76
R.A. Swanson et al. / Inorganica Chimica Acta 368 (2011) 74–83
(300 MHz) or an Inova (500 MHz) NMR spectrometer. 1H and
13C{1H} NMR chemical shifts are referenced to tetramethylsilane
(TMS) at 0.00 ppm. 31P{1H} NMR chemical shifts are referenced
to 85% H3PO4 at 0.0 ppm.
tained by dissolving ( )-4-Pt in CH2Cl2 and performing a diethyl
ether vapor diffusion. 1H NMR (CDCl3, 500 MHz) d 8.65 (dd, 2H,
e), 7.68 (dd, 4H), 7.45 (m, 8H), 7.32 (t, 4H), 7.15 (m, 10H), 6.79 (t,
4H), 6.68 (dd, 4H), 6.49 (d, 2H), 6.38 (dd, 2H). 13C{1H} NMR (CDCl3,
126 MHz) d 165.2 (m), 143.0 (s), 142.2 (m), 136.2 (m), 133.0 (m),
132.3 (m), 131.9 (s), 131.5 (m), 131.4 (s), 130.1 (s), 128.7 (m),
128.4 (m), 127.8 (s), 127.5 (m), 127.2 (s), 127.0 (m), 126.7 (m),
126.2 (m), 125.7 (s), 66.0 (s). 31P{1H} NMR (CDCl3, 202 MHz) d
4.1 (1JP–Pt = 3120 Hz).
2.2. Syntheses
2.2.1. Synthesis of (R,R)-2-Pt
To a 25 mL flask were added (R,R)-2 (0.150 g, 0.217 mmol) and
Pt(COD)Cl2 (0.0815 g, 0.218 mmol) dissolved in THF (10 mL). NaH
(0.0203 g, 0.508 mmol, 60% in oil) was weighed into a 50 mL side
arm flask and THF (10 mL) was added. The solution containing
the ligand and Pt(COD)Cl2 was transferred via cannula to the flask
containing the NaH. The yellow solution was heated at 50 °C. The
solution continued to stir for 24 h. After this time a white solid
had precipitated out of solution. The solution was inverse filtered
to yield (R,R)-2-Pt (0.068 g, 0.077 mmol) in 35% yield. X-ray crys-
tals were obtained by dissolving (R,R)-2-Pt in CH2Cl2 and perform-
ing a diethyl ether vapor diffusion. 1H NMR (CDCl3, 500 MHz)
d 8.47 (dd, 2H), 7.48 (t, 2H), 7.35 (m, 4H), 7. 26 (dd, 4H), 7.18 (m,
6H), 7.13 (m, 4H), 7.08 (m, 4H), 6.67 (dd, 2H), 3.69 (m, 2H), 2.65
(br d, 2H), 1.61 (m, 2H), 1.54 (br q, 2H), 1.31 (br t, 2H). 13C{1H}
NMR (CDCl3, 126 MHz) d 167.7 (m), 144.8 (m), 133.6 (m), 133.5
(m), 131.9 (m), 131.6 (s), 131.3 (m), 131.1 (s), 130.8 (s), 129.4
(m), 128.8 (m), 128.7 (m), 128.4 (m), 125.6 (m), 125.1 (m), 68.0
2.3. Reaction of (R,R)-2-Pt with HCl
In an NMR tube, 22 mg of (R,R)-2-Pt was dissolved in CDCl3
(previously de-oxygenated). Both 1H and 31P{1H} NMR analyses
was performed on the sample to ensure it was pure then excess
HCl was bubbled through the solution for 1 min. The HCl was pre-
pared via the reaction of conc. H2SO4 with NaCl in a test tube
equipped with a N2 inlet stream to push the HCl formed through
to a dry ice/acetone trap and finally to a needle that was immersed
in the NMR sample. After the addition, the NMR tube was shaken
by hand for 2 min and then 1H and 31P{1H} NMR spectra were re-
corded immediately. The NMR corresponded to those for (R,R)-2-
PtCl2 reported below.
2.4. Isolation of (R,R)-2-PtCl2
(s), 31.5 (s), 26.4 (s). 31P{1H} NMR (CDCl3, 202 MHz) d 5.4 (1JP–Pt
=
3150 Hz).
To a 10 mL round bottom flask was added Pt(COD)Cl2 (5.2 mg,
1.4 ꢁ 10ꢂ5 mol) and (R,R)-2 (9.6 mg, 1.4 ꢁ 10ꢂ5 mol) and CHCl3
(5 mL). The solution was stirred under N2 for 16 h then solvent
was removed under vacuum. The residue was dissolved in minimal
CH2Cl2 and crystallized via vapor diffusion of Et2O into the solu-
tion. A single crystal of (R,R)-2-PtCl2 was analyzed by X-ray diffrac-
tion and the crystal was then analyzed by 1H and 31P{1H} NMR. The
remaining unused solid (8.1 mg, 8.5 ꢁ 10ꢂ6 mol, 61%) was also
analyzed by 1H NMR and was shown to be the same as the crystal.
1H NMR (CDCl3, 500 MHz) d 7.97 (m, 4H), 7.78 (d, 1H), 7.40 (m,
11H), 7.22 (m, 5H), 7.08 (m, 2H), 7.01 (dd, 1H), 6.94 (m, 1H),
6.85 (m, 3H), 4.53 (m, 1H), 3.22 (m, 1H), 2.72 (br d, 1H), 2.60 (br
q, 1H), 1.93 (br d, 1H), 1.86 (br d, 1H), 1.64 (m, 1H), 1.46 (m, 1H),
1.31 (m, 1H), 0.82 (br q, 1H). 31P{1H} NMR (CDCl3, 202 MHz) d
11.1 (1JP–Pt = 3880 Hz, 1P), 7.2 (1JP–Pt = 3680 Hz, 1P).
2.2.2. Synthesis of (R,R)-3-Pt
In a glove box, (R,R)-3 (0.299 g, 0.378 mmol) and NaOMe
(0.085 g, 1.57 mmol) were dissolved in THF (6 mL) in a 20 mL sam-
ple vial. In a separate vial, Pt(COD)Cl2 (0.141 g, 0.377 mmol) was
dissolved in THF (5 mL). The solutions were stirred for 10 min then
the mixture of (R,R)-3 and NaOMe was added to the platinum com-
plex solution. The resulting solution was stirred for 2 h. The solu-
tion was transferred to a 50 mL sidearm flask, removed from the
glove box, and placed on a Schlenk line. The stirred solution was
refluxed for 14 h. No significant precipitate was noted after this
time. The solvent was removed under vacuum and the residue
was re-dissolved in minimal methylene chloride, filtered through
a Celite plug, and the solvent was again removed under vacuum.
The resulting crude product was loaded onto a Biotage Isolera
automated column system and purified by running 12 column vol-
umes in a 1:1 ethyl acetate:hexanes and then changing gradient to
2:1 ethyl acetate:hexanes. The pure product (R,R)-3-Pt was isolated
in 5.3% yield (0.0198 g, 0.0201 mmol). 1H NMR (CDCl3): d = 8.45 (br
d, 2H), 7.75 (m, 4H), 7.63 (br d, 2H), 7.44–7.48 (m, 6H), 7.29 (m,
2H), 7.24 (m, 4H), 7.20 (m, 2H), 6.89 (br s, 8H), 6.37 (br t, 2H),
3.70 (m, 2H), 3.36 (br d, 2H), 1.70 (m, 2H), 1.48 (br t, 2H), 1.22
(m, 2H). 13C{1H} NMR (CDCl3, 126 MHz) d 176.7 (m), 146.8 (m),
135.9 (t), 135.2 (s), 133.4 (t), 131.9 (s), 131.1 (m), 130.7 (s), 128.7
(t), 128.5 (t), 128.3 (m), 128.1 (s), 128.0 (s), 127.9 (s), 127.5 (s),
125.9 (m), 68.7 (s), 31.4 (s), 26.2 (s). 31P{1H} NMR (CDCl3,
202 MHz) d 2.1 (1JP–Pt = 3130 Hz).
2.5. X-ray crystallography
The crystal data for (R,R)-2-Pt, (R,R)-3-Pt, ( )-4-Pt, and (R,R)-2-
PtCl2 are collected in Table 1. Crystals of (R,R)-2-Pt, (R,R)-3-Pt,
( )-4-Pt, and (R,R)-2-PtCl2 suitable for X-ray structure determina-
tion were obtained by vapor diffusion of diethyl ether into a con-
centrated solution of the compound of interest in CH2Cl2. Data
were collected on a Bruker X8 APEX ((R,R)-2-Pt and ( )-4-Pt) or a
Bruker Apex II ((R,R)-3-Pt and (R,R)-2-PtCl2) diffractometer with
graphite monochromated Mo Ka radiation at 173 K or 100 K (Table
1). The data were integrated using the Bruker SAINT ((R,R)-2-Pt and
( )-4-Pt) [17] or SHELXTL ((R,R)-3-Pt and (R,R)-2-PtCl2) [18] software
programs and the structures were solved by direct methods [19].
All refinements were performed using the SHELXTL [20] crystallo-
graphic software package of Bruker-AXS. Neutral atom scattering
factors were taken from Cromer and Waber [21]. Anomalous dis-
2.2.3. Synthesis of ( )-4-Pt
To a 100 mL flask were added ( )-4 (0.1503 g, 0.1896 mmol)
and Pt(COD)Cl2 (0.0715 g, 0.191 mmol) dissolved in THF (7 mL).
NaH (0.0167 g, 0.418 mmol, 60% in oil) was weighed into a
100 mL side arm flask and THF (10 mL) was added. The solution
containing the ligand and Pt(COD)Cl2 was transferred via cannula
to the flask containing the NaH. The yellow solution was heated
at 50 °C. After one hour of heating the solid had gone into solution.
The solution continued to stir for ꢀ17 h. After this time a brown-
pink solid precipitated. The solution was inverse filtered to yield
( )-4-Pt (0.062 g, 0.063 mmol) in 33% yield. X-ray crystals were ob-
persion effects were included in Fcalc [22]; the values for
D
D
f0 and
f00 were those of Creagh and McAuley [23]. The values for the
mass attenuation coefficients are those of Creagh and Hubbell
[24]. Further details specific to each analysis are given below.
2.5.1. (R,R)-2-Pt
A colorless prism crystal of C44H38N2O2P2Pt having approximate
dimensions of 0.12 ꢁ 0.12 ꢁ 0.25 mm was mounted on a glass