Preparation of benzophenone imine complexes of transition metals

Article abstract of DOI:10.1016/j.ica.2006.12.001

Benzophenone imine [M (η¹ -NH {double bond, long} CPh₂) (CO)_n P_{5 - n}] BPh₄ [M = Mn, Re; n = 2, 3; P = P(OEt)₃, PPh(OEt)₂, PPh₂OEt, PPh₃] complexes were prepared by allowing triflate M (κ¹ -OTf) (CO)_n P_{5 - n} compounds to react with an excess of the imine. Hydride-imine [MH (η¹ -NH {double bond, long} CPh₂) P₄] BPh₄ (M = Ru, Os), triflate-imine [Os (κ¹ -OTf) (η¹ -NH {double bond, long} CPh₂) P₄] BPh₄ and bis(imine) [Ru (η¹ -NH {double bond, long} CPh₂)₂ P₄] (BPh₄)₂ [P = P(OEt)₃] derivatives were also prepared. The complexes were characterized spectroscopically (IR, ¹H, ³¹P, ¹³C NMR) and a geometry in solution was also established. Hydride-benzophenone imine [IrHCl (η¹ -NH {double bond, long} CPh₂) L (PPh₃)₂] BPh₄and [IrHCl (η¹ -NH {double bond, long} CPh₂) L (AsPh₃)₂] BPh₄ [L = P(OEt)₃ and PPh(OEt)₂] complexes were prepared by reacting hydride IrHCl₂ L (PPh₃)₂ and IrHCl₂ L (AsPh₃)₂ precursors with an excess of imine. Dihydride IrH₂ (η¹ -NH {double bond, long} CPh₂) (PPh₃)₃ complex was also obtained and a geometry in solution was proposed.

Full text of DOI:10.1016/j.ica.2006.12.001

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Inorganica Chimica Acta 361 (2008) 1744–1753
www.elsevier.com/locate/ica
Preparation of benzophenone imine complexes of transition metals
*
Gabriele Albertin , Stefano Antoniutti, Alberto Magaton
`
Dipartimento di Chimica, Universita Ca’ Foscari di Venezia, Dorsoduro, 2137, 30123 Venezia, Italy
Received 22 September 2006; accepted 1 December 2006
Available online 6 December 2006
Dedicated to Piero Zanello.
Abstract
Benzophenone imine ½Mðg1-NH@CPh2ÞðCOÞnP5ꢀnꢁBPh4 [M = Mn, Re; n = 2, 3; P = P(OEt)3, PPh(OEt)2, PPh2OEt, PPh3] com-
plexes were prepared by allowing triflate Mðj1-OTfÞðCOÞnP5ꢀn compounds to react with an excess of the imine. Hydride-imine
½MHðg1-NH@CPh2ÞP4ꢁBPh4 (M = Ru, Os), triflate-imine ½Osðj1-OTfÞðg1-NH@CPh2ÞP4ꢁBPh4 and bis(imine) ½Ruðg1-NH@CPh2Þ2P4ꢁ-
ðBPh4Þ [P = P(OEt)3] derivatives were also prepared. The complexes were characterized spectroscopically (IR, 1H, 31P, 13C NMR)
2
and a geometry in solution was also established. Hydride-benzophenone imine ½IrHClðg1-NH@CPh2ÞLðPPh3Þ2ꢁBPh4 and ½IrHCl-
ðg1-NH@CPh2ÞLðAsPh3Þ2ꢁBPh4 [L = P(OEt)3 and PPh(OEt)2] complexes were prepared by reacting hydride IrHCl2LðPPh3Þ2 and
IrHCl2LðAsPh3Þ2 precursors with an excess of imine. Dihydride IrH2ðg1-NH@CPh2ÞðPPh3Þ3 complex was also obtained and a geometry
in solution was proposed.
Ó 2006 Elsevier B.V. All rights reserved.
Keywords: Benzophenone imine complexes; Manganese and rhenium; Ruthenium and osmium; Iridium; Phosphite ligands; Synthesis
1. Introduction
studies highlighted interesting properties. We have now
extended these studies to a species comparable to the dia-
zene group, such as imines (Chart 1), with the aim of deter-
mining whether synthesis of imine complexes can be
achieved for these metals and, if possible, of comparing
results with related diazene derivatives.
The results of these studies, which allow the synthesis of
mono- and bis(benzophenone imine) complexes of several
transition metals, are reported here.
Despite the large number of known transition metal
complexes containing multidentate imine ligands [1], the
monodentate nitrogen-bond imine derivatives are rather
rare [2]. This is somewhat surprising, and may be partly
due to the weak Lewis basicity of the imine nitrogen atom
[1,2]. However, coordination of an imine on a metal frag-
ment would be an important step in its activation toward
nucleophilic attack or its hydrogenation reaction to give
the amine. Stable complexes can provide models for key
intermediate and reaction steps.
2. Experimental
We are interested in the coordination chemistry of
unsaturated nitrogenous ligands and have extensively stud-
ied the chemistry of diazene HN@NH and HN@NR spe-
cies bonded to a transition metal [3–5]. A series of mono
and bis(diazene) complexes of the manganese [3], iron [4]
and cobalt [5] triads were therefore prepared and reactivity
2.1. General considerations
All synthetic work was carried out under an inert atmo-
sphere using standard Schlenk techniques or a Vacuum
Atmosphere dry-box. Once isolated, the complexes were
found to be relatively stable in air, but were stored under
an inert atmosphere at ꢀ25 °C. All solvents were dried over
appropriate drying agents, degassed on a vacuum line and
distilled into vacuum-tight storage flasks. The phosphites
*
Corresponding author. Tel.: +39 041 234 8555; fax: +39 041 234 8917.
E-mail address: albertin@unive.it (G. Albertin).
0020-1693/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2006.12.001

G. Albertin et al. / Inorganica Chimica Acta 361 (2008) 1744–1753
1745
R
N
R
N
solid slowly separated out from the resulting solution,
which was filtered and crystallized from CH2Cl2 and etha-
nol; yield from 61% to 83% [126 mg, 61% (1b), 164 mg,
68% (2b), 143 mg, 65% (3a), 168 mg, 72% (3b), 195 mg,
79% (3c), 215 mg, 83% (3d), 195 mg, 73% (4b)]. Anal. Calc.
for C60H61BMnNO7P2 (1b) (1035.84): C, 69.57; H, 5.94; N,
1.35. KM ¼ 52:2 Xꢀ1 molꢀ1 cm2. Found: C, 69.72; H, 5.90;
N, 1.28%. Anal. Calc. for C69H76BMnNO8P3 (2b)
(1206.03): C, 68.72; H, 6.35; N, 1.16. KM ¼ 54:5
Xꢀ1 molꢀ1 cm2. Found: C, 68.58; H, 6.30; N, 1.09%. Anal.
Calc. for C52H61BNO9P2Re (3a) (1103.01): C, 56.62; H,
5.57; N, 1.27. Found: C, 56.78; H, 5.62; N, 1.20%.
KM ¼ 54:7 Xꢀ1 molꢀ1 cm2. Anal. Calc. for C60H61BNO7-
P2Re (3b) (1167.10): C, 61.75; H, 5.27; N, 1.20. Found:
C, 61.54; H, 5.39; N, 1.12%. KM ¼ 51:6 Xꢀ1 molꢀ1 cm2.
Anal. Calc. for C68H61BNO5P2Re (3c) (1231.19): C,
66.34; H, 4.99; N, 1.14. Found: C, 66.45; H, 5.12; N,
1.04%. KM ¼ 53:9 Xꢀ1 molꢀ1 cm2. Anal. Calc. for
C76H61BNO3P2Re (3d) (1295.28): C, 70.47; H, 4.75; N,
1.08. KM ¼ 54:7 Xꢀ1 molꢀ1 cm2. Found: C, 70.28; H, 4.63;
N, 1.16%. Anal. Calc. for C69H76BNO8P3Re (4b)
(1337.29): C, 61.97; H, 5.73; N, 1.05. Found: C, 61.74; H,
5.65; N, 0.96%. KM ¼ 55:8 Xꢀ1 molꢀ1 cm2.
C
H
R
N
H
[M]
[M]
imine
diazene
Chart 1.
PPhðOEtÞ2 and PPh2OEt were prepared by the method of
Rabinowitz and Pellon [6], whereas PðOEtÞ3 was an
Aldrich product, purified by distillation under nitrogen.
Mn2ðCOÞ10 (Aldrich), Re2ðCOÞ10, RuCl3 ꢂ 3H2O, ðNH4Þ2-
OsCl6 and IrCl3 ꢂ 3H2O (Pressure Chem., USA) salts were
used without any further purification. Other reagents were
purchased from commercial sources (Aldrich, Fluka) in the
highest available purity and used as received. Infrared spec-
tra were recorded on Nicolet Magna 750 or Perkin–Elmer
Spectrum One FT-IR spectrophotometers. NMR spectra
(1H, 13C, 31P) were obtained on Bruker AC200 or
AVANCE 300 spectrometers at temperatures varying
1
between ꢀ90 and +30 °C, unless otherwise noted. H and
13C spectra are referred to internal tetramethylsilane, while
31P{1H} chemical shifts are reported with respect to 85%
H3PO4, with downfield shifts considered positive. The
COSY, HMQC and HMBC NMR experiments were per-
formed using their standard programs. The SwaN-MR
software package [7] was used to treat NMR data. The
conductivities of 10ꢀ3 M solutions of the complexes in
CH3NO2 at 25 °C were measured with a Radiometer
CDM 83 instrument. Elemental analyses were determi-
nated in the Microanalytical Laboratory of the Diparti-
mento di Scienze Farmaceutiche of the University of
Padova (Italy).
2.2.2. [MH(g1-NH@CPh2){P(OEt)3}4]BPh4 (5, 6)
[M@Ru (5), Os (6)]
An equimolar amount of triflic acid (HOTf) (0.2 mmol,
18 lL) was added to a solution of the appropriate dihy-
dride MH2½PðOEtÞ3ꢁ4 (0.2 mmol) in 10 mL of toluene
cooled to ꢀ196 °C. The solution was allowed to reach
room temperature and then stirred for 1 h. An excess of
benzophenone imine Ph2C@NH (1.6 mmol, 0.27 mL) was
added and the reaction mixture stirred for about 20 h.
The solvent was removed under reduced pressure to give
an oil which was triturated with ethanol containing an
excess of NaBPh4 (0.5 mmol, 171 mg). A white solid slowly
separated out from the resulting solution which was filtered
and crystallized from CH2Cl2 and ethanol [190 mg, 75%
(5), 214 mg, 79% (6)]. Anal. Calc. for C61H92BNO12P4Ru
(5) (1267.17): C, 57.82; H, 7.32; N, 1.11. Found: C,
57.67; H, 7.43; N, 1.17%. KM ¼ 50:4 Xꢀ1 molꢀ1 cm2. Anal.
Calc. for C61H92BNO12OsP4 (6) (1356.30): C, 54.02; H,
6.84; N, 1.03. Found: C, 54.19; H, 6.76; N, 1.08%.
KM ¼ 54:9 Xꢀ1 molꢀ1 cm2.
2.2. Synthesis of complexes
The hydride complexes MHðCOÞ3P2, MHðCOÞ2P3
[M = Mn, Re; P = P(OEt)3, PPh(OEt)2, PPh2OEt, PPh3],
MH2P4 ½M@Ru,Os;P@PðOEtÞ3ꢁ, IrHCl2LðPPh3Þ2, IrH-
Cl2LðAsPh3Þ2 [L@PðOEtÞ3 and PPhðOEtÞ2] and IrH2Cl-
ðPPh3Þ3 were prepared following the reported methods
[4d,5a,8–10].
2.2.1. [M(g1-NH@CPh2)(CO)nP5ꢀn]BPh4 (1–4)
[M@Mn (1, 2), Re (3, 4); P@P(OEt)3 (a), PPh(OEt)2
(b), PPh2OEt (c), PPh3 (d); n = 3 (1, 3), 2 (2, 4)]
An equimolar amount of triflic acid (HOTf) (0.2 mmol,
18 lL) was added to a solution of the appropriate hydride
MHðCOÞnP5ꢀn (0.2 mmol) in 7 mL of toluene cooled to
ꢀ196 °C. The reaction mixture was brought to room tem-
perature, stirred for 1 h and then an excess of benzophe-
none imine ðPh2C@NH, 1.6 mmol, 27 lL) was added.
The resulting solution was stirred for about 20 h and then
the solvent was removed under reduced pressure to give an
oil which was triturated with ethanol (2 mL) containing an
excess of NaBPh4 (0.45 mmol, 154 mg). A yellow or white
2.2.3. [Ru(g1-NH@CPh2)2{P(OEt)3}4](BPh4)2 (7)
Triflic acid (0.2 mmol, 18 lL) was added to a solution of
RuH2½PðOEtÞ3ꢁ4 (0.153 g, 0.2 mmol) in 10 mL of toluene
cooled to ꢀ196 °C. The solution was brought to 0 °C, stir-
red for 2 h and then cooled again to ꢀ196 °C. Triflic acid
was added (0.2 mmol, 18 lL) and the reaction mixture,
brought to room temperature, stirred for about 90 min.
An excess of benzophenone imine Ph2C@NH (2.0 mmol,
0.34 mL) was added and the reaction mixture stirred for
about 20 h. The solvent was removed under reduced pres-
sure to give an oil which was triturated with ethanol
(2 mL) containing an excess of NaBPh4 (0.8 mmol,

1746
G. Albertin et al. / Inorganica Chimica Acta 361 (2008) 1744–1753
0.274 g). A white solid separated out which was filtered and
crystallized from CH2Cl2 and ethanol (265 mg, 75%). Anal.
Calc. for C98H122B2N2O12P4Ru (1766.63): C, 66.63; H,
6.96; N, 1.59. KM ¼ 125 Xꢀ1 molꢀ1. Found: C, 66.49; H,
7.05; N, 1.49%.
ꢀ196 °C. The reaction mixture was brought to room tem-
perature, stirred for 20 h, and then the solvent removed
under reduced pressure. The oil obtained was triturated
with ethanol containing an excess of NaBPh4 (0.24 mmol,
82 mg). A yellow solid slowly separated out from the solu-
tion, which was filtered and crystallized from CH2Cl2 and
ethanol (123 mg, 69%). Anal. Calc. for C91H78BIrNP3
(1481.58): C, 73.77; H, 5.31; N, 0.95. Found: C, 73.61; H,
2.2.4. [Os(j1-OTf)(g1-NH@CPh2){P(OEt)3}4]BPh4 (8)
Methyltriflate (CH3OTf, 0.18 mmol, 20 lL) was added
to a solution of the dihydride OsH2½PðOEtÞ3ꢁ4 (0.18 mmol,
154 mg) in toluene (7 mL) cooled to ꢀ196 °C. The reaction
mixture was brought to room temperature, stirred for 1 h
and then cooled again to ꢀ196 °C. Triflic acid (0.18 mmol,
16 lL) was added and the reaction mixture, brought to
room temperature, stirred for about 90 min. An excess of
benzophenone imine Ph2C@NH (1.8 mmol, 0.30 mL) was
added and the resulting solution stirred for about 20 h.
The solvent was removed under reduced pressure to give
an oil which was triturated with ethanol (2 mL) containing
an excess of NaBPh4 (0.72 mmol, 0.25 g). A white solid
slowly separated out, which was filtered and crystallized
from CH2Cl2 and ethanol (168 mg, 62%). Anal. Calc. for
C62H91BF3NO15OsP4S (1504.36): C, 49.50; H, 6.10; N,
0.93. Found: C, 49.34; H, 6.17; N, 0.99%. KM ¼ 56:7
5.19; N, 0.90%. KM ¼ 53:0 Xꢀ1 molꢀ1
.
2.2.8. [Re{(CH3)2CHNH2}(CO)2{PPh(OEt)2}3] BPh4
(12)
An equimolar amount of triflic acid (HOTf) (0.15 mmol,
13 lL) was added to a solution of ReHðCOÞ2½PPhðOEtÞ ꢁ
(0.15 mmol, 125 mg) in toluene (10 mL) cooled to ꢀ196 °2C3.
The reaction mixture was brought to room temperature,
stirred for about 1 h and then an excess of the amine
ðCH3Þ2CHNH2 (1.2 mmol, 102 lL) was added. The solu-
tion was stirred for 20 h and then the solvent removed
under reduced pressure. The oil obtained was triturated
with ethanol (2 mL) containing an excess of NaBPh4
(0.3 mmol, 103 mg). A white solid separated out which
was filtered and crystallized from CH2Cl2 and ethanol
(140 mg, 77%). Anal. Calc. for C59H74BNO8P3Re
(1215.17): C, 58.32; H, 6.14; N, 1.15. Found: C, 58.45; H,
Xꢀ1 molꢀ1
.
2.2.5. IrHCl(g1-NH@CPh2)L(PPh3)2 (9) [L@P(OEt)3
(a), PPh(OEt)2 (b)]
6.25; N, 1.06%. KM ¼ 56:9 Xꢀ1 molꢀ1
.
A slight excess of benzophenone imine Ph2C@NH
(0.13 mmol, 22 lL) was added to a solution of the appro-
priate hydride IrHCl2LðPPh3Þ2 (0.12 mmol) in 7 mL of
CH2Cl2 and the solution stirred for 20 h. The solvent was
removed under reduced pressure giving an oil which was
triturated with ethanol (2 mL) containing an excess of
NaBPh4 (0.24 mmol, 82 mg). A yellow solid slowly sepa-
rated out which was filtered and crystallized from
CH2Cl2 and ethanol [112 mg, 66% (9a), 122 mg, 70%
(9b)]. Anal. Calc. for C79H77BClIrNO3P3 (9a) (1419.89):
C, 66.83; H, 5.47; Cl, 2.50; N, 0.99. Found: C, 66.65; H,
5.61; Cl, 2.36; N, 1.06%. Anal. Calc. for C83H77-
BClIrNO2P3 (9b) (1451.93): C, 68.66; H, 5.35; Cl, 2.44;
N, 0.96. Found: C, 68.64; H, 5.46; Cl, 2.31; N, 0.89%.
2.2.9. [RuH(RNH2){P(OEt)3}4] BPh4 (13, 14)
[R@Ph2CH (13), (CH3)2CH (14)]
Triflic acid (0.13 mmol, 12 lL) was added to a solution
of the dihydride RuH2½PðOEtÞ3ꢁ4 (0.13 mmol, 100 mg) in
toluene (7 mL) cooled to ꢀ196 °C and the reaction mix-
ture, brought to 0 °C, was stirred for 1 h. An excess of
the appropriate amine (1 mmol) was added and the reac-
tion mixture stirred for 20 h. The solvent was removed
under reduced pressure to give an oil which was triturated
with ethanol (2 mL) containing an excess of NaBPh4
(0.40 mmol, 137 mg). A white solid slowly separated out
which was filtered and crystallized from CH2Cl2 and etha-
nol; yield between 65% and 78% [107 mg, 65% (13),
116 mg, 78% (14)]. Anal. Calc. for C61H94BNO12P4Ru
(13) (1269.19): C, 57.73; H, 7.46; N, 1.10. Found: C,
57.59; H, 7.40; N, 0.96%. KM ¼ 51:7 Xꢀ1 molꢀ1. Anal. Calc.
for C51H90BNO12P4Ru (14) (1145.05): C, 53.50; H, 7.92; N,
1.22. Found: C, 53.63; H, 7.98; N, 1.16%. KM ¼ 54:4
2.2.6. IrHCl(g1-NH@CPh2)L (AsPh3)2 (10)
[L@P(OEt)3 (a), PPh(OEt)2 (b)]
These complexes were prepared exactly like the related
compounds 9 using a reaction time of 24 h [132 mg, 73%
(10a), 142 mg, 77% (10b)]. Anal. Calc. for C79H77As2-
BClIrNO3P (10a) (1507.78): C, 62.93; H, 5.15; Cl, 2.35;
N, 0.93. Found: C, 62.74; H, 5.21; Cl, 2.40; N, 1.02%. Anal.
Calc. for C83H77As2BClIrNO2P (10b) (1539.83): C, 64.74;
H, 5.04; Cl, 2.30; N, 0.91. Found: C, 64.79; H, 5.13; Cl,
2.35; N, 0.87%.
Xꢀ1 molꢀ1
.
2.2.10. Oxidation reactions
The oxidation reactions were carried out at room and
low temperature (ꢀ30 °C) in CH2Cl2, using PbðOAcÞ4 as
a reagent. In a typical experiment, the solid sample of
amine complex 12–14 (0.2 mmol) was placed in a three-
necked 25-mL flask fitted with a solid-addition sidearm
containing PbðOAcÞ4 (0.2 mmol, 89 mg). The apparatus
was evacuated, CH2Cl2 (10 mL) was added, the solution
was cooled to ꢀ30 °C and PbðOAcÞ4 was added portion-
wise over 10–20 min to the cold stirring solution. The
2.2.7. [IrH2(g1-NH@CPh2) (PPh3)3]BPh4 (11)
A slight excess of Ph2C@NH (0.13 mmol, 22 lL) was
added to a solution of the hydride IrH2ClðPPh3Þ3
(0.12 mmol, 122 mg) in CH2Cl2 (7 mL) cooled to

G. Albertin et al. / Inorganica Chimica Acta 361 (2008) 1744–1753
1747
Ph
reaction mixture was then allowed to warm to 0 °C, stirred
+
Ph
C
P
M
P
exc.
C
NH
for 20 min and then the solvent was removed under
reduced pressure at 0 °C. The oil obtained was treated at
the same temperature with ethanol (2 mL) obtaining a
white solid, which was filtered and dried under vacuum.
P
H
N
MH(κ1-OTf)P4
Ph
P
Ph
H
M = Ru (5), Os (6).
5, 6 ( III )
3. Results and discussion
2+
Ph
H
Ph
Ph
C
P
3.1. Manganese, rhenium, ruthenium and osmium complexes
exc.
Ph
C
NH
N
Ph
P
[Ru(κ2-OTf)P4]+
Ru
C
Ph
Imine complexes of manganese and rhenium of the
½Mðg1-NH@CPh2ÞðCOÞnP5ꢀnꢁBPh4 (1–4) types were syn-
thesized by reacting triflate complexes Mðj1-OTfÞðCOÞn-
P5ꢀn with an excess of free imine, as shown in Scheme 1.
Triflates Mðj1-OTfÞðCOÞnP5ꢀn were generated in situ by
reacting hydride MHðCOÞnP5ꢀn species with 1 eq of triflic
acid at low temperature, as previously reported [8,9]. Sub-
stitution of the labile triflate ligand with the N-protio imine
Ph2C@NH gives the final complexes 1–4, which were sepa-
rated as BPh4 salts and characterized.
P
N
H
P
7 ( IV )
+
Ph
Ph
Ph
C
P
exc.
C
NH
P
OTf
N
[Os(κ2-OTf)P4]+
Os
P
Ph
P
H
8 ( V )
P = P(OEt)3
Substitution of the labile triflate ligand also allowed us
to prepare benzophenone imine complexes of ruthenium
and osmium, as shown in Scheme 2.
Scheme 2.
Thus, hydride-imine ½MHðg1-NH@CPh2ÞP4ꢁþ (5, 6)
At room temperature, substitution of the triflate does
not take place, whereas refluxing conditions caused some
decomposition, giving intractable mixtures of products.
In contrast with the N-protio Ph2C@NH imine, the N-
methyl imine does not yield the corresponding imine
½MꢁANðCH3Þ@CðHÞPh derivatives, probably owing to ste-
ric hindrance of the N-methyl group, which makes the
PhCðHÞ@NCH3 imine a poor coordinating ligand.
complexes of both ruthenium and osmium were obtained
from hydride-triflate MHðj1-OTfÞP4 precursors [11].
2þ
Instead, bis(imine) ½Mðg1-NH@CPh2Þ2P4ꢁ
derivatives
were prepared only in the case of ruthenium, because, with
osmium, the reaction of the j2-triflate ½Mðj2-OTfÞP4ꢁþ cat-
ion with an excess of imine always gave imine-triflate
½Osðj1-OTfÞðg1-NH@CPh2ÞP4ꢁþ complexes 8.
The easy synthesis of benzophenone imine complexes 1–
8 also prompted us to prepare complexes containing
N-substituted imine R1ðR2ÞC@NðRÞ. We therefore
reacted the triflate Mðj1-OTfÞðCOÞnP5ꢀn ðM ¼ Mn; ReÞ
and MHðj1-OTfÞP4 ðM ¼ Ru; OsÞ precursors with the N-
methyl PhCðHÞ@NCH3 imine in various conditions, but
no imine complexes were obtained (Scheme 3).
Protio-imine complexes of transition metals have previ-
ously been prepared following methods not applying sub-
stitution of a labile ligand. Taube et al. [2a] prepared an
imine complex from the reaction of coordinate NH3 with
acetone, and Templeton et al. [2d] prepared from the
reduction of coordinate acetonitrile. Instead, Gladysz
et al. [2e] prepared a rhenium imine derivative from the
reaction of a coordinate nitrile, first with Grignard’s
reagent and then with triflic acid.
+
We also attempted to prepare imine complexes follow-
ing a new method, involving oxidation of the coordinate
amine. For this purpose, we prepared some amine com-
plexes of rhenium and ruthenium and studied their oxida-
tion reactions with PbðOAcÞ4 [12] (Scheme 4).
Ph
Ph
C
P
exc.
C
NH
OC
OC
CO
N
M(κ1-OTf)(CO)3P2
Ph
M
Ph
P
H
1, 3 ( I )
+
exc. PhC(H)=NCH3
Ph
Ph
M(κ1-OTf)(CO)nP5-n
Ph
C
P
M
P
exc.
C
NH
OC
OC
P
M(κ1-OTf)(CO)2P3
M = Mn, Re
N
Ph
H
2, 4 ( II )
exc. PhC(H)=NCH3
MH(κ1-OTf)P4
M = Mn (1,2), Re (3, 4); P = P(OEt)3, PPh(OEt)2, PPh2OEt
M = Ru, Os
Scheme 1.
Scheme 3.

1748
G. Albertin et al. / Inorganica Chimica Acta 361 (2008) 1744–1753
+
P
OC
OC
NH2CH(CH3)2
CO
(CH3)2C(H)NH2
Pb(OAc)4
-30 ˚C
decomp.
products
Re(κ1-OTf)(CO)3P2
Re
P
12
+
P
P
P
H
R2C(H)NH2
Pb(OAc)4
RuH(κ1-OTf)P4
Ru
NH2C(H)R2
P
13, 14
R = CH3 (13), Ph (14).
Scheme 4.
Unfortunately, results show that this method was not
suitable for our complexes, and no imine complexes were
obtained using PbðOAcÞ4 as an oxidant. Ruthenium com-
plexes 13, 14 do not react with PbðOAcÞ4 in any conditions,
and the starting amine complexes were recovered
unchanged after several hours of reaction. Other oxidizing
reagents such as MnO2, PbO2 and H2O2 were used with
complexes 13, 14, but here too no reactions were observed.
However, the rhenium ½RefðCH3Þ2CðHÞNH2gðCOÞ2-
P3ꢁþ cation 12 reacted with an excess of PbðOAcÞ4 at low
temperature (ꢀ30 °C) to give a yellow solution, from which
an oily product was isolated, although its 1H NMR spectra
did not indicate the presence of any imine complex. There-
fore, it seems that only by substitution of a labile ligand
can the preparation of benzophenone imine complexes take
place for the phosphite-containing Mn, Re, Ru and Os
metal derivatives.
Imine complexes 1–8 are yellow or white solids, stable in
air and in solution of polar organic solvents, in which they
behave as 1:1 electrolytes, except for bis(imine) ½Ruðg1-
NH@CPh2Þ2P4ꢁðBPh4Þ2 complex 7, which behaves like a
2:1 electrolyte [13]. Analytical and spectroscopic data
(Table 1) support the proposed formulation.
The IR spectra of tricarbonyl ½Mðg1-NH@CPh2Þ-
ðCOÞ3P2ꢁBPh4 complexes (1, 3) of both Mn and Re show
three bands in the mCO region, one of medium intensity
and two strong, suggesting a mer arrangement of the three
carbonyl ligands [14]. The spectra also show a medium-
intensity band at 3226–3204 cmꢀ1 attributed to the mNH
of the imine ligand.
lence of the two phosphite ligands. The 31P NMR spectra
of the related manganese complexes 1 are broad at room
temperature, but resolve into a sharp singlet at ꢀ80 °C,
again fitting the magnetic equivalence of the two phosphite
ligands. On the basis of these data, a mer-trans geometry (I,
Scheme 1) may be proposed for our tricarbonyl derivatives.
The IR spectra of dicarbonyl ½Mðg1-NH@CPh2Þ-
ðCOÞ2P3ꢁBPh4 (2, 4) complexes show two strong absorp-
tions in the mCO region at 1983–1902 cmꢀ1, suggesting a
cis arrangement of the two carbonyl ligands. However,
these two CO groups are not magnetically equivalent
since the 13C NMR spectra of the complexes show two
well-separated multiplets at 223.4 and 215.8 ppm for 2b
and at 196.4 and 192.9 for 4b. The 31P{1H} NMR spectra
of the dicarbonyl derivatives of manganese 2b change as
the temperature is lowered and, at ꢀ70 °C, appear as an
A2B multiplet simulable with the parameters reported in
Table 1. In the temperature range between +20 and
ꢀ80 °C, also the 31P{1H} NMR spectra of the related rhe-
nium dicarbonyl complex 4b are AB2 multiplets, indicat-
ing the magnetic equivalence of two phosphites, unlike
the third. On the basis of these data, a mer-cis geometry
of type II (Scheme 1) may be proposed for the dicarbonyl
imine derivatives.
Comparisons with previous results from our laboratory
[3] highlight the interesting ability of the mixed-ligand
MðCOÞnP5ꢀn fragment (M ¼ Mn, Re) with phosphite and
carbonyl to coordinate unsaturated nitrogenous ligands.
In fact, 1,2-diazene ½Mðg1-NH@NHÞðCOÞnP5ꢀnꢁBPh4 and
aryldiazene ½Mðg1-NH@NArÞðCOÞnP5ꢀnꢁBPh4 complexes
were previously prepared for both manganese [3a,3d] and
rhenium [3b,3e] and are stable and isolable like the benzo-
phenone imine derivatives 1–4 reported here. In addition,
the simplest imine ligand, CH2@NH, was stabilized for
the first time, using right the rhenium fragment
ReðCOÞnp5ꢀn to give the related ½Reꢁ-g1-NH@CH2 com-
plex [15]. Therefore, the ability of ReðCOÞnP5ꢀn fragments
to coordinate an imine group is confirmed when the benzo-
phenone imine ligand is used.
However, the presence of the Ph2C@NH group in the
1
complexes was confirmed by the H NMR spectra, with a
slightly broad signal at 9.55–8.80 ppm due to the NH pro-
ton resonances of the imine ligand. This signal, in an
HMBC experiment for compound 3b, is also correlated
with a triplet at 183.2 ppm ðJCP ¼ 2 HzÞ, attributed to
the C@NH carbon resonance of the imine, in agreement
with the proposed formulation.
In the temperature range between +20 and ꢀ80 °C, the
31P NMR spectra of ½Reðg1-NH@CPh2ÞðCOÞ3P2ꢁBPh4
complexes 3 are sharp singlets, fitting the magnetic equiva-
The IR spectra of the imine ½MHðg1-NH@CPh2ÞP4ꢁ-
BPh4 complexes of ruthenium and osmium 5 and 6 show

G. Albertin et al. / Inorganica Chimica Acta 361 (2008) 1744–1753
1749
Table 1
IR and NMR data for all complexes
Compound
IRa (cmꢀ1
)
Assgnt 1H NMRb,c d (J, Hz) Assgnt
Spin system 31P{1H} NMRb,d d (J, Hz)
1b
2b
½Mnðg1-NH@CPh2ÞðCOÞ3fPPhðOEtÞ2g2ꢁBPh4
½Mnðg1-NH@CPh2ÞðCOÞ2fPPhðOEtÞ2g3ꢁBPh4
3223 m
2065 m
1986 s
1940 s
mH
mO
9.05 s
4.00 m
1.23 t
@NH
CH2
CH3
A2
A2
158 br
160.4 s
e
f
3226 m
1968 s
1902 s
mNH
mCO
9.93 d
JPH ¼ 10
3.77 m
3.49 m
1.18 t
@NH
CH2
CH3
A2Be
dA 190.4
dB 177.6
JAB ¼ 75:0
1.09 t
3a
3b
3c
3d
4b
½Reðg1-NH@CPh2ÞðCOÞ3fPðOEtÞ3g2ꢁBPh4
3215 m
2072 m
1971 s
1929 s
mNH
mCO
9.55 s
4.05 m
1.32 t
@NH
CH2
CH3
A2
110.5 s
133.2 s
107.5 s
13.8 s
g
½Reðg1-NH@CPh2ÞðCOÞ3fPPhðOEtÞ2g2ꢁBPh4
½Reðg1-NH@CPh2ÞðCOÞ3ðPPh2OEtÞ2ꢁBPh4
½Reðg1-NH@CPh2ÞðCOÞ3ðPPh3Þ2ꢁBPh4
3204 m
2065 m
1980 s
1940 s
mNH
mCO
9.28 s, br
4.04 m
1.38 t
@NH
CH2
CH3
A2
3215 w
2056 m
1960 s
1934 s
mNH
mCO
9.18 s
3.54 m
1.18 t
@NH
CH2
CH3
A2
3211 w
2067 m
1966 s
1914 s
mNH
8.80 s, br
@NH
A2
nuCO
h
½Reðg1-NH@CPh2ÞðCOÞ2fPPhðOEtÞ2g3ꢁBPh4
3240 m
1983 s
1902 s
mNH
mCO
9.95 d, br
JPH ¼ 8
4.00–3.55 m
1.33 t
@NH
AB2
dA 135.9
dB 134.1
JAB ¼ 33:5
CH2
CH3
1.21 t
1.15 t
5
½RuHðg1-NH@CPh2ÞfPðOEtÞ3g4ꢁBPh4
3285 m
1911 w
mNH
mRuH
10.40 d, br
JPH ¼ 6:8
4.25-3.70 m
1.32 t
1.21 t
1.13 t
@NH
AB2C
dA 148.6
dB 142.9
dC 136.8
JAB ¼ 63:5
JAC ¼ 40:9
JBC ¼ 44:1
CH2
CH3
ꢀ7.11 to ꢀ8.18 m
RuH
6
7
8
½OsHðg1-NH@CPh2ÞfPðOEtÞ3g4ꢁBPh4
½Ruðg1-NH@CPh2Þ2fPðOEtÞ3g4ꢁðBPh4Þ2
½Osðj1-OTfÞðg1-NH@CPh2ÞfPðOEtÞ3g4ꢁBPh4
3219 m
1987 w
mNH
mOsH
10.87 d, br
4.25–3.00 m
1.27 t
1.16 t
1.12 t
@NH
CH2
CH3
A2BC
ABC2
A2BC
dA 104.3
dB 101.6
dC 96.4
JAB ¼ 32:9
JAC ¼ 44:2
JBC ¼ 28:8
ꢀ8.22 to ꢀ9.07 m
OsH
3223 m
mNH
10.46 s, br
4.08 m
1.27 t
@NH
CH2
CH3
dA 129.5
dB 129.2
dC 119.6
JAB ¼ 37:7
JAC ¼ 59:1
JBC ¼ 60:8
1.25 t
3207 m
mNH
10.93 s, br
4.06 m
3.90 m
1.31 t
1.27 t
1.25 t
@NH
CH2
dA 83.8
dB 76.7
dC 75.6
CH3
JAB ¼ 42:5
JAC ¼ 42:2
JBC ¼ 45:6
(continued on next page)

1750
G. Albertin et al. / Inorganica Chimica Acta 361 (2008) 1744–1753
Table 1 (continued)
Compound
IRa (cmꢀ1
)
Assgnt 1H NMRb,c d (J, Hz) Assgnt
Spin system 31P{1H} NMRb,dd (J, Hz)
9a
½IrHClðg1-NH@CPh2ÞfPðOEtÞ3gðPPh3Þ2ꢁBPh4
3243 m
2236 w
mNH
mIrH
8.55 s, br
3.16 qnt
0.67 t
AB2X spin syst
ðX ¼ 1HÞ
dX ꢀ18.75
JAX ¼ 10
JBX ¼ 20
@NH
CH2
CH3
IrH
AB2
dA 52.9
dB ꢀ1.1
JAB@30:1
9b
½IrHClðg1-NH@CPh2ÞfPPhðOEtÞ2gðPPh3Þ2ꢁBPh4
3238 m
2243 w
mNH
mIrH
9.04 s, br
3.41 m
3.09 m
@NH
CH2
AB2
dA 80.7
dB ꢀ2.6
JAB ¼ 23:0
0.72 t
CH3
IrH
AB2X spin syst
ðX ¼ 1HÞ
dX ꢀ19.25
JAX ¼ 10
JBX ¼ 22
10a ½IrHClðg1-NH@CPh2ÞfPðOEtÞ3gðAsPh3Þ2ꢁBPh4
3250 m
mNH
9.52 d
@NH
A
18.7 s
JPH ¼ 2
3.54 qnt
0.96 t
CH2
CH3
IrH
ꢀ19.56 d
JPH ¼ 22
10b ½IrHClðg1-NH@CPh2ÞfPPhðOEtÞ2gðAsPh3Þ2ꢁBPh4 3217 m
mNH
mIrH
9.10 s
3.56 m
0.68 t
@NH
CH2
CH3
IrH
A
82.6 s
2243 w
ꢀ19.82 d
JPH ¼ 24
11
½IrH2ðg1-NH@CPh2ÞðPPh3Þ3ꢁBPh4
3258 m
2170 w
mNH
mIrH
10.61 s
@NH
IrH2
A2B
dA 2.6
A2BXY spin syst
ðX; Y ¼ 1HÞ
dX ꢀ12.21
dY ꢀ19.88
JXY ¼ 5:1
dB ꢀ0.2
JAB ¼ 12:6
JXA ¼ 20:1
JXB ¼ 134:1
JYA ¼ 20:4
JYB ¼ 10:9
12
13
½RefðCH3Þ2CðHÞNH2gðCOÞ2fPPhðOEtÞ2g3ꢁBPh4
½RuHðPh2CðHÞNH2ÞfPðOEtÞ3g4ꢁBPh4
3298 m
3246 m
1956 s
1877 s
mNH
mCO
4.00 m
2.71 m
2.37 br
1.31 t
CH2
CH
NH2
CH3 phos
ðCH3Þ2CH
CH
CH2
CH3
A2
140.5 s
0.90 d
3323 m
3267 m
1870 m
mNH
4.88 m
4.10–3.60 m
1.21 t
AB2C
dA 148.7
dB 142.2
dC 135.6
mRuH
1.17 t
1.13 t
ꢀ7.40 to ꢀ8.44 m
JAB ¼ 64:9
JAC ¼ 34:8
JBC ¼ 48:0
RuH
14
½RuHfðCH3Þ2CðHÞNH2gfPðOEtÞ3g4ꢁBPh4
3342 m
3283 m
1887 m
mNH
4.15–3.80 m
2.64 m
2.47 s, br
CH2
CH
NH2
AB2C
dA 149.1
dB 142.9
dC 137.0
mRuH
1.35–1.12 m
1.12 d
ꢀ7.51 to ꢀ8.55 m
CH3 phos
ðCH3Þ2CH
RuH
JAB ¼ 64:1
JAC ¼ 36:5
JBC ¼ 46:9
a
In KBr pellets.
b
c
d
e
f
In CD2Cl2 at 25 °C.
Phenyl proton resonances of phosphite ligands between 7.70 and 7.20 ppm are omitted.
Positive shifts downfield from 85% H3PO4.
At ꢀ70 °C.
13C{1H} NMR, d: 223.4, 215.8 (m, CO), 187.4 (br, C@N), 160–121 (m, Ph), 66.3, 65.7 (d, CH2), 16.5, 16.2 (s, br, CH3).
g
h
13C{1H} NMR, d: 191.8 (t, JCP ¼ 8), 190.1 (t, JCP ¼ 10) (CO), 183.2 (t, JCP ¼ 2, C@N), 155–122 (m, Ph), 62.8 (m, CH2), 16.1 (m, CH3).
13C{1H} NMR, d: 196.4 (m), 192.9 (dt) (CO), 184.8 (dt, C@N), 136–122 (m, Ph), 65.7 (d), 63.5 (dt) ðCH2Þ, 16.7, 16.3 (d, CH3).

G. Albertin et al. / Inorganica Chimica Acta 361 (2008) 1744–1753
1751
a medium-intensity band at 3285–3219 cmꢀ1 attributed to
exc. Ph2C=NH
IrHCl2L(PPh3)2
IrHCl2L(AsPh3)2
[IrHCl(η1-NH=CPh2)L(PPh3)2]+
the mNH of the imine ligand, and a weak band at 1987–
9
1
1911 cmꢀ1 due to the mMH of the hydride group. The H
NMR spectra confirm the presence of both imine and
hydride ligands, showing the slightly broad signal of the
NH proton resonance of the coordinate Ph2C@NH species
at 10.87–10.40 ppm and a multiplet of the Hꢀ ligand
between ꢀ7.11 and ꢀ9.07 ppm. In the temperature range
between +20 and ꢀ80 °C, the 31P NMR spectra of com-
plexes 5 and 6 appear as AB2C or A2BC multiplets, indicat-
ing the mutually cis position of the hydride and imine
ligands. On the basis of these data, a geometry of type
III (Scheme 2) may be proposed for hydride-imine com-
plexes 5 and 6.
exc. Ph2C=NH
[IrHCl(η1-NH=CPh2)L(AsPh3)2]+
10
L = P(OEt)3 (a), PPh(OEt)2 (b).
Scheme 5.
exc. Ph2C=NH
IrH2Cl(PPh3)3
[IrH2(η1-NH=CPh2)(PPh3)3]+
11
A cis arrangement of the imine and triflate ligands, as in
type V, geometry can also be proposed for the
½Osðj1-OTfÞðg1-NH@CPh2ÞP4ꢁBPh4 complex 8, whose
31P NMR spectrum appears as an A2BC multiplet simula-
ble with the parameters reported in Table 1.
Scheme 6.
The benzophenone imine Ph2C@NH substitutes only one
chloride in the starting complex, giving cationic compounds
9, 10 in good yields. Substitution of the Clꢀ ligand also takes
place in the dihydride IrH2ClðPPh3Þ3 species (Scheme 6),
giving the imine ½IrH2ðg1-NH@CPh2Þ- ðPPh3Þ3ꢁþ (11)
derivatives.
The IR spectrum of the bis(imine) ½Ruðg1-NH@
CPh2Þ2P4ꢁðBPh4Þ2 (7) derivative shows the mNH band of
1
the imine at 3223 cmꢀ1, whereas the H NMR spectrum
exhibits the NH proton resonance as a slightly broad signal
at 10.46 ppm. Surprisingly, the 31P NMR spectra give an
asymmetric ABC2 pattern, which does not change in profile
when sample temperature is lowered from +20 to ꢀ80 °C.
This ABC2-type 31P spectrum is unexpected, because either
a symmetric A2B2 or an A4-type spectrum is expected for
octahedral bis(imine) complex 7. However, the difference
in chemical shift between nuclei A and B of our ABC2 spec-
trum is very small (Table 1) and the two JAC and JBC values
are very similar, suggesting that a cis geometry (IV) is
probably present in our bis(imine) complex 7, but the steric
requirements of the two benzophenone imines cause some
distortion on the molecule. Thus, only two phosphines
are magnetically equivalent, giving an ABC2 spectrum for
the complex.
Results in synthesizing imine complexes 1–8 using tri-
flate species as starting materials prompted us to use this
method also for iridium IrHCl2LðPPh3Þ2 precursors. Treat-
ment of IrHCl2LðPPh3Þ2 complexes with Brønsted acids
HY ðY ¼ BF4ꢀ; OTfꢀÞ proceeded with the evolution of
H2 and formation of unsaturated ½IrCl2LðPPh3Þ ꢁþ cations
2
or neutral IrðYÞCl2LðPPh3Þ2 intermediates [5a]. However,
reaction of these intermediates with Ph2C@NH gave a mix-
ture of compounds which were not separate in pure form
(Scheme 7). The NMR spectra of the reaction products
indicated not only other compounds, but also at least
two species containing coordinate imine.
This method was therefore abandoned, owing to the for-
mation of too many species. Substitution of the chloride
ligand in IrHCl2LðPPh3Þ2 or IrH2ClðPPh3Þ3 complexes
seemed to be the most suitable method for synthesizing
mono-imine derivatives of iridium. This method is also
important because it allowed the synthesis of the first
examples, to the best of our knowledge, of N-proton imine
complexes of iridium [1,2].
Imine complexes of ruthenium and osmium are rare
and, apart from Taube’s pentamine ½OsðNH3Þ5fNH@
CðHÞCH3gꢁ2þ complex [2a], only a few examples are known
[2f,2g]. The use of phosphite-containing MHP4 and MP4
(M ¼ Ru and Os) metal fragments allows easy synthesis
of both mono and bis(benzophenone imine) complexes 5–
8. It is worth noting that the same MHP4 and MP4 frag-
ments were shown to be able to stabilize aryldiazene
ligands, giving ½MHðNH@NArÞP4ꢁþ and ½MðNH@NArÞ2-
[IrCl2L(PPh3)2]+Y-
– H2
2þ
or
IrHCl2L(PPh3)2 + HY
P4ꢁ derivatives [4b,4c,4f], highlighting the fact that a
Ir(Y)Cl2L(PPh3)2
metal fragment that coordinates diazene is also able to bind
imine species, giving stable derivatives.
Ph
Ph
exc.
C
NH
3.2. Iridium complexes
MIXTURE
of
PRODUCTS
Hydride IrHCl2LðPPh3Þ2 and IrHCl2LðAsPh3Þ2 com-
plexes react with a slight excess of Ph2C@NH to give
mono-imine ½IrHClðg1-NH@CPh2ÞLðPPh3Þ2ꢁþ (9) and
½IrHClðg1-NH@CPh2ÞLðAsPh3Þ2ꢁþ (10) cations, which
were separated as BPh4 salts and characterized (Scheme 5).
L = P(OEt)3, PPh(OEt)2; HY = HBF4•Et2O or HOTf
Scheme 7.

1752
G. Albertin et al. / Inorganica Chimica Acta 361 (2008) 1744–1753
H
+
+
+
Ph
C
Ph
C
PA
Ir
P
P
HY
PB
N
P
H
N
P
N
Ph
Ir
Ir
C
H X
Ph
Cl
Ph
H
Cl
PA
P
P
Ph
H
H
(VIII)
(VI)
(VII)
Chart 2.
Chart 3.
Imine complexes 9–11 are yellow solids, stable in air and
in solution of polar organic solvents, where they behave as
1:1 electrolytes [13]. Analytical and spectroscopic data
(Table 1) support the proposed formulation.
whether amine can form in mild conditions. However, at
room temperature no reaction was observed with H2 at
1 atm and the imine complexes were recovered unchanged
after 24 h of reaction. Complexes 1–11 were also unreactive
toward both substitution of ligands and deprotonation of
the imine hydrogen atom by NEt3 or LiOH, highlighting
the considerable stability of the coordinate imine group.
The IR spectra of the imine complexes of iridium
IrHClðg1-NH@CPh2ÞLðPPh3Þ2 (9) show a medium-inten-
sity band between 3243 and 3238 cmꢀ1, attributed to the
mNH of the imine group, and a weak absorption at 2243–
2236 cmꢀ1, due to the mIrH of the hydride ligand. The pres-
ence of both these ligands was confirmed by proton NMR
spectra, which show a slightly broad singlet at 9.04–
8.55 ppm, due to imine proton resonance. In addition to
the signals of the phosphine and the BPh4 anion, a multi-
plet also appears in the spectra at ꢀ18.75 (9a) and
ꢀ19.25 (9b) ppm, attributed to the hydride ligand. As the
31P{1H} NMR spectra are AB2 multiplets, the hydride pat-
tern in the proton spectra may be simulated with an AB2X
model ðX ¼ 1HÞ using the parameters of Table 1. The val-
ues of the two JPH observed in the spectra are comparable,
suggesting that the hydride is in a mutually cis position
with respect to all the phosphorus nuclei of the phosphine.
However, these data do not allow us unambiguously to
assign one of the two geometries, VI or VII, to complexes
9 (Chart 2).
4. Conclusions
This paper describes the synthesis of a series of mono
and bis(benzophenone imine) complexes of manganese,
rhenium, ruthenium and osmium by substituting a labile
triflate ligand on appropriate precursors. The first exam-
ples of benzophenone imine complexes of iridium were also
prepared, and a geometry in solution was established.
Acknowledgements
The financial support of MIUR (Rome) – PRIN 2004 –
is gratefully acknowledged. We thank Daniela Baldan for
technical assistance.
References
The mNH band at 3250–3217 cmꢀ1 was also observed in
the arsine IrHClðg1-NH@CPh2ÞLðAsPh3Þ2 (10) complexes,
whose 1H NMR spectra show the broad NH proton signal
of the imine at 9.52–9.10 ppm. Instead, the hydride signal
appears as a doublet near ꢀ19 ppm, due to coupling with
the only phosphite ligand present on the complex, in agree-
ment with the proposed formulation.
[1] (a) G. Wilkinson, R.D. Gillard, J.A. McCleverty (Eds.), Com-
prehensive Coordination Chemistry, Pergamon Press, Oxford,
UK, 1987;
(b) J.A. McCleverty, T.J. Meyer (Eds.), Comprehensive Coordi-
nation Chemistry II, Elsevier, Pergamon, Oxford, UK, 2003.
[2] (a) W.D. Harman, H. Taube, Inorg. Chem. 27 (1988) 3261;
(b) B.S. McGilligan, T.C. Wright, G. Wilkinson, M. Motevalli, M.B.
Hursthouse, J. Chem. Soc., Dalton Trans. (1988) 1737;
(c) R.A. Michelin, R. Bertani, M. Mozzon, G. Bombieri, F.
Benetollo, R. Angelici, Organometallics 10 (1991) 1751;
(d) S.G. Feng, J.L. Templeton, Organometallics 11 (1992) 1295;
(e) D.A. Knight, M.A. Dewey, G.A. Stark, B.K. Bennett, A.M. Arif,
J.A. Gladysz, Organometallics 12 (1993) 4523;
The IR spectrum of the dihydride ½IrH2ðg1-NH@
CPh2ÞðPPh3Þ3ꢁBPh4 (11) complex shows a medium-inten-
sity band at 3258 cmꢀ1, attributed to the mNH of the imine
group, and a weak absorption at 2170 cmꢀ1, due to the mIrH
1
of the hydride ligand. The H NMR spectrum shows a
slightly broad signal at 10.61 ppm, attributed to NH imine
proton resonance, and a complicated multiplet between
ꢀ11 and ꢀ21 ppm, attributed to the two hydride ligands.
As the 31P{1H} NMR spectrum appears as an A2B pattern,
the hydride multiplet may be simulated with an A2BXY
model ðX@H;Y@HÞ using the parameters of Table 1.
The two hydride ligands are magnetically non-equivalent
and, on the basis of the 31P spectra, a geometry of type VIII
(Chart 3) may be proposed for our imine-dihydride
complex 11.
(f) M.A. Esteruelas, F.J. Lahoz, A.M. Lopez, E. Onate, L.A. Oro,
˜
Organometallics 14 (1995) 2496;
(g) F. Bustelo, M. Jimenez-Tenorio, M.C. Puerta, P. Valerga, J.
Chem. Soc., Dalton Trans. (1999) 2399.
[3] (a) G. Albertin, S. Antoniutti, A. Bacchi, E. Bordignon, F. Busatto,
G. Pelizzi, Inorg. Chem. 36 (1997) 1296;
(b) G. Albertin, S. Antoniutti, A. Bacchi, G.B. Ballico, E. Bordignon,
G. Pelizzi, M. Ranieri, P. Ugo, Inorg. Chem. 39 (2000) 3265;
(c) G. Albertin, S. Antoniutti, A. Bacchi, E. Bordignon, F. Miani,
G. Pelizzi, Inorg. Chem. 39 (2000) 3283;
(d) G. Albertin, S. Antoniutti, E. Bordignon, G. Perinello, J.
Organomet. Chem. 625 (2001) 217;
Reactivity studies of imine complexes 9–11 toward
hydrogenation reactions were made, in order to verify
(e) G. Albertin, S. Antoniutti, M.T. Giorgi, Eur. J. Inorg. Chem.
(2003) 2855;

G. Albertin et al. / Inorganica Chimica Acta 361 (2008) 1744–1753
1753
(f) G. Albertin, S. Antoniutti, F. Bredariol, J. Organomet. Chem. 679
(2003) 208;
(g) G. Albertin, S. Antoniutti, A. Bacchi, B. Fregolent, G. Pelizzi,
Eur. J. Inorg. Chem. (2004) 1922.
[10] (a) W.G. Peet, D.H. Gerlach, Inorg. Synth. 15 (1974) 38;
(b) D.H. Gerlach, W.G. Peet, E.L. Muetterties, J. Am. Chem. Soc. 94
(1972) 4545.
[11] Hydride-triflate
MHðj1-OTfÞP4
complexes
½M@Ru,Os;P@
[4] (a) G. Albertin, S. Antoniutti, M. Lanfranchi, G. Pelizzi, E.
Bordignon, Inorg. Chem. 25 (1986) 950;
PðOEtÞ3ꢁ were prepared by reacting dihydride MH2P4 with
equimolar amounts of either triflic aciþd (Ru) or methyltriflate
MeOTf (Os). j2-Triflate ½Mðj2-OTfÞP4ꢁ cations were obtained
by treating MHðj1-OTfÞP4 with an equimolar amount of triflic
acid. See: (a) G. Albertin, S. Antoniutti, A. Bacchi, E.
Bordignon, P.M. Dolcetti, G. Pelizzi, J. Chem. Soc., Dalton
Trans. (1997) 4435;
(b) G. Albertin, S. Antoniutti, G. Pelizzi, F. Vitali, E. Bordignon, J.
Am. Chem. Soc. 108 (1986) 6627;
(c) G. Albertin, S. Antoniutti, G. Pelizzi, F. Vitali, E. Bordignon,
Inorg. Chem. 27 (1988) 829;
(d) G. Albertin, S. Antoniutti, E. Bordignon, J. Chem. Soc., Dalton
Trans. (1989) 2353;
(e) G. Albertin, S. Antoniutti, A. Bacchi, D. Barbera, E. Bordignon,
G. Pelizzi, P. Ugo, Inorg. Chem. 37 (1998) 5602;
(f) G. Albertin, S. Antoniutti, M. Boato, Inorg. Chim. Acta 357
(2004) 1119.
(b) G. Albertin, S. Antoniutti, A. Bacchi, M. Bergamo, E.
Bordignon, G. Pelizzi, Inorg. Chem. 37 (1998) 479.
[12] PbðOAcÞ4 is often used as an oxidant in coordination chemistry,
and its ability to oxidize coordinate hydrazine to diazene
selectively is largely documented. See: (a) G. Albertin, S.
´
´
[5] (a) G. Albertin, S. Antoniutti, E. Bordignon, F. Menegazzo, J.
Chem. Soc., Dalton Trans. (2000) 1181;
Antoniutti, M. Bortoluzzi, J. Castro-Fojo, S. Garcıa-Fontan,
Inorg. Chem. 43 (2004) 4511;
(b) G. Albertin, S. Antoniutti, E. Bordignon, A. Tasin, J. Organomet.
Chem. 627 (2001) 99.
[6] R. Rabinowitz, J. Pellon, J. Org. Chem. 26 (1961) 4623.
[7] G. Balacco, J. Chem. Inf. Comput. Sci. 34 (1994) 1235.
[8] G. Albertin, S. Antoniutti, M. Bettiol, E. Bordignon, F. Busatto,
Organometallics 16 (1997) 4959.
(b) D. Sutton, Chem. Rev. 93 (1993) 995;
(c) G. Albertin, S. Antoniutti, A. Bacchi, F. De Marchi, G.
Pelizzi, Inorg. Chem. 44 (2005) 8947, and references therein.
[13] W.J. Geary, Coord. Chem. Rev. 7 (1971) 81.
[14] D.M. Adams, Metal–Ligand and Related Vibrations, St. Martin’s
Press, New York, 1968.
´
´
[9] G. Albertin, S. Antoniutti, S. Garcıa-Fontan, R. Carballo, F.
[15] G. Albertin, S. Antoniutti, A. Bacchi, E. Bordignon, M.T. Giorgi,
G. Pelizzi, Angew. Chem., Int. Ed. 41 (2002) 2192.
Padoan, J. Chem. Soc., Dalton Trans. (1998) 2071.