New acylhydridorhodium(III) complexes containing terdentate PNN ligands from the reaction of diolefinic rhodium(I) complexes with o-(diphenylphosphino) benzaldehyde in the presence of chelating amino ligands

Article abstract of DOI:10.1016/j.ica.2003.11.008

[{Rh(cod)Cl}₂] (cod=1,5-cyclooctadiene) reacts with o-(diphenylphosphino)benzaldehyde (PPh₂(o-C₆H ₄CHO)) (Rh:P=1:1) in the presence of aromatic diamines or 8-aminoquinoline (NN) to give acylhydride [Rh(Cl)(H){PPh₂(o-C ₆H₄CO)}(NN)] species. The oxidative addition of PPh ₂(o-C₆H₄CHO) in the presence of (NN) and PPh₃ gives cationic species [Rh(H){PPh₂(o-C ₆H₄CO)} (PPh₃)(NN)]⁺ containing mutually trans phosphorus atoms. When (NN)=8-aminoquinoline, a mixture of two isomers is obtained. These isomers differ in the nitrogen cis to the hydride, amino or quinolinic. By using Rh:PPh₂(o-C₆H ₄CHO)=1:2 stoichiometric ratios, oxidative addition of one PPh ₂(o-C₆H₄CHO) and P-coordination of another PPh₂(o-C₆H₄CHO) occurs. The aldehyde group undergoes then a condensation reaction with the coordinated amine to afford new PNN terdentate ligands, phosphine-amino-imine when (NN)=diamine or phosphine-diimine when (NN)=8-aminoquinoline. These reactions give selectively the corresponding complexes [Rh(H){PPh₂(o-C₆H ₄CO)}(PNN)]⁺ containing trans phosphorus atoms and the hydride cis to the new imino group. X-ray diffraction studies of the PNN complexes are reported.

Full text of DOI:10.1016/j.ica.2003.11.008

Inorganica Chimica Acta 357 (2004) 2818–2826
www.elsevier.com/locate/ica
New acylhydridorhodium(III) complexes containing terdentate
PNN ligands from the reaction of diolefinic rhodium(I)
complexes with o-(diphenylphosphino)benzaldehyde in the
presence of chelating amino ligands
a,
Marıa A. Garralda , Ricardo Hernandez , Lourdes Ibarlucea , Elena Pinilla ,
a
a
b
*
ꢀ
ꢀ
M. Rosario Torres , Malkoa Zarandona
b
a
a
Facultad de Quꢀımica de San Sebastiꢀan, Universidad del Paꢀıs Vasco, Apdo. 1072, 20080 San Sebastiꢀan, Spain
b
Departamento de Quꢀımica Inorgꢀanica, Laboratorio de Difracciꢀon de Rayos X, Facultad de Ciencias Quꢀımicas, Universidad Complutense,
28040 Madrid, Spain
Received 15 October 2003; accepted 8 November 2003
Available online 7 January 2004
Abstract
[{Rh(cod)Cl}2] (cod ¼ 1,5-cyclooctadiene) reacts with o-(diphenylphosphino)benzaldehyde (PPh2(o-C6H4CHO)) (Rh:P ¼ 1:1) in
the presence of aromatic diamines or 8-aminoquinoline (NN) to give acylhydride [Rh(Cl)(H){PPh2(o-C6H4CO)}(NN)] species. The
oxidative addition of PPh2(o-C6H4CHO) in the presence of (NN) and PPh3 gives cationic species [Rh(H){PPh2(o-C6H4CO)}
(PPh3)(NN)]þ containing mutually trans phosphorus atoms. When (NN) ¼ 8-aminoquinoline, a mixture of two isomers is obtained.
These isomers differ in the nitrogen cis to the hydride, amino or quinolinic. By using Rh:PPh2(o-C6H4CHO) ¼ 1:2 stoichiometric
ratios, oxidative addition of one PPh2(o-C6H4CHO) and P-coordination of another PPh2(o-C6H4CHO) occurs. The aldehyde group
undergoes then a condensation reaction with the coordinated amine to afford new PNN terdentate ligands, phosphine-amino-imine
when (NN) ¼ diamine or phosphine-diimine when (NN) ¼ 8-aminoquinoline. These reactions give selectively the corresponding
complexes [Rh(H){PPh2(o-C6H4CO)}(PNN)]þ containing trans phosphorus atoms and the hydride cis to the new imino group.
X-ray diffraction studies of the PNN complexes are reported.
Ó 2003 Elsevier B.V. All rights reserved.
Keywords: Rhodium; Acylhydride; Imination reactions; Terdentate PNN ligands
1. Introduction
and the palladium complexes obtained have been used in
catalytic allylic alkylations [3] or aminations [4] and in
copolymerization of olefins-carbon monoxide [5]. Some
rhodium(I) derivatives containing bidentate imino-
phosphines behave as oxygen carriers [6] and 2-diph-
enylphosphinobenzylideneaminopiperidine (L) affords a
rhodium(III) complex CpꢀRhCl2L that contains P-
monodentate L [7]. The reaction of PPh2(o-C6H4CHO)
with primary diamines may afford tetradentate chelating
PNNP ligands [8] that can also function as PNP [8a,9] or
PNN terdentate [10]. The ruthenium derivatives con-
taining asymmetric diphosphinediimine ligands have
been used in the asymmetric transfer hydrogenation of
ketones [11] and in the epoxidation of olefins [12]. Po-
tentially terdentate PNN ligands have been prepared by
Hemilabile ligands containing soft and hard donor
atoms and their use to afford transition metal complexes
have been extensively studied, in particular with respect
to the development of novel homogeneous catalysts
precursors [1]. Since its preparation by Rauchfuss
o-(diphenylphosphino)benzaldehyde (PPh2(o-C6H4CHO))
has been widely used to prepare hemilabile PN-donor
ligands, by condensation of the aldehyde group with
primary amines [2]. The isolated iminophosphines PN
behave as bidentate ligands towards transition metals
* Corresponding author. Tel.: +34-943-018207; fax: +34-943-212236.
E-mail address: qppgahum@sq.ehu.es (M.A. Garralda).
0020-1693/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2003.11.008

M.A. Garralda et al. / Inorganica Chimica Acta 357 (2004) 2818–2826
2819
the reaction of aminopyridines with PPh2(o-C6H4CHO).
These ligands can behave as P-monodentates, PN bid-
entates or PNN terdentates [13].
m(C@O); 289(w) m(Rh–Cl). 1H NMR (CDCl3): d – 15.69
(t, RhH, J(Rh,H) 23 Hz, J(P,H) 23 Hz); 5.54 and 5.19 (m,
NH2 (trans to phosphorus)); 4.12 and 3.21 (s, br, NH2 (cis
to phosphorus)). 31P{1H} NMR (CDCl3): d 75.6 (d, P-
acyl, J(Rh,P) 165 Hz). Anal. Calc. for C25H23ClN2OPRh:
C, 55.94; H, 4.32; N, 5.22. Found: C, 55.93; H, 4.57; N,
5.16%.
The condensation reaction of aldehydes and amines
occurs via hemiaminal >C(OH)NHR intermediates that
lose water readily to give the imine group. Recently, we
have reported that Rh(cod)(bdh)Cl (cod: 1,5-cyclooct-
adiene; bdh: H2NN@C(CH3)C(CH3)@NNH2), prepared
‘‘in situ’’, reacts with PPh2(o-C6H4CHO) to give a mix-
ture of two compounds, a hydroxyalkyl derivative [Rh
{PPh2(o-C6H4CO)}{PPh2(o-C6H4CHOH)}(bdh)]þ, and
an acylhydrido complex [RhH{PPh2(o-C6H4CO)}
(Pbdh)]þ containing a terdentate PNN (Pbdh) ligand.
Both types of compounds can be formed selectively by
use of the appropriate reagents [14]. The terdentate Pbdh
ligand contains a stable hemiaminal group, in a seven-
member metallocycle, formed by the reaction of aldehyde
and the pendant amino group of the coordinated bdh. We
report now on the reactions of [{Rh(cod)Cl}2] with
PPh2(o-C6H4CHO) in the presence of potentially che-
lating amino ligands such as 1,2-phenylenediamine (da-
phen), 2,4-diaminotoluene (dat) or 8-aminoquinoline
(aqui).
2.2. [Rh(H){PPh2(o-C6H4CO)}(PPh3)(daphen)]
BPh4 (2)
To a MeOH suspension of [{Rh(cod)Cl}2] (0.06
mmol) were added stoichiometric amounts of daphen
(0.12 mmol), PPh3 (0.12 mmol) and PPh2(o-C6H4CHO)
(0.12 mmol) to obtain a yellow suspension. Subsequent
addition of NaBPh4 (0.12 mmol) gave a yellow-greenish
solid that was filtered, washed with MeOH and vacuum
dried. IR (KBr, cmꢁ1): 3285(s), 3247(s) m(NH2);
2063(m), m(RhH); 1632(s), m(C@O). KM (ohmꢁ1 cm2 mol
1
ꢁ1): 101 (acetone). H NMR (CDCl3): d – 13.56 (ddd,
RhH, J(Rh,H) 19 Hz, J(PPh3,H) 11 Hz, J(P-acyl,H) 6
Hz); 6.04 and 5.78 (m, NH2 (trans to hydride)); 2.88 (AB
system, NH2 (cis to hydride), J(H,H) 12.1 Hz). 31P{1H}
NMR (CDCl3): d 62.7 (dd, P-acyl, J(Rh,P) 131 Hz,
J(P,P) 333 Hz); 46.1 (dd, PPh3, J(Rh,P) 123 Hz). FAB
MS: calcd. for C43H38N2OP2Rh: 763; observed: 763
[M]þ (16%), 627 [M-daphen-CO]þ (100%), 501 [M-
PPh3]þ (69%). Anal. Calc. for C67H58BN2OP2Rhx
MeOH: C, 73.26; H, 5.61; N, 2.51. Found: C, 72.65; H,
5.54; N, 2.51%.
2. Experimental
The preparation of the metal complexes was carried
out at room temperature under nitrogen by standard
Schlenk techniques. [{Rh(cod)Cl}2] [15] was prepared as
previously reported. o-(diphenylphosphine)benzalde-
hyde was purchased from Aldrich and used as received.
Microanalysis was carried out with a Leco CHNS-932
microanalyser. Conductivities were measured in acetone
solution with a Metrohm E 518 conductimeter. IR
spectra were recorded with a Nicolet FTIR 740 spec-
trophotometer in the range 4000–50 cmꢁ1 using KBr
pellets or nujol mulls between polyethylene sheets.
NMR spectra were recorded with Bruker Avance DPX
2.3. [Rh(H){PPh2(o-C6H4CO)}(Pdaphen)]X (X ¼ BPh4,
3a; X ¼ ClO4, 3b)
To a CH2Cl2 solution of [{Rh(cod)Cl}2] (0.06 mmol)
was added a stoichiometric amount of daphen (0.12
mmol) whereupon a yellow precipitate was formed that
upon addition of PPh2(o-C6H4CHO) (0.24 mmol) gave
an orange solution. Stirring for 25 min gave a yellow
precipitate of [Rh(H){PPh2(o-C6H4CO)}(Pdaphen)]Cl
that was filtered, washed with dichloromethane and
vacuum dried (85% yield). This solid (0.12 mmol) was
dissolved in MeOH and NaBPh4 or NaClO4 (0.08 mmol)
was added to give precipitates that were filtered, washed
with MeOH and vacuum dried. IR (KBr, cmꢁ1): 3296(s),
3243(s) m(NH2); 2056(w), m(RhH); 1621(s), m(C@O). KM
(ohmꢁ1 cm2 mol ꢁ1): 83 (acetone). 1H NMR (CDCl3): d –
14.71 (ddd, RhH, J(Rh,H) 23 Hz, J(Pdaphen,H) 19 Hz,
J(P-acyl,H) 7 Hz); 3.53 (AB system, NH2, J(H,H) 10.7
Hz). 31P{1H} NMR (CDCl3): d 55.5 (dd, P-acyl, J(Rh,P)
128 Hz, J(P,P) 348 Hz); 37.1 (dd, Pdaphen, J(Rh,P) 123
Hz). 13C{1H} NMR (DMSO-d6): d 234.1 (d, C@O,
J(Rh,C) 29 Hz); 166.4 (s, C@N). FAB MS: calcd. for
C44H36N2OP2Rh: 773; observed: 773 [M]þ (100%), 483
[M-{PPh2(o-C6H4CHO)}]þ (27%). Anal. Calc. for
C68H56BN2OP2 Rhx1.5MeOH: C, 73.17; H, 5.48; N, 2.46.
1
300 or Bruker Avance 500 spectrometers, H and 13C
(TMS internal standard) and 31P (H3PO4 external
standard) spectra were measured from CDCl3 or
DMSO-d6 solutions. Mass spectra were recorded on a
VG Autospec, by liquid secondary ion (LSI) MS using
nitrobenzylalcohol as matrix and a caesium gun (Uni-
versidad de Zaragoza).
2.1. [Rh(Cl)(H){PPh2(o-C6H4CO)}(daphen)] (1)
To a benzene solution of [{Rh(cod)Cl}2] (0.06 mmol)
was added a stoichiometric amount of daphen (0.12
mmol) to obtain a yellow suspension. Addition of
PPh2(o-C6H4CHO) (0.12 mmol) and stirring for 30 min
at room temperature gave a yellow solid that was filtered,
washed with benzene and vacuum dried. IR (cmꢁ1):
3302(s), 3227(s) m(NH2); 2038(s), m(RhH); 1611(s),

2820
M.A. Garralda et al. / Inorganica Chimica Acta 357 (2004) 2818–2826
Found: C, 72.76; H, 5.52; N, 2.59% for 3a. Anal. Calc. for
C44H36ClN2O5P2Rhx0.5CH2Cl2: C, 58.38; H, 4.07; N,
3.06. Found: C, 57.79; H, 4.03; N, 3.16% for 3b.
73.2 (d, P-acyl, J(Rh,P) 166 Hz) for 7b. Anal. Calc. for
C28H23ClN2OPRh: C, 58.71; H, 4.05; N, 4.89. Found:
C, 58.75; H, 4.06; N, 4.40%.
2.4. [Rh(Cl)(H){PPh2(o-C6H4CO)}(dat)](5)
2.7. [Rh(H){PPh2(o-C6H4CO)}(PPh3)(aqui)]BPh4
(8)
To a benzene solution of [{Rh(cod)Cl}2] (0.06 mmol)
was added a stoichiometric amount of dat (0.12 mmol)
to obtain a yellow suspension. Addition of PPh2(o-
C6H4CHO) (0.12 mmol) and stirring for 30 min at room
temperature gave a yellow solid that was filtered, wa-
shed with benzene and vacuum dried. IR (cmꢁ1):
3333(s), 3212(s) m(NH2); 2021(s), m(RhH); 1625(s),
m(C@O); 278(w) m(Rh–Cl). 1H NMR (CDCl3): d – 15.67
(m, br, RhH); 5.45, 5.08, 3.99 and 3.13 (s, br, NH); 2.34
and 2.22 (s, CH3). 31P{1H} NMR (CDCl3): d 75.6 (d, P-
acyl, J(Rh,P) 163 Hz); d 75.5 (d, P-acyl, J(Rh,P) 165
Hz). Anal. Calc. for C26H25ClN2OPRh: C, 56.69; H,
4.57; N, 5.09. Found: C, 56.15; H, 4.89; N, 4.74%.
To a MeOH suspension of [{Rh(cod)Cl}2] (0.06
mmol) were added stoichiometric amounts of aqui (0.12
mmol) and PPh3 (0.12 mmol) to obtain a red suspen-
sion. Subsequent addition of PPh2(o-C6H4CHO) (0.12
mmol) gave a red solution that upon addition of
NaBPh4 (0.12 mmol) gave a white precipitate that was
filtered, washed with MeOH and vacuum dried. IR
(KBr, cmꢁ1): 3272(m), 3255(m) m(NH2); 2054(w),
m(RhH); 1624(s), m(C@O). KM (ohmꢁ1 cm2 mol ꢁ1): 100
(acetone). 1H NMR (CDCl3): d – 13.24 (ddd, RhH,
J(Rh,H) 19 Hz, J(PPh3,H) 11 Hz, J(P-acyl,H) 6 Hz);
3.89 (d, NH, J(H,H) 13.7 Hz); 3.12 (d, NH) for 8a; d
)13.69 (ddd, RhH, J(Rh,H) 22 Hz, J(PPh3,H) 11 Hz,
J(P-acyl,H) 7 Hz); 3.66 (d, NH, J(H,H) 13.2 Hz); 3.21
(d, NH) for 8b. 31P{1H} NMR (CDCl3): d 64.7 (dd, P-
acyl, J(Rh,P) 130 Hz, J(P,P) 336 Hz); 47.6 (dd, PPh3,
J(Rh,P) 123 Hz) for 8a; d 65.3 (dd, P-acyl, J(Rh,P) 131
Hz, J(P,P) 339 Hz); 42.0 (dd, PPh3, J(Rh,P) 119 Hz) for
8b. 13C{1H} NMR (CDCl3): d 237 (d, C@O, J(Rh,C)
110 Hz). FAB MS: calcd. for C46H38N2OP2Rh: 799;
observed: 799 [M]þ (16%), 627 [M-aqui-CO]þ (31%),
537 [M-PPh3]þ (100%). Anal. Calc. for C70H58BN2OP2
RhxMeOH: C, 74.09; H, 5.43; N, 2.43. Found: C, 74.04;
H, 5.46; N, 2.72%.
2.5. [Rh(H){PPh2(o-C6H4CO)}(Pdat)]BPh4 (6)
To a MeOH suspension of [{Rh(cod)Cl}2] (0.06
mmol) were added stoichiometric amounts of dat (0.12
mmol), PPh2(o-C6H4CHO) (0.24 mmol) and NaBPh4
(0.12 mmol). Stirring for 30 min gave a yellow precipi-
tate that was filtered, washed with MeOH and vacuum
dried. IR (KBr, cmꢁ1): 3293(m), 3249(m) m(NH2);
2053(w) m(RhH); 1633(s), m(C@O). KM (ohmꢁ1 cm2 mol
ꢁ1): 90 (acetone). 1H NMR (CDCl3): d – 14.68 (m,
RhH); 3.37 (m, NH); 2.06 and 1.93 (s, CH3). 31P{1H}
NMR (CDCl3): d 55.5 (dd, P-acyl, J(Rh,P) 127 Hz,
J(P,P) 349 Hz); 37.3 (dd, Pdat, J(Rh,P) 122 Hz); d 55.6
(dd, P-acyl, J(Rh,P) 127 Hz, J(P,P) 347 Hz); 37.2 (dd,
Pdat, J(Rh,P) 122 Hz). 13C{1H} NMR (DMSO-d6): d
233.7 and 233.5 (d, C@O, J(Rh,C) 27 Hz); 165.5 and
164.9 (s, C@N); 20.4 and 20.2 (s, CH3). FAB MS: calc.
for C45H38N2OP2Rh: 787; observed: 787 [M]þ (100%),
497 [M-{PPh2(o-C6H4CHO)}]þ (32%). Anal. Calc. for
C69H58BN2OP2RhxMeOH: C, 73.82; H, 5.49; N, 2.46.
Found: C, 73.41; H, 4.89; N, 2.59%.
2.8. [Rh(H){PPh2(o-C6H4CO)}(Paqui)]BPh4 (9)
To a CH2Cl2 solution of [{Rh(cod)Cl}2] (0.06 mmol)
was added a stoichiometric amount of aqui (0.12 mmol)
whereupon an orange precipitate was formed that upon
addition of PPh2(o-C6H4CHO) (0.24 mmol) gave a
yellow solution. Stirring for 25 min and addition of di-
ethyl ether gave a yellow precipitate of [Rh(H){PPh2(o-
C6H4CO)}(Paqui)]Cl that was filtered, washed with di-
ethyl ether and vacuum dried (85% yield). This solid
(0.08 mmol) was dissolved in MeOH and NaBPh4 (0.08
mmol) was added to give a yellow precipitate that was
filtered, washed with MeOH and vacuum dried. IR
(KBr, cmꢁ1): 2042(w), m(RhH); 1633(s), m(C@O). KM
2.6. [Rh(Cl)(H){PPh2(o-C6H4CO)}(aqui)] (7)
To an EtOH suspension of [{Rh(cod)Cl}2] (0.06
mmol) were added stoichiometric amounts of aqui (0.12
mmol) and PPh2(o-C6H4CHO) (0.12 mmol). Stirring for
30 min at room temperature gave a white precipitate
that was filtered, washed with EtOH and vacuum dried.
IR (cmꢁ1): 3239(m), 3151(m) m(NH2); 2059(s), m(RhH);
1
(ohmꢁ1 cm2 mol ꢁ1): 94 (acetone). H NMR (CDCl3): d
– 13.66 (dt, RhH, J(Rh,H) 20 Hz, J(Paqui,H) 20 Hz,
J(P-acyl,H) 4 Hz). 31P{1H} NMR (CDCl3): d 60.4 (dd,
P-acyl, J(Rh,P) 123 Hz, J(P,P) 352 Hz); 35.2 (dd, Paqui,
J(Rh,P) 123 Hz). 13C{1H} NMR (CDCl3): d 239.9 (d,
C@O, J(Rh,C) 110 Hz); 167.1 (s, C@N). FAB MS:
calcd. for C47H36N2OP2Rh: 809; observed: 809 [M]þ
(100%), 519 [M-{PPh2(o-C6H4CHO)}]þ (50%). Anal.
Calc. for C71H56BN2OP2 Rh: C, 75.54; H, 5.00; N, 2.48.
Found: C, 75.04; H, 4.47; N, 2.45%.
1
1628(s), m(C@O); 281(w), m(Rh–Cl). H NMR (CDCl3):
d – 15.84 (t, RhH, J(Rh,H) 24 Hz, J(P,H) 24 Hz); 6.00
(d, NH, J(H,H) 8.3 Hz); 5.76 (d, NH) for 7a; d )15.16 (t,
RhH, J(Rh,H) 26 Hz, J(P,H) 26 Hz); 4.62 (d, NH,
J(H,H) 11.7 Hz); 3.68 (d, NH) for 7b. 31P{1H} NMR
(CDCl3): d 74.6 (d, P-acyl, J(Rh,P) 168 Hz) for 7a; d

M.A. Garralda et al. / Inorganica Chimica Acta 357 (2004) 2818–2826
2821
2.9. X-ray structure determination of 3b and 9
and it was attributed to two half-molecules of the sol-
vent (chloroform). This is probably the reason for
the diffraction decay upon X-ray exposure. All non-
hydrogen atoms have been refined anisotropically with
exceptions. The perchlorate anion, some nitrogen atoms
and half-molecule of the solvent, CHCl3, were refined
isotropically only two cycles and in the last cycles of
refinement the thermal factors have been fixed. The
other solvent half-molecule was anisotropically refined
only two cycles and the thermal factors have been fixed.
Some of these atoms were refined with geometrical re-
straints and a variable common carbon–nitrogen and
carbon–chlorine distances. All hydrogen atoms were
calculated and refined as riding on a carbon or nitrogen
bonded atom with a common isotropic displacement
parameters. It has not been possible to locate the hy-
dride in a Fourier synthesis. These features led to a high
R factor (Table 1). In compound 9, the heavy atom has
been located by Patterson function and the rest of the
atoms by Fourier synthesis. The refinement was done by
full-matrix least-squares on F 2 [16]. All non-hydrogen
atoms have been refined anisotropically. The dichlo-
romethane molecule was refined with geometrical re-
straints and a variable carbon–chlorine distance. The
hydrogen atoms were calculated and refined as riding
on a carbon bonded atom with a common isotropic
Yellow needle-shaped single crystals of [Rh(H)
{PPh2(o-C6H4CO)}(Pdaphen)]ClO4 ꢂ CHCl3 3b were
grown by slow diffusion of diethyl ether onto chloro-
form solutions. Prismatic single yellow crystals of
[Rh(H){PPh2(o-C6H4CO)}(Paqui)]BPh4 ꢂ 1/2CH2Cl2
9
were grown by layering dichloromethane solutions with
diethyl ether. The data for both compounds were col-
lected on a Bruker Smart CCD diffractometer with
ꢁ
graphite-monochromated Mo Ka (k ¼ 0:71073 A) ra-
diation operating at 50 kV and 15 mA. Data were col-
lected over a hemisphere of the reciprocal space by
combination of three exposure sets. Each exposure of 10
and 30 s, for 3b and 9, respectively, covered 0.3° in x.
The first 50 frames were re-collected at the end of the
data collection to monitor crystal decay. Many attempts
were made to collect good data for 3b, but in all cases
the diffraction pattern was poorer after X-ray exposi-
tion. The best data collection show a decay of 18% in the
intensities of standard reflections. A summary of the
fundamental crystal data is given in Table 1. The
structure of 3b was solved by direct methods and con-
ventional Fourier techniques. The refinement was done
by full-matrix least-squares on F 2 [16]. After two cycles
of isotropic refinement some electron density was found
Table 1
Crystal and refinement data for [Rh(H){PPh2(o-C6H4CO)}(Pdaphen)]ClO4 ꢂ CHCl3 (3b) and [Rh(H){PPh2(o-C6H4CO)}(Paqui)]BPh4 ꢂ 1/2CH2Cl2
(9)
3b
9
Empirical formula
Formula weight
Temperature (K)
[C44H36ClN2O5P2Rh] ꢂ CHCl3
[C71H56BN2OP2Rh] ꢂ 1/2(CH2Cl2)
992.42
296(2)
1171.30
296(2)
ꢁ
Wavelength (A)
0.71073
monoclinic
0.71073
monoclinic
Crystal system
Space group
P2ð1Þ=c
P2ð1Þ=n
ꢁ
a (A)
15.836(6)
19.191(8)
14.900(1)
19.731(2)
ꢁ
b (A)
ꢁ
c (A)
17.440(7)
91.613(9)
5298(4)
20.965(2)
97.448(2)
6111.7(9)
b (°)
Volume (A )
3
ꢁ
Z
4
1.244
4
1.273
Density (mg/m3) (calculated)
Absorption coefficient (mmꢁ1
F (0 0 0)
)
0.624
2016
0.420
2420
Crystal size (mm3)
0.20 ꢃ 0.08 ꢃ 0.08
0.27 ꢃ 0.24 ꢃ 0.10
h Range for data collection (°)
Index ranges
Decay (%)
1.29 to 25.00
()17, )21, )20 to 18, 22, 20)
18
1.42 to 23.00
()15, )21, )20 to 16, 21, 23)
–
26,701
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F 2
Final Raindices [I > 2rðIÞ]
14,849
6657 [Rint ¼ 0:212]
8505 [Rint ¼ 0:104]
6658/10/389
0.987
8505/2/718
0.935
0.156 (1917 observed reflections)
0.3955
0.0611 (3898 observed reflections)
0.2003
b
wR2 indices (all data)
P
P
a
[jFoj ꢁ jFcj]/ jFoj.
n
o
1=2
P
P
2
2
b
½wðFo2 ꢁ Fc2Þ ꢄ= ½wðFo2Þ ꢄ
.

2822
M.A. Garralda et al. / Inorganica Chimica Acta 357 (2004) 2818–2826
displacement parameters, except the hydride, which has
been located in a Fourier synthesis, included and its
parameters refined. The largest residual peaks in the ꢁfi3-
observed. According to a NOESY experiment, NOE ef-
fects are observed between both amino groups and the
hydride, showing that both groups are cis to the hydride.
In the absence of other effects, these signals are expected
to shift downfield upon coordination, but the ring current
effects originated by the aromatic rings of the phosphine
can shift the signals in the opposite sense (upfield),
therefore we assign the resonances at 5.54 and 5.19 ppm
to the amino group trans to phosphorus and the signals at
4.12 and 3.21 ppm to the amino group cis to phosphorus.
The 31P{1H} NMR spectrum shows a doublet at low field
(75.6 ppm) due to the five-member ring effect [18].
ꢁ
nal Fourier difference map were 1.56 and 1.38 e A
near the solvent molecules, for 3b and 9, respectively.
3. Results and discussion
The reaction of [{Rh(cod)Cl}2] with PPh2(o-C6H4
CHO) (Rh:P ¼ 1:1) in the presence of 1,2-phenylenedi-
amine (daphen) (Rh:daphen ¼ 1:1) leads to the formation
of the chelate-assisted oxidative addition product,
[Rh(Cl)(H)[PPh2(o-C6H4CO)] (daphen)] (1) with dis-
placement of 1,5-cyclooctadiene as shown in Scheme 1(i).
Complex 1 contains a coordinated diamino ligand. The
IR spectrum of the acylhydrido complex formed shows
the expected absorptions due to the coordinated diamine,
m(Rh–H) at 2038 cmꢁ1 and m(C@O) at 1611 cmꢁ1, at
lower frequency than in the free ligand, indicating acyl
When the previous reaction is performed in the
presence of triphenylphosphine (Rh:PPh3 ¼ 1:1), the
oxidative addition reaction occurs and also the dis-
placement of chlorine by PPh3 to afford the cationic
species [Rh(H){PPh2(o-C6H4CO)}(PPh3)(daphen)]þ (2)
(Scheme 1(ii)) that has been isolated as its tetraphe-
nylborate salt, which behaves as 1:1 electrolyte in ace-
tone solution [19]. Its FAB spectrum shows the
corresponding [Mþ] peak. The 31P{1H} NMR spectrum
consists of two doublets of doublets corresponding to an
AMX pattern. The acylphosphine fragment (P-acyl)
shows the characteristic low field resonance, 62.7 ppm
((Rh,P) 131 Hz). The resonance of the coordinated PPh3
appears at 46.1 ppm (J(Rh,P) 123 Hz) and J(P,P) of 333
Hz, indicating trans arrangement of the phosphorus
1
coordination [17]. The H NMR spectrum shows a hy-
dride resonance in the high field region at )15.69 ppm, as
a triplet due to equals J(Rh,H) and J(P,H) of 23 Hz that
agree with the phosphine being cis to the hydride. All four
hydrogen atoms of the bonded amino groups are mag-
netically non-equivalent and two sets of resonances are
1
atoms. The H NMR spectrum shows a hydride reso-
nance in the high field region, at )13.56 ppm, as a
doublet doublet of doublet due to coupling with rho-
dium J(Rh,H) of 19 Hz, PPh3 J(P,H) of 11 Hz and P-
acyl J(P,H) of 6 Hz that agree with both phosphines
being cis to the hydride. The bonded amino groups
appear at 6.04 and 5.78 ppm as multiplets and at 2.88
ppm (AB system). A NOE effect is observed between the
signal at 2.88 ppm and the hydride, while no NOE effect
is observed between the hydride and the amino reso-
nances at ꢅ6 ppm. Therefore, we assign the latter res-
onances to the amino group trans to the hydride. The
low field value of these signals can be rationalized on
account of the relative flexibility of the diamino ligand.
This flexibility may allow this particular amino group to
withdraw from the phenyl rings.
The reaction of [{Rh(cod)Cl}2] with PPh2(o-
C6H4CHO) (Rh:P ¼ 1:2) in the presence of daphen
(Rh:daphen ¼ 1:1) leads to the oxidative addition of one
PPh2(o-C6H4CHO) and to the formation of a new
terdentate PNN (Pdaphen) ligand in complex
[Rh(H){PPh2(o-C6H4CO)}(Pdaphen)]þ (3) as shown in
Scheme 1(iii). Complex 3 has been isolated as tetra-
phenylborate salt [Rh(H){PPh2(o-C6H4CO)}(Pda-
phen)]BPh4 (3a) and the Pdaphen ligand contains a
phosphorus atom, an amino and an imino group. The
13C{1H} NMR spectrum of 3 shows the expected dou-
blet for the acyl group at 234.1 ppm (J(Rh,C) 29 Hz)
[13] and a singlet at 166.4 ppm due to the newly formed
Scheme 1.

M.A. Garralda et al. / Inorganica Chimica Acta 357 (2004) 2818–2826
2823
C@N bond, which correlates with a resonance at 7.74
ppm due to the imino proton, as shown by HMQC. The
31P{1H} NMR spectrum shows two doublets of dou-
blets corresponding to an AMX pattern and reveals that
only one isomer has been formed. The acylphosphine
appears at 55.5 ppm (J(Rh,P) 128 Hz), the resonance of
the new terdentate ligand Pdaphen in a six-member
metallocycle appears at 37.1 ppm (J(Rh,P) 123 Hz) and
J(P,P) of 333 Hz, indicating trans arrangement of the
phosphorus atoms. The 1H NMR spectrum shows a
hydride resonance in the high field region, at )14.71
ppm, as a doublet doublet of doublet due to coupling
with rhodium J(Rh,H) of 23 Hz, and with two cis
phosphines, Pdaphen J(P,H) of 19 Hz and P-acyl J(P,H)
of 7 Hz. The resonance of the remaining amino group
appears at 3.53 ppm (AB system) and no NOE effect is
observed between this NH2 signal and the hydride and
this could be due to the hydride being trans to the un-
reacted amino group. In order to obtain single crystals
and perform an X-ray diffraction study, we have pre-
pared the perchlorate salt (3b) that shows similar spec-
troscopic features to those of 3a. The results obtained
confirm the structure shown in Scheme 1 (vide infra).
We have followed this reaction in CD3OD at 253 K
and we have been able to detect the formation of com-
plex 4, shown in Scheme 1(iv). 4 contains acylphosphine
chelate (d P 57.1 {dd}ppm, J(Rh,P) 132 Hz), trans
(J(P,P) 342 Hz) to monodentate PPh2(o-C6H4CHO) (d
P 31.2 {dd}ppm, J(Rh,P) 125 Hz; d HCO 9.2 {br} ppm)
and hydride (d H-Rh )14.60 ppm {dt}, J(Rh,H) 21 Hz,
J(P-aldehyde,H) 21 Hz, J(P-acyl,H) 12 Hz). At 253 K, 4
is transformed slowly into 3 so that after 3 h a 4:3 ¼ 1:1
ratio is observed. On rising the temperature up to 293 K
4 is completely transformed into 3. The hydride reso-
nance of the condensation product 3 appears at )14.71
ppm, while the corresponding resonance in its non-
condensed precursor 4 appears at )14.6 ppm in agree-
ment with the hydride chemical shifts being sensitive to
the nature of the trans groups [20]. These results show
that PPh2(o-C6H4CHO) P-coordinates prior to the
condensation reaction, which occurs between the free
aldehyde and the amino group trans to the acyl group.
In this case the imination of the aldehyde goes to com-
pletion, while the reaction of the related Rh(cod)(bdh)Cl
with PPh2(o-C6H4CHO) affords a terdentate PNN
(Pbdh) ligand containing a hemiaminal group [14a]. This
different behaviour can be due to the different size of the
metallocycle formed, six-member in 3 and seven-mem-
ber in [Rh(H){PPh2(o-C6H4CO)}(Pbdh)]þ and/or to the
amino group being bonded in the precursor of 3 and
pendant in the precursor of [Rh(H){PPh2(o-
C6H4CO)}(Pbdh)]þ. It has been reported that coordi-
nation of aldehydes to iridium makes the corresponding
imination reaction with added amines much faster [21].
Most likely, in our case, the fast imination reaction is
due to chelate formation.
When the above reactions of [{Rh(cod)Cl}2] with o-
PPh2(o-C6H4CHO) (Rh:P ¼ 1:1 or 1:2) are performed in
the presence of 3,4-diaminotoluene (dat), complexes 5
and 6 are formed, respectively (see Scheme 1). 5 is a
mixture of two isomers in a 1:1 ratio. Both isomers
contain phosphine trans to nitrogen as shown by the
31P{1H} NMR spectrum that consists of two very close
doublets at 75.6 and 75.5 ppm, respectively, with
J(Rh,P) of ꢅ165 Hz. These isomers differ in the position
of the methyl substituent relative to a particular amino
group. The hydride resonance at )15.67 ppm is a com-
plex multiplet due to overlapping of the signals of both
isomers. 6 is also a mixture of almost equimolar
amounts of only two isomers that contain mutually
trans P-atoms and new terdentate PNN (Pdat) ligands.
The formation of the new imino groups is shown by the
appearance of two singlets at 165.5 and 164.9 ppm in the
13C{1H} NMR spectrum. Other spectral features of
both isomers are similar to those of 3 and suggest a
similar structure.
We have also studied the reaction of [{Rh(cod)Cl}2]
with o-diphenylphosphino(benzaldehyde) in the pres-
ence of a potentially chelating amino-imino ligand such
as 8-aminoquinoline (aqui). When using Rh:P ¼ 1:1
stoichiometric ratios, the preferred reaction is the oxi-
dative addition of PPh2(o-C6H4CHO) to give
[Rh(Cl)(H){PPh2(o-C6H4CO)} (aqui)] (7) as a mixture
of two isomers 7a and 7b, as shown in Scheme 2(i), in
ꢅ7a:7b ¼ 3:1 ratio, according to the integration of the
hydride resonances. The hydride resonances ()15.84 {t}
ppm for 7a and )15.16 {t} ppm for 7b) and the 31P{H}
NMR spectrum (74.6 {d}ppm, J(Rh,P) ¼ 168 Hz for 7a
and 73.2 {d}ppm, J(Rh,P) ¼ 166 Hz for 7b) suggest that
the hydride is trans to chlorine and the phosphorus atom
is trans to nitrogen as in 3. Although the fast decom-
position of the sample in solution precluded any NO-
ESY experiment, we have made the assignments in
Scheme 2(i) on the basis of the resonances of the amino
groups, similar to those of 3. The major isomer 7a, with
NH2 trans to phosphorus, shows two resonances at 6.00
and 5.76 ppm, while those of the minor isomer 7b, with
NH2 cis to phosphorus, appear at 4.62 and 3.68 ppm.
When the mixture [{Rh(cod)Cl}2]/aqui is allowed to
react with PPh2(o-C6H4CHO) (Rh:P ¼ 1:1) in the pres-
ence of triphenylphosphine (Rh:PPh3 ¼ 1:1) the cationic
species [Rh(H){PPh2(o-C6H4CO)}(PPh3)(aqui)]þ (8) is
formed, which has been isolated as the tetraphenylb-
orate salt, and is also a mixture of two isomers con-
taining trans phosphorus atoms as shown in Scheme
2(ii). In this complex, containing a more rigid NN li-
gand, the resonances of the amino groups of both iso-
mers appear in the high field (3–4 ppm) region due to the
ring current effects originated by the aromatic rings.
Other spectral features are as expected and the integra-
tion of the hydride resonances reveals a 8a:8b ¼ 3.5:1
ratio. A NOE effect is observed between the hydride at

2824
M.A. Garralda et al. / Inorganica Chimica Acta 357 (2004) 2818–2826
Scheme 2.
)13.24 {ddd}ppm and the NH2 resonances at 3.89 and
3.12 ppm of the major isomer 8a. It thus appears that
the hydride has a higher tendency to occupy a cis posi-
tion relative to the amino group.
The reaction of [{Rh(cod)Cl}2] with o-PPh2(o-
C6H4CHO) (Rh:P ¼ 1:2) in the presence of aqui leads
selectively to the cationic specie [Rh(H){PPh2(o-
C6H4CO)}(Paqui)]þ (9), containing the new terdentate
phosphine-diimine (Paqui) ligand (see Scheme 2(iii)),
that has been isolated as tetraphenylborate salt
[Rh(H){PPh2(o-C6H4CO)}(Paqui)]BPh4. The 13C{1H}
NMR spectrum of 9 shows the expected doublet for the
acyl group at 239.9 ppm (J(Rh,C) 110 Hz) and a singlet
at 167.1 ppm due to the new C@N bond, which corre-
lates with a resonance at 7.51 ppm due to the imino
proton, as shown by HMQC. The 31P{1H} NMR
spectrum shows two doublets of doublets corresponding
to an AMX pattern and reveals the presence of only one
isomer being formed with trans arrangement of the
phosphorus atoms shown by the J(P,P) of 352 Hz. The
1H NMR spectrum shows a hydride resonance in the
high field region ()13.66 ppm) as doublet of triplets due
to coupling constants J(Rh,H) and J(Paqui,H) of 20 Hz,
and J(P-acyl,H) of 4 Hz.
Fig. 1. ORTEP view of the cation in 3b showing the atomic numbering
(30% probability ellipsoids). The solvent molecule and the hydrogen
atoms have been omitted for clarity.
For 9 the crystal consists of [Rh(H)(PCO)(Paqui)]þ ca-
tions and BPhꢁ4 anions held together by electrostatic in-
teractions. Selected bond distances and angles are
ꢁ
The molecular structures of [Rh(H){PPh2(o-
C6H4CO)}(Pdaphen)]ClO4 ꢂ CHCl3 (3b) and [Rh(H)
{PPh2(o-C6H4CO)}(Paqui)]BPh4 ꢂ 1/2CH2Cl2 (9) are
shown in Figs. 1 and 2, respectively. For 3b the crystal
consists of [Rh(H){(PPh2(o-C6H4CO)}(Pdaphen)]þ ca-
tions and ClOꢁ4 anions held together by a hydrogen bond.
summarized in Table 2. The N1–C7 distance (1.32(2) A)
ꢁ
for 3b and the N1–C10 distance (1.27(1) A) for 9 along
with the C7–N1–C1 angle (125(2)°) for 3b and the C10–
N1–C1 angle (118.7(8)°) for 9 show the new C@N bond
formation. In both compounds the cations exhibit a
distorted octahedral geometry. The distorsion could be

M.A. Garralda et al. / Inorganica Chimica Acta 357 (2004) 2818–2826
2825
ꢁ
0.007(2) A. The dihedral angle between the N1, Rh1, C26
and the P1, P2, N2 planes is 86(1)° [22]. A careful in-
spection of the bond angles around the rhodium atom
indicates that the non-located hydride ligand must be
trans to N2 of the unreacted amino group. In compound
9, the P1, P2, N2 and H1 atoms form the equatorial plane
and the dihedral angle between this plane and the N1,
Rh1, C29 plane is also 86(1)°. The best least squares plane
C1, C2, C3, C4, C5, C6, C7, C8, N2, C9 forms an angle of
17.7° with the best least squares plane Rh1, N1, C1, C9,
N2. The N2–Rh–H1 angle (170(2)°) shows that the hy-
dride is trans to the quinolinic N2 atom. The Rh–P dis-
tances are equals within the experimental error. The Rh–
ꢁ
N1 distance (2.195(7) A), trans to acyl, and the Rh–N2
ꢁ
distance (2.175(8) A), trans to the hydride, are almost
equals in contrast with the expected slightly weaker trans
influence of the acyl ligands [23]. This can be due to N2
being the central atom of the terdentate ligand. The ob-
served Rh–P, Rh–N, Rh–C(acyl) and C@O(acyl) dis-
tances fall within reported ranges [14a,24]. In both
compounds the distances and angles for the anions and
the solvent molecules are as expected.
Fig. 2. ORTEP view of the cation in 9 showing the atomic numbering
(30% probability ellipsoids). The solvent molecule and the hydrogen
atoms, except one, have been omitted for clarity.
explained by the existence of two metallocycles of five
and six atoms that include the terdentate PNN ligand and
a third five-member metallocycle. The axial positions are
occupied by the C26 and N1 atoms in 3b and by the C29
and N1 atoms in 9. The equatorial plane in 3b is formed
by the P1, P2 and N2 atoms and the rhodium atom is
practically included in this plane with a deviation of
4. Conclusions
Rhodium(I) complexes containing chelating amino
ligands (NN) react with PPh2(o-C6H4CHO) to undergo
readily the chelate-assisted oxidative addition of alde-
Table 2
ꢁ
Selected bond lengths [A] and angles [°] for [Rh(H){PPh2(o-C6H4CO)}(Pdaphen)]ClO4 ꢂ CHCl3 (3b) and [Rh(H){PPh2(o-C6H4CO)}(Paqui)]BPh4 ꢂ 1/
2CH2Cl2 (9)
3b
9
Rh(1)–C(26)
Rh(1)–N(2)
1.92(2)
2.17(2)
2.22(2)
2.285(7)
2.265(7)
–
Rh(1)–C(29)
Rh(1)–N(2)
1.988(9)
2.175(8)
2.195(7)
2.302(2)
2.293(2)
1.59(7)
Rh(1)–N(1)
Rh(1)–P(2)
Rh(1)–N(1)
Rh(1)–P(2)
Rh(1)–P(1)
Rh(1)–H(1)
Rh(1)–P(1)
Rh(1)–H(1)
O(1)–C(26)
N(1)–C(7)
N(1)–C(1)
1.22(2)
1.32(2)
1.40(3)
96.6(9)
170.6(9)
74.5(7)
82.9(7)
97.8(5)
100.9(5)
94.5(7)
101.2(5)
84.7(5)
161.1(2)
O(1)–C(29)
N(1)–C(10)
N(1)–C(1)
1.23(1)
1.27(1)
1.43(1)
97.2(4)
C(26)–Rh(1)–N(2)
C(26)–Rh(1)–N(1)
N(2)–Rh(1)–N(1)
C(26)–Rh(1)–P(2)
N(2)–Rh(1)–P(2)
N(1)–Rh(1)–P(2)
C(26)–Rh(1)–P(1)
N(2)–Rh(1)–P(1)
N(1)–Rh(1)–P(1)
P(2)–Rh(1)–P(1)
C(29)–Rh(1)–N(2)
C(29)–Rh(1)–N(1)
N(2)–Rh(1)–N(1)
C(29)–Rh(1)–P(2)
N(2)–Rh(1)–P(2)
N(1)–Rh(1)–P(2)
C(29)–Rh(1)–P(1)
N(2)–Rh(1)–P(1)
N(1)–Rh(1)–P(1)
P(1)–Rh(1)–P(2)
C(29)–Rh(1)–H(1)
N(2)–Rh(1)–H(1)
N(1)–Rh(1)–H(1)
P(1)–Rh(1)–H(1)
P(2)–Rh(1)–H(1)
C(10)–N(1)–C(1)
171.8(4)
75.4(3)
82.7(3)
92.8(2)
101.0(2)
95.1(3)
108.1(2)
84.0(2)
159.04(9)
84(3)
170(2)
104(3)
82(2)
77(2)
C(7)–N(1)–C(1)
125(2)
118.7(7)

2826
M.A. Garralda et al. / Inorganica Chimica Acta 357 (2004) 2818–2826
[8] (a) J.C. Jeffery, T.B. Rauchfuss, P.A. Tucker, Inorg. Chem. 19
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hyde and the condensation reaction of a bonded amino
group with free aldehyde. The oxidative addition is the
preferred reaction. The condensation reaction results
in the formation of a new six-member metallocycle and
a PNN terdentate ligand. The occurrence of both
(b) T.L. Marxen, B.J. Johnson, P.V. Nilsson, L.H. Pignolet, Inorg.
Chem. 23 (1984) 4663;
(c) A.G.J. Ligtenbarg, E.K. van den Beuken, A. Meetsma, N.
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Dalton Trans. (1998) 263;
reactions
gives selectively cationic
complexes
[Rh(H){PPh2(o-C6H4CO)}(PNN)]þ containing the new
imino group cis to the hydride.
(d) J. Gao, X. Yi, P. Xu, C. Tang, H. Wan, T. Ikariya, J.
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5. Supplementary material
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1087;
Tables giving fractional coordinates and thermal pa-
rameters, bond distances and angles and observed and
calculated structure factors, can be obtained from the
authors from the Cambridge Structural Database,
Cambridge, UK, CCDC no. 221170 for compound 3b
and no. 221171 for compound 9, on request.
(b) H. Zhang, C.B. Yang, Y.Y. Li, Z.R. Donga, J.X. Gao, H.
Nakamura, K. Murata, T. Ikariya, Chem. Commun. (2003) 142.
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€
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Acknowledgements
(c) A. Bacchi, M. Carcelli, M. Costa, A. Fochi, C. Monici, P.
Pelagatti, C. Pelizzi, G. Pelizzi, L.M.S. Roca, J. Organomet.
Chem. 593–594 (2000) 180;
Partial financial supports by MCYT (Project
ꢀ
BQU2002-0129), UPV and Diputacion Foral de Gui-
puzcoa are gratefully acknowledged.
(d) W. Yeh, C. Yang, S. Peng, G. Lee, J. Chem. Soc. Dalton
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ꢀ
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