Crystal Structure of [Pt{CH2C(O)Me}2(bpy)]
Organometallics, Vol. 17, No. 8, 1998 1565
ods. [PdCl2(tmeda)] (tmeda ) N,N,N′,N′-tetramethylethyl-
enediamine) was prepared by refluxing an acetone (20 mL)
suspension of PdCl2 (0.79 g, 4.47 mmol) and tmeda (0.52 g,
4.47 mmol) for 3 h. After the resulting suspension was stirred
overnight, it was filtered and the solid washed with acetone
and diethyl ether to give [PdCl2(tmeda)] (1.25 g, 95%) as a
yellow solid.
Syn th esis of [P d {CH2C(O)Me}Cl(tm ed a )] (1). [PdCl2-
(tmeda)] (200 mg, 0.68 mmol) and Ag2O (157 mg, 0.68 mmol)
were refluxed in acetone (20 mL) for 3 h. The resulting
suspension was filtered through Celite, the solution concen-
trated to dryness, and the residue treated with dichlo-
romethane (15 mL). The mixture was allowed to settle in the
refrigerator for 1 h and filtered through Celite. The clear
yellow solution was concentrated (to ca. 2 mL), and diethyl
ether (20 mL) was added to precipitate 1 as a yellow solid.
Yield: 180 mg, 84%. Mp: 150 °C (decomp). Anal. Calcd for
C9H21ClN2OPd: C, 34.30; H, 6.72; N, 8.89. Found: C, 34.45;
H, 6.67; N, 8.46. 1H NMR: δ 2.26 (s, 2H, PdCH2), 2.56 (s, 3H,
MeCO), 2.64 (s, 6H, NMe2), 2.69 (s, 6H, NMe2), 2.5-2.8 (m,
CH2N). 13C{1H} NMR: δ 24.54 (PdCH2), 30.74 (MeC(O)), 48.81
(NMe2), 49.99 (NMe2), 58.36 (NCH2), 63.94 (NCH2), 213.58
(CO). IR (cm-1): ν(CO), 1632 (s); ν(PdCl), 318 (m).
Syn th esis of [P t{CH2C(O)Me}Cl(bp y)] (2). Bpy (2,2′-
bipyridine, 36 mg, 0.229 mmol) and chloroacetone (0.06 mL,
0.72 mmol) were successively added to a suspension of [Pt-
(dba)2] (dba ) dibenzylideneacetone, 150 mg, 0.226 mmol) in
acetone under a nitrogen atmosphere. The resulting suspen-
sion was stirred at room temperature for 3.5 h and concen-
trated to dryness. The residue was extracted with dichlo-
romethane (3 × 20 mL), and the combined extracts were
filtered through anhydrous MgSO4. The solution was concen-
trated to ca. 2 mL, and diethyl ether (20 mL) was added to
precipitate 2 as a yellow solid. Yield: 43 mg, 43%. Mp: 230
°C (decomp). Anal. Calcd for C13H13ClN2OPt: C, 35.18; H,
2.95; N, 6.31. Found: C, 34.89; H, 2.88; N, 6.18. 1H NMR: δ
2.29 (s, 3H, Me, 4J HPt ) 12.7 Hz), 3.39 (s, 2H, CH2, 2J HPt ) 109
Hz), 7.9-7.99 (m, 2H), 8.47-8.68 (m, 4H), 9.46-9.65 (m, 2H).
13C{1H} NMR: not soluble enough. IR (cm-1): ν(CO), 1636
(s); ν(PtCl), 338 (m).
2 was also obtained (50% yield) when a mixture of equimolar
amounts (ca. 0.5 mmol) of [PtCl2(bpy)] and KOH was refluxed
in acetone (20 mL) for 36 h. The resulting suspension was
concentrated to dryness, the residue extracted with dichlo-
romethane (3 × 20 mL) and filtered through anhydrous
MgSO4, the solution concentrated to ca.1 mL, and diethyl ether
(20 mL) added.
The reactivity of acetonyl complexes is almost unex-
plored. Insertion of isocyanides into the Pd-C bond of
trans-[Pd{CH2C(O)Me}Cl(PPh3)2] has been reported to
produce â-ketoenamine ligands σ-bonded to palladium.17
A similar behavior has been found in the corresponding
PhC(O)CH2 derivative.26 Other ketonylpalladium com-
plexes have been reacted with CO, ethylene, and buta-
diene to lead to C-C bond formation at the R-carbon of
the starting ketones.27 Treatment of [Pd{CH2C(O)-
But}Br(PPh3)2] with ButOK lead to the ylide Ph3PdCHC-
(O)But.28
The few acetonyl complexes characterized by X-ray
diffraction methods are of Mn,29 Co,30-32 Au,8,9,33 Rh,34
Hg,35,36 and Tl.6,9 No crystal structure of any acetonyl
Pd or Pt complex is available so far. The only reported
CH2C(O)R derivatives of Pd(II) or Pt(II) are trans-[Pd-
{CH2C(O)Ph}Cl(PPh3)2] and cis-[Pd2{µ-CH2C(O)Ph}2-
(PPh3)4].26 31P NMR data conclusively prove that while
in the case of platinum cis-[Pt{CH2C(O)Me}Cl(PR3)] and
both cis- and trans-[Pt{CH2C(O)Me}R′(PR3)2]15,18 (R′ )
Me, Ph) complexes can be prepared, only the trans-[Pd-
{CH2C(O)Me}Cl(PR3)2]18 isomers have been isolated in
the case of palladium, which is in accordance with the
known tendency of phosphines to avoid coordinating
trans to carbon-donor ligands in palladium complexes
(transphobia).37
Here, we describe some new ketonyl and ketimine
complexes including the first acetonyl complexes of Pd-
(II) and Pt(II) with nitrogen-donor ligands, the first
diacetonyl Pt(II) complex, and the first crystal structure
of an acetonylplatinum complex.
Exp er im en ta l Section
All of the reactions were carried out in normal laboratory
conditions. Technical-grade solvents were purified by stan-
dard procedures. Conductivities were measured on ca. 5 ×
10-4 M acetone solutions. Melting points are uncorrected.
Unless otherwise stated, NMR spectra were measured in
CDCl3 on a Varian Unity 300 spectrometer at room temper-
ature. Chemical shifts (in ppm) are referenced to TMS (1H
and 13C{1H}). Mass spectra (FAB) were measured using
3-nitrobenzyl alcohol as the dispersing matrix. Complexes [Pt-
(dba)2]38 and [PtCl2(bpy)]39 were prepared by literature meth-
Syn th eses of [P t{CH2C(O)R}2(bp y)] (R ) Me (3), Et (4)).
Complexes 3 and 4 were prepared by refluxing [PtCl2(bpy)]
(ca. 0.5 mmol) with an excess of NaOH (molar ratio 1:15) in
acetone (20 mL) (3) or methylethyl ketone (15 mL) (4) for 4 h.
The reaction mixtures were concentrated to dryness, the
residues extracted with dichloromethane (3 × 20 mL), and the
extracts filtered through anhydrous MgSO4. The solutions
were concentrated to ca. 1 mL, and diethyl ether (20 mL) was
added to precipitate the complexes as orange (3) and yellow
(4) solids. 3: yield, 64%. Mp: 150 °C (decomp.). Anal. Calcd
for C16H18N2O2Pt: C, 41.29; H, 3.90; N, 6.02. Found: C, 41.11;
H, 3.89; N, 6.10. 1H NMR (200 MHz): δ 2.23 (s, 6H, Me, 3J HPt
) 19 Hz), 3.26 (s, 4H, CH2, 2J HPt ) 120 Hz), 7.57 (m, 2H), 7.99
(m, 4H), 9.96 (m, 2H). 13C{1H} NMR: δ 21.94 (Me), 30.37
(CH2), 122.04 (C5, C6), 126.93 (C3, C8), 137.61 (C4, C7), 150.49
(C2, C9) 155.95 (Cipso), 215.26 (s, CO). IR (cm-1): ν(CO), 1648
(s). MS (FAB+): m/z 465 (M+, 13.3), 448 (M+ - Me, 16), 408
(100, M+ - CH2C(O)Me), 365 (Pt(bpy)CH2, 17.5), 351 (Pt(bpy),
49.4). 4: yield, 56%. Mp: 210 °C (decomp). Anal. Calcd for
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C
18H22N2O2Pt: C, 43.81; H, 4.49; N, 5.68. Found: C, 43.76;
3
H, 4.41; N, 5.77. 1H NMR (200 MHz): δ 1.06 (t, Me, 6H, J HH
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