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A. Skarzynska et al. / Inorganica Chimica Acta 365 (2011) 204–210
Scheme 1.
For these above reasons, we find investigations of versatile and
920vs, 935vs, 955vs, 988vs, 1011s (C–O–P), and 3490vs
m
m
(O–H)
reactive palladium ligand systems incorporating unexplored
hydrophosphoranes to be of great interest.
262vs, 276vs, 298m, 356vs (Pd–P), m(Pd–Cl).
m
We have been prompted to obtain Pd complexes containing H-
phosphoranes and, as a consequence, to examine catalytic activity
in a C–C bond forming reactions. We focused on two H-spirophos-
phoranes: HP(OCH2CMe2NH)2 and HP(OCMe2CMe2O)2 and the lat-
ter’s congener cyclic H-phosphonate HP(O)(OCMe2CMe2O).
2.2.2. [Pd{P(O)(OCMe2CMe2O)}2]n (2)
A suspension of [Pd(OAc)2] (0.08 g, 0.35 mmol) and HP(O)(OC-
Me2CMe2O) ligand (0.12 g, 0.73 mmol) in toluene (5 cm3) was stir-
red for 24 h until the starting compound reacted and a white–gray
solid was obtained. The product was filtered, washed with diethyl
ether and dried in vacuo (0.10 g, 67%).
Anal. Calc. for C12H24O6P2Pd: C, 33.31; H, 5.59. Found: C, 34.38;
2. Experimental
H, 5.72%; 1H NMR (CD2Cl2): d = 1.29, 1.32, 1.36, 1.45 ppm (s0s, CH3);
31P{1H} NMR (CD2Cl2) d = 78.2 ppm; max(KBr)/cmꢁ1 904vs, 921vs,
m
2.1. General procedure
962vs
m(C–O–P), and 1114vs m(P@O); m
max(Nujol)/cmꢁ1, 391vs
m
(Pd–P).
Chemicals and deuterated solvents were purchased from Al-
drich and Fluka and used as received. All preparations were per-
formed in an atmosphere of dry, oxygen-free nitrogen, using
conventional Schlenk techniques. Solvents were carefully dried
and deoxygenated by standard methods [19]. The ligand precur-
sors: HP(OCMe2CMe2O)2 2,2,3,3,7,7,8,8-octamethyl-1,4,6,9-tetra-
oxa-5k5 phosphaspiro[4,4]nonane abbreviated as HPꢀO, HP-
2.2.3. [Pd(l-Cl){P(OCMe2CMe2O)OH}{P(OCMe2CMe2O)O}]2 (3)
The [PdCl2(cod)] (0.15 g, 0.52 mmol) was added to a solution of
HP(O)(OCMe2CMe2O) (0.19 g, 1.16 mmol) in toluene (5 cm3). The
reaction mixture was stirred vigorously for 6 h until the yellow
starting compound reacted and new white solid was afforded.
The crude product was filtered, washed with diethyl ether and
dried in vacuo (0.23 g, 93%). Single crystals suitable for X-ray anal-
ysis were obtained by re-crystallization from a dichloromethane/
ethyl ether solution.
(OCH2CMe2NH)2
3,3,8,8-tetramethyl-1,6-dioxa-4,9-diaza-5k5
phosphaspiro[4,4]nonane abbreviated as HPꢀN and HP(O)(OC-
Me2CMe2O), were prepared according to the literature method
[20–22]. [PdCl2(cod)], and [PdCl2P(OCH2CMe2NH)OCH2CMe2NH2]
(4) were synthesized as previously reported [23,21].
Anal. Calc. for C24H50Cl2O12P4Pd2: C, 30.72; H, 5.37; Found: C,
29.24; H, 5.26%; 1H NMR (CDCl3): d = 1.40 (s, CH3), 8.73 br (OH)
IR and FIR measurements were performed in KBr pellets either
with a Nicolet FTIR Impact 400 or in Nujol with a Bruker IFS 113 V.
1H, 31P{1H} NMR spectra were obtained on an Bruker Avance III
spectrometer (300 MHz for 1H NMR). Chemical shifts (d) are given
in ppm towards the TMS (1H) and H3PO4 (31P) using deuterated sol-
vents as lock and reference (1H), respectively. Elemental analyses
were performed on a Vario EL III apparatus. Analytical gas chro-
matographic (GC) analyses were performed on Hewlett–Packard
8452A fitted with a FID detector. Conversion of the substrates
was calculated using internal standard method. MS spectra were
measured on ESI Finnigan Mat TSQ 700 instrument.
ppm; 31P{1H} NMR (CDCl3) d = 83.9 ppm; max(Nujol)/cmꢁ1 874vs,
m
914vs, 955vs
m(C–O–P), 1135s m(P@O), 277w, 291vs, 269s, 307s,
m(Pd–P), (Pd–Cl).
m
2.3. Representative Heck reaction procedure
The Heck reactions were carried out in a 50 cm3 Schlenk tube
equipped with a magnetic stirrer under a nitrogen atmosphere.
In a typical experiment the flask was charged with the reagents:
catalyst (1.35 ꢂ 10ꢁ5 mol), bromobenzene PhBr 0.46 cm3
(4.36 ꢂ 10ꢁ3 mol), and n-butyl acrylate CH2@CHC(O)OBu
0.27 cm3 (1.9 ꢂ 10ꢁ3 mol) in DMF as a solvent (3 cm3) containing
mesitylene as internal standard. [nBu4N]Br 0.75 g (2.3 ꢂ 10ꢁ3 mol)
and base NaHCO3 0.37 g (4.4 ꢂ 10ꢁ3 mol) were used as additive.
The mixture was heated at 140 °C and stirred for 4 h. After that
time, the reaction mixture was cooled and organic products were
separated by extraction with diethyl ether (3 times with 7 cm3),
washed with water, dried over MgSO4 and analysed by GC–MS.
2.2. Syntheses of the complexes
2.2.1. [PdCl(l-Cl){P(OCMe2CMe2O)OCMe2CMe2OH}]2 (1)
The [PdCl2(cod)] (0.21 g, 0.73 mmol) was added to a solution of
HP(OCMe2CMe2O)2 (0.3 g, 1.1 mmol) in dichloromethane (5 cm3).
The yellow suspension was stirred for 20 min to produce yellow
solution. The crude product was precipitated with a hexane, fil-
tered, washed with hexane and dried in vacuo. Yield: 0.22 g, 68%.
From the mother liquor, a by-product complex 3, was isolated by
slow evaporation. (Yield 20%) Single crystals of 1 suitable for X-
ray analysis were obtained from an acetonitrile/ethyl ether
solution.
2.4. Crystal structure determinations
The data collection were performed with Mo Ka radiation on a
KM4CCD with a Sapphire camera for 1 and an Xcalibur PX with
Onyx camera for 3. Data reduction was carried out using the Ox-
ford Diffraction (Poland) programs. The structures were solved by
the Patterson method using SHELXS-97 and refined by the full-matrix
Anal. Calc. for C24H50Cl4O8P2Pd2: C, 32.64; H, 5.71. Found: C,
32.72; H, 5.65%; 1H NMR (CDCl3): d = 1.24, 1.38, 1.54, 1.91 ppm
(s0s, CH3); 31P{1H} NMR (CDCl3) d = 75.3 ppm;
m
max(Nujol)/cmꢁ1