P.P. Phadnis et al. / Inorganica Chimica Acta 346 (2003) 119Á
/
128
121
product was recrystallised from acetoneÁ
ture as orange crystals in 70% (117 mg) yield. UVÁ
(CH2Cl2): lmax 420 (oꢀ
8240 Mꢁ1 cmꢁ1), 345sh (7800),
307 (26 010), 256 nm (24 770). Similarly [PtI2(B-
zAsMe2)2] was prepared from [PtCl2(BzAsMe2)2] (100
mg, 0.15 mmol) and a large excess of KI (598 mg, 3.60
/
hexane mix-
2.4.10. trans-[Pd2Cl2(m-dmpz)2(BzAsMe2)]
/Vis
To a stirred CH2Cl2 solution (25 cm3) of [Pd2Cl2(m-
OAc)2(BzAsMe2)] (68 mg, 0.086 mmol) a slight excess of
3,5-dimethylpyrazole (18 mg, 0.19 mmol) was added
under a nitrogen atmosphere and the whole was stirred
for 3 h. The solvent was evaporated under vacuum and
/
mmol) as orange crystals in 63% (80 mg) yield. UVÁ
(CH2Cl2): lmax 344 (oꢀ
6090 Mꢁ1 cmꢁ1), 288 nm (6900
Mꢁ1 cmꢁ1).
/
Vis
the residue was recrystallised from CH2Cl2Áhexane
mixture as pale yellow crystals in 70% (52 mg) yield.
13C{1H} in CDCl3: d 6.0, 7.9 (each s, AsMe2); 13.3, 13.6
/
/
(each s, Me2Ã
/
dmpz); 31.7 (s, AsCH2); 104.3 (s, dmpz C-
4); 126.9 (s, C-4); 128.8 (C-2, 6 or C-3, 5); 129.6 (s, C-3, 5
or C-2, 6); 134.7 (s, C-1) [Ph]; 147.2, 149.0 (each s, C-3, 5
dmpz).
2.4.6. [Pd2Cl2(m-Cl)2(BzAsMe2)2]
To a stirred benzene solution (50 cm3) of [PdCl2-
(BzAsMe2)2] (534 mg, 0.94 mmol), [PdCl2(MeCN)2] (235
mg, 0.91 mmol) was added and stirred for 1 h then
refluxed for 3 h. The solvent was evaporated and the
2.4.11. [Pd2Me2(m-dmpz)2(BzAsMe2)2]
To a stirred CH2Cl2 solution (30 cm3) of [Pd2Me(m-
Cl)2(BzAsMe2)2] (103 mg, 0.15 mmol) a slight excess of
methanolic solution (10 cm3) of dmpzH (30 mg, 0.31
mmol) containing aq. NaOH (0.66 cm3, 0.47 N, 12 mg,
0.30 mmol) was added under a nitrogen atmosphere.
The whole was stirred for 5 h and then filtered. The
solvent was evaporated in vacuo and the compound was
residue was recrystallised from benzeneÁhexane mixture
/
as orange red crystals in 71% (498 mg) yield. Similarly
[Pt2Cl2(m-Cl)2(BzAsMe2)2] was prepared from [PtCl2-
(BzAsMe2)2] (210 mg, 0.32 mmol) and PtCl2 (91 mg,
0.34 mmol), refluxing it in tetrachloroethane. The
residue was recrystallised from benzeneÁhexane mixture
in 34% (100 mg) yield.
/
recrystallised from CH2Cl2Á
coloured compound in 79% (95 mg) yield. 13C{1H} in
CDCl3: d ꢁ13.2 (s, PdMe); 7.0, 7.9 (each s, AsMe2);
13.7 (s, Me2Ãdmpz); 32.2 (s, AsCH2); 102.0 (s, C-4,
/hexane mixture as white
2.4.7. [Pd2Me2(m-Cl)2(BzAsMe2)2]
/
To an acetone solution (30 cm3) of [Pd2Cl2(m-
Cl)2(BzAsMe2)2] (253 mg, 0.34 mmol), a slight excess
of Me4Sn (130 mg, 0.73 mmol) was added under a
nitrogen atmosphere. Within a minute the colour faded.
The whole was stirred for 20 min. Then the solvent was
evaporated and the residue was washed with hexane to
remove Me3SnCl. The product was recrystallised from
/
dmpz); 126.3 (C-4); 128.5 (C-2, 6 or C-3, 5); 129.3 (C-3,
5 or C-2, 6); 135.8 (C-1) [Ph]; 145.4, 145.6 (each s, C-3, 5,
dmpz).
3. Results and discussion
acetoneÁhexane mixture as a cream crystalline solid in
/
66% (157 mg) yield.
3.1. Synthesis and spectroscopic analyses
2.4.8. [Pd2Cl2(m-OAc)2(BzAsMe2)2]
The syntheses of the palladium(II) and platinum(II)
complexes with benzyldimethylarsine are depicted in
Scheme 1 and their characterisation data are given in
To a stirred CH2Cl2 solution (25 cm3) of [Pd2Cl2(m-
Cl)2(BzAsMe2)2] (98 mg, 0.13 mmol), AgOAc (46 mg,
0.28 mmol) was added under a nitrogen atmosphere and
the whole was stirred for 4 h and the solvent was
evaporated and the product was recrystallised from
Tables 1 and 2. The reaction of [MCl2(RCN)2] (RꢀMe,
/
Ph) with 2 equiv. of BzAsMe2 readily gave [MCl2-
(BzAsMe2)2]. The chloride in the latter can be substi-
tuted with Br or I by treating it with an excess of KBr or
tolueneÁhexane mixture as red crystals in 54% (56 mg)
/
yield. 13C{1H} in CDCl3: d 6.6 (s, AsMe2); 23.4 (s, Me,
OAc); 31.9 (s, AsCH2); 127.2 (C-4); 129.0 (C-3, 5); 129.5
1
KI in acetone. The H NMR spectra exhibited singlets
each for the AsMe2 and AsCH2 protons which are
deshielded relative to the free ligand. The deshielding of
these resonances showed halogen dependence and
increases with increasing size of the halogen atom. The
signals for the platinum complexes were flanked by 195Pt
(C-2, 6); 133.4 (C-1) [Ph]; 182.2 (CÄ
/O).
2.4.9. [PdMe2(m-pz)2(BzAsMe2)]
To a stirred CH2Cl2 solution (30 cm3) of [Pd2Me2(m-
Cl)2(BzAsMe2)] (105 mg, 0.15 mmol), a methanolic
solution (10 cm3) of pyrazole (22 mg, 0.32 mmol)
containing aq. NaOH (0.65 cm3, 0.49 N, 13 mg, 0.32
mmol) was added under a nitrogen atmosphere. The
whole was stirred for 4 h and filtered. The solvent was
evaporated in vacuo and the residue was recrystallised
satellites. The 3J(PtÃ
approximately 17 Hz while the magnitude of J(PtÃ
associated with AsCH2 decreases with increasing the size
/
H) for the AsMe2 resonance is
3
/H)
3
of halogen atom J(PtÃ
/
H)ꢀ20 (Cl), 11 (Br), 7 (I) Hz).
/
The 195Pt NMR spectra display singlets (Table 2). The
195Pt NMR chemical shifts for [PtCl2(BzAsMe2)2] (d
from CH2Cl2Á
in 60% (69 mg) yield.
/
hexane mixture as a white cubic crystals
ꢁ
/
4320 ppm) can be compared with cis-[PtCl2(AsR3)2]
4363 ppm) [22,23]. The 195Pt
complexes (d ꢁ4287 to ꢁ
/
/