Synthesis, crystal structure and spectroscopic characterization of new neutral and cationic (η6-p-cymene)-ruthenium(II) complexes with phosphine-amide ligands

Article abstract of DOI:10.1016/j.poly.2007.01.033

The dimeric starting material [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂ reacts with the phosphino-amides o-Ph₂P-C₆H₄CO-NH-R [R = ⁱPr (a), Ph (b), 4-MeC₆H₄ (c), 4-FC₆H₄ (d)] to give the mononuclear compounds 1a-d [RuCl(η⁶-p-cymene)(o-Ph₂P-C₆H₄ -CO-NH-R)]Cl. The subsequent reaction of these complexes with KPF₆ produced the cationic species 2a-d [RuCl(η⁶-p-cymene)(o-Ph₂P-C₆H₄ -CO-NH-R)][PF₆] in which phosphino-amides also act as rigid P,O-chelating ligands. The molecular structures of 2b-d were determined crystallographically. Amide deprotonation is achieved when complexes 2a-d were made react with 1 M aqueous solution of KOH, affording the corresponding neutral species 3a-d [RuCl(η⁶-p-cymene)(o-Ph₂P-C₆H₄ -CO-N-R)] in which a P,N-coordination mode is suggested.

Full text of DOI:10.1016/j.poly.2007.01.033

Polyhedron 26 (2007) 2911–2918
www.elsevier.com/locate/poly
Synthesis, crystal structure and spectroscopic characterization of
new neutral and cationic (g6-p-cymene)–ruthenium(II) complexes
with phosphine–amide ligands
a
a
a
b,
b
*
´
´
´
´
´
´
Gregorio Sanchez , Joaquın Garcıa , Juan J. Ayllon , Jose L. Serrano , Luis Garcıa ,
b
a
´ ´
´
Jose Perez , Gregorio Lopez
a
Departamento de Quı´mica Inorga´nica, Universidad de Murcia, 30071 Murcia, Spain
´
Departamento de Ingenierı´a Minera, Geolo´gica y Cartogra´fica, Area de Quı´mica Inorga´nica, 30203 Cartagena, Spain
b
Received 10 January 2007; accepted 26 January 2007
Available online 3 February 2007
Abstract
The dimeric starting material [Ru(g6-p-cymene)(l-Cl)Cl]2 reacts with the phosphino-amides o-Ph2P–C6H4CO–NH–R [R = iPr (a), Ph
(b), 4-MeC6H4 (c), 4-FC6H4 (d)] to give the mononuclear compounds 1a–d [RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–NH–R)]Cl. The sub-
sequent reaction of these complexes with KPF6 produced the cationic species 2a–d [RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–NH–R)][PF6]
in which phosphino-amides also act as rigid P,O-chelating ligands. The molecular structures of 2b–d were determined crystallographi-
cally. Amide deprotonation is achieved when complexes 2a–d were made react with 1 M aqueous solution of KOH, affording the cor-
responding neutral species 3a–d [RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–N–R)] in which a P,N-coordination mode is suggested.
ꢀ 2007 Elsevier Ltd. All rights reserved.
Keywords: Phosphino-amides; Hemilabile ligands; Coordination modes; (g6-p-cymene) complexes; Crystal structures; Ruthenium
1. Introduction
possessing various N,N-dialkyl aromatic amide scaffolds
have shown to be highly effective in Suzuki cross-coupling
reactions [13,14], and 2-diphenylphosphinobenzamido
nickel complexes have found application in ethylene poly-
merization, showing that slight variations in the ligand
frame produce drastic changes in the catalytic behaviour
[15].
On the other hand, half-sandwich ruthenium(II) com-
plexes bearing hemilabile ligands have been studied as effi-
cient catalyst in hydrogen transfer reactions [16–21], and
the hemilabile properties of several P,N- or P,O-donor
ligands have been investigated synthesizing complexes in
which these ligands adopt different coordination modes to
the ruthenium atom [22–26]. No analogous studies concern-
ing the phosphino-amides o-Ph2P–C6H4–CO–NH–R have
been reported and, as far as we are aware, the ligand 1,2-
bis-N[20-(diphenylphosphinobenzoyl)]diaminonaphthalene
and its dimeric p-cymene ruthenium complex is the closest
precedent described to date [26].
Hybrid ligands that contain distinct chemical functions
[1–5], such as soft phosphine and hard (e.g., N or O) donor
atoms, have attracted continuous interest during last years
as a result of their versatile coordination behaviour [6,7]
and its potential hemilability [3–5]. These properties have
been exploited in several ways, as the ‘‘weak-link
approach’’ for the synthesis of supramolecular structures
[8] or the use of some ligands and its complexes in chemical
sensing [9–11] and catalytic processes. It is in this last field
that phosphine–amide ligands have received growing atten-
tion: the asymmetric 1,4-addition reaction of arylboronic
acids with cycloalkenones is catalysed by an amidophos-
phine rhodium(I) complex [12], amide derived phosphines
*
Corresponding author.
E-mail address: jose.serrano@upct.es (J.L. Serrano).
0277-5387/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2007.01.033

2912
G. Sa´nchez et al. / Polyhedron 26 (2007) 2911–2918
We have recently studied the coordination properties of
JHH = 6.0 Hz, 1H, Cy), 5.74 (d, JHH = 6.0 Hz, 1H, Cy),
5.39 (m, 1H, Cy), 5.19 (d, JHH = 6.0 Hz, 1H, Cy), 4.15
these mixed-donor bidentate ligands in their first described
palladium(II) complexes, containing cyclometallated [27]
or pentafluorophenyl co-ligands [28]. As a extension of
our work on o-Ph2P–C6H4–CO–NH–R ligands in this
paper we present the preparation and characterization of
new neutral and cationic (g6-p-cymene)–ruthenium(II)
complexes.
i
(m, 1H, CH, N–iPr), 2.38 (m, 1H, CH, Pr–Cy), 1.88 (s,
3H, Me–Cy), 1.46 (d, JHH = 6.4 Hz, 3H, Me, N–iPr),
1.21 (d, JHH = 6.4 Hz, 3H, Me, N–iPr), 1.15 (d,
i
JHH = 6.6 Hz, 3H, Me, Pr–Cy), 0.54 (d, JHH = 6.4 Hz,
i
3H, Me, Pr–Cy). 31P NMR (300 MHz, CDCl3): d (ppm):
33.8 (s). FAB-MS (positive mode) m/z: 618 (M+ ꢀ Cl),
583 (M+ ꢀ 2Cl).
2. Experimental
[RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–NH–Ph)]Cl (1b):
(71% yield). Anal. Calc. for C35Cl2H34NOPRu: C, 61.1; H,
5.0; N, 2.0. Found: C, 60.9; H, 5.2; N, 2.0%. FT-IR (Nujol
mull cmꢀ1): m(NH) 3405(s); m(CO) 1600(vs). 1H NMR
(300 MHz, CDCl3): d (ppm): 12.99 (s, 1H, NH), 8.61 (m,
1H, P–C6H4–CO–), 7.92–7.31 (m, 15H, 10H PPh2 + 5H
N–Ph), 7.65 (m, 1H, P–C6H4–CO–), 7.21 (m, 1H, P–
C6H4–CO–), 6.69 (m, 1H, P–C6H4–CO–), 5.86 (d,
JHH = 6.6 Hz, 1H, Cy), 5.79 (d, JHH = 6.6 Hz, 1H, Cy),
5.28 (m, 1H, Cy), 4.89 (d, JHH = 4.8 Hz, 1H, Cy), 1.89 (s,
3H, Me–Cy), 1.63 (m, 1H, CH, iPr–Cy), 0.81 (d,
2.1. Methods and materials
C, H, and N analyses were carried out with a Carlo
Erba instrument. IR spectra were recorded on a Per-
kin–Elmer spectrophotometer 16F PC FT-IR, using
Nujol mulls between polyethylene sheets. NMR data
(1H, 31P) were recorded on Bruker Avance 200 and 300
spectrometers. Mass spectrometric analyses were per-
formed on a Fisons VG Autospec double-focusing spec-
trometer, operated in positive mode. Ions were
produced by fast atom bombardment (FAB) with a beam
of 25 keV Cs atoms. The mass spectrometer was operated
with an accelerating voltage of 8 kV and a resolution of
at least 1000. All the solvents were dried by conventional
methods.
i
JHH = 6.0 Hz, 3H, Me, Pr–Cy), ꢀ0.07 (d, JHH = 6.9 Hz,
3H, Me,iPr–Cy). 31P NMR (300 MHz, CDCl3): d (ppm):
33.4 (s). FAB-MS (positive mode) m/z: 652 (M+ꢀCl),
617 (M+ꢀ2Cl).
[RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–NH–C6H4– CH3)]-
Cl (1c): (81% yield). Anal. Calc. for C36Cl2H36NOPRu: C,
61.6; H, 5.2; N, 2.1. Found: C, 61.8; H, 5.3; N, 2.1%. FT-
The diphenylphosphinobenzamides o-Ph2P–C6H4–CO–
NH–R (R = iPr (a), Ph (b), 4-MeC6H4 (c), 4-FC6H4 (d))
were prepared by a reported procedure [28]. The starting
dinuclear dichloro complex [Ru(g6-p-cymene)(l-Cl)Cl]2
was prepared according to a published method [29].
1
IR (Nujol mull cmꢀ1): m(NH) 3402(s); m(CO) 1586(vs). H
NMR (300 MHz, CDCl3): d (ppm): 12.99 (s, 1H, NH),
8.63 (m, 1H, P–C6H4–CO–), 7.90 (m, 2H, N–C6H4–
CH3), 7.65 (m, 1H, P–C6H4–CO–), 7.52–7.39 (m, 10H
PPh2), 7.33 (m, 1H, P–C6H4–CO–), 7.14 (m, 2H, N–
C6H4–CH3), 6.68 (m, 1H, P–C6H4–CO–), 5.85 (d,
JHH = 6.6 Hz, 1H, Cy), 5.79 (d, JHH = 6.6 Hz, 1H, Cy),
5.28 (m, 1H, Cy), 4.89 (d, JHH = 5.1 Hz, 1H, Cy), 2.32
(s, 3H, Me, N–C6H4–CH3), 1.87 (s, 3H, Me–Cy), 1.66
2.2. Synthesis
2.2.1. Preparation of complexes [RuCl(g6-p-cymene)-
(o-Ph2P–C6H4–CO–NH–R)]Cl (R = iPr (1a); R = Ph
(1b); R = 4-MeC6H4 (1c); R = 4-FC6H4 (1d))
i
(m, 1H, CH, Pr–Cy), 0.83 (d, JHH = 6.9 Hz, 3H, Me,
The new complexes were obtained by treating [Ru(g6-p-
cymene)(l-Cl)Cl]2 with previously prepared 2-diphenyl-
phosphine benzamides in molar ratio 1:2, using CH2Cl2
as solvent and according to the following general method.
To a dichloromethane solution (15 mL) of the precursor
(250 mg; 0.40 mmol) was added solid 2-diphenylphosphi-
nebenzamide (0.80 mmol). The resulting solution was stir-
red for 60 min. at room temperature and then
concentrated to half volume under reduced pressure. Addi-
tion of diethyl ether caused precipitation of the new com-
plexes, which were filtered off, air dried and recrystallized
from dicholoromethane–ether.
iPr–Cy), ꢀ0.05 (d, JHH = 6.6 Hz, 3H, Me, Pr–Cy). 31P
i
NMR (300 MHz, CDCl3): d (ppm): 33.4 (s). FAB-MS
(positive mode) m/z: 666 (M+ꢀCl), 631 (M+ꢀ2Cl).
[RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–NH–C6H4–F)]-
Cl (1d): (62% yield). Anal. Calc. for C35Cl2FH33NOPRu:
C, 59.6; H, 4.7; N, 2.0. Found: C, 59.4; H, 4.5; N, 2.3%.
FT-IR (Nujol mull cmꢀ1): m(NH) 3372(s); m(CO)
1
1586(vs). H NMR (300 MHz, CDCl3): d (ppm): 13.25 (s,
1H, NH), 8.69 (m, 1H, P–C6H4–CO–), 7.90 (m, 2H,
N–C6H4–F), 7.67–7.48 (m, 11H, 10H PPh2 + 1H P–
C6H4–CO–), 7.35 (m, 1H, P–C6H4–CO–), 7.06 (m, 2H,
N–C6H4–F), 6.69 (m, 1H, P–C6H4–CO–), 5.87 (d,
JHH = 6.9 Hz, 1H, Cy), 5.79 (d, JHH = 6.6 Hz, 1H, Cy),
5.27 (m, 1H, Cy), 4.92 (d, JHH = 5.4 Hz, 1H, Cy), 1.87 (s,
3H, Me–Cy), 1.67 (m, 1H, CH, iPr–Cy), 0.87 (d,
[RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–NH–iPr)]Cl
(1a): (70% yield). Anal. Calc. for C32Cl2H36NOPRu: C,
58.8; H, 5.5; N, 2.1. Found: C, 59.0; H, 5.7; N, 1.9%.
FT-IR (Nujol mull cmꢀ1): m(NH) 3325(s); m(CO)
i
JHH = 6.9 Hz, 3H, Me, Pr- -Cy), 0.01 (d, JHH = 6.6 Hz,
1
i
1608(vs). H NMR (300 MHz, CDCl3): d (ppm): 10.88 (s,
3H, Me, Pr–Cy). 31P NMR (300 MHz, CDCl3): d (ppm):
1H, NH), 8.52 (m, 1H, P–C6H4–CO–), 7.88–7.44 (m,
11H, 10H, PPh2 + 1H P–C6H4–CO–), 7.24 (m, 1H,
P–C6H4–CO–), 6.51 (m, 1H, P–C6H4–CO–), 5.85 (d,
33.3 (s). 19F NMR (200 MHz, CDCl3): d (ppm): ꢀ114.9
(s). FAB-MS (positive mode) m/z: 670 (M+ꢀCl), 635
(M+ꢀ2Cl).

G. Sa´nchez et al. / Polyhedron 26 (2007) 2911–2918
2913
2.2.2. Preparation of complexes [RuCl(g6-p-cymene)-
(o-Ph2P–C6H4–CO–NH–R)][PF6] (R = iPr (2a); R = Ph
(2b); R = 4-MeC6H4 (2c); R = 4-FC6H4 (2d))
C6H4–CO–), 7.60–7.27 (m, 10H, PPh2), 7.04 (m, 1H, P–
C6H4–CO–), 6.55 (m, 1H, P–C6H4–CO–), 5.68 (d,
JHH = 6.2 Hz, 1H, Cy), 5.46 (d, JHH = 6.2 Hz, 1H, Cy),
5.35 (m, 1H, Cy), 4.99 (d, JHH = 5.6 Hz, 1H, Cy), 4.10
The new complexes were obtained by treating
0.145 mmol of the corresponding complexes [RuCl(g6-p-
(m, 1H, CH, N–iPr), 2.48 (m, 1H, CH, Pr–Cy), 1.89 (s,
i
cymene)(o-Ph2P–C6H4–CO–NH–R)]Cl
(R = iPr
(1a);
3H, Me–Cy), 1.26 (d, JHH = 6.4 Hz, 3H, Me, N–iPr),
1.12 (d, JHH = 6.4 Hz, 3H, Me, N–iPr), 1.03 (d,
JHH = 7.0 Hz, 3H, Me,iPr–Cy), (d, JHH = 7.0 Hz, 3H,
R = Ph (1b); R = 4-MeC6H4 (1c); R = 4-FC6H4 (1d)) in
acetone (20 ml) with stoichiometric KPF6 (0.145 mmol).
After 1/2 h stirring at room temperature, the mixture was
filtered to remove KCl, and the resulting orange solution
then concentrated to half volume under reduced pressure.
Addition of diethyl ether caused precipitation of the new
complexes, which were filtered off, air dried and recrystal-
lized from acetone–ether.
i
Me, Pr–Cy). 31P NMR (300 MHz, CDCl3): d (ppm): 30.2
(s). FAB-MS (positive mode) m/z: 617 (M+), 580
(M+ ꢀ Cl).
[RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–N–Ph)]
(3b):
(52% yield). Anal. Calc. for C35ClH33NOPRu: C, 64.6; H,
5.1; N, 2.1. Found: C, 64.9; H, 5.3; N, 2.2%. FT-IR (Nujol
[RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–NH–iPr)][PF6]
(2a): (85% yield). Anal. Calc. for C32ClF6H36NOP2Ru: C,
50.4; H, 4.8; N, 1.8. Found: C, 50.2; H, 5.0; N, 1.9%.
FT-IR (Nujol mull cmꢀ1): m(NH) 3378(s); m(CO)
1596(vs); m(PF6) 844(s). FAB-MS (positive mode) m/z:
618 (M+ ꢀ PF6), 583 (M+ ꢀ PF6 ꢀ Cl).
mull cmꢀ1): m(CO) 1596(vs). H NMR (300 MHz, CDCl3):
1
d (ppm): 8.46 (m, 1H, P–C6H4–CO–), 8.01-7.36 (m, 11H,
10H PPh2 + 1H P–C6H4–CO), 7.24 (m, 2H, N–Ph), 7.08
(m, 3H, N–Ph), 6.92 (m, 1H, P–C6H4–CO–), 6.66 (m,
1H, P–C6H4–CO–), 5.35 (m, 2H, Cy), 5.16 (m, 1HB, Cy),
4.66 (d, JHH = 5.7 Hz, 1H, Cy), 1.66 (s, 3H, Me–Cy),
[RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–NH–Ph)][PF6]
(2b): (80% yield). Anal. Calc. for C35ClF6H34NOP2Ru: C,
52.7; H, 4.3; N, 1.8. Found: C, 52.9; H, 4.5; N, 1.9%.
FT-IR (Nujol mull cmꢀ1): m(NH) 3352(s); m(CO)
1592(vs); m(PF6) 846(s). FAB-MS (positive mode) m/z:
652 (M+ ꢀ PF6), 617 (M+ ꢀ PF6 ꢀ Cl).
1.60 (m, 1H, CH, Pr–Cy), 0.77 (d, JHH = 6.9 Hz, 3H,
i
i
i
Me, Pr–Cy), 0.23 (d, JHH = 6.9 Hz, 3H, Me, Pr–Cy). 31P
NMR (300 MHz, CDCl3): d (ppm): 28.9 (s). FAB-MS
(positive mode) m/z: 651 (M+), 61 (M+ ꢀ Cl).
[RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–N–C6H4–CH3)]
(3c): (61% yield). Anal. Calc. for C36ClH35NOPRu: C, 65.0;
H, 5.3; N, 2.1. Found: C, 64.8; H, 5.5; N, 2.3%. FT-IR
[RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–NH–C6H4–CH3)]-
[PF6] (2c): (69% yield). Anal. Calc. for C36ClF6H36NO-
P2Ru: C, 53.3; H, 4.5; N, 1.7. Found: C, 53.6; H, 4.7; N,
2.0%. FT-IR (Nujol mull cmꢀ1): m(NH) 3354(s); m(CO)
1594(vs); m(PF6) 847(s). FAB-MS (positive mode) m/z:
666 (M+ ꢀ PF6), 631 (M+ ꢀ PF6 ꢀ Cl).
(Nujol mull cmꢀ1): m(CO) 1572(vs). H NMR (300 MHz,
1
CDCl3): d (ppm): 8.47 (m, 1H, P–C6H4–CO–), 8.00 (m,
2H, P–C6H4–CO–), 7.57–7.37 (m, 10H PPh2), 7.02 (m,
4H, N–C6H4–CH3), 6.66 (m, 1H, P–C6H4–CO–), 5.41 (m,
2H, Cy), 5.20 (m, 1H, Cy), 4.64 (d, JHH = 5.6 Hz, 1H,
Cy), 2.31 (s, 3H, Me N–C6H4–CH3), 2.17 (s, 3H, Me–
[RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–NH–C6H4–F)]-
[PF6] (2d): (67% yield). Anal. Calc. for C35ClF7H33NO-
P2Ru: C, 51.6; H, 4.1; N, 1.7. Found: C, 51.7; H, 4.3; N,
2.0%. FT-IR (Nujol mull cmꢀ1): m(NH) 3354(s); m(CO)
1592(vs); m(PF6) 845(s). FAB-MS (positive mode) m/z:
670 (M+ꢀPF6), 635 (M+ꢀPF6ꢀCl).
i
Cy), 1.60 (m, 1H, CH, Pr–Cy), 0.79 (d, JHH = 7.2 Hz,
i
i
3H, Me, Pr–Cy), 0.21 (d, JHH = 6.8 Hz, 3H, Me, Pr–
Cy). 31P NMR (300 MHz, CDCl3): d (ppm): 29.1 (s).
FAB-MS (positive mode) m/z: 666 (M+), 631 (M+ ꢀ Cl).
[RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–N–C6H4–F)]
(3d): (54% yield). Anal. Calc. for C35ClFH32NOPRu: C,
62.8; H, 4.8; N, 2.1. Found: C, 62.9; H, 4.9; N, 2.2%.
FT-IR (Nujol mull cmꢀ1): m(CO) 1586(vs). 1H NMR
(300 MHz, CDCl3): d (ppm): 8.47 (m, 1H, P–C6H4–CO–),
8.00 (m, 2H, P–C6H4–CO–), 7.60–7.34 (m, 10H, PPh2),
7.14–6.91 (m, 4H, N–C6H4–F), 6.68 (m, 1H, P–C6H4–
CO–), 5.38 (m, 2H, Cy), 5.20 (m, 1H, Cy), 4.71 (d,
2.2.3. Preparation of complexes [RuCl(g6-p-cymene)-
(o-Ph2P–C6H4–CO–N–R)] (R = iPr (3a); R = Ph (3b);
R = 4-MeC6H4 (3c); R = 4-FC6H4 (3d))
The new complexes were obtained by treating
0.145 mmol of the corresponding complexes [RuCl(g6-p-
cymene)(o-Ph2P–C6H4–CO–NH–R)][PF6] (R = iPr (2a);
R = Ph (2b); R = 4-MeC6H4 (2c); R = 4-FC6H4 (2d)) in
acetone (30 ml) with stoichiometric amount of 1 M KOH
aqueous solution. After 1 h stirring at room temperature,
the mixture was concentrated to half volume under reduced
pressure. Addition of diethyl ether caused precipitation of
the new complexes, which were filtered off, washed with
water, air dried and recrystallized from acetone–ether.
i
JHH = 5.8 Hz, 1H, Cy), 1.71 (m, 1H, CH, Pr–Cy), 1.24
i
(s, 3H, Me–Cy), 0.83 (d, JHH = 7.2 Hz, 3H, Me, Pr–Cy),
0.29 (d, JHH = 7.2 Hz, 3H, Me, iPr–Cy). 31P NMR
(200 MHz, CDCl3):
d
(ppm): 29.1 (s). 19F NMR
(300 MHz, CDCl3): d (ppm): ꢀ124.1 (s). FAB-MS (positive
mode): m/z: 670 (M+), 635 (M+ ꢀ Cl).
[RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–N–iPr)]
(3a):
2.3. Crystal structure determination of 2b–2d
(78% yield). Anal. Calc. for C32ClH35NOPRu: C, 62.4; H,
5.6; N, 2.3. Found: C, 62.5; H, 5.8; N, 2.5%. FT-IR (Nujol
Crystals suitable for a diffraction study were prepared
by slow diffusion of hexane into their dichloromethane
solutions. Data collection was performed at ꢀ173 ꢁC on
1
mull cmꢀ1): m(CO) 1586(vs). H NMR (300 MHz, CDCl3):
d (ppm): 8.36 (m, 1H, P–C6H4–CO–), 7.97 (m, 1H, P–

2914
G. Sa´nchez et al. / Polyhedron 26 (2007) 2911–2918
Table 1
Crystal data and structure refinement for compounds 2b–d
2b
2c Æ 1/2CH2Cl2
2d
Empirical formula
Formula weight
Temperature (K)
Wavelength (A)
Crystal system
Space group
C
797.09
100(2)
0.71073
monoclinic
P21/n
35H34ClF6NOP2Ru
C36.5H37Cl2F6NOPRu
853.58
100(2)
0.71073
monoclinic
P21/n
C35H33ClF7NOPRu
784.11
100(2)
0.71073
monoclinic
P21/n
˚
Unit cell dimensions
˚
a (A)
9.6313(4)
9.5651(4)
9.6494(7)
˚
b (A)
24.0527(10)
15.6647(6)
93.0390(10)
24.4322(9)
15.7079(6)
92.8620(10)
24.0892(18)
15.6671(12)
93.0320(10)
˚
c (A)
b (ꢁ)
3
˚
V (A )
3623.8(3)
3666.3(2)
3636.7(5)
Z
4
4
4
Dcalc (Mg mꢀ3
)
1.461
0.654
1616
1.546
0.722
1732
1.432
0.612
1588
Absorption coefficient (mmꢀ1
F(000)
)
Crystal size (mm)
h Range for data collection (ꢁ)
0.29 0.17 · 0.10
1.55–28.23
0.24 · 0.10 · 0.09
1.67–28.23
0.32 · 0.22 · 0.14
1.55–28.07
Index ranges
ꢀ12 6 h 6 12,
ꢀ31 6 k 6 30,
ꢀ20 6 l 6 20
42063
ꢀ12 6 h 6 12,
ꢀ32 6 k 6 31,
ꢀ20 6 l 6 20
42722
ꢀ12 6 h 6 12,
ꢀ31 6 k 6 30,
ꢀ20 6 l 6 20
41122
Reflections collected
Independent reflections [Rint
Refinement method
Data/parameters
Ra, Rwb [I>2r(I)]
Ra, Rwb [all data]
Sc
]
8456 [0.0285]
full-matrix least-squares on F2
8456/424
R1 = 0.0500, wR2 = 0.1625
R1 = 0.0555, wR2 = 0.1675
1.738
8586 [0.0460]
full-matrix least-squares on F2
8586/443
R1 = 0.0496, wR2 = 0.1097
R1 = 0.0603, wR2 = 0.1146
1.117
8395 [0.0282]
full-matrix least-squares on F2
8395/433
R1 = 0.0791, wR2 = 0.2310
R1 = 0.0827, wR2 = 0.2335
1.141
ꢀ3
˚
Maximum, minimum Dq (e A
)
4.849, ꢀ0.603
1.321, ꢀ0.726
6.095, ꢀ1.009
P
P
a
R ¼ jF 0j ꢀ jF Cj= jF 0j.
P
P
2
2
1=2
b
Rw ¼ f ½wðF 20 ꢀ F 2c Þ ꢁ= ½wðF 02Þ ꢁg ; w ¼ 1=r2ðjF 20jÞ.
h
i
1=2
P
2
c
S ¼
½wðF 20 ꢀ F c2Þ ꢁ=ðNobs ꢀ Nparam
Þ
:
a Bruker Smart CCD diffractometer with a nominal crystal
to detector distance of 6.2 cm. Diffraction data were col-
lected based on a x scan run. A total of 2524 frames were
collected at 0.3ꢁ intervals and 10 s per frame. The diffrac-
tion frames were integrated using the SAINT package [30]
and corrected for absorption with SADABS [31].
The structures were solved by direct methods [32] and
refined by full-matrix least-squares techniques using aniso-
tropic thermal parameters for non-H atoms [32] (Table 1).
Hydrogen atoms were introduced in calculated positions
and refined during the last stages of the refinement.
and analytical data are in agreement with the proposed
structures presented in Scheme 1. The appearance of the
m(CO) absorptions lowered by approximately 30 cmꢀ1 with
respect to those of the free ligands gives a first support to
the formation of a PꢂO chelate around the Ru centre
[27,28]. A medium m(NH) vibration, shifted towards higher
wavenumbers than free ligands, is the other remarkable
aspect found in the IR spectra. The FAB mass spectrome-
try displays fragments corresponding to (M+ ꢀ Cl) and
(M+ ꢀ 2Cl). The presence of diphenylphosphine–benzam-
ide ligands is also confirmed by 31P{1H} NMR spectros-
copy, the spectra consisting of singlets around 33 ppm.
This range of chemical shift is typical of a PꢂO coordina-
tion of these ligands to palladium [27] (P-monodentate
around 40 ppm) and is coincidental with the one shown
later for 2a–d ruthenium complexes. Further evidence of
3. Results and discussion
In dichloromethane, the precursor [Ru(g6-p-cymene)(l-
Cl)Cl]2 reacts at room temperature with o-Ph2P–C6H4–
CO–NH–R: (R = iPr (a); R = Ph (b); R = 4-MeC6H4 (c);
R = 4-FC6H4 (d)) (see Section 2 for details) yielding the
orange compounds of general formula [RuCl(g6-p-cym-
ene)(o-Ph2P–C6H4–CO–NH–R)]Cl (R = iPr (1a); R = Ph
(1b); R = 4-MeC6H4 (1c); R = 4-FC6H4 (1d)) in which an
j2-P,O coordination mode for diphenylphosphine–benz-
amide ligands is observed. The characterizing spectroscopic
1
the proposed coordination comes from the H NMR spec-
troscopy. It has been reported that heterobidentate PꢂX
chelates produce chiral metal centers when bound to
arene–ruthenium complexes, and such chirality in p-cym-
ene complexes produces diasterotopic methyls in the iso-
propyl fragment, which serve as detector of the chirality
at the metal [17,33]. Also four different aromatic CH

G. Sa´nchez et al. / Polyhedron 26 (2007) 2911–2918
2915
[Ru(η6-p-cymene)(μ-Cl)Cl]2
CH3
Ph2P
CH2Cl2 r.t.
[Cl]
R
2
+
Ru
Cl
C
N
H
O
2 o-Ph2PC6H4CONHR
CH
CH3
H3C
1a-1d
i
R = Pr (a), Ph (b), 4-MeC6H4 (c), 4-FC6H4 (d)
+2 KPF6
-2 KCl
CH3
CH3
Ph2P
Ph2P
Ru
+2 KOH
-2 KPF6
R
C
C
Ru
Cl
O
N
H
2
[PF6]
2
N
O
-2 H2O
Cl
R
CH
CH3
CH
CH3
H3C
H3C
3a-3d
2a-2d
Scheme 1. Preparation of phosphino-amide derivatives.
groups are usually seen when PꢂX chelates are present,
whereas only two CH’s and one isopropylic methyl reso-
nance are observed if the ligand acts as P-monodentate.
has been reported in the preparation of complexes
[Ru(g6-arene)(j1-P-N*)Cl2]/[Ru(g6-arene)(j2-P-N*)Cl]Cl
[34]. Thus, neutral complexes were obtained in dichloro-
methane while same reactions in methanol afforded the cor-
responding chelate complexes, that also were prepared by
adding small amounts of methanol to solutions of [Ru(g6-
arene)(j1-P-N*)Cl2] in chloroform. A mixture of neutral
and cationic complexes has been reported when the PꢂN
ligand was 2-(diphenylphosphinomethyl)pyridine [35]. In
complexes 1a–d even working in dichloromethane the che-
lating mode of diphenylphosphine–benzamides is preferred.
Such behaviour has been previously found for chiral ruthe-
nium complexes of bidentate bisphosphine monoxide
ligands [Ru(g6-arene)(j1-Ph2PC(R)P(O)Ph2)Cl2]/[Ru(g6-
arene)(j2-Ph2PC(R)P(O)Ph2)Cl]Cl [33], for which an equi-
librium in dichloromethane between the j1-P complexes
and their respective j2-P,O coordination isomers is
reported. The steric bulk in the ligands backbones seems
to drive the chelation, and cationic j2-complexes were
obtained with bulkier ligands, the j1-P complex with the
lighter and mixtures of two coordination isomers for middle
sized. In this previous study, as happens for complexes 1a–
d, conversion of the chloride salts to those with another
counteranion allowed the preparation of crystals suitable
for X-ray diffraction.
1
In our case, the H NMR spectra of complexes 1a–d dis-
play two doublets attributed to diasterotopic methyl
groups in the isopropyl of p-cymene, as well as four CH
aromatic resonances.
It is worth it to mention that no evidence of equilibrium
between coordination isomers [RuCl(g6-p-cymene)(o-Ph2P–
C6H4–CO–NH–R)]Cl and [RuCl2(g6-p-cymene)(o-Ph2P–
C6H4–CO–NH–R)] was observed. The strong chelating
ability of diphenylphosphine–benzamide ligands towards
ruthenium is emphasized by the fact that our attempts to
open the chelate ring with pyridine or bipyridine produced
mixtures of compounds in which the arene had been
removed.
This result is in contrast to our previous studies on the
behaviour of these ligands coordinating palladium(II)
[27], since j1-P binding mode was adopted when chloride
ion was in competition for a position around the metal
center. Only forcing the chloride exit with a silver salt that
provided an appropriate counteranion the chelating coordi-
nation was achieved. Regarding ruthenium(II) arene com-
ˆ
ˆ
plexes with potentially NP or OP hemilabile ligands, most
of the studies reported lately starting from [Ru(g6-p-cym-
ene)(l-Cl)Cl]2 show that direct reaction with this precursor
yields neutral complexes where the ligand is j1P-coordi-
nated to the metal [16–25]. Once again the subsequent treat-
ment with halide abstractors such silver or sodium salts
The reaction in acetone of compounds 1a–d with stoichi-
ometric KPF6 under the mild conditions described in the
experimental section yielded complexes [RuCl(g6-p-cym-
ene)(o-Ph2P–C6H4–CO–NH–R)][PF6] (R = iPr (2a); R =
Ph (2b); R = 4-MeC6H4 (2c); R = 4-FC6H4 (2d)) (Scheme
1). The presence of a P,O-chelate is supported by the
appearance of the m(CO) vibration in the same range
ꢀ
ðmostly BF4ꢀ; BPh4ꢀ; CF3SO3ꢀ; PF6 or SbF6ꢀÞ prefera-
bly in polar solvents provided a route to the chelating
cationic compounds. Strong dependence with the solvent

2916
G. Sa´nchez et al. / Polyhedron 26 (2007) 2911–2918
mentioned above for complexes 1a–d. Other features of IR
spectra are a sharp NH absorption around 3355 cmꢀ1 and
a single band at ca. 845 cmꢀ1 that indicates the presence of
PF6 also detected by 19F and 31P NMR. The rest of NMR
ꢀ
data confirm the proposed formulae and, as expected, are
quite similar to those of precursor complexes in chemical
shift, number and multiplicity of signals and therefore have
not been included in experimental section. Thus, again the
asymmetry of the MLL0L00 three-legged fragment and con-
sequent chirality at Ru centre raised diasterotopic isopro-
pylic methyl groups and differentiated aromatic CH
resonances.
ꢀ
As mentioned above, changing chloride by PF6 made
possible to grow X-ray quality crystals that after diffraction
study have confirmed the structures of 2b–d. Each of them
consisted of a cationic complex [RuCl(g6-p-cymene)-
(o-Ph2P–C6H4–CO–NH–R)]+ (Figs. 1–3, respectively) and
an anion [PF6]ꢀ. While 2c crystallizes with 1/2 molecule
of dichoromethane, 2b and 2d also contain some unrefined
solvent that causes high values of maximum Dq. As can be
inferred from data in Table 1 the three complexes are isomor-
phous. Selected bond lengths and angles listed in Table 2 are
very similar. Moreover, molecular conformation in the
three compounds are similar, the phenyl ring bonded to
the iminic group is oriented towards the isopropyl group
from the g6-arene, with distances from the centroid to
the (Me)2C–H hydrogen atom of 3.081, 2.948 and
Fig. 2. ORTEP diagram of cation complex 2c; thermal ellipsoids are
drawn at the 50% probability level.
˚
3.010 A for complexes 2b, 2c, and 2d, respectively. The
molecules displayed
a pseudooctahedral three-legged
piano-stool geometry around the ruthenium atom with
the arene, the corresponding diphenylphosphine–benzam-
ide ligand and the chloride completing the coordination.
The distortion of the octahedral geometry is shown by
the values of the O(1)–Ru(1)–P(1), O(1)–Ru(1)–Cl(1), and
P(1)–Ru(1)–Cl(1) angles, in the range 82.49(8)–88.02(5)ꢁ
(see Table 2).
Fig. 3. ORTEP diagram of cation complex 2d. Thermal ellipsoids are
drawn at 50% probability.
The angles between the centroid of the arene ring, Ru,
O, P, and Cl atoms are in the 125–133ꢁ range. The Ru–Cl
bond distances fall within the range of reported values
[16,24]. The average Ru–C bond distance is around
˚
2.209 A, whereas the distance between the ruthenium
˚
atom and the centroid of the ring is 1.693 A for the three
compounds. As has been previously reported [17 and ref-
erences therein] a heterogeneous distribution of the Ru–
C(p-cymene) bond distances was observed in the sense
that distances trans to the more strongly donating phos-
phine group are longer that those trans to the chlorine
atoms.
The diphenylphosphine–benzamide ligands are j2-P,O
bonded to ruthenium forming a six-membered metallacycle
that in the three compounds display a 10ꢁ distorted screw–
boat conformation, according to the classification of Allen
and Taylor [36].
Fig. 1. ORTEP diagram of cation complex 2b with the atom numbering
scheme; thermal ellipsoids are drawn at the 50% probability level.

G. Sa´nchez et al. / Polyhedron 26 (2007) 2911–2918
2917
Table 2
Selected distances (A) and angles (ꢁ) of the new complexes
conclusive assertion about the coordination mode. Absence
of arene was observed in the subsequent decomposition
products.
˚
2b 2c
2d
Ru(1)–O(1)
Ru(1)–P(1)
Ru(1)–Cl(1)
Ru(1)–C(1)
Ru(1)–C(2)
Ru(1)–C(3)
Ru(1)–C(4)
Ru(1)–C(5)
2.114(3)
2.3191(10)
2.3930(9)
2.237(4)
2.195(4)
2.169(4)
2.201(4)
2.209(4)
2.243(4)
2.209
2.114(2)
2.3167(8)
2.3926(8)
2.235(3)
2.189(3)
2.171(3)
2.205(3)
2.207(3)
2.240(6)
2.208
2.109(4)
2.3194(15)
2.3936(15)
2.166(6)
2.199(6)
2.232(6)
2.243(6)
2.205(6)
2.206(6)
2.209
4. Conclusion
Twelve new (g6-p-cymene)–ruthenium(II) complexes
with diphenylphosphine–benzamide ligands exhibiting dif-
ferent coordination modes have been prepared and charac-
terized by spectroscopic techniques and single crystal X-ray
diffraction analysis. Stronger j2-P,O chelating ability
towards ruthenium can be attributed to these ligands in
comparison with our previous results dealing with nickel
and palladium. Also if compared with other potentially
hemilabile P,O- or P,N-ligands in its reaction with the
precursor [Ru(g6-p-cymene)(l-Cl)Cl]2, that usually yields
P- monodentate compounds.
Ru(1)–C(6)
Ru(1)–C(average)
Ru(1)–Cent(pꢀcimeno)
O(1)–C(11)
1.693
1.256(5)
1.693
1.250(4)
1.693
1.258(7)
O(1)–Ru(1)–P(1)
O(1)–Ru(1)–Cl(1)
P(1)–Ru(1)–Cl(1)
O(1)–Ru(1)–Centr
P(1)–Ru(1)–Centr
Cl(1)–Ru(1)–Centr
82.49(8)
87.09(8)
87.85(3)
125.73
132.29
126.32
82.56(7)
87.41(7)
87.75(3)
125.30
132.34
126.49
82.73(12)
86.96(12)
88.02(5)
125.62
132.04
126.46
Acknowledgements
´
Financial support of this work by Direccion General de
The most significant difference between the solid state
conformation of the free ligand b and the coordinated
ligand in 2b is the angle between planes O(1)–C(11)–
C(12) and C(12)–C(13)–P(1) (53.11(13)ꢁ and 30.9(4)ꢁ,
respectively). Similar values are found for complexes 2c
30.6(3)ꢁ and 2d 30.0(6)ꢁ. This value also diminishes slightly
once the ligand is complexed to Ni or Pd: 38.4(2)ꢁ, 33.3(2)ꢁ
and 41.3(2)ꢁ [28]. The relative position of the phenyl rings
bonded to the N–CO-moiety stays without major variation
upon coordination. In the free ligand both rings are nearly
perpendicular (81.7ꢁ) and so happens in 2b (79.8ꢁ), 2c
(81.8ꢁ) and 2d (81.3ꢁ) while in the reported Ni complex
the phenyl bonded to N rotated, becoming both rings par-
allels (10.2ꢁ) [28].
´
Investigacion (Project CTQ2005-09231-C02-01/02) and
´
´
´
Fundacion Seneca de la Region de Murcia (Projects
00484/PI/04 and 03010/PI/05) is gratefully acknowledged.
Appendix A. Supplementary material
CCDC 631104, 631105 and 631106 contain the supple-
mentary crystallographic data for 2b, 2c and 2d. These data
can be obtained free of charge via http://www.ccdc.cam.ac.
uk/conts/retrieving.html, or from the Cambridge Crystal-
lographic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: +(44) 1223-336-033; or e-mail: deposit@
ccdc.cam.ac.uk.
The new complexes exhibꢀit intermolecular hydrogen
bonding between F from PF6 and N(1) atoms (distance
References
˚
N(1)ꢂ ꢂ ꢂF ranges 2.912–2.916 A and angle N(1)–Hꢂ ꢂ ꢂF
[1] A. Bader, E. Lindner, Coord. Chem. Rev. 108 (1991) 27.
[2] G.R. Newkome, Chem. Rev. 93 (1993) 2067.
[3] C.S. Slone, D.A. Weinberger, C.A. Mirkin, Prog. Inorg. Chem. 48
(1999) 233.
[4] P. Braustein, F. Naud, Angew. Chem., Int. Ed. 40 (2001) 680, and
references cited therein.
[5] P. Braustein, J. Organomet. Chem. 689 (2004) 3953, and references
cited therein.
[6] G.M. Kapteijn, M.P.R. Spee, D.M. Grove, H. Kooijman, A.L. Spek,
G. van Koten, Organometallics 15 (1996) 1405.
[7] P. Braunstein, C. Frison, X. Morise, R.A. Adams, J. Chem. Soc.,
Dalton Trans. (2000) 2205.
[8] M.S. Khoshbin, M.V. Ovchinnikov, C.A. Mirkin, L.N. Zakharov,
A.L. Rheingold, Inorg. Chem. 44 (2005) 496, and references cited
therein.
[9] C.W. Rogers, Y. Zhang, B.O. Patrick, W.E. Jones Jr., M.O. Wolf,
Inorg. Chem. 41 (2002) 1162.
[10] C.W. Rogers, M.O. Wolf, Coord. Chem. Rev. 233–234 (2002) 341.
[11] C.W. Rogers, M.O. Wolf, Angew. Chem., Int. Ed. 41 (2002) 1898.
[12] M. Kuriyama, K. Nagai, K. Yamada, Y. Miwa, T. Taga, K.
Tomioka, J. Am. Chem. Soc. 124 (2002) 8932.
ranges 152.37–155.01ꢁ).
In order to induce amide deprotonation in the ligands,
and a likely j2-P,N coordination mode according to our
previous studies with other metals, compounds 2a–d were
treated with KOH(aq) in acetone, as explained in the
experimental section, to yield neutral complexes
[RuCl(g6-p-cymene)(o-Ph2P–C6H4–CO–N–R)]
(R = iPr
(3a); R = Ph (3b); R = 4-MeC6H4 (3c); R = 4-FC6H4
(3d)) (Scheme 1). The loss of both m(NH) and m(PF) bands
in their IR spectra with regards to precursor compounds
confirmed that the proposed reactions took place. The
characterization in solid state was completed with the
FAB mass spectrometry, that shows fragments at [M+]
and [M+ ꢀ Cl]. A singlet shifted at ca. 7 ppm highfield
compared to PꢂO-chelated compounds characterizes the
31P{1H} NMR spectra, and the expected pattern is
observed in the 1H NMR with significant absence of amidic
proton resonance at low field. The solutions of new com-
plexes turned black after 48 h thus preventing the obten-
tion of crystals suitable for a diffraction analysis and a
[13] F.Y. Kwong, W.H. Lam, C.H. Yeung, K.S. Chan, A.S.C. Chan,
Chem. Commun. (2004) 1922.
[14] W-M. Dai, Y. Zhang, Tetrahedron Lett. 46 (2005) 1377.

2918
G. Sa´nchez et al. / Polyhedron 26 (2007) 2911–2918
[15] H.Y. Kwon, s.Y. Lee, B.Y. Lee, D.M. Shin, Y.K. Chung, J. Chem.
Soc., Dalton Trans. (2004) 921.
[24] P. Govindaswamy, Y.A. Mozharivskyj, M.R. Kollipara, Polyhedron
23 (2004) 3115.
´
´
´
˜
[16] R. Tribo, S. Munoz, J . Pons, R. Yanez, A. Alvarez-Larena, J.F.
[25] P. Bhattacharyya, T.Q. Ly, A.M.Z. Slawin, J.D. Woollins, Polyhe-
dron 20 (2001) 1803.
˜
Piniella, J. Ros, J. Organomet. Chem. 690 (2005) 4072.
´
´
[17] A. Caballero, F.A. Jalon, B.R. Manzano, G. Espino, M. Perez-
Manrique, A. Mucientes, F.J. Poblete, M. Maestro, Organometallics
23 (2004) 5694.
[26] S. Burger, B. Therrien, G. Suss-Fink, Inorg. Chim. Acta357 (2004) 1213.
¨
´
´
´
´
[27] G. Sanchez, J. Garcıa, D. Meseguer, J.L. Serrano, L. Garcıa, J. Perez,
´
G. Lopez, J. Chem. Soc., Dalton Trans. (2003) 4709.
[18] V. Cadierno, P. Crochet, J. Diez, J. Garcia-Alvarez, SE. Garcia-
Garrido, J. Gimeno, S. Garcia-Granda, M.A. Rodriguez, Inorg.
Chem. 42 (2003) 3293.
[28] G. Sa´nchez, J. Garc´ıa, D. Meseguer, J.L. Serrano, L. Garc´ıa, J. Pe´rez,
´
G. Lopez, Inorg. Chim. Acta 359 (2006) 1650.
[29] M.A. Bennett, T.-N. Huang, T.W. Matheson, A.K. Smith, Inorg.
Synth. 21 (1982) 74.
´
´
´
[19] V. Cadierno, P. Crochet, J. Garcıa-Alvarez, S.E. Garcıa-Garrido, J.
Gimeno, J. Organomet. Chem. 663 (2002) 32.
[30] SAINT, Version 6.22, Bruker AXS Inc.
[20] C. Stanfest-Hauser, C. Slugovc, K. Mereiter, R. Schimd, K. Kirchner,
L. Xiao, W. Weissensteiner, J. Chem. Soc., Dalton Trans. (2001)
2989.
[31] G.M. Sheldrick, SADABS, University of Gottingen, 1996.
[32] G.M. Sheldrick, SHELX-97. Programs for Crystal Structure Analysis
(Release 97-2), University of Go¨ttingen, Germany, 1998.
[33] J.F. Faller, B.P. Patel, M.A. Albrizzio, M. Curtis, Organometallics 18
(1999) 3096.
´
´
[21] I. Moldes, E. de la Encarnacion, J. Ros, A. Alvarez-Larena, J.F.
Piniella, J. Organomet. Chem. 566 (1998) 165.
´
´
´
[22] V. Cadierno, J. Dıez, S.E. Garcıa-Garrido, S. Garcıa-Granda, J.
[34] C.G. Arena, S. Calamia, F. Faraone, C. Graiff, A. Tiripicchio, J.
Chem. Soc., Dalton Trans. (2000) 3149.
Gimeno, J. Chem. Soc., Dalton Trans. (2002) 1465.
[23] G. Henig, M. Schulz, B. Windmuller, H. Werner, J. Chem. Soc.,
¨
[35] H. Yang, N. Lugan, R. Mathieu, Ann. Quim. Int. Ed. 93 (1997) 28.
[36] F.H. Allen, R. Taylor, Acta Crystallogr. B47 (1991) 404.
Dalton Trans. (2003) 441.