Synthesis and reactivity of diphosphine metal complexes bearing peripheral ketenimine functionalities

Article abstract of DOI:10.1039/b903375k

Diphosphinoketenimine ligands (PPh₂)₂CCNR (1a R = ^tBu, 1b R = Ph) were reacted with different Cu(I), Ag(I), Au(I), Pd(II), Ru(II) and Mo(0) metal complexes bearing weakly coordinating ligands yielding a number of mono-, di-, and trimetallic species with the diphosphine acting as either chelate or bridging ligand. The reactivity of some of the new complexes toward water and MeLi was investigated. The mononuclear Pd(II) complex [PdCl₂{(PPh₂)₂CCNPh}] (6b) is transformed into the diphosphinoamide complex [PdCl₂{(PPh₂) ₂CHC(O)(NHPh)}] (12) by nucleophilic addition of water. Similarly, treatment of 6b with MeLi yields the diphosphinoenamine complex [PdCl ₂{(PPh₂)₂CC(Me)(NHPh)}] (14). A different behaviour is observed in the treatment of diphosphinoketenimine with water in the presence of Cu(I) ion, which leads to hydrolysis of the ligand involving P-C bond cleavage, underscoring the influence of the coordination environment in the reactivity showed by the coordinated ligand. The liberation of the metal assisted synthesized diphosphines from the Pd(II) metal center can be achieved easily and in quantitative yields by treatment with aqueous KCN solution.

Full text of DOI:10.1039/b903375k

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www.rsc.org/dalton | Dalton Transactions
Synthesis and reactivity of diphosphine metal complexes bearing peripheral
ketenimine functionalities†
Javier Ruiz,*a Marta P. Gonzalo,a Maril´ın Vivanco,a Roberto Quesadab and Marta E. G. Mosquerac
Received 18th February 2009, Accepted 11th September 2009
First published as an Advance Article on the web 2nd October 2009
DOI: 10.1039/b903375k
t
= =
Diphosphinoketenimine ligands (PPh2)2C C NR (1a R = Bu, 1b R = Ph) were reacted with different
Cu(I), Ag(I), Au(I), Pd(II), Ru(II) and Mo(0) metal complexes bearing weakly coordinating ligands
yielding a number of mono-, di-, and trimetallic species with the diphosphine acting as either chelate or
bridging ligand. The reactivity of some of the new complexes toward water and MeLi was investigated.
= =
The mononuclear Pd(II) complex [PdCl2{(PPh2)2C C NPh}] (6b) is transformed into the
=
diphosphinoamide complex [PdCl2{(PPh2)2CHC( O)(NHPh)}] (12) by nucleophilic addition of water.
Similarly, treatment of 6b with MeLi yields the diphosphinoenamine complex [PdCl2{(PPh2)2-
=
C C(Me)(NHPh)}] (14). A different behaviour is observed in the treatment of diphosphinoketexnimine
with water in the presence of Cu(I) ion, which leads to hydrolysis of the ligand involving P–C bond
cleavage, underscoring the influence of the coordination environment in the reactivity showed by the
coordinated ligand. The liberation of the metal assisted synthesized diphosphines from the Pd(II) metal
center can be achieved easily and in quantitative yields by treatment with aqueous KCN solution.
imidazoline, oxazoline, and quinoline functionalized diphosphine
Introduction
ligands, respectively. We have also succeeded in obtaining the
diphosphinoketenimine as free ligands by photochemical degra-
dation of the metal complexes,7 and shown their unique reactivity
in cycloaddition reactions with alkynes and heterocumulenes.9
On the other hand, apart from the above mentioned parent
Development of new ligands for their use in homogeneous catalysis
is an area of intense research, and functionalized phosphines,
especially those with nitrogen-containing functional groups, have
found increasing applications in this field.1 Indeed, functionalized
diphosphines have been shown to improve the selectivity of some
catalytic processes.2 The presence of additional functional groups
in the diphosphine provides interesting properties to these ligands
such as water solubility3 or the ability for anchoring to solid
matrices.4 Additionally, the new donor atoms in the functional
groups enhance the coordination versatility of these ligands.5
We have extensively studied the usefulness of simple
bis(diphenylphosphino)methane complexes in the synthesis of
functionalized diphosphine ligands.6 In this regard, we have
reported the formation of diphosphinoketenimines of formula
= =
complex fac-[MnI(CO)3{(PPh2)2C C NR}] the coordination
chemistry of the new diphosphinoketenimine ligands remains
unexplored. It is expected that the reactivity of the ketenimine
fragment may be modulated by coordination to different metals.
In this paper we describe the synthesis of different copper(I), sil-
ver(I), gold(I), palladium(II), ruthenium(II) and molybdenum(0)
complexes containing diphosphinoketenimines ligands, defining
mono-, di- and trimetallic cores surrounded by organic peripheral
functionalities. The results show that the new complexes are
structurally comparable to those of the parent ligand dppm,
but present notable differences arising from the electronic and
structural singularities of the diphosphinoketenimine ligand, as
well as from the possibility of the ketenimine residue to undergo
further transformations on coordination. The reactivity of the
ketenimine moiety is dependent on the coordination environment
and some of the new functionalized ligands synthesized can be lib-
erated from the metal center effectively when using palladium(II)
complexes.
(PPh2)2C C NR (R = tBu, Ph) coordinated in the Mn(I)
= =
= =
complex fac-[MnI(CO)3{(PPh2)2C C NR}] via metal-assisted
coupling of a transient diphosphinocarbene and isocyanides.7 The
ketenimine moiety of the new coordinated diphosphines display a
rich reactivity, which further increases the synthetic potential of
these ligands for the generation of sophisticated diphosphines. Re-
action with isocyanides,7 and nucleophilic additions of propargylic
amines and alcohols,8a or Grignard reagents8b allow the controlled
transformation of the diphosphinoketenimine, affording indole,
Results and discussion
aDepartamento de Qu´ımica Orga´nica e Inorga´nica, Facultad de Qu´ımica,
Universidad de Oviedo, 33071, Oviedo, Spain. E-mail: jruiz@uniovi.es;
Fax: (+34) 985103446
Complexes of group 11 metals
bDepartamento de Qu´ımica, Facultad de Ciencias, Universidad de Burgos,
09001, Burgos, Spain
The treatment of [Cu(NCMe)4]BF4, AgClO4 or [AuCl(THT)]
(THT = tetrahydrothiophene) with stoichiometric amounts of
cDepartamento de Qu´ımica Inorga´nica, Universidad de Alcala´, 28871, Alcala´
de Henares, Spain
† CCDC reference numbers 720842–720844 for compounds 3a, 5b and
11. For crystallographic data in CIF or other electronic format see DOI:
10.1039/b903375k
t
= =
(PPh2)2C C NR (1a R = Bu, 1b R = Ph) readily affords the
= =
dinuclear diphosphine complexes [Cu2{(Ph2P)2C C NR}2-
= =
(2a-b), [Ag2(OClO3)2{(Ph2P)2C C NR}2]
(NCMe)2][BF4]2
= =
(3a-b), and [Au2{(Ph2P)2C C NR}2][Cl]2 (4a-b), respectively
9280 | Dalton Trans., 2009, 9280–9290
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in high yield (Scheme 1). The use of the coordinatively
unsaturated metallic fragment (AgClO4) or the presence of
weakly coordinating ligands such as acetonitrile or THT, allows
the reaction to take place under very mild conditions (5–15 min
of stirring at room temperature). The new compounds were
characterized spectroscopically, by elemental analysis, and single
crystal X-ray diffraction (in the case of 3a). The frequency of
more apparent in the case of 1a, as a result of the stabilization of
the zwitterionic form of the ketenimine group (form b) Scheme 2).
These data suggest that the peripheral ketenimine functionalities
become activated toward further reactivity compared to the free
1
ligand. As expected, the 31P{ H} NMR spectra show signals at
higher chemical shifts than those of the free ligand (Table 1).
For 2a-b and 4a-b singlet signals were observed corresponding to
the two equivalent phosphorus atoms; however the spectra of 3a
displays a complex multiplet signal arising from the coupling of
the phosphorus atoms with the silver nuclei in the three possible
combinations of isotopes 107Ag (I = 1/2; natural abundance
51.82%) and 109Ag (I = 1/2; natural abundance 48.18%). By
= =
the n(C C N) band in the free diphosphinoketenimine ligand
(2030 and 2002 cm-1 for 1a and 1997 cm-1 for 1b) undergoes an
appreciable increase upon coordination (between 15 and 66 cm-1),
1
contrast, the 31P{ H} NMR spectrum of 3b consists of a broad
singlet, indicating dissociation of the diphosphine ligand in
solution,10 which can be due to the lower donor ability of the
N-aryl ketenimine compared to the N-alkyl one. Coordination of
two acetonitrile molecules in complexes 2a and 2b is evidenced by
the presence of singlet signals for the methyl groups at 1.85 and
1
2.13 ppm, respectively, in the H NMR spectra. For complexes
4a-b, conductivity measurements indicate that the chloride anions
Scheme 1 Synthesis of dinuclear compounds 2–4a-b (a: R = tBu,
b: R = Ph).
Scheme 2 Possible resonance forms of the coordinated diphosphi-
noketenimine ligands
Table 1 Selected spectroscopic data for compounds 1–17
1
Compound IRa cm-1
31P{ H} NMR: d (ppm)b
1H NMR: d (ppm)a
1a
1b
2a
2b
3a
3b
4a
4b
5a
5b
6a
6b
7a
7b
8a
2030 (m), 2002 (s)
1997 (s)
2064 (s), 2022 (m)
2012 (s)
2067 (s)
2017 (s)
2071 (s)
2034 (s)
2051 (s)
2018 (s)
-10.5
-9.8
4.3 (s)
01.85 (s, 6 H, NCCH3)
2.13 (s, 6 H, NCCH3)
4.8 (s)c
20.6 (m)c
23.0 (br)c
37.4 (s)
38.7 (s)
0.7 (m)c
2.4 (m)c
2078 (s), 2054 (m)
2042 (s)
-36.7 (s)
-33.6 (s)e
2069 (m), 2046 (s)d
2023 (m), 2009 (s)d
9.4 (s, PPh2), -143.2 (hp, 1JPF = 711 Hz, PF6)d
13.3 (s, PPh2), -143.6 (hp, 1JPF = 711 Hz, PF6)d
2045 (w), 2023 (w)f n(CO) 1928 (s), 1833 (m), 13.4 (s)
1.01 (s, 3 H, CH3), 0.77 (s, 9 H, C(CH3)3),
1815 (m)f
9a
9b
11
12
13
2068 (s)
2036 (s)
34.1 (s)
35.2 (s)c
g
g
=
=
=
g
n(C
C
N) 2102 (s); n(P O) 1177 (s)
d 0.91 (br, 18 H, C(CH3)3)
-43.1 (s)e
4.69 (br, 1H, P2CH), 6.12 (s, 1H, NH)e
0.83 (s, 18 H, 2 C(CH3)3), 1.12 (s, 9 H,
C(CH3)3), 3.50 (d, 2 H, 2JHP = 8 Hz, CH2),
7.82 (s, 1H, NH)
=
n(N–H) 3406, n(C O) 1629
-14.4 (q, 2JPP = 51 Hz, 1 P), 7.6 (d,2JPP
=
=
=
=
n(N–H) 3335, n(C
C
N) 2074, n(C O)
1615g
51 Hz, 4 P)
14
n(N–H) 3347g
2050 (s)d
-38.9 (d), -31.1 6 (d),2JPP = 22 Hze
1.81 (s, 3H, CH3)e
15a
15b
16
45.5 (s)
47.1 (s)
-11.6 (s)
0.32 (t, 6 H, 3JHP = 4 Hz, AuCH3),
0.41 (t, 6 H, 3JHP = 4 Hz, AuCH3)
4.21 (br, 1 H, P2CH)
2027 (s)d
n(N–H) 3374
=
n(C O) 1660
17
n(N–H) 3366
-21.1 (d), -0.6 (d), 2JPP = 7 Hz
a
N) unless otherwise stated; b CD2Cl2; c D2O capillary/CH2Cl2; d THF; e CHCl3; f MeCN; g nujol.
=
=
CH2Cl2, n(C
C
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◦
˚
in the presence of NaI, cationic trinuclear silver(I) complexes
Table 2 Selected bond lengths (A) and angles ( ) for compound 3a
= =
of formula [Ag3I2{(PPh2)2C C NR}3]I (5a–b) were obtained
Ag(1)–Ag(2)
Ag(1)–O(1)
P(2)–Ag(1)
P(1)–Ag(1)
C(1)–C(2)
C(2)–N(1)
P(1)–C(1)
3.0170(11)
2.559(5)
2.447(2)
2.440(2)
1.328(11)
1.195(10)
1.806(7)
P(1)–Ag(1)–P(2)
P(1)–Ag(1)–O(1)
P(2)–Ag(1)–O(1)
O(1)–Ag(1)–Ag(2)
P(1)–Ag(1)–Ag(2)
P(2)–Ag(1)–Ag(2)
P(1)–C(1)–P(3)
151.25(7)
115.67(16)
93.06(16)
97.60(14)
93.95(5)
82.60(5)
119.2(4)
133.0(7)
(Scheme 3).
C(2)–N(1)–C(4)
are dissociated in solution, though weak Au ◊ ◊ ◊ Cl contacts could
exist in the solid state.11
Complex 3a was further characterized by X-ray diffraction.
Colorless single crystals suitable for an X-ray analysis were
obtained by slow diffusion of hexane into a dichloromethane
solution of the complex. A view of the structure is shown in
Fig. 1, and a selection of bond distances and angles is included in
Table 2. As the analogous dppm derivative [Ag2(OClO3)2(dppm)2]
(3a¢),12 3a is centrosymmetric, with the inversion center located
in the middle of the Ag–Ag segment. However other structural
features of 3a are different from those of the dppm complex.
Scheme 3 Synthesis of trinuclear silver (I) cluster 5a-b (a: R = tBu,
b: R = Ph).
This type of [Ag3X2(PP)3]X clusters is well known when PP
is a simple diphosphine ligand and X an anion such as halides,
pseudohalides or acetylides.13 The IR spectra of these compounds
= =
show an increase of the frequency of the n(C C N) band,
˚
similarly to that discussed in the case of the dinuclear derivatives
Thus, the Ag–O distance is much shorter in 3a (2.559(5) A)
1
2–4 (Table 1). The 31P{ H} NMR spectra displayed a complex
˚
than in 3a¢ (2.878(9) A), implying a stronger interaction of the
signal centered at 0.6 and 2.4 ppm for 5a and 5b, respectively.
Conductivity experiments in acetone suggest a 1:1 electrolyte,
showing that the bridging iodide ligands do not dissociate in
solution. In order to obtain suitable crystals for X-ray analysis, the
perchlorate anion with the metal in the first case. The P–Ag–P
arrangement, which is almost linear in 3a¢ (173.49(3)◦) and other
similar diphosphine Ag(I) complexes, appears considerably bent in
3a (151.25(7)◦), so that the structure may no longer be viewed as an
elongated chair form of an eight-membered ring. The coordination
geometry around the silver atoms in 3a can be considered as very
distorted trigonal or almost T-shaped, and is completed with a
-
external iodide anion in 5b was replaced by ClO4 , by treatment of
this compound with AgClO4. The structure of the complex cation
of 5b-ClO4 (Fig. 2) is very similar to that of [Ag3I2(dppm)3]+(5b¢),12c
featuring a trigonal bipyramidal Ag3I2 core and three bridging
diphosphine ligands defining an almost planar Ag3P6 skeleton,
but additionally containing three peripheral ketenimine groups,
two of them being slightly laid out toward one side of that Ag3P6
plane and the remaining one toward the opposite side. The Ag–Ag
˚
silver–silver contact of 3.017 A, which is slightly longer than that
˚
found in 3a¢. The Ag–P bond lengths in 3a (mean value 2.44 A)
˚
are similar to those displayed by 3a¢ (mean value 2.40 A), and the
P–C–P angle in 3a (119.2(4)◦) is in the expected range considering
the sp2 hybridization of the carbon atom, being clearly larger than
that found in 3a¢ (111.36(9)◦). It should be noted that conductivity
experiments carried out on dichloromethane solutions show that
3a behaves as a 1:2 electrolyte, indicating that the perchlorate anion
is dissociated from the metal center in solution.
˚
distances (average 3.135 A) are slightly shorter than those in 5b¢
˚
(average 3.236 A) (Table 3). The Ag–P and Ag–I distances in 5b
˚
(2.47 and 2.95 A, respectively) are almost identical to those found
˚
in 5b¢ (2.47 and 2.97 A, respectively), and the P–C–P angle in 5b
is 114◦.
Fig. 1 Crystal structure of complex 3a (thermal ellipsoids at 30%
probability level) with the atomic numbering scheme. Phenyl groups
omitted for clarity.
Fig. 2 Crystal structure of cation complex 5b with atomic numbering
scheme (thermal ellipsoids at 30% probability level). For clarity, phenyl
groups have been omitted.
When the reaction of AgClO4 with a stoichiometric amount
t
= =
of (PPh2)2C C NR (1a R = Bu, 1b R = Ph) was carried out
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◦
˚
Attempts to coordinate the ketenimine residue
Table 3 Selected bond lengths (A) and angles ( ) for compound 5b
In all the examples discussed so far the coordination of the
diphosphinoketenimine occurs exclusively through the phospho-
rus atoms either as a bridging or chelating ligand. This prompted
us to explore the possibility of coordinating the ketenimine
group to metal centers.14 Treatment of the dinuclear gold(I)
complexes 4a-b with two equivalents of [AuCl(THT)] yielded
Ag(1)–Ag(2)
Ag(2)–Ag(3)
Ag(1)–Ag(3)
Ag(1)–I(1)
Ag(2)–I(1)
Ag(3)–I(1)
P(1)–C(1)
P(2)–C(1)
C(1)–C(2)
C(2)–N(2)
3.0797(7)
3.2259(7)
3.1019(6)
2.9431(6)
3.0167(6)
2.9550(6)
1.821(7)
1.814(7)
1.332(9)
1.195(9)
Ag(2)–Ag(1)–Ag(3)
Ag(1)–Ag(2)–Ag(3)
Ag(1)–Ag(3)–Ag(2)
I(2)–Ag(2)–I(1)
P(3)–Ag(1)–Ag(2)
P(1)–Ag(2)–Ag(3)
P(5)–Ag(3)–Ag(1)
P(1)–C(1)–P(2)
62.912(15)
58.881(15)
58.208(15)
103.863(19)
151.14(4)
145.96(4)
145.87(4)
117.2(3)
= =
the neutral dinuclear complexes [Au2(Cl)2{(Ph2P)2C C NR}]
C(24)–N(2)–C(2)
131.3(7)
(9a-b) in which the diphosphinoketenimine is bridging two AuCl
fragments (Scheme 5), instead of the target coordination of
the new Au(I) fragment through the ketenimine residue. This
compound can also be prepared by direct treatment of 1a-b with
Mononuclear Pd(II), Ru(II) and Mo(0) complexes
two equivalents of [AuCl(THT)]. Reaction of the parent diphos-
We decided to prepare mononuclear complexes with chelating
diphosphino ligands, more similar to our previously reported man-
ganese(I) complexes.7 Following conventional procedures for the
synthesis of diphosphine complexes we reacted [PdCl2(NCMe)2],
[{Ru(p-cymene)(m-Cl)Cl}2] and fac-[Mo(CO)3(NCMe)3] with
t
= =
phinoketenimine complex fac-[MnI(CO)3{(PPh2)2C C N Bu}]
with metallic fragments containing labile ligands such as the above
[AuCl(THT)] or [PdCl2(NCMe)2] also led to transmetalation
of the diphosphine ligand giving 9a and 6a, respectively. A
different strategy would be to use the oxidized form of the
= =
1a-b to readily obtain [PdCl2{(PPh2)2C C NR}] (6a-b), [{Ru(p-
t
15
=
= =
diphosphinoketenimine {(O PPh2)2C C N Bu} (10).
= =
cymene)Cl{(PPh2)2C C NR}]PF6 (7a-b) and fac-[Mo(CO)3-
t
= =
(NCMe){(PPh2)2C C N Bu}] (8) respectively in very high yields
(Scheme 4). All the compounds were characterized spectroscop-
ically and by elemental analysis (Table 1). The treatment of
the dinuclear ruthenium complex with 1a-b is carried out in
the presence of TlPF6 as halide extractor in order to facilitate
the reaction. If the reaction is carried out in the absence of
TlPF6, an intermediate complex is spectroscopically detected,
corresponding to a neutral derivative in which the diphosphine is
coordinated in a monodentate fashion [{Ru(p-cymene)(Cl)2{h1-
t
31
1
= =
(PPh2)2C C N Bu}] ( P{ H} NMR spectra shows two doublets
2
at d -11.8 and 28.7, JPP = 73 Hz). This compound slowly
t
= =
evolved to [{Ru(p-cymene)Cl{(PPh2)2C C N Bu}]Cl (7a-I) by
t
Scheme 5 Synthesis of gold(I) complexes 9a-b (a: R = Bu, b: R = Ph).
displacement of one of the chloride ligands from the coordi-
nation sphere by the free phosphorus atom albeit in a lower
yield.
=
The donor nature of the O P groups does not favor the
coordination with soft metal ions, thus coordination of the keten-
imine group may result. Surprisingly, reaction of [Cu(NCMe)4]BF4
with 10 yielded a green solution which displayed no signals
1
in the 31P{ H} NMR spectrum, suggesting the presence of a
paramagnetic Cu(II) complex. From this solution, the com-
t
=
= =
plex [Cu{(Ph2P O)2C C N Bu}2(BF4)][BF4] (11) was isolated
(Scheme 6). Disproportionation of Cu(I) to Cu(II) and Cu(0)
=
seems to be favored by the coordination of the P O group. The
-1
= =
frequency of the n(C C N) band in the IR spectra (2102 cm )
indicates the non-participation of this group in the coordination
to the metal center. The structure of the complex 11 was elucidated
by X-ray diffraction (Fig. 3). The metal center is found in a
square pyramid coordination environment, interacting with two
dioxidized diphosphinoketenimine ligands and a fluorine atom of
the tetrafluoroborate group in an apical position. Cu–O distances
˚
are 1.927(2)–1.950(2) A, similar to other copper(II) complexes
Scheme 4 Synthesis of mononuclear complexes 6a-b, 7a-b and 8 (a: R =
tBu, b: R = Ph).
The molybdenum compound 8 is not stable in solution
and decomposes to the corresponding tetracarbonyl derivative
t
= =
[Mo(CO)4{(PPh2)2C C N Bu}] (8-I). This compound is also
quantitatively obtained by treatment of 8 with CO.
Scheme 6 Synthesis of Cu(II) derivative 11.
Dalton Trans., 2009, 9280–9290 | 9283
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˚
complex [PdCl2{(PPh2)2CHC(=O)(NHPh)}] (12) as a result of
Table 4 Selected bond lengths (A) and angles ( ) for compound 11
=
the nucleophilic addition of H2O to the C N ketenimine double
Cu(1)–O(2)
Cu(1)–O(1)
Cu(1)–O(4)
Cu(1)–O(3)
Cu(1)–F(11)
C(3)–N(3)
C(4)–N(4)
C(1)–C(3)
C(2)–C(4)
P(1)–C(1)
1.928(2)
1.935(2)
1.938(2)
1.951(2)
2.2719(19)
1.175(4)
1.177(4)
1.346(4)
1.343(4)
1.774(3)
1.765(3)
P(2)–C(2)
P(4)–C(2)
1.775(3)
1.772(3)
92.46(9)
174.64(10)
166.42(9)
92.91(9)
147.2(3)
143.5(3)
bond (Scheme 7). Presumably the reaction takes place through an
enol intermediate, which spontaneously tautomerizes giving the
observed product. The spectroscopic data of this compound are
in agreement with this proposed formulation. The IR spectrum
O(1)–Cu(1)–O(3)
O(1)–Cu(1)–O(4)
O(2)–Cu(1)–O(3)
O(2)–Cu(1)–O(4)
C(3)–N(3)–C(30)
C(4)–N(4)–C(40)
P(1)–C(1)–P(3)
P(2)–C(2)–P(4)
displays bands at 1629 cm-1 and 3406 cm-1 assignable to the C O
=
and N–H stretchings respectively. The 1H NMR spectrum showed
signals corresponding to the N–H and P2C–H groups and the
119.36(17)
118.08(16)
1
31P{ H} NMR spectrum displayed one signal corresponding to the
P(3)–C(1)
two equivalent phosphorus atoms (Table 1). No reaction occurred
in the treatment of 6a with water showing the minor ability of
N-alkyl diphosphinoketenimine to undergo nucleophilic addition
compared to the N-aryl ones.
Group 11 dimetallic compounds of the type 2, 3 and 4 did
not react with water under these conditions, which reflect the
distinct reactivity of the ligand depending on the metal complex
examined. In this case we observed the hydrolysis of the tert-butyl
diphosphinoketenimine 1a when an excess of the diphosphine
is reacted with [Cu(NCMe)4]BF4. Under these conditions a
new derivative 13 was obtained (Scheme 7). This compound
displays a bridging phosphinoamide ligand in addition to two
diphosphinoketenimine ligands. The new ligand appears to be
the result of the hydrolysis of a diphosphinoketenimine ligand
by two molecules of water, involving P–C bond cleavage.18 This
mechanism is also supported by the formation of a stoichiometric
1
amount of O PHPh2 (singlet signal at 22.4 ppm in the 31P{ H}
Fig. 3 Crystal structure of cation complex 11 with atomic numbering
scheme (thermal ellipsoids at 30% probability level).
=
NMR spectrum) together with 13. In fact, the 1:1 adduct of 13 with
=
O PHPh2 (compound 13-I) can also be obtained by quick crys-
with O-donor ligands.15 The copper site is displaced slightly
above the plane containing the four oxygen atoms and the Cu–F
tallization from the reaction mixture (see Experimental section).
During the reaction, the immediate formation of 2a was observed,
followed soon afterwards by an intermediate which only displays
˚
distance of 2.272(2) A is short compared to other complexes
-
with coordinated BF4 indicating a strong interaction with the
one signal at 13 ppm in the 31P{ H} NMR spectrum was detected,
1
metal center.16,17 The structural parameters of the ketenimine
fragment are in agreement with an important contribution of
a charge-separated form of the ligand (form b) in scheme 1),
being likely a dinuclear copper complex with three coordinated
diphosphinoketenimine ligands.19 This compound spontaneously
=
evolved to give O PHPh2 and 13. The spectroscopic data of 13
are in agreement with the proposed formulation (Table 1). The IR
spectrum showed signals corresponding to the C O (1615 cm )
which is also in consonance with the high frequency of the
-1
= =
n(C C N) band (2102 cm ) found in the IR spectrum of this
-1
=
˚
complex. Thus, C3–N3 and C4–N4 bond distances, 1.173(5) A and
and N–H (3335 cm-1) stretching bands respectively. The 1H NMR
spectrum showed signals corresponding to two different tert-butyl
groups in a 2:1 ratio, along with a doublet corresponding to the
CH2 group and a broad singlet at 7.82 ppm assignable to the
˚
1.175(5) A respectively are shorter than a double bond, and the
bond angles C3–N3–C30 (147.3(4)◦) and C4–N4–C40 (143.6(4)◦)
are significantly wider than 120o (Table 4).
N–H residue. The 31P{ H} NMR spectra displayed two signals as
1
Reactivity of coordinated diphosphinoketenimine ligands
a quintuplet and doublet corresponding to the phosphinoamide
and diphosphinoketenimine ligands respectively. The equivalence
of the diphosphinoketenimine phosphorus atoms suggest the
existence of a fluxional process interconverting the positions of
the phosphinoamide ligand.20 At low temperature (-60 ◦C) the
We set out to study the reactivity of the coordinated
diphosphinoketenimine ligands with nucleophiles such as water
and MeLi. We have previously examined the reactivity of the
= =
carbonyl Mn(I) complex fac-[MnI(CO)3{(PPh2)2C C NPh}]
31P{ H} NMR spectra of this compound showed a triplet signal for
1
with these reagents, and found no reaction with water and
formation of a diphosphinoenamine ligand on treatment with
MeLi.8b Liberation of the diphosphinoenamine ligand from the
metal center proved to be difficult and only moderate to low
yields could be obtained after photodegradation of the complex.
In this regard, we envisioned that palladium(II) complexes would
be more appropriate in order to enhance the reactivity of the
ketenimine functionality and to achieve the demetalation of the
newly obtained diphosphine ligands.
the phosphinoamide ligand, suggesting that this fluxional process
is frozen, although the signal corresponding to the phosphorus
atoms of the diphosphinoketenimine ligands appeared as a poorly
resolved multiplet. A preliminary X-ray diffraction study for 13-I
was carried out confirming the proposed structure for this complex
(Fig. 4).21,22
= =
Treatment of [PdCl2{(PPh2)2C C NPh}] (6b) with one equiva-
lent of MeLi in THF at -78 ◦C resulted in the diphosphinoenamine
= =
=
The reaction of [PdCl2{(PPh2)2C C NPh}] (6b) with an
complex [PdCl2{(PPh2)2C C(Me)(NHPh)}] (14) after hydrolysis
excess of distilled water in THF led to the diphosphinoamide
of the anionic intermediate obtained by nucleophilic addition of
9284 | Dalton Trans., 2009, 9280–9290
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Scheme 7 Reactivity of diphosphinoketenimine complexes with H2O.
the carbanion (Scheme 8). The enamine form of the ligand is sup-
ported by the spectroscopic data of the compound (Table 1). Thus,
1
the 31P{ H} NMR spectrum displayed two signals corresponding
to the inequivalent phosphorus atoms and the IR spectrum showed
a band at 3347 cm-1 assignable to the N–H stretching.
Similar to the results obtained in the reaction with water,
the dinuclear complexes 2–4a-b did not undergo nucleophilic
attack by MeLi under these conditions. On the other hand,
= =
the neutral gold(I) complexes [Au2(Cl)2{(Ph2P)2C C NPR}]
(9a-b), reacted with MeLi to give the substitution products
= =
[Au2(Me)2{(Ph2P)2C C NPR}] (15a-b), as a result of the replace-
ment of the chloride ligands by methyl groups (Scheme 8), instead
of nucleophilic addition to the ketenimine functionality.
Liberation of the diphosphines
Another target we wanted to address with this work was to develop
an efficient method to liberate the functionalized diphosphines
from the metal centers in a simple high yielding procedure. So
far, our efforts involving ligands coordinated to manganese(I)
complexes resulted in low yields of the free ligands.8b In this
regard, the demetalation of diphosphine ligands coordinated to
Pd(II) complexes by treatment with aqueous solutions of KCN
has been reported.23 We adapted this method to our system, and
treatment of solutions of 12 or 14 in dichloromethane with a small
Fig. 4 Molecular structure of cation complex 13-I with atomic numbering
scheme. For clarity, only the ipso carbons of the diphosphinoketenimine
groups are shown.
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t
Scheme 8 Reactivity of diphosphinoketenimine complexes 6b and 9a-b (a: R = Bu, b: R = Ph) with MeLi.
volume of an aqueous solution KCN with vigorous stirring yielded
Experimental
=
quantitatively free diphosphinoamide (PPh2)2CHC( O)(NHPh)
General
=
(16) and diphosphinoenamine (PPh2)2C C(CH3)(NHPh) (17)
ligands, respectively (Schemes 7 and 8), which are purified
by simple filtration over diatomaceous earth (see Table 1 and
the Experimental section for the spectroscopic data of these
compounds). This result bodes well for use of this type of
complex in the metal-mediated synthesis of more sophisticated
diphosphines.
All reactions and manipulations were performed under an
atmosphere of dry nitrogen by standard Schlenk techniques.
Solvents were distilled over appropriate drying agents under dry
nitrogen before use. The IR spectra were measured with Perkin-
Elmer FT 1720-X and Paragon 1000 spectrophotometers. The
C, H, and N analyses were performed on a Perkin-Elmer 240B
elemental analyzer. NMR spectra were recorded on Bruker 300
and 400 MHz spectrometers. Coupling constants J are given in Hz.
Chemical shifts of the NMR spectra were referenced to internal
SiMe4 (1H and 13C) or external H3PO4 (31P). [Cu(NCMe)4]BF4,24
Conclusions
AuCl(THT),25 [PdCl2(NCMe)2],26 [{Ru(p-cymene)(m-Cl)Cl}2],27
We have synthesized different mononuclear complexes of Pd(II),
Ru(II) and Mo(0), and polynuclear complexes of Cu(I), Ag(I)
7
[Mo(CO)3(NCMe)3],28 [(PPh2)2C C NR], and [(O PPh2)2-
= =
= =
=
t
15
C C N Bu], were prepared as described elsewhere. All other
reagents were obtained commercially and used without further
purification.
= =
and Au(I) bearing the diphosphinoketenimines (PPh2)2C C NR
(1a R = tBu, 1b R = Ph) acting as either chelating or
bridging ligands, respectively. The peripheral ketenimine func-
tionalities in these complexes show no tendency to coordi-
nate to other metallic fragments, and its reactivity in nucle-
ophilic addition processes depends on the coordination envi-
ronment of the diphosphine. Thus, reaction of the mononu-
Safety note: Perchlorate salts of metal complexes with organic
ligands are potentially explosive. Only small amounts of such
materials should be prepared, and these should be handled with
great caution.
= =
clear complex [PdCl2{(PPh2)2C C NPh}] (6b) with water
=
and MeLi affords [PdCl2{(PPh2)2CHC( O)(NHPh)}] (12) and
Syntheses
=
[PdCl2{(PPh2)2C C(Me)(NHPh)}] (14), respectively, whereas no
t
= =
reaction occurred when using group 11 dinuclear complexes,
except in the treatment of a Cu(I) derivative with water which
leads to the hydrolysis of the diphosphine involving P–C bond
cleavage. The new functionalized diphosphines of complexes 12
and 14 can be liberated from the Pd(II) center in quantitative
yield using a straightforward procedure. It is expected that this
result will allow the metal mediated synthesis of more sophisticated
diphosphines, including asymmetric ones, by reaction with amines
and alcohols. Work along these lines is currently in progress in our
group.
[Cu2{(Ph2P)2C C N Bu}2(NCMe)2][BF4]2 (2a). To a solu-
t
= =
tion of (Ph2P)2C C N Bu 1a (50 mg, 0.11 mmol) in 20 mL
of CH2Cl2 was added [Cu(NCMe)4]BF4 (34 mg, 0.11 mmol)
at room temperature with continuous stirring. The reaction
occurs instantaneously, then, the solution was concentrated to
4 mL. Addition of hexane (15 mL) gave a white solid. Yield:
67 mg (95%). Anal. Calcd for C64H64B2Cu2F8N4P4: C, 58.51; H,
4.91; N, 4.26. Found: C, 58.13; H, 5.03; N, 4.06. FTIR (CH2Cl2):
n(C C N) 2064 (s), 2022 (m) cm ; 31P{ H} NMR (CD2Cl2): d
-1
1
= =
4.3 (s); 1H NMR (CD2Cl2): d 0.73 (s, 18 H, C(CH3)3), 1.85 (s, 6 H,
9286 | Dalton Trans., 2009, 9280–9290
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1
t
NCCH3), 7.3–7.6 (m, 40 H, Ph); 13C{ H} NMR (D2O/CH2Cl2): d
[Ag3I2{(Ph2P)2C C N Bu}3]I (5a). To a mixture of NaI
= =
t
≡
= =
= =
2.1 (s, N C–CH3), 29.7 (s, C(CH3)3), 35.9 (br, P2C C N), 61.7
(s, C(CH3)3), 123.0 (s, N C–CH3), 148.3 (s, P2C C N).
(66 mg, 0.44 mmol) and (Ph2P)2C C N Bu 1a (50 mg, 0.11 mmol)
≡
= =
in THF/CH2Cl2 (20 mL/10 mL) was added solid AgClO4 (22 mg,
0.11 mmol) in the dark. The reaction mixture was stirred for 2 h,
the solution was then removed in vacuo and the crude product
was taken up in dichloromethane (15 mL) and filtered. The filtrate
was concentrated to 5 mL and 20 mL of hexane was then added
to produce a white solid. Yield: 65 mg (86%). Anal. Calcd for
C90H87Ag3I3N3P6: C, 51.45; H, 4.17; N, 2.00. Found: C, 51.69; H,
= =
[Cu2{(Ph2P)2C C NPh}2(MeCN)2][BF4]2 (2b). The proce-
dure is analogous to that described above, using [Cu(NCMe)4]BF4
= =
(32 mg, 0.10 mmol) and (Ph2P)2C C NPh 1b (50 mg, 0.10 mmol).
The product obtained is a white solid. Yield: 66 mg (95%).
Anal. Calcd for C68H56B2Cu2F8N4P4: C, 60.33; H, 4.17; N, 4.14.
= =
Found: C, 59.90; H, 4.28; N, 4.05. FTIR (CH2Cl2): n(C C N)
4.35; N, 1.96. FTIR (CH2Cl2): n(C C N) 2051 (s) cm ; 31P{ H}
-1
1
= =
2012 (s) cm-1; 31P{ H} NMR (D2O/CH2Cl2): d 4.8 (s); 1H NMR
1
NMR (D2O/CH2Cl2): d 0.7 (m); 1H NMR (CD2Cl2): d 0.61 (s, 27
(CD2Cl2): d 2.13 (s, 6 H, NCCH3), 6.5–7.7 (m, 50 H, Ph).
H, C(CH3)3), 7.1–7.6 (m, 60 H, Ph); 13C{ H} NMR (CD2Cl2): d
1
t
= =
30.1 (s, C(CH3)3), 41.9 (br, P2C C N), 60.6 (s, C(CH3)3), 154.7
= =
= =
(3a). (Ph2P)2C C
[Ag2(OClO3)2{(Ph2P)2C C N Bu}2]
(s, P2C=C=N); Conductivity (acetone, 20 ◦C): 118 S cm2 mol-1.
NtBu 1a (40 mg, 0.09 mmol) was dissolved in a mixture of THF
(10 mL) and CH2Cl2 (5 mL). AgClO4 (18 mg, 0.09 mmol) was
added to this solution in the dark and the resulting mixture was
vigorously stirred for 15 min. After this time, the solvent was
evaporated to dryness under reduced pressure. To the residue was
added CH2Cl2 (10 mL) and the resulting solution was filtered off
and concentrated to 5 mL. Addition of hexane (20 mL) gave a
white solid. Slow diffusion of hexane into a CH2Cl2 solution of the
compound afforded colourless crystals suitable for X-ray diffrac-
tion. Yield: 51 mg (89%). Anal. Calcd for C60H58Ag2Cl2N2O8P4:
C, 53.55; H, 4.34; N, 2.08. Found: C, 53.27; H, 4.21; N, 2.03.
= =
[Ag3I2{(Ph2P)2C C NPh}3]I (5b). The compound was pre-
pared following the same method described for 5a, with
= =
(Ph2P)2C C NPh (50 mg, 0.10 mmol) and AgClO4 (21 mg,
0.10 mmol). Yield: 61 mg (82%). Anal. Calcd for C96H75Ag3I3N3P6:
C, 53.36; H, 3.50; N, 1.94. Found: C, 53.25; H, 3.61; N,
2.01. FTIR (CH2Cl2): n(C C N) 2018 (s) cm ; 31P{ H} NMR
(D2O/CH2Cl2): d 2.4 (m);1H NMR (CD2Cl2): d 6.5–7.9 (m, 75
H, Ph); Conductivity (acetone, 20 ◦C): 126 S cm2 mol-1. In order
to obtain suitable crystals for X-ray analysis, the external iodide
-1
1
= =
-
anion in 5b was replaced by ClO4 as follows: To a solution of
FTIR (CH2Cl2): n(C C N) 2067 (s) cm ; 31P{ H} NMR
-1
1
= =
5b (104 mg, 0.048 mmol) in CH2Cl2 (20 mL) AgClO4 (10 mg,
0.048 mmol) was added in the dark. The mixture was stirred
for 30 min. The solution was then filtered off and concentrated
to 3 mL. Slow diffusion of hexane gave white crystals of
1
(D2O/CH2Cl2): d 20.6 (m); H NMR (CD2Cl2): d 0.72 (s, 18 H,
C(CH3)3), 7.3–7.6 (m, 40 H, Ph); 13C{ H} NMR (D2O/CH2Cl2):
1
d 29.9 (s, C(CH3)3), 62.1 (s, C(CH3)3), 148.1 (s, P2C=C=N).
Conductivity (dichloromethane, 20 ◦C): 46 S cm2 mol-1.
= =
[Ag3I2{(Ph2P)2C C NPh}3]ClO4 (5b-ClO4) Yield 83 mg (81%).
Anal. Calcd for C96H75Ag3ClI2N3O4P6: C, 54.05; H, 3.54; N, 1.97.
Found: C, 53.84; H, 3.41; N 1.85.
= =
[Ag2(OClO3)2{(Ph2P)2C C NPh}2] (3b). The procedure was
= =
similar to that for 3a except (Ph2P)2C C NPh 1b (40 mg,
t
t
0.08 mmol) and AgClO4 (17 mg, 0.08 mmol) were used instead
to give a white solid. Yield: 48 mg (85%). Anal. Calcd for
C64H50Ag2Cl2N2O8P4: C, 55.48; H, 3.64; N, 2.02. Found: C, 55.61;
= =
= =
[PdCl2{(PPh2)2C C N Bu}] (6a). (Ph2P)2C C N Bu 1a
(40 mg, 0.09 mmol) was added to a solution of [PdCl2(NCMe)2]
(22 mg, 0.09 mmol) in CH2Cl2 (10 mL) at room temperature with
continuous stirring. After 5 min, the solution turned dark yellow
and the solvent was removed in vacuo. The solid obtained was
washed with hexane (2 ¥ 5 mL) and dried, yielding a yellow solid.
Yield: 53 mg (97%). Anal. Calcd for C30H29Cl2NP2Pd: C, 56.05; H,
4.55; N, 2.18. Found: C, 55.83; H, 4.54; N, 2.15. FTIR (CH2Cl2):
n(C C N) 2078 (s), 2054 (m) cm ; 31P{ H} NMR (CD2Cl2): d
-36.7 (s); 1H NMR (CD2Cl2): d 1.05 (s, 9 H, C(CH3)3), 7.4–8.0 (m,
20 H, Ph).
-1
= =
H, 3.72; N, 1.96. FTIR (CH2Cl2): n(C C N) 2017 (s) cm ;
31P{ H} NMR (D2O/CH2Cl2): d 23.0 (m);1H NMR (CD2Cl2):
1
d 6.6–7.8 (m, 50 H, Ph); 13C{ H} NMR (CD2Cl2): d 44.0 (br,
1
= =
= =
P2C C N), 159.3 (s, P2C C N).
t
= =
[Au2{(Ph2P)2C C N Bu}2](Cl)2 (4a). AuCl(THT) (28 mg,
-1
1
= =
t
= =
0.08 mmol) was added to a solution of (Ph2P)2C C N Bu 1a
(40 mg, 0.08 mmol) in CH2Cl2 (15 mL) at room temperature
with continuous stirring. After 5 min, most of the solvent was
removed, and 20 mL of hexane was then added to produce a white
solid. Yield: 51 mg (92%). Anal. Calcd for C60H58Au2Cl2N2P4: C,
51.64; H, 4.19; N, 2.01. Found: C, 51.93; H, 4.19; N, 1.96. FTIR
= =
[PdCl2{(PPh2)2C C NPh}] (6b). The procedure was similar
= =
to that for 6a using (Ph2P)2C C NPh 1b (40 mg, 0.08 mmol) and
[PdCl2(NCMe)2] (21 mg, 0.08 mmol). Yield: 50 mg (94%). Anal.
Calcd for C32H25Cl2NP2Pd: C, 57.99; H, 3.80; N, 2.11. Found: C,
-1
1
(CH2Cl2): n(C C N) 2071 (s) cm ; 31P{ H} NMR (CD2Cl2):
= =
1
-1
d 37.4 (s); H NMR (CD2Cl2): d 0.69 (s, 18 H, C(CH3)3), 7.3–
= =
58.05; H, 3.94; N, 2.17. FTIR (CH2Cl2): n(C C N) 2042 (s) cm ;
8.0 (m, 40 H, Ph); 13C{ H} NMR (CD2Cl2): d 30.2 (s, C(CH3)3),
1
31P{ H} NMR (CDCl3): d -33.6 (s); 1H NMR (CD2Cl2): d 6.09–
1
13
1
= =
= =
43.4 (br, P2C C N), 62.6 (s, C(CH3)3), 151.1 (s, P2C C N);
= =
8.1 (m, 25 H, Ph); C{ H} NMR (CD2Cl2): 45.8 (br, P2C C N),
Conductivity (dichloromethane, 20 ◦C): 63 S cm2 mol-1.
=
151.5 (s, P2C C=N).
t
= =
= =
[Au2{(Ph2P)2C C NPh}2](Cl)2 (4b). This was prepared us-
[{Ru(p-cymene)Cl{(PPh2)2C C N Bu}]PF6 (7a). (Ph2P)2-
t
= =
= =
ing an identical procedure to 9a, starting from (Ph2P)2C C NPh
C C N Bu 1a (36 mg, 0.07 mmol) and TlPF6 (36 mg, 0.07 mmol)
2b (20 mg, 0.04 mmol) and AuCl(THT) (14 mg, 0.04 mmol). Yield:
25 mg (89%). Anal. Calcd for C64H50Au2Cl2N2P4: C, 53.54; H,
3.51; N, 1.95. Found: C, 53.87; H, 3.31; N, 2.04. FTIR (CH2Cl2):
were added to a solution of [{Ru(p-cymene)(m-Cl)Cl}2] (16 mg,
0.03 mmol) in THF (15 mL) at room temperature with continuous
stirring. After 20 min, the colour of the solution changed from
red to yellow. The solution was filtered under an inert atmosphere
and the filtrate was concentrated to 3 mL. 15 mL of hexane was
n(C C N) 2034 (s), cm ; 31P{ H} NMR (CD2Cl2): d 38.7 (s); 1H
-1
1
= =
NMR (CD2Cl2): d 6.4–7.9 (m, 50 H, Ph).
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then added to produce a yellow solid. Yield: 48 mg (91%). Anal.
Calcd for C40H43ClF6NP3Ru: C, 54.52; H, 4.92; N, 1.59. Found:
0.10 mmol), 32 mg of [Cu(NCMe)4]BF4 (0.10 mmol) were added.
The mixture was stirred at room temperature for 10 min giving
a clear green solution which was then filtered to remove a
small amount of Cu(0). Hexane (15 mL) was added and the
dichloromethane was removed by slow evaporation to give a
green precipitate. Suitable crystals of 5 for X-ray analysis were
obtained from a CH2Cl2/hexane solution. Yield: 52 mg (87%).
Anal. Calcd for C60H58B2CuF8N2O4P4: C, 58.49; H, 4.74; N, 2.27.
= =
C, 54.32; H, 4.92; N, 1.39. FTIR (THF): n(C C N) 2069 (m),
1
2046 (s), cm-1; 31P{ H} NMR (THF): d 9.4 (s, PPh2), -143.2 (hp,
1JPF = 711 Hz, PF6); H NMR (CD2Cl2): d 1.05 (d, 6 H, JHH
=
1
3
7, CH(CH3)2), 1.28 (s, 9H, C(CH3)3), 1.36 (s, 3H, CH3), 2.32 (hp,
1H, 3JHH = 7, CH(CH3)2), 5.61 (d, 2 H, 3JHH = 6, p-cymene), 5.88
(d, 2 H, 3JHH = 6, p-cymene), 7.3–7.7 (m, 20 H, Ph).
= =
Found: C, 58.41; H, 4.61; N, 2.22. FTIR (Nujol): n(C C N) 2102
(s), n(P O) 1177 (s) cm ; H NMR (CD2Cl2): d 0.91 (br, 18 H,
C(CH3)3), 7.2–9.1 (br, 40, Ph).
= =
[{Ru(p-cymene)Cl{(PPh2)2C C NPh}]PF6 (7b). The com-
-1
1
=
pound was prepared following the same method described
for 7a, with [{Ru(p-cymene)(m-Cl)Cl}2] (16 mg, 0.03 mmol),
=
[PdCl2{(PPh2)2CHC( O)(NHPh)}] (12). To a solution of 6b
= =
(Ph2P)2C C NPh 1b (30 mg, 0.06 mmol) and TlPF6
(40 mg, 0.06 mmol) in THF (10 mL) an excess of distilled water
(0.1 mL) was added and the mixture stirred vigorously for 1 h.
Over this time, a yellow precipitate appeared. The solvent was
then evaporated and the residue washed with diethyl ether (2 ¥
5 mL) to yield a yellow solid. Yield: 38 mg (93%). Anal. Calcd for
(36 mg, 0.07 mmol). Yield: 46 mg (86%). Anal. Calcd for
C42H39ClF6NP3Ru: C, 55.98; H, 4.36; N, 1.55. Found: C, 55.64; H,
-1
= =
4.42; N, 1.66. FTIR (THF): n(C C N) 2023 (m), 2009 (s), cm ;
31P{ H} NMR (THF): d 13.3 (s, PPh2), -143.6 (hp, 1JPF = 711 Hz,
1
1
3
PF6); H NMR (CD2Cl2): d 1.05 (d, 6 H, JHH = 7, CH(CH3)3),
1.38 (s, 3H, CH3), 2.31 (hp, 1H, 3JHH = 7, CH(CH3)2), 5.70 (d, 2
C32H27Cl2NOP2Pd: C, 56.45; H, 4.00; N, 2.06. Found: C, 56.86;
-1
3
3
=
H, 4.12; N, 2.00. FTIR (nujol): n(N–H) 3406, n(C O) 1629 cm ;
H, JHH = 6, p-cymene), 5.97 (d, 2 H, JHH = 6, p-cymene), 7.1-
31P{ H} NMR (CDCl3): d -43.1 (s); 1H NMR (CDCl3): d 4.69 (br,
1
7.8 (m, 25 H, Ph);13C{ H} NMR (CD2Cl2): 17.2 (s, CH3), 22.0(s,
1
1
1H, P2CH), 6.12 (s, 1H, NH) 6.7–8.1 (m, 25 H, Ph).
= =
CH(CH3)2), 31.0 (s, CH(CH3)2), 50.3 (t, JCP = 38, P2C C N),
68.1 (s, 2 ¥C p-cymene), 89.9 (s, 2 ¥ CH p-cymene), 91.2 (s, 2
t
t
= =
[Cu2 { (Ph2P)2 C C N Bu}2 {Ph2PCH2C (O) NH Bu} ] [BF4]2
2
¥CH p-cymene), 102.9 (s, 2 ¥C p-cymene), 150.5 (t, JCP = 8,
(13). To stirred dichloromethane (15 mL) solution of
a
P2C=C=N).
t
= =
(Ph2P)2C C N Bu (100 mg, 0.22 mmol) was added in one
portion solid [Cu(NCMe)4]BF4 (30 mg, 0.09 mmol) and
stirred for 20 min. Addition of hexane caused the forma-
tion of a very small amount of crystals corresponding to
t
= =
fac-[Mo(CO)3(NCMe){(PPh2)2C C N Bu}]
(8). (Ph2P)2-
t
= =
C C N Bu 1a (23 mg, 0.05 mmol) was added to a solution of
[Mo(CO)3(NCMe)3] (15 mg, 0.05 mmol) in acetonitrile (8 mL)
at room temperature with continuous stirring. After 5 min, the
solution was concentrated to 4 mL and 10 mL of hexane was
then added to produce a green-yellow solid. Yield: 34 mg (65%).
Anal. Calcd for C35H32MoN2O3P2: C, 61.23; H, 4.70; N, 4.08.
t
t
=
=
[Cu2{(Ph2P)2C
C
N Bu}2 {Ph2PCH2C(O)NH Bu}(OPHPh2)]-
[BF4]2 (13-I), as confirmed by X-ray diffraction. The mother
liquor was left to stand at -10 ◦C for two days, affording
colourless crystals of 13. Yield: 50 mg (52%). Anal. Calcd for
C78H80B2Cu2F8N3OP5: C, 61.19; H, 5.27; N, 2.74. Found: C, 60.87;
= =
Found: C, 60.75; H, 4.43; N, 3.91. FTIR (NCMe): n(C C N)
2045 (w), 2023 (w), n(CO) 1928 (s), 1833 (m), 1815 (m), cm-1;
= =
H, 5.39; N, 2.57. FTIR (Nujol): n(N–H) 3335, n(C C N) 2074,
-1
1
2
n(C O) 1615 cm ; 31P{ H} NMR (CD2Cl2): d -14.4 (q, JPP
=
1
=
31P{ H} NMR (CD2Cl2): d 13.4 (s); 1H NMR (CD2Cl2): d 1.01 (s,
51 Hz, 1 P), 7.6 (d,2JPP = 51 Hz, 4 P); 1H NMR (CD2Cl2): d 0.83
3 H, CH3), 0.77 (s, 9 H, C(CH3)3), 7.3–7.8 (m, 20 H, Ph).
(s, 18 H, 2 C(CH3)3), 1.12 (s, 9 H, C(CH3)3), 3.50 (d, 2 H, 2JHP
8 Hz, CH2), 6.5–7.5 (m, 50 H, Ph), 7.82 (s, 1H, NH).
=
t
= =
=
[Au2Cl2{(Ph2P)2C C N Bu}] (9a). A solution of (Ph2P)2C
t
=
C N Bu 1a (40 mg, 0.09 mmol) in CH2Cl2 (10 mL) was added
dropwise to a solution of AuCl(THT) (58 mg, 0.18 mmol) in
CH2Cl2 (5 mL) at room temperature with continuous stirring.
After 10 min, most of the solvent was removed, and 20 mL of
hexane was then added to produce a white solid. Yield: 70 mg
(88%). Anal. Calcd for C30H29Au2Cl2NP2: C, 38.73; H, 3.14;
N, 1.51. Found: C, 38.94; H, 3.26; N, 1.49. FTIR (CH2Cl2):
=
[PdCl2{(PPh2)2C C(CH3)(NHPh)}] (14). To a solution of 6b
(40 mg, 0.06 mmol) in THF (20 mL) at -78 ◦C, 0.043 mL of MeLi
1.4 M (0.06 mmol) were added. The mixture was then allowed
to reach room temperature with stirring and then distilled water
(0.03 mL) was added. The mixture was filtered over diatomaceous
earth and the filtrate concentrated to 5 mL. Addition of hexane
(15 mL) resulted in the precipitation of a yellow solid. Yield: 33 mg
(83%). Anal. Calcd for C33H29Cl2NP2Pd: C, 58.39; H, 4.31; N,
2.06. Found: C, 58.39; H, 4.22; N, 2.13. FTIR (nujol): n(N–H)
n(C C N) 2068 (s) cm ; 31P{ H} NMR (CD2Cl2): d 34.1 (s); 1H
-1
1
= =
NMR (CD2Cl2): d 0.76 (s, 9 H, C(CH3)3), 7.5–7.7 (m, 20 H, Ph);
13C{ H} NMR (CD2Cl2): d 30.3 (s, C(CH3)3), 62.8 (s, C(CH3)3),
1
1
3347 cm-1; 31P{ H} NMR (CDCl3): d -38.9 (d,2JPP = 22, PPh2),
= =
148.9 (s, P2C C N).
-31.1 (d,2JPP = 22, PPh2); 1H NMR (CDCl3): d 1.81 (s, 3H, CH3),
= =
[Au2Cl2{(Ph2P)2C C NPh}] (9b). This was prepared simi-
6.7–8.1 (m, 26 H, NH, Ph).
= =
larly to 9a starting from (Ph2P)2C C NPh (40 mg, 0.08 mmol)
t
= =
[Au2Me2{(Ph2P)2C C N Bu}] (15a). To a suspension of the
and AuCl(THT) (56 mg, 0.16 mmol). Yield: 66 mg (84%). Anal.
complex 4a (40 mg, 0.04 mmol) in THF (10 mL) was added 54 mL
(0.08 mmol) of MeLi (1.6 M) at -78◦ C. The reaction mixture
was stirred until the solution reached room temperature and was
then concentrated in vacuo until a precipitate started to appear;
precipitation of the product was completed by addition of hexane
to afford a white solid. Yield: 31 mg (81%). Anal. Calcd for
C32H35Au2NP2: C, 43.21; H, 3.97; N, 1.57. Found: C, 43.07; H,
Calcd for C32H25Au2Cl2NP2: C, 40.44; H, 2.65; N, 1.47. Found: C,
-1
= =
40.76; H, 2.87; N, 1.48. FTIR (CH2Cl2): n(C C N) 2036 (s), cm ;
31P{ H} NMR (D2O/CH2Cl2): d 35.2 (s);1H NMR (CD2Cl2): d
1
6.5–7.9 (m, 25 H, Ph).
t
=
= =
[Cu(FBF3){(Ph2P O)2C C N Bu}2][BF4] (11). To a dichlo-
t
=
= =
romethane solution (10 mL) of (Ph2P O)2C C N Bu 10 (50 mg,
9288 | Dalton Trans., 2009, 9280–9290
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Table 5 Crystallographic data for 3a, 5b and 11
Compound
3a
5b·C6H14
11·2CHCl3
Empirical formula
Formula weight
cryst syst
C60H58Ag2Cl2N2O8P4
1345.60
Monoclinic
0.20 ¥ 0.15 ¥ 0.12
P21/n
C102H89Ag3ClI2N3O4P6·C6H14
C62H60B2Cl6CuF8N2O4P4·2CHCl3
2219.44
1470.86
Triclinic
0.22 ¥ 0.07 ¥ 0.02
P-1
12.8216(5)
19.2320(7)
20.9922(8)
110.960(2)
104.228(2)
92.629(3)
4634.1(3)
2, 1.591
200(2)
1.54178
11.933
2216
Orthorhombic
0.25 ¥ 0.22 ¥ 0.20
Pbca
19.6068(2)
17.5173(2)
39.3124(5)
90
Crystal size (mm3)
space group
˚
a (A)
9.6256(2)
˚
b (A)
13.3816(3)
22.2405(4)
90
96.0440(10)
90
2848.78(10)
2, 1.569
120(2)
˚
c (A)
a (◦)
b (◦)
g (◦)
90
90
3
˚
V (A )
13502.2(3)
8, 1.455
120(2)
1.54178
4.128
Z, density (Mg/m3)
T (K)
˚
wavelength (A)
1.54178
7.906
1368
m (mm-1)
F (000)
6044
q range for data collection (deg)
Reflections collected/unique
Data/restraints/parameters
Final R indices (I > 2s(I))
3.86 < q < 65.00
43690/4865 [R(int) = 0.044]
4865/0/353
R1 = 0.0803
wR2 = 0.2146
R1 = 0.0892
wR2 = 0.2210
1.063
2.35 < q < 65.00
27111/15745 [R(int) = 0.0678]
15745/953/1051
R1 = 0.0536
wR2 = 0.1537
R1 = 0.0660
wR2 = 0.1654
1.084
3.57< q <69.99
71577/12679 [R(int) = 0.0250]
12679/342/839
R1 = 0.0480
wR2 = 0.1293
R1 = 0.0692
wR2 = 0.1405
1.059
R indices (all data)
GOF
6.47 (d, 2 H, 3JHH = 8 Hz, o-NPh), 6.99 (s, NH), 7.1–8.0 (m, 23H,
-1
1
4.11; N, 1.45. FTIR (THF): n(C C N) 2050 (s) cm ; 31P{ H}
= =
1
Ph). 13C{ H} NMR (CD2Cl2): d 20.4 (d, 3JCP = 34 Hz, CH3), 98.1
1
NMR (CD2Cl2): d 45.5 (s); H NMR (CD2Cl2): d 0.32 (t, 6 H,
2
(dd, 1JCP = 41 Hz, 1JCP = 20 Hz, P2C C), 162.4 (d, JCP = 40 Hz,
3JHP = 4 Hz, AuCH3), 0.70 (s, 9 H, C(CH3)3), 7.4–7.8 (m, 20 H,
=
=
P2C C).
Ph).
= =
[Au2Me2{(Ph2P)2C C NPh}] (15b). The compound was pre-
X-Ray crystallography
pared from 4b (40 mg, 0.04 mmol) and 53 mL (0.08 mmol) of
MeLi (1.6 M) by following the same method described for 15a.
Yield: 30 mg (79%). Anal. Calcd for C34H31Au2NP2: C, 44.90; H,
3.44; N, 1.54. Found: C, 44.55; H, 3.33; N, 1.45. FTIR (THF):
Suitable single crystals of 3a, 5b·C6H14 and 11·2CHCl3 for X-ray
diffraction were selected (Table 5). Data collection was performed
at 120(2) K for 3a and 11·2CHCl3, and at 200(2) K for 5b·C6H14.
Crystals were covered with perfluorinated ether. The crystals
were mounted on a Bruker-Nonius KappaCCD single crystal
diffractometer. The structures were solved, using the WINGX
package,29 by direct methods (SHELXS-97) and refined by using
full-matrix least-squares against F2 (SHELXL-97).30 All non-
hydrogen atoms were anisotropically refined and hydrogen atoms
were geometrically placed and left riding on their parent atoms.
For the three structures full-matrix least-squares refinements were
-1
1
n(C C N) 2027 (s) cm ; 31P{ H} NMR (CD2Cl2): d 47.1 (s); 1H
NMR (CD2Cl2): d 0.41 (t, 6 H, 3JHP = 4 Hz, AuCH3), 7.1–8.0 (m,
25 H, Ph).
= =
=
(PPh2)2CHC( O)(NHPh) (16). To a solution of [PdCl2-
=
{(PPh2)2CHC( O)(NHPh)}] (12) (40 mg, 0.06 mmol) in
dichloromethane (15 mL) a saturated aqueous solution of KCN
(0.2 mL) was added, and the mixture vigorously stirred for 40 min.
The solution was then filtered off through diatomaceous earth and
concentrated to 2 mL. Addition of hexane (10 mL) afforded a
white solid, which was filtered off and dried under vacuum. Yield:
28 mg, 95%. Anal. Calcd for C32H27NOP2: C, 76.33; H, 5.40; N,
2.78. Found: C, 75.99; H, 5.32; N, 2.88. FTIR (nujol): n(N–H)
carried out by minimizing Rw(Fo - Fc )2 with the SHELXL-97
weighting scheme and stopped at shift/err < 0.001.
2
2
In 3a the refinement converges with a discrepancy index
R1 = 8.03% and the difference-Fourier map shows a prominent
˚
peak placed at 1.01 A from the Ag atom. Many attempts to
-1
1
3374, n(C O) 1660 cm ; 31P{ H} NMR (CDCl3): d -11.6 (s); 1H
=
improve the resolution were made including using lower symmetry
groups, however the resolutions led to a poorer agreement value,
unrealistic geometry of the different rings present in the molecule
and a high peak near each Ag atom was still appearing in
the Fourier map. A twinning treatment was performed but no
better solution was reached. Finally the peak was modelled as
disordered but again the obtained solution did not make chemical
sense. In 5b·C6H14 one phenyl group and the perchlorate anion
were disordered in two positions, this disorder was modeled. The
disordered phenyl group was fitted to a regular hexagon in each
position using the AFIX 69 instruction and the carbon atoms
NMR (CDCl3): d 4.21 (br, 1H, P2CH), 6.7–8.0 (26 H, Ph + NH).
13C{ H} NMR (CD2Cl2): d 46.6 (t, 1JCP = 31 Hz, P2CH) C(CH3)3),
1
=
166.9 (s, C O).
=
(PPh2)2C C(CH3)(NHPh) (17). This compound was pre-
=
pared from [PdCl2{(PPh2)2C C(CH3)(NHPh)}] (14) (40 mg,
0.06 mmol) by following the same method described for 16. Yield:
28 mg, 92%. Anal. Calcd for C33H29NP2: C, 79.03; H, 5.83; N,
2.79. Found: C, 78.70; H, 5.64; N, 2.81. FTIR (nujol): n(N–H)
3366 cm-1; 31P{ H} NMR (CDCl3): d -21.1 (d, 2JPP = 7 Hz, PPh2),
1
-0.6 (d, 2JPP = 7 Hz, PPh2); 1H NMR (CDCl3): d 2.46 (s, 3H, CH3),
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were left anisotropic. Geometrical restraints (DFIX) were applied
to the perchlorate anion. Also, a molecule of hexane crystallized
with every molecule of the compound; this solvent molecule was
found in the difference Fourier map but was very disordered and
it was not possible to get a chemically sensible model for it, so the
Squeeze procedure31 was used to remove its contribution to the
structure factors. SIMU and DELU restraints were applied as well.
For 11·2CHCl3 one of the chloroform molecules was disordered
in two positions and was modeled. Some SIMU restraints were
applied in this structure.
10 A. Codina, O. Crespo, E. J. Ferna´ndez, P. G. Jones, A. Laguna, J. M.
Lo´pez-de-Luzuriaga and M. E. Olmos, Inorg. Chim. Acta, 2003, 347,
9.
11 (a) H. Schmidbaur, A. Wohlleben, U. Schubert, A. Frank and G.
Huttner, Chem. Ber., 1977, 110, 2751; (b) L. Liou, C. Liu and J. Wang,
Acta Crystallogr., Sect. C: Cryst. Struct. Commun., 1994, C50, 538.
12 (a) Effendy, C. D. Nicola, M. Nitiatmodjo, C. Pettinari, B. W. Skelton
and A. H. White, Inorg. Chim. Acta, 2005, 358, 735; (b) T. C. Deivaraj
and J. J. Vittal, J. Chem. Soc., Dalton Trans., 2001, 322.
13 (a) V. W. Yam, W. K. Fung and K. Cheung, Organometallics, 1997, 16,
2032; (b) K. Matsumoto, R. Tanaka, R. Shimomura, C. Matsumoto
and Y. Nakao, Inorg. Chim. Acta, 2001, 322, 125; (c) C. Nicola, Effendy,
F. Fazaroh, C. Pettinari, B. W. Skelton, N. Somers and A. H. White,
Inorg. Chim. Acta, 2005, 358, 720.
14 (a) R. Aumann, Angew. Chem., Int. Ed. Engl., 1988, 27, 1456; (b) T.
Sielisch and U. Behrens, J. Organomet. Chem., 1986, 310, 179; (c) R.
Fandos, M. Lanfranchi, A. Otero, M. A. Pellinghelli, M. J. Ruiz and
J. H. Teuben, Organometallics, 1997, 16, 5283; (d) A. Antin˜olo, A.
Otero, M. Fajardo, R. Gil-Sanz, M. J. Herranz, C. Lo´pez-Mardomingo,
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Ziegler and U. Behrens, J. Organomet. Chem., 1992, 423, C16–C19; (f) T.
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379.
Acknowledgements
This work was supported by the Spanish Ministerio de Educacio´n
y Ciencia (PGE and FEDER funding, Project CTQ2006-10035)
and Factor´ıa de Cristalizacio´n (CONSOLIDER-INGENIO CSD
2006-00015). R.Q. thanks the Ministerio de Ciencia e Innovacio´n
for a contract (Programa Ramo´n y Cajal).
15 F. Marqu´ınez, PhD Thesis, Universidad de Oviedo, 2002.
16 D. K. Saha, S. Padhye, C. E. Anson and A. K. Powell, Inorg. Chem.
Commun., 2002, 5, 1022.
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22 Crystal data for 13-I: C90H89Cu2N3O2P6.(BF4)2.(CH2Cl2)2, Mr
=
1901.01, crystal size 0.42 ¥ 0.38 ¥ 0.34 mm3, Monoclinic, space group
˚
˚
˚
P21/c, a = 14.212(3) A, b = 40.569(8) A, c = 17.545(4) A, b =
◦
105.41(3) , V = 9752(3) A , Z = 4, rcalcd = 1.295 mg m-3, m =
3
˚
-1
˚
0.705 mm , Mo-K a radiation (l = 0.71073 A). Data collection
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2
-3
˚
wR2(F ) = 0.4585). Largest diff. peak/hole 1.905/-0.694 e A .
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9290 | Dalton Trans., 2009, 9280–9290
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