Organometallics
Article
CPh complexes,24 suggesting that the 2-indenylidene ligand
exerts a rather strong trans influence.
was evaporated to dryness and purified on a column of silica (i.d. = 16
mm, h = 80 mm). The column was first eluted with 60 mL of pentane
to remove the traces of CH3I. On a second elution, an orange-yellow
ring was recovered with CH2Cl2 as eluent. The solvent was eliminated
under vacuum to yield 3 as a pale orange solid (43 mg, 95%). Orange
crystals of 3 suitable for X-ray crystallography were obtained by slow
evaporation of a CH2Cl2 solution at room temperature. 31P{1H} NMR
(202 MHz, CD2Cl2): δppm 63.7 (d, JPP = 3.5 Hz), 60.1 (d, JPP = 3.5
Hz). 1H−NMR (500 MHz, CD2Cl2): δppm 7.94 (m, 2H, Hortho PPh2),
7.73 (m, 1H, Hpara PPh2), 7.67 (m, 2H, Hortho PPh2), 7.62 (m, 2H,
CONCLUSIONS
■
The chloropalladate pincer complex {PdCl[Ind(Ph2PS)2]}-
(nBu4N) (2) exhibits versatile reactivity. Noninnocent behavior
involving the electron-rich indenylidene backbone has been
evidenced toward organic electrophiles. Iodomethane and
benzyl chloride alkylate the C1 position to afford the
dissymmetric 2-indenyl complexes {PdI[Ind(Me)(Ph2P
S)2]} (3) and {PdCl[Ind(Bn)(Ph2PS)2]} (4), respectively.
In addition, dimethyl acetylenedicarboxylate inserts into the
C−P bond of one of the side arms to give the original complex
5, featuring three fused metallacycles. In contrast, nucleophiles
react at the Pd center of 2 and displace the chloride. PPh3 and
HNCy2 afford the neutral 2-indenylidene complexes {Pd-
(PPh3)[Ind(Ph2PS)2]} (6) and {Pd(NHCy2)[Ind(Ph2P
S)2]} (7), respectively, while PhCCLi gives the anionic 2-
indenylidene complex {Pd(CCPh)[Ind(Ph2PS)2]}-
(nBu4N) (8), the first alkynylpalladate to be isolated.
4
4
H
meta PPh2), 7.59 (m, 1H, Hpara PPh2), 7.57 (m, 1H, Hpara PPh2), 7.47
(m, 2H, Hmeta PPh2), 7.45 (m, 1H, Hpara PPh2), 7.33 (m, 2H, Hmeta
PPh2), 7.32 (m, 2H, Hmeta PPh2), 7.22 (m, 2H, Hortho PPh2), 7.19 (m,
2H, H6,7), 7.13 (m, 2H, Hortho PPh2), 7.11(m, 1H, H5), 6.74 (m, 1H,
3
H8), 1.91 (d, JPH = 18.5 Hz, 3H, Me). 13C{1H} NMR (125 MHz,
CD2Cl2): δppm 198.2 (dd, 2JCP = 28.4 and 10.5 Hz, C2), 145.3 (dd, 2JCP
= 8.9 Hz, 3JCP = 1.0 Hz, C9), 142.5 (dd, 2JCP = 18.9 Hz, 3JCP = 3.7 Hz,
C4), 141.2 (dd, 1JCP = 106.8 Hz, 3JCP = 9.1 Hz, C3), 133.3 (d, 4JCP = 3.0
4
2
Hz, Cpara PPh2), 132.8 (d, JCP = 3.0 Hz, Cpara PPh2), 132.7 (d, JCP
=
9.8 Hz, Cortho PPh2), 132.5 (d, 4JCP2 = 3.0 Hz, Cpara PPh2), 132.3 (d, 4JCP
= 3.0 Hz, Cpara PPh2), 132.1 (d, JCP = 9.0 Hz, Cortho PPh2), 131.7 (d,
2JCP = 11.5 Hz, Cortho PPh2), 130.9 (d, JCP = 11.5 Hz, Cortho PPh2),
2
3
3
128.8 (d, JCP = 12.1 Hz, Cmeta PPh2), 128.7 (d, JCP = 13.1 Hz, Cmeta
Future work will seek to modulate the ligand platform
(backbone and donor side arms) and to compare the reactivity
of the ensuing complexes with that of 2. In particular, these
studies will focus on systems that exhibit noninnocent behavior.
3
PPh2), 128.6 (d, JCP = 12.7 Hz, Cmeta PPh2), 128.3 (s, C5), 127.7 (d,
3JCP = 12.4 Hz, Cmeta PPh2), 127.0 (d, 1JCP = 80.0 Hz, Cipso PPh2), 126.9
1
4
(d, JCP = 80.0 Hz, Cipso PPh2), 124.4 (d, JCP = 1.6 Hz, C6 or 7), 123.4
1
1
(d, JCP = 68.6 Hz, Cipso PPh2), 122.7 (d, JCP = 81.5 Hz, Cipso PPh2),
122.5 (d, 4JCP = 1.6 Hz, C6 or 7), 118.9 (s, C8), 72.9 (dd, 1JCP = 52.9 Hz,
3JCP = 18.5 Hz, C1), 20.6 (br s, Me). HRMS (ESI-TOF): calcd for
C34H27PdP2S2 667.0064, found 667.0048 [M − I]; calcd for
C35H31OPdP2S2 699.0326, found 699.0295 [M − I + CH3OH].
Synthesis of {PdCl[Ind(Bn)(Ph2PS)2]} (4). A suspension of 2
(50 mg, 0.05 mmol) in 4 mL of neat benzyl chloride was heated for 2
h at 100 °C. After cooling, 10 mL of pentane was added to induce
precipitation. The whole crude mixture (solid and solution) was placed
on a column of silica (i.d. = 16 mm, h = 80 mm). The column was first
washed with a gradient of eluent (pentane to CH2Cl2) to remove all
traces of benzyl chloride. The yellow ring corresponding to 4 was
recovered with a CH2Cl2/Et2O mixture (90/10). The solvent was
eliminated under vacuum to yield a yellow solid (39 mg, 93%).
31P{1H} NMR (202 MHz, CDCl3): δppm 59.0 (d, 4JPP = 1.8 Hz), 50.7
EXPERIMENTAL SECTION
■
All reactions were performed using standard Schlenk techniques under
an argon atmosphere. 31P, 1H, and 13C spectra were recorded on
Bruker Avance 300 and 400 and AMX500 spectrometers. 31P, 1H, and
13C chemical shifts are expressed with a positive sign, in parts per
million, relative to external 85% H3PO4 and Me4Si. Unless otherwise
stated, NMR spectra were recorded at 293 K. Solvents were dried and
distilled prior to use (THF and toluene over sodium and pentane and
dichloromethane over CaH2). All organic reagents were obtained from
commercial sources and used as received. [Pd(PhCN)2Cl2] was
purchased from Strem. 1,3-Bis(diphenylphosphine)indene,25 1,3-
bis(diphenylthiophosphinoyl)indene,26 and complex 18b were pre-
pared according to literature procedures. The N values corresponding
4
1
(d, JPP = 1.8 Hz). H NMR (500 MHz, CDCl3): δppm 8.01 (m, 2H,
ortho PPh2), 7.73 (m, 1H, Hpara PPh2), 7.62 (m, 2H, Hmeta PPh2), 7.51
1
to /2(JAX + JAX′) are provided when second-order AXX′ systems are
observed in the 13C NMR spectra.27
H
(m, 1H, Hpara PPh2), 7.42 (m, 1H, Hpara PPh2), 7.34 (m, 3H, Hortho
PPh2, H Ind), 7.31 (m, 4H, Hortho,meta PPh2), 7.26 (m, 1H, Hpara PPh2),
7.19 (m, 3H, Hmeta PPh2, Hpara Bn), 7.06 (d, 2H, Hortho Bn), 7.02 (m,
2H, H Ind), 6.96 (m, 2H, Hmeta PPh2), 6.91 (t, 2H, Hmeta Bn), 6.84 (m,
Synthesis of {PdCl[Ind(Ph2PS)2]}(nBu4N) (2). A solution of 1
(670 mg, 1 mmol) and nBu4NCl (278 mg, 1 mmol) in 30 mL of
CH2Cl2 was added at −15 °C to a suspension of polystyrene-
supported diisopropylethylamine PS-DIEA (670 mg, 2 mmol) in 10
mL of CH2Cl2. After 1 h, the cold bath was removed, and the reaction
mixture was stirred for 1 h at room temperature. The reaction solution
was concentrated to one-fourth volume and filtered, and the PS-DIEA
was rinsed with CH2Cl2 (2 × 20 mL). The resulting orange solution
was then concentrated to the one-third volume, and 60 mL of pentane
was added slowly to induce precipitation. The suspension was stirred
for 1 h. The yellow solid was recovered by filtration, washed with
pentane (2 × 20 mL), and finally dried under vacuum at 40 °C
overnight. Compound 2 was obtained as a yellow powder (650 mg,
2H, Hortho PPh2), 6.25 (d, 1H, H Ind), 4.63 (dd, 2JH3H = 12.2 Hz, 3JPH
=
2
8.8 Hz, 1H, CH2 Ph), 3.09 (dd, JHH = 12.2 Hz, JPH = 5.6 Hz, 1H,
2
CH2 Ph). 13C{1H} NMR (125 MHz, CDCl3): δppm 187.8 (dd, JCP
=
2
3
24.7 and 6.6 Hz, C2), 145.4 (dd, JCP = 17.8 Hz, JCP = 4.1 Hz, C4),
144.7 (dd, 1JCP = 106.3 Hz, 3JCP = 8.4 Hz, C3), 143.3 (d, 3JCP = 9.3 Hz,
C9), 133.7 (d, 4JCP = 2.8 Hz, Cpara PPh2), 133.1 (d, 2JCP = 9.8 Hz, Cortho
2
PPh2), 133.0 (br, Cpara PPh2), 132.6 (d, JCP = 9.0 Hz, Cortho PPh2),
4
4
132.5 (d, JCP = 3.0 Hz, Cpara PPh2), 132.3 (d, JCP = 2.9 Hz, Cpara
PPh2), 131.7 (d, 2JCP = 11.7 Hz, Cortho PPh2), 131.4 (d, 2JCP = 11.4 Hz,
28
65%). 31P{1H} NMR (81 MHz, CD2Cl2): δppm 44.5 (s). H NMR
(300 MHz, CD2Cl2): δppm 7.84 (m, 8H, Hortho PPh2), 7.43 (m, 12H,
Hmeta, para PPh2), 7.01 (m, 2H, H6,7), 7.65 (m, 2H, H5,8), 3.21 (m, 8H,
N-CH2), 1.46 (m, 8H, N−CH2CH2), 1.27 (m, 8H, CH2CH3), 0.82 (t,
12H, CH2CH3). 13C{1H} NMR (75.5 MHz, CD2Cl2): δppm 165.9 (t,
1
C
ortho PPh2), 130.5 (s, Cortho PhCH2), 129.9 (s, Cipso PhCH2), 129.2 (d,
3
3JCP = 12.0 Hz, Cmeta PPh2), 128.8 (d, JCP = 13.1 Hz, Cmeta PPh2),
3
3
128.7 (s, C5), 128.6 (d, JCP = 12.9 Hz, Cmeta PPh2), 127.8 (d, JCP
=
1
12.5 Hz, Cmeta PPh2), 127.2 (d, JCP = 80.8 Hz, Cipso PPh2), 127.0 (d,
1JCP = 83.8 Hz, Cipso PPh2), 126.9 (s, Cmeta PhCH2), 126.1 (s, Cpara
PhCH2), 124.1 (d, 1JCP = 68.9 Hz, Cipso PPh2), 124.1 (d, 4JCP = 1.4 Hz,
C
C
2JCP = 29.4 Hz, C2), 137.2 (AA′XX′, N = 15.8 Hz, C4,9), 133.4 (d, 1JCP
=
1
4
6 or 7), 123.3 (d, JCP = 82.3 Hz, Cipso PPh2), 123.1 (d, JCP = 1.4 Hz,
81.8 Hz, Cipso PPh2), 131.4 (m, Cmeta PPh2), 130.7 (broad s, Cpara
PPh2), 127.9 (m, Cortho PPh2), 116.8 (s, C6,7), 115.4 (s, C5,8), 104.5
(AA′XX′, N = 74.0 Hz, C1,3), 58.5 (s, N-CH2), 23.6 (s, N−CH2CH2),
19.2 (s, CH2CH3), 13.0 (s, CH2CH3).
Synthesis of {PdI[Ind(Me)(Ph2PS)2]} (3). A solution of CH3I
(150 mg, 1 mmol) and 2 (50 mg, 0.05 mmol) in 4 mL of
dichloromethane was heated at 40 °C for 24 h. The reaction mixture
1
3
6 or 7), 118.3 (s, C8), 79.1 (dd, JCP = 50.4 Hz, JCP = 17.5 Hz, C1),
39.7 (s, CH2Ph). HRMS (ESI-TOF): calcd for C40H31PdP2S2
743.0377, found 743.0391 [M − Cl]; calcd for C42H34NPdP2S
784.0643, found 784.0642 [M − Cl + CH3CN].
Synthesis of Complex 5. An excess of DMAD (250 μL, 1.95
mmol) was added to a solution of 2 (150 mg, 0.15 mmol) in 20 mL of
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dx.doi.org/10.1021/om200706q|Organometallics 2011, 30, 6416−6422