Palladium(II) terminal phosphido complexes derived from cyclometalated dimesitylphosphine: Synthesis, structure, and low-barrier phosphorus inversion

Article abstract of DOI:10.1021/om020249k

The cyclometalated cationic Pd(II) and Pt(II) complexes [M(diphos)(CH₂C₆H₂Me₂P(Mes)-(H))] [X] (5-8: M = Pd, Pt; diphos = dppe (Ph₂PCH₂CH₂PPh₂), dppen (cis-Ph₂PCH=CHPPh₂); Mes = 2,4,6-Me₃C₆H₂; X = OTf, BF₄) were prepared by thermolysis of the cations [M(diphos)-(Me)(PMes₂H)] [X]. Deprotonation of 5-8 gave the neutral phosphido complexes M(diphos)-(CH₂C₆H₂Me₂P(Mes)) (9-12); the Pd(II) compounds 9 and 11 are the first examples of stable palladium terminal phosphido alkyl complexes, and their crystal structures were determined. Fluxional processes in complexes 9-12 were studied by variable-temperature NMR spectroscopy; the spectra are consistent with low barriers to phosphorus inversion.

Full text of DOI:10.1021/om020249k

3208
Organometallics 2002, 21, 3208-3214
P a lla d iu m (II) Ter m in a l P h osp h id o Com p lexes Der ived
fr om Cyclom eta la ted Dim esitylp h osp h in e: Syn th esis,
Str u ctu r e, a n d Low -Ba r r ier P h osp h or u s In ver sion
Michael A. Zhuravel and David S. Glueck*
6128 Burke Laboratory, Department of Chemistry, Dartmouth College,
Hanover, New Hampshire 03755
Lev N. Zakharov and Arnold L. Rheingold
Department of Chemistry, University of Delaware, Newark, Delaware 19716
Received April 1, 2002
The cyclometalated cationic Pd(II) and Pt(II) complexes [M(diphos)(CH2C6H2Me2P(Mes)-
(H))][X] (5-8: M ) Pd, Pt; diphos ) dppe (Ph2PCH2CH2PPh2), dppen (cis-Ph2PCHdCHPPh2);
Mes ) 2,4,6-Me3C6H2; X ) OTf, BF4) were prepared by thermolysis of the cations [M(diphos)-
(Me)(PMes2H)][X]. Deprotonation of 5-8 gave the neutral phosphido complexes M(diphos)-
(CH2C6H2Me2P(Mes)) (9-12); the Pd(II) compounds 9 and 11 are the first examples of stable
palladium terminal phosphido alkyl complexes, and their crystal structures were determined.
Fluxional processes in complexes 9-12 were studied by variable-temperature NMR
spectroscopy; the spectra are consistent with low barriers to phosphorus inversion.
In tr od u ction
(t-Bu)3C6H2) in solution, but they decomposed by reduc-
tive elimination below room temperature.3g,6 Here we
report the synthesis and structure of thermally stable
Pd terminal phosphido complexes derived from cyclo-
metalated dimesitylphosphine. Low barriers to inver-
sion at the phosphido P were established for these and
analogous Pt complexes by variable-temperature NMR
studies.
Terminal phosphido complexes of Ni, Pd, and Pt are
important intermediates in metal-catalyzed hydrophos-
phination1 and phosphination reactions.2 Although sev-
eral Pt and a few Ni complexes with terminal phosphido
ligands have been structurally characterized,3,4 ana-
logous Pd complexes have been elusive.5 We generated
Pd phosphido alkyl complexes such as Pd(dppe)(Me)-
(PHMes*) (dppe ) Ph2PCH2CH2PPh2, Mes* ) 2,4,6-
Resu lts a n d Discu ssion
* To whom correspondence should be addressed. E-mail: Glueck@
Dartmouth.Edu.
The complexes [Pd(dppen)(Me)(PMes2H)][OTf] (1;
dppen ) cis-Ph2PCHdCHPPh2, Mes ) 2,4,6-Me3C6H2)
and [Pt(dppen)(Me)(PMes2H)][OTf] (2) were prepared by
treatment of M(dppen)(Me)(Cl) (M ) Pd, Pt) with AgOTf
and PMes2H in THF in the presence of MeCN (Scheme
1). The complexes were isolated in good yields as white
crystalline solids and characterized by NMR and IR
spectroscopy (Table 1) and elemental analysis. The
(1) Wicht, D. K.; Glueck, D. S. In Catalytic Heterofunctionaliza-
tion: From Hydroamination to Hydrozirconation; Togni, A., Grutzma-
cher, H., Eds.; Wiley-VCH: Weinheim, Germany, 2001; pp 143-170.
(2) For selected examples of catalytic phosphination, see: (a) Lucht,
B. L.; St. Onge, N. O. Chem. Commun. 2000, 2097-2098. (b) Cai, D.;
Payack, J . F.; Bender, D. R.; Hughes, D. L.; Verhoeven, T. R.; Reider,
P. J . Org. Synth. 1999, 76, 6-11. (c) Herd, O.; Hessler, A.; Hingst, M.;
Machnitzki, P.; Tepper, M.; Stelzer, O. Catal. Today 1998, 42, 413-
420. (d) Tunney, S. E.; Stille, J . K. J . Org. Chem. 1987, 52, 748-753.
(3) For Pt terminal phosphido complexes, see: (a) Kovacik, I.; Wicht,
D. K.; Grewal, N. S.; Glueck, D. S.; Incarvito, C. D.; Guzei, I. A.;
Rheingold, A. L. Organometallics 2000, 19, 950-953. (b) Wicht, D. K.;
Kourkine, I. V.; Kovacik, I.; Glueck, D. S.; Concolino, T. E.; Yap, G. P.
A.; Incarvito, C. D.; Rheingold, A. L. Organometallics 1999, 18, 5381-
5394. (c) Wicht, D. K.; Glueck, D. S.; Liable-Sands, L. M.; Rheingold,
A. L. Organometallics 1999, 18, 5130-5140. (d) Wicht, D. K.; Kovacik,
I.; Glueck, D. S.; Liable-Sands, L. M.; Incarvito, C. D.; Rheingold, A.
L. Organometallics 1999, 18, 5141-5151. (e) Kourkine, I. V.; Sargent,
M. D.; Glueck, D. S. Organometallics 1998, 17, 125-127. (f) Wicht, D.
K.; Paisner, S. N.; Lew, B. M.; Glueck, D. S.; Yap, G. P. A.; Liable-
Sands, L. M.; Rheingold, A. L.; Haar, C. M.; Nolan, S. P. Organome-
tallics 1998, 17, 652-660. (g) Wicht, D. K.; Kourkine, I. V.; Lew, B.
M.; Nthenge, J . M.; Glueck, D. S. J . Am. Chem. Soc. 1997, 119, 5039-
5040. (h) Cecconi, F.; Ghilardi, C. A.; Midollini, S.; Moneti, S.;
Orlandini, A.; Scapacci, G. Inorg. Chim. Acta 1991, 189, 105-110. (i)
Handler, A.; Peringer, P.; Muller, E. P. J . Chem. Soc., Dalton Trans.
1990, 3725-3727. (j) Maassarani, F.; Davidson, M. F.; Wehman-
Ooyevaar, I. C. M.; Grove, D. M.; van Koten, M. A.; Smeets, W. J . J .;
Spek, A. L.; van Koten, G. Inorg. Chim. Acta 1995, 235, 327-338. (k)
Schaefer, H.; Binder, D. Z. Anorg. Allg. Chem. 1988, 560, 65-79. (l)
Allen, C. W.; Ebsworth, E. A. V.; Henderson, S. G.; Rankin, D. W. H.;
Robertson, H. E.; Turner, B.; Whitelock, J . D. J . Chem. Soc., Dalton
Trans. 1986, 1333-1338.
(4) For Ni terminal phosphido complexes, see: (a) Schaefer, H.;
Binder, D.; Deppisch, B.; Mattern, G. Z. Anorg. Allg. Chem. 1987, 546,
79-98. (b) Schaefer, H. Z. Anorg. Allg. Chem. 1979, 459, 157-169. (c)
Driess, M.; Pritzkow, H.; Winkler, U. J . Organomet. Chem. 1997, 529,
313-321. (d) Melenkivitz, R.; Mindiola, D. J .; Hillhouse, G. L. J . Am.
Chem. Soc. 2002, 124, 3846-3847.
(5) For Pd bridging phosphido complexes, see: (a) Leoni, P.; Mar-
chetti, P.; Papucci, S.; Pasquali, M. J . Organomet. Chem. 2000, 593-
594, 12-18. (b) Zhuravel, M. A.; Moncarz, J . R.; Glueck, D. S.; Lam,
K.-C.; Rheingold, A. L. Organometallics 2000, 19, 3447-3454. (c)
Review: Mealli, C.; Ienco, A.; Galindo, A.; Carren˜o, E. P. Inorg. Chem.
1999, 38, 4620-4625. (d) See also: Belykh, L. B.; Cherenkova, T. V.;
Shmidt, F. K. Russ. J . Coord. Chem. (Engl. Transl.) 1999, 25, 418-
422. (e) For Pd diphosphaureylene complexes (formally, terminal
phosphido complexes, with the chelating Mes*PC(O)PMes* ligand;
Mes* ) 2, 4, 6-(t-Bu)3C6H2), see: David, M.-A.; Wicht, D. K.; Glueck,
D. S.; Yap, G. P. A.; Liable-Sands, L. M.; Rheingold, A. L. Organome-
tallics 1997, 16, 4768-4770.
(6) (a) Zhuravel, M. A. Ph.D. Thesis, Dartmouth College, 2000. (b)
Zhuravel, M. A.; Wicht, D. K.; Sweeder, R. D.; Moncarz, J . R.; Glueck,
D. S.; Lam, K.-C.; Yap, G. P. A., Incarvito, C. D.; Sommer, R.;
Rheingold, A. L. Manuscript in preparation.
10.1021/om020249k CCC: $22.00 © 2002 American Chemical Society
Publication on Web 06/19/2002

Palladium(II) Terminal Phosphido Complexes
Organometallics, Vol. 21, No. 15, 2002 3209
Ta ble 1. 31P NMR a n d Selected 1H NMR a n d IR Da ta for Ca tion ic Com p lexes 1-8a
compd
δ(P1) (J PtP
)
δ(P2) (J PtP
)
δ(P3) (J PtP
-47.6
)
J 13
J 12
J 23
δ(PH)
1J PH
νPH
1
2
3
4
5
6
7
8
64.6
59.1 (2852)
59.5
54.9 (2846)
56.9
61.5 (2757)
54.7
54.4
55.9 (1711)
42.7
49.6 (1692)
50.7
59.3 (1786)
43.8
373
387
367
379
344
358
339
352
12
8
33
4
16
8
29
7
33
16
26
17
29
13
30
15
6.61
6.95
6.52
7.01
b
6.51
6.53
b
360
366
357
378
b
2389
2372
2318
b
2384
2391
2381
2390
-50.0 (2597)
-47.2
-42.8 (2553)
-19.7
-16.7 (2681)
-14.8
b
364
50.1 (2767)
44.2 (1788)
-17.7 (2632)
362c
a
Legend and conditions: M ) Pd (1, 3, 5, 7), Pt (2, 4, 6, 8); diphos ) dppen (1, 2, 5, 6), dppe (3, 4, 7, 8); solvent CD2Cl2; 31P NMR
chemical shift reference external H3PO4 (85%); coupling constants in Hz. Not observed. c From the 31P NMR spectrum.
b
Ta ble 2. 31P NMR Da ta for Ter m in a l P h osp h id o
Sch em e 1
Com p lexes 9-12a
compd δ(P1) (J PtP
)
δ(P2) (J PtP
)
δ(P3) (J PtP
)
J 13 J 12 J 23
9
10
11
12
47.3
47.0
30.5
124
3
7
b
8
b
56.9 (1895) 58.0 (1935) 10.6 (1102) 140 13
36.4 34.4 24.7 124 21
47.9 (1922) 45.9 (1933) 8.8 (1112) 143
b
a
Conditions: solvent toluene-d8; 31P NMR chemical shift refer-
b
ence external H3PO4 (85%); coupling constants in Hz. Not
observed.
pared and deprotonated the analogous BF4 salts of 5-8
(see the Experimental section). The less soluble NaBF4
could be separated from 9-12 by recrystallization. The
31P NMR spectra of salt-free 9-12 were identical with
those of samples which contained triflate or BF4 salts.
As previously observed for terminal Pt and Pd phos-
phido complexes, 9-12 display reduced trans J PP and
J PtP values (Table 2) in comparison to cationic precur-
sors 5-8.3,5
We reported previously that the terminal phosphido
alkyl complex Pd(dppe)(Me)(PHMes*) decomposed by
P-C reductive elimination below room temperature,
and this reactivity appears to be general for such
complexes.3g,6 However, Pd complexes 9 and 11 are
thermally stable, and 9 showed no traces of decomposi-
tion on heating at 60 °C for 3 days or heating to 100 °C
for 30 min. The chelate may prevent reductive elimina-
tion by restricting approach of the P and C atoms, or
ring strain in the putative product might make P-C
bond formation thermodynamically unfavorable.
Pd complexes 9 (as a pentane hemisolvate) and 11
were further characterized by X-ray crystallography (see
Figures 1 and 2 for ORTEP diagrams and Table 3 and
the Supporting Information for details of data collection
and refinement). As observed in analogous Pt com-
plexes, the phosphido P atoms are pyramidal (sum of
angles 319.6 and 324.6°, respectively).3
spectroscopic data agree well with those for the analo-
gous dppe complexes [M(dppe)(Me)(PMes2H)]+ (M ) Pd
(3), Pt (4)).7
As previously reported for 3 and 4, thermolysis of 1
and 2 (Scheme 1) produced the cyclometalated com-
plexes [M(dppen)(CH2C6H2Me2P(Mes)(H))][OTf] (M )
1
Pd (5), Pt (6)) as white solids (Table 1).7 In the H{31P}
NMR spectra (CD2Cl2) of 5 and 6 the cyclometalated
CH2 protons appear as AB patterns at δ 3.68-3.57 (2J HH
) 15 Hz) and 3.98-3.56 (2J HH ) 18 Hz), respectively.
In the 13C{1H} NMR spectra (CD2Cl2) of 5 and 6 the
M-CH2 groups gave rise to doublets at δ 40.8 (2J PC
)
84 Hz) and 34.8 (2J PC ) 78 Hz), respectively. This is
consistent with the observations for the dppe complexes
[M(dppe)(CH2C6H2Me2P(Mes)(H))][OTf] (M ) Pd (7), Pt
(8)).7
Deprotonation of 5-8 with LiN(SiMe3)2, NaN(SiMe3)2,
or other bases gave the neutral phosphido compounds
M(diphos)(CH2C6H2Me2P(Mes)) (diphos ) dppen, M )
Pd (9), M ) Pt (10); diphos ) dppe, M ) Pd (11), M )
Pt (12)) (Scheme 1). Since these neutral complexes
tended to cocrystallize with LiOTf or NaOTf, we pre-
The structures of 9‚0.5C5H12 and 11, which are very
similar, may be compared to that of the previously
(7) Zhuravel, M. A.; Grewal, N. S.; Glueck, D. S.; Lam, K.-C.;
Rheingold, A. L. Organometallics 2000, 19, 2882-2890.

3210 Organometallics, Vol. 21, No. 15, 2002
Zhuravel et al.
Ta ble 3. Cr ysta llogr a p h ic Da ta for
P d (d p p en )(CH2C6H2Me2P (Mes))‚0.5C5H12
(9‚0.5C5H12) a n d P d (d p p e)(CH2C6H2Me2P (Mes)) (11)
9‚0.5C5H12
11
formula
fw
space group
a, Å
b, Å
c, Å
C
46.5H49P3Pd
C44H45P3Pd
773.11
P1h
807.17
P21/n
9.4352(17)
23.389(4)
18.249(3)
90
90.213(4)
90
9.6982(7)
11.7577(8)
16.9489(12)
79.3180(10)
80.2990(10)
88.0510(10)
1872.0(2)
2
R, deg
â, deg
γ, deg
V, Å3
4027.2(12)
4
Z
D(calcd), g/cm3
µ(Mo KR), mm-1
temp, K
diffractometer
radiation
R(F), %a
Rw(F2), %a
1.331
0.611
223(2)
Siemens P4 CCD
MoKR (0.710 73 Å)
4.02
1.372
0.654
221(2)
Siemens P4 CCD
MoKR (0.710 73 Å)
3.83
9.87
13.49
F igu r e 1. ORTEP diagram of Pd(dppen)(CH2C6H2Me2P-
(Mes))‚0.5C5H12 (9‚0.5C5H12) with thermal ellipsoids at 30%
probability. Hydrogen atoms and the disordered solvent
molecule are not shown.
Quantity minimized ) Rw(F2) ) ∑[w(Fo2 - Fc2)2]/∑[(wFo2)2]1/2
;
a
R ) ∑∆/∑(Fo), ∆ ) |(Fo - Fc)|, w ) 1/[σ2(Fo2) + (aP)2 + bP], P )
2
[2Fc + Max(Fo,0)]/3.
Ta ble 4. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for th e Cyclom eta la ted Com p lexes
[P d (d p p e)(CH2C6H2Me2P (Mes)(H))][OTf]‚0.5C7H8
(7‚0.5C7H8),a P d (d p p e)(CH2C6H2Me2P (Mes)) (11),
a n d P d (d p p en )(CH2C6H2Me2P (Mes))‚0.5C5H12
(9‚0.5C5H12
7‚0.5C7H8
)
11
9‚0.5C5H12
Bond Lengths
Pd-C(35)
Pd-P(1)
2.137(13)
2.415(3)
2.381(3)
2.380(3)
1.909(11)
1.904(10)
2.080(3)
2.3266(8)
2.3143(8)
2.3270(8)
1.816(4)
1.844(3)
2.091(4)
2.3104(11)
2.3025(12)
2.3292(12)
1.837(4)
Pd-P(2)
Pd-P(3)
P(3)-C(27)
P(3)-C(36)
1.855(4)
Bond Angles
C(35)-Pd-P(1)
C(35)-Pd-P(2)
P(2)-Pd-P(1)
C(35)-Pd-P(3)
P(2)-Pd-P(3)
P(1)-Pd-P(3)
Pd-P(3)-C(27)
Pd-P(3)-C(36)
C(27)-P(3)-C(36)
174.1(3)
90.0(3)
84.54(9)
82.7(3)
172.72(9)
102.74(10)
104.7(4)
121.1(3)
110.7(5)
173.71(10)
90.60(9)
85.93(3)
175.00(13)
92.51(12)
85.44(4)
83.49(12)
170.19(4)
99.24(4)
102.35(13)
112.30(14)
104.92(18)
83.34(9)
164.03(3)
101.34(3)
102.44(10)
114.51(10)
107.60(14)
F igu r e 2. ORTEP diagram of Pd(dppe)(CH2C6H2Me2P-
(Mes)) (11) with thermal ellipsoids at 30% probability.
Hydrogen atoms are not shown.
a
Zhuravel, M. A.; Grewal, N. S.; Glueck, D. S.; Lam, K.-C.;
reported [Pd(dppe)(CH2C6H2Me2P(Mes)(H))][OTf] (7‚
0.5C7H8);7 for selected bond lengths and angles, see
Table 4. Interestingly, all three Pd-P bonds, as well as
the Pd-C bond, are shorter in neutral 9 and 11 than in
the related cationic precursor 7. In contrast, conversion
of trans,mer-[IrCl2(PH3)(PMe2Ph)3]+ to neutral trans,-
mer-[IrCl2(PH2)(PMe2Ph)3] led to an increase in the
Ir-P(phosphido) bond length.8 Perhaps the structural
changes in the Pd complexes may be ascribed to reduced
steric hindrance at the crowded P atom upon deproto-
nation.
Rheingold, A. L. Organometallics 2000, 19, 2882-2890.
two more are observed for the m-Mes protons. At high
temperature, these signals coalesce separately to give
an averaged spectrum with equivalent ortho and meta
groups. The rotational barriers thus measured range
from 14.4 to 15.4 kcal/mol, with good agreement be-
tween the results obtained from coalescence of the two
groups of signals.9
Similar coalescence behavior was observed for the
o-Me and m-Mes resonances in the variable-tempera-
1
ture H{31P} NMR spectra of neutral phosphido com-
Va r ia ble-Tem p er a tu r e NMR Beh a vior . The ob-
servation of five separate signals due to methyl groups
plexes 9-12 (Table 6). Moreover, the signals due to the
diastereotopic CH2 protons also show dynamic behavior.
In the low-temperature limit, AB patterns were ob-
served, while at high temperature these protons are
equivalent, yielding singlet signals. Measurement of the
coalescence temperatures for the three separate groups
1
in the H NMR spectrum of 8 (CD2Cl2, 21 °C) prompted
a variable-temperature study of rotation about the
P-C(Mes) bond in cations 5-8 (Table 5). In the low-
temperature limit, when rotation is slow on the NMR
time scale, the o-Me protons give rise to two resonances;
(8) Deeming, A. J .; Doherty, S.; Marshall, J . E.; Powell, J . L.; Senior,
A. M. J . Chem. Soc., Dalton Trans. 1993, 1093-1100.
(9) Friebolin, H. In Basic One- and Two-Dimensional NMR Spec-
troscopy, 2nd ed.; VCH: New York, 1993; pp 287-314.

Palladium(II) Terminal Phosphido Complexes
Organometallics, Vol. 21, No. 15, 2002 3211
Ta ble 5. Va r ia ble-Tem p er a tu r e 1H{31P } NMR Da ta
for Ca tion ic Com p lexes of Cyclom eta la ted
Dim esitylp h osp h in ea
Ch a r t 1
q
complex
(M(diphos))
∆ν
Tc
∆Gc
resonance
δ (ppm)
(Hz) (K) (kcal/mol)
5 (Pd(dppen))
6 Pt(dppen))
7 Pd(dppe))
8 (Pt(dppe))
Me
Ar
Me
Ar
Me
Ar
Me
Ar
2.12, 1.68 217 319
6.81, 6.48 162 314
2.11, 1.71 203 319
6.78, 6.45 162 319
14.8
14.8
14.9
15.0
14.5
14.4
15.4
15.4
1.95, 1.86
6.72, 6.62
1.99, 1.87
6.71, 6.60
48 294
53 294
57 314
58 314
[P(R)(R′)] (diphos ) diphosphine, X ) alkyl (A), C(O)-
C3F7 (B); Chart 1), such barriers range from 11 to 16
kcal/mol, similar in magnitude to the barriers described
above for 9-12.3c,d
a
Legend and conditions: anion BF4; solvent CD2Cl2 for 7, CDCl3
for 5, 6, and 8; chemical shifts and ∆ν values from slow-exchange
spectra at -40 °C for 5, -20 °C for 6, 0 °C for 7, and 21 °C for 8;
estimated errors are different for each resonance, “typical” errors
are 5 Hz in ∆ν, 10 °C in Tc, and 0.5 kcal/mol in ∆Gc
q
.
The M-CH2 protons in phosphido complexes 9-12
1
Ta ble 6. Va r ia ble-Tem p er a tu r e 1H{31P } NMR Da ta
for Ter m in a l P h osp h id o Com p lexes Der ived fr om
Cyclom eta la ted Dim esitylp h osp h in ea
were intended to serve as H NMR spectroscopic probes
of phosphorus inversion. As for the diastereotopic CF2
fluorines in B, the diastereotopic protons in a CH2 group
are expected to have different chemical shifts if inver-
sion is slow on the NMR time scale, while rapid
phosphorus inversion via a planar transition state
makes them equivalent. As foreseen, the 1H NMR
signals due to the CH2 groups are singlets in the high-
temperature limit, consistent with rapid P inversion.
In the low-temperature spectra, AB patterns are ob-
served, consistent with slow inversion on the NMR time
scale. Since rotation about the M-P bond is prevented
by the chelate, the measured barriers are those for a
pure inversion process.
This analysis assumes that both chelate rings can
access a conformation in which the square plane of the
molecule is a plane of symmetry. Further, the P-Mes
group must be able to occupy the square plane or be
perpendicular to it. The latter conformation, with a
pyramidal P, is similar to that observed in the solid-
state structure of 9. If this conformation is maintained
in solution, then the o-Me and m-H positions of the
P-Mes group could be made equivalent at high tem-
perature either by rotation about the P-C(Mes) bond
or by P inversion via a planar transition state. The low-
temperature NMR observations of these inequivalent
Mes signals then require both these processes to be slow
on the NMR time scale.11
Since the coalescence behavior of the CH2 proton
signals and those from the P-Mes group leads to the
same barriers, this analysis suggests that the barrier
to P-C(Mes) rotation is greater than or equal to the
inversion barrier. This is consistent with the measured
rotation barriers in cations 5-8, which should be a good
model for those in neutral complexes 9-12; barriers to
rotation and inversion are probably similar in magni-
tude.
The variable-temperature NMR behavior of samples
of 9-12 which contained LiOTf was identical with that
of salt-free material, which suggests that inversion does
not occur via heterolytic cleavage of the M-P bonds to
give an ionic intermediate. Instead, as commonly as-
q
complex
∆ν
Tc
∆Gc
(M(diphos))
resonance
δ (ppm)
(Hz) (K) (kcal/mol)
9 (Pd(dppen))
10 (Pt(dppen))
11 (Pd(dppe))
12 (Pt(dppe))
CH2
Me
Ar
CH2
Me
Ar
CH2
Me
Ar
CH2
Me
Ar
4.30, 3.63b 332 321
14.6
14.6
14.4
13.3
f
13.3
14.5
14.4
14.2
13.0
13.6
13.2
2.76, 2.00
6.62, 6.34
4.39, 4.34c
380 323
140 306
21 270
6.55, 6.18
183 286
3.91, 3.58d 163 309
2.46, 2.31
6.62, 6.49
164 297
61 292
4.17, 3.73e 217 281
2.46, 2.41
6.50, 6.31
27 271
97 276
a
Legend and conditions: solvent toluene-d8; chemical shifts,
∆ν values, and coupling constants from slow-exchange spectra at
-40 °C (9), -75 °C (10), -20 °C (11), and -60 °C (12); estimated
errors are different for each resonance, “typical” errors are 5 Hz
q
b
c
in ∆ν, 10 °C in Tc, and 0.5 kcal/mol in ∆Gc
.
J HH ) 14 Hz. J HH
d
) 18 Hz; J PtH ) 83 Hz (δ 4.39), 55 Hz (δ 4.34). J HH ) 14 Hz.
e J HH ) 17.5 Hz, J PtH ) 85 Hz (δ 4.17), 50 Hz (δ 3.73). f Not
observed.
of signals in these spectra provides approximate free
energies of activation for the dynamic processes (Table
6).9 The good agreement between the data obtained for
the three different groups suggests that the same
process(es) are responsible in each case. The similarity
of the barriers for the dppe and dppen complexes
indicates that conformational changes in the dppe ring
are not involved. The observed barriers are similar for
Pd and Pt complexes.
Dyn a m ic P r ocesses. Pyramidal inversion at phos-
phorus in metal phosphido complexes is rapid on the
NMR time scale.10 Variable-temperature NMR observa-
tions provide barriers to a composite process, which
includes both P inversion and rotation about the M-P
bond. For the Pt phosphido complexes Pt(diphos)(X)-
(10) (a) Rogers, J . R.; Wagner, T. P. S.; Marynick, D. S. Inorg. Chem.
1994, 33, 3104-3110. (b) Buhro, W. E.; Gladysz, J . A. Inorg. Chem.
1985, 24, 3505-3507. (c) Simpson, R. D.; Bergman, R. G. Organome-
tallics 1992, 11, 3980-3993. (d) Crisp, G. T.; Salem, G.; Wild, S. B.;
Stephan, F. S. Organometallics 1989, 8, 2360-2367. (e) Malisch, W.;
Maisch, R.; Meyer, A.; Greissinger, D.; Gross, E.; Colquhoun, E. J .;
McFarlane, W. Phosphorus Sulfur Relat. Elem. 1983, 18, 299-302. (f)
Baker, R. T.; Whitney, J . G.; Wreford, S. S. Organometallics 1983, 2,
1049-1051. (g) Bonnet, G.; Kubicki, M. M.; Moise, C.; Lazzaroni, R.;
Salvadori, P.; Vitulli, G. Organometallics 1992, 11, 964-967. (h)
Fryzuk, M. D.; J oshi, K.; Chadha, R. K.; Rettig, S. J . J . Am. Chem.
Soc. 1991, 113, 8724-8736. (i) References 3a-d.
(11) If the P(Mes) group adopts a low-temperature conformation
which is unsymmetrical with respect to the square plane (i.e., neither
parallel nor perpendicular to it), then the CH2 protons as well as the
o-Me groups and m-H protons would be inequivalent. In this case, the
measured barriers would reflect only P-C(Mes) rotation. We favor the
simpler explanation in the text, however.

3212 Organometallics, Vol. 21, No. 15, 2002
Zhuravel et al.
1H NMR (CD2Cl2): δ 7.85-7.71 (m, 4H, Ph), 7.67-7.59 (m,
4H, Ph), 7.56-7.41 (m, 12H, Ph), 7.36-7.06 (m, 2H, CH), 0.64
(dd, 3H, J ) 4, 6, J PtH ) 56). 31P{1H} NMR (CD2Cl2): δ 55.9
(d, J ) 11, J PtP ) 1745), 46.7 (d, J ) 11, J PtP ) 4221). 13C{1H}
NMR (CD2Cl2): δ 147.4 (dd, J ) 34, 55, CH), 146.0 (dd, J )
19, 43, CH), 133.5-133.2 (m), 131.9 (d, J ) 3), 131.4, 131.2
(d, J ) 3), 129.3-129.1 (m), 128.7, 6.1 (dd, J ) 98, 6, Me, Pt
satellites not observed). IR: 3050, 2989, 2932, 2876, 2793,
1586, 1482, 1435, 1307, 1184, 1159, 1103, 1069, 1026, 998, 848,
sumed, we believe that inversion proceeds via a pla-
nar-P transition state.
Con clu sion
Deprotonation of cationic Pd(II) and Pt(II) complexes
derived from cyclometalated dimesitylphosphine gave
neutral terminal phosphido compounds, including un-
usual stable Pd phosphido alkyls. As in closely related
complexes, the variable-temperature NMR behavior is
consistent with low barriers (13-15 kcal/mol) to phos-
phorus inversion, which are similar for Pd and Pt
compounds. In contrast to previous work, incorporating
the phosphido group in a chelate ring enabled measure-
ment of pure inversion barriers by stopping rotation
about the M-P bond.
739, 720, 699 cm-1
.
[P d (d p p en )(Me)(P Mes2H)][OTf] (1). To a slurry of Pd-
(dppen)(Me)(Cl) (213 mg, 0.39 mmol) in 3 mL of a THF/MeCN
mixture (10:1) was added AgOTf (99 mg, 0.39 mmol) and
PMes2H (104 mg, 0.39 mmol). Grey precipitate formed in-
stantly, and the reaction mixture was allowed to stand for 15
min. The solution was filtered, and the solvent was removed
under vacuum. The resulting crude product was washed with
3 × 10 mL of petroleum ether and dried in vacuo to give the
final product as 336 mg (93% yield) of white solid. Anal. Calcd
for C46H48P3SO3F3Pd: C, 58.95; H, 5.16. Found: C, 58.59; H,
5.25.
Exp er im en ta l Section
Gen er a l Deta ils. Unless otherwise noted, all reactions and
manipulations were performed in dry glassware under a
nitrogen atmosphere at 20 °C in a drybox or using standard
Schlenk techniques. Petroleum ether (bp 38-53 °C), ether,
THF, and toluene were dried and distilled before use by
employing Na/benzophenone. CH2Cl2 was distilled from CaH2.
Acetone and acetonitrile were degassed by purging with N2
and stored over molecular sieves.
1H NMR (CD2Cl2): δ 7.68-7.16 (m, 22H), 6.79 (d, J ) 3,
4H, Mes), 6.61 (dd, J ) 360, 12, 1H, P-H), 2.25 (6H, Me), 2.09
(12H, Me), 0.52-0.45 (m, 3H, Me). 31P{1H} NMR (CD2Cl2): δ
64.6 (dd, J ) 12, 373), 54.4 (dd, J ) 12, 33), -47.6 (dd, J )
373, 33). 13C{1H} NMR (CD2Cl2): δ 147.0-145.8 (m), 142.2 (d,
J ) 8), 141.8, 133.2 (d, J ) 11), 132.6 (d, J ) 4), 132.4 (d, J )
12), 132.1 (d, J ) 2), 130.7 (d, J ) 7), 130.0 (d, J ) 11), 129.7
(d, J ) 9), 128.7 (d, J ) 40), 128.2 (d, J ) 51), 120.7-120.0
(m), 23.3 (d, J ) 10, Me), 21.0 (d, J ) 1, Me), 5.2 (d, J ) 81,
Me). IR: 3054, 2967, 2919, 2389, 1603, 1557, 1437, 1379, 1268,
NMR spectra were recorded with Varian 300 and 500 MHz
1
spectrometers. H and 13C NMR chemical shifts are reported
vs Me4Si and were determined by reference to the residual 1H
or 13C solvent peaks. 31P NMR chemical shifts are reported vs
H3PO4 (85%) used as an external reference. Coupling constants
are reported in Hz. Unless otherwise noted, peaks in NMR
spectra are singlets. Infrared spectra were recorded on a
Perkin-Elmer 1600 series FTIR machine and are reported in
cm-1. Elemental analyses were provided by Schwarzkopf
Microanalytical Laboratory.
1223, 1150, 1101, 1030, 853, 749, 697 cm-1
.
[P t(d p p en )(Me)(P Mes2H)][OTf] (2). To a slurry of Pt-
(dppen)(Me)(Cl) (82 mg, 0.13 mmol) in 2 mL of THF was added
0.1 mL of MeCN, AgOTf (33 mg, 0.13 mmol), and PMes2H (35
mg, 0.13 mmol), and the resulting gray slurry was stirred for
5 min. The solution was filtered, petroleum ether was added,
and cooling to -25 °C gave the product as 115 mg (88% yield)
of white solid. Anal. Calcd for C46H48P3SO3F3Pt: C, 53.85; H,
4.72. Found: C, 54.07; H, 4.95.
Unless otherwise noted, reagents were from commercial
suppliers. The following compounds were made by the litera-
ture procedures: Pd(cod)(Me)(Cl),12 Pt(cod)(Me)(Cl),13 PMes2H,14
and cyclometalated cations 7 and 8.7
P d (d p p en )(Me)(Cl). To a slurry of Pd(cod)(Me)(Cl) (376
mg, 1.42 mmol) in 10 mL of toluene was added dppen (565
mg, 1.42 mmol), and the mixture was stirred for 2 days. The
solution was decanted, and the solid residue was washed with
3 × 10 mL of ether and dried in vacuo to give the product as
735 mg (94% yield) of off-white solid. Anal. Calcd for C27H25P2-
ClPd: C, 58.61; H, 4.55. Found: C, 58.23; H, 4.65.
1H NMR (CD2Cl2): δ 7.70-7.42 (m, 13H), 7.38-7.26 (m, 9H),
1
6.79 (d, J ) 3, 4H, Mes), 6.95 (dm, J PH ) 366, 1H, PH), 2.26
2
(6H, Me), 2.13 (12H, Me), 0.64-0.37 (m, J PtH ) 60, 3H).
31P{1H} NMR (CD2Cl2): δ 59.1 (dd, J ) 8, 387, J PtP ) 2852),
55.9 (dd, J ) 8, 16, J PtP ) 1711), -50.0 (dd, J ) 16, 387, J PtP
) 3377). 13C{1H} NMR (CD2Cl2): δ 148.3-145.5 (m), 142.5-
142.1 (m), 133.4-133.1 (m), 132.7-132.2 (m), 130.7 (d, J )
9), 129.9 (d, J ) 11), 129.5 (d, J ) 10), 128.4, 128.0, 127.6,
127.1, 119 (m), 23.3 (m), 21.0, -2.5 (dm, J ) 74, J PtC ) 529,
Me). IR: 3054, 2967, 2920, 2372, 1603, 1557, 1437, 1272, 1223,
1H NMR (CD2Cl2): δ 7.77-7.71 (m, 4H, Ph), 7.65-7.57 (m,
4H, Ph), 7.56-7.40 (m, 13H), 7.25 (ddd, 1H, J ) 9, 11, 55, CH),
0.76 (dd, 3H, J ) 8, 3, Me). 31P{1H} NMR (CD2Cl2): δ 66.6 (d,
J ) 14), 50.2 (d, J ) 14). 13C{1H} NMR (CD2Cl2): δ 147.7 (dd,
J ) 44, 43, CH), 144.9 (dd, J ) 34, 25, CH), 133.5-133.2 (m),
132.1, 131.8 (d, J ) 3), 131.1 (d, J ) 2), 130.3-129.9 (m),
129.5-129.2 (m), 128.6, 9.4 (d, J ) 106, Me). IR: 3048, 2977,
2884, 1584, 1571, 1481, 1434, 1307, 1184, 1135, 1101, 1069,
1151, 1101, 1030, 852, 749, 697 cm-1
.
[P d (d p p en )(CH2C6H2Me2P (Mes)(H))][OTf] (5). A solu-
tion of 1 (72 mg, 0.08 mmol) in 1 mL of THF was placed in an
NMR tube and heated at 60-65 °C for 3 days. The resulting
orange solution was filtered, petroleum ether was added, and
cooling to -30 °C gave the product as 45 mg (63% yield) of
orange solid. Anal. Calcd for C45H44P3SO3F3Pd: C, 58.67; H,
4.81. Found: C, 58.48; H, 4.81.
1026, 998, 848, 741, 695 cm-1
.
P t(d p p en )(Me)(Cl). To a slurry of Pt(cod)(Me)(Cl) (99 mg,
0.28 mmol) in 4 mL of toluene was added dppen (120 mg, 0.31
mmol). After 2 h of stirring the solution was decanted, and
the solid residue was washed with 3 × 10 mL of ether and
dried in vacuo to give the product as 155 mg (86% yield) of
white solid. Anal. Calcd for C27H25P2ClPt: C, 50.51; H, 3.93.
Found: C, 50.37; H, 3.79.
1H NMR (CD2Cl2): δ 7.70-7.26 (m, 18H), 7.06-6.98 (m,
3H), 6.83-6.65 (m, 5H), 3.63 (br, 2H, Pd-CH2), 2.27 (6H), 2.10
(br, 3H), 1.91 (3H), 1.78 (br, 3H). 31P{1H} NMR (CD2Cl2): δ
56.9 (dd, J ) 344, 16), 50.7 (dd, J ) 29, 16), -19.7 (dd, J )
344, 29). 13C{1H} NMR (CD2Cl2): δ 157.2-156.9 (m), 147.6-
147.0 (m), 145.4-144.8 (m), 143.9 (m), 142.7, 142.3 (m),
134.0 (d, J ) 14), 133.2-133.1 (m), 132.7 (d, J ) 3), 132.6 (d,
J ) 2), 131.1, 131.0 (m), 130.3-130.0 (m), 129.8, 129.7, 129.4
(d, J ) 10), 129.2, 128.9, 128.8-128.6 (m), 128.5, 128.2, 128.1,
127.7, 125.2-124.8 (m), 122.6, 122.1, 121.7, 120.1, 117.5, 40.8
(d, J ) 84), 23.0-22.2 (br m), 21.2-21.1 (m), 20.1-20.0 (m).
IR: 2918, 2384 (PH), 1601, 1563, 1436, 1070, 893, 852, 745,
696.
(12) Dekker, G. P. C. M.; Buijs, A.; Elsevier, C. J .; Vrieze, K.; van
Leeuwen, P. W. N. M.; Smeets, W. J . J .; Spek, A. L.; Wang, Y. F.; Stam,
C. H. Organometallics 1992, 11, 1937-1948.
(13) Clark, H. C.; Manzer, L. E. Inorg. Chem. 1974, 13, 1291-1297.
(14) Bartlett, R. A.; Olmstead, M. M.; Power, P. P.; Sigel, G. A. Inorg.
Chem. 1987, 26, 1941-1946.

Palladium(II) Terminal Phosphido Complexes
Organometallics, Vol. 21, No. 15, 2002 3213
[P t(d p p en )(CH2C6H2Me2P (Mes)(H))][OTf] (6). In air, a
25 mL ampule was charged with a solution of [Pt(dppen)(Me)-
(PHMes2)][OTf] (2; 480 mg, 0.47 mmol) in Cl2HCCHCl2 (6 mL).
The ampule was evacuated, and the solution was heated at
95-100 °C for 3 days. The solvent was then removed under
reduced pressure to give the crude product as a yellow oil,
which was washed with 5 × 20 mL of petroleum ether and
dried in vacuo to give the final product as 412 mg (87% yield)
of white solid. Anal. Calcd for C45H44SO3F3P3Pt: C, 53.52; H,
4.39. Found: C, 53.82; H, 4.65.
light orange chunks. Anal. Calcd for C44H43P3Pt: C, 61.46; H,
5.04. Found: C, 61.45; H, 5.13.
1H{31P} NMR (toluene-d8, 55 °C): δ 7.58 (m, 5H), 7.08-6.92
(m, 15H, obscured by toluene-d8), 6.87-6.75 (m, 3H), 6.56 (1H),
6.42 (2H), 4.11 (J PtH ) 71, 2H), 2.37 (very br, 3H), 2.22 (3H),
2.11-2.08 (br, 6H, obscured by toluene-d8), 2.03 (3H). 1H{31P}
NMR (toluene-d8, 21 °C): δ 7.58 (br, 5H), 7.14-6.98 (m, 15H,
obscured by toluene-d8), 6.82-6.69 (m, 3H), 6.61 (1H), 6.44
(very br, 2H), 4.16 (br, J PtH ) 70, 2H), 2.60 (very br, 3H), 2.25
(3H), 2.13-2.12 (br, 6H), 2.10 (3H, obscured by toluene-d8).
1H{31P} NMR (toluene-d8, -75 °C): δ 8.11 (d, J ) 7, 2H), 7.64
(d, J ) 7, 2H), 7.34 (d, J ) 8, 2H), 7.29 (2H), 7.20-6.78 (m,
12H, obscured by toluene-d8), 6.70-6.63 (m, 3H), 6.55 (1H),
6.49 (m, 1H), 6.18 (1H), 4.39 (br, AB, J ) 18, J PtH ) 83, 1H),
4.34 (br, AB, J ) 18, J PtH ) 55, 1H), 2.87 (3H), 2.35 (3H), 2.22
(6H), 2.15 (3H). 31P{1H} NMR (toluene-d8, 21 °C): δ 58.0 (d, J
) 13, J PtP ) 1935), 56.9 (dd, J ) 140, 13, J PtP ) 1895), 10.6 (d,
J ) 140, J PtP ) 1102). IR: 3053, 2916, 1599, 1553, 1436, 1260,
1H NMR (CD2Cl2): δ 7.80-7.12 (m, 19H), 7.08-6.98 (m, 3H),
2
6.80-6.69 (m, 4H), 6.51 (br, 1H), 3.98-3.56 (m, 2H, J HH
)
17.5, CH2), 2.27 (6H, Me), 2.14 (br, 3H, Me), 1.92 (br, 3H, Me),
1.76 (br, 3H, Me). 31P{1H} NMR (CD2Cl2): δ 61.5 (dd, J ) 358,
8, J PtP ) 2757), 59.3 (dd, J ) 13, 8, J PtP ) 1786), -16.7 (dd, J
) 358, 13, J PtP ) 2681). 13C{1H} NMR (CD2Cl2): δ 157.7-157.3
(m), 149.0-148.4 (m), 147.1 (m), 145.1-144.2 (m), 143.0-142.3
(m), 140.0 (br), 134.4-134.1 (m), 133.5-133.0 (m), 133.0-132.7
(m), 131.1-130.9 (m), 130.2-129.9 (m), 129.7-129.5 (m), 129.2
(d, J ) 11), 128.7, 128.3, 128.0, 127.8, 127.6, 127.4, 125.3-
124.7 (m), 122.6, 121.5, 121.1, 120.1, 34.8 (dm, J ) 78), 22.9-
22.6 (m), 22.2-21.9 (m), 21.1 (m), 20.2 (m). IR: 3054, 3006,
2920, 2391, 1603, 1564, 1483, 1437, 1379, 1278, 1223, 1148,
1169, 1102, 1032, 849 cm-1
.
P d (d p p e)(CH2C6H2Me2P (Mes)) (11). 11 was obtained in
55% yield; recrystallization from toluene/petroleum ether gave
orange blocks suitable for X-ray crystallography. Anal. Calcd
for C44H45P3Pd: C, 68.35; H, 5.87. Found: C, 68.36; H, 5.76.
1H{31P} NMR (toluene-d8, -20 °C): δ 7.89 (m, 2H), 7.54 (m,
2H), 7.45 (m, 2H), 7.13-6.81 (m, 15H), 6.69 (1H), 6.62 (1H),
6.49 (1H), 3.91 (AB, J ) 14, 1H), 3.58 (AB, J ) 14, 1H), 2.46
(3H), 2.31 (3H), 2.27 (3H), 2.16 (3H), 2.13 (3H), 1.88-1.81 (br,
1103, 1071, 1031, 895, 853, 819, 743, 722 cm-1
.
M(d ip h os)(CH2C6H2Me2P (Mes)) (9-12: M ) P d , P t;
d ip h os ) d p p en , d p p e). Treatment of cations 5-8 with LiN-
(SiMe3)2, NaN(SiMe3)2, or other bases gave neutral complexes
9-12 in quantitative yields, according to 31P NMR. However,
we could not separate LiOTf from the metal complexes, and
NaOTf could be removed only after repeated recrystallizations.
Therefore, BF4 salts of cations 5-8 were prepared using AgBF4
instead of AgOTf; their NMR spectra were identical with those
of the triflate salts. Deprotonation of 5(BF 4)-8(BF 4) with
NaN(SiMe3)2 enabled separation of the less soluble NaBF4 to
give pure 9-12 after recrystallization. These complexes are
yellow or orange solids which are sparingly soluble in toluene,
once pure. Details of the synthesis of 10 are provided below;
preparations of the other complexes were very similar.
P d (d p p en )(CH2C6H2Me2P (Mes)) (9). 9 was obtained in
82% yield; several recrystallizations from toluene/petroleum
ether gave orange-yellow crystals suitable for X-ray crystal-
lography and for elemental analysis. Both techniques showed
the presence of 0.5 equiv of cocrystallized pentane. Anal. Calcd
for C44H43P3Pd‚0.5C5H12: C, 69.19; H, 6.12. Found: C, 68.94;
H, 5.81.
1
3H), 1.72-1.66 (br, 1H). H{31P} NMR (toluene-d8, 21 °C): δ
7.91 (br, 2H), 7.55 (br, 4H), 7.19-6.78 (br m, 15H), 6.68 (1H),
6.64-6.46 (m, 2H), 3.88 (br, 1H), 3.57 (br, 1H), 2.48-2.25 (very
br, 6H), 2.25 (3H), 2.12 (3H), 2.10 (3H), 1.94-1.80 (very br,
4H). 1H{31P} NMR (toluene-d8, 60 °C): δ 7.58 (m, 4H),
7.10-6.92 (m, 17H), 6.65 (1H), 6.53 (2H), 3.69 (br, 2H), 2.34
(br, 6H), 2.23 (3H), 2.10 (3H), 2.06 (3H), 1.97-1.94 (m, 2H),
1.92-1.89 (m, 2H). 31P{1H} NMR (toluene-d8, 21 °C): δ 36.4
(dd, J ) 124, 21), 34.4 (dd, J ) 21, 8), 24.7 (dd, J ) 124, 8).
13C{1H} NMR (toluene-d8, 21 °C): δ 153.9-153.6 (m), 144.8-
144.6 (m), 141.7 (m), 141.4 (m), 140.0-139.9 (m), 137.8,
135.5, 134.5, 134.8-131.8 (very br m), 130.3 (br), 129.1-128.2
(m), 127.2, 125.4, 36.8 (dm, J ) 85, Pd-CH2), 30.0-29.7 (m,
PCH2), 27.9-27.6 (m, PCH2), 24.8 (br, Me), 21.2 (Me), 21.1
(Me), 21.0 (Me).
P t(d p p e)(CH2C6H2Me2P (Mes)) (12). 12 was obtained in
37% yield; repeated recrystallization from toluene/petroleum
ether gave orange chunks. Anal. Calcd for C44H45P3Pt: C,
61.32; H, 5.26. Found: C, 61.34; H, 5.28.
1H{31P} NMR (toluene-d8, 70 °C): δ 7.67-7.65 (m, 5H),
7.15-7.02 (m, 18H, obscured by toluene-d8), 6.74 (1 H), 6.60
(2H), 3.85 (br, 2H), 2.42 (very br, 3H, Me), 2.33 (3H, Me), 2.21
(6H, obscured by toluene-d8, Me), 2.13 (3H, Me). 1H{31P} NMR
(toluene-d8, 21 °C): δ 7.97 (br, 2H), 7.55 (br, 4H), 7.12-6.66
(m, 18H, obscured by toluene-d8), 6.61 (br, 1H), 6.41 (br, 1H),
4.11 (br, 1H, CH2), 3.50 (br, 1H, CH2), 2.68 (br, 3H, Me), 2.28
(3H, Me), 2.13 (6H, Me), 2.00 (br, 3H, Me). 1H{31P} NMR
(toluene-d8, -40 °C): δ 7.97 (m, 2H), 7.54 (d, J ) 7, 2H), 7.47
(m, 2H), 7.18-6.66 (m, 18H, obscured by toluene-d8), 6.62 (1H),
6.34 (1H), 4.30 (AB pattern, J ) 14, 1H), 3.63 (AB, J ) 14,
1H), 2.76 (3H, Me), 2.33 (3H, Me), 2.18 (3H, Me), 2.13 (3H,
Me), 2.00 (3H, Me). 31P{1H} NMR (toluene-d8): δ 51.0 (dd, J
) 124, 3), 50.7 (dd, J ) 7, 3), 34.1 (dd, J ) 124, 7). IR: 3051,
1H{31P} NMR (toluene-d8, 40 °C): δ 7.58 (5H), 7.09-6.95
(m, 16H, obscured by toluene-d8), 6.57 (1H), 6.44 (2H), 3.94
(J PtH ) 70, 2H), 2.37 (6H), 2.20 (3H), 2.11 (3H), 2.05 (3H),
1.89-1.78 (br m, 4H). 1H{31P} NMR (toluene-d8, 21 °C): δ
7.68 (5H), 7.19-7.06 (m, 16H, obscured by toluene-d8), 6.70
(1H), 6.56 (2H), 4.07 (br, 2H), 2.50 (br, 6H), 2.32 (3H), 2.22
(3H), 2.21 (3H), 2.04-1.84 (br, 4H). 1H{31P} NMR (toluene-
d8, -60 °C): δ 8.08 (m, 2H), 7.54 (m, 2H), 7.21 (m, 2H), 7.08-
6.74 (m, 13H, obscured by toluene-d8), 6.65-6.62 (m, 2H), 6.54
(1H), 6.50 (1H), 6.31 (1H), 4.17 (br, AB, J ) 17.5, J PtH ) 85,
1H), 3.73 (br, AB, J ) 17.5, J PtH ) 50, 1H), 2.46 (3H), 2.41
(3H), 2.18 (3H), 2.12 (3H), 2.09 (3H), 1.84-1.82 (br, 2H), 1.55-
1.35 (br, 2H). 31P{1H} NMR (toluene-d8, 21 °C): δ 47.9 (d, J )
2914, 1599, 1435, 1262, 1159, 1100, 1031, 848, 736 cm-1
.
143, J PtP ) 1922), 45.9 (J PtP ) 1933), 8.8 (d, J ) 143, J PtP )
1112).
P t(d p p en )(CH2C6H2Me2P (Mes)) (10). A solution of 6(BF 4)
(150 mg, 0.165 mmol) in 3 mL of THF was treated with NaN-
(SiMe3)2 (30 mg, 0.17 mmol) to give a deep red solution, which
was filtered through Celite. Adding petroleum ether gave a
cloudy orange solution, which was cooled to -25 °C to give an
orange solid. The mother liquor was decanted, and the orange
powder was washed with petroleum ether and then extracted
with toluene (15 × 1 mL). The combined toluene extracts were
filtered through Celite to give an orange solution. The toluene
was removed in vacuo to give an orange powder (95 mg, 67%
yield). Recrystallization from toluene/petroleum ether gave
Cr ysta llogr a p h ic Str u ctu r a l Deter m in a tion . Suitable
crystals of 9‚0.5C5H12 and 11 were obtained from toluene/
petroleum ether at -25 °C. Crystal data and data collection
and refinement parameters are given in Table 3. A Siemens
P4 diffractometer equipped with a CCD detector was used. The
structures were solved using direct methods, completed by
subsequent difference Fourier syntheses, and refined by full-
matrix least-squares procedures. All non-hydrogen atoms were
refined anisotropically. The hydrogen atoms were treated as
idealized contributions. The pentane solvent molecule in 9‚

3214 Organometallics, Vol. 21, No. 15, 2002
Zhuravel et al.
0.5C5H12 is disordered over two inversion centers and was
refined with isotropic thermal parameters. All software and
sources of the scattering factors are contained in the SHELXTL
(5.10) program library (G. Sheldrick, Siemens XRD, Madison,
WI).
Va r ia ble-Tem p er a tu r e NMR Da ta . Spectra were ob-
tained on a Varian 500 MHz NMR spectrometer. The reported
temperatures were calibrated from the chemical shift differ-
ence of the signals in the 1H NMR spectrum of a standard
sample of methanol (temperatures <20 °C) or ethylene gly-
col (temperatures >20 °C). The uncertainty in the ∆Gq(Tc)
values was estimated on the basis of the assumption that there
is an error of (10 °C in the determination of the coalescence
temperature.
Ack n ow led gm en t. We thank the NSF, DuPont, and
Union Carbide (Innovation Recognition Award) for
support and the Department of Education for a GAANN
fellowship for M.A.Z. The University of Delaware ac-
knowledges the NSF (Grant No. CHE-9628768) for
their support of the purchase of the CCD-based diffrac-
tometer.
Su p p or tin g In for m a tion Ava ila ble: Tables giving de-
tails of the X-ray crystal structure determinations for 9‚
0.5C5H12 and 11. This material is available free of charge via
the Internet at http://pubs.acs.org.
OM020249K