Preparation and reactivity of p-cymene complexes of ruthenium and osmium incorporating 1,3-triazenide ligands

Article abstract of DOI:10.1016/j.jorganchem.2010.05.028

p-Cymene complexes MCl₂(η⁶-p-cymene)L [M = Ru, Os; L = P(OEt)₃, PPh(OEt)₂, (CH₃) ₃CNC] were prepared by allowing [MCl(μ-Cl)(η⁶-p- cymene)]₂ to react with phosphites or tert-butyl isocyanide. Treatment of MCl₂(η⁶-p-cymene)L complexes with 1,3-ArNNN(H)Ar triazene and an excess of NEt₃ gave the cationic triazenide derivatives [M(η²-1,3-ArNNNAr)(η⁶-p- cymene)L]BPh₄ (Ar = Ph, p-tolyl). Neutral triazenide complexes MCl(η²-1,3-ArNNNAr)(η⁶-p-cymene) (M = Ru, Os) were also prepared by allowing [MCl(μ-Cl)(η⁶-p-cymene)] ₂ to react with 1,3-diaryltriazene in the presence of triethylamine. p-Cymene complexes MCl₂(η⁶-p-cymene)L reacted with equimolar amounts of 1,3-ArNNN(H)Ar triazene to give both triazenide complexes [M(η²-1,3-ArNNNAr)(η⁶-p-cymene)L]BPh₄ and amine derivatives [MCl(ArNH₂)(η⁶-p-cymene)L] BPh₄. A reaction path for the formation of the amine complex is also reported. The complexes were characterised by spectroscopy and X-ray crystallography of RuCl₂(η⁶-p-cymene)[PPh(OEt) ₂] and [Ru(η²-1,3-p-tolyl-NNN-p-tolyl) (η⁶-p-cymene){CNC(CH₃)₃}]BPh₄. Selected triazenide complexes were studied as catalysts in the hydrogenation of 2-cyclohexen-1-one and cinnamaldehyde. The preparation of triazenide complexes of ruthenium and osmium stabilised by the half-sandwich fragment [M(η⁶-p-cymene)L]⁺ with phosphite or isocyanide is described. Reaction of diaryltriazene, 1,3-ArNNN(H)Ar, toward complexes MCl ₂(η⁶-p-cymene)L leading to amine derivatives [MCl(ArNH₂)(η⁶-p-cymene)L]BPh₄ is also reported. The spectroscopic and crystallographic characterisation of new compounds, as well as their activity as catalysts in hydrogenation reactions, are also discussed.

Full text of DOI:10.1016/j.jorganchem.2010.05.028

Journal of Organometallic Chemistry 695 (2010) 2142e2152
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Preparation and reactivity of p-cymene complexes of ruthenium and osmium
incorporating 1,3-triazenide ligands
,
a
b
a
Gabriele Albertin a , Stefano Antoniutti , Jesús Castro , Stefano Paganelli
*
a Dipartimento di Chimica, Università Ca’ Foscari Venezia, Dorsoduro 2137, 30123 Venezia, Italy
b Departamento de Química Inorgánica, Universidade de Vigo, Facultade de Química, Edificio de Ciencias Experimentais, 36310 Vigo (Galicia), Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
p-Cymene complexes MCl2(
h
6-p-cymene)L [M ¼ Ru, Os; L ¼ P(OEt)3, PPh(OEt)2, (CH3)3CNC] were
prepared by allowing [MCl(
Treatment of MCl2(
gave the cationic triazenide derivatives [M(
Neutral triazenide complexes MCl(
2-1,3-ArNNNAr)(
allowing [MCl( -Cl)(
p-Cymene complexes MCl2(
triazene to give both triazenide complexes [M(
vatives [MCl(ArNH2)(
6-p-cymene)L]BPh4. A reaction path for the formation of the amine complex is also
reported. The complexes were characterised by spectroscopy and X-ray crystallography of RuCl2(
6-p-
cymene)[PPh(OEt)2] and [Ru(
2-1,3-p-tolyl-NNN-p-tolyl)( 6-p-cymene){CNC(CH3)3}]BPh4. Selected
m-Cl)(h
6-p-cymene)]2 to react with phosphites or tert-butyl isocyanide.
Received 15 April 2010
Received in revised form
27 May 2010
Accepted 28 May 2010
Available online 12 June 2010
h
6-p-cymene)L complexes with 1,3-ArN]NN(H)Ar triazene and an excess of NEt3
h
2-1,3-ArNNNAr)(
h
6-p-cymene)L]BPh4 (Ar ¼ Ph, p-tolyl).
h
h
6-p-cymene) (M ¼ Ru, Os) were also prepared by
m
h
6-p-cymene)]2 to react with 1,3-diaryltriazene in the presence of triethylamine.
h
6-p-cymene)L reacted with equimolar amounts of 1,3-ArN]NN(H)Ar
2-1,3-ArNNNAr)( 6-p-cymene)L]BPh4 and amine deri-
Dedicated to the memory of Professor
Joachim Strähle, University of Tübingen.
h
h
h
Keywords:
p-Cymene
Triazenide
Ruthenium
Osmium
h
h
h
triazenide complexes were studied as catalysts in the hydrogenation of 2-cyclohexen-1-one and
cinnamaldehyde.
Ó 2010 Elsevier B.V. All rights reserved.
Catalysis
1. Introduction
This anion is a “small-bite” ligandwhich can act asa monodentate,
chelate or bridging ligand, providing many examples of transition-
The chemistry of half-sandwich
h
6-arene complexes of ruthe-
metal complexes [10e12]. However, its use in the chemistry of half-
nium(II) and osmium(II) have been extensively developed in recent
years [1e3], due to both their interesting coordination properties
and their potential applications as precursors in catalytic reactions
[3], including hydrogen transfer [4], alkene polymerisation [5] and
olefin oxidation [6]. Ruthenium(II)-arene derivatives are also
attracting current interest for use as anticancer agents [7].
sandwich
h
6-arene complexes is practically unexplored [9], although
this bidentate N-donor ligand may potentially confer interesting
chemical and catalytic properties on this class of complexes.
We previously reported [13] the synthesis and reactivity of tri-
azene and triazenide complexes of Ru and Os of the type [M(h
2-1,3-
ArNNNAr)L4]BPh4 and [MH{
h
1-1,3-ArN]NN(H)Ar}L4]BPh4 (M ¼ Ru,
The
sandwich d6 complexes, allowing facile synthesis of a large number
of
6-arene complexes of Ru and Os containing a variety of sup-
porting ligands such as mono- and bi-dentate phosphines [2def],
aliphatic and aromatic amines [4eeg], -diketones [8a], tris(pyr-
h
6-arene molecule is very stable to the substitution in half-
Os; L ¼ phosphite) and have now extended these studies to include
half-sandwich h
6-arene complexes, with the aim of testing whether
h
triazenide ligands can be introduced into the chemistry of arene
complexes and how they can modify their chemical and catalytic
properties. The results of these studies, which allowed the synthesis
b
azolyl)borate [8bed], bis- and tris-(pyrazolyl)alkane [2a,8e],
N-heterocyclic carbene [2b,c], 1,2-bipyridine [7a], etc. However,
despite numerous studies, only a brief note on the compound RuCl
(ClC6H4N3C6H4Cl)(p-cymene) [9] has been reported on half-sand-
wich complexes containing the diaryltriazenide species [1,3-
ArNNNAr]ꢀ as a supporting ligand.
and some reactivityof unprecedentedh
6-p-cymene complexes of Ru
and Os incorporating either triazenide and phosphite or triazenide
and isocyanide mixed ligands, are reported here.
2. Experimental section
2.1. General comments
All synthetic work was carried out under Ar using standard
Schlenk techniques or an inert atmosphere dry-box. All solvents
* Corresponding author. Fax: þ39 041 2348917
E-mail address: albertin@unive.it (G. Albertin).
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.05.028

G. Albertin et al. / Journal of Organometallic Chemistry 695 (2010) 2142e2152
2143
were dried over appropriate drying agents, degassed on a vacuum
line, and distilled into vacuum-tight storage flasks. RuCl3$3H2O and
OsO4 were Pressure Chemical Co. (USA) products, used as received.
Phosphite PPh(OEt)2 was prepared by the method of Rabinowitz
and Pellon [14], while P(OEt)3 was an Aldrich product purified by
distillation under nitrogen. 1,3-Diaryltriazene 1,3-ArN]NN(H)Ar
(Ar ¼ Ph, p-tolyl) were prepared following the literature method
[15]. The labeled triazene1,3-Ph15N]N15N(H)Ph was prepared from
labeled aniline Ph15NH2 (99% enriched, CIL) and NaNO2. Other
reagents, including (CH3)3CNC, were purchased from commercial
sources in the highest available purity and used as received.
Infrared spectra (KBr pellets) were recorded on PerkineElmer
Spectrum-One FT-IR spectrophotometer. NMR spectra (1H, 31P, 13C,
15N) were obtained on AVANCE 300 Bruker spectrometer
(300 MHz) at temperatures between ꢀ90 and þ30 ꢁC, unless
otherwise noted. 1H and 13C{1H} spectra are referred to internal
tetramethylsilane; 31P{1H} chemical shifts are reported with
respect to 85% H3PO4 and 15N to CH135NO2, and in both cases
downfield shifts are considered positive. J values are given in Hz.
For the OCH2CH3 substituents of the phosphites: CH2 (multiplet),
JHH ¼ 7 Hz; CH3 (triplet), JHH ¼ 7 Hz. For p-cymene 4-CH3C6H4CH
(CH3)2: CH (multiplet), JHH ¼ 6.8 Hz; CH3 (doublet), JHH ¼ 6.8 Hz.
COSY, HMQC and HMBC NMR experiments were performed with
standard programs. The SwaNMR and iNMR software packages [16]
were used to treat NMR data. The conductivity of 10ꢀ3 mol dmꢀ3
solutions of the complexes in CH3NO2 at 25 ꢁC was measured on
a Radiometer CDM 83. Elemental analyses were determined in the
Microanalytical Laboratory of the Dipartimento di Scienze Farm-
aceutiche, University of Padova (Italy).
cym), 1.32 (t, 6H, CH3 phos), 1.16 (d, 6H, CH3 Pri) ppm. 31P{1H} NMR
(CD2Cl2, 25 ꢁC)
: 92.4 (s) ppm. C20H29Cl2O2OsP (593.55): C 40.47, H
4.92, Cl 11.95; found: C 40.32, H 5.04, Cl 11.80%.
d
2.3.2. RuCl2(h
6-p-cymene)(PPri3) (1c)
This complex was prepared exactly like the related complexes 1;
yield ꢂ90%. 1H NMR (CD2Cl2, 25 ꢁC)
d: 5.61, 5.55 (d, 4H, Ph), 2.71 (m,
4H, CH), 2.05 (s, 3H, CH3 p-cym), 1.33, 1.29, 1.27 (d, 24H, CH3 Pri)
ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC)
d: 36.7 (s) ppm. C19H35Cl2Pru
(466.43): calcd. C 48.93, H 7.56, Cl 15.20; found C 49.08, H 7.66, Cl
14.97%.
2.3.3. RuCl2(h h
6-p-cymene)(CNBut) [18] (3) and OsCl2( 6-p-cymene)
(CNBut) (4)
An excess of tert-butyl isocyanide (2.1 mmol, 0.24 mL) was
added to a solution of the appropriate dimeric complex [MCl2(
h
6-p-
cymene)]2 (M ¼ Ru, Os) (0.7 mmol) in toluene (10 mL) and the
reaction mixture was stirred at room temperature for 5 h. The
solvent was removed under reduced pressure to give an oil which
was triturated with n-hexane (8 mL). A pale yellow solid slowly
separated out which was filtered and crystallised from dichloro-
methane and hexane; yield ꢂ85%. 3: IR (KBr pellet) nCN: 2191 (s)
cmꢀ1. 1H NMR (CD2Cl2, 25 ꢁC)
d: 5.53, 5.35 (d, 4H, Ph), 2.76 (m, 1H,
CH), 2.21 (s, 3H, CH3 p-cym), 1.51 (s, 9H, CH3 But), 1.26 (d, 6H, CH3
Pri) ppm. 13C{1H} NMR (CD2Cl2, 25 ꢁC)
d: 138.5 (s, CN), 107.8, 106.4,
87.7, 87.5 (s, Ph p-cym), 58.6 (s, C But), 31.5 (s, CH), 30.6 (s, CH3 But),
22.4 (s, CH3 Pri), 18.7 (s, CH3 p-cym) ppm. C15H23Cl2NRu (389.33):
calcd. C 46.27, H 5.95, Cl 18.21, N 3.60; found C 46.33, H 5.83, Cl
18.09, N 3.73%. 4: IR (KBr pellet) nCN: 2185 (s) cmꢀ1. 1H NMR (CD2Cl2,
25 ꢁC)
d: 5.65, 5.45 (d, 4H, Ph), 2.73 (m, 1H, CH), 2.28 (s, 3H, CH3 p-
2.2. Synthesis of precursor complexes
cym), 1.53 (s, 9H, CH3 But), 1.27 (d, 6H, CH3 Pri) ppm. C15H23Cl2NOs
(478.49): C 37.65, H 4.84, Cl 14.82, N 2.93; found C 37.74, H 4.92, Cl
14.68, N 2.99%.
Complexes [RuCl2(h h
6-p-cymene)]2 and [OsCl2( 6-p-cymene)]2
were prepared following the previously reported methods [17].
2.3.4. [Ru(
h
2-1,3-ArNNNAr)(
h
6-p-cymene)L]BPh4 (5, 6) [Ar ¼ Ph
2.3. Synthesis of complexes
(5), p-tolyl (6); [L ¼ P(OEt)3 (a), PPh(OEt)2 (b)]
In a 25-mL three-necked round-bottomed flask were placed
2.3.1. RuCl2(
(OEt)3 (a), PPh(OEt)2 (b)]
h
6-p-cymene)L (1) and OsCl2(
h
6-p-cymene)L (2) [L ¼ P
solid samples of the complex RuCl2(h
6-p-cymene)L (1)
(0.4 mmol), of the appropriate 1,3-diaryltriazene (0.5 mmol), of
the salt NaBPh4 (0.82 mmol, 0.28 g) and 6 mL of ethanol. An
excess of triethylamine (4.0 mmol, 0.55 mL) was added to the
resulting suspension, which was stirred for 12 h. An orange solid
separated out from the reaction mixture which was filtered and
crystallised from dichloromethane and ethanol; yield ꢂ80%. 5b:
An excess of the appropriate phosphite (3.5 mmol) was added to
a solution of the dimeric complex [MCl2(
h
6-p-cymene)]2 (M ¼ Ru,
Os) (0.7 mmol) in CH2Cl2 (10 mL) and the reaction mixture was
stirred at room temperature for 3 h. The solvent was removed
under reduced pressure to give an oil which was triturated with
n-hexane (10 mL). A yellow solid slowly separated out which was
filtered and crystallised from dichloromethane and hexane; yield:
1H NMR (CD2Cl2, 25 ꢁC)
d: 7.35e6.89 (m, 35H, Ph), 5.96, 5.50 (d,
4H, Ph p-cym), 3.88 (m, 4H, CH2), 2.73 (m, 1H, CH), 2.16 (s, 3H,
ꢂ90%. 1a: 1H NMR (CD2Cl2, 25 ꢁC)
d: 5.50, 5.24 (d, 4H, Ph), 4.11 (qnt,
6H, CH2), 2.83 (m, 1H, CH), 2.10 (s, 3H, CH3 p-cym), 1.27 (t, 9H, CH3
CH3 p-cym), 1.19 (d, 6H, CH3 Pri), 1.18 (t, 6H, CH3 phos) ppm. 31P
{1H}
NMR
(CD2Cl2,
25
ꢁC)
d:
148.1
(s)
ppm.
phos), 1.21 (d, 6H, CH3 Pri) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC)
114.2 (s) ppm. C16H29Cl2O3PRu (472.35): calcd. C 40.68, H 6.19, Cl
15.01; found C 40.46, H 6.11, Cl 14.88%.1b: 1H NMR (CD2Cl2, 25 ꢁC)
d
:
L
¼ 53.8 Uꢀ1 molꢀ1 cm2. C56H59BN3O2PRu (948.94): calcd. C
M
70.88, H 6.27, N 4.43; found C 70.67, H 6.38, N 4.30%. 6a: 1H
d:
NMR (CD2Cl2, 25 ꢁC)
d: 7.36e6.89 (m, 28H, Ph), 5.91, 5.49 (d, 4H,
7.75, 7.45 (m, 5H, Ph phos), 5.33, 5.24 (d, 4H, Ph p-cym), 4.16, 4.04
(m, 4H, CH2), 2.68 (m, 1H, CH), 1.91 (s, 3H, CH3 p-cym), 1.32 (t, 6H,
Ph p-cym), 3.85 (m, 6H, CH2), 2.65 (m, 1H, CH), 2.36 (s, 6H, CH3
p-tol), 2.19 (s, 3H, CH3 p-cym), 1.17 (d, 6H, CH3 Pri), 1.12 (t, 9H,
CH3 phos), 1.09 (d, 6H, CH3 Pri) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC)
d
:
CH3 phos) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC)
d: 117.6 (s) ppm.
138.2 (s) ppm. 13C{1H} NMR (CD2Cl2, 25 ꢁC)
d
: 138e128 (m, Ph
13C{1H} NMR (CD2Cl2, 25 ꢁC)
d: 165e187 (m, Ph), 64.6 (d, CH2),
phos), 108.9, 98.9, 90.9, 88.8 (s, Ph p-cym), 64.4 (d, CH2), 30.5 (s,
CH), 21.9 (s, CH3 Pri), 17.9 (s, CH3 p-cym), 16.4 (d, CH3 phos) ppm.
C20H29Cl2O2PRu (504.39): calcd. C 47.62, H 5.80, Cl 14.06; found C
32.4 (s, CH), 22.6 (s, CH3 Pri), 21.0 (s, CH3 p-tol), 19.6 (s, CH3 p-
cym), 16.0 (d, CH3 phos) ppm. L ¼ 51.7 Uꢀ1 molꢀ1 cm2.
M
C54H63BN3O3PRu (944.95): calcd. C 68.64, H 6.72, N 4.45; found
47.48, H 5.72, Cl 14.23%. 2a: 1H NMR (CD2Cl2, 25 ꢁC)
d
: 5.64, 5.50 (d,
C 68.73, H 6.63, N 4.34%. 6b: 1H NMR (CD2Cl2, 25 ꢁC)
d:
4H, Ph), 4.12 (qnt, 6H, CH2), 2.82 (m, 1H, CH), 2.22 (s, 3H, CH3 p-
7.35e6.82 (m, 33H, Ph), 5.96, 5.46 (d, 4H, Ph p-cym), 3.87 (m,
4H, CH2), 2.73 (m, 1H, CH), 2.37 (s, 6H, CH3 p-tol), 2.14 (s, 3H,
CH3 p-cym), 1.20 (t, 6H, CH3 phos), 1.18 (d, 6H, CH3 Pri) ppm. 31P
cym), 1.29 (t, 9H, CH3 phos), 1.26 (d, 6H, CH3 Pri) ppm. 31P{1H} NMR
(CD2Cl2, 25 ꢁC)
d
: 69.5 (s) ppm. C16H29Cl2O3OsP (561.51): calcd. C
34.22, H 5.21, Cl 12.63; found C 34.11, H 5.30, Cl 12.78%. 2b: 1H NMR
(CD2Cl2, 25 ꢁC)
: 7.65, 7.43 (m, 5H, Ph phos), 5.51, 5.39 (d, 4H, Ph p-
cym), 4.10, 3.96 (m, 4H, CH2), 2.64 (m, 1H, CH), 2.06 (s, 3H, CH3 p-
{1H}
NMR
(CD2Cl2,
25
ꢁC)
d
:
148.2
(s)
ppm.
d
L
M
¼ 55.2 Uꢀ1 molꢀ1 cm2. C58H63BN3O2PRu (976.99): calcd. C
71.30, H 6.50, N 4.30; found C 71.14, H 6.62, N 4.18%.

2144
G. Albertin et al. / Journal of Organometallic Chemistry 695 (2010) 2142e2152
2.3.5. [Ru(
(6c)
h
2-1,3-p-tolyl-NNN-p-tolyl)(
h
6-p-cymene)(PPri3)]BPh4
22.9 (s, CH3 Pri), 20.0 (s, CH3 p-cym) ppm. L ¼ 58.6 Uꢀ1 molꢀ1 cm2.
M
C51H53BN4Ru (833.87): calcd. C 73.46, H 6.41, N 6.72; found C 73.29,
This complex was prepared exactly like the related complexes 5,
H 6.54, N 6.60%. 10: IR (KBr pellet) nCN: 2191 (s) cmꢀ1 1H NMR
.
6; yield ꢂ80%. 1H NMR (CD2Cl2, 25 ꢁC)
d
: 7.34e6.84 (m, 28H, Ph),
(CD2Cl2, 25 ꢁC)
d: 7.37e6.86 (m, 28H, Ph), 5.79, 5.42 (d, 4H, Ph
6.01, 5.40 (d, 4H, Ph p-cym), 2.65 (m, 4H, CH), 2.36 (s, 6H, CH3 p-tol),
2.11 (s, 3H, CH3 p-cym), 1.17, 1.13, 1.12 (d, 24H, CH3 Pri) ppm. 31P{1H}
p-cym), 2.66 (m, 1H, CH), 2.37 (s, 6H, CH3 p-tol), 2.13 (s, 3H, CH3
p-cym), 1.29 (s, 9H, CH3 But), 1.22 (d, 6H, CH3 Pri) ppm.
NMR (CD2Cl2, 25 ꢁC)
d
: 49.2 (s) ppm. L ¼ 56.5 Uꢀ1 molꢀ1 cm2.
L
¼ 55.6 Uꢀ1 molꢀ1 cm2. C53H57BN4Ru (861.93): calcd. C 73.85, H
M
M
C57H69BN3PRu (939.03): calcd. C 72.91, H 7.41, N 4.47; found C
72.72, H 7.52, N 4.36%.
6.67, N 6.50; found C 73.66, H 6.55, N 6.38%. 11: IR (KBr pellet) nCN:
2181 (s) cmꢀ1 1H NMR (CD2Cl2, 25 ꢁC)
. d: 7.41e6.86 (m, 30H, Ph),
6.00, 5.63 (d, 4H, Ph p-cym), 2.63 (m, 1H, CH), 2.31 (s, 3H, CH3
2.3.6. [Os(
h
2-1,3-ArNNNAr)(
h
6-p-cymene)L]BPh4 (7, 8) [Ar ¼ Ph
p-cym), 1.30 (s, 9H, CH3 But), 1.19 (d, 6H, CH3 Pri) ppm.
(7), p-tolyl (8); L ¼ P(OEt)3 (a), PPh(OEt)2 (b)]
L
¼ 56.5 Uꢀ1 molꢀ1 cm2. C51H53BN4Os (923.03): calcd. C 66.36, H
M
These complexes were prepared like the related ruthenium
derivatives 5, 6, but using a reaction time of 24 h; yield ꢂ85%. 7a: 1H
5.79, N 6.07; found C 66.47, H 5.66, N 6.15%. 12: IR (KBr pellet) nCN:
2183 (m) cmꢀ1. 1H NMR (CD2Cl2, 25 ꢁC)
d: 7.35e6.86 (m, 28H, Ph),
NMR (CD2Cl2, 25 ꢁC)
d: 7.38e6.86 (m, 30H, Ph), 6.03, 5.69 (d, 4H, Ph
5.97, 5.60 (d, 4H, Ph p-cym), 2.62 (m, 1H, CH), 2.37 (s, 6H, CH3 p-tol),
p-cym), 3.84 (qnt, 6H, CH2), 2.60 (m, 1H, CH), 2.39 (s, 3H, CH3
2.29 (s, 3H, CH3 p-cym), 1.30 (s, 9H, CH3 But), 1.18 (d, 6H, CH3 Pri)
p-cym), 1.13 (d, 6H, CH3 Pri), 1.08 (t, 9H, CH3 phos) ppm. 31P{1H}
ppm. 13C{1H} NMR (CD2Cl2, 25 ꢁC)
d: 165e116 (m, Ph), 136.6 (s, CN),
NMR (CD2Cl2, 25 ꢁC)
d
: 75.7 (s) ppm. L ¼54.9 Uꢀ1 molꢀ1 cm2.
100.8, 100.6, 82.4, 78.8 (s, Ph p-cym), 60.1 (s, C But), 32.5 (s, CH),
30.6 (s, CH3 But), 23.2 (s, CH3 Pri), 21.0 (s, CH3 p-tol), 19.7 (s, CH3 p-
M
C52H59BN3O3OsP (1006.06): calcd. C 62.08, H 5.91, N 4.18; found C
62.23, H 5.80, N 4.06%. 7b: 1H NMR (CD2Cl2, 25 ꢁC)
d
: 7.34e6.87 (m,
cym) ppm. L ¼ 53.1 Uꢀ1 molꢀ1 cm2. C53H57BN4Os (951.09): calcd.
M
35H, Ph), 6.07, 5.71 (d, 4H, Ph p-cym), 3.86 (m, 4H, CH2), 2.67 (m,1H,
CH), 2.38 (s, 3H, CH3 p-cym), 1.18 (t, 6H, CH3 phos), 1.14 (d, 6H, CH3
C 66.93, H 6.04, N 5.89; found C 66.71, H 5.93, N 5.98%.
Pri) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC)
d:
105.8 (s) ppm.
2.3.9. [Os(h h
2-1,3-Ph15NN15NPh)( 6-p-cymene)(CNBut)]BPh4 (11*)
L
¼ 56.5 Uꢀ1 molꢀ1 cm2. C56H59BN3O2OsP (1038.10): calcd. C
This complex was prepared exactly like the related unlabeled
M
64.79, H 5.73, N 4.05; found C 64.56, H 5.86, N 3.93%. 8a: 1H NMR
compound 11 by using 1,3-Ph15N]N15N(H)Ph as a reagent; yield
(CD2Cl2, 25 ꢁC)
d: 7.34e6.87 (m, 28H, Ph), 6.00, 5.64 (d, 4H, Ph
ꢂ75%. IR (KBr pellet) nCN: 2179 (s) cmꢀ1. 1H NMR (CD2Cl2, 25 ꢁC)
d:
p-cym), 3.83 (m, 6H, CH2), 2.60 (m, 1H, CH), 2.37 (s, 3H, CH3 p-cym),
7.40e6.86 (m, 30H, Ph), 6.01, 5.65 (d, 4H, Ph p-cym), 2.63 (m, 1H,
2.36 (s, 6H, CH3 p-tol), 1.12 (t, 9H, CH3 phos), 1.08 (d, 6H, CH3 Pri)
CH), 2.31 (s, 3H, CH3 p-cym), 1.30 (s, 9H, CH3 But), 1.18 (d, 6H, CH3
ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC)
d:
76.3 (s) ppm.
Pri) ppm. 15N{1H} NMR (CD2Cl2, 25 ꢁC)
d: X2 spin syst, dx
L
¼ 51.8 Uꢀ1 molꢀ1 cm2. C54H63BN3O3OsP (1034.11): calcd. C
ꢀ186.9 ppm.
M
62.72, H 6.14, N 4.06; found C 62.55, H 6.27, N 4.19%. 8b: 1H NMR
(CD2Cl2, 25 ꢁC)
d: 7.35e6.87 (m, 33H, Ph), 6.05, 5.66 (d, 4H, Ph
2.3.10. RuCl(
p-tolyl (14)] and OsCl(
(15)
h
2-1,3-ArNNNAr)(
h
6-p-cymene) (13, 14) [Ar ¼ Ph (13),
p-cym), 3.84 (m, 4H, CH2), 2.67 (m, 1H, CH), 2.36 (s, 3H, CH3 p-cym),
h h
2-1,3-p-tolyl-NNN-p-tolyl)( 6-p-cymene)
2.35 (s, 6H, CH3 p-tol), 1.18 (t, 6H, CH3 phos), 1.13 (d, 6H, CH3 Pri)
ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC)
d
:
106.0 (s)ppm.
In a 25-mL three-necked round-bottomed flask were placed
L
¼ 54.4 Uꢀ1 molꢀ1 cm2. C58H63BN3O2OsP (1066.15): calcd. C
solid samples of the appropriate dimeric complex [MCl2(
h
6-p-
M
65.34, H 5.96, N 3.94; found C 65.13, H 6.06, N 3.81%.
cymene)]2 (M ¼ Ru, Os) (0.3 mmol), a slight excess of 1,3-dia-
ryltriazene (0.7 mmol) and 10 mL of toluene. An excess of
triethylamine (3 mmol, 0.42 mL) was added to the resulting
solution, which was stirred for 24 h. The solvent was removed
under reduced pressure to give an oil which was triturated with
n-hexane. An orange solid slowly separated out which was
filtered and crystallised from dichloromethane and ethanol;
2.3.7. [Os(h h
2-1,3-Ph15NN15NPh)( 6-p-cymene){PPh(OEt)2}]BPh4
(7b*)
This complex was prepared exactly like the related unlabeled
compound 7b by using 1,3-Ph15N]N15N(H)Ph as a reagent; yield
ꢂ70%. 1H NMR (CD2Cl2, 25 ꢁC)
d: 7.36e6.88 (m, 35H, Ph), 6.06, 5.70
(d, 4H, Ph p-cym), 3.85 (m, 4H, CH2), 2.67 (m, 1H, CH), 2.37 (s, 3H,
yield ꢂ85%. 13: 1H NMR (CD2Cl2, 25 ꢁC)
d: 7.32, 7.10 (m, 10H,
CH3 p-cym), 1.18 (t, 6H, CH3 phos), 1.14 (d, 6H, CH3 Pri) ppm. 31P{1H}
Ph), 5.80, 5.38 (d, 4H, Ph p-cym), 2.74 (m, 1H, CH), 2.30 (s, 6H,
CH3 Pri), 1.20 (d, 3H, CH3 p-cym) ppm. C22H24ClN3Ru (466.97):
calcd. C 56.59, H 5.18, Cl 7.59, N 9.00; found C 56.44, H 5.27, Cl
NMR (CD2Cl2, 25 ꢁC)
d
: AX2 spin syst (X ¼ 15N), dA 105.9 ppm, JAx
5.2 Hz. 15N{1H} NMR (CD2Cl2, 25 ꢁC)
d
: X2A spin syst (A ¼ 31P), dx
ꢀ188.9 ppm, JxA 5.2 Hz.
7.45, N 9.13%. 14: 1H NMR (CD2Cl2, 25 ꢁC)
d: 7.20e7.12 (m, 8H,
Ph), 5.79, 5.36 (d, 4H, Ph p-cym), 2.74 (m, 1H, CH), 2.34 (s, 6H,
CH3 p-tol), 2.29 (s, 6H, CH3 Pri), 1.21 (d, 3H, CH3 p-cym) ppm.
C24H28ClN3Ru (495.02): calcd. C 58.23, H 5.70, Cl 7.16, N 8.49;
found C 58.40, H 5.82, Cl 7.01, N 8.58%. 15: 1H NMR (CD2Cl2,
2.3.8. [M(h h
2-1,3-ArNNNAr)( 6-p-cymene)(CNBut)]BPh4 (9e12)
[M ¼ Ru (9, 10), Os (11, 12); Ar ¼ Ph (9, 11), p-tolyl (10, 12)]
In a 25-mL three-necked round-bottomed flask were placed
solid samples of the complex MCl2(
h
6-p-cymene)(CNBut) (3, 4)
25 ꢁC)
d
: 7.38e6.90 (8H, m, Ph), 6.14, 5.62 (4H, d, Ph p-cym),
2.59 (1H, m, CH), 2.36 (3H, s, CH3 p-cym), 2.34 (6H, s, CH3 p-tol),
1.13 (6H, d, CH3 Pri) ppm. 13C{1H} NMR (CD2Cl2, 25 ꢁC)
: 144.2,
(M ¼ Ru, Os) (0.2 mmol), a slight excess of the appropriate 1,3-
diaryltriazene (0.24 mmol), an excess of solid NaBPh4 (0.40 mmol,
137 mg) and 5 mL of ethanol. An excess of triethylamine (2.4 mmol,
0.33 mL) was added to the resulting suspension, which was stirred
for 12 h, in the case of ruthenium, or 24 h, for osmium. The yellow
solid that separated out was filtered and crystallised from
d
134.5, 129.8, 116.8 (s, Ph), 97.3, 94.2, 73.1, 69.0 (s, Ph p-cym),
32.6 (s, CH), 23.1 (s, CH3 Pri), 21.0 (s, CH3 p-tol), 19.2 (s, CH3 p-
cym) ppm. C24H28ClN3Os (584.18): calcd. C 49.34, H 4.83, Cl 6.07,
N 7.19; found C 49.15, H 4.71, Cl 6.26, N 7.03%.
dichloromethane and ethanol; yield ꢂ80%. 9: IR (KBr pellet) nCN
:
2189 (s) cmꢀ1. 1H NMR (CD2Cl2, 25 ꢁC)
d
: 7.39e6.89 (m, 30H, Ph),
2.3.11. [MCl(ArNH2)(
h
6-p-cymene)L]BPh4 (16e19) [M ¼ Ru (16, 17),
5.81, 5.44 (d, 4H, Ph p-cym), 2.66 (m, 1H, CH), 2.14 (s, 3H, CH3 p-
Os (18, 19); Ar ¼ Ph (16, 18), p-tolyl (17, 19); L ¼ P(OEt)3 (a), PPh
cym), 1.28 (s, 9H, CH3 But), 1.23 (d, 6H, CH3 Pri) ppm. 13C{1H} NMR
(OEt)2 (b)]
(CD2Cl2, 25 ꢁC)
d
: 165e116 (m, Ph), 142.5 (s, br, CN), 113.9, 107.5,
In a 25-mL three-necked round-bottomed flask were placed
89.4, 86.6 (s, Ph p-cym), 60.1 (s, C But), 32.5 (s, CH), 30.3 (s, CH3 But),
solid samples of the appropriate complex MCl2(h
6-p-cymene)L (1,

G. Albertin et al. / Journal of Organometallic Chemistry 695 (2010) 2142e2152
2145
31
2) (M ¼ Ru, Os) (0.2 mmol), an equimolar amount of 1,3-diary-
(d, 6H, CH3 Pri) ppm. P{1H} NMR (CD2Cl2, 25 ꢁC)
d
: AX spin syst
ltriazene (0.2 mmol), an equimolar amount of NaBPh4 (0.2 mmol,
68 mg) and 5 mL of ethanol. The reaction mixture was stirred for
24 h and the yellow solid which separated out was filtered and
dried under vacuum. The amine complex was separated from the
mixture by fractional crystallisation from þ20 to ꢀ20 ꢁC using
a mixture of CH2Cl2 and ethanol as solvent. The first separated
(X ¼ 15N), dA 144.8 ppm, JAx 3.9 Hz. 15N NMR (CD2Cl2, 25 ꢁC)
d: XAY2
spin syst (A ¼ 31P, Y ¼ 1H), dx ꢀ366.6 ppm, JAx 3.9, JxY 72.8 Hz. 18b*:
IR (KBr pellet) n15NH: 3260, 3215 (m) cmꢀ1. 1H NMR (CD2Cl2, 25 ꢁC)
d
: 7.63e6.86 (m, 25H, Ph), 5.25, 4.63 (ddd, 2H, NH2), 5.52, 5.28, 5.13,
5.06 (d, 4H, Ph p-cym), 5.43e5.10 (m, 5H, Ph amine), 4.11, 3.95 (m,
4H, CH2), 2.58 (m, 1H, CH), 2.05 (s, 3H, CH3 p-cym), 1.44, 1.43 (t, 6H,
CH3 phos), 1.18, 1.16 (d, 6H, CH3 Pri) ppm. 31P{1H} NMR (CD2Cl2,
products contained mainly the compounds [M(
6-p-cymene)L]BPh4, while the third fraction contained the amine
derivatives 16e19; yield ꢂ20%. 16b: IR (KBr pellet) nNH: 3293, 3216
(m) cmꢀ1. 1H NMR (CD2Cl2, 25 ꢁC)
: 7.90e6.86 (m, 25H, Ph), 5.40,
h
2-1,3-ArNNNAr)
(h
25 ꢁC)
d
: AX spin syst (X ¼ 15N), dA 100.2 ppm, JAx 2.7 Hz. 15N NMR
(CD2Cl2, 25 ꢁC)
2.7, JxY 72.9 Hz.
d
: XAY2 spin syst (A ¼ 31P, Y ¼ 1H), dx ꢀ377.4 ppm, JxA
d
4.48 (br d, 2H, NH2), 5.34, 5.18 (m, 5H, Ph amine), 5.25, 5.14, 4.80,
4.77 (d, 4H, Ph p-cym), 4.14, 4.06 (m, 4H, CH2), 2.57 (m, 1H, CH), 1.88
(s, 3H, CH3 p-cym), 1.48, 1.46 (t, 6H, CH3 phos), 1.11, 1.09 (d, 6H, CH3
2.3.13. [OsCl(ArNH2)(
(20), p-tolyl (21)]
These complexes were prepared exactly like the related phos-
phite complexes 18, 19 by using OsCl2(
6-p-cymene)(CNBut) (4) as
a precursor; yield ꢂ25%. 20: IR (KBr pellet): nNH 3256, 3206 (m); nCN
2178 (s) cmꢀ1. 1H NMR (CD2Cl2, 25 ꢁC)
: 7.35e6.72 (m, 20H, Ph),
h
6-p-cymene)(CNBut)]BPh4 (20, 21) [Ar ¼ Ph
Pri) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC)
d
:
144.7 (s) ppm.
L
¼ 54.3 Uꢀ1 molꢀ1 cm2. C50H56BClNO2PRu (881.29): calcd. C
h
M
68.14, H 6.40, Cl 4.02, N 1.59; found C 67.96, H 6.53, Cl 3.91, N 1.68%.
17a: IR (KBr pellet) nNH: 3289, 3215 (m) cmꢀ1
.
1H NMR (CD2Cl2,
d
25 ꢁC)
d
: 7.34e6.88 (m, 24H, Ph), 5.34, 5.30, 4.80, 4.68 (d, 4H, Ph p-
5.61, 4.63 (br d, 2H, NH2), 5.32e5.04 (m, 9H, Ph amine þ p-cym),
cym), 4.75 (br, 2H, NH2), 4.23 (m, 6H, CH2), 2.64 (m, 1H, CH), 2.38 (s,
2.45 (m, 1H, CH), 2.11 (s, 3H, CH3 p-cym), 1.33 (s, 9H, CH3 But), 1.19,
3H, CH3 p-tol),1.97 (d, 6H, CH3 Pri),1.39 (t, 9H, CH3 phos),1.16 (d, 3H,
1.16 (d, 6H, CH3 Pri) ppm. L ¼ 55.9 Uꢀ1 molꢀ1 cm2. C45H50BClN2Os
M
CH3 p-cym) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC)
d
: 114.0 (s) ppm.
(855.39): calcd. C 63.19, H 5.89, Cl 4.14, N 3.27; found C 63.33, H
L
M
¼ 57.2 Uꢀ1 molꢀ1 cm2. C47H58BClNO3PRu (863.28): calcd. C
5.76, Cl 4.32, N 3.18%. 21: IR (KBr pellet): nNH 3256, 3193 (m); nCN
65.39, H 6.77, Cl 4.11, N 1.62; found C 65.16, H 6.91, Cl 3.94, N 1.70%.
2174 (s) cmꢀ1 1H NMR (CD2Cl2, 25 ꢁC)
. d: 7.35e6.65 (m, 20H, Ph),
17b: IR (KBr pellet) nNH: 3318, 3237 (m) cmꢀ1
.
1H NMR (CD2Cl2,
5.98, 5.61 (d, 4H, Ph amine), 5.75, 4.74 (br d, 2H, NH2), 5.26e5.07
(m, 4H, Ph p-cym), 2.48 (m, 1H, CH), 2.30 (s, 3H, CH3 p-tol), 2.10 (s,
3H, CH3 p-cym), 1.34 (s, 9H, CH3 But), 1.17, 1.11 (d, 6H, CH3 Pri) ppm.
25 ꢁC)
d
: 7.64e6.85 (m, 25H, Ph), 5.97, 5.47 (d, 4H, Ph amine), 5.28,
5.13, 4.79, 4.75 (d, 4H, Ph p-cym), 5.30, 4.42 (br d, 2H, NH2), 4.05,
3.85 (m, 4H, CH2), 2.61 (m, 1H, CH), 2.35 (m, 3H, CH3 p-tol), 1.87 (s,
13C{1H} NMR (CD2Cl2, 25 ꢁC)
d: 165e116 (m, Ph), 106.7, 100.8, 82.4,
3H, CH3 p-cym), 1.46, 1.45 (t, 6H, CH3 phos), 1.13, 1.10 (d, 6H, CH3 Pri)
78.8 (s, Ph amine), 103.9, 98.1, 78.1, 76.0 (s, Ph p-cym), 102.4 (s, CN),
31
ppm. P{1H} NMR (CD2Cl2, 25 ꢁC)
d
: 145.1 (s) ppm. 13C{1H} NMR
59.4 (s, C But), 31.9 (s, CH), 30.5 (s, CH3 But), 23.2 (s, CH3 Pri), 21.5 (s,
(CD2Cl2, 25 ꢁC)
d: 165e116.5 (m, Ph), 118.1, 105.9, 88.2, 87.5 (s, Ph
CH3 p-tol), 18.2 (s, CH3 p-cym) ppm. L ¼ 54.4 Uꢀ1 molꢀ1 cm2.
M
amine), 116.1, 105.6, 92.5, 90.0, 88.3, 84.6 (s, Ph p-cym), 66.3, 65.2 (s,
C46H52BClN2Os (869.41): calcd. C 63.55, H 6.03, Cl 4.08, N 3.22;
found C 63.34, H 6.15, Cl 3.92, N 3.29%.
CH2), 30.9 (s, CH), 22.4, 22.0 (s, CH3 Pri), 21.1 (s, CH3 p-tol), 21.0 (s,
CH3 p-cym), 16.4 (m, CH3 phos) ppm. L ¼ 58.6 Uꢀ1 molꢀ1 cm2.
M
C51H58BClNO2PRu (895.32): calcd. C 68.42, H 6.53, Cl 3.96, N 1.56;
2.3.14. [OsCl(Ph15NH2)( 6-p-cymene)(CNBut)]BPh4 (20*)
h
found C 68.22, H 6.67, Cl 4.14, N 1.43%.18b: IR (KBr pellet) nNH: 3273,
This complex was prepared exactly like the related unlabeled
3220 (m) cmꢀ1. 1H NMR (CD2Cl2, 25 ꢁC)
d: 7.68e6.86 (m, 25H, Ph),
compound 20 by using 1,3-Ph15N]N15N(H)Ph as a reagent; yield
5.25, 4.64 (br d, 2H, NH2), 5.53, 5.27, 5.13, 5.06 (d, 4H, Ph p-cym),
5.40e5.10 (m, 5H, Ph amine), 4.10, 3.95 (m, 4H, CH2), 2.56 (m, 1H,
CH), 2.05 (s, 3H, CH3 p-cym), 1.43, 1.42 (t, 6H, CH3 phos), 1.18, 1.16 (d,
ꢂ20%. IR (KBr pellet): n15 3246, 3203 (m); nCN 2178 (s) cmꢀ1. 1H
NH
NMR (CD2Cl2, 25 ꢁC)
d: 7.36e6.73 (m, 20H, Ph), 5.61, 4.63 (dd, 2H,
NH2), 5.30e5.03 (m, 9H, Ph amine þ p-cym), 2.45 (m, 1H, CH), 2.11
6H, CH3 Pri) ppm. 31P{1H} NMR (CD2Cl2, 25 ꢁC)
d: 105.8 (s) ppm.
(s, 3H, CH3 p-cym), 1.33 (s, 9H, CH3 But), 1.19, 1.16 (d, 6H, CH3 Pri)
L
¼ 55.7 Uꢀ1 molꢀ1 cm2. C50H56BClNO2OsP (970.45): calcd. C
ppm. 15N{1H} NMR (CD2Cl2, 25 ꢁC)
d
: ꢀ387.6 (s) ppm.
M
61.88, H 5.82, Cl 3.65, N 1.44; found C 61.75, H 5.68, Cl 3.83, N 1.31%.
19b: IR (KBr pellet) nNH: 3269, 3218 (m) cmꢀ1
.
1H NMR (CD2Cl2,
2.4. Crystal structure determination
25 ꢁC)
d: 7.62e6.88 (m, 25H, Ph), 6.05, 5.65 (d, 4H, Ph amine), 5.30,
5.13, 5.11, 5.03 (d, 4H, Ph p-cym), 5.22, 4.56 (br d, 2H, NH2), 4.11, 3.99
(m, 4H, CH2), 2.59 (m, 1H, CH), 2.37 (m, 3H, CH3 p-tol), 2.00 (s, 3H,
Crystallographic data were collected for 10 on a Bruker Smart
1000 CCD diffractometer at CACTI (Universidade de Vigo) and for 1b
on Bruker SMART APEX 2 CCD diffractometer at RIAIDT-CACTUS
CH3 p-cym), 1.44, 1.43 (t, 6H, CH3 phos), 1.27, 1.17 (d, 6H, CH3 Pri)
31
ppm. P{1H} NMR (CD2Cl2, 25 ꢁC)
d
: 100.4 (s) ppm. 13C{1H} NMR
(Universidade de Santiago de Compostela) using graphite mono-
(CD2Cl2, 25 ꢁC)
d
: 165e116 (m, Ph), 112.0, 98.5, 81.8, 79.6 (s, Ph
chromated Mo-K
a
radiation (
l
¼ 0.71073 A), and were corrected for
ꢀ
amine), 109.9, 101.1, 84.5, 81.7, 77.9, 75.2 (s, Ph p-cym), 65.6, 64.8 (s,
Lorentz and polarisation effects. The software SMART [19] and
SAINT [20] (10) or APEX2 [21] (1b) was used for collecting frames of
data, indexing reflections, determination of lattice parameters,
integration of intensity of reflections and scaling, and SADABS [22]
for empirical absorption correction. Both structures were solved
and refined with the Oscail program [23] by Patterson (10) or by
direct (1b) methods and refined by a full-matrix least-squares
based on F2 [24]. Non-hydrogen atoms were refined with aniso-
tropic displacement parameters. Hydrogen atoms were included in
idealised positions and refined with isotropic displacement
parameters. Details of crystal data and structural refinement are
given in Table 1. CCDC 762672 and 762673 contain the supple-
mentary crystallographic data for this paper. These data can be
obtained free of charge at www.ccdc.cam.ac.uk/conts/retrieving.
html.
CH2), 30.7 (s, CH), 22.6, 22.1 (s, CH3 Pri), 20.9 (s, CH3 p-cym), 18.4 (s,
CH3 p-tol), 16.3 (m, CH3 phos) ppm. L ¼ 56.9 Uꢀ1 molꢀ1 cm2.
M
C51H58BClNO2OsP (984.48): calcd. C 62.22, H 5.94, Cl 3.60, N 1.42;
found C 62.00, H 5.82, Cl 3.77, N 1.54%.
2.3.12. [RuCl(Ph15NH2)(
h
6-p-cymene){PPh(OEt)2}]BPh4 (16b*)
[OsCl(Ph15NH2)( 6-p-cymene)-{PPh(OEt)2}]BPh4 (18b*)
h
These complexes were prepared exactly like the related unla-
beled compounds 16b and 18b by using 1,3-Ph15N]N15N(H)Ph as
a reagent; yield ꢂ18%. 16b*: IR (KBr pellet) n1N5H: 3288, 3212 (m)
cmꢀ1. 1H NMR (CD2Cl2, 25 ꢁC)
d: 7.90e6.86 (m, 25H, Ph), 5.38, 4.49
(ddd, 2H, NH2, J151 72.8 Hz), 5.34, 5.18 (m, 5H, Ph amine), 5.25,
NH
5.13, 4.78, 4.76 (d, 4H, Ph p-cym), 4.14, 4.08 (m, 4H, CH2), 2.59 (m,
1H, CH), 1.87 (s, 3H, CH3 p-cym), 1.47, 1.46 (t, 6H, CH3 phos), 1.11, 1.08

2146
G. Albertin et al. / Journal of Organometallic Chemistry 695 (2010) 2142e2152
2.5. General procedure for the hydrogenation experiments
formed under reaction conditions [25e28]. Visual homogeneity of
the solution is not enough to assess the absence of suspended or
colloidal metal, therefore we carried out some hydrogenation
experiments in the presence of Hg(0), according to a procedure
described in the literature [28]. It is known that Hg(0) is able to
poison metal(0) heterogeneous catalysts by amalgamating the
metal catalyst or adsorbing on its surface but it does not deactivate
homogeneous systems. We chose as model reactions the hydro-
genation of styrene IX (Scheme 10) in the presence of the osmium
precatalyst 8a and the reduction of 2-cyclohexen-1-one I (Scheme
8) catalysed by ruthenium complex 5b, respectively: both experi-
ments were carried out at 80 ꢁC and 50 atm of H2 for 22 h. In the
case of the osmium catalyst, no effect of Hg(0) on the catalysis was
observed, so confirming the homogeneity of the reaction; on the
contrary, the suppression of catalysis by Hg(0) towards the ruthe-
nium complex was the evidence for a heterogeneous catalyst.
A 150-mL stainless steel reaction vessel was charged, under
a nitrogen purge, with 2.6 mmol of substrate, 0.0052 mmol of the
catalytic precursor and 5 mL of toluene. The reactor was then
pressurised at 50 atm of hydrogen, heated at 60e100 ꢁC for the due
time, then cooled to rt and the gas vented off. Conversions were
determined by GC analysis carried out on an Agilent 6850 Series gas
chromatograph, using an HP1 column (30 m ꢃ 0.32 mm ꢃ 0.25
mm).
For analytical purposes, the target products were recovered from
the reaction mixture by flash silica gel chromatography (n-hexane/
ether, 8/2). NMR measurements were used to test the stability of
the complexes in the catalytic reactions. The osmium complexes
[Os(1,3-ArNNNAr)(
ged at the end of the hydrogenation reactions, whereas only traces
h
6-p-cymene)L]BPh4 were recovered unchan-
of the precursor complexes [Ru(1,3-ArNNNAr)(
BPh4 were found in the case of ruthenium.
h
6-p-cymene)L]
3. Results and discussion
2.5.1. Homogeneity test
When transition-metal complexes are used as precatalysts in
hydrogenation processes, an important question is to establish the
nature of the active species. The true catalyst may be either
a homogeneous transition-metal complex or active metallic parti-
cles, present in solution as metal powder or metal nanoclusters,
3.1. Preparation of phosphite and isocyanide complexes
Reaction of dinuclear p-cymene complexes of ruthenium and
osmium [MCl(
in CH2Cl2 afforded mononuclear half-sandwich derivatives
MCl2(
6-p-cymene)L (1, 2) in excellent yield (Scheme 1).
tert-Butyl isocyanide [18] also reacts with dimeric compounds
[MCl( -Cl)(
6-p-cymene)]2 in CH2Cl2 to yield half-sandwich iso-
cyanide derivatives MCl2(
6-p-cymene)(CNR) (3, 4), which were
m-Cl)(h
6-p-cymene)]2 with an excess of phosphite (L)
h
Table 1
Crystal data and structure refinement.
m
h
h
Identification code
1b
10
isolated and characterised (Scheme 1).
Empirical formula
Formula weight
Temperature
Wavelength
Crystal system
Space group
C20H29Cl2O2PRu
504.37
C53H57BN4Ru
861.91
The reaction parallels that reported with common tertiary
phosphines [1,2,17b] and allows mononuclear complexes to be
prepared.
296(2) K
293(2) K
ꢀ
ꢀ
0.71073 A
0.71073 A
Monoclinic
Triclinic
P-1
p-Cymene complexes 1e4 were separated as red or orange
solids, stable in air and in solution of common organic solvents, in
which they behave as non-electrolytes [29]. Analytical and spec-
troscopic data (IR and NMR) support the proposed formulation for
the compounds.
P21/n
ꢀ
ꢀ
Unit cell dimensions
a ¼ 11.9383(5) A
a ¼ 11.1198(11) A
ꢀ
ꢀ
b ¼ 14.4755(7) A
b ¼ 14.9589(15) A
ꢀ
ꢀ
c ¼ 12.8598(5) A
c ¼ 15.4090(15) A
a
b
g
¼ 98.707(2)ꢁ
¼ 110.891(2)ꢁ
b
¼ 96.331(2)ꢁ
The 1H NMR spectra of phosphite complexes 1, 2 show the
characteristic signals of p-cymene hydrogen atoms and those of
phosphite substituents; a singlet appears between 138 and 69 ppm
in the 31P{1H} NMR spectra.
¼ 96.135(2)ꢁ
3
3
ꢀ
ꢀ
Volume
Z
2208.79(17) A
4
2330.9(4) A
2
Density (calculated)
Absorption coefficient
F(000)
Crystal size
Theta range for data
collection
1.517 Mg/m3
1.036 mmꢀ1
1032
1.228 Mg/m3
0.375 mmꢀ1
904
The IR spectra of isocyanide complexes 3, 4 show a strong band
at 2191e2185 cmꢀ1, attributable to nCN of the isocyanide ligand. 1H
and 13C{1H} NMR spectra confirm the presence of both isocyanide
and p-cymene ligands, showing their characteristic signals (see
Experimental).
0.29 ꢃ 0.20 ꢃ 0.14 mm 0.36 ꢃ 0.22 ꢃ 0.14 mm
2.13e26.43ꢁ
1.40e28.02ꢁ
Index ranges
ꢀ14 ꢄ h ꢄ 14;
ꢀ18 ꢄ k ꢄ 18;
ꢀ16 ꢄ l ꢄ 16
26325
ꢀ14 ꢄ h ꢄ 13;
ꢀ19 ꢄ k ꢄ 18;
ꢀ20 ꢄ l ꢄ 20
15310
To further support the formulation of phosphite complexes, we
determined the X-ray crystal structure of RuCl2(
(OEt)2] (1b), whose ORTEP is shown in Fig. 1. The complex adopts
typical ‘piano-stool’ geometry with the pseudo-tetrahedral
h
6-p-cymene)[PPh
Reflections collected
Independent reflections 4523 [R(int) ¼ 0.0530]
10652 [R(int) ¼ 0.0399]
Reflections observed
(>2
3597
5863
a
s)
arrangement of the p-cymene and other three ligands around the
metal center ruthenium. Bond angles subtended by the ligands
forming the legs and the ruthenium atom are all close to 90ꢁ
Data completeness
Absorption correction
0.996
Semi-empirical from
equivalents
0.943
Semi-empirical from
equivalents
Max. and min.
transmission
1.000 and 0.831
1.000 and 0.925
Refinement method
Full-matrix least-
squares on F2
4523/0/240
Full-matrix least-squares
on F2
10652/0/540
Data/restraints/
parameters
Cl
M
Goodness-of-fit on F2
Final R indices
1.064
1.051
Cl
exc. L
CH2Cl2, RT
M
R1 ¼ 0.0312
wR2 ¼ 0.0598
R1 ¼ 0.0458
wR2 ¼ 0.0632
R1 ¼ 0.0685 wR2 ¼ 0.1683
Cl
Cl
L
M
[I > 2
s(I)]
Cl
Cl
R indices (all data)
R1 ¼ 0.1293 wR2 ¼ 0.2103
1 - 4
ꢀꢀ3
ꢀꢀ3
Largest diff. peak and
hole
0.443, ꢀ0.457 eA
1.113, ꢀ1.445 eA
Scheme 1. M ¼ Ru (1, 3), Os (2, 4); L ¼ P(OEt)3 (a), PPh(OEt)2 (b) (1, 2); ButNC (3, 4).

G. Albertin et al. / Journal of Organometallic Chemistry 695 (2010) 2142e2152
2147
Table 2
(Table 2) and attest to the overall octahedral coordination of the
ꢀ
Selected bond lengths [A] and angles [deg] for 1b.
metal atom. The distance from the ruthenium atom to the centroid
ꢀ
of the planar p-cymene ring is 1.7102(2) A (Table 2), value within
RueP(1)
RueCl(1)
2.2807(7)
2.4171(7)
RueCl(2)
RueCTa
2.4038(7)
1.7102(2)
the range found in the literature for Ru(p-cymene) complexes
[9,30e34]. The ruthenium to carbon distances show some differ-
CTeRueP(1)
P(1)eRueCl(2)
P(1)eRueCl(1)
127.71(2)
87.89(2)
87.59(2)
CTeRueCl(2)
CTeRueCl(1)
Cl(2)eRueCl(1)
124.793(19)
127.287(19)
88.81(2)
ꢀ
ences, with an average RueC 2.218(3) A but in a wide range of 2.174
ꢀ
(3)e2.280(2) A. Longer values correspond to those trans to the
a
phosphorus atom and the shorter RueC bond corresponds to those
“over” the phosphorus atom, and consequently trans to chloro
ligands. The complex completes its coordination sphere with two
chlorine atoms and a diethoxyphenylphosphine ligand, and this
structure is usual in the literature, where p-cymene dihalo ruthe-
nium(II) complexes have been extensively studied [30e33], and do
not require further comment.
CT represents the centroid of the benzene ring for the p-cymene ligand.
species [MCl(
that, in the presence of triethylamine, the reaction proceeds to give
triazenide complexes MCl(
2-1,3-ArNNNAr)( 6-p-cymene)
(13e15), which were isolated in good yield and characterised
(Scheme 4).
m-Cl)(h
6-p-cymene)]2 with 1,3-triazene. Results show
h
h
Initial coordination of the 1,3-ArN]NN(H)Ar molecule to the
central metal is probably followed by deprotonation (NEt3), giving
the
3.2. Half-sandwich triazene complexes
h
2-coordination of the 1,3-ArNNNArꢀ ligand. The triazenide
Half-sandwich phosphite complexes MCl2(
react with 1,3-diaryltriazene 1,3-ArN]NN(H)Ar in the presence of
triethylamine to give triazenide complex cations [M(
2-1,3-ArNN-
NAr)(
6-p-cymene)L]þ (5e8), which were isolated as BPhꢀ4 salts
h
6-p-cymene)L (1, 2)
therefore splits the chloro bridge of the starting materials to give
the final monomeric derivatives 13e15. Treatment of these
complexes with phosphite or isocyanide in the presence of NaBPh4
h
led to the complexes [M(h h
2-1,3-ArNNNAr)( 6-p-cymene)L]BPh4
h
and characterised (Scheme 2).
(5e12) (Scheme 5) [5e12].
Related isocyanide complexes MCl2(h
6-p-cymene)(CNR) (3, 4)
The new half-sandwich triazenide complexes 5e15 were sepa-
rated as yellow or orange solids, stable in air and in solution of polar
organic solvents in which they behave as 1:1 electrolytes 5e12 or
non-electrolytes 13e15 [29]. Their formulation is supported by
analytical and spectroscopic data (IR and NMR spectra) and X-ray
also react with 1,3-ArN ¼ NN(H)Ar in the presence of NEt3 to give
triazenide-isocyanide derivatives [M(h h
2-1,3-ArNNNAr)( 6-p-cym-
ene)(CNR)]þ (9e12), which were separated as BPhꢀ4 salts in good
yield (Scheme 2). Crucial for successful synthesis is carrying out the
reaction in ethanol as solvent containing one equivalent of NaBPh4
and adding an excess of NEt3 later. Otherwise, the result is an
impure material, containing small amounts of triazenide complex.
crystal structure determination of [Ru(
6-p-cymene){CNC(CH3)3}]BPh4 (10), whose ORTEP is shown in
Fig. 2. The complex consists of a tetraphenylborate salt of a cation
complex with a ruthenium atom coordinated by a
6-p-cymene
h
2-1,3-p-tolyl-NNN-p-tolyl)
(h
The reaction of the the p-cymene complexes MCl2(
ene)L (1e4) (L ¼ phosphite or isocyanide) with 1,3-triazene prob-
h
6-p-cym-
h
ligand, a 1,3-di-p-tolyltriazenide, and a carbon atom from a tert-
butyl isocyanide group. This complex also adopts the typical ‘piano-
stool’ geometry. Bond angles subtended by the ligands forming the
legs and the ruthenium atom are all close to 90ꢁ (Table 3) and attest
to the overall octahedral coordination of the metal atom, except
chelate angle N(1)eRueN(2), with a value of 59.63(16)ꢁ due the
small-bite of the triazenide ligand. The distance from the ruthe-
nium atom to the centroid of the planar p-cymene ring is 1.7332
ably proceeds with initial
h
1-coordination of the triazene to the
metal center through substitution of one Clꢀ to give the interme-
diate [A] (Scheme 3).
Deprotonation of
h
1-triazene [35] in intermediate [A] by NEt3
allowed
h
2-coordination of the triazenide ArNNNArꢀ anion and
yielded the final complexes 5e12.
The preparation of triazenide complexes 5e12 with phosphites
or isocyanides also prompted us to study the reaction of dimeric
ꢀ
(4) A, value within the range found in the literature for Ru(p-
cymene) complexes [9,30e34]. The RueC distances range from
ꢀ
ꢀ
2.210(6) to 2.281(5) A [average RueC 2.236(6) A, and differences of
ꢀ
only 0.07 A]. It is noteworthy that the longest RueC bond involves
the iso-propyl substituted carbon atom and not the methyl-
substituted one, as observed for many cymene ruthenium
complexes [34]. The complex completes its coordination sphere
with a two nitrogen atoms from a bidentated 1,3-di-p-tolyl-
triazenide-k
(N,N00) and a carbon atom from a tert-butyl isocyanide
group. The small-bite of the triazene conditions the bond angles
around the metal, but only those affecting this ligand, in such a way
that the centroideRueCisocyanide angle has a value of 126.6 (5)ꢁ
(close to the theoretically expected 125.26ꢁ) and the
NeRueCisocyanide angles are close to the expected 90ꢁ. The chelate
angle of 59.6(2) is only slightly larger than those found for similar
Ru
Cl1
Cl2
P1
+
1,3-ArN=NN(H)Ar
NEt3, NaBPh4
M
M
L
L
–
BPh4
Cl
Ar
N
Cl
N
Ar
N
1 - 4
5 - 12
Scheme 2. M ¼ Ru (5, 6, 9, 10), Os (7, 8, 11, 12); Ar ¼ Ph (5, 7, 9, 11), p-tolyl (6, 8, 10, 12);
L ¼ P(OEt)3 (a), PPh(OEt)2 (b) (5e8), ButNC (9e12).
Fig. 1. The compound 1b drawn at 50% probability level.

2148
G. Albertin et al. / Journal of Organometallic Chemistry 695 (2010) 2142e2152
+
+
Ar
exc L
NaBPh4
H
M
M
1,3-ArN=NN(H)Ar
–Cl
N
Cl
L
–
BPh4
Ar
N
Ar
N
M
M
N
Ar
N
Ar
L
L
N
Cl
Cl
N
13 - 15
N
5 - 12
Cl
N
Ar
[ A ]
Scheme 5.
+
NEt3
–HCl
M
L
–
BPh4
proposed in Scheme 3, we reacted precursors MCl2(h
6-p-cymene)L
Ar
N
N
Ar
N
(L ¼ phosphites or isocyanides) with equimolar amounts of 1,3-
triazene in the absence of NEt3. Surprisingly, the reaction, in
ethanol containing NaBPh4, proceeds to give a mixture of tri-
5 - 12
Scheme 3. M ¼ Ru, Os; Ar ¼ Ph, p-tolyl; L ¼ phosphite or isocyanide.
azenide-[M(
amine complexes [MCl(ArNH2)(
h
2-1,3-ArNNNAr)(
h
6-p-cymene)L]BPh4 (5e12) and
h
6-p-cymene)L]BPh4 (16e21),
complexes by the Strähle group [9]. The NeN bond lengths in the
triazenide molecule are also only slightly longer than those
mentioned by the Strähle group, and are considered as a double
bond. Those values are also comparable to those obtained previ-
ously by our group [13], with the expected differences due the
different environment of the metal atom, and also to other triazene
complexes with ruthenium [36] or with other metals [37]. The tert-
which were separated by fractional crystallisation and charac-
terised (Scheme 6).
The reaction was also carried out in the absence of NaBPh4 but,
in this case, was very slow and gave only traces of triazenide
complexes. The presence of NaBPh4 is crucial for the progress of the
reaction, probably because it favors substitution of the chloride in
precursor MCl2(
1,3-triazene complexes of the type [MCl(
h
6-p-cymene)L, but does not allow preparation of
h
1-1,3-ArN]NN(H)Ar)(h6
-
butyl isocyanide group acts as a typical
C(41)eRu angle of 177.6(5)ꢁ and C(41)eN(4)eC(42) of 178.4(8)ꢁ,
close to the characteristic linearity of the poor d / p -back-
sedonor ligand, with N(4)e
p-cymene)L]BPh4 [A]. Instead, amine complexes 16e21 are formed
together with the known triazenide derivatives 5e12. This result is
not completely unexpected, taking into account both the plausible
p
ꢀ
bonding [38]. However, the C(41)eN(4) bond length, 1.161(8) A, is
path of the reaction between MCl2(h
6-p-cymene)L and 1,3-ArN]
quite long, but still consistent with a triple bond between both
ꢀ
atoms. The RueC bond length of 1.967(7) A is in the range of Ru-
NN(H)Ar (Scheme 3) and the properties of the free 1,3-triazene
molecule.
tert-butyl isocyanide complexes [39].
The 1H NMR spectra of complexes [M( 2-1,3-ArNNNAr)( 6-p-
h h
The triazenic hydrogen atom NH of complex [MCl(
h
1-1,3-ArN]
NN(H)Ar)(
h
6-p-cymene)L]þ [A], initially formed, is probably
cymene)L]BPh4 (5-8) show the characteristic signals of p-cymene
and phosphite ligands and, in the case of the p-tolyl triazenide,
there is also a singlet at 2.38e2.35 ppm of the methyl substituents.
However, support for the presence of the triazenide group comes
deprotonated either by the BPhꢀ4 anion, or by traces of water in the
solvent, giving triazenide derivatives 5e12. As a result, the acidity
of the solution increases (HBPh4, H3Oþ) during the reaction course,
and this may cause protonation of the aminic nitrogen atom of free
triazene ArN]NN(H)Ar (Scheme 7), leading to cleavage of the NeN
bond and formation of amine ArNH2 and aryldiazonium cation
ArNþ2 .
from the 15N{1H} NMR spectrum of the labeled complex [Os(
h
2-1,3-
which
Ph15NN15NPh)(
h
6-p-cymene){PPh(OEt)2}]BPh4
(7b*),
15 31
appears as a doublet at ꢀ188.9 ppm (J
¼ 5.2 Hz) due to
N
P
coupling with the phosphorus nucleus of the phosphite. The 31P
{1H} NMR spectra of all phosphite complexes are singlets, fitting the
proposed formulation.
In addition, amine ArNH2 can substitute one chloride in the
starting complex MCl2(
h
6-p-cymene)L to give the half-sandwich
The infrared spectra of isocyanide complexes [M(h
2-1,3-ArNN-
NAr)(h
6-p-cymene){CNC(CH3)3}]BPh4 (9e12) show a strong band
at 2191e2181 cmꢀ1 due to nCN of the ButNC ligand. 1H NMR data
confirm the presence of tert-butyl isocyanide showing not only the
signals of the p-cymene and triazenide ligands, but also a singlet at
1.30e1.28 ppm of the tert-butyl substituents. The 15N{1H} NMR
spectrum of [Os(h h
2-1,3-Ph15NN15NPh)( 6-p-cymene)(CNBut)]BPh4
(11*) appears as a singlet at e186.9 ppm, confirming the proposed
formulation for the complexes.
C41
Ru
N4
3.3. Preparation of amine derivatives
N2
N1
With the aim of synthesizing half-sandwich 1,3-triazene
complexes like complex [A] and thus supporting the reaction path
N3
Cl
M
Cl
1,3-ArN=NN(H)Ar
NEt3
M
Cl
Cl
Cl
M
Ar
N
N
Ar
N
13 - 15
Scheme 4. M ¼ Ru (13, 14), Os (15); Ar ¼ Ph (13), p-tolyl (14, 15).
Fig. 2. The cation 10 drawn at 30% probability level.

G. Albertin et al. / Journal of Organometallic Chemistry 695 (2010) 2142e2152
2149
Table 3
Selected bond lengths [A] and angles [ ] for 10.
Ar
ꢁ
ꢀ
+
N
N
H
+ H+
ArNH2 + Ar–N≡N:
RueC(41)
RueN(2)
C(11)eN(1)
N(3)eN(2)
C(41)eN(4)
1.967(7)
2.064(4)
1.396(6)
1.299(5)
1.161(8)
RueN(1)
RueCT
N(1)eN(3)
N(2)eC(21)
2.063(4)
1.7332(4)
1.327(6)
1.413(7)
Ar
N
+
ArNH2
CTeRueC(41)
126.65(15)
87.62(19)
87.9(2)
119.1(4)
118.5(4)
178.4(8)
CTeRueN(1)
CTeRueN(2)
N(1)eRueN(2)
N(2)eN(3)eN(1)
N(4)eC(41)eRu
135.91(13)
136.01(12)
59.63(16)
102.8(4)
M
M
L
L
C(41)eRueN(1)
C(41)eRueN(2)
N(3)eN(1)eC(11)
N(3)eN(2)eC(21)
C(41)eN(4)eC(42)
Cl
Cl
Cl
NH2Ar
16 - 21
177.6(5)
Scheme 7.
3.4. Catalytic activity
3.4.1. Hydrogenation with ruthenium complexes
amine derivatives 16e21. Support for this reaction path came from
the reaction with 1,3-Ph15N]N15N(H)Ph, which afforded both the
Ruthenium compounds are known to reduce a great variety of
substrates such as unfunctionalised or functionalised olefins,
ketones, aldehydes, esters, acids, imines, etc. [40e42]. In this
15N-labeled triazenide complexes [M( 2-1,3-Ph15NN15NPh)( 6-p-
h h
cymene)L]BPh4 (7b*, 11*) and the 15N-amine derivatives [MCl
(Ph15NH2)( 6-p-cymene)L]BPh4 (16b*, 18b*, 20*).
Amine complexes [MCl(ArNH2)(
6-p-cymene)L]BPh4 were also
prepared by reacting MCl2(
6-p-cymene)L with the appropriate
arylamine ArNH2 in ethanol containing NaBPh4.
Complexes [MCl(ArNH2)(
6-p-cymene)L]BPh4 (16e21) are
h
context, we tested some of our
h
6-p-cymene complexes, of the
h
types RuCl(h h h
2-1,3-ArNNNAr)( 6-p-cymene) and [Ru( 2-1,3-ArNN-
h
NAr)(h
6-p-cymene)L]BPh4 (L ¼ phosphite or isocyanide) in the
hydrogenation of a,b-unsaturated substrates such as 2-cyclohexen-
h
1-one I and cinnamaldehyde V, in order to study the activity of
these catalytic systems toward the reduction of the carbonecarbon
and carbon-oxygen double bond, respectively. A first set of exper-
iments was carried out on 2-cyclohexen-1-one I in toluene,
(Scheme 8) with a substrate-to-catalyst molar ratio of 500, at
60e80 ꢁC and 50 atm of hydrogen pressure for 22 h (Table 4).
yellow solids, stable in air and in solution of polar organic solvents,
in which they behave as 1:1 electrolytes [29]. Analytical and
spectroscopic data (IR, NMR) support the proposed formulation.
The IR spectra show two medium-intensity bands at
3318e3193 cmꢀ1 attributed to nNH of the amine group ArNH2. A
strong band at 2178e2174 cmꢀ1, due to nCN of the (CH3)3CNC ligand,
is also present in the isocyanide complexes 20 and 21.
The two
triazenide ligand, RuCl(
(14) and RuCl(
2-1,3-PhNNNPh)(
h
6-p-cymene catalytic precursors containing only the
2-1,3-p-tolyl-NNN-p-tolyl)( 6-p-cymene)
6-p-cymene) (13), respectively,
h
h
The 1H NMR spectra support the proposed formulation,
showing either the signals of the p-cymene and phosphite or
isocyanide ligand, and two slightly broad doublets between 5.75
and 4.42 ppm attributed to the two hydrogens of the amine
ligand. The stereogenic nature of the central metal causes split-
ting of the NH2 signals into the two observed multiplets. In the
h
h
showed quite low activity and selectivity. After 22 h at 80 ꢁC,
conversions were only about 30e35%: both cyclohexanone II and
cyclohexanol III were produced, but the saturated ketone II was the
main reaction product, obtained with about 70% selectivity (items 1
and 2, Table 4). When the triazenide-phosphite complexes 6b, 6a
and 5b were employed as catalysts for the hydrogenation of I at
80 ꢁC, complete substrate conversions were obtained and cyclo-
hexanol III, was the prevailing reaction product (run 3, 5 and 7,
Table 4). By performing the same reaction at 60 ꢁC revealed a lower
reaction rate, but the selectivity was now strongly shifted toward
cyclohexanone II (about 94%) (run 4, 6 and 8, Table 4).
spectra of labeled complexes [OsCl(Ph15NH2)( 6-p-cymene)L]
h
BPh4 (16b*, 18b*, 20*), the two broad doublets are replaced by
two doublets of doublets (of doublets, 16b*, 18b*), owing to the
15
1
15
coupling with the N nucleus (J
¼ 72.8 Hz), fitting the
H
N
proposed assignment. The proton-coupled 15N NMR spectra also
support the presence of the amine ligand showing a doublet of
15
1
H
triplets at ꢀ366.6 ppm (J
¼ 72.8 Hz) for 16b*, due to
N
Very surprisingly, catalytic precursor [Ru(
h
2-1,3-p-tolyl-NNN-p-
6-p-cymene)(PiPr3)]BPh4 (6c), containing the iso-propyl
coupling with both the NH2 hydrogen atoms and the 31P{1H}
nucleus of the phosphite, while only one triplet, at ꢀ387.6 ppm,
appears for isocyanide complex 20*. The 31P{1H} NMR spectra of
the phosphite complexes are sharp singlets, whereas the 13C{1H}
spectra of the isocyanide complexes 21 show a singlet of the
isocyanide carbon atom near 102 ppm, fitting the proposed
formulation for the amine derivatives.
tolyl)(
h
phosphine moiety, was practically inactive at 60 ꢁC; when the
hydrogenation experiment was carried out at 80 ꢁC, cyclohexenone
was totally converted into a mixture of the corresponding saturated
ketone II (88.1%) and alcohol III (11.9%) (runs 9 and 10, Table 4).
Lastly, isocyanide derivative [Ru(h h
2-1,3-p-tolyl-NNN-p-tolyl)( 6-p-
cymene)(tBuNC)}]BPh4 (10) was used as catalytic precursor: in this
case, at both 80 and 60 ꢁC, substrate conversion was complete, with
the formation of a mixture of II and III: depending on reaction
temperature, we observed complete inversion of selectivity (runs
11 and 12, Table 4).
1,3-ArN=NN(H)Ar
EtOH, NaBPh4
M
L
Cl
Cl
+
+
OH
O
O
OH
+
M
M
Ru cat.
H2
L
L
–
–
BPh4
BPh4
Ar
N
Cl
+
+
N
Ar
NH2Ar
N
5 - 12
16 - 21
III
I
II
IV
Scheme 6. M ¼ Ru (16, 17), Os (18e21); Ar ¼ Ph (16, 18, 20), p-tolyl (17, 19, 21); L ¼
P(OEt)3 (a), PPh(OEt)2 (b) (16e19), ButNC (20, 21).
Scheme 8.

2150
G. Albertin et al. / Journal of Organometallic Chemistry 695 (2010) 2142e2152
Table 4
Table 5
Hydrogenation of 2-cyclohexen-1-one I catalysed by ruthenium complexes.
Hydrogenation of cinnamaldehyde V catalysed by ruthenium complexes.
Run
Cat.
T (ꢁC)
Conv. (%)
II (%) selectivity
III (%) selectivity
Run Cat. T (ꢁC) t (h) Conv. (%) VI (%)
VII (%) VIII (%)
selectivity selectivity selectivity
1
2
3
4
5
6
7
8
14
13
6b
6b
6a
6a
5b
5b
6c
6c
10
10
80
80
80
60
80
60
80
60
80
60
80
60
30.2
35.6
100
87.2
100
91.7
100
75.8
100
2.7
72.2
72.7
27.5
94.1
23.9
93.2
37.9
94.5
88.1
2.7
27.8
27.3
72.5
5.9
76.1
6.8
62.1
5.5
11.9
e
1
2
3
4
5
6
7
14
13
6b
6a
5b
6c
10
100
100
100
100
100
100
100
24
24
17
17
17
17
17
50.2
56.0
95.9
83.9
90.8
33.7
56.6
58.0
27.7
29.4
25.0
35.9
20.6
18.1
19.6
52.6
48.6
53.1
9.1
25.5
22.4
19.7
22.0
21.9
55.0
e
100
79.4
9
Substrate ¼ 2.6 mmol; Cat. ¼ 0.0052 mmol; toluene ¼ 5 mL; p(H2) ¼ 50 atm.
10
11
12
100
100
39.2
63.9
60.8
36.1
good hydrogenating capability of this catalyst was confirmed by the
good formation of saturated alcohol VII, obtained with about 80%
selectivity. In general, these p-cymene-diaryltriazene ruthenium
complexes show fairly good activities, with TONs ranging from 150
to 500, comparable with other ruthenium(II)-p-cymene
compounds such as those described by Dyson and Chaplin [44].
These last complexes, however, work well also at 50 ꢁC, show
higher TOFs and are more selective for the reduction of carbonyl
groups in the presence of olefinic bonds. We can suppose that this
difference in activity and selectivity is probably due to the great
steric hindrance of the ligands bound to metal center of our cata-
lytic systems.
Substrate
p(H2) ¼ 50 atm.
¼
2.6 mmol; Cat.
¼
0.0052 mmol; toluene
¼
3
mL;
t
¼
22 h;
Interesting results were also obtained in the hydrogenation of
cinnamaldehyde V (Scheme 9). Hydrogenation of -unsaturated
a,b
aldehydes, particularly trans-cinnamaldehyde, is in fact an impor-
tant step in the production of some useful fine chemicals as inter-
mediates in the synthesis of pharmaceuticals, additives for food
flavours, and valuable building block for fragrances [43]. The cata-
lytic chemoselective hydrogenation of the carbonyl group is
a challenging task [40e42]: for example, bis-phosphine-ruthenium
(II)-(p-cymene) complexes have been used in the chemoselective
reduction of the carbonyl moiety of trans-cinnamaldehyde [44]
3.4.2. Hydrogenation with osmium complexes
Analogous complexes of osmium were also employed in the
hydrogenation process. Osmium derivatives are known to be active
in the hydrogenation of unfunctionalised olefins and a,b-unsatu-
and, more recently, the dinuclear complex [Ru(PhBP3)(m-Cl)]2,
containing the tripodal phosphonoborate ligand [PhB(CH2PPh2)3]-,
turned out to be very active and selective in the hydrogenation of
cinnamaldehyde to the corresponding unsaturated alcohol VIII
[45]. Although cinnamyl alcohol VIII is highly desirable, reduction
of the carbonecarbon double bond is generally thermodynamically
favoured over carbonyl reduction and 3-phenylpropanal VI and/or
3-phenylpropanol VII therefore formed.
rated compounds [25,46e52]. For example, styrene had been effi-
ciently hydrogenated to ethylbenzene by using tetranuclear
osmium clusters at ambient pressure and 140 ꢁC: these complexes
are effective homogeneous catalysts even if they probably undergo
fragmentation to produce lower nuclearity species responsible for
the activity [25]. Also mononuclear osmium complexes modified
with phosphino ligands were employed in the hydrogenation of
styrene under ambient hydrogen pressure at 60 ꢁC [25,46e48]. In
this context, we first carried out some hydrogenation experiments
on styrene IX at 80 ꢁC and 50 atm of H2 for 22 h, by using
a substrate-to-catalyst molar ratio of 500/1 (Scheme 10).
By analogy with the experiments carried out on 2-cyclohexen-
1-one I, first, we evaluated the activity of the two catalytic
precursors not containing any phosphorus ligand, 14 and 13,
respectively: as was observed in the hydrogenation of I, their
activity was quite low, giving only about 50% substrate conversion
after 24 h at 100 ꢁC and 50 atm of H2 pressure. These catalysts
showed good capability to hydrogenate both C]C and C]O double
bonds, affording a mixture of the saturated aldehyde VI, corre-
sponding alcohol VII, and cinnamyl alcohol VIII: in both cases, VI
was the main reaction product (runs 1 and 2, Table 5). Ruth-
eniumephosphite complexes 6b, 6a and 6c, after 17 h at 100 ꢁC,
gave high substrate conversions: in all cases 3-phenylpropanol VII
was the main reaction product (runs 3e5, Table 5). Ruthenium
complex 6c, modified with iso-propylphosphine, was much less
active, furnishing only about 34% of substrate conversion, and
cinnamyl alcohol VIII, the main reaction product, was obtained
with 55% selectivity (run 6, Table 5). Lastly, compound 10, con-
taining the isocyanide ligand, was employed as catalytic precursor:
its activity, like that observed in 2-cyclohexen-1-one hydrogena-
tion, was very high, affording 100% of substrate conversion. The
All the catalytic precursors employed were very active, affording
ethylbenzene X in very good yields (80e100%) (see Table 6). We
then carried out hydrogenation experiments on 2-cyclohexen-1-
one I. The hydrogenation of 2-cyclohexen-1-one was efficiently
carried out by Sanchez-Delgado et al. in the presence of the
homogeneous catalyst OsH(Br)(CO)(PPh3)3: under H2 atmospheric
pressure at 100 ꢁC, the
a,b-unsaturated substrate was reduced to
cyclohexanone with 100% yield; by increasing the reaction
temperature to 150 ꢁC and H2 pressure to 5 atm, conversion was
complete but, in this case, a mixture of cyclohexanone (69%) and
cyclohexanol (31%) was obtained [49]. More recently, 2-cyclo-
hexen-1-one has been hydrogenated in the presence of the cationic
complex [OsH(CO)(NCMe)2(PPh3)2]BF4 at 100 ꢁC and 4 atm of H2:
cyclohexanone was selectively produced by allowing the reaction
O
OH
O
OH
Ru cat.
H2
VI
V
VII
VIII
Scheme 9.

G. Albertin et al. / Journal of Organometallic Chemistry 695 (2010) 2142e2152
2151
Table 7
Os cat.
H2
Hydrogenation of 2-cyclohexen-1-one I catalysed by osmium complexes.
Run
Cat.
T (ꢁC)
Conv. (%)
II (%) selectivity
III (%) selectivity
1
2
3
4
5
6
7
8
9
8a
8a
8b
8b
7b
7b
15
15
20
20
80
100
80
100
80
100
80
100
80
19.2
100
17.5
100
20.9
100
10.1
100
88.5
57.8
85.1
61.3
80.0
58.4
100
81.3
84.2
e
11.5
42.2
14.9
38.7
20.0
41.6
X
IX
Scheme 10.
to occur in 2-methoxyethanol, as well as in toluene solution [50].
We carried out our hydrogenation experiments on 2-cyclohexen-1-
one at 80 ꢁC and 50 atm of H2 for 22 h, by using a substrate/catalyst
molar ratio of 500/1.
e
28.7
15.8
100
76.6
100
10
100
Cationic complexes [Os(
ene){P(OEt)3}]BPh4 (8a), [Os(
(OEt)2}]BPh4 (7b) and [Os(
2-1,3-p-tolyl-NNN-p-tolyl)(
h
2-1,3-p-tolyl-NNN-p-tolyl)(
2-1,3-PhNNNPh)( 6-p-cymene){PPh
6-p-cym-
h
6-p-cym-
Substrate ¼ 2.6 mmol; Cat. ¼ 0.0052 mmol; toluene ¼ 5 mL; p(H2) ¼ 50 atm;
t ¼ 22 h.
h
h
h
h
ene){PPh(OEt)2}]BPh4 (8b) gave low substrate conversions, afford-
ing a mixture of cyclohexanone II and cyclohexanol III: ketone II,
the main reaction product, was obtained with 80e85% selectivity
4. Conclusions
(see Table 7). The neutral osmium derivative OsCl(
h
2-1,3-p-tolyl-
In this paper we report the synthesis of half-sandwich
complexes of ruthenium and osmium containing 1,3-triazenide as
NNN-p-tolyl)(
h
6-p-cymene) (15), not containing any phosphorus
a supporting ligand of the types [M(
ene)L]BPh4 (L ¼ phosphite or isocyanide) and MCl(
NAr)(
6-p-cymene). A new reaction of the p-cymene complexes
MCl2(
6-p-cymene)L, which yielded the amine derivative [MCl
(ArNH2)(
6-p-cymene)L]BPh4 when treated with equimolar
h
2-1,3-ArNNNAr)(
h
6-p-cym-
ligand, was even less active (10% conversion) and afforded cyclo-
hexanone II as the only reaction product. A better result was
obtained by performing the reaction in the presence of the iso-
h
2-1,3-ArNN-
h
h
cyanide derivative [OsCl(PhNH2)(h
6-p-cymene)(ButNC)]BPh4 (20)
h
which, after 22 h at 80 ꢁC, gave a substrate conversion of about 77%.
Again, a mixture of II and III was produced and cyclohexanone II
was the prevailing reaction product (84.2% selectivity). In order to
increase the catalytic activity of the above osmium complexes, the
reaction temperature was taken to 100 ꢁC. Very interestingly, as
shown in Table 7, the temperature not only brought substrate
conversion to 100%, but also enhanced the capacity for hydroge-
nation of the C]O double bond. All the cationic osmium complexes
containing a phosphite ligand did afford alcohol III in about 40%
yield (runs 2, 4 and 6, Table 7) and the most active isocyanide
complex 20 produced cyclohexanol at a yield as high as 100% (run
10, Table 7).
amounts of diaryltriazene 1,3-ArN]NN(H)Ar, is also reported.
Characterisation of new compounds by spectroscopic (1H, 31P, 13C,
15N NMR) and crystallographic (X-ray) data is discussed. Triazenide
complexes [M(h h
2-1,3-ArNNNAr)( 6-p-cymene)L]BPh4 are active
catalysts in the hydrogenation of both substrates 2-cyclohexen-1-
one and cinnamaldehyde, and isocyanide complexes show better
hydrogenation capability than phosphite ones.
Acknowledgment
The financial support of MIUR (Rome)-PRIN 2008 is gratefully
acknowledged. We thank Mrs. Daniela Baldan for her technical
assistance.
When these osmium-based catalytic precursors were used to
hydrogenate cinnamaldehyde at 100 ꢁC and 50 atm of H2 for 22 h,
very disappointing results were obtained: in all cases, 3-phenyl-
propanal VI, the only reaction product, was obtained in practically
negligible amounts (2e3%). This result was quite surprising, as
cinnamaldehyde had been efficiently hydrogenated by Sanchez-
Delgado et al. in the presence of osmium complexes modified with
PPh3 at 100 ꢁC and 30 atm of H2. Very interestingly, complex
OsCl2(PPh3)3 produced an almost equimolar mixture of the satu-
rated aldehyde and the saturated alcohol, whereas complexes
OsH4(PPh3)3 and OsHCl(CO)(PPh3)3 were more selective for the
formation of cinnamyl alcohol [47]. Korean authors have also
reported the hydrogenation of cinnamaldehyde with hydrido-
carbonyl osmium complexes containing diphosphine ligands, and
observed that the C]O bond was more easily reduced than the C]
C bond [51]. In our case, the lack of catalytic activity was probably
due to the great steric hindrance of our catalytic precursors,
hindering the coordination of the substrate to the osmium center.
References
[1] (a) M.A. Bennett, Coord. Chem. Rev. 166 (1997) 225e254;
(b) M.A. Bennett, in: E.W. Abel, F.G.A. Stone, G. Wilkinson (Eds.), Comprehensive
organometallic chemistry II, vol. 7, Elsevier, Oxford, 1995, pp. 549e602;
(c) H. Le Bozec, D. Touchard, P.H. Dixneuf, Adv. Organomet. Chem. 29 (1989)
163e247;
(d) T. Naota, H. Takaya, S.-I. Murahashi, Chem. Rev. 98 (1998) 2599e2660.
[2] (a) F. Marchetti, C. Pettinari, R. Pettinari, A. Cerquetella, C. Di Nicola,
A. Macchioni, D. Zuccaccia, M. Monari, F. Piccinelli, Inorg. Chem. 47 (2008)
11593e11603;
(b) A. Prades, M. Viciano, M. Sanau, E. Peris, Organometallics 27 (2008)
4254e4259;
(c) R. Castarlenas, M.A. Esteruelas, E. Oñate, Organometallics 27 (2008)
3240e3247;
(d) A.B. Chaplin, C. Fellay, G. Laurenczy, P.J. Dyson, Organometallics 26 (2007)
586e593;
(e) J. Wolf, K. Thommes, O. Briel, R. Scopelliti, K. Severin, Organometallics 27
(2008) 4464e4474;
(f) J. Vergnaud, M. Grellier, G. Bouhadir, L. Vendier, S. Sabo-Etienne,
D. Bourissou, Organometallics 27 (2008) 1140e1146.
[3] (a) E. Bustelo, P.H. Dixneuf, Adv. Synth. Catal. 347 (2005) 393e397;
(b) R. Castarlenas, P.H. Dixneuf, Angew. Chem. Int. Ed. 42 (2003) 4524e4527;
(c) E.J. Farrington, J.M. Brown, C.F.J. Barnard, E. Rowsell, Angew. Chem. Int. Ed.
41 (2002) 169e171;
Table 6
Hydrogenation of styrene IX catalysed by osmium complexes.
Run
Cat.
T (ꢁC)
X yield (%)
1
2
3
4
5
8b
8a
7b
15
20
80
100
80
100
80
84.3
95.0
80.5
100
(d) J. Hannedouche, G.J. Clarkson, M. Wills, J. Am. Chem. Soc. 126 (2004)
986e987;
(e) Y.-G. Zhou, W. Tang, W.-B. Wangm, L. Li, X. Zhang, J. Am. Chem. Soc. 124
(2002) 4952e4953;
(f) R. Akiyama, S. Kobayashi, Angew. Chem. Int. Ed. 41 (2002) 2602e2604;
(g) R. Noyori, S. Hashiguchi, Acc. Chem. Res. 30 (1997) 97e102;
(h) L. Qiu, Y. Kwong, J. Wu, W.H. Lam, S. Chan, W.-Y. Yu, Y.-M. Li, R. Guo,
Z. Zhou, A.S.C. Chan, J. Am. Chem. Soc. 128 (2006) 5955e5965.
100
Substrate ¼ 2.6 mmol; Cat. ¼ 0.0052 mmol.
Toluene ¼ 5 mL; p(H2) ¼ 50 atm; t ¼ 22 h.

2152
G. Albertin et al. / Journal of Organometallic Chemistry 695 (2010) 2142e2152
[4] (a) J. Canivet, L. Karmazin-Brelot, G. Süss-Fink, J. Organomet. Chem. 690 (2005)
3202e3211;
[16] G. Balacco, J. Chem. Inf. Comput. Sci. 34 (1994) 1235e1241.http://www.inmr.
net/.
(b) C.Z. Flores-Lopez, L.Z. Flores-Lopez, G. Aguirre, L.H. Hellberg, M. Parra-
Hake, R. Somanathan, J. Mol. Cat. A: Chem. 215 (2004) 73e79;
(c) D. Sterk, M.S. Stephan, B. Mohar, Tetrahedron: Asymmetry 13 (2002)
2605e2608;
(d) B. De Clercq, F. Verpoort, J. Mol. Cat. A 180 (2002) 67e76;
(e) S. Ogo, T. Abura, Y. Watanabe, Organometallics 21 (2002) 2964e2969;
(f) A. Kathó, D. Carmona, F. Viguri, C.D. Remecha, J. Kovacs, F. Joó, L.A. Oro,
J. Organomet. Chem. 593e594 (2000) 299e306;
[17] (a) M.A. Bennett, T.-N. Huang, T.W. Matheson, A.K. Smith, Inorg. Synth. 21
(1982) 74e75;
(b) J.A. Cabeza, P.M. Maitlis, J. Chem. Soc., Dalton Trans. (1985) 573e578.
[18] The tert-butyl isocyanide complex of ruthenium was previously reported:
E. Hodson, S.J. Simpson Polyhedron 23 (2004) 2695e2707.
[19] SMART Version 5.054. Instrument Control, Data Collection Software. Bruker
Analytical X-ray Systems Inc., Madison, Wisconsin, USA, 1997.
[20] SAINT Version 6.01. Data Integration Software Package. Bruker Analytical X-
ray Systems Inc., Madison, Wisconsin, USA, 1997.
[21] APEX2 v. 2.0-1. Bruker AXS Inc., Madison, Wisconsin, USA, 2005.
[22] G.M. Sheldrick, SADABS. A Computer Program for Absorption Corrections.
University of Göttingen, Germany, 1996.
(g) A. Fujii, S. Hashiguchi, N. Uematsu, T. Ikariya, R. Noyori, J. Am. Chem. Soc.
118 (1996) 2521e2522.
[5] (a) S. Ogo, K. Uehara, T. Abura, Y. Watanabe, S. Fukuzumi, Organometallics 23
(2004) 3047e3052;
(b) A.W. Stumpf, E. Saive, A. Demonceau, A.F. Noels, J. Chem. Soc., Chem.
Commun. (1995) 1127;
(c) R. Castarlenas, P.H. Dixneuf, Angew. Chem. Int. Ed. 42 (2003) 4524e4527;
(d) M. Bassetti, F. Centola, D. Sémeril, C. Bruneau, P.H. Dixneuf, Organome-
tallics 22 (2003) 4459e4466;
[23] P. McArdle, J. Appl. Cryst. 28 (1995) 65e66.
[24] G.M. Sheldrick, Acta Cryst. A64 (2008) 112e122.
[25] R.A. Sánchez-Delgado, A. Andriollo, J. Puga, G. Martin, Inorg. Chem. 26 (1987)
1867e1870.
[26] J.P. Collman, L.S. Hegedus, J.R. Norton, R.G. Finke, Principles, Applications of
Organotransition Metal Chemistry. University Science Books, Mill Valley, CA,
1987.
[27] J.A. Widegren, M.A. Bennett, R.G. Finke, J. Am. Chem. Soc. 125 (2003)
10301e10310.
[28] P. Dyson, Dalton Trans. (2003) 2964e2974.
(e) R. Akiyama, S. Kobayashi, Angew. Chem. Int. Ed. 41 (2002) 2602e2604;
(f) A. Fürstner, M. Liebl, C.W. Lehmann, M. Picquet, R. Kunz, C. Bruneau,
D. Touchard, P.H. Dixneuf, Chem. Eur. J. 6 (2000) 1847e1857.
[6] (a) M.K. Tse, H. Jiao, G. Anilkumar, B. Bitterlich, F.G.A. Gelalcha, M. Beller,
J. Organomet. Chem. 691 (2006) 4419e4433;
(b) M.K. Tse, C. Döbler, S. Bhor, M. Klawonn, W. Mägerlein, H. Hugl, M. Beller,
Angew. Chem. Int. Ed. 43 (2004) 5255e5260.
[7] (a) T. Bugarcic, A. Habtemariam, J. Stepankova, P. Heringova, J. Kasparkova, R.
J. Deeth, R.D.L. Johnstone, A. Prescimone, A. Parkin, S. Parsons, V. Brabec, P.
J. Sadler, Inorg. Chem. 47 (2008) 11470e11486;
[29] W.J. Geary, Coord. Chem. Rev. 7 (1971) 81e122.
[30] (a) T. Sumiyoshi, T.B. Gunnoe, J.L. Petersen, P.D. Boyle, Inorg. Chim. Acta 361
(2008) 3254e3262;
(b) V. Cadierno, J. Díez, J. García-Álvarez, J. Gimeno, J. Rubio-García, Dalton
Trans. (2008) 5737e5748.
(b) R. Schuecker, R.O. John, M.A. Jakupec, V.B. Arion, B.K. Keppler, Organo-
metallics 27 (2008) 6587e6595;
(c) W.H. Ang, P.J. Dyson, Eur. J. Inorg. Chem. (2006) 4003e4018;
(d) C.A. Vock, C. Scolaro, A.D. Phillips, R. Scopelliti, G. Sava, P.J. Dyson, J. Med.
Chem. 49 (2006) 5552e5561.
[31] (a) D.K. Gupta, A.N. Sahay, D.S. Pandey, N.K. Jha, P. Sharma, G. Espinosa,
A. Cabrera, M.C. Puerta, P. Valerga, J. Organomet. Chem. 568 (1998) 13e20;
(b) A.R. Cowley, J.R. Dilworth, A.K. Nairn, A.J. Robbie, Dalton Trans. (2005)
680e693.
[32] R. Venkateswaran, J.T. Mague, M.S. Balakrishna, Inorg. Chem. 46 (2007)
809e817.
[33] E. Hodson, S.J. Simpson, Polyhedron 23 (2004) 2695e2707.
[34] J. Cubrilo, I. Hartenbach, F. Lissner, T. Schleid, M. Niemeyer, R.F. Winter,
J. Organomet. Chem. 692 (2007) 1496e1504.
[35] (a) J.W. Sutherland, J. Phys. Chem. 83 (1979) 789e795;
(b) E. Sawicki, T.R. Hauser, T.W. Stanley, Anal. Chem. 31 (1959) 2063e2065;
(c) L.D. Hansen, B.D. West, E.J. Baca, C.L. Black, J. Am. Chem. Soc. 90 (1968)
6588e6592.
[8] (a) F. Marchetti, C. Pettinari, R. Pettinari, A. Cerquetella, A. Cingolani, E.J. Chan,
K. Kozawa, B.W. Shelton, A.H. White, R. Wanke, M.L. Kuznetsov, L.M.D.R.
S. Martins, A.J.L. Pombeiro, Inorg. Chem. 46 (2007) 8245e8257;
(b) C.J. Jones, J.A. McCleverty, A.S. Rothin, J. Chem. Soc., Dalton Trans. (1986)
109e111;
(c) S. Bhambri, D.A. Tocher, J. Organomet. Chem. 507 (1996) 291e293;
(d) S. Bhambri, A. Bishop, N. Kaltsoyannis, D.A. Tocher, J. Chem. Soc., Dalton
Trans. (1998) 3379e3390;
(e) S. Bhambri, D.A. Tocher, J. Chem. Soc., Dalton Trans. (1997) 3367e3372.
[9] C.F. Barboza da Silva, S. Schwarz, M.G. Mestres, S.T. López, J. Strähle, Z. Anorg.
Allg. Chem. 630 (2004) 1919e1923.
[10] (a) L.D. Brown, J.A. Ibers, J. Am. Chem. Soc. 98 (1976) 1957e1958;
(b) A. Immirzi, W. Porzio, G. Bombieri, L. Toniolo, J. Chem. Soc., Dalton Trans.
(1980) 1098e1100.
[36] (a) A.A. Danopoulos, R.S. Hay-Motherwell, G. Wilkinson, S.M. Cafferkey, T.K.
N. Sweet, M.B. Hursthouse, J. Chem. Soc., Dalton Trans. (1997) 3177e3184;
(b) S.F. Colson, S.D. Robinson, D.A. Tocher, J. Chem. Soc., Dalton Trans. (1990)
629e633.
[37] A.G.M. Barrett, M.R. Crimmin, M.S. Hill, P.B. Hitchcock, G. Kociock-Köhn,
P.A. Procopiou, Inorg. Chem. 47 (2008) 7366e7376 and references
therein.
[11] (a) K.R. Laing, S.D. Robinson, M.F. Uttley, J. Chem. Soc., Dalton Trans. (1974)
1205e1214;
[38] (a) R. Garcia, A. Paulo, A. Domingos, I. Santos, H.-J. Pietzsch, Synth. React.
Inorg. Nano-Met. Chem. 35 (2005) 35e42;
(b) H. Spies, M. Glaser, H.-J. Pietzsch, F.E. Hahn, T. Lügger, Inorg. Chim. Acta
240 (1995) 465e478.
[39] (a) N.A. Foley, M. Lail, J.P. Lee, T.B. Gunnoe, T.R. Cundari, J.L. Petersen, J. Am.
Chem. Soc. 129 (2007) 6765e6781;
(b) R. Rossi, A. Duatti, L. Magon, L. Toniolo, Inorg. Chim. Acta 48 (1981)
243e246;
(c) R. Rossi, A. Duatti, L. Magon, W. Casellato, R. Graziani, L. Toniolo, J. Chem.
Soc., Dalton Trans. (1982) 1949e1952;
(d) A. Marchi, R. Rossi, A. Duatti, L. Magon, V. Bertolasi, V. Ferretti, G. Gilli,
Inorg. Chem. 24 (1985) 4744e4748;
(e) G.L. Hillhouse, B.L. Haymore, Inorg. Chem. 26 (1987) 1876e1885;
(f) S.F. Colson, S.D. Robinson, Polyhedron 7 (1988) 417e418;
(g) S.F. Colson, S.D. Robinson, Inorg. Chim. Acta 149 (1988) 13e14;
(h) C. Carriedo, N.G. Connelly, R. Hettrich, A.G. Orpen, J.M. White, J. Chem. Soc.,
Dalton Trans. (1989) 745e748;
(b) S. Takemoto, S. Oshio, T. Shiromoto, H. Matsuzaka, Organometallics 24
(2005) 801e804;
(c) A.K. Brisdon, K.R. Flower, R.G. Pritchard, Inorg. Chem. 46 (2007)
7189e7192.
[40] R. Noyori, T. Ohkuma, Angew. Chem. Int. Ed. 40 (2001) 40e73 and references
therein.
(i) M. Menon, A. Pramanik, S. Chattopadhyay, N. Bag, A. Chakravorty, Inorg.
Chem. 34 (1995) 1361e1367;
(j) S. Westhusin, P. Gantzel, P.J. Walsh, Inorg. Chem. 37 (1998) 5956e5959.
[12] (a) N.G. Connelly, G. Garcia, J. Chem. Soc., Dalton Trans. (1987) 2737e2749;
(b) H.G. Ang, L.L. Koh, G.Y. Yang, J. Chem. Soc., Dalton Trans. (1996)
1573e1581;
[41] M. Kitamura, R. Noyori, in: S.-I. Murahashi (Ed.), Hydrogenation, Transfer
Hydrogenation in Ruthenium in Organic Synthesis, Wiley-VCH, Weinheim, 2004.
[42] J.G. de Vries, C.J. Elsevier (Eds.), Handbook of Homogeneous Hydrogenation,
vol. 1, Wiley-VCH, Weinheim, 2007.
[43] K. Nuithitikul, M. Winterbottom, Chem. Eng. Sci. 59 (2004) 5439e5447.
[44] A.B. Chaplin, P.J. Dyson, Organometallics 26 (2007) 4357e4360 and references
therein.
[45] S. Jiménez, J.A. López, M.A. Ciriano, C. Tejel, A. Martínez, R.A. Sánchez-Delgado,
Organometallics 28 (2009) 3193e3202 and references therein.
[46] R.A. Sánchez-Delgado, M. Rosales, M.A. Esteruelas, L.A. Oro, J. Mol, Catal.
A: Chem. 96 (1995) 231e243 and references therein.
[47] R.A. Sánchez-Delgado, M. Medina, F. López-Linares, A. Fuentes, J. Mol. Catal.
A: Chem. 116 (1997) 167e177.
[48] M. Aracama, M.A. Esteruelas, F.J. Lahoz, J.A. Lopez, U. Meyer, L.A. Oro,
H. Werner, Inorg. Chem. 30 (1991) 288e293.
[49] R.A. Sánchez-Delgado, A. Andriollo, E. Gonzalez, N. Valencia, V. Leon, J. Espidel,
J. Chem. Soc. Dalton Trans. (1985) 1859e1863.
[50] M. Rosales, A. González, M. Mora, N. Nader, J. Navarro, L. Sanchez, H. Soscún,
Transit. Metal Chem. 29 (2004) 205e211.
(c) H.G. Ang, L.L. Koh, S.G. Ang, S.Y. Ng, G.Y. Yang, J. Chem. Soc., Dalton Trans.
(1996) 4083e4088.(d) N.G. Connelly, T. Einig, G. Garcia Herbosa, P.M. Hopkins,
C. Mealli, A.G. Orpen, G.M. Rosair, F. Viguri, J. Chem. Soc., Dalton Trans. (1994)
2025e2039;
(e) J. Ruiz, J.F.J. López, V. Rodriguez, J. Perez, M.C. Ramirez de Arellano, G. Lopez, J.
Chem. Soc., Dalton Trans. (2001) 2683e2689;
(f) N.G. Connelly, O.D. Hayward, P. Klangsinsirikul, A.G. Orpen, J. Chem. Soc.,
Dalton Trans. (2002) 305e306;
(g) C. Tejel, M.A. Ciriano, G. Rios-Moreno, I.T. Dobrinovitch, F.J. Lahoz, L.A. Oro,
M. Porra-Hake, Inorg. Chem. 43 (2004) 4719e4726;
(h) N. Nimitsiriwat, V.C. Gibson, E.L. Marshall, P. Takolpuckdee, A.K. Tomov, A.J.
P. White, D.J. Williams, M.R.J. Elsegood, S.H. Dale, Inorg. Chem. 46 (2007)
9988e9997.
[13] G. Albertin, S. Antoniutti, M. Bedin, J. Castro, S. García-Fontán, Inorg. Chem. 45
(2006) 3816e3825.
[51] M.-K. Jung, S. Huh, W.-Y. Lee, M.-J. Jin, Bull. Korean Chem. Soc. 18 (1997)
806e810.
[14] R. Rabinowitz, J. Pellon, J. Org. Chem. 26 (1961) 4623e4626.
[15] W.W. Hartman, J.B. Dickey, Org. Synth. 2 (1943) 163e165.
[52] W. Baratta, M. Ballico, G. Chelucci, K. Siega, P. Rigo, Angew. Chem. Int. Ed. 47
(2008) 4362e4365.