis(im in oph osph or an o)m eth an e
Com p ou n d s CH2[P {dNP (dO)(OR)2}P h 2]2 (R ) P h
(2a ), Et (2b)) a n d CH2[P {dNP (dO)(OP h )2}P h 2]-
[P {dNP (dO)(OEt)2}P h 2] (2c). Since the discovery in
1919 of the imination reaction of phosphines with azides
(Staudinger reaction),10 a large number of mono- and
bis(phosphines) have been effectively converted into the
corresponding iminophosphoranes or bis(iminophospho-
ranes), respectively.11 We have found that bis(diphen-
ylphosphino)methane (dppm) reacts with a 2-fold excess
of the readily available phosphoryl azides (RO)2P(dO)-
N3 (R ) Ph, Et), in THF at room temperature, to afford
the novel symmetrical N-phosphoryl bis(iminophospho-
rano)methanes CH2[P{dNP(dO)(OR)2}Ph2]2 (R ) Ph
(2a ), Et (2b); 86 and 81% yields, respectively) (Scheme
1).12 Compounds 2a ,b can be also prepared in similar
yields by treatment of the previously reported imino-
phosphorane-phosphines Ph2PCH2P{dNP(dO)(OR)2}-
Ph2 (R ) Ph (1a ), Et (1b))9c with 1 equiv of the
appropriate phosphoryl azide (Scheme 1). In addition,
the unsymmetrical bis(iminophosphorano)methane CH2-
(3) (a) Cavell, R. G.; Kamalesh Babu, R. P.; Kasani, A.; McDonald,
R. J . Am. Chem. Soc. 1999, 121, 5805. (b) Kamalesh Babu, R. P.;
McDonald, R.; Decker, S. A.; Klobukowski, M.; Cavell, R. G. Organo-
metallics 1999, 18, 4226. (c) Kamalesh Babu, R. P.; McDonald, R.;
Cavell, R. G. Chem. Commun. 2000, 481. (d) Kamalesh Babu, R. P.;
McDonald, R.; Cavell, R. G. Organometallics 2000, 19, 3462. (e)
Aparna, K.; Kamalesh Babu, R. P.; McDonald, R.; Cavell, R. G. Angew.
Chem., Int. Ed. 2001, 40, 4400.
(4) Aparna, K.; Ferguson, M.; Cavell, R. G. J . Am. Chem. Soc. 2000,
122, 726.
(5) Leung, W.-P.; So, C.-W.; Wang, J .-Z.; Mak, T. C. W. Chem.
Commun. 2003, 248.
(6) Kasani, A.; McDonald, R.; Cavell, R. G. Chem. Commun. 1999,
1993.
(10) Staudinger, H.; Meyer, J . Helv. Chim. Acta 1919, 2, 635.
(11) For reviews on the Staudinger reaction see: (a) Gololobov, Y.
G.; Zhamurova, I. N.; Kasukhin, L. F. Tetrahedron 1981, 37, 437. (b)
Gololobov, Y. G.; Kasukhin, L. F. Tetrahedron 1992, 48, 1353. (c)
J ohnson, A. W. In Ylides and Imines of Phosphorus; Wiley: New York,
1999; p 403.
(12) For references dealing with the preparation of symmetrical bis-
(iminophosphorano)methanes CH2{P(dNR)Ph2}2 by oxidation of dppm
with azides RN3 see: (a) Aguiar, A. M.; Aguiar, H. J .; Archibald, T. G.
Tetrahedron Lett. 1966, 27, 3187. (b) Gilyarov, V. A.; Kovtun, V. Y.;
Kabachnik, M. I. Izv. Akad. Nauk SSSR, Ser. Khim. 1967, 5, 1159. (c)
Kovtun, V. Y.; Gilyarov, V. A.; Kabachnik, M. I. Izv. Akad. Nauk SSSR,
Ser. Khim. 1972, 11, 2612. (d) Appel, R.; Ruppert, I. Z. Anorg. Allg.
Chem. 1974, 406, 131. (e) Imhoff, P.; Van Asselt, R.; Elsevier, C. J .;
Vrieze, K.; Goubitz, K.; Van Malssen, K. F.; Stam, C. H. Phosphorus,
Sulfur Silicon Relat. Elem. 1990, 47, 401. (f) Al-Benna, S.; Sarsfield,
M. J .; Thornton-Pett, M.; Ormsby, D. L.; Maddox, P. J .; Bre`s, P.;
Bochmann, M. Dalton 2000, 4247.
(7) (a) Aparna, K.; McDonald, R.; Ferguson, M.; Cavell, R. G.
Organometallics 1999, 18, 4241. (b) Aparna, K.; McDonald, R.; Cavell,
R. G. J . Am. Chem. Soc. 2000, 122, 9314. (c) Cavell, R. G.; Aparna, K.;
Kamalesh Babu, R. P.; Wang, Q. J . Mol. Catal. A 2002, 189, 137.
(8) Leung, W.-P.; Wang, Z.-X.; Li, H.-W.; Mak, T. C. W. Angew.
Chem., Int. Ed. 2001, 40, 2501.
(9) (a) Cadierno, V.; D´ıez, J .; Garc´ıa-Garrido, S. E.; Garc´ıa-Granda,
S.; Gimeno, J . Dalton 2002, 1465. (b) Cadierno, V.; Crochet, P.; Garc´ıa-
AÄ lvarez, J .; Garc´ıa-Garrido, S. E.; Gimeno, J . J . Organomet. Chem.
2002, 663, 32. (c) Cadierno, V.; Crochet, P.; D´ıez, J .; Garc´ıa-AÄ lvarez,
J .; Garc´ıa-Garrido, S. E.; Gimeno, J .; Garc´ıa-Granda, S.; Rodr´ıguez,
M. A. Inorg. Chem. 2003, 42, 3293. (d) Cadierno, V.; Crochet, P.; D´ıez,
J .; Garc´ıa-AÄ lvarez, J .; Garc´ıa-Garrido, S. E.; Garc´ıa-Granda, S.;
Gimeno, J .; Rodr´ıguez, M. A. Dalton 2003, 3240.

Precursors of Unusual Ru Carbene Complexes
Organometallics, Vol. 23, No. 10, 2004 2423
F igu r e 1. ORTEP-type view of the structure of CH2[P{dNP(dO)(OPh)2}Ph2]2 (2a ), showing the crystallographic labeling
scheme. Hydrogen atoms have been omitted for clarity. Thermal ellipsoids are drawn at the 10% probability level. Selected
bond distances (Å) and angles (deg): C(1)-P(2) ) 1.810(3); P(2)-N(1) ) 1.571(2); N(1)-P(1) ) 1.576(2); P(1)-O(1) ) 1.593-
(2); P(1)-O(2) ) 1.588(2); P(1)-O(3) ) 1.458(2); C(1)-P(3) ) 1.814(3); P(3)-N(2) ) 1.573(2); N(2)-P(4) ) 1.586(2); P(4)-
O(4) ) 1.469(2); P(4)-O(5) ) 1.597(2); P(4)-O(6) ) 1.588(2); C(1)-P(2)-N(1) ) 113.87(12); P(2)-N(1)-P(1) ) 131.98(15);
N(1)-P(1)-O(1) ) 102.84(11); N(1)-P(1)-O(2) ) 109.27(12); N(1)-P(1)-O(3) ) 119.66(12); P(2)-C(1)-P(3) ) 121.94-
(14); C(1)-P(3)-N(2) ) 113.34(12); P(3)-N(2)-P(4) ) 130.10(15); N(2)-P(4)-O(4) ) 119.34(12); N(2)-P(4)-O(5) ) 103.82-
(11); N(2)-P(4)-O(6) ) 108.13(12).
2
Sch em e 1
(PhO)2PdO), 4.03 (d, J PP ) 29.8 Hz, (EtO)2PdO), 9.32
(dd, 2J PP ) 29.8 and 16.2 Hz, Ph2PdNP(dO)(OEt)2), and
11.86 (dd, J PP ) 32.9 and 16.2 Hz, Ph2PdNP(dO)-
2
(OPh)2)). The chemical shifts as well as the coupling
constants found can be compared to those described in
the literature for the related iminophosphorane com-
pounds CH2{P(dNR)Ph2}{P(dNR’)Ph2} (R ) R’ or R *
1
R’)12,13 and R3PdNP(dO)(OR’)2.14 (ii) In the H and 13C-
{1H} NMR spectra are found triplet (2a ,b) or doublet
of doublets (2c) signals at ca. 4.6 and 28 ppm for both
proton and carbon resonances, respectively, of the
methylenic PCH2P group, due to the coupling with the
2
phosphorus atom of the Ph2PdN units (ca. J HP ) 15
1
Hz and J CP ) 54 Hz). Moreover, the molecular struc-
ture of 2a has been confirmed by X-ray diffraction. An
ORTEP plot is shown in Figure 1; selected bonding
parameters appear in the caption. As previously ob-
served in other species containing -R2PdNP(dO)(OR’)2
units,9c,14c,d,h the lengths of the formal single and double
PN bonds were found to be very similar (N(1)-P(1) )
1.576(2) Å and N(2)-P(4) ) 1.586(2) Å vs P(2)-N(1) )
1.571(2) Å and P(3)-N(2) ) 1.573(2) Å). This fact is
probably determined by the strong π-acceptor natures
of the phosphoryl groups, which enhance the delocal-
ization of the electronic lone pair on the nitrogen atom
within the P-N-P unit. The PdO (P(1)-O(3) ) 1.458-
(2) Å; P(4)-O(4) ) 1.469(2) Å) and P-O (ca. 1.59 Å) bond
lengths are also typical for these types of com-
pounds.9c,14c,d,h
[P{dNP(dO)(OPh)2}Ph2][P{dNP(dO)(OEt)2}Ph2] (2c)
has been synthesized (75% yield) by oxidation of 1b with
(PhO)2P(dO)N3 in THF at room temperature (Scheme
1).13
Bis(iminophosphorano)methanes 2a -c have been
isolated as air-stable microcrystalline white solids and
characterized by standard spectroscopic techniques (IR
1
and H, 31P{1H}, and 13C{1H} NMR) as well as elemen-
tal analyses (details are given in the Experimental
Section). Relevant spectroscopic features are as follows.
(i) In the 31P{1H} NMR spectra are found two multiplets
for 2a ,b (2a , δ -6.79 ((PhO)2PdO) and 11.48 (Ph2Pd
N); 2b, δ 4.09 ((EtO)2PdO) and 9.72 (Ph2PdN); AA’XX’
spin system) and four well-separated signals with equal
Syn th esis of th e An ion ic Bis(im in op h osp h or a -
n o)m et h a n id e Sp ecies Na CH [P {dNP (dO)(OR )2}-
(14) See for example: (a) Balakrishna, M. S.; Santarsiero, B. D.;
Cavell, R. G. Inorg. Chem. 1994, 33, 3079. (b) Reed, R. W.; Santarsiero,
B.; Cavell, R. G. Inorg. Chem. 1996, 35, 4292. (c) Larre´, C.; Donnadieu,
B.; Caminade, A. M.; Majoral, J . P. Eur. J . Inorg. Chem. 1999, 601.
(d) Balakrishna, M. S.; Abhyankar, R. M.; Walawalker, M. G. Tetra-
hedron Lett. 2001, 42, 2733. (e) Alajar´ın, M.; Lo´pez-Leonardo, C.;
Llamas-Lorente, P. Tetrahedron Lett. 2001, 42, 605. (f) Balakrishna,
M. S.; Teipel, S.; Pinkerton, A. A.; Cavell, R. G. Inorg. Chem. 2001,
40, 1802. (g) Longlet, J . J .; Bodige, S. G.; Watson, W. H.; Nielson, R.
H. Inorg. Chem. 2002, 41, 6507. (h) Maraval, V.; Laurent, R.;
Donnadieu, B.; Caminade, A. M.; Majoral, J . P. Synthesis 2003, 389.
2
relative intensities for 2c (δ -6.42 (d, J PP ) 32.9 Hz,
(13) An exhaustive literature search revealed that the compound
CH2{P(dNPh)Ph2}{P(dNMes)Ph2} (Mes ) 2,4,6-trimethylphenyl) is
the only reported example of a bis(iminophosphorano)methane bearing
dissimilar nitrogen-bound substituents: Hill, M. S.; Hitchcock, P. B.
Dalton 2002, 4694.

2424 Organometallics, Vol. 23, No. 10, 2004
Cadierno et al.
Sch em e 2
phorano)methanide ligands in 4a -c is based on the
NMR spectra, which also clearly show that the forma-
tion of 4a -c proceeds in a diastereoselective manner
(two stereogenic centers are formed, i.e. the ruthenium
atom and the PCHP carbon). Significantly, the 31P{1H}
NMR spectra of 4a ,b are very informative, showing in
both cases the presence of four well-separated signals,
in accordance with the coordination of only one of the
two iminophosphorane groups. This fact discards the
symmetric κ2(N,N) coordination of 3a ,b, for which only
two signals should be expected. Moreover, a strong
downfield shift is observed (∆δ ca. 47 ppm) for one of
the two Ph2PdN resonances (δ 61.40-64.26 ppm) in
comparison to those shown by the free ligands 3a ,b. The
31P{1H} NMR spectrum of complex 4c, containing the
unsymmetrical bis(iminophosphorano)methanide ligand
3c, indicates the selective κ2(C,N) coordination through
the iminophosphorane group attached to the more basic
phosphoryl substituent, i.e. P(dO)(OEt)2 vs P(dO)-
(OPh)2, for which the expected resonance shifting is also
P h 2]2 (R ) P h (3a ), Et (3b)) a n d Na CH[P {dNP (dO)-
(OP h )2}P h 2][P {dNP (dO)(OEt)2}P h 2] (3c). In accord
with the well-known acidic character of the methylenic
backbone in bis(iminophosphorano)methane deriva-
tives,12e,f,15 compounds 2a -c can be easily deprotonated
by NaH, in THF at room temperature, to generate the
corresponding bis(iminophosphorano)methanide species
NaCH[P{dNP(dO)(OR)2}Ph2]2 (R ) Ph (3a ), Et (3b))
and NaCH[P{dNP(dO)(OPh)2}Ph2][P{dNP(dO)(OEt)2}-
Ph2] (3c) in almost quantitative yields (Scheme 2). All
attempts to promote the double deprotonation of 2a -c
with NaH, KH, LDA, MeLi, or nBuLi failed.16
Compounds 3a -c have been isolated as moisture-
sensitive colorless oils and characterized by means of
1H, 31P{1H}, and 13C{1H} NMR spectroscopy (details are
given in the Experimental Section). As a common trend,
when the 31P{1H} NMR spectra of 3a -c are compared
to those of their parent bis(iminophosphorano)methane
precursors 2a -c, slight shifts of the corresponding
resonances are observed: i.e. to low field for the Ph2Pd
N groups (∆δ ca. 5 ppm) and to high field for the
(RO)2PdO units (∆δ ca. -3 ppm). The methine PCHP
proton appears in the 1H NMR spectra as a broad signal
(ν1/2 ) 6-8 Hz) at ca. 2.1 ppm. In contrast, the 13C{1H}
NMR spectra show the expected well-defined triplet
(3a ,b) or doublet of doublets (3c) PCHP resonance (δ
1
observed (see the Experimental Section). H and 13C-
{1H} NMR spectra for 4a -c exhibit signals consistent
with the proposed formulation, the most significant
features being those concerning the methine PCHP
1
group of the ligands: (i) in the H NMR, an unresolved
multiplet at 2.96-3.38 ppm and (ii) in the 13C{1H}
NMR, a well-resolved dddd signal in the range 2.10-
3
4.02 ppm (1J CP ) 93.2-95.8 and 60.0-63.5 Hz; J CP
)
17.6-19.2 and 10.6-12.3 Hz).
The reaction of the neutral complexes [RuCl(η6-p-
cymene)(κ2(C,N)-CH[P{dNP(dO)(OR)2}Ph2]2)] (R ) Ph
(4a ), Et (4b)) with 1 equiv of AgSbF6 generates, via
diastereoselective intramolecular O-coordination of the
free N-phosphoryl iminophosphoranyl fragment, the
cationic derivatives [Ru(η6-p-cymene)(κ3(C,N,O)-CH[P{d
NP(dO)(OR)2}Ph2]2)][SbF6] (R ) Ph (5a ), Et (5b)),
isolated as air-stable microcrystalline solids in 82 and
79% yields, respectively (Scheme 3). In contrast, with
[RuCl(η6-p-cymene)(κ2(C,N)-CH[P{dNP(dO)(OPh)2}-
Ph2][P{dNP(dO)(OEt)2}Ph2])] (4c) as the starting ma-
terial, a nonseparable mixture of the isomers 5c and
5c′ (ca. 2:3 ratio) was obtained (see Scheme 3). The
competitive coordination ability of both arms of the
ligand evidences the hemilabile properties of the N-
phosphoryl iminophosphoranyl fragments -Ph2PdNP-
(dO)(OR)2, in accordance with the behavior described
in related ruthenium(II) complexes.9c,19
1
16.10-19.95) with J CP values in the range of 25.8-34.5
Hz.
Rea ction s of th e Bis(im in op h osp h or a n o)m eth -
a n id e An ion s 3a -c w ith [{Ru (η6-p-cym en e)(µ-Cl)-
Cl}2]. Treatment of the ruthenium(II) dimer [{Ru(η6-
p-cymene)(µ-Cl)Cl}2] with 3a -c in refluxing toluene
results in the stereoselective formation of the neutral
four-membered metallacycles [RuCl(η6-p-cymene)(κ2-
(C,N)-CH[P{dNP(dO)(OR)2}Ph2]2)] (R ) Ph (4a ), Et
(4b)) and [RuCl(η6-p-cymene)(κ2(C,N)-CH[P{dNP(dO)-
(OPh)2}Ph2][P{dNP(dO)(OEt)2}Ph2])] (4c) (68-70%
yield), via selective κ2(C,N) coordination of the bis-
(iminophosphorano)methanide anions to ruthenium
(Scheme 3).
The coordination chemistry of bis(iminophosphorano)-
methanide species [CH{P(dNR’)R2}2]- has been exten-
sively studied over the last few years. Thus, these
anionic ligands can adopt two coordination modes, either
κ2(N,N) or κ2(C,N), forming a six-7a,c,12f,13,17 or four-
membered chelate ring,18 respectively. The assignment
of the κ2(C,N) coordination mode of the bis(iminophos-
Compounds 5a -c′ have been characterized by ele-
mental analyses, conductance measurements (1:1 elec-
(17) (a) Kasani, A.; McDonald, R.; Cavell, R. G. Organometallics
1999, 18, 3775. (b) Ong, C. M.; McKarns, P.; Stephan, D. W. Organo-
metallics 1999, 18, 4197. (c) Gamer, M. T.; Dehnen, S.; Roesky, P. W.
Organometallics 2001, 20, 4230. (d) Aharonian, G.; Feghali, K.;
Gambarotta, S.; Yap, G. P. A. Organometallics 2001, 20, 2616. (e)
Gamer, M. T.; Roesky, P. W. J . Organomet. Chem. 2002, 647, 123. (f)
Wei, P.; Stephan, D. W. Organometallics 2002, 21, 1308. (g) Sarsfield,
M. J .; Helliwell, M.; Collison, D. Chem. Commun. 2002, 2264. (h) Wei,
P.; Stephan, D. W. Organometallics 2003, 22, 601. (i) Evans, D. J .;
Hill, M. S.; Hitchcock, P. B. Dalton 2003, 570. (j) Hill, M. S.; Hitchcock,
P. B. Chem. Commun. 2003, 1758.
(18) (a) Imhoff, P.; Van Asselt, R.; Ernsting, J . M.; Vrieze, K.;
Elsevier, C. J .; Smeets, W. J . J .; Spek, A. L.; Kentgens, A. P. M.
Organometallics 1993, 12, 1523. (b) Imhoff, P.; Gu¨lpen, J . H.; Vrieze,
K.; Smeets, W. J . J .; Spek, A. L.; Elsevier, C. J . Inorg. Chim. Acta 1995,
235, 77. (c) Avis, M. W.; Vrieze, K.; Kooijman, H.; Veldman, N.; Spek,
A. L.; Elsevier, C. J . Inorg. Chem. 1995, 34, 4092. (d) Avis, M. W.;
Vrieze, K.; Ernsting, J . M.; Elsevier, C. J .; Veldman, N.; Spek, A. L.;
Katti, K. V.; Barnes, C. L. Organometallics 1996, 15, 2376. (e)
Aharonian, G.; Gambarotta, S.; Yap, G. P. A. Organometallics 2001,
20, 5008.
(15) (a) Kamalesh Babu, R. P.; Aparna, K.; McDonald, R.; Cavell,
R. G. Inorg. Chem. 2000, 39, 4981. (b) Kamalesh Babu, R. P.; Aparna,
K.; McDonald, R.; Cavell, R. G. Organometallics 2001, 20, 1451. (c)
Gamer, M. T.; Roesky, P. W. Z. Anorg. Allg. Chem. 2001, 627, 877.
(16) The bis(iminophosphorano)methanediide species Li2C{P(dN-
SiMe3)Ph2}2 is known: (a) Kasani, A.; Kamalesh Babu, R. P.; Mc-
Donald, R.; Cavell, R. G. Angew. Chem., Int. Ed. 1999, 38, 1483. (b)
Ong, C. M.; Stephan, D. W. J . Am. Chem. Soc. 1999, 121, 2939.

Precursors of Unusual Ru Carbene Complexes
Organometallics, Vol. 23, No. 10, 2004 2425
Sch em e 3
trolytes), and IR and NMR spectroscopy (see the Ex-
perimental Section for details). In particular, the NMR
spectra support (i) the diastereoselective formation of
5a -c′ and (ii) the κ3(C,N,O) coordination of the ligands,
showing the expected resonance shiftings with respect
to those of their neutral precursors 4a -c. Thus, a
downfield shift (∆δ 8-12 ppm) in the coordinated
(RO)2PdO group phosphorus resonances (the rest of the
signals being almost unaffected), a slight deshielding
of the methine protons (ca. ∆δ 1 ppm), and a shielding
of the PCHP carbon resonances (ca. ∆δ -9 ppm) are
observed. Moreover, the formation of a metallabicyclic
structure and the absolute configurations at the metal
as well as the metalated carbon atom have been
unambiguously determined by a X-ray diffraction study
on complex 5a . As expected, the two enantiomers are
present in the unit cell displaying RRuSC and SRuRC
configurations. A drawing of the molecular structure of
the RRuSC enantiomer is depicted in Figure 2; selected
bond distances and angles are listed in the caption. The
molecule exhibits the usual pseudooctahedral three-
legged piano-stool geometry around the metal with
values of the interligand angles C(11)-Ru-N(1), C(11)-
Ru-O(4), and N(1)-Ru-O(4) and those between the
centroid of the p-cymene ring C* and the legs typical of
a pseudo-octahedron. Remarkably, despite the unsym-
metrical κ3(C,N,O) coordination of the bis(iminophos-
phorane)methanide ligand, the bond distances within
the two -Ph2PdNP(dO)(OPh)2 frameworks are almost
identical (ca. (0.04 Å) and comparable to those found
in the structure of the free ligand CH2[P{dNP(dO)-
(OPh)2}Ph2]2 (2a ) (see Figure 1 and caption). This fact
seems to indicate that electronic delocalization of the
nitrogen lone pair is maintained upon N or O coordina-
tion of the -Ph2PdNP(dO)(OPh)2 units to ruthenium.9c
The Ru-C(11) bond length (2.228(5) Å) shows the
expected value for a ruthenium-carbon single bond.20
F igu r e 2. ORTEP-type view of the structure of the cat-
ion [Ru(η6-p-cymene)(κ3(C,N,O)-CH[P{dNP(dO)(OPh)2}-
Ph2]2)]+ (5a ), showing the crystallographic labeling scheme.
Phenyl groups and hydrogen atoms (except that on the
C(11) carbon) have been omitted for clarity. Thermal
ellipsoids are drawn at the 10% probability level. Selected
bond distances (Å) and angles (deg): Ru-N(1) ) 2.164(4);
Ru-C(11) ) 2.228(5); Ru-O(4) ) 2.154(3); Ru-C* ) 1.679-
(1); C(11)-P(2) ) 1.786(5); P(2)-N(1) ) 1.623(4); N(1)-
P(1) ) 1.610(4); P(1)-O(1) ) 1.593(4); P(1)-O(2) ) 1.584-
(4); P(1)-O(3) ) 1.458(4); C(11)-P(3) ) 1.779(5); P(3)-N(2)
) 1.593(4); N(2)-P(4) ) 1.569(4); P(4)-O(4) ) 1.485(3);
P(4)-O(5) ) 1.596(3); P(4)-O(6) ) 1.575(4); C*-Ru-N(1)
) 134.84(1); C*-Ru-C(11) ) 134.86(1); C*-Ru-O(4) )
125.30(1); C(11)-Ru-N(1) ) 71.59(17); C(11)-Ru-O(4) )
87.44(16); N(1)-Ru-O(4) ) 83.20(14); Ru-C(11)-P(2) )
91.1(2); C(11)-P(2)-N(1) ) 97.7(2); P(2)-N(1)-Ru )
98.13(19); P(2)-N(1)-P(1) ) 128.4(3); Ru-N(1)-P(1) )
138.8(2); N(1)-P(1)-O(1) ) 105.5(2); N(1)-P(1)-O(2) )
104.2(2); N(1)-P(1)-O(3) ) 115.3(2); Ru-C(11)-P(3) )
113.5(3); P(2)-C(11)-P(3) ) 122.4(3); C(11)-P(3)-N(2) )
115.0(2); P(3)-N(2)-P(4) ) 127.7(3); N(2)-P(4)-O(4) )
119.8(2); N(2)-P(4)-O(5) ) 111.2(2); N(2)-P(4)-O(6) )
104.6(2); P(4)-O(4)-Ru ) 127.6(2). C* ) centroid of the
p-cymene ring (C(1), C(2), C(3), C(4), C(5), and C(6)).
Syn th esis of Ru th en iu m (II) Ca r ben e Com p lexes
[R u (η6-p -cym e n e )(K2(C,N )-C[P {dNP (dO)(OR )2}-
P h 2]2)] (R ) P h (6a ), Et (6b)) a n d [Ru (η6-p-cym en e)-
(K2(C,N)-C[P {dNP (dO)(OP h )2}P h 2][P {dNP (dO)(O-
Et)2}P h 2])] (6c). Although the double deprotonation of
the methylenic PCH2P groups in bis(iminophospho-
rano)methane derivatives 2a -c failed, the attachment
of the bis(iminophosphorano)methanide anions 3a -c at
the (η6-arene)ruthenium(II) center enhances the acidity
of the methynic PCHP hydrogen, promoting its depro-
tonation. Thus, the treatment of complexes 4a -c with
NaH, in THF at room temperature, generates the
carbene derivatives [Ru(η6-p-cymene)(κ2(C,N)-C[P{dNP-
(dO)(OR)2}Ph2]2)] (R ) Ph (6a ), Et (6b)) and [Ru(η6-p-
cymene)(κ2(C,N)-C[P{dNP(dO)(OPh)2}Ph2][P{dNP(dO)-
(OEt)2}Ph2])] (6c), isolated as air-stable violet solids in
78-82% yield (Scheme 4). Compounds 6a -c can be also
prepared in similar yields from cationic species 5a -c′
by reaction with NaH in THF at room temperature
(Scheme 4). We note that 6c is selectively formed,
starting from a mixture of the isomers 5c and 5c′. It is
apparent that the formation of the carbenic metallacycle
(19) Variable-temperature 31P{1H} NMR spectra of the mixture 5c/
5c′ (from -30 to 80 °C) in CD3CN show that the ratio is temperature
dependent (ca. 1:2 and 1:1 at -30 and 80 °C, respectively). This is
also in accord with the hemilabile properties of the iminophosphorane
-Ph2PdNP(dO)(OR)2 fragments.
(20) See for example: Seddon, E. A.; Seddon, K. R. In The Chemistry
of Ruthenium; Elsevier: Amsterdam, 1984 and references therein.

2426 Organometallics, Vol. 23, No. 10, 2004
Cadierno et al.
Sch em e 4
in which the iminophosphorane group bearing the more
basic phosphoryl substituent -P(dO)(OEt)2 is coordi-
nated to ruthenium is preferred.
Compounds 6a -c have been characterized by elemen-
tal analyses and IR and NMR (1H, 31P{1H} and 13C{1H})
spectroscopy (see the Experimental Section). Thus, the
deprotonation of the bis(iminophosphorano)methanide
ligands is clearly confirmed by the absence of methinic
PCHP signals in the 1H NMR spectra. Moreover, an
unambiguous characterization of the complex [Ru(η6-
p-cymene)(κ2(C,N)-C[P{dNP(dO)(OPh)2}Ph2]2)] (6a ) by
single-crystal X-ray analysis was undertaken (see Fig-
ure 3 and caption).21 The molecular structure shows a
formally pentacoordinated ruthenium atom, which is
bonded to the p-cymene unit acting as a η6 ligand, the
nitrogen atom of one of the iminophosphorane groups,
and a carbenic PCP carbon. The Ru-C(11) bond length
(1.976(6) Å), which is ca. 0.25 Å shorter than that found
in 5a , is in accord with the multiple-bond character
expected for a metal carbene.22,23 Remarkably, in con-
trast to the classical “pincer” (A) or bridging (B)
coordination modes (see Chart 1), the bis(iminophos-
phorano)methanediide units in 6a -c coordinate via a
single four-membered C,N-chelate ring.24 We also note
that, with the exception of the Ru-C(11) bond length,
distances within the four-membered metallacycle in 6a
are only slightly altered in comparison with the related
F igu r e 3. ORTEP-type view of the structure of [Ru(η6-p-
cymene)(κ2(C,N)-C[P{dNP(dO)(OPh)2}Ph2]2)] (6a ), show-
ing the crystallographic labeling scheme. Phenyl groups
and hydrogen atoms have been omitted for clarity. Thermal
ellipsoids are drawn at the 10% probability level. Selected
bond distances (Å) and angles (deg): Ru-N(1) ) 2.140(5);
Ru-C(11) ) 1.976(6); Ru-C* ) 1.679(1); C(11)-P(2) )
1.717(6); P(2)-N(1) ) 1.628(5); N(1)-P(1) ) 1.597(5); P(1)-
O(1) ) 1.596(4); P(1)-O(2) ) 1.597(4); P(1)-O(3) ) 1.464-
(4); C(11)-P(3) ) 1.738(6); P(3)-N(2) ) 1.587(5); N(2)-
P(4) ) 1.567(5); P(4)-O(4) ) 1.468(4); P(4)-O(5) ) 1.617(5);
P(4)-O(6) ) 1.600(4); C*-Ru-N(1) ) 140.75(1); C*-Ru-
C(11) ) 144.66(1); C(11)-Ru-N(1) ) 74.6(2); Ru-C(11)-
P(2) ) 96.0(3); C(11)-P(2)-N(1) ) 96.6(3); P(2)-N(1)-Ru
) 92.7(2); Ru-N(1)-P(1) ) 131.5(3); P(2)-N(1)-P(1) )
135.7(3); N(1)-P(1)-O(1) ) 108.0(3); N(1)-P(1)-O(2) )
102.4(3); N(1)-P(1)-O(3) ) 117.4(3); Ru-C(11)-P(3) )
128.6(4); P(2)-C(11)-P(3) ) 134.6(4); C(11)-P(3)-N(2) )
116.6(3); P(3)-N(2)-P(4) ) 132.8(3); N(2)-P(4)-O(4) )
121.7(3); N(2)-P(4)-O(5) ) 101.7(3); N(2)-P(4)-O(6) )
109.1(3). C* ) centroid of the p-cymene ring (C(1), C(2),
C(3), C(4), C(5), and C(6)).
(21) The crystals measured contain two molecules in the asymmetric
unit with very similar structural parameters. For brevity, only one
conformer is represented in Figure 3 and only its bond distances and
angles are presented.
(22) Typical RudC double-bond distances fall in the range 1.8-2.0
Å. For instance, bond distances in the well-known Grubbs carbenes
[Ru(dCHR)Cl2(PCy3)2] are 1.851(21) Å (R ) CHdCPh2) and 1.839(3)
Å (R ) p-C6H4Cl): (a) Nguyen, S. T.; Grubbs, R. H.; Ziller, J . W. J .
Am. Chem. Soc. 1993, 115, 9858. (b) Schwab, P.; Grubbs, R. H.; Ziller,
J . W. J . Am. Chem. Soc. 1996, 118, 100.
values in 5a (ca. (0.06 Å), suggesting weak contribution
of its ylidic resonance form (see Chart 4).25
(23) No 13C{1H} NMR signal was observed for the RudC carbon
atoms, despite trials with long acquisition periods.
(24) The related carbene species [Pt(κ2(C,N)-C{P(dNSiMe3)Ph2}2)-
(COD)] has been recently reported: (a) J ones, N. D.; Lin, G.; Gossage,
R. A.; McDonald, R.; Cavell, R. G. Organometallics 2003, 22, 2832. (b)
Lin, G.; J ones, N. D.; Gossage, R. A.; McDonald, R.; Cavell, R. G.
Angew. Chem., Int. Ed. 2003, 42, 4054. The bis(iminophosphorano)-
methaniide fragment [C{P(dNSiMe3)Ph2}2]2- also presents a κ2(C,N)
coordination mode in the bis(germavinylidene) [(Me3SiNdPPh2)2-
CdGefGedC(Ph2PdNSiMe3)2] and the chalcogen-bridged dimers
[(Me3SiNdPPh2)2CdGe(µ-X)]2 (X ) S, Se, Te). See ref 8 and: (c) Leung,
W.-P.; So, C.-W.; Wang, Z.-X.; Wang, J .-Z.; Mak, T. C. W. Organome-
tallics 2003, 22, 4305.
DF T Ca lcu la tion s. To interpret the nature of the
RudC bond in the carbene complexes 6a -c, the elec-
tronic structures of the complexes described in this work
have been investigated by means of B3LYP/DFT calcu-
lations.26,27 The compounds [RuCl(η6-C6H6)(κ2(C,N)-CH-
(25) An important ylidic contribution has been proposed for “pincer”
carbene complexes [MCl2(κ2(C,N)-C{P(dNSiMe3)R2}2)] (M ) Ti, Zr, Hf,
Sm; R ) Ph, Cy).3,4

Precursors of Unusual Ru Carbene Complexes
Organometallics, Vol. 23, No. 10, 2004 2427
F igu r e 4. Optimized geometries (B3LYP) for the complexes [RuCl(η6-C6H6)(κ2(C,N)-CH[P{dNP(dO)(OMe)2}Me2]2)] (4),
[Ru(η6-C6H6)(κ3(C,N,O)-CH[P{dNP(dO)(OMe)2}Me2]2)]+ (5), and [Ru(η6-C6H6)(κ2(C,N)-C[P{dNP(dO)(OMe)2}Me2]2)] (6), with
the more relevant bond distances (Å) around the metal.
Ch a r t 4
to a three-legged piano-stool geometry in which the
ruthenium atom is bonded to a η6-benzene unit, a
chloride anion, and a κ2(C,N)-coordinated bis(imino-
phosphorane)methanide ligand. The resulting four-
membered metallacycle, at first sight similar to that
found in the carbene complex 6, is consistent with the
structure proposed above for complexes 4a -c on the
basis of NMR data.
[P{dNP(dO)(OMe)2}Me2]2)] (4), [Ru(η6-C6H6)(κ3(C,N,O)-
CH[P{dNP(dO)(OMe)2}Me2]2)]+ (5), and [Ru(η6-C6H6)-
(κ2(C,N)-C[P{dNP(dO)(OMe)2}Me2]2)] (6) were used as
models for complexes 4a -c, 5a -c′, and 6a -c, respec-
tively, the p-cymene ligand being replaced by benzene
and the phenyl substituents by methyl groups (see
Computational Details). Figure 4 shows the calculated
structures and the more relevant distances (Tables S1-
S3, giving atomic coordinates, are provided in the
Supporting Information).
The fully optimized geometries obtained for complexes
5 and 6 compare very well with the experimental X-ray
structures of compounds 5a and 6a . In complex 5, the
κ3(C,N,O) coordination of the bis(iminophosphorane)-
methanide ligand results in a three-legged piano-stool
geometry, forming a metallabicyclic structure. In com-
plex 6, the C[P{dNP(dO)(OMe)2}Me2]2 ligand acts as
a bidentate ligand, leading to a four-membered metal-
lacyclic carbene coordinated by C and N, and the overall
geometry corresponds to a two-legged piano stool. The
agreement between the calculated and experimental
structures is also reflected by mean and maximum
absolute deviations of the relevant bond distances
around the metal coordination sphere of 0.03 and 0.06
Å for 5 and 0.04 and 0.07 Å for 6, respectively.
Although both complexes 4 and 5 bear a four-
membered Ru-C-P-N metallacycle, it is interesting
to note that the corresponding Ru-C and Ru-N bond
lengths are different (see Chart 5). Thus, the Ru-C
bond is shorter in complex 4 than that in 5 (2.197 vs
2.223 Å) while the opposite occurs with the Ru-N
distance (2.149 Å vs 2.120 Å). This behavior is supported
on electronic grounds, since the Wiberg indices (WI),
well-known as bond strength indicators,28 decrease from
0.567 (4) to 0.529 (5) for the Ru-C bond, while the
corresponding Ru-N values rise from 0.407 (4) to 0.430
(5). Therefore, in complex 5, the longer and weaker
Ru-C bond is balanced by the shorter and stronger
Ru-N bond. The opposite occurs in complex 4. This
probably arises from the constrained κ3(C,N,O) coordi-
nation of the bis(iminophosphorane)methanide ligand
in 5, where the pivotal Ru-C central bond adapts to
the stereochemical requirements of the metallabicycle
upon forming the Ru-O and Ru-N bonds. In compound
4, there is no Ru-O bond, and the open metallacycle
originates a less constrained structure.
The (η6-benzene)Ru fragments are essentially equiva-
lent in the three complexes 4-6, as shown by the same
mean distance between the metal and the six coordinat-
ing carbon atoms for all species (2.25 Å). The electronic
delocalization along the P-N-P frame of each imino-
phosphorano arm of the ligand, discussed above on the
basis of experimental data, is also a common feature of
the ligands in the three model complexes. In all the
The optimized structure for complex 4 (Figure 4), for
which no X-ray structure could be obtained, corresponds
(26) Parr, R. G.; Yang, W. Density Functional Theory of Atoms and
Molecules; Oxford University Press: New York, 1989.
(27) (a) Becke, A. D. J . Chem. Phys. 1993, 98, 5648. (b) Miehlich,
B.; Savin, A.; Stoll, H.; Preuss, H. Chem. Phys. Lett. 1989, 157, 200.
(c) Lee, C.; Yang, W.; Parr, G. Phys. Rev. B 1988, 37, 785.
(28) Wiberg, K. B. Tetrahedron 1968, 24, 1083.

2428 Organometallics, Vol. 23, No. 10, 2004
Cadierno et al.
Ch a r t 5. Mor e Releva n t Dista n ces a n d Wiber g
In d ices (in Ita lics) for 4-6
F igu r e 5. 3D representation of the HOMO of the complex
[Ru(η6-C6H6)(κ2(C,N)-C[P{dNP(dO)(OMe)2}Me2]2)] (6).
n ) 1, X ) PH3, CO, NCH), where the two Ru-C bonds
within the RuC4 metallacyclopentatriene fragment have
a carbenic nature (dC-C ) 1.94-1.97 Å and WI ) 0.95-
1.07).29 The carbenic character of the RudC(11) bond
in 6 is further confirmed by the nature of the HOMO
(highest occupied molecular orbital), represented in
Figure 5. This orbital is mainly localized on the metal
and the C and N donor atoms of the ligand, and it
describes the π bonding component of the RudC double
bond, with a smaller π* antibonding (N-Ru) contribu-
tion of the nitrogen.
Charges in the carbon atom of the carbenic bond of
model 6 can be calculated from a Natural Population
Analysis (NPA),30 and can also shed light on the
electronic nature of the carbene group in complexes 6a -
c. In order for them to be meaningful, the model carbene
complexes [Ru{dC(OH)2}(PMe3)2(CO)2] (7) and [RuCl2-
(dCH2)(PMe3)2] (8) have been studied for comparison.
The former can be taken as a typical electrophilic
carbene (Fischer type), while the latter (belonging to the
well-known family of Grubbs catalysts)22 represents a
nucleophilic carbene. Some important bond lengths from
their optimized geometries are given in Figure 6. The
RudC bond is much longer in the heteroatomic carbene
7 (dRudC ) 2.026 Å) than in 8 (dRudC ) 1.807 Å). More
interestingly, the charges on the carbenic carbon atoms
reveal a clearly positive carbon in the electrophilic
carbene complex 7 (CC ) 0.386) and an electron-rich
carbon in the nucleophilic carbene 8 (CC ) -0.015).
Although the calculated and experimental RudC bond
distances in the model 6 (1.952 Å) and complex 6a
(1.976(6) Å; see Figure 3) are intermediate between the
two previous calculated values, the charge at the carbon
optimized structures, the maximum difference between
the lengths of the two adjacent N-P bond distances is
0.02 Å, showing from a structural point of view that the
two N-P bonds are similar and suggesting a high
degree of electronic delocalization. This view is further
confirmed, from an electronic point of view, by the
corresponding Wiberg indices, which only deviate up to
0.14 for the same two adjacent N-P bonds, in the three
species 4-6. This discussion is related with the two
resonance forms for complexes 6a -c depicted in Chart
4. The experimental C(11)-P distances obtained in the
X-ray structure of complex 6a suggest a minimum
contribution of the ylidic form (see above), as do the
calculations. In fact, the two C(11)-P bond lengths in
the optimized structure of 6 differ by only 0.02 Å, and
the corresponding Wiberg indices are within 0.08,
indicating that the C-P bonds are essentially equiva-
lent. These data also show that the ylidic PCdP form
is negligible in the description of the bonding around
the carbon.
(29) (a) Calhorda, M. J .; Kirchner, K.; Veiros, L. F. In Perspectives
in Organometallic Chemistry; Screttas, C. G., Steele, B. R., Eds.;
RSC: Cambridge, U.K., 2003; pp 111-119. (b) Ru¨ba, E.; Mereiter, K.;
Schmid, R.; Sapunov, V. N.; Kirchner, K.; Schottenberger, H.; Calhorda,
M. J .; Veiros, L. F. Chem. Eur. J . 2002, 8, 3948. (c) Kirchner, K.;
Calhorda, M. J .; Schmid, R.; Veiros, L. F. J . Am. Chem. Soc. 2003,
125, 11721. (d) Theoretical calculations and reactivity studies on the
In contrast to 4 and 5, complex 6 appears to be
coordinatively unsaturated. As a matter of fact, the
Ru-C bond distance in complex 6 is much shorter (1.952
Å) than in 4 and 5 (2.197 and 2.223 Å, respectively).
This bond is also stronger, according to the Wiberg
indexes, which range from 1.122 in 6 to 0.567 in 4 and
0.529 in 5, thus confirming the carbenic character of
the RudC(11) bond in complex 6. These parameters
(bond lengths and WI values) can be compared to those
calculated, at the same theory level, for the RudC bond
in complexes [Ru(η5-C5H5)(C4H4)X]n+ (n ) 0, X ) Cl;
related species [Ru(η5-C5Me5)(C4H2Ph2)Cl] suggest also
a mixed
Fischer-Schrock-type bis(carbene) structure: Le Paih, J .; Monnier,
F.; De´rien, S.; Dixneuf, P. H.; Clot. E.; Eisenstein, O. J . Am. Chem.
Soc. 2003, 125, 11964.
(30) (a) Carpenter, J . E.; Weinhold, F. J . Mol. Struct. (THEOCHEM)
1988, 169, 41. (b) Carpenter, J . E. Ph.D. Thesis, University of
Wisconsin, Madison, WI, 1987. (c) Foster, J . P.; Weinhold, F. J . Am.
Chem. Soc. 1980, 102, 7211. (d) Reed, A. E.; Weinhold, F. J . Chem.
Phys. 1983, 78, 4066. (e) Reed, A. E.; Weinhold, F. J . Chem. Phys. 1983,
78, 1736. (f) Reed, A. E.; Weinstock, R. B.; Weinhold, F. J . Chem. Phys.
1985, 83, 735. (g) Reed, A. E.; Curtiss, L. A.; Weinhold, F. Chem. Rev.
1988, 88, 899. (h) Weinhold, F.; Carpenter, J . E. In The Structure of
Small Molecules and Ions; Plenum: New York, 1988; p 227.

Precursors of Unusual Ru Carbene Complexes
Organometallics, Vol. 23, No. 10, 2004 2429
moiety is part of a four-membered chelate ligand in a
κ2(C,N) coordination mode (Chart 1; A).3-5,24 DFT stud-
ies shed light on the electronic nature of the carbene
group. Both calculated negative charges and the HOMO
distribution on the carbenic carbon atom reveal its
nucleophilic character. In accord with this, protonation
reactions take place at the carbene moiety. Reactivity
studies aimed at understanding the role of analogous
bis(iminophosphorano)methanes in stabilizing these
atypical carbene moieties are currently in progress.
Exp er im en ta l Section
The manipulations were performed under an atmosphere
of dry nitrogen using vacuum-line and standard Schlenk
techniques. Solvents were dried by standard methods and
distilled under nitrogen before use. All reagents were obtained
from commercial suppliers and used without further purifica-
tion, with the exception of the compounds Ph2PCH2P{dNP-
(dO)(OR)2}Ph2 (R ) Ph (1a ), R ) Et (1b)),9c [{Ru(η6-p-
cymene)(µ-Cl)Cl}2],33 and (EtO)2P(dO)N3,34 which were prepared
by following the methods described in the literature. Infrared
spectra were recorded on a Perkin-Elmer 1720-XFT spectrom-
eter. The conductivities were measured at room temperature,
in ca. 10-3 mol dm-3 acetone solutions, with a J enway PCM3
conductimeter. The C, H, and N analyses were carried out with
a Perkin-Elmer 2400 microanalyzer. NMR spectra were re-
corded on a Bruker DPX300 instrument at 300 MHz (1H),
121.5 MHz (31P), or 75.4 MHz (13C) using SiMe4 or 85% H3-
PO4 as standards. DEPT experiments have been carried out
for all the compounds reported in this paper.
Syn th esis of CH2[P {dNP (dO)(OR)2}P h 2]2 (R ) P h (2a ),
E t (2b)). Met h od A. A solution of bis(diphenylphosphino)-
methane (2 g, 5.2 mmol) in 80 mL of THF was treated, at room
temperature, with the corresponding azide (RO)2P(dO)N3 (10.6
mmol) for 6 h. The solvent was then removed under reduced
pressure to give a colorless oil. A microcrystalline white solid
was obtained by slow diffusion of n-pentane into a saturated
solution of the crude reaction mixture in CH2Cl2 at room
Figu r e 6. Optimized structures (B3LYP) of [Ru{dC(OH)2}-
(PMe3)2(CO)2] (7) and [RuCl2(dCH2)(PMe3)2] (8), with the
more relevant bond distances around the metal.
in 6 is clearly negative (CC ) -1.191), emphasizing the
nucleophilic character of the carbene in complexes 6a -
c. In agreement with this theoretical prediction, we have
experimentally found that protonation of complexes
6a -c with HCl or HBF4 takes place selectively on the
carbenic carbon, regenerating compounds 4a -c and
5a -c′, respectively (see Scheme 4).
Since 13C NMR spectroscopy can also be used to
identify carbenic carbon atoms, the carbon chemical
shifts of 6 have been calculated using the gauge-
independent atomic orbital method (GIAO).31,32 The
most significant features concern the calculated values
of C(11) and the benzene carbon nuclei, which are
located at δ 119 and 90 (mean value) ppm, respectively.
While the latter value falls in the experimental range
measured for the coordinated carbon atoms of the
p-cymene ring in complexes 6a -c (δ 80-99 ppm), the
former value is located close to the chemical shifts
observed experimentally for the resonances arising from
the aromatic carbons (δ 120-137 ppm). This is in
agreement with the fact that no signal could be experi-
mentally observed for the RudC carbon nuclei in 6a -
c,23 which probably is overlapped. Although carbenic
RudC carbon nuclei typically resonate at 250-350 ppm,
the unusual upfield chemical shift calculated for the
RudC carbon in 6 may be explained on the basis of
either the electronic influence of the phosphorus sub-
stituents or the constrained geometry of the four-
membered carbene metallacycle.3a,c
temperature. 2a : yield 86% (3.93 g). Anal. Calcd for C49H42
-
O6P4N2: C, 66.97; H, 4.82; N, 3.19. Found: C, 66.72; H, 4.90;
N, 3.10. IR (KBr, cm-1): ν 503 (s), 576 (s), 616 (m), 689 (s),
764 (m), 802 (m), 936 (s), 1000 (m), 1027 (m), 1072 (m), 1111
(s), 1181 (vs), 1297 (vs), 1439 (s), 1455 (m), 1481 (s), 1598 (s),
2983 (m), 3057 (m). 31P{1H} NMR (CDCl3): δ -6.79 (m,
(PhO)2PdO), 11.48 (m, Ph2PdN) ppm; AA’XX’ spin system. 1H
2
NMR (CDCl3): δ 4.60 (t, 2H, J HP ) 14.9 Hz, PCH2P), 7.04-
7.46 (m, 28H, Ph), 7.71-7.81 (m, 12H, Ph) ppm. 13C{1H} NMR
1
(CDCl3): δ 28.39 (t, J CP ) 54.6 Hz, PCH2P), 120.18-132.22
2
(m, Ph), 151.97 (d, J CP ) 7.1 Hz, Cipso of OPh) ppm. 2b: yield
81% (2.89 g). Anal. Calcd for C33H42O6P4N2: C, 57.73; H, 6.16;
N, 4.08. Found: C, 57.66; H, 5.99; N, 4.00. IR (KBr, cm-1): ν
497 (s), 540 (s), 617 (w), 643 (w), 696 (s), 734 (s), 759 (s), 798
(s), 843 (m), 962 (vs), 1038 (vs), 1109 (s), 1200 (vs), 1311 (vs),
1367 (m), 1391 (m), 1444 (s), 1484 (m), 1590 (w), 1627 (w),
2899 (m), 2944 (m), 2983 (s), 3059 (m). 31P{1H} NMR (CDCl3):
δ 4.09 (m, (EtO)2PdO), 9.72 (m, Ph2PdN) ppm; AA’XX’ spin
In summary, in this work novel ruthenium(II) carbene
complexes have been prepared via the sequential double
deprotonation of bis(iminophosphorano)methane deriva-
tives. These unusual carbenes belong to a scarce series
of transition-metal complexes in which the carbene
3
system. 1H NMR (CDCl3): δ 1.19 (t, 12H, J HH ) 7.1 Hz,
2
OCH2CH3), 3.87 (m, 8H, OCH2CH3), 4.63 (t, 2H, J HP ) 15.1
Hz, PCH2P), 7.29-7.86 (m, 20H, Ph) ppm. 13C{1H} NMR
3
(CDCl3): δ 16.17 (d, J CP ) 7.6 Hz, OCH2CH3), 27.78 (t,
2
1J CP ) 53.3 Hz, PCH2P), 61.41 (d, J CP ) 6.4 Hz, OCH2CH3),
(31) (a) Wolinski, K.; Hilton, J . F.; Pulay, P. J . Am. Chem. Soc. 1990,
112, 8251. (b) Dodds, J . L.; McWeeny, R.; Sadlej, A. J . Mol. Phys. 1980,
41, 1419. (c) Ditchfield, R. Mol. Phys. 1974, 27, 789. (d) McWeeny, R.
Phys. Rev. 1962, 126, 1028. (e) London, F. J . Phys. Radium, Paris 1937,
8, 397.
(32) This method has proved to be successful in determining the
coordination modes of pyrrolyl ligands in Zr and W organometallic
complexes, by comparison with experimental data: (a) Dias, A. R.;
Ferreira, A. P.; Veiros, L. F. Organometallics 2003, 22, 5114. (b)
Ascenso, J . R.; Dias, A. R.; Ferreira, A. P.; Galva˜o, A. C.; Salema, M.
S.; Veiros, L. F. Inorg. Chim. Acta 2003, 356, 249.
128.17-131.89 (m, Ph) ppm.
Meth od B. A solution of the corresponding iminophospho-
rane-phosphine Ph2PCH2P{dNP(dO)(OR)2}Ph2 (1a,b; 5 mmol)
in 80 mL of THF was treated, at room temperature, with the
(33) Bennett, M. A.; Huang, T.-N.; Matheson, T. W.; Smith, A. K.
Inorg. Synth. 1982, 21, 74.
(34) Scott, F. L.; Riordan, R.; Morton, P. D. J . Org. Chem. 1962, 27,
4255.

2430 Organometallics, Vol. 23, No. 10, 2004
Cadierno et al.
appropriate azide (RO)2P(dO)N3 (5.2 mmol) for 4 h. Workup
as described in method A allows the isolation of compounds
2a ,b in 84 and 78% yields, respectively.
hexanes (ca. 50 mL) precipitated an orange solid, which was
filtered, washed with hexanes (3 × 10 mL), and dried in vacuo.
4a : yield 70% (0.394 g). Anal. Calcd for RuC59H55O6P4N2Cl:
C, 61.70; H, 4.83; N, 2.44. Found: C, 61.42; H, 4.78; N, 2.24.
IR (KBr, cm-1): ν 525 (m), 577 (m), 616 (m), 748 (s), 797 (s),
916 (vs), 1025 (s), 1071 (s), 1102 (vs), 1144 (vs), 1195 (vs), 1260
(s), 1436 (s), 1489 (s), 1591 (s), 2961 (w), 3055 (w). 31P{1H}
Syn th esis of CH2[P {dNP (dO)(OP h )2}P h 2][P {dNP (d
O)(OEt)2}P h 2] (2c). A solution of the iminophosphorane-
phosphine Ph2PCH2P{dNP(dO)(OEt)2}Ph2 (1b; 1 g, 1.87
mmol) in 60 mL of THF was treated, at room temperature,
with (PhO)2P(dO)N3 (0.55 g, 2 mmol) for 4 h. The solvent was
then removed under reduced pressure to give a colorless oil.
A microcrystalline white solid was obtained by slow diffusion
of n-pentane into a saturated solution of the crude reaction
mixture in CH2Cl2 at room temperature. Yield: 75% (1.10 g).
Anal. Calcd for C41H42O6P4N2: C, 62.92; H, 5.41; N, 3.58.
Found: C, 62.90; H, 5.71; N, 3.59. IR (KBr, cm-1): ν 505 (s),
616 (w), 690 (s), 772 (m), 797 (s), 920 (s), 1035 (s), 1057 (s),
1108 (s), 1189 (vs), 1271 (vs), 1439 (s), 1481 (s), 1483 (s), 1590
(s), 2897 (m), 2926 (m), 2976 (m), 3057 (m). 31P{1H} NMR
2
NMR ((CD3)2CO): δ -8.59 (d, J PP ) 40.6 Hz, (PhO)2PdO),
-2.15 (dd, 2J PP ) 12.6 Hz, 4J PP ) 7.2 Hz, Ru-NP(dO)(OPh)2),
2
4
21.90 (ddd, J PP ) 40.6 and 4.7 Hz, J PP ) 7.2 Hz, Ph2PdN),
64.26 (dd, 2J PP ) 12.6 and 4.7 Hz, Ru-NdPPh2) ppm. 1H NMR
((CD3)2CO): δ 1.12 (d, 3H, J HH ) 6.8 Hz, CH(CH3)2), 1.38 (d,
3H, J HH ) 7.1 Hz, CH(CH3)2), 2.40 (s, 3H, CH3), 2.85 (m, 1H,
3
3
CH(CH3)2), 3.22 (m, 1H, PCHP), 4.77 and 6.41 (d, 1H each,
3J HH ) 5.7 Hz, CH of p-cymene), 5.79 and 6.04 (d, 1H each,
3J HH ) 6.2 Hz, CH of p-cymene), 6.98-8.58 (m, 40H, Ph) ppm.
1
13C{1H} NMR ((CD3)2CO): δ 4.02 (dddd, J CP ) 93.2 and 62.5
Hz, 3J CP ) 19.2 and 11.4 Hz, PCHP), 18.78 (s, CH3), 22.52 and
22.75 (s, CH(CH3)2), 31.42 (s, CH(CH3)2), 74.38, 82.00, 83.22
and 87.59 (s, CH of p-cymene), 92.17 and 107.76 (s, C of
2
(CDCl3): δ -6.42 (d, J PP ) 32.9 Hz, (PhO)2PdO), 4.03 (d,
2
2J PP ) 29.8 Hz, (EtO)2PdO), 9.32 (dd, J PP ) 29.8 and 16.2
Hz, Ph2PdNP(dO)(OEt)2), 11.86 (dd, 2J PP ) 32.9 and 16.2 Hz,
2
p-cymene), 120.02-136.53 (m, Ph), 152.24 (d, J CP ) 7.8 Hz,
1
Ph2PdNP(dO)(OPh)2) ppm. H NMR (CDCl3): δ 1.20 (t, 6H,
C
ipso of OPh), 153.07 and 153.70 (d, 2J CP ) 7.2 Hz, Cipso of OPh),
3J HH ) 7.1 Hz, OCH2CH3), 3.87 (m, 4H, OCH2CH3), 4.61 (dd,
2H, 2J HP ) 15.2 and 15.2 Hz, PCH2P), 7.06-7.81 (m, 30H, Ph)
2
153.79 (d, J CP ) 6.6 Hz, Cipso of OPh) ppm. 4b: yield 69%
(0.322 g). Anal. Calcd for RuC43H55O6P4N2Cl: C, 54.00; H, 5.80;
N, 2.93. Found: C, 54.12; H, 5.89; N, 3.07. IR (KBr, cm-1): ν
509 (s), 536 (s), 588 (m), 694 (s), 732 (s), 799 (s), 980 (s), 1050
(vs), 1109 (s), 1141 (s), 1202 (s), 1238 (s), 1389 (m), 1437 (s),
1482 (m), 1588 (m), 1591 (s), 1639 (m), 2901 (w), 2976 (w),
3
ppm. 13C{1H} NMR (CDCl3): δ 16.53 (d, J CP ) 7.6 Hz,
OCH2CH3), 28.38 (dd, 1J CP ) 54.2 and 54.2 Hz, PCH2P), 61.83
2
(d, J CP ) 6.4 Hz, OCH2CH3), 120.76-132.68 (m, Ph), 152.64
2
(d, J CP ) 7.6 Hz, Cipso of OPh) ppm.
Syn th esis of Na CH[P {dNP (dO)(OR)2}P h 2]2 (R ) P h
(3a ), Et (3b)) a n d Na CH[P {dNP (dO)(OP h )2}P h 2][P {dNP -
(dO)(OEt)2}P h 2] (3c). A solution of the corresponding bis-
(iminophosphorano)methane 2a -c (1 mmol) in 30 mL of THF
was treated, at room temperature, with NaH (0.24 g, 10 mmol)
for 30 min. The solvent was then evaporated to dryness and
the residue dissolved in diethyl ether (ca. 30 mL). The resulting
suspension was filtered through Kieselguhr and the filtrate
evaporated to dryness, giving 3a -c as colorless oils in almost
quantitative yield. 3a : 31P{1H} NMR (C6D6): δ -8.99 (m,
(PhO)2PdO), 16.29 (m, Ph2PdN) ppm; AA’XX’ spin system. 1H
NMR (C6D6): δ 2.29 (broad, 1H, PCHP), 6.81-7.81 (m, 40H,
3053 (w). 31P{1H} NMR (C6D6): δ -1.75 (d, J PP ) 37.2 Hz,
(EtO)2PdO), 7.47 (dd, J PP ) 12.6 Hz, J PP ) 6.3 Hz, Ru-NP-
2
2
4
2
4
(dO)(OEt)2), 17.80 (ddd, J PP ) 37.2 and 2.7 Hz, J PP ) 6.3
Hz, Ph2PdN), 61.40 (dd, 2J PP ) 12.6 and 2.7 Hz, Ru-NdPPh2)
1
3
ppm. H NMR (C6D6): δ 0.87 and 1.19 (t, 3H each, J HH ) 6.8
Hz, OCH2CH3), 1.03 (d, 3H, 3J HH ) 6.9 Hz, CH(CH3)2), 1.12 (t,
3H, J HH ) 7.3 Hz, OCH2CH3), 1.15 (d, 3H, J HH ) 6.8 Hz,
CH(CH3)2), 1.20 (t, 3H, 3J HH ) 6.0 Hz, OCH2CH3), 2.34 (s, 3H,
CH3), 3.02 (m, 1H, CH(CH3)2), 3.38 (m, 1H, PCHP), 4.05 (m,
3
3
3
8H, OCH2CH3), 4.62 and 6.59 (d, 1H each, J HH ) 5.3 Hz, CH
3
of p-cymene), 5.66 and 6.09 (d, 1H each, J HH ) 5.9 Hz, CH of
p-cymene), 6.74-8.77 (m, 20H, Ph) ppm. 13C{1H} NMR
1
Ph) ppm. 13C{1H} NMR (C6D6): δ 19.41 (t, J CP ) 25.8 Hz,
1
3
(C6D6): δ 2.10 (dddd, J CP ) 95.8 and 60.0 Hz, J CP ) 18.6
and 10.6 Hz, PCHP), 16.17 and 16.67 (d, J CP ) 7.8 Hz,
PCHP), 121.75-132.55 (m, Ph), 153.46 (d, 2J CP ) 11.7 Hz, Cipso
of OPh) ppm. 3b: 31P{1H} NMR (C6D6): δ 1.33 (m, (EtO)2Pd
O), 14.47 (m, Ph2PdN) ppm; AA’XX’ spin system. 1H NMR
(C6D6): δ 1.11 (t, 12H, 3J HH ) 6.9 Hz, OCH2CH3), 2.02 (broad,
1H, PCHP), 3.87 (m, 8H, OCH2CH3), 7.15-8.36 (m, 20H, Ph)
3
3
OCH2CH3), 16.57 (d, J CP ) 6.6 Hz, OCH2CH3), 16.91 (d,
3J CP ) 8.0 Hz, OCH2CH3), 18.59 (s, CH3), 22.06 and 22.85 (s,
CH(CH3)2), 31.02 (s, CH(CH3)2), 61.18, 61.39, 61.82, and 62.48
2
(d, J CP ) 5.4 Hz, OCH2CH3), 73.56, 80.16, 83.68, and 87.77
3
ppm. 13C{1H} NMR (C6D6): δ 17.27 (d, J CP ) 8.0 Hz,
(s, CH of p-cymene), 90.28 and 108.66 (s, C of p-cymene),
127.56-137.90 (m, Ph) ppm. 4c: yield 68% (0.351 g). Anal.
Calcd for RuC51H55O6P4N2Cl: C, 58.21; H, 5.27; N, 2.66.
Found: C, 58.02; H, 5.18; N, 2.39. IR (KBr, cm-1): ν 500 (s),
577 (s), 652 (s), 689 (s), 745 (vs), 799 (s), 914 (vs), 1026 (vs),
1108 (s), 1160 (vs), 1198 (vs), 1239 (s), 1285 (s), 1388 (m), 1436
(s), 1488 (s), 1590 (s), 2960 (w), 3054 (w). 31P{1H} NMR ((CD3)2-
1
2
OCH2CH3), 19.95 (t, J CP ) 34.5 Hz, PCHP), 61.68 (d, J CP
)
4.8 Hz, OCH2CH3), 128.38-141.39 (m, Ph) ppm. 3c: 31P{1H}
NMR (C6D6): δ -9.24 (d, J PP ) 22.0 Hz, (PhO)2PdO), 2.07
2
2
2
(d, J PP ) 14.7 Hz, (EtO)2PdO), 14.76 (dd, J PP ) 24.4 and
14.7 Hz, Ph2PdNP(dO)(OEt)2), 16.25 (dd, 2J PP ) 24.4 and 22.0
Hz, Ph2PdNP(dO)(OPh)2) ppm. 1H NMR (C6D6): δ 0.97 (t, 6H,
3J HH ) 6.9 Hz, OCH2CH3), 2.16 (broad, 1H, PCHP), 3.89 (m,
4H, OCH2CH3), 6.78-8.02 (m, 30H, Ph) ppm. 13C{1H} NMR
2
CO): δ -8.38 (d, J PP ) 39.9 Hz, (PhO)2PdO), 8.02 (dd,
2J PP ) 12.7 Hz, 4J PP ) 5.9 Hz, Ru-NP(dO)(OEt)2), 22.47 (ddd,
3
(C6D6): δ 14.85 (d, J CP ) 8.0 Hz, OCH2CH3), 16.10 (dd,
4
2J PP ) 39.9 and 4.2 Hz, J PP ) 5.9 Hz, Ph2PdN), 63.71 (dd,
1J CP ) 34.4 and 34.4 Hz, PCHP), 60.04 (d, 2J CP ) 6.3 Hz, OCH2-
CH3), 119.71-137.37 (m, Ph), 152.03 (d, 2J CP ) 8.0 Hz, Cipso of
OPh) ppm. Compounds 3a -c were too sensitive to moisture
to give satisfactory elemental analyses.
1
2J PP ) 12.7 and 4.2 Hz, Ru-NdPPh2) ppm. H NMR ((CD3)2-
3
CO): δ 0.98 (t, 3H, J HH ) 6.9 Hz, OCH2CH3), 1.03 (d, 3H,
3
3J HH ) 6.7 Hz, CH(CH3)2), 1.17 (t, 3H, J HH ) 7.0 Hz,
OCH2CH3), 1.24 (d, 3H, 3J HH ) 6.8 Hz, CH(CH3)2), 2.34 (s, 3H,
CH3), 2.80 (m, 1H, CH(CH3)2), 2.96 (m, 1H, PCHP), 3.91 (m,
Syn th esis of [Ru Cl(η6-p-cym en e)(K2(C,N)-CH[P {dNP -
(dO)(OR)2}P h 2]2)] (R ) P h (4a ), Et (4b)) a n d [Ru Cl(η6-p-
cym en e)(K2(C,N)-CH[P {dNP (dO)(OP h )2}P h 2][P {dNP (dO)-
(OEt)2}P h 2])] (4c). To a solution of [{Ru(η6-p-cymene)(µ-
Cl)Cl}2] (0.150 g, 0.245 mmol) in 30 mL of toluene was added,
at room temperature, the corresponding bis(iminophosphora-
no)methanide compound 3a -c (0.6 mmol), and the reaction
mixture was refluxed for 1 h. The solvent was then removed
under vacuum, the crude product extracted with diethyl ether
(ca. 50 mL), and the extract filtered. Concentration of the
resulting solution (ca. 5 mL) followed by the addition of
3
4H, OCH2CH3), 4.36 and 6.28 (d, 1H each, J HH ) 5.3 Hz, CH
3
of p-cymene), 5.60 and 5.95 (d, 1H each, J HH ) 5.9 Hz, CH of
p-cymene), 7.10-8.44 (m, 30H, Ph) ppm. 13C{1H} NMR ((CD3)2-
1
3
CO): δ 2.93 (dddd, J CP ) 93.5 and 63.5 Hz, J CP ) 17.6 and
12.3 Hz, PCHP), 16.68 and 16.98 (d, 3J CP ) 8.0 Hz, OCH2CH3),
18.90 (s, CH3), 22.44 and 23.38 (s, CH(CH3)2), 31.86 (s, CH-
2
(CH3)2), 62.50 and 63.00 (d, J CP ) 5.6 Hz, OCH2CH3), 73.70,
81.09, 83.76, and 90.00 (s, CH of p-cymene), 91.05 and 109.71
(s, C of p-cymene), 121.60-135.26 (m, Ph), 154.05 and 154.12
2
(d, J CP ) 7.2 Hz, Cipso of OPh) ppm.

Precursors of Unusual Ru Carbene Complexes
Organometallics, Vol. 23, No. 10, 2004 2431
2
4
Syn th esis of [Ru (η6-p-cym en e)(K3(C,N,O)-CH[P {dNP -
(dO)(OR)2}P h 2]2)][SbF 6] (R ) P h (5a ), Et (5b)) a n d [Ru -
(η6-p-cym en e)(K3(C,N,O)-CH[P {dNP (dO)(OP h )2}P h 2][P -
{dNP (dO)(OEt)2}P h 2])][SbF 6] (5c/5c′). A solution of the
corresponding neutral complex 4a -c (0.25 mmol) in 30 mL of
CH2Cl2 was treated, at room temperature and in the absence
of light, with AgSbF6 (0.086 g, 0.25 mmol) for 1 h. The AgCl
that formed was then filtered off (Kieselguhr) and the resulting
solution concentrated to ca. 2 mL. Addition of diethyl ether
(ca. 50 mL) gave an orange microcrystalline solid which was
filtered, washed with diethyl ether (3 × 20 mL), and vacuum-
dried. Starting from 4c a nonseparable mixture of complexes
5c and 5c′ was obtained in ca. 2:3 ratio. 5a : yield 82% (0.276
g). Anal. Calcd for RuC59H55F6O6P4N2Sb‚2/3CH2Cl2: C, 50.99;
H, 4.04; N, 1.99. Found: C, 50.66; H, 3.76; N, 2.04. Conductiv-
ity (acetone, 20 °C): 110 Ω-1 cm2 mol-1. IR (KBr, cm-1): ν 502
(m), 541 (m), 560 (m), 657 (s), 689 (s), 749 (s), 799 (s), 896 (s),
928 (vs), 1006 (m), 1024 (s), 1133 (vs), 1201 (vs), 1265 (s), 1390
(w), 1435 (s), 1455 (m), 1489 (s), 1590 (s), 2966 (w), 3061 (w).
PdO-Ru), 8.30 (dd, J PP ) 20.2 Hz, J PP ) 3.9 Hz, Ru-NP-
(dO)(OEt)2), 24.90 (dd, 2J PP ) 22.6 Hz, 4J PP ) 3.9 Hz, Ph2PdN),
61.90 (d, J PP ) 20.2 Hz, Ru-NdPPh2) ppm. 1H NMR
(CD2Cl2): δ 1.09 (d, 3H, J HH ) 6.8 Hz, CH(CH3)2), 1.20 (t,
3H, J HH ) 7.4 Hz, OCH2CH3), 1.27 (d, 3H, J HH ) 7.0 Hz,
CH(CH3)2), 1.55 (t, 3H, 3J HH ) 7.0 Hz, OCH2CH3), 1.92 (s, 3H,
CH3), 2.94 (m, 1H, CH(CH3)2), 4.10 (m, 4H, OCH2CH3), 4.44
2
3
3
3
3
(m, 1H, PCHP), 5.13 and 5.38 (d, 1H each, J HH ) 5.7 Hz, CH
3
of p-cymene), 5.16 and 5.27 (d, 1H each, J HH ) 6.0 Hz, CH of
p-cymene), 7.06-8.50 (m, 30H, Ph) ppm. 13C{1H} NMR (CD2-
3
Cl2): δ -6.66 (m, PCHP), 16.45 (d, J CP ) 7.8 Hz, OCH2CH3),
16.62 (d, J CP ) 7.2 Hz, OCH2CH3), 18.37 (s, CH3), 21.82 and
3
22.36 (s, CH(CH3)2), 31.13 (s, CH(CH3)2), 62.76 and 62.98 (d,
2J CP ) 5.4 Hz, OCH2CH3), 77.82, 79.08, 82.88, and 84.84 (s,
CH of p-cymene), 93.78 and 106.74 (s, C of p-cymene), 126.79-
2
135.07 (m, Ph), 152.35 (d, J CP ) 6.6 Hz, Cipso of OPh), 152.45
2
(d, J CP ) 7.8 Hz, Cipso of OPh) ppm. NMR spectroscopic data
for 5c’: 31P{1H} NMR (CD2Cl2): δ -1.21 (dd, J PP ) 23.3 Hz,
2
4J PP ) 5.9 Hz, Ru-NP(dO)(OPh)2), 11.15 (d, J PP ) 20.7 Hz,
2
2
4
2
4
31P{1H} NMR (CD2Cl2): δ -2.70 (dd, J PP ) 20.3 Hz, J PP
)
(EtO)2PdO-Ru), 21.68 (ddd, J PP ) 20.7 and 5.2 Hz, J PP
)
2
4.2 Hz, Ru-NP(dO)(OPh)2), -0.23 (d, 2J PP ) 21.2 Hz, (PhO)2Pd
5.9 Hz, Ph2PdN), 65.65 (dd, J PP ) 23.3 and 5.2 Hz, Ru-Nd
1
3
2
4
PPh2) ppm. H NMR (CD2Cl2): δ 1.01 (d, 3H, J HH ) 6.8 Hz,
O-Ru), 23.51 (ddd, J PP ) 21.2 and 4.0 Hz, J PP ) 4.2 Hz,
CH(CH3)2), 1.23 (t, 3H, 3J HH ) 7.5 Hz, OCH2CH3), 1.27 (d, 3H,
2
Ph2PdN), 63.74 (dd, J PP ) 20.3 and 4.0 Hz, Ru-NdPPh2)
3J HH ) 7.0 Hz, CH(CH3)2), 1.38 (t, 3H, J HH ) 6.9 Hz,
3
ppm. 1H NMR (CD2Cl2): δ 0.97 (d, 3H, J HH ) 6.7 Hz, CH-
3
3
OCH2CH3), 1.90 (s, 3H, CH3), 2.63 (m, 1H, CH(CH3)2), 4.05
(m, 4H, OCH2CH3), 4.62 (m, 1H, PCHP), 5.07 and 5.29 (d, 1H
(CH3)2), 1.21 (d, 3H, J HH ) 7.0 Hz, CH(CH3)2), 1.87 (s, 3H,
CH3), 2.52 (m, 1H, CH(CH3)2), 4.00 (m, 1H, PCHP), 4.86 and
5.07 (d, 1H each, J HH ) 5.3 Hz, CH of p-cymene), 4.94 and
3
3
each, J HH ) 6.0 Hz, CH of p-cymene), 5.15 and 5.24 (d, 1H
each, 3J HH ) 5.2 Hz, CH of p-cymene), 7.06-8.50 (m, 30H, Ph)
ppm. 13C{1H} NMR (CD2Cl2): δ -5.77 (m, PCHP), 16.45 (d,
3J CP ) 7.8 Hz, OCH2CH3), 16.62 (d, 3J CP ) 7.2 Hz, OCH2CH3),
18.27 (s, CH3), 21.56 and 22.76 (s, CH(CH3)2), 31.09 (s, CH-
3
5.39 (d, 1H each, J HH ) 5.8 Hz, CH of p-cymene), 6.88-8.15
(m, 40H, Ph) ppm. 13C{1H} NMR (CD2Cl2): δ -5.58 (dddd,
1J CP ) 60.5 and 60.5 Hz, 3J CP ) 18.4 and 8.6 Hz, PCHP), 18.77
(s, CH3), 21.99 and 22.78 (s, CH(CH3)2), 31.23 (s, CH(CH3)2),
77.61, 79.18, 83.42, and 84.19 (s, CH of p-cymene), 93.97 and
107.97 (s, C of p-cymene), 119.89-135.16 (m, Ph), 151.82 and
2
(CH3)2), 63.07 and 64.76 (d, J CP ) 6.6 Hz, OCH2CH3), 78.13,
79.58, 83.33, and 84.50 (s, CH of p-cymene), 97.16 and 104.18
(s, C of p-cymene), 126.79-135.07 (m, Ph), 152.13 (d, J CP
6.6 Hz, Cipso of OPh), 152.78 (d, J CP ) 7.8 Hz, Cipso of OPh)
2
2
)
151.86 (broad, Cipso of OPh), 152.17 (d, J CP ) 6.0 Hz, Cipso of
OPh), 152.27 (d, J CP ) 7.8 Hz, Cipso of OPh) ppm. 5b: yield
2
2
79% (0.228 g). Anal. Calcd for RuC43H55F6O6P4N2Sb‚3/2CH2-
Cl2: C, 41.63; H, 4.55; N, 2.18. Found: C, 41.35; H, 4.37; N,
2.42. Conductivity (acetone, 20 °C) 113 Ω-1 cm2 mol-1. IR (KBr,
cm-1): ν 500 (m), 531 (s), 553 (s), 586 (s), 657 (vs), 692 (s), 731
(s), 746 (s), 800 (s), 908 (m), 965 (s), 1049 (vs), 1111 (s), 1160
(s), 1240 (s), 1391 (m), 1438 (s), 1489 (m), 1589 (m), 2871 (w),
2906 (m), 2931 (m), 2981 (m), 3060 (w). 31P{1H} NMR (CD2-
ppm.
Syn th esis of [Ru (η6-p-cym en e)(K2(C,N)-C[P {dNP (dO)-
(OR)2}P h 2]2)] (R ) P h (6a), Et (6b)) an d [Ru (η6-p-cym en e)-
(K2(C,N)-C[P {dNP (dO)(OP h )2}P h 2][P {dNP (dO)(OE t )2}-
P h 2])] (6c). Meth od A. A solution of the corresponding neutral
complex 4a -c (0.2 mmol) in 30 mL of THF was treated, at
room temperature, with NaH (0.048 g, 2 mmol) for 3 h. The
solvent was then removed under vacuum, the crude product
extracted with diethyl ether (ca. 50 mL), and the extract
filtered. Concentration of the resulting solution (ca. 2 mL)
followed by the addition of hexanes (ca. 50 mL) precipitated a
violet solid, which was filtered, washed with hexanes (3 × 10
mL), and dried in vacuo. 6a : yield 82% (0.182 g). Anal. Calcd
for RuC59H54O6P4N2: C, 63.72; H, 4.89; N, 2.52. Found: C,
63.66; H, 4.77; N, 2.76. IR (KBr, cm-1): ν 475 (s), 520 (s), 540
(s), 574 (m), 622 (m), 691 (s), 754 (s), 803 (s), 847 (m), 917 (vs),
1025 (s), 1106 (vs), 1184 (vs), 1262 (s), 1343 (m), 1488 (s), 1594
(s), 2853 (w), 2922 (w), 2958 (w), 3055 (w). 31P{1H} NMR
2
4
Cl2): δ 7.47 (dd, J PP ) 18.9 Hz, J PP ) 4.5 Hz, Ru-NP(dO)-
(OEt)2), 10.29 (d, 2J PP ) 20.2 Hz, (EtO)2PdO-Ru), 21.10 (ddd,
2J PP ) 20.2 and 3.0 Hz, J PP ) 4.5 Hz, Ph2PdN), 60.87 (dd,
4
2J PP ) 18.9 and 3.0 Hz, Ru-NdPPh2) ppm. 1H NMR (CD2-
3
Cl2): δ 1.01 (d, 3H, J HH ) 6.8 Hz, CH(CH3)2), 1.08 (t, 3H,
3J HH ) 7.0 Hz, OCH2CH3), 1.16 (t, 3H, J HH ) 6.8 Hz,
3
OCH2CH3), 1.20 (t, 3H, 3J HH ) 6.5 Hz, OCH2CH3), 1.41 (d, 3H,
3J HH ) 6.9 Hz, CH(CH3)2), 1.48 (t, 3H, J HH ) 7.2 Hz,
3
OCH2CH3), 1.81 (s, 3H, CH3), 2.64 (m, 1H, CH(CH3)2), 4.05
(m, 8H, OCH2CH3), 4.25 (m, 1H, PCHP), 4.86 and 5.05 (d, 1H
3
each, J HH ) 5.3 Hz, CH of p-cymene), 4.94 and 4.98 (d, 1H
each, 3J HH ) 5.7 Hz, CH of p-cymene), 6.85-8.15 (m, 20H, Ph)
2
(C6D6): δ -8.55 (d, J PP ) 35.7 Hz, (PhO)2PdO), 0.49 (dd,
1
ppm. 13C{1H} NMR (CD2Cl2): δ -6.56 (dddd, J CP ) 61.3 and
2J PP ) 14.9 Hz, 4J PP ) 9.9 Hz, Ru-NP(dO)(OPh)2), 13.46 (ddd,
3
3
2J PP ) 93.3 and 35.7 Hz, J PP ) 9.9 Hz, Ph2PdN), 67.49 (dd,
4
61.3 Hz, J CP ) 16.3 and 7.6 Hz, PCHP), 16.25 (d, J CP ) 8.2
3
2J PP ) 93.9 and 14.9 Hz, Ru-NdPPh2) ppm. H NMR (C6D6):
1
Hz, OCH2CH3), 16.41 (d, J CP ) 7.6 Hz, OCH2CH3), 16.46 (d,
3J CP ) 7.0 Hz, OCH2CH3), 16.54 (d, 3J CP ) 6.5 Hz, OCH2CH3),
18.10 (s, CH3), 21.89 and 22.00 (s, CH(CH3)2), 30.83 (s, CH-
3
δ 1.15 (d, 6H, J HH ) 6.8 Hz, CH(CH3)2), 1.90 (s, 3H, CH3),
3
2.39 (sept, 1H, J HH ) 6.8 Hz, CH(CH3)2), 5.43 and 5.48 (d,
2
2H each, 3J HH ) 5.7 Hz, CH of p-cymene), 6.77-7.86 (m, 40H,
Ph) ppm. 13C{1H} NMR (C6D6): δ 19.70 (s, CH3), 23.96 (s, CH-
(CH3)2), 30.85 (s, CH(CH3)2), 80.41 and 82.24 (s, CH of
p-cymene), 87.33 and 98.78 (s, C of p-cymene), 120.16-136.97
(CH3)2), 62.65 and 63.58 (d, J CP ) 5.8 Hz, OCH2CH3), 62.90
2
2
(d, J CP ) 5.2 Hz, OCH2CH3), 63.43 (d, J CP ) 6.4 Hz, OCH2-
CH3), 77.40, 78.96, 82.35, and 83.93 (s, CH of p-cymene), 94.37
and 105.04 (s, C of p-cymene), 126.79-135.07 (m, Ph) ppm.
5c/5c′: yield 76% (0.238 g). Anal. Calcd for RuC51H55F6O6P4N2-
Sb‚3/2CH2Cl2: C, 45.69; H, 4.23; N, 2.03. Found: C, 45.50; H,
2
(m, Ph), 153.36 (d, J CP ) 7.2 Hz, Cipso of OPh), 154.85 (d,
2J CP ) 8.2 Hz, Cipso of OPh) ppm; PCP signal not observed.
6b: yield 79% (0.145 g). Anal. Calcd for RuC43H54O6P4N2: C,
56.15; H, 5.92; N, 3.04. Found: C, 55.85; H, 5.87; N, 3.19. IR
(KBr, cm-1): ν 554 (m), 668 (s), 693 (s), 801 (vs), 959 (m), 1028
(vs), 1099 (vs), 1182 (m), 1260 (s), 1435 (s), 1622 (s), 2854 (w),
2924 (w), 2981 (w). 31P{1H} NMR (C6D6): δ 1.10 (d, 2J PP ) 31.1
3.93; N, 2.29. Conductivity (acetone, 20 °C): 106 Ω-1 cm2 mol-1
.
IR (KBr, cm-1): ν 501 (m), 587 (w), 658 (vs), 690 (s), 730 (s),
750 (s), 799 (m), 904 (m), 933 (s), 956 (s), 1026 (vs), 1047 (vs),
1110 (vs), 1141 (vs), 1194 (s), 1260 (s), 1390 (w), 1438 (s), 1489
(s), 1590 (m), 2978 (m), 3061 (w). NMR spectroscopic data for
5c: 31P{1H} NMR (CD2Cl2): δ 0.93 (d, 2J PP ) 22.6 Hz, (PhO)2-
2
4
Hz, (EtO)2PdO), 9.38 (dd, J PP ) 13.3 Hz, J PP ) 8.9 Hz, Ru-

2432 Organometallics, Vol. 23, No. 10, 2004
Cadierno et al.
Ta ble 1. Cr ysta llogr a p h ic Da ta for Com p ou n d s 2a ,
5a , a n d 6a
oscillation method, with 2° oscillation and 200 s (2a ), 40 s (5a ),
or 25 s (6a ) exposure time per frame. The data collection
strategy was calculated with the program Collect.35 Data
reduction and cell refinement were performed with the pro-
grams HKL Denzo and Scalepack.36 Absorption correction was
applied by means of XABS237 (2a and 5a ) or SORTAV38 (6a ).
2a
5a
6a
chem formula
C
49H42O6P4N2 C59H55F6O6P4- C59H54O6P4-
N2RuSb
1348.75
N2Ru
1111.99
-123(2)
1.54180
P1h (No. 2)
11.1659(6)
18.8234(9)
25.721(2)
95.451(3)
94.862(5)
102.152(4)
4
5230.4(6)
1.412
4.017
0.1007
0.0642
fw
T (°C)
878.73
20(2)
All the structures were solved by Patterson interpretation
and phase expansion using DIRDIF.39 Isotropic least-squares
refinement on F2 using SHELXL97 was performed.40 During
the final stages of the refinements, all the positional param-
eters and the anisotropic temperature factors of all the
non-H atoms were refined, with the exception of F atoms of
the SbF6- anion in 5a (this highly disordered group was found
and isotropically refined) and C(5), C(5’), C(9), and C(9’) atoms
in 6a (these atoms were refined isotropically because they
were persistently nonpositive definite). The H atoms were
geometrically located, and their coordinates were refined
riding on their parent atoms. The function minimized was
-153(2)
1.54180
P1h (No. 2)
11.9545(3)
12.7210(3)
18.6112(4)
81.534(2)
84.437(2)
86.828(2)
2
2783.8(1)
1.609
7.760
0.0278
0.0538
wavelength (Å) 1.54180
space group
a, Å
b, Å
c, Å
P1h (No. 2)
9.277(1)
11.643(1)
21.744(1)
86.738(10)
84.131(10)
76.204(10)
2
2267.6(3)
1.287
1.951
0.0740
0.0476
R, deg
â, deg
γ, deg
Z
V, Å3
F
calcd, g cm-3
µ, mm-1
wt function (a)
[∑w(Fo - Fc2)/∑w(Fo2)]1/2, where w ) 1/[σ2(Fo2) + (aP)2]
2
R1a (I > 2σ(I))
(a values are shown in Table 1) with σ2(Fo2) from counting
statistics and P ) (max(Fo2, 0) + 2Fc2)/3. Atomic scattering
factors were taken from ref 41. Geometrical calculations were
made with PARST.42 The crystallographic plots were made
with PLATON.43
wR2a (I > 2σ(I)) 0.1184
0.1372
0.0715
0.1466
0.1772
0.1207
0.2003
R1 (all data)
0.0893
0.1443
wR2 (all data)
R1 ) ∑(|Fo| - |Fc|)/∑|Fo|; wR2 ) {∑[w(Fo2 - Fc2)2]/∑[w(Fo2)2]}1/2
.
a
Com p u ta tion a l Deta ils. All calculations were performed
using the Gaussian 98 software package.44 The B3LYP hybrid
functional was used for the geometry optimizations. That
functional includes a mixture of Hartree-Fock45 exchange with
DFT26 exchange correlation, given by Becke’s three-parameter
functional27a with the Lee, Yang, and Parr correlation func-
tional, which includes both local and nonlocal terms.27b,c The
LanL2DZ basis set46 augmented with an f-polarization func-
tion47 was used for Ru, and the same basis set augmented with
a d-polarization function48 was employed for P and Cl. A
2
4
NP(dO)(OEt)2), 13.63 (ddd, J PP ) 87.8 and 31.1 Hz, J PP
)
8.9 Hz, Ph2PdN), 66.34 (dd, 2J PP ) 87.8 and 13.3 Hz, Ru-Nd
PPh2) ppm. 1H NMR (C6D6): δ 1.23 (t, 6H, J HH ) 7.0 Hz,
3
OCH2CH3), 1.46 (d, 6H, 3J HH ) 6.9 Hz, CH(CH3)2), 1.53 (t, 6H,
3J HH ) 7.2 Hz, OCH2CH3), 1.94 (s, 3H, CH3), 2.68 (sept, 1H,
3J HH ) 6.9 Hz, CH(CH3)2), 4.06 (m, 8H, OCH2CH3), 5.68 and
3
5.71 (d, 2H each, J HH ) 5.7 Hz, CH of p-cymene), 6.88-8.92
(m, 20H, Ph) ppm. 13C{1H} NMR (C6D6): δ 16.38 (d, J CP
)
3
3
7.2 Hz, OCH2CH3), 16.71 (d, J CP ) 7.8 Hz, OCH2CH3), 17.27
(s, CH3), 24.04 (s, CH(CH3)2), 33.22 (s, CH(CH3)2), 61.01 (d,
2J CP ) 4.8 Hz, OCH2CH3), 61.36 (d, 2J CP ) 6.0 Hz, OCH2CH3),
79.53 and 81.38 (s, CH of p-cymene), 86.29 and 97.60 (s, C of
p-cymene), 129.67-136.89 (m, Ph) ppm; PCP signal not
(35) Collect; Nonius BV, Delft, The Netherlands, 1997-2000.
(36) Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307.
(37) Parkin, S.; Moezzi, B.; Hope, H. J . Appl. Crystallogr. 1995, 28,
53.
observed. 6c: yield 78% (0.158 g). Anal. Calcd for RuC51H54
-
(38) Blessing, R. H. Acta Crystallogr., Sect. A 1995, 51, 33.
(39) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
Garc´ıa-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla, C. The
DIRDIF Program System; Technical Report of the Crystallographic
Laboratory; University of Nijmegen, Nijmegen, The Netherlands, 1999.
(40) Sheldrick, G. M. SHELXL97: Program for the Refinement of
Crystal Structures; University of Go¨ttingen, Go¨ttingen, Germany, 1997.
(41) International Tables for X-ray Crystallography; Kynoch Press:
Birmingham, U.K., 1974; Vol. IV. (present distributor: Kluwer Aca-
demic Publishers: Dordrecht, The Netherlands).
O6P4N2: C, 60.29; H, 5.35; N, 2.76. Found: C, 60.15; H, 5.12;
N, 2.98. IR (KBr, cm-1): ν 488 (m), 685 (s), 702 (m), 743 (s),
796 (s), 912 (vs), 955 (m), 1027 (vs), 1109 (vs), 1200 (s), 1258
(s), 1383 (m), 1436 (s), 1484 (s), 1585 (s), 1628 (m), 2854 (w),
2951 (w), 2986 (w), 3057 (w). 31P{1H} NMR (C6D6): δ -8.56
2
2
(d, J PP ) 35.6 Hz, (PhO)2PdO), 9.44 (dd, J PP ) 15.1 Hz,
4J PP ) 9.5 Hz, Ru-NP(dO)(OEt)2), 13.65 (ddd, 2J PP ) 91.1 and
4
2
35.6 Hz, J PP ) 9.5 Hz, Ph2PdN), 66.20 (dd, J PP ) 91.1 and
15.1 Hz, Ru-NdPPh2) ppm. 1H NMR (C6D6): δ 1.29 (t, 6H,
(42) Nardelli, M. Comput. Chem. 1983, 7, 95.
3J HH ) 6.9 Hz, OCH2CH3), 1.56 (d, 6H, J HH ) 6.7 Hz, CH-
3
(43) Spek, A. L. PLATON: A Multipurpose Crystallographic Tool;
University of Utrecht, Utrecht, The Netherlands, 2003.
(44) Frisch, M. J .; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J . R.; Zakrzewski, V. G.; Montgomery, J . A.,
J r.; Stratmann, R. E.; Burant, J . C.; Dapprich, S.; Millam, J . M.;
Daniels, A. D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J .;
Barone, V.; Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo,
C.; Clifford, S.; Ochterski, J .; Petersson, G. A.; Ayala, P. Y.; Cui, Q.;
Morokuma, K.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.;
Foresman, J . B.; Cioslowski, J .; Ortiz, J . V.; Stefanov, B. B.; Liu, G.;
Liashenko, A.; Piskorz, P.; Komaromi, I.; Gomperts, R.; Martin, R. L.;
Fox, D. J .; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
Gonzalez, C.; Challacombe, M.; Gill, P. M. W.; J ohnson, B. G.; Chen,
W.; Wong, M. W.; Andres, J . L.; Head-Gordon, M.; Replogle, E. S.;
Pople, J . A. Gaussian 98, revision A.7; Gaussian, Inc., Pittsburgh, PA,
1998.
(45) Hehre, W. J .; Radom, L.; Schleyer, P. v. R.; Pople, J . A. Ab Initio
Molecular Orbital Theory; Wiley: New York, 1986.
(46) (a) Dunning, T. H., J r.; Hay, P. J . In Modern Theoretical
Chemistry; Schaefer, H. F., III, Ed.; Plenum: New York, 1976; Vol. 3,
p 1. (b) Hay, P. J .; Wadt, W. R. J . Chem. Phys. 1985, 82, 270. (c) Wadt,
W. R.; Hay, P. J . J . Chem. Phys. 1985, 82, 284. (d) Hay, P. J .; Wadt,
W. R. J . Chem. Phys. 1985, 82, 2299.
3
(CH3)2), 2.31 (s, 3H, CH3), 2.81 (sept, 1H, J HH ) 6.7 Hz,
CH(CH3)2), 4.09 (m, 4H, OCH2CH3), 5.78 and 5.81 (broad, 2H
each, CH of p-cymene), 7.18-8.59 (m, 30H, Ph) ppm. 13C{1H}
3
NMR (C6D6): δ 16.42 (d, J CP ) 7.2 Hz, OCH2CH3), 19.83 (s,
CH3), 24.04 (s, CH(CH3)2), 31.72 (s, CH(CH3)2), 61.38 (d,
2J CP ) 6.0 Hz, OCH2CH3), 79.63 and 81.58 (s, CH of p-cymene),
86.24 and 97.61 (s, C of p-cymene), 121.32-136.49 (m, Ph),
2
154.20 (d, J CP ) 7.2 Hz, Cipso of OPh) ppm; PCP signal not
observed.
Meth od B. A solution of the corresponding cationic complex
5a -c′ (0.2 mmol) in 30 mL of THF was treated, at room
temperature, with NaH (0.048 g, 2 mmol) for 2 h. Workup as
described in method A allows the isolation of compounds 6a -c
in 77-85% yield.
X-r a y Cr ysta l Str u ctu r e Deter m in a tion of Com p ou n d s
2a , 5a , a n d 6a . Crystals suitable for X-ray diffraction analysis
were obtained, in all of the cases, by slow diffusion of n-pentane
in a saturated solution of the compound in dichloromethane.
The most relevant crystal and refinement data are collected
in Table 1. Data collections were performed on a Nonius Kappa
CCD single-crystal diffractometer using Cu KR radiation with
the crystal to detector distance fixed at 29 mm, using the
(47) Ehlers, A. W.; Bo¨hme, M.; Dapprich, S.; Gobbi, A.; Ho¨llwarth,
A.; J onas, V.; Ko¨hler, K. F.; Stegmann, R.; Veldkamp, A.; Frenking,
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G. Chem. Phys. Lett. 1993, 208, 237.

Precursors of Unusual Ru Carbene Complexes
Organometallics, Vol. 23, No. 10, 2004 2433
standard 6-31G(d,p) set49 was used for the remaining elements.
All geometries were optimized without symmetry constraints.
In the models used for complexes 4-6, the p-cymene ligand
was replaced by benzene and the phenyl substituents by
methyl groups. A natural population analysis (NPA)30 and the
resulting Wiberg indices28 were used for a detailed study of
the electronic structure and bonding of the optimized species.
NMR shielding tensors were calculated using the gauge-
independent atomic orbital method (GIAO)31 at the Hartree-
Ack n ow led gm en t. This work was supported by the
Ministerio de Ciencia y Tecnolog´ıa (MCyT) of Spain
(Project BQU2000-0227), the Gobierno del Principado
de Asturias (Project PR-01-GE-6), and the EU (COST
Project D24/0014/02). V.C. thanks the MCyT for a
Ramo´n y Cajal contract.
Su p p or tin g In for m a tion Ava ila ble: X-ray crystallo-
graphic files, in CIF format, for the structure determinations
of complexes 2a , 5a , and 6a and tables of atomic coordinates
(Tables S1-S5) and figures (Figures S1-S5), with the struc-
tures and relevant electronic and geometrical parameters, for
all of the optimized species. This material is available free of
charge via the Internet at http://pubs.acs.org.
Fock level using a 3-21G basis set50 augmented with
a
f-polarization function47 for Ru and a 6-311+G(2d,p) set51 for
the remaining elements. The orbital representation was
obtained with the MOLEKEL 4.0 program.52
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