New palladium (substituted 1,10-phenanthroline) bis(methoxycarbonyl) complexes [Pd(L-L)(CO2CH3)2]: Preparation and structural features

Article abstract of DOI:10.1016/S0022-328X(98)00742-6

New complexes of general formula Pd(L-L)(CO₂CH₃)₂ (L-L=1,10-phenanthroline 1; 2,9-dimethyl-1,10-phenanthroline 2; 4,7-dimethyl-1,10-phenanthroline 3; 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline 4, 3,4,7,8-tetramethyl-1,10-phenanthroline 5; and 4,7-diphenyl-1,10-phenanthroline 6) were prepared either by exchange reaction between Pd(bipyridine)(CO₂CH₃)₂ 7 and the appropriate free ligand or by reacting Pd(L-L)Cl₂ suspended in MeOH under carbon monoxide, at room temperature, in the presence of a base. The structure of 1 was determined ab initio from X-ray powder diffraction data by using a simulated annealing technique and refined by the Rietveld method. 1 crystallizes in the orthorhombic Pbca space group with cell parameters a=8.0787(4), b=16.2797(8), c=22.843(1) A and Z=8.

Full text of DOI:10.1016/S0022-328X(98)00742-6

Journal of Organometallic Chemistry 566 (1998) 37–43
New palladium (substituted 1,10-phenanthroline) bis(methoxycarbonyl)
complexes [Pd(L–L)(CO2CH3)2]: preparation and structural features
Roberto Santi a, Anna Maria Romano a,*, Rossella Garrone a, Roberto Millini b
a ‘Ist. G. Donegani’-EniChem, Via Fauser, 4-28100 No6ara, Italy
b Eniricerche S.p.A., Via Maritano, 26-20097 S. Donato Mil. (MI), Italy
Received 4 December 1997
Abstract
New complexes of general formula Pd(L–L)(CO2CH3)2 (L–L=1,10-phenanthroline 1
4,7-dimethyl-1,10-phenanthroline 3; 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline 4, 3,4,7,8-tetramethyl-1,10-phenanthroline 5
and 4,7-diphenyl-1,10-phenanthroline 6) were prepared either by exchange reaction between Pd(bipyridine)(CO2CH3)2 7
appropriate free ligand or by reacting Pd(L–L)Cl2 suspended in MeOH under carbon monoxide, at room temperature, in the
presence of a base. The structure of 1 was determined ab initio from X-ray powder diffraction data by using a simulated annealing
technique and refined by the Rietveld method. 1 crystallizes in the orthorhombic Pbca space group with cell parameters
6
; 2,9-dimethyl-1,10-phenanthroline 2
6
;
;
6
6
6
6
6 and the
6
6
˚
a=8.0787(4), b=16.2797(8), c=22.843(1) A and Z=8. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Palladium; Phenanthrolines; Alkoxycarbonyl; Carbonylation; X-ray structure
tris(2-diphenylphosphinoethyl)amine) was synthesized
1. Introduction
by ethoxide ion attack on Ni(np3)(CO), while
Ni(pnp)(CO2CH3)2 [9], (pnp=2,6-bis(diphenylphosphi-
nomethyl)pyridine) was obtained from Ni(pnp)Cl2 and
amines under CO in methanol.
Platinum alkoxycarbonyl complexes have been pre-
pared by reacting Pt(L–L)Cl2, where L–L are phos-
Transition metal alkoxycarbonyl derivatives have
been recognized as key intermediates in many relevant
homogeneous catalytic processes involving alkanols
and carbon monoxide [1]. The synthesis of carbonates
and oxalates [2], the hydrocarboalkoxylation of alkenes
[3] and alkynes [4,5] to the respective saturated and
unsaturated esters, the copolymerization of alkenes
with CO [6] appear to involve alkoxycarbonyl metal
intermediates.
Due to their versatility, the alkoxycarbonyl com-
plexes of transition metals have been studied exten-
sively. The methoxycarbonyl iridium complex
Ir(PPh3)2(CO2CH3)(CO)2 was prepared by nucleophilic
attack of the methoxide group on the carbonyl ligand
in Ir(PPh3)2(CO)(OCH3) [7]. Analogously, the ethoxy-
carbonyl complex [Ni(np3)(CO2Et)2]BPh4 [8] (np3=
phorous
chelating
ligands,
such
as
dppe
(dppe=1,2-bis(diphenylphospinoethane) [10], pnp and
also dppf ligands (dppf=1,1%-bis(diphenylphos-
phino)ferrocene) [11] with CO in methanol, in the pres-
ence of a base.
Similarly, palladium bis(alkoxycarbonyl) complexes
Pd(CO2R)2(PPh3)2 [12] were synthesized by carbonyla-
tion of PdCl2(PPh3)2 suspended in MeOH with carbon
monoxide, in the presence of an amine, whereas Pd-
Cl(CO2R)(PPh3)2 was prepared from PdCl2(PPh3)2 un-
der CO for a shorter reaction time [13] or by oxidative
addition of an alkyl chloroformate to a Pd(0) complex,
such as Pd(PPh3)4 [14]. The acetato(carbomethoxy)
complex Pd(OAc)(CO2CH3)(PPh3)2 was analogously
* Corresponding author. Tel.: +39 32 1447532; fax: +39 32
1447425.
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00742-6

38
R. Santi et al. / Journal of Organometallic Chemistry 566 (1998) 37–43
Table 1
7+(L–L)“Pd(L–L)(CO2CH3)2+bipy
(1)
Preparation of Pd(L–L)(CO2CH3)2 by exchange reactiona or by
sodium methoxide and or by potassium carbonate based procedures
or by reaction of Pd(L–L)Cl2 with a base, such as
sodium methoxide or potassium carbonate, in 1:2.2
molar ratio, in the presence of the free ligand (10%
weight in respect to Pd(L–L)Cl2) under carbon monox-
ide at room temperature (Table 1).
The most effective procedure to synthesize the palla-
dium complexes uses sodium methoxide, as the base,
yields being higher than those obtained by exchange
reaction or with potassium carbonate.
Com-
pound
Procedure
Colour
Exchange
Yield (%)
MeONa/CO K2CO3/CO
Yield (%)
Yield (%)
1
6
77
0
57
0
53
85
—
83
71
84
70
70
86
83
80
0
Yellow
Yellow
Yellow
Yellow
Light yellow
Yellow
Light green
2
6
3
6
37
20
18
67
55
4
6
The preparation of complex 26 failed both by ligand
5
6
exchange and by using potassium carbonate as base.
Moreover, the ligand exchange always failed when the
ligand bore substituents in both 2 and 9 positions,
independently from their steric hindrance, as in the case
6
6
7
6
Conditions: 20 h at room temperature.
a Reaction exchange carried out between Pd(bipy)(CO2
the corresponding free ligand (for further details see experimental
section).
6
CH3)2 7 and
of complexes 26 and 46 . Furthermore, all the attempts to
isolate the Pd(L–L)(CO2CH3)2 complex, where L–L is
2,9-diphenyl-1,10-phenanthroline, were unsuccessful
probably due to the bulky substituents in 2 and 9
positions. The synthesis of palladium bis(methoxycar-
prepared by treating Pd(OAc)2(PPh3)2 under CO [15].
Although palladium complexes with nitrogen chelating
ligands are very common, only a few examples of
bonyl)
complexes
by
ligand
exchange
was
unprecedented.
Added free nitrogen ligand has the effect to increase
the complexes stability during the carbonylation reac-
tions; indeed, the yield in complex 16 was 83% against
72% without added free 1,10-phenanthroline. More-
over, the added ligand allows us to obtain
palladium
bis-(methoxycarbonyl)
complexes
Pd(bipy)(CO2CH3)2, bearing a bipyridine (bipy) ligand
are known [16,17].
We now report the synthesis and spectroscopic char-
acterization of bis(methoxycarbonyl) palladium (II)
complexes Pd(L–L)(CO2CH3)2, bearing substituted
1,10-phenanthrolines (L–L) as ligand, and the crystal
structure of 16 , determined ab initio from X-ray powder
diffraction data by using
technique.
Pd(bipy)(CO2CH3)2 76 with a yield of 86% in respect to
the 62% reported by Hanson and coworkers [16].
The compounds obtained were characterized by ana-
a simulated annealing
1
lytical, mass, IR and H-NMR spectroscopy (Table 2),
showing
a perfect agreement with the proposed
structure.
IR spectra showed adsorption bands in the regions
1680–1590 cm−1 and 1100−1030 cm−1, assigned to
wCꢀO and wC–O asymmetric and symmetric stretching,
respectively. The double adsorptions for both wCꢀO and
wC–O asymmetric and symmetric stretching, were as-
cribed to conformational cis and trans isomers [13]. No
correlations were found between the carbonyl stretch-
ing adsorptions and the ligand pKa values [18].
2. Results and discussion
2.1. Synthesis of Pd(L–L)(CO2CH3)2
Complexes Pd(L–L)(CO2CH3)2 were prepared in
good yield by ligand exchange reaction of complex
Pd(bipy)(CO2CH3)2 76 with the appropriate free ligand
(Eq. (1)):
Table 2
Analytical, mass and IR data of Pd(L–L)(CO2CH3)2 complexes in nujol mull
Compound Analytical data calc. (found) (%)
m/e
pKa
wCꢀO (cm−1
)
nC–O (cm−1
)
C
H
N
(FAB)
1
6
47.52 (47.60)
50.00 (50.02)
50.00 (50.07)
60.00 (59.80)
26.08 (25.59)
58.64 (58.70)
44.20 (44.31)
44.21 (4435)
3.46 (3.40)
4.17 (4.13)
4.17 (4.19)
4.64 (4.56)
5.65 (5.70)
4.13 (4.20)
3.68 (3.62)
2.89 (2.93)
6.93 (7.01)
6.48 (6.51)
6.48 (6.45)
5.00 (5.10)
6.08 (6.10)
5.26 (5.31)
7.36 (7.42)
7.36 (7.25)
404
432
432
560
464
532
380
380
4.86
6.17
5.94
—
6.31
4.84
4.44
—
1665–1645
1680–1650
1640–1625
1675–1640
1640–1600
1670–1640
1650–1620
1670
1100–1050
1070–1030
1080–1040
1080–1045
1090–1050
1080–1030
1070–1020
1030
2
6
3
6
4
6
5
6
6
6
7
6
8
6

R. Santi et al. / Journal of Organometallic Chemistry 566 (1998) 37–43
39
Table 3
1H-NMRa data for compounds 1
–66
6
Com-
pound
l (H2)
l (H3)
l (H4)
l (H5)d
l (H6)
l (H7)
l (H8)
l (H9)
l (H-
COOMe)
l (HSubst.)
1
6
8.90 (dd)
—
8.72 (d)
—
7.68 (dd)
7.53 (d)
7.52 (d)
7.80 (s)
8.41(dd)
8.24 (d)
—
7.86(s)
7.86(s)
8.41 (dd)
8.24 (d)
—
7.68 (dd)
7.53 (d)
7.52 (d)
7.80 (s)
8.90 (dd)
—
8.72 (d)
—
3.77 (s)
3.70 (s)
3.63 (s)
3.70 (s)
—
2
6
7.79 (s)
8.10 (s)
7.45 (s)
7.79 (s)
8.10 (s)
7.45 (s)
2.86 (s, CH3)
2.80 (s, CH3)
2.90 (s, CH3)
7.5–7.6 (m,
Ph)
3
6
4
6
—
—
5
6
8.70 (s)
9.14 (d)
9.25 (dd)
—
—
8.10 (s)
7.99 (s)
7.98 (s)
8.10 (s)
7.99 (s)
7.98 (s)
—
—
8.70 (s)
9.14 (d)
8.87 (dd)
3.70 (s)
3.71 (s)
3.86 (s)
2.70 (s, CH3)
2.50 (s, CH3)
7.5–7.6 (m,
Ph)
66
7.80 (d)
8.6 (m)
—
—
7.80 (d)
8.6–8.7 (m)
86
7.8 (m)
7.83 (m)
—
Spectra were recorded immediately after dissolution.
s, singlet; d, doublet; dd, double doublet; m, multiplet.
a Spectra were recorded in CD2Cl2. l (1H) values in ppm from TMS as internal standard.
1
The H-NMR analysis (Table 3) were consistent with
the formation of Pd(L–L)(CO2CH3)2, showing singlets
in the 3–4 ppm region due to the methoxy group
protons; the spectra were obtained in CD2Cl2, since in
CDCl3 the methoxycarbonyl groups react in a few
minutes with the catalytic action of HCl, usually con-
tained in trace amounts in chloroform, affording
spectrum of the mixture of complex Pd(phen)2(PF6)2 96 ,
prepared according to the literature [20], together with
one equivalent of the phenanthroline ligand and two
equivalents of the acid phenHPF6, which showed the
same resonance patterns of a mixture in 1:1:2 molar
ratio of 9
6 :phen:phenHPF6.
The alkoxycarbonyl palladium complex 1
6
, suspended
Pd(phen)Cl(CO2CH3) 8
6
in 70% yield (Eq. (2)) ([11]a):
(2)
was character-
in methanol/water (10/1 v/v) at 65°C, decomposes to
black Pd(0), with a concomitant formation of free
phenanthroline.
1+HCl“Pd(phen)Cl(CO2CH3)+CO+MeOH
Compound Pd(phen)Cl(CO2CH3) 8
6
ized by 1H-NMR (Table 3), it showed the methyl
singlet of the methoxycarbonyl group shifted from 3.77
to 3.86 ppm (Table 3); moreover, the two protons in
position 2 and 9 gave two signals (H2 at 9.25 ppm and
H9 at 8.87 ppm).
2.3. Crystal structure of 1
6
Since all attempts to grow crystal of 1
6
suitable for
single crystal X-ray analysis failed, the crystal structure
determination was performed ab initio by using the
simulated annealing technique and refined by the Ri-
etveld method (see Section 3). The complexity of the
molecule imposed the use of constraints during the
refinement, performed by defining four rigid bodies (the
Pd atom, the phen ligand and the two methoxycarbonyl
groups) with fixed geometry but free to rototranslate
with respect to a defined pivot atom. In spite of the
hard constraints imposed, the refinement led to an
excellent reproduction of the experimental XRD pat-
tern, as demonstrated by the low residual error index
factors reported in Table 4, together with the main
crystallographic data.
2.2. Reacti6ity of Pd(L–L)(COOMe)2
When heated at 50°C for 8 hrs in methanol, complex
16 reacted with two equivalents of phenanthrolinium
hexafluophasphate phenHPF6, an acid bearing a non-
coordinating anion, prepared according to the literature
[19], to yield Pd(phen)2(PF6)2 9
6 (Eq. (3)):
1+2phenHPF6“Pd(phen)2(PF6)2+2CO +2MeOH
+phen
(3)
Four equivalents of the acid were needed, however,
to displace the reaction to right, as shown by the
change of the suspension colour from yellow to pink.
The reaction residue was washed several times with
diethyl ether, to eliminate the phenanthroline still
present. The 1H-NMR spectrum (in CD3CN) of the
solid residue showed adsorptions attributable to a sin-
gle species. These results are attributable to a dynamic
equilibrium between all the species present in solution,
Fractional atomic coordinates for non-H atoms and
the main geometrical features of 16 are reported in
Tables 5 and 6, respectively. It must be pointed out that
estimated S.D. values reported in Tables 5 and 6 are
surely underestimated as a consequence of the rigid-
body refinement scheme adopted. In fact, this approach
allows the accurate determination of the location and
orientation of the different groups with known geome-
try and is generally used to reduce the number of
1
as brought about by the comparison with the H-NMR

40
R. Santi et al. / Journal of Organometallic Chemistry 566 (1998) 37–43
Table 4
Table 6
Selected bond lengths (A) and angles (°) for 1
˚
Data collection and crystallographic data for 1
6
6
Formula
C16H14N2O4Pd
404.70
Orthorhombic
Pbca
8.0787(4)
16.2797(8)
22.843(1)
3004.3(2)
1.7894
Pd(1)–N(2)
Pd(1)–C(16)
C(16)–Pd(1)–C(20) 92.5(5)
N(15)–Pd(1)–C(16) 174.3(5)
N(2)–Pd(1)–C(16)
Pd(1)–N(2)–C(7)
Pd(1)–N(15)–C(14) 131.5(6)
Pd(1)–C(16)–O(18) 126.7(10) Pd(1)–C(16)–O(17) 118.2(9)
Pd(1)–C(20)–O(22) 120.6(8) Pd(1)–C(20)–O(21) 124.4(8)
2.111(9)
1.981(14) Pd(1)–C(20)
Pd(1)–N(15)
2.124(8)
1.992(12)
Molecular weight
Crystal system
Space group
N(15)–Pd(1)–C(20) 93.2(4)
N(2)–Pd(1)–C(20)
N(2)–Pd(1)–N(15)
Pd(1)–N(2)–C(3)
172.6(4)
82.5(3)
131.0(5)
˚
a (A)
92.1(4)
108.8(6)
˚
b (A)
˚
c (A)
Pd(1)–N(15)–C(11) 108.7(5)
3
˚
V (A )
Dcalc. (mg m−3
)
˚
Radiation
Cu–Kh (u=1.54178 A)
Linear absorption coefficient 104.03
v (cm−1
Sample
)
of the location and orientation of the different groups,
but does not give any possibilities to refine the internal
geometry of the rigid-bodies determining the possible
distortions of the groups. To do that, the refinement of
the positions of the individual non-H atom failed,
probably because of the exessive numbers of parame-
ters involved in the refinement. In any case, the results
obtained is, in our opinion, very satisfactory demostrat-
ing that is it possible to solve and refine the structure of
relatively complex molecules from X-ray diffraction
data.
Yellow-brown powder
Diffractometer
Scan type
Siemens D500
q/q
2q range (°)
5–80
Step size (°2q)
Accumulation time (s/step)
Number of steps
Number of reflections
Rp
0.03
10
2501
910
0.068
Rwp
0.088
Atomic scattering factors
Int. Tables of Crystallography Vol.
IV
The molecular structure, with the atom labelling
scheme adopted, is shown in Fig. 1. As expected, the
Pd(phen)(CO2CH3)2 complex displays a square planar
parameters to be refined when the diffraction data do
not contain sufficient information for treating them (in
other words, when the ratio reflections/parameters is
low). The refinement with the rigid-body approxima-
tion then leads to a sufficiently accurate determination
˚
coordination (Pd is 0.044(3) A from the plane through
N(2), N(15), C(15) and C(20)). The methoxycarbonyl
groups are crystallographically inequivalent, so that the
possible internal symmetry of the molecule, observed in
the structure of the analogous complex with bipyridine
[17], is lost. The Pd(1)–C(16) and Pd(1)–C(20) bond
length are not significantly different within the standard
uncertainty and are very close to the analogous bond
Table 5
Fractional atomic coordinates of non-H atoms for 1
2
˚
˚
x
y
z
Biso (A )
observed in Pd(bipy)(CO2CH3)2 (1.989(9) A) [17]. The
same is true for the Pd(1)–N(2) and Pd(1)–N(15)
bonds (Table 6)
Pd(1)
N(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
N(15)
C(16)
O(17)
O(18)
C(19)
C(20)
O(21)
O(22)
C(23)
0.2100(3)
0.0838(10)
−0.0898(2)
−0.1920(6)
−0.2565(6)
−0.3156(6)
−0.3102(6)
−0.2456(6)
−0.1865(6)
−0.2403(6)
−0.1758(6)
−0.1168(6)
−0.1222(6)
−0.0523(6)
0.0067(6)
0.1514(2)
0.1867(3)
0.1594(3)
0.1930(3)
0.2542(3)
0.2815(3)
0.2478(3)
0.3426(3)
0.3699(3)
0.3361(3)
0.2751(3)
0.3634(3)
0.3298(3)
0.2686(3)
0.2412(3)
0.0701(6)
0.0382(6)
0.0428(6)
0.36
0.54
0.74
0.74
0.74
0.74
0.74
0.74
0.74
0.74
0.74
0.74
0.74
0.74
0.54
0.74
0.81
0.81
0.74
0.74
0.81
0.81
0.74
−0.0002(10)
−0.0813(10)
−0.0787(10)
0.0054(10)
0.0866(10)
0.0082(10)
0.0922(10)
0.1733(10)
0.1705(10)
0.2573(10)
0.3383(10)
0.3357(10)
0.2516(10)
0.1659(15)
0.0522(15)
0.2398(15)
0.0310(15)
0.3107(13)
0.2862(13)
0.4102(13)
0.4804(13)
0.0014(6)
−0.0631(6)
−0.1261(7)
−0.0838(7)
−0.1815(7)
−0.1225(7)
0.0154(7)
0.0824(7)
0.0174(7)
0.0975(7)
−0.0174(6)
0.1247(4)
0.1479(4)
0.0768(4)
0.0707(4)
Fig. 1. Molecular structure of 16 with the atomic numbering scheme
adopted.

R. Santi et al. / Journal of Organometallic Chemistry 566 (1998) 37–43
41
3. Experimental section
throline (10% weight in respect to Pd(phen)Cl2) in 25
cm3 of methanol. The resulting suspension was stirred
under CO for 20 h at room temperature. After this
time, the solvent was distilled and methylene chloride
added; the suspension was filtered on celite to remove
the NaCl; then the solution distilled under reduced
pressure and the solid dried in vacuo (yield=83%).
3.1. General comments
All reactions were performed under argon atmo-
sphere, using the Schlenk tube techniques. Methanol
was distilled under argon from CaH2 and stored on 4 A
˚
molecular sieves. Sodium methoxide was prepared by
reacting sodium metallic with anhydrous methanol.
Pd(L–L)Cl2 [21,22] and PhenHPF6 were prepared ac-
cording to the literature [19]. Phenanthrolines and
Pd(MeCN)2Cl2 were obtained from Fluka and Aldrich,
respectively, and used as received. Carbon monoxide
was purchased from Rivoira.
3.4. Preparation of Pd(phen)(CO2CH3)2 1
potassium carbonate procedure
6
by the
We
report
only
the
preparation
of
and 7
Pd(phen)(CO2CH3)2; the complexes 2
6
, 3
6
, 4
6
, 5
6
, 6
6
6
were similarly prepared. To a suspension of 1.00 g of
Pd(phen)Cl2 (2.80 mmol) and 0.100 g of 1,10-phenan-
throline (10% by weight in respect to Pd(phen)Cl2) in 25
cm3 of methanol was added under argon 0.8 g K2CO3
(5.79 mmol). The resulting suspension was stirred under
CO for 20 h at room temperature. Work-up of com-
plexes was analogous to the experiment carried out
1H- and 13C-NMR spectra were recorded on 200
MHz Brucker Electrospin AG 200 BZH Instrument,
while IR spectra were recorded using a Perkin Elmer
1420 Instrument. FAB MS were recorded on a Finni-
gan MAT M scan Instrument, using m-nitrobenzylalco-
hol as a matrix.
with sodium methoxide. The yield of 1
6
was 80%.
3.2. Preparation of Pd(phen)(CO2CH3)2 1
reaction
6 by exchange
3.5. Preparation of Pd(phen)(CO2CH3)Cl 8
of Pd(phen)(CO2CH3)2 with CHCl3
6
by reaction
Only the preparation of Pd(phen)(CO2CH3)2 by ex-
change reaction is reported; the complexes 2, 3, 4, 5, 6
and 7 were prepared in an analogous manner. To a
6
6
6
6
6
In a 50 cm3 three necked round-bottom flask, a
solution of 0.15 g of Pd(phen)(CO2CH3)2 (0.37 mmol)
in 25 cm3 of chloroform was stirred under argon at
room temperature for 20 h. After this time, the solvent
was distilled and the residue washed with diethyl ether,
and dried under vacuum, to obtain 0.10 g of pink solid
(yield=71%). 1H-NMR (in CD2Cl2 l referenced to
TMS): 9.25 ppm (dd, 1H); 8.87 ppm (dd, 1H); 8.56 ppm
(m, 2H); 7.98 ppm (s, 2H); 7.83 ppm (m, 2H); and 3.86
(s, 3H). 13C-NMR (in CD2Cl2 l referenced to TMS):
52.71; 125.69; 126.09;127.36; 127.88; 138.73;138.88;
149.91; 153.07; 187.57. IR (in nujol mull): 1670 and
1030 cm−1. Mass spectrum (FAB): m/e=381 (M+1).
6
canary yellow solution of 0.2 g (0.526 mmol) of
Pd(bipy)(CO2CH3)2 in 25 cm3 methanol were added
0.095 g (0.526 mmol) of phenanthroline under argon.
The mixture was vigourously stirred for 20 h at room
temperature. After this period, the solution changed to
lemon yellow. The solid was filtered and washed with
hexane until the bipyridine was completely removed,
and, subsequentially, with diethylether, thus removing
phenanthroline, eventually still present. The lemon yel-
low complex was dried under vacuum with a yield of
77%.
13C-NMR (l ppm, referenced to TMS) of 1
125.26; 127.24; 129.47; 138.38; 145.19; 151.57; 187.61.
13C-NMR (l ppm, referenced to TMS) of 3
: 188.36;
6 : 50.446;
3.6. Reaction of Pd(phen)(CO2CH3)2 with four
equi6alents of PhenHPF6
6
151.09; 147.90; 145.17; 128.96; 125.78; 123.27; 50.29;
19.32.
In a 50 cm3 three necked round-bottom flask, under
argon and at room temperature, was stirred a suspen-
sion of 0.130 g Pd(phen)(CO2CH3)2 (0.32 mmol) in 25
cm3 methanol anhydrous; then, 0.210 g of PhenHPF6
(0.64 mmol) were added. After 20 h, since the reaction
mixture appeared unchanged, it was heated at 60°C and
another two equivalents of acid PhenHPF6 (0.21 g; 0.64
mmol) were added. After 8 h, the suspension changed
to pink and the solid was filtered, washed with diethyl
ether and dried in vacuum, thus obtaining 0.48 g of
pink solid.
13C-NMR (l ppm, referenced to TMS) of 6
6 :
50.15;125.37; 126.00; 128.23; 129.40; 129.93; 130.03;
136.64; 146.82; 151.53; 151.78; 187.96.
3.3. Preparation of Pd(phen)(CO2CH3)2 1
sodium methoxide procedure
6
by the
We
report
only
the
preparation
of
and 7
Pd(phen)(CO2CH3)2; the complexes 2
6
, 3
6
, 46
, 56
, 66
6
were similarly prepared. A 11.50 ml solution of sodium
methoxide (0.55 M) in methanol (6.32 mmol) was
added under argon to a suspension of 1.00 g of
Pd(phen)Cl2 (2.80 mmol) and 0.10 g of 1,10-phenan-
1H-NMR of the pink residue (in CD3CN l refer-
enced to TMS): 9.13 ppm (dd, 4H); 8.96 ppm (dd, 4H);
8.29 ppm (s, 4H); 8.14 ppm (m, 4H). 1H-NMR ob-

42
R. Santi et al. / Journal of Organometallic Chemistry 566 (1998) 37–43
Fig. 2. Experimental (ꢀ), calculated (—) and difference (lower) XRD patterns for 16 .
tained by dosing 9
6
: PhenHPF6: Phen in a molar ratio of
al. for the solution of the structure of
Li3[Co(CN)5]·2DMF [25]. The calculations were per-
1:2:1 (in CD3CN l referenced to TMS): 9.13 ppm (dd,
4H); 8.96 ppm (dd, 4H); 8.29 ppm (s, 4H); 8.14 ppm
(m, 4H). IR (in nujol mull): 850 cm−1. Mass spectrum
formed with the Molecular PD functionality within the
–
Molecular Simulations CATALYSIS software package
[26]. Firstly, the fragment Pd(phen) was placed at the
center of the unit cell and randomly rototranslated
according to a Metropolis Monte Carlo algorithm; at
each step, the XRD pattern was simulated and com-
pared with the experimental one. Once the best fit was
obtained, two –CO2CH3 moieties were added to the
Pd(phen) fragment to obtain a model of the complex
with Pd atom in square planar coordination. Another
run of simulated annealing was performed allowing the
random rotation of the two methoxycarbonyl groups
around the Pd–C bonds. The final model, with residual
error index Rwp=0.21 was then refined using a revised
version [27] of the PREFIN Rietveld program [28]. We
chose this package because it allows the refinement of
diffraction data in the rigid bodies approximations and
the adequate treatment of the peak asymmetry [25],
affecting the reflections in the low angles region of the
XRD pattern. The refinement involved the rototransla-
tion of four rigid bodies: the Pd atom, the phen ligand
and the two methoxycarbonyl moieties. The pseudo-
Voigt peak profile function, with refinable gaussian
character, was used and the breadth of the reflections as
a function of the diffraction angle was modelled with
the Caglioti, Paoletti and Ricci equation [29]. The
instrumental background was defined by a linear inter-
polation of points with refinable intensity, while
isotropic temperature factors were refined by grouping
chemically similar atoms.
of 9
3.7. Crystal structure of Pd(phen)(CO2CH3)2 (1
X-ray powder diffraction (XRD) data for 1
6
(FAB) m/e 233. Calc. for Pd(phen)2+ +: 233.
6
)
6
were
collected at 298 K on a Siemens D500 diffractometer,
operating in the q/q geometry, using Cu–Kh radiation
˚
(u=1.54178 A). Step-scanning procedure, with a step
size 0.03° 2q and 20 s/step accumulation time, was
applied over the 5–80° 2q angular region. Indexing of
the pattern was performed with the TREOR-5 program
[23] by using the interplanar spacings of the first 50
peaks accurately determined with the routine FIT of
the software package DIFFRAC-AT (Siemens). The
pattern was fully indexed with an orthorhombic unit
cell with dimensions: a=8.080(2), b=16.383(4), c=
˚
22.849(9) A. Inspection of the reflections revealed the
systematic extinctions consistent with the space groups
Pbca (no. 61 International Tables for X-ray Crystallog-
raphy), that on the basis of the computed crystal den-
sity, implies the existence of eight molecules of 16 per
unit cell. The centrosymmetric Pbca space group was
initially chosen on the basis of the computed crystal
density for a unit cell containing eight molecules of 16 .
The consistency of the indexing was checked with the
EXTRA program [24] used for extracting the intensities
of the reflections by the full-pattern deconvolution
method. A Patterson map was computed from these
data allowing the localization of the Pd atom; the
successive Fourier and difference Fourier maps were
however unsuccessful. For these reasons the solution of
the structure was attempted by using the simulated
annealing procedure recently applied by Ramprasad et
In spite of the hard constraints introduced, an excel-
lent reproduction of the experimental XRD pattern was
obtained (Fig. 2). It must be pointed out that all the
attempts to improve the quality of the fit by refining the
position of the each non-H atom failed, probably be-

R. Santi et al. / Journal of Organometallic Chemistry 566 (1998) 37–43
43
[10] G. Vasapollo, L. Toniolo, G. Cavinato, F. Bigoli, M. Lan-
franchi, M.A. Peleghelli, J. Organomet. Chem. 296 (1985) 435.
[11] G. Cavinato, L. Toniolo, J. Organomet. Chem. 444 (1993) 65.
[12] M. Hidai, M. Kokura, Y. Uchida, J. Organomet. Chem. 52
(1973) 431.
cause of the excessive number of parameters involved in
the refinement.
[13] R. Bertani, G. Cavinato, L. Toniolo, G. Vasapollo, J. Mol.
Catal. 84 (1993) 165.
Acknowledgements
[14] P. Fitton, M.P. Johnson, J.E. McKeon, Chem. Commun. (1968)
6.
[15] F. Rivetti, U. Romano, J. Organomet. Chem. 154 (1978) 323.
[16] G.D. Smith, B.E. Hanson, J.S. Merola, F.J Waller,
Organometallics 12 (1993) 568.
This work has been sponsored by the Ministero
dell’Universita` e della Ricerca Scientifica e Tecnologica
within a framework of the ‘Programma Nazionale di
Ricerca per la Qualita` della Vita’.
[17] P. Giannoccaro, N. Ravasio, M. Aresta, J. Organomet. Chem.
45 (1993) 243.
[18] G. Clauti, G. Zassinovich, G. Mestroni, Inorg. Chim. Acta 112
(1986) 103.
References
[19] R. Santi, A.M. Romano, F. Panella, G. Mestroni, A. Sessanta O
Santi, It. Pat. 5738 (1996).
[20] A. Bontempi, E. Alessio, G. Mestroni, G. Chanos, J. Mol. Catal.
42 (1987) 67.
[21] B.J. McCormick, E.N. Jaynes, R.L. Kaplan, in: F.A Cotton
(Ed.)., Inorganic Synthesis, vol. 13, McGraw Hill, New York, p.
16.
[22] R.P. Cheng, B. Plankley, J.V. Rund, T.L. Brown, J. Am. Chem.
Soc. 99 (1977) 8413.
[23] P.E. Werner, L. Eriksson, M. Westdahl, J. Appl. Crystallogr. 18
(1985) 367.
[24] A. Altomare, M.C. Burla, G. Cascarano, C. Giacovazzo, A.
Guagliardi, G. Moliteni, G. Polidori, J. Appl. Crystallogr. 28
(1995) 842.
[25] D. Ramprasad, G.P. Pez, B.H. Toby, T.J. Markley, R.M. Pearl-
stein, J. Am. Chem. Soc. 117 (1995) 10694.
[26] Catalysis User Guide, Molecular Simulations, San Diego, Octo-
ber, 1995.
[27] R. Millini, G. Perego, S. Bru¨ckner, Mater. Sci. Forum 71–82
(1991) 239.
[1] L. Beller, B. Cornils, C. D. Frohnig, W. Kohlpaintner, J. Mol.
Catal. A 104 (1995) 17.
[2] (a) D. Delledonne, F. Rivetti, U. Romano, J. Organomet. Chem.
488 (1995) C15. (b) U. Romano, R. Tesei, M. M. Mauri, P.
Rebora, Ind. Eng. Chem. Prod. Res. Dev. 19 (1980) 396. (c) F.
Rivetti, U. Romano, J. Organomet. Chem. 174 (1979) 221.
[3] (a) B. El Ali, H. Alper, J Org. Chem 58 (1993) 3595. (b) B. El Ali
and H. Alper, J. Mol. Catal. 80 (1993) 377. (c) Y. Sugi, K.I.
Bando, Chem. Letters (1976) 727.
[4] (a) A. Scrivanti, U. Matteoli, Tetrahedron Lett. 49 (1995) 9015.
(b) E. Drent, P. Arnoldy, P.H.W. Budzelaar, J. Organomet.
Chem. 455 (1993) 247.
[5] (a) E. Drent, P. Budzelaar, W. Jager, J. Stapersma, EP Appl.
441, 447 (1991). (b) E. Drent, P. Budzelaar, J. Jager, EP Appl.
386, 833 (1990). (c) E. Drent, A. Onno, EP Appl. 271, 144
(1987).
[6] E. Drent, P.H.M. Budzelaar, Chem. Rev. 96 (1996) 663.
[7] M.W. Rees, M.R. Churchill, J.C. Fettinger, J.D. Atwood,
Organometallics 4 (1985) 2179.
[8] C. Bianchini, A. Meli, J. Organomet. Chem. 276 (1984) 413.
[9] A. Sacco, P. Giannoccaro, G. Vasapollo, Inorg. Chim. Acta 83
(1984) 125.
[28] A. Immirzi, Acta Crystallogr. A34 (1978) S348 and Acta Crystal-
logr. B36 (1980) 2378.
[29] G. Caglioti, A. Paoletti, F.P. Ricci, Nucl. Instrum. 3 (1958) 223.
.