Page 5 of 8
Dalton Transactions
DOI: 10.1039/D0DT00963F
1
II
crystals (41 mg, 71%). H NMR (500 MHz, C
6
D
6
, 298 K): δ =
plying that DMAP shields the Pt (Ph)2 unit from decom-
position.
5.76 (m, 4H; CH(allyl)), 4.90 (m, 4H; CH (allyl)), 4.84 (m, 4H;
2
CH
CH
2
2
(allyl)), 2.44 (m, 4H; P-CH
(allyl)), 1.27 (t, 6H, Pt-CH
2
CH
2
linker), 2.26 (m, 4H;
While the ultimate Pt–containing product(s) from the-
se thermolyses remains unknown, the observation of
3
2
17
3
; JP,H = 7.5 Hz, JPt,H = 70 Hz),
13
1
1.13 (m, 4H; CH
2
(allyl)). C{ H} NMR (125.8 MHz, C
6
D6, 298
CH4 (from 2), C6H6 (from 6), and cyclohexene (from 2 and
6) are consistent with the decomposition pathway pro-
posed in Scheme 5. Taken together, it is evident that
boron incorporation causes the thermolytic behaviour of 2
and 6 to differ from conventional e.g., dmpe- or dnppe-
substituted Pt bis-hydrocarbyl complexes (Scheme 4).
These reactions provide valuable insight regarding the
thermal stability of such Pt P2B 4 complexes; information
that will be taken into account for future work with this
ligand set.
We have shown that Pt P2B
readily accessed from Pt tetrakisallyl precursors via four-
fold hydroboration. These compounds offer a lens into the
reactivity of square-planar Pt
electrophilic secondary coordination spheres. In terms of
reactivity, these species readily bind strong Lewis bases
and when heated are more reactive (and show divergent
reactivity patterns) when compared to conventional alkyl-
substituted diphosphine Pt complexes – such reactivity is
suppressed in the presence of excess Lewis base (DMAP),
implicating involvement of the peripheral borane units.
K): δ = 132.33 (m), 117.34 (m), 31.05 (m), 24.45 (m), 0.14 (dd,
2
2
1
31
1
Pt-CH
NMR (202.5 MHz, C
3
;
J
P,C = 105 Hz, JP,C = 7.1 Hz,
J
Pt,C = 602 Hz). P{ H}
1
6
D
6
, 298 K): δ = + 39.7 ( JPt,P = 1727 Hz).
HRESI(+)-MS: (m/z) calcd. 505.1501 exptl. 505.1518 for
+
C
17
H
30NP
2
Pt [M-CH
3
+NCCH
(2; C64
the glovebox, Pt(tape)(CH
3
] .
122
II
II
Cy
Pt (P
2
B
4
)(CH
3
)
2
H
B
4
P
2
Pt, M
W
= 1192 g/mol): In
3
)
2
(24 mg, 0.05 mmol) and HBCy
2
II
Cy
(36 mg, 0.20 mmol, 4 equiv.) were added to a 20 mL scintilla-
tion vial equipped with a stir bar. Approximately 4 mL of
toluene was added and the solution was allowed to stir for 30
min at room temperature. The resulting pale yellow solution
II
Cy
4
complexes can be
II
®
was filtered through Celite and the solvent was removed in-
1
vacuo to give an off-white oil (58 mg, >98%). H NMR (500
II
MHz, C
6
D , 298 K): sδ = 1.91-1.08 (multiple overlapping
6
complexes having
3
3
2
C(sp )–H resonances), 1.17 (t, 6H, Pt-CH
3
; JP,H = 7.4 Hz, JPt,H
=
13
1
68 Hz). C{ H} NMR (125.8 MHz, C
6
D6, 298 K): δ = 36.10,
30.21, 27.99, 27.95, 27.51, 27.49, 26.98, 20.16, –0.16 (dd, Pt-CH
3
;
2
2
1
31
1
J
P,C = 102 Hz, JP,C = 6.7 Hz, JPt,C = 605 Hz). P{ H} NMR (202.5
1
11
1
MHz, C
(160.5 MHz, C
6
D
6
, 298 K): δ = + 44.3 ( JPt,P = 1756 Hz). B{ H} NMR
, 298 K): δ = + 82.9 (Δ1/2 = 1250 Hz).
II
6
D
6
HRESI(+)-MS: (m/z) calcd. 1217.9072 exptl. 1217.9111 for
+
C
65
H
122
B
4
NP
2
Pt [M-CH
)(DMAP)
3
+NCCH
(CH
g/mol): In the glovebox, Pt(P
3
] .
II
Cy
Pt (P
2
B
4
4
3
)
2
(3; C92
H
162
B
4
N
8
P
2
Pt, M
w
= 1680
EXPERIMENTAL
Cy
2
B
4
)(CH
3)2
(2) (25 mg, 0.02
mmol) and DMAP (10.2 mg, 0.08 mmol, 4 equiv.) were added
to a 20 mL scintillation vial equipped with a stir bar. Approx-
imately 4 mL of toluene was added and the solution was al-
lowed to stir for 20 min at room temperature. The resulting
General Considerations. All experiments were carried out
employing standard Schlenk techniques under an atmosphere
of dry nitrogen employing degassed, dried solvents in a sol-
vent purification system supplied by PPT, LLC. Non-
halogenated solvents were tested with a standard purple
solution of sodium benzophenone ketyl in tetrahydrofuran in
®
colorless solution was filtered through Celite and the solvent
1
was removed in-vacuo to give a colorless oil (31 mg, 88%). H
NMR (500 MHz, C
6
D
6
, 298 K): δ = 8.09 (br, 8H; DMAP|C-
order to confirm effective moisture removal. d
6
-benzene was
H
ortho), 5.99 (br, 8H; DMAP|C-Hmeta), 2.19 (s, 24 H;
3
dried over molecular sieves and degassed by three freeze-
DMAP|NMe ), 2.15-0.90 (overlapping C(sp )–H resonances),
2
18,
19
20
3
2
13
1
pump-thaw cycles. HBCy
2
tape, dnppe, and Pt(η4-
1.15 (t, 6H, Pt-CH
(125.8 MHz, C , 298 K): δ = 154.14 (DMAP), 145.54 (DMAP),
106.16 (DMAP), 38.38 (DMAP), 33.96, 31.58, 31.25, 30.50,
28.99, 26.69, 25.50, 22.67, -0.16 (dd, Pt-CH
6.8 Hz, JPt,C = 605 Hz). P{ H} NMR (202.5 MHz, C
3
; JP,H = 6.6 Hz, JPt,H = 66 Hz). C{ H} NMR
21
COD)Ph
2
were prepared according to a literature procedure.
6
D
6
All other reagents were purchased from commercial vendors
and used without further purification unless otherwise stat-
ed. Mass spectrometry was acquired using a Waters XEVO
G2-XS ToF.
2
2
3
; JP,C = 102 Hz, JP,C
=
1
31
1
6
D
6
, 298
1
11
1
K): δ = + 43.7 ( JPt,P = 1810 Hz). B{ H} NMR (160.5 MHz, C D ,
6
6
298 K): δ = + 4.21 (Δ1/2 = 200 Hz). ESI(+)-MS: (m/z) 1218 for
1
+
Physical methods. H NMR spectra are reported in parts per
C
65
H
122
B
4
NP
Pt (dnppe)(CH
glovebox, Pt(COD)(CH
2
Pt [M-CH
3
-8DMAP+NCCH
Pt, M
(40 mg, 0.12 mmol) and dnppe (31
3
] .
II
million (ppm) and are referenced to residual solvent:
3
)
2
(4; C16
H
38
P
2
W
= 487 g/mol): In the
1
13
H(C
6
D
6
): δ 7.16; C(C
6
D
6
): 128.06; coupling constants are
3)2
13
11
31
reported in Hz. C, B, and P NMR spectra were performed
as proton-decoupled experiments and are reported in ppm.
The multiplicities are abbreviated as follows: s = singlet, d =
doublet, dd = doublet of doublets, h = heptet (septet).
mg, 0.12 mmol, 1 equiv.) were combined in a 20 mL scintilla-
tion vial equipped with a stir bar. Approximately 4 mL of
THF was added and the solution was allowed to stir for 4 h at
room temperature. The resulting clear colorless solution was
®
filtered through Celite and the solvent was removed in-
o
Preparation of Compounds:
vacuo. Recrystallization from hexanes at –30 C gave colorless
II
1
Pt (tape)(CH
3
)
2
(1; C16
H
30
P
2
Pt, M
W
= 479 g/mol): In the
crystals (56 mg, 97%). H NMR (500 MHz, C
6
D6, 298 K): δ =
glovebox, Pt(COD)(CH
3
)
2
(40 mg, 0.12 mmol) and tape (31
1.56 (m, 8H), 1.41 (m, 4H), 1.28 (m, 4H), 1.20 (t, 6H, Pt-CH ;
JP,H = 7.5 Hz, JPt,H = 69 Hz), 1.06 (m, 4H), 0.87 (t, 12H, JH,H = 7.1
3
3
2
3
mg, 0.12 mmol, 1 equiv.) were combined in a 20 mL scintilla-
tion vial equipped with a stir bar. Approximately 4 mL of
THF was added and the solution was allowed to stir for 4 h at
room temperature. The resulting clear colorless solution was
13
1
Hz). C{ H} NMR (125.8 MHz, C
6
D
6
, 298 K): δ = 28.59 (m),
2
26.23 (m), 18.56 (m), 16.09 (m), -0.34 (dd, Pt-CH
P,C = 6.8 Hz, JPt,C = 601 Hz). P{ H} NMR (202.5 MHz, C
298 K): δ = + 44.7 ( JPt,P = 1768 Hz). HRESI(+)-MS: (m/z) calcd.
513.2122 exptl. 513.2122 for C17
3
; JP,C = 103 Hz,
2
1
31
1
J
6
D6,
®
1
filtered through Celite and the solvent was removed in-
o
+
vacuo. Recrystallization from hexanes at –30 C gave colorless
H
38NP
2
Pt [M-CH
3
+NCCH
3
] .