Structural and electronic impact of fluorine in the ortho positions of triphenylphosphine and 1,2-bis(diphenylphosphino)ethane; a comparison of 2,6-difluorophenyl- With pentafluorophenylphosphines

Article abstract of DOI:10.1039/a907759f

The new fluorine-containing phosphines PPh₂(C₆H₃F₂-2,6) I and PPh(C₆H₃F₂-2,6)₂ II were synthesized in high yield from C₆H₃BrF₂-2,6 and PPh₂Cl or PPhCl₂. Phosphines I, II and the previously reported P(C₆H₃F₂-2,6)₃ III have been structurally characterized by single-crystal X-ray diffraction. A range of transition metal complexes of I-III and the diphosphine (C₆H₃F₂-2,6)₂PCH₂CH ₂P(C₆H₃F₂-2,6)₂ have been prepared and their spectroscopic properties compared with those of the analogous complexes of the pentafluorophenylphosphines PPh_x(C₆F₅)_3-x(x = 0-2) and the diphosphine (C₆F₅)₂PCH₂CH₂P(C ₆F₅)₂. The structures of trans-[PtCl₂(PEt₃){PPh_x(C₆H ₃F₂-2,6)_3-x}] (x = 2,1 or 0), trans-[MCl(CO){PPh(C₆H₃F₂-2,6) ₂}₂] (M = Rh or Ir), trans-[IrCl{(CO){P(C₆H₃F₂-2,6) ₃}₂] and trans-[PtCl₂{PPh-(C₆H₃F₂-2,6) ₂}₂] have been determined by single-crystal X-ray diffraction. The spectroscopic and structural data indicate that the 2,6-difluorophenylphosphines are more basic than the analogous pentafluorophenylphosphines and exert a similar or slightly smaller steric influence. The Royal Society of Chemistry 2000.

Full text of DOI:10.1039/a907759f

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Structural and electronic impact of fluorine in the ortho positions
of triphenylphosphine and 1,2-bis(diphenylphosphino)ethane;
a comparison of 2,6-difluorophenyl- with pentafluorophenyl-
phosphines
Christopher Corcoran,a John Fawcett,a Steffi Friedrichs,a John H. Holloway,a Eric G. Hope,a
David R. Russell,a Graham C. Saunders*b and Alison M. Stuarta
a Department of Chemistry, University of Leicester, Leicester, UK LE1 7RH
b School of Chemistry, The Queen’s University of Belfast, David Keir Building, Belfast,
UK BT9 5AG. E-mail: g.saunders@qub.ac.uk
Received 27th September 1999, Accepted 16th November 1999
The new fluorine-containing phosphines PPh2(C6H3F2-2,6) I and PPh(C6H3F2-2,6)2 II were synthesized in high yield
from C6H3BrF2-2,6 and PPh2Cl or PPhCl2. Phosphines I, II and the previously reported P(C6H3F2-2,6)3 III have
been structurally characterized by single-crystal X-ray diffraction. A range of transition metal complexes of I–III
and the diphosphine (C6H3F2-2,6)2PCH2CH2P(C6H3F2-2,6)2 have been prepared and their spectroscopic properties
compared with those of the analogous complexes of the pentafluorophenylphosphines PPhx(C6F5)3 Ϫ x (x = 0–2) and
the diphosphine (C6F5)2PCH2CH2P(C6F5)2. The structures of trans-[PtCl2(PEt3){PPhx(C6H3F2-2,6)3 Ϫ x}] (x = 2, 1
or 0), trans-[MCl(CO){PPh(C6H3F2-2,6)2}2] (M = Rh or Ir), trans-[IrCl(CO){P(C6H3F2-2,6)3}2] and trans-[PtCl2{PPh-
(C6H3F2-2,6)2}2] have been determined by single-crystal X-ray diffraction. The spectroscopic and structural data
indicate that the 2,6-difluorophenylphosphines are more basic than the analogous pentafluorophenylphosphines
and exert a similar or slightly smaller steric influence.
The σ-withdrawing property of fluorine and its larger size com-
Results and discussion
Synthesis, characterization and structures of phosphines I, II and
III
pared with hydrogen (van der Waals radius 1.47 cf. 1.20 Å)1 are
expected to exert a profound influence on phosphorus() lig-
ands and their transition metal complexes when fluorine is
incorporated at strategic sites in the ligands. As part of our
project into studying and exploiting these effects we have
investigated complexes of the polyfluorinated phenylphos-
phines P(C6F5)3,2–5 PPh(C6F5)2,2,4,5 PPh2(C6F5)2,4,5 and
(C6F5)2PCH2CH2P(C6F5)2 (dfppe).2,5,6 We, and others,7–23 have
found that these ligands are more bulky and less basic than
their perprotio analogues and that complexes of these ligands
can possess chemical, structural and spectroscopic properties
which are significantly different to those of complexes of the
analogous phosphines PPh3 and dppe. We were interested in
extending our study to phosphines containing the 2,6-difluoro-
phenyl group, PPhx(C6H3F2-2,6)3 Ϫ x (x = 2 I, 1 II, or 0 III) and
(C6H3F2-2,6)2PCH2CH2P(C6H3F2-2,6)2, IV. It is envisaged that
these phosphines would exhibit similar steric effects to the
pentafluorophenyl analogues, but would be more basic by vir-
tue of comprising only two fluorine atoms per phenyl group. It
is clear that perfluorination of only one phenyl ring of PPh3
leads to steric and electronic effects which cause significant
structural and chemical changes in the complexes. Also, com-
plexes and reactions of the perfluorinated phosphine P(C6F5)3
can be different to those of both PPh3 and PPh2(C6F5). Com-
plexes and reactions of PPh(C6F5)2, depending on the metal
and ancillary ligands, resemble those of either PPh2(C6F5), as in
the complexes [RhCl(CO){PPhx(C6F5)3 Ϫ x}2],2 or P(C6F5)3, as
in the lack of reaction with [{RhCl(µ-Cl)(η5-C5Me5)}2].5 Recent
studies have shown that, in reactions with [{MCl(µ-Cl)(η5-
C5Me5)}2] (M = Rh or Ir), IV displays differences to dfppe
which were ascribed to both electronic and small steric differ-
ences between the diphosphine ligands.24 Here we report our
study of the new phosphines I and II, together with III, which
has been reported previously,9 but for which very few complexes
are known, and the recently synthesized diphosphine IV.24
Addition of PPh2Cl to [C6H3F2-2,6]ϪLiϩ, formed by treatment
of C6H3BrF2-2,6 with BunLi at Ϫ78 ЊC, afforded (2,6-difluoro-
phenyl)diphenylphosphine, I, in 70% yield. Bis(2,6-difluoro-
phenyl)phenylphosphine, II, and tris(2,6-difluorophenyl)-
phosphine, III, were prepared similarly from PPhCl2 and PCl3
in 49 and 87% yields respectively. Phosphines I–III were charac-
terized by elemental analysis, high resolution mass spec-
trometry and multinuclear NMR spectroscopies (Table 1).
Their 19F-{1H} NMR spectra exhibit doublets at ca. δ Ϫ100,
consistent with that of IV (δ Ϫ101.39).24 The 31P-{1H} NMR
spectra exhibit a triplet at δ Ϫ27.7, a quintet at δ Ϫ50.6 and a
septet at δ Ϫ78.2 respectively, comparable with those of
PPh2(C6F5) at δ Ϫ24.7, PPh(C6F5)2 at δ Ϫ45.1 and P(C6F5)3 at
δ Ϫ74.0. The values of |3J(PF)| for I, II and III are 3–6 Hz larger
than those for the respective pentafluorophenylphosphines25
and also larger than 30.1 Hz for IV.24
The structures of the phosphines I (Fig. 1), II (Fig. 2) and III
(Fig. 3) have been determined by single-crystal X-ray diffrac-
tion. The structure of IV has been reported.24 Bond lengths and
selected angles are given in Table 2. There are no significant
intermolecular interactions in the structures with the closest
contacts being greater than the sums of the van der Waals radii.
The structure of phosphine I is similar to that of PPh2(C6F5).20
In particular, the P–C (phenyl), P–C (fluorophenyl), PC–C and
C–F distances and the C–P–C, C–C(P)–C and P–C–CF angles
are the same within experimental error for the two compounds.
For one phenyl ring of I the P–C–C angles are identical to those
of the phenyl rings of PPh2(C6F5), which have one smaller angle
of ca. 116Њ and one of ca. 125Њ. The other phenyl ring of I has
both P–C–C angles close to 120Њ. The mean PC–C–F angle of I
[117.9(2)Њ] is slightly more acute than that of PPh2(C6F5)
[119.7(2)Њ].20 The structure of phosphine II is similar to that of
J. Chem. Soc., Dalton Trans., 2000, 161–172
This journal is © The Royal Society of Chemistry 2000
161

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Table 1 Analytical, mass spectral and NMR data for ligands I–III and complexes 1–12, 14 and 15
Analysis (%)a and m/z
Compound
NMRb
I C, 72.6 (72.5); H, 4.1 (4.4)
1H: 7.37 (11 H, m, Ph and Hp of C6H3F2), 6.91 (2 H, m, Hm of C6H3F2)d
m/z 298 (Mϩ), 220 ([M Ϫ C6H5 Ϫ H]ϩ), 201
([M Ϫ C6H5 Ϫ F Ϫ H]ϩ) (Found for Mϩ
298.07233. C18H13F2P requires 298.07230)c
13C-{1H}: 165.6 [d, 1J(CF) 250, Co of C6H3F2], 135.6 (m), 133.2 (m), 128.9 (m), 112.4 [d, 2J(CF) 23, Cm
of C6H3F2]d
19F-{1H}: Ϫ98.18 [d, 3J(PF) 42.2]d
31P-{1H}: Ϫ27.7 [t, 3J(PF) 42.2]d
II C, 64.6 (64.7); H, 3.1 (3.3)
1H: 7.54 (2 H, m, Hm of C6H5), 7.33 (5 H, m, Ho and Hp of C6H5 and Hp of C6H3F2), 6.85 [4 H, ddd,
3J(HmHp) ≈ 3J(HmF) 8.2, 4J(HmP) 2.2, Hm of C6H3F2]d
m/z 334 (Mϩ), 201 ([M Ϫ C6H3F2 Ϫ F Ϫ H]ϩ)
(Found for Mϩ 334.05336. C18H11F4P requires
334.05345)c
13C-{1H}: 163.3 [dm, 1J(CF) 249, Co of C6H3F2], 132.3 [dm, 1J(CP) 9, Cipso of C6H5], 131.7 [d, 2J(CP) 23,
Co of C6H5], 130.8 [tm, 3J(CF) 11, Cp of C6H3F2], 128.0 (s, Cp of C6H5), 127.2 [d, 3J(CP) 9, Cm of C6H5],
110.6 [dm, 2J(CF) 28, Cm of C6H3F2]d
19F-{1H}: Ϫ99.74 [d, 3J(PF) 36.2]d
31P-{1H}: Ϫ50.6 [quin, 3J(PF) 36.2]d
III C, 58.5 (58.4); H, 2.3 (2.5)
1H: 7.25 (3 H, m, Hp), 6.80 (6 H, m, Hm)d
m/z 370 (Mϩ), 351 ([M Ϫ F]ϩ), 257
([M Ϫ C6H3F2]ϩ) (Found for Mϩ 370.03460.
C18H9F6P requires 370.03461)c
13C-{1H}: 163.3 [dm, 1J(CoF) 250, Co], 130.8 [tm, 3J(CpF) 11, Cp], 111.6 [dm, 2J(CmF) 28, Cm]d
19F-{1H}: Ϫ101.43 [d, 3J(PF) 39.2]d
31P-{1H}: Ϫ78.2 [sept, 3J(PF) 39.2]d
1 C, 55.1 (55.4); H, 4.4 (4.7); Cl, 11.6 (11.7)
1H: 7.85 (4 H, m, Ho of C6H5), 7.26 (7 H, m, Hp of C6H3F2 and Hm and Hp of C6H5), 6.94 [2 H, dd,
3J(HmHp) ≈ 3J(HmF) 8.5, Hm of C6H3F2], 1.43 [15 H, d, 1J(PH) 3.5, CH3]d
19F-{1H}: Ϫ90.19 (s)d
m/z 571 ([M Ϫ Cl]ϩ), 536 ([M Ϫ 2Cl]ϩ)e
31P-{1H}: 15.8 [d, 1J(RhP) 148]d
2 C, 42.5 (42.3); H, 4.0 (4.1); Cl, 9.9 (10.4)
m/z 682 (Mϩ), 647 ([M Ϫ Cl]ϩ), 611
([M Ϫ 2Cl]ϩ)e
1H: 7.84 [4 H, dd, 3J(PH) 8.9, 3J(HoHm) 7.2, Ho of C6H5], 7.36 (7 H, m, Hp of C6H3F2 and Hm and Hp
of C6H5], 6.79 [2 H, ddd, 3J(HmHp) ≈ 3J(HmF) 8.5, 4J(PH) 3.4, Hm of C6H3F2], 1.88 (6 H, m, CH2), 1.16
[9 H, dtd, 3J(PH) 15.5, 3J(HH) 7.6, 5J(PH) 1.6, CH3]f
19F-{1H}: Ϫ90.95 [dd, 3J(PF) 5.8, 5J(PF) 1.4]f
31P-{1H}: 14.6 [d, 2J(PP) 486, 1J(PtP) 2625, PEt3], 9.1 [dt, 2J(PP) 486, 3J(PF) 5.8, 1J(PtP) 2444,
PPh2(C6H3F2)]f
3 C, 40.8 (40.1); H, 3.7 (3.65)
m/z 718 (Mϩ), 683 ([M Ϫ Cl]ϩ)e
1H: 7.75 [2 H, dd, 3J(PH) 12.2, 3J(HoHm) 7.6, Ho of C6H5], 7.34 (5 H, m, Hp of C6H3F2 and Hm and Hp
of C6H5], 6.85 [4 H, ddd, 3J(HmHp) ≈ 3J(HmF) 8.4, 4J(PH) 3.1, Hm of C6H3F2], 1.83 (6 H, m, CH2), 1.09
[9 H, dt, 3J(PH) 16.8, 3J(HH) 7.7, CH3]f
19F-{1H}: Ϫ95.58 [d, 3J(PF) 7.4]f
2
1
2
3
1
31P-{1H}: 10.5 [d, J(PP) 504, J(PtP) 2756, PEt3], Ϫ5.8 [dquin, J(PP) 504, J(PF) 7.3, J(PtP) 2374,
PPh(C6H3F2)2]f
4 C, 38.3 (38.2); H, 2.8 (3.2)
m/z 754 (Mϩ), 719 ([M Ϫ Cl]ϩ), 683
([M Ϫ 2Cl]ϩ)e
1H: 7.50 [3 H, tt, 3J(HpHm) 8.4, 4J(HpF) 6.2, Hp], 6.79 [6 H, ddd, 3J(HmHp) ≈ 3J(HmF) 8.6, 4J(PHm) 3.4,
Hm], 1.93 (6 H, m, CH2), 1.19 [9 H, dt, 3J(PH) 17.1, 3J(HH) 7.6, CH3]f
19F-{1H}: (293 K) Ϫ96.69 (br s);f (223 K) Ϫ93.78 [d, 3J(PF) 30.0], Ϫ98.79 (s), Ϫ101.31 (s)f
31P-{1H}: 16.3 [d, 2J(PP) 526, 1J(PtP) 2847, PEt3], Ϫ22.2 [dsept, 2J(PP) 526, 3J(PF) 9, 1J(PtP) 2352,
P(C6H3F2)3]f
5 C, 59.6 (58.3); H, 4.5 (4.3); Cl, 3.7 (4.7)
m/z 734 ([M Ϫ CO Ϫ H]ϩ), 728 ([M Ϫ Cl]ϩ),
699 ([M Ϫ CO Ϫ Cl Ϫ H]ϩ)e
1H: 7.89 [8 H, dd, 3J(HoHm) 6.3, 3J(PH) 6.0, Ho of C6H5], 7.39 [14 H, m, Hp of C6H3F2 and Hm and Hp of
C6H5], 6.84 [4 H, dd, 3J(HmHp) ≈ 3J(HmF) 8.5, Hm of C6H3F2]d
13C-{1H}: 187.7 [dm, 1J(RhC) 80, CO]d
19F-{1H}: Ϫ94.96 [vt, ¹|3J(PF) ϩ 5J(PF)| 5.6]d
¯
²
31P-{1H}: 18.7 [A part of AAЈM2MЈ2X spectrum, 1J(RhP) 133]d
3
6 C, 52.7 (53.3); H, 2.4 (2.7)
1H: 7.79 [4 H, dd, J(HoHm) ≈ 3J(HP) 6.8, Ho of C6H5], 7.31 (10 H, m, Hm and Hp of C6H5 and Hp of
m/z 834 ([M Ϫ H]ϩ), 799 ([M Ϫ H Ϫ Cl]ϩ),
771 ([M Ϫ CO Ϫ H Ϫ Cl]ϩ)e
C6H3F2), 6.80 [8 H, dd, 3J(HmHp) ≈ 3J(HmF) 8.8, Hm of C6H3F2]f
19F-{1H}: Ϫ95.96 [vt, ¹|3J(PF) ϩ 5J(PF)| 6.3]f
¯
²
31P-{1H}: 0.4 [A part of AAЈM4MЈ4X spectrum, 1J(RhP) 137]f
1H: 7.32 (6 H, m, Hp), 6.97 [12 H, dd, 3J(HmHp) ≈ 3J(HmF) 9.1, Hm]d
19F-{1H}: Ϫ96.76 (br s);d (373 K) Ϫ95.39 [vt, ¹|3J(PF) ϩ 5J(PF)| 8.2]g
7 C, 49.6 (49.0); H, 2.0 (2.0)
m/z 906 (M ϩ), 878 ([M Ϫ CO]ϩ), 871
([M Ϫ Cl]ϩ), 843 ([M Ϫ CO Ϫ Cl]ϩ)e
8 C, 51.4 (52.15); H, 3.1 (3.1)
¯
²
31P-{1H}: Ϫ28.2 [A part of AAЈM6MЈ6X spectrum, 1J(RhP) 144]d
1H: 7.89 [8 H, dd, 3J(HoHm) ≈ 3J(PHo) 6.2, Ho of C6H5], 7.39 [14 H, m, Hp of C6H3F2 and Hm and Hp of
C6H5], 6.81 [4 H, ddm, 3J(HmHp) ≈ 3J(HF) 8.5, Hm of C6H3F2]f
m/z 852 (M ϩ), 817 ([M Ϫ Cl]ϩ), 787
([M Ϫ CO Ϫ Cl Ϫ 2H]ϩ)e
19F-{1H}: Ϫ95.01[vt, ¹|3J(PF) ϩ 5J(PF)| 2.5]f
¯
²
31P-{1H}: 18.0 [A part of AAЈM2MЈ2 spectrum]f
3
9 C, 47.15 (48.1); H, 2.2 (2.4)
m/z 924 (M ϩ), 889 ([M Ϫ Cl]ϩ), 859
([M Ϫ CO Ϫ Cl Ϫ 2H]ϩ)e
1H: 7.82 [4 H, dd, J(HoHm) ≈ 3J(HP) 6.8, Ho of C6H5], 7.31 (10 H, m, Hm and Hp of C6H5 and Hp of
C6H3F2), 6.81 [8 H, dd, 3J(HmHp) ≈ 3J(HmF) 8.6, Hm of C6H3F2]f
19F-{1H}: Ϫ95.73 [vt, ¹|3J(PF) ϩ 5J(PF)| 3.3]f
¯
²
31P-{1H}: Ϫ5.3 [A part of AAЈM4MЈ4 spectrum]f
10 C, 43.9 (44.6); H, 1.7 (1.8)
1H: 7.32 [6 H, tt, 3J(HmHp) 8.3, 4J(HF) 6.1, Hp], 6.79 [12 H, ddm, 3J(HmHp) ≈ 3J(HmF) 8.7, Hm]f
m/z 995 ([M Ϫ H]ϩ), 967 ([M Ϫ H Ϫ CO]ϩ),
960 ([M Ϫ Cl]ϩ), 932 ([M Ϫ CO Ϫ Cl]ϩ)e
11 C, 50.1 (50.05); H, 2.8 (3.0)
m/z 862 (Mϩ), 827 ([M Ϫ Cl]ϩ), 791
([M Ϫ 2Cl]ϩ)
19F-{1H}: (293 K) Ϫ97.01 (br s);f (373 K) Ϫ97.01 [vt, ¹|3J(PF) ϩ 5J(PF)| 5.0]g
¯
²
31P-{1H}: Ϫ33.4 [A part of AAЈM6MЈ6 spectrum]f
1H: 7.88 [8 H, dd, 3J(HoHm) ≈ 3J(PH) 6.4, Ho of C6H5], 7.38 [14 H, m, Hp of C6H3F2 and Hm and Hp of
C6H5], 6.80 [4 H, dd, 3J(HmHp) ≈ 3J(HmF) 8.5, Hm of C6H3F2]d
19F-{1H}: Ϫ95.19 [vt, ¹|3J(PF) ϩ 5J(PF)| 3.9]d
¯
²
31P-{1H}: 8.5 [A part of AAЈM2MЈ2 spectrum, 1J(PtP) 2754]d
1H: 7.79 (4 H, m, Ho of C6H5), 7.38 (10 H, m, Hm and Hp of C6H5 and Hp of C6H3F2), 6.84 [8 H, dd,
3J(HmHp) ≈ 3J(HmF) 8.4, Hm of C6H3F2]d
12 C, 45.6 (46.3); H, 1.9 (2.4)
m/z 934 (Mϩ), 899 ([M Ϫ Cl]ϩ), 862
([M Ϫ 2Cl]ϩ)
19F-{1H}: Ϫ95.25 [vt, ¹|3J(PF) ϩ 5J(PF)| 4.2]d
¯
²
31P-{1H}: Ϫ8.9 [A part of AAЈM4MЈ4 spectrum, 1J(PtP) 2862]d
1H: 7.26 (4 H, m, Hp), 6.80 [8 H, ddm, 3J(HmHp) ≈ 3J(HmF) 8.5, Hm], 2.91 [4 H, d, 2J(PH) 19.2, CH2]d
19F-{1H}: Ϫ100.23 (X part of an AAЈX4XЈ4 spectrum)d
14 C, 48.2 (48.0); H, 1.9 (2.2)
m/z 751 (Mϩ), 723 ([M Ϫ CO]ϩ), 695
([M Ϫ 2CO]ϩ), 667 ([M Ϫ 3CO]ϩ), 640
([M Ϫ 4CO ϩ H]ϩ)e
31P-{1H}: 28.6 (A part of an AAЈX4XЈ4 spectrum)d
15h C, 38.5 (38.6); H, 1.8 (2.0); Cl, 8.3 (8.8)
m/z 807 (Mϩ, n = 1), 772 ([M Ϫ Cl]ϩ, n = 1),
737 ([M Ϫ 2Cl]ϩ, n = 1)e
a Required values are given in parentheses. b Recorded at 298 K, unless stated otherwise. Data given as chemical shift (δ) [relative intensity,
multiplicity, J/Hz, assignment], s = singlet, d = doublet, t = triplet, quin = quintet, vt = virtual triplet, sept = septet, m = multiplet, br denotes a signal
broadened due to a fluxional process. c EI. d Recorded in CDCl3. e Positive ion fast-atom bombardment with m-nitrobenzyl alcohol as matrix.
f Recorded in CD2Cl2. g Recorded in CD3CD5. h Insufficiently soluble for NMR study.
162
J. Chem. Soc., Dalton Trans., 2000, 161–172

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Table 2 Selected bond lengths (Å) and angles (Њ) with estimated
standard deviations (e.s.d.s) in parentheses for PPh2(C6H3F2-2,6) I,
PPh(C6H3F2-2,6)2 II and P(C6H3F2-2,6)3 III
I
II
III
P–C(11)
P–C(21)
P–C(31)
1.836(2)
1.832(3)
1.832(2)
1.392(3)
1.382(3)
1.390(3)
1.383(3)
1.381(3)
1.384(3)
1.352(3)
1.358(3)
—
1.832(3)
1.838(3)
1.823(3)
1.383(5)
1.384(5)
1.390(4)
1.389(4)
1.388(4)
1.401(4)
1.356(4)
1.363(4)
1.334(4)
1.313(4)
1.194(5)
1.345(5)
1.841(4)
1.837(4)
1.851(4)
1.392(5)
1.389(5)
1.399(6)
1.386(5)
1.392(5)
1.400(5)
1.357(4)
1.368(5)
1.358(5)
1.368(5)
1.362(4)
1.359(4)
C(11)–C(12)
C(11)–C(16)
C(21)–C(22)
C(21)–C(26)
C(31)–C(32)
C(31)–C(36)
C(12)–F(12)
C(16)–F(16)
C(22)–F(22)
C(26)–F(26)
C(32)–F(32)
C(36)–F(36)
—
—
—
C(11)–P–C(21)
C(11)–P–C(31)
C(21)–P–C(31)
P–C(11)–C(12)
P–C(11)–C(16)
P–C(21)–C(22)
P–C(21)–C(26)
P–C(31)–C(32)
103.42(10)
102.53(10)
102.84(10)
128.0(2)
118.7(2)
116.1(2)
126.0(2)
121.8(2)
119.9(2)
113.3(2)
117.9(2)
117.9(2)
118.0(2)
117.9(2)
—
100.73(13)
104.71(13)
105.41(12)
126.5(2)
119.3(3)
115.6(2)
128.8(2)
124.8(2)
117.7(2)
114.2(3)
115.6(3)
116.9(3)
117.9(3)
118.0(3)
119.0(3)
120.8(3)
127.8(4)
117.1(3)
105.8(2)
104.3(2)
99.6(2)
Fig. 1 Structure of PPh2(C6H3F2-2,6) I. Thermal ellipsoids are shown
at the 30% probability level.
129.9(3)
116.1(3)
126.5(3)
119.0(3)
117.3(3)
130.0(3)
113.7(4)
114.4(4)
112.6(3)
119.2(3)
116.8(3)
117.9(4)
118.2(4)
116.0(3)
118.8(3)
P–C(31)–C(36)
C(12)–C(11)–C(16)
C(22)–C(21)–C(26)
C(32)–C(31)–C(36)
C(11)–C(12)–F(12)
C(11)–C(16)–F(16)
C(21)–C(22)–F(22)
C(21)–C(26)–F(26)
C(31)–C(32)–F(32)
C(31)–C(32)–F(36)
—
—
—
Fig. 2 Structure of PPh(C6H3F2-2,6)2 II. Thermal ellipsoids are shown
at the 30% probability level. Bonds to disordered sites shown as dashed
lines.
I, but shows disorder of the phenyl ring and one of the difluoro-
phenyl rings, such that the fluorine atom sites F(22), F(26),
2
3
2
3
1
1
– – –
and occupan-
3
–
F(32) and F(36) were modelled with
,
,
3
cies respectively. The P–C distances are identical within experi-
mental error, similar to the case of I, but, unlike I, there are two
C–P–C angles of ca. 105Њ and one more acute angle of
100.73(13)Њ. Each phenyl ring exhibits a larger P–C–C angle of
>124Њ and a smaller P–C–C angle of <120Њ. The C–C(P)–C
angles are all considerably less than 120Њ, consistent with the
structures of I, III and IV. Four C–F distances are in the range
1.333(4) to 1.363(5) Å, consistent with those of other poly-
fluorophenylphosphines, but C(26)–F(26) and especially C(32)–
F(32) are anomalously short. This is probably as a result of the
disorder rather than a real effect. Similarly, four PC–C–F angles
lie in the range 117.1(3) to 119.0(3), whereas C(21)–C(26)–
F(26) and C(31)–C(32)–F(32) are anomalously large. The struc-
ture of phosphine III is similar to that of P(C6F5)3.17 The P–C,
PC–C and C–F bond lengths and C–P–C angles are identical
within experimental error for the two compounds and the three
sets of P–C–C and C–C(P)–C angles are similar. The PC–C–F
angles of III lie in the range 116.0(3) to 119.2(3)Њ with a mean
of 117.8(3)Њ and are more acute than those of P(C6F5)3, which
have a mean of 119.5(3)Њ.17 The more acute PC–C–F angles for
the difluorophenylphosphines I and III compared with the
pentafluorophenyl analogues are consistent with the more acute
Fig. 3 Structure of P(C6H3F2-2,6)3 III. Details as for Fig. 1.
PC–C–F angles of IV24 in comparison to those of dfppe.2
It may be presumed that the mean PC–C–F angle of all
P(C6H3F2-2,6) moieties is smaller than that of the analogous
P(C6F5) moieties.
Transition metal complexes of phosphines I, II and III
Treatment of the dimer [{RhCl(µ-Cl)(η5-C5Me5)}2] with I in
refluxing benzene afforded [RhCl2{PPh2(C6H3F2-2,6)}(η5-C5-
Me5)] 1 in high yield (Scheme 1). The values of δP and |1J(RhP)|
J. Chem. Soc., Dalton Trans., 2000, 161–172
163

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Fig. 4 Diagrammatic representations of the arrangements of the
phenyl rings of the PPhx(C6H3F2-2,6)3 Ϫ x ligands of (a) complex 4 in
solution at the low temperature limit, (b) 2 and (c) 3 and 4 (X = H or F)
in the solid state structures viewed along the Pt–P bond.
Scheme 1 (i) [{RhCl(µ-Cl)(η5-C5Me5)}2], C6H6, heat; (ii) [{PtCl(µ-Cl)-
(PEt3)}2], acetone, heat; (iii) M = Rh, [{Rh(µ-Cl)(CO)2}2], CH2Cl2, or
M = Ir, [{Ir(µ-Cl)(η2,ηЈ2-C8H12)}2], CH2Cl2, 1 atm CO, or M = Pt,
X = Cl, [PtCl2(NCMe)2], CH2Cl2, heat.
(Table 1) are similar to those of δP 18.8 and 149 Hz for the
analogous complex [RhCl2{PPh2(C6F5)}(η5-C5Me5)],5 and δP
7.9 and 144 Hz for [RhCl2(PPh3)(η5-C5Me5)].26 Phosphines II
and III failed to react with [{RhCl(µ-Cl)(η5-C5Me5)}2], con-
sistent with observations for PPh(C6F5)2 and P(C6F5)3.5 Pre-
sumably this is due to the greater bulk of these phosphines
compared to I and PPh2(C6F5).
Treatment of the dimer [{PtCl(µ-Cl)(PEt3)}2] with I, II or III
in acetone afforded the complexes trans-[PtCl2(PEt3){PPhx-
(C6H3F2-2,6)3 Ϫ x}] (x = 2 2, 1 3 or 0 4) in moderate yields
(Scheme 1). The trans geometries of these complexes are con-
firmed by the magnitudes of the phosphorus–phosphorus and
platinum–phosphorus couplings, |2J(PP)| and |1J(PtP)| (Table
1), which are similar to the respective values for the analogous
pentafluorophenylphosphine complexes trans-[PtCl2(PEt3)-
{PPhx(C6F5)3 Ϫ x}] (x = 0–2).4 The values of |1J(PtPPhx(C6H3-
F2)3 Ϫ x)| decrease and those of |1J(PtPEt3)| and |2J(PP)| increase
regularly as phenyl is substituted by difluorophenyl. In addi-
tion, the phosphorus–fluorine coupling is resolved, and at
298 K the phosphorus resonance assigned to the PPhx(C6H3F2-
2,6)3 Ϫ x ligand appears as a doublet of triplets for 2, a doublet
of quintets for 3 and a doublet of septets for 4. Further, the 19F-
{1H} NMR spectrum of 2 exhibits a doublet of doublets indi-
cating that the fluorine atoms are coupled to both phosphorus
atoms, but |5J(PF)| cannot be resolved in the 19F-{1H} NMR
spectrum of 3. In contrast, the 19F-{1H} NMR spectrum of 4,
recorded at 376.50 MHz and 298 K, exhibits a broad signal
suggestive of a fluxional process. On cooling to 223 K three
sharp signals of equal intensity are observed. These data are
consistent with restricted rotation about the P–C bonds, as
has been observed in trans-[PtCl2(PEt3){P(C6F5)3}].4 The three
signals occur as two singlets and a doublet with a phosphorus–
fluorine coupling, |3J(PF)|, of 30.0 Hz. The coupling is con-
firmed by the 31P-{1H} NMR spectrum at 223 K, which exhibits
a doublet of triplets for the P(C6H3F2-2,6)3 resonance. The low
temperature data are consistent with the conformation of the
P(C6H3F2-2,6)3 ligand depicted in Fig. 4(a). There is a unique
phenyl ring which lies perpendicular to the plane defined by the
Pt–P bond and respective P–C bond such that the fluorine
atoms are equivalent (Fa). The other two rings lie twisted to the
planes defined by the Pt–P bond and respective P–C bonds such
that there is a mirror plane through the phosphorus atom relat-
ing the two rings. The two fluorine atoms of each of these rings
are non-equivalent, but are equivalent to the fluorine atoms
of the other ring (Fb and Fc). This conformation is similar
to that adopted by the P(C6F5)3 ligand of trans-[PtCl2(PEt3)-
{P(C6F5)3}] at low temperature in solution.4 Since all the P–C–
Fig. 5 Structure of trans-[PtCl2(PEt3){PPh2(C6H3F2-2,6)}] 2. Thermal
ellipsoids are shown at the 30% probability level. Hydrogen atoms are
omitted for clarity.
Fig. 6 Structure of trans-[PtCl2(PEt3){PPh(C6H3F2-2,6)2}] 3. Thermal
ellipsoids are shown at the 30% probability level. Hydrogen atoms are
omitted for clarity. Bonds to disordered sites shown as dashed lines.
C–F torsion angles must be ca. 0Њ, it is not clear as to why only
one pair of fluorine atoms shows coupling to the phosphorus
atoms, or as to which pair of fluorine atoms it is.
The structures of complexes 2 (Fig. 5), 3 (Fig. 6) and 4 (Fig.
7) were determined by single-crystal X-ray diffraction. The
structure of 3 shows disorder of the phenyl and both difluoro-
2
–
phenyl rings, which was modelled with occupancy of all the
3
fluorine atom sites. Selected bond lengths and angles for 2–4
are given in Table 3. The structures of 2 and 4 possess no inter-
164
J. Chem. Soc., Dalton Trans., 2000, 161–172

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Table 3 Selected bond lengths (Å) and bond and torsion angles (Њ)
with e.s.d.s in parentheses for trans-[PtCl2(PEt3){PPh2(C6H3F2-2,6)}] 2,
trans-[PtCl2(PEt3){PPh(C6H3F2-2,6)2}]
{P(C6H3F2-2,6)3}] 4
3
and trans-[PtCl2(PEt3)-
2
3
4
Pt–P(1)
Pt–P(2)
Pt–Cl(1)
Pt–Cl(2)
P(2)–C(11)
P(2)–C(21)
P(2)–C(31)
C(12)–F(12)
C(16)–F(16)
C(22)–F(22)
C(26)–F(26)
C(32)–F(32)
C(36)–F(36)
2.293(2)
2.330(2)
2.320(2)
2.287(3)
1.822(10)
1.815(9)
1.829(9)
1.355(11)
1.352(11)
—
2.293(3)
2.288(2)
2.328(2)
2.308(2)
2.303(2)
1.821(6)
1.834(6)
1.828(6)
1.344(8)
1.348(8)
1.346(8)
1.348(8)
1.363(7)
1.364(8)
2.320(3)
2.308(3)
2.312(3)
1.832(11)
1.829(13)
1.832(11)
1.36(2)
1.369(14)
1.35(2)
1.35(2)
—
—
—
1.32(2)
1.34(2)
P(1)–Pt–P(2)
P(1)–Pt–Cl(1)
P(1)–Pt–Cl(2)
P(2)–Pt–Cl(1)
P(2)–Pt–Cl(2)
Cl(1)–Pt–Cl(2)
Pt–P(2)–C(11)
Pt–P(2)–C(21)
175.80(10)
90.57(11)
86.57(11)
91.10(9)
91.88(9)
176.62(10)
111.5(3)
114.1(3)
115.8(3)
119.9(7)
126.5(7)
122.8(7)
118.1(7)
119.1(7)
121.4(7)
116.9(8)
118.4(8)
—
169.79(11)
93.34(12)
86.41(12)
93.41(11)
86.66(11)
178.66(11)
120.0(4)
119.6(4)
103.2(4)
127.6(9)
117.8(8)
169.97(6)
86.91(7)
93.29(7)
86.01(6)
93.66(6)
178.91(7)
120.1(2)
103.0(2)
119.5(2)
123.9(5)
120.8(5)
126.2(5)
117.5(5)
117.2(5)
129.0(5)
119.4(6)
117.8(6)
120.4(6)
117.5(6)
117.0(6)
119.0(6)
Fig. 7 Structure of trans-[PtCl2(PEt3){P(C6H3F2-2,6)3}] 4. Details as
for Fig. 5.
molecular contacts less than the sums of the van der Waals
radii, but that of 3 contains one H ؒ ؒ ؒ F distance of 2.367 Å.
The structural determinations confirm the trans square-planar
geometry of the complexes. For 2–4 and trans-[PtCl2(PEt3)-
{PPh2(C6F5)}]4 the Pt–PPhx(C6H3F2-2,6)3 Ϫ x distances are the
same within experimental error, as are the Pt–PEt3 distances,
which are ca. 0.04 Å shorter. The Pt–Cl bond lengths of 3 and
4 are the same within experimental error, whereas those of 2
differ by ca. 0.03 Å, but with a mean value [2.304(3) Å] similar
to those for 3 [2.310(3) Å], 4 [2.305(2) Å] and trans-[PtCl2-
(PEt3){PPh2(C6F5)}] [2.309(2) Å].4 The P–C6H3F2 and P–C6H5
bond lengths of 2, 3 and 4 are the same within experimental
error. This is consistent with the P–C6F5 and P–C6H5 bond
lengths of the pentafluorophenylphosphine ligand in trans-
[PtCl2(PEt3){PPh2(C6F5)}],4 but in contrast to those of trans-
[PtMe(PEt3){PPh2(C6F5)}(OC6F4PPh2-2)] in which the P–C6F5
distance is significantly longer than the P–C6H5 distances.19 The
complexes differ in the angles about the phosphorus atoms of
the triarylphosphine ligands. The Pt–P–C6H5 angles of 2 are the
same within experimental error and the Pt–P–C6H3F2 angle is
ca. 2.5Њ smaller. In contrast, the Pt–P–C angles of 3 and 4 show
a great variation with two of ca. 120Њ and one of ca. 103Њ. The
conformation of the PPh2(C6H3F2-2,6) ligand in 2 is similar to
that of PPh2(C6F5) in trans-[PtCl2(PEt3){PPh2(C6F5)}].4 The di-
fluorinated phenyl ring of complex 2 lies perpendicular to the
plane defined by the Pt–P bond and respective P–C6H3F2 bonds
[i.e. the absolute Pt–P(2)–C(11)–C torsion angles are close to
90Њ] and the two phenyl rings lie twisted by ca. 25Њ from
coplanar with the planes defined by the respective Pt–P and
P–C bonds [i.e. the absolute Pt–P–C–C torsion angles are close
to 25 and 155Њ for each ring] (Fig. 4b). This conformation
resembles that of the P(C6H3F2-2,6)3 ligand of 4 in solution. In
contrast to the PPh2(C6H3F2-2,6) ligand of 2, one aryl ring of
the PPh(C6H3F2-2,6)2 ligand of 3 lies almost coplanar to the
plane defined by the respective Pt–P and P–C bonds [i.e. the
absolute Pt–P(2)–C(21)–C torsion angles are close to 180 and
0Њ] and the other two aryl rings lie twisted by ca. 30Њ from the
perpendicular to the plane defined by the respective Pt–P and
P–C bonds [i.e. the absolute Pt–P(2)–C(11)–C and Pt–P(2)–
C(31)–C torsion angles are close to 120 and 60Њ] (Fig. 4c). The
conformation of the P(C6H3F2-2,6)3 ligand of 4 in the solid
state is similar to that of the PPh(C6H3F2-2,6)2 ligand of 3 and
is similar to those adopted by the P(C6F5)3 ligands in the solid
state structures of the square-planar complexes trans-[IrBr(CO)-
{P(C6F5)3}2],3 trans-[PtX2{P(C6F5)3}2] (X = Cl13 or I12) and
trans-[PdCl2{P(C6F5)3}2].14 This conformation is inconsistent
with the low temperature 19F-{1H} NMR spectrum of 4 and
Pt–P(2)–C(31)
P(2)–C(11)–C(12)
P(2)–C(11)–C(16)
P(2)–C(21)–C(22)
P(2)–C(21)–C(26)
P(2)–C(31)–C(32)
P(2)–C(31)–C(36)
C(11)–C(12)–F(12)
C(11)–C(16)–F(16)
C(21)–C(22)–F(22)
C(21)–C(26)–F(26)
C(31)–C(32)–F(32)
C(31)–C(36)–F(36)
120.0(9)
123.7(10)
124.7(9)
117.7(9)
118.6(10)
117.9(10)
120.5(12)
119.3(12)
125.2(12)
117.6(11)
—
—
—
Cl(2)–Pt–P(2)–C(11)
Cl(2)–Pt–P(2)–C(21)
Cl(2)–Pt–P(2)–C(31)
Pt–P(2)–C(11)–C(12)
Pt–P(2)–C(11)–C(16)
Pt–P(2)–C(21)–C(22)
Pt–P(2)–C(21)–C(26)
Pt–P(2)–C(31)–C(32)
Pt–P(2)–C(31)–C(36)
Ϫ7.3(3)
Ϫ128.0(3)
111.1(3)
71.0(8)
96.8(8)
160.7(7)
20.7(9)
176.2(4)
55.5(4)
Ϫ124.7(2)
116.5(2)
Ϫ3.4(2)
Ϫ62.8(4)
119.2(1.1)
Ϫ61.2(1.1)
Ϫ171.7(8)
11.5(1.1)
106.3(1.0)
Ϫ62.4(9)
14.2(6)
Ϫ170.8(4)
105.2(6)
Ϫ62.1(5)
Ϫ61.9(6)
120.1(6)
31.0(8)
152.6(7)
indicates that the conformations adopted by the P(C6H3F2-2,6)3
ligand of 4 in the solid state and at low temperature in solution
are different. This supports the same conclusion drawn for the
conformations of P(C6F5)3 in square-planar complexes.4 The
mean PC–C–F angle of 2 is 117.7(8)Њ, which may be compared
with that of the pentafluorophenylphosphine analogue trans-
[PtCl2(PEt3){PPh2(C6F5)}] [120.3(8)Њ].4 The PC–C–F angles of
2 and 4 [mean 118.5(6)Њ] are similar to those of I and III respect-
ively. The PC–C–F angles of 3 and II are also similar, but both
contain an anomalously large angle of greater than 125Њ, which
may be a consequence of the disorder exhibited in both
structures.
Phosphines I, II and III reacted with [{Rh(µ-Cl)(CO)2}2] to
form the yellow complexes trans-[RhCl(CO){PPhx(C6H3F2-
2,6)3 Ϫ x}2] (x = 2 5, 1 6 or 0 7) in high yield (Scheme 1). The
compounds were characterized by elemental analysis, mass
spectrometry and multinuclear NMR spectroscopies (Table 1).
The trans geometry of the complexes was established by 31P
NMR spectroscopy, which showed a single resonance for each.
The 31P-{1H} and 19F-{1H} NMR spectra are those of AAЈMn-
MЈnX (n = 2 5, 4 6 or 6 7) spin systems. The 31P-{1H} NMR
spectra exhibit resonances centred at δ 18.7, 0.4 and Ϫ28.2
respectively similar to those of the respective pentafluorophenyl
J. Chem. Soc., Dalton Trans., 2000, 161–172
165

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᎐
Table 4 ν(C᎐O) for trans-[MCl(CO)(PR3)2] complexes
᎐
Ϫ1
᎐
ν(C᎐O)/cm
᎐
Phosphine
M = Rh
M = Ir
PPh3
1961a
1951b
1960
P(C6H4F-4)3
PPh2(C6H3F2-2,6) I
PPh2(C6F5)
PPh(C6H3F2-2,6)2 II
PPh(C6F5)2
P(C6H3F2-2,6)3 III
P(C6F5)3
1984c
1967 (5)d
1982e
1953 (8)d
—
1961 (6)d
2002e
1952 (9)d
—
1965 (7)d
1952 (10)d
2008e
1996f
a Ref. 27. b Ref. 28. c Ref. 29. d Resolution 4 cmϪ1
.
e Ref. 2. f Ref. 3.
analogues (δ 24.0, 3.4 and Ϫ25.8).2 The magnitudes of the
rhodium–phosphorus couplings, |1J(RhP)|, were calculated to
be 133, 137 and 144 Hz respectively, which can be compared to
the values of 133, 136 and 155 for the respective pentafluoro-
phenyl analogues.2 It is noted that the values of |1J(RhP)| for
5–7 increase slightly with the number of difluorophenyl groups,
whereas |1J(RhP)| for trans-[RhCl(CO){P(C6F5)3}2] is signifi-
cantly larger than for trans-[RhCl(CO){PPhx(C6F5)3 Ϫ x}2] (x =
1 or 2). The 19F-{1H} NMR resonances of 5 and 6 appear as
virtual triplets. The 19F-{1H} NMR spectrum of 7, recorded in
CD2Cl2 at a spectrometer frequency of 376.50 MHz, exhibits a
broad resonance indicative of a fluxional process. On cooling
the resonance broadens and at 213 K the spectrum exhibits a
triplet at δF Ϫ94.45 with a coupling, |3J(PF)|, of 27.6 Hz, and a
singlet at δF Ϫ103.59. On further cooling to 188 K the spectrum
exhibits four broad resonances at ca. δF Ϫ93.3, Ϫ95.4, Ϫ98.5
and Ϫ103.2 in addition to the triplet and singlet resonances.
This is consistent with the observation of six resonances,
assigned to ortho fluorine atoms, in the low temperature 19F
NMR spectrum of the bis{tris(pentafluorophenyl)phosphine}
complex trans-[PtCl2{P(C6F5)3}2].11 The 19F NMR behaviour of
7 was also investigated at higher temperature in C6D5CD3. On
warming, the broad resonance sharpens and two doublet
resonances arise and grow in intensity. At 373 K the original
broad resonance appears as a virtual triplet at δF Ϫ95.39 with
an apparent coupling, ¹|3J(PF) ϩ 5J(PF)|, of 8.2 Hz. This reson-
Fig. 8 Structure of trans-[RhCl(CO){PPh(C6H3F2-2,6)2}2], 6. Details
as for Fig. 6.
no centre of symmetry.30 The Rh–Cl distance is longer and the
Rh–P distances shorter for 6 than for trans-[RhCl(CO)(PPh3)2],
᎐
but the Rh–C and C᎐O distances for the two compounds are
᎐
identical within experimental error, consistent with the IR spec-
tral data. Compound 6 possesses two Rh–P–C angles of 117–
120Њ and one of ca. 104Њ. In contrast, the Rh–P–C angles of
trans-[RhCl(CO)(PPh3)2] lie in the range 109.8(1) to 117.1(1)Њ.
The PC–C–F angles of 6 are similar to those of phosphine II,
including one anomalously large angle of 125.1(6)Њ.
The iridium complexes trans-[IrCl(CO){PPhx(C6H3F2-
2,6)3 Ϫ x}2] (x = 2 8, 1 9 or 0 10) were prepared in high yield by
treatment of [{Ir(µ-Cl)(η2,η2Ј-C8H12)}2] with four equivalents
of I, II or III respectively under an atmosphere of CO and
isolated as yellow crystalline solids. Complex 10 was also pre-
pared in low yield by treatment of IrCl3ؒxH2O with III in reflux-
ing 2-methoxyethanol. The compounds were characterized by
elemental analysis, mass spectrometry and multinuclear NMR
spectroscopies (Table 1). The trans geometry of the complexes
was established by 31P NMR spectroscopy, which showed a
single resonance for each. Similarly to 5–7, the complexes 8–10
exhibit second order 31P-{1H} and 19F-{1H} NMR spectra con-
sistent with AAЈXnXЈn (n = 2 8, 4 9 or 6 10) spin systems. The
31P-{1H} NMR spectrum of 10 exhibits a resonance at δ Ϫ33.4
consistent with that of trans-[IrCl(CO){P(C6F5)3}2] (δ Ϫ31.3).3
The 19F-{1H} NMR resonances of 8 and 9 appear as virtual
triplets, whereas that of 10 is a broad indicative of a fluxional
process, presumably hindered rotation about the P–C bonds as
for 4 and 7. On cooling a solution of 10 in CD2Cl2 to 213 K the
19F-{1H} NMR spectrum exhibits an unresolved triplet reson-
ance at δF Ϫ94.45 and a singlet at δF Ϫ103.51. This is consistent
with the spectrum observed for 7 at 203 K. At the high temper-
ature limit the 19F-{1H} NMR spectrum of 10 appears as a
virtual triplet with ¹|3J(PF) ϩ 5J(PF)| = 5.0 Hz. The values of
¯
²
ance is consistent with those of 5 and 6 at ambient temperature.
The two doublet resonances are centred at δF Ϫ95.89 and
Ϫ101.04 with couplings, |3J(PF)|, of 15.6 and 40.3 Hz respect-
ively with a ratio of integration of ca. 2:1. The latter resonance
is assigned to III by comparison of the data with those obtained
for the phosphine in CDCl3 at 298 K (Table 1). The identity of
the compound giving rise to the former resonance is unknown,
but may arise due to the loss of III from 7. Unfortunately com-
plex 7 is not sufficiently soluble in toluene to allow the 31P
NMR spectrum to be recorded at 373 K.
᎐
The values of ν(C᎐O) for complexes 5 to 7 and, for com-
᎐
¯
²
᎐
parison, those for other trans-[RhCl(CO)(PR3)2] complexes are
presented in Table 4. The structure of 6 (Fig. 8) has been deter-
mined by single-crystal X-ray diffraction. Selected bond dis-
tances and angles are given in Table 5. There are two short
intermolecular contacts in the structure F(32) ؒ ؒ ؒ Cl(1Ј) (3.038
Å) and F(32) ؒ ؒ ؒ F(36Ј) (2.561 Å). The rhodium atom lies on a
crystallographic centre of symmetry such that the carbonyl and
chloride ligands are disordered. The PPh(C6H3F2-2,6)2 ligands
are identical and show disorder of the phenyl ring and one
difluorophenyl ring, which was modelled with 80% occupancy
of the fluorine atom sites F(22) and F(26) and 20% occupancy
of F(32) and F(36). The conformation of the PPh(C6H3F2-2,6)2
ligands relative to the P–Rh–P axis is similar to that of
PPh(C6H3F2-2,6)2 in 3 (i.e. absolute Cl–Rh–P–C torsion angles
of ca. 180, 60 and 60Њ, and absolute Rh–P–C–C torsion angles
of ca. 180, 0, 120, 60, 120 and 60Њ). The structure of 6 may be
compared to that of trans-[RhCl(CO)(PPh3)2], which possesses
ν(C᎐O) for complexes 8 to 10 and, for comparison, those for
᎐
other trans-[IrCl(CO)(PR3)2] complexes are presented in Table
᎐
4. It is apparent that ν(C᎐O) for the trans-[MCl(CO)(PAr ) ]
᎐
3
2
(M = Rh or Ir) complexes of the difluorophenylphosphines are
more comparable with those of [MCl(CO)(PPh3)2] than with
those of the pentafluorophenylphosphine complexes.
The structures of complexes 9 (Fig. 9) and 10 (Fig. 10) have
been determined by single-crystal X-ray diffraction. Selected
bond distances and angles are given in Table 5. Neither struc-
ture possesses significant intermolecular interactions. The irid-
ium atoms of both 9 and 10 lie on crystallographic centres of
symmetry giving rise to disorder between the carbonyl and
chloride ligands and P–Ir–P and Cl–Ir–C angles of 180Њ. This is
in contrast to the structures of trans-[IrX(CO){P(C6F5)3}2]
(X = Cl31 or Br3) in which there is no centre of symmetry and
no disorder, and the P–Ir–P and X–Ir–C angles are ca. 169.8
and 175.5Њ respectively. The PPh(C6H3F2-2,6)2 ligands of 9 also
166
J. Chem. Soc., Dalton Trans., 2000, 161–172

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Table 5 Selected bond lengths (Å) and bond and torsion angles (Њ) with e.s.d.s in parentheses for trans-[RhCl(CO){PPh(C6H3F2-2,6)2}2] 6, trans-
[IrCl(CO){PPh(C6H3F2-2,6)2}2] 9 and trans-[IrCl(CO){P(C6H3F2-2,6)3}2] 10
6
9
10
M–P
M–Cl
M–C
C–O
P–C
2.3100(13)
2.419(5)
1.759(14)
1.14(2)
1.831(4)
2.3045(13)
2.375(5)
1.84(3)
1.07(3)
1.825(5)
2.3025(12)
2.408(4)
1.783(12)
1.152(12)
1.827(5)
1.835(4)
1.826(5)
1.832(5)
1.836(4)
1.837(5)
1.835(5)
C–F
1.379(5), 1.337(5)
1.335(6), 1.340(5)
1.261(11), 1.337(12)
1.353(6), 1.344(7)
1.27, 1.37
1.42, 1.29
1.354(5), 1.370(5)
1.360(6), 1.359(5)
1.359(5), 1.350(5)
P–M–P
P–M–Cl
P–M–C
Cl–M–C
M–C–O
M–P–C
180.0
180.0
180.0
85.57(13), 94.43(13)
93.3(5), 86.7(5)
180.0
178.3(20)
119.58(14)
91.4(2), 88.6(2)
91.1(8), 88.9(8)
180.0
171.7(28)
119.7(2)
94.07(9), 85.93(9)
86.5(4), 93.5(4)
180.0
177(2)
119.3(2)
117.91(15)
118.7(2)
118.83(14)
104.26(14)
106.4(2)
103.4(2)
P–C–CF
127.4(3), 117.7(3)
122.3(3), 122.6(4)
125.8(3), 116.2(3)
116.6(4), 120.1(4)
117.5(4), 120.5(4)
118.8(6), 125.1(6)
124.0(4), 121.0(4)
123.1(3), 119.5(4)
117.9(3), 125.7(4)
118.6(4), 118.4(5)
119.9(5), 120.4(5)
118.7(5), 116.2(5)
118.4(3), 127.2(4)
124.0(4), 121.7(4)
118.3(3), 128.0(3)
119.2(4), 116.5(4)
117.3(4), 119.4(4)
116.8(4), 118.8(4)
C(P)–C–F
Cl–M–P–C
M–P–C–C
Ϫ60.58(22)
58.12(22)
Ϫ178.67(24)
Ϫ65.01(36), 104.31(40)
Ϫ168.54(31), 16.73(41)
Ϫ54.95(38), 125.14(37)
Ϫ93.89 (28)
145.65(28)
26.21(27)
Ϫ88.94(44), 82.52(42)
155.73(37), Ϫ31.33(49)
Ϫ148.25(38), 38.58 (45)
Ϫ64.64(20)
55.06(21)
177.34(21)
104.92(42), Ϫ65.16(39)
Ϫ167.28(31), 15.14(46)
Ϫ55.41(38), 124.92(37)
Fig. 9 Structure of trans-[IrCl(CO){PPh(C6H3F2-2,6)2}2], 9. Details as
for Fig. 6.
Fig. 10 Structure of trans-[IrCl(CO){P(C6H3F2-2,6)3}2], 10. Details as
for Fig. 5.
show disorder between the phenyl ring and one difluorophenyl
ring which was modelled by ¹ occupancy of the fluorine atom
Å].32 The Ir–C bond length of 10 is similar to that of trans-
[IrCl(CO)(PPh3)2], but significantly shorter than those of trans-
¯
²
᎐
sites F(22), F(26), F(32) and F(36). These ligands adopt a
conformation similar to that in complex 3, with one aryl ring
perpendicular to the plane defined by the Ir–P and respective
P–C bonds (i.e. Ir–P–C–C torsion angles of ca. 90 and Ϫ90Њ)
and the other two aryl rings twisted by ca. 30Њ from parallel
with the plane defined by the Ir–P and respective P–C bonds
(i.e. absolute Ir–P–C–C torsion angles of ca. 150 and 30Њ). The
P(C6H3F2-2,6)3 ligands of 10 adopt the same conformation as
in 4. The Ir–P distances of 9 and 10 are identical within experi-
mental error, consistent with the similarity of the M–P dis-
tances of the platinum complexes 2, 3 and 4. The Ir–Cl distance
of 10 is ca. 0.02 Å longer than those of 9, trans-[IrCl(CO)-
{P(C6F5)3}2] (2.369 Å) and trans-[IrCl(CO)(PPh3)2] [2.382(3)
[IrX(CO){P(C F ) } ] (X = Cl or Br, ca. 1.85 Å). The C᎐O bond
᎐
6
5 3 2
distance is similar to that of trans-[IrCl(CO)(PPh3)2] and ca. 0.1
Å longer than that of trans-[IrBr(CO){P(C6F5)3}2]. These
᎐
observations are consistent with the values of ν(C᎐O) for 10
᎐
and trans-[IrCl(CO)(PPh3)2] being similar and that for trans-
[IrBr(CO){P(C6F5)3}2] being ca. 40 cmϪ1 higher (Table 4). The
᎐
estimated standard deviations of the Ir–C and C᎐O bond dis-
᎐
tances of 9 are too large to permit comparison with those of
other trans-[IrCl(CO)(PR3)2] complexes. As for 6 and trans-
[IrX(CO){P(C6F5)3}2], the structures of 9 and 10 possess two
M–P–C angles of ca. 118Њ and one of ca. 105Њ. The more acute
nature of the PC–C–F angles of III compared to P(C6F5)3 is
manifested in complex 10, which has a mean PC–C–F angle of
J. Chem. Soc., Dalton Trans., 2000, 161–172
167

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Table 6 Selected bond lengths (Å) and bond and torsion angles (Њ) with e.s.d.s in parentheses for trans-[PtCl2{PPh(C6H3F2-2,6)2}2] 12
Pt–P
P–C
2.303(2)
Pt–Cl
C–F
2.302(2)
1.808(10)
1.819(10)
1.828(10)
1.28(3), 1.25(4)
1.362(10), 1.349(11)
1.336(12), 1.346(12)
P–Pt–P
P(1)–Pt–Cl(1)
Pt–P–C
180.0
85.60(8)
116.5(3)
105.0(3)
Cl–Pt–Cl
P(1)–Pt–Cl(1Ј)
P–C–CF
180.0
94.40(8)
126.5(9), 117.2(7)
117.0(8), 128.1(9)
122.3(8), 123.5(8)
119.5(3)
C(P)–C–F
116(2), 123(2)
117.9(9), 118.3(10)
120.5(10), 117.4(10)
Cl(1)–Pt–P(1)–C
178.61(40)
59.80(36)
Ϫ60.36(34)
Pt–P–C–C
55.98(77), Ϫ123.14 (87)
63.62(86), Ϫ105.86 (95)
Ϫ16.06(94), 169.69 (68)
118.0(4)Њ compared to 120.3Њ for trans-[IrCl(CO){P(C6F5)3}2].
The PC–C–F angles of 9 have a mean of 118.7(5)Њ, and in
contrast to the structures of II, 3 and 6 there is no anomalously
large angle in spite of the disorder.
Treatment of cis-[PtCl2(NCMe)2] with two equivalents of I,
II or III afforded the platinum complexes trans-[PtCl2{PPhx-
(C6H3F2-2,6)3 Ϫ x}2] (x = 2 11, 1 12 or 0 13) as pale yellow crystal-
line solids in high yield. Complex 13 and its bromide analogue
have been reported previously.9 Complexes 11 and 12 were
characterized by elemental analysis, mass spectrometry and
multinuclear NMR spectroscopies (Table 1). Complex 13 was
found to be insufficiently soluble for an NMR study. The trans
geometry was established by comparison of the values of
1J(PtP) with those for a range of cis and trans bis(phosphine)-
dichloroplatinum complexes.33 The values are intermediate
between those of non-fluorinated trialkyl- and triaryl-phos-
phines, 2300–2600 Hz,33 and that of 3140 Hz for trans-
[PtCl2{P(C6F5)3}2].13 The trans geometry of 12 was further
confirmed by single-crystal X-ray diffraction (Fig. 11). Selected
bond distances and angles are given in Table 6. The structure
possesses no significant intermolecular interactions. The
platinum atom of 12 lies on a crystallographic centre of sym-
metry. The PPh(C6H3F2-2,6)2 ligands of 12 also show disorder
between the phenyl ring and one difluorophenyl ring which was
modelled by 20% occupancy of the fluorine atom sites F(12)
and F(16) and 90% occupancy of sites F(22), F(26), F(32) and
F(36). The P–Pt–Cl angles are 85.60(8) and 94.40(8)Њ, which are
the same within experimental error as those of the tris(penta-
fluorophenyl)phosphine analogue trans-[PtCl2{P(C6F5)3}2].13
The Pt–Cl distance is the same as that for trans-[PtCl2-
{P(C6F5)3}2].13 The Pt–P distance is ca. 0.03 Å shorter than the
Pt–PPh(C6H3F2-2,6)2 distance of 3, but ca. 0.02 Å longer than
that of trans-[PtCl2{P(C6F5)3}2] and the same as that of trans-
[PtI2{P(C6F5)3}2].12 The PPh(C6H3F2-2,6)2 ligands of 12 adopt a
conformation similar to that in complex 3, with a conformation
about the Pt–P axis as depicted in Fig. 4(c). The Pt–P–C angles
are similar to those found in 3, 6 and 9. As a result of the large
e.s.d.s of the PC–C–F angles of 12, no meaningful comparison
can be made with those of II, 3, 6 and 9.
Fig. 11 Structure of trans-[PtCl2{PPh(C6H3F2-2,6)2}2], 12. Details as
for Fig. 6.
in the phosphine ligand. The cone angle of III was calculated to
be 176 and 171Њ from the structures of 4 and 10 respectively.
Tolman10 has reported the cone angle of P(C6F5)3 as 184Њ, but
the value calculated from the structure of trans-[IrBr(CO)-
{P(C6F5)3}2]3 is only 172Њ. Thus, it appears that there is very
little difference in steric properties between difluorophenyl-
phosphines and the pentafluorophenyl analogues.
Wilson and co-workers34 have attempted to quantify the
᎐
relationship between ν(C᎐O) and the steric and electronic prop-
᎐
erties of phosphines for complexes of the form trans-[IrCl-
(CO)(PR3)2] and have developed the empirical equation (1),
᎐
ν(C᎐O) = aχ Ϫ bθ ϩ c
(1)
᎐
where a, b and c are constants, χ is the electron donor capacity
and is larger for weaker donors and θ is the cone angle.10 There-
᎐
fore, ν(C᎐O) increases with decreasing basicity and decreasing
᎐
cone angle. Presumably a similar relationship also exists for
The cone angles10 of phosphines I–III were estimated from
the structures of their complexes. That of I was calculated to be
157Њ from the structure of 2. This is comparable to the value of
158Њ for PPh2(C6F5) quoted by Tolman.10 However, the struc-
ture of trans-[PtCl2(PEt3){PPh2(C6F5)}]4 yields a value of 165Њ,
and it can be concluded that I is slightly less sterically demand-
ing than PPh2(C6F5). The cone angle of II was calculated to be
166Њ from the structure of 6 and 167Њ from that of 12. These
angles are slightly smaller than that of 171Њ for PPh(C6F5)2
reported by Tolman,10 but there are no structures of complexes
of PPh(C6F5)2 to confirm this value and with which to compare
the structures of 6 and 12. Cone angles were not obtained from
the structures of 3 and 9 because of the high degree of disorder
trans-[RhCl(CO)(PR ) ] complexes. The values of ν(C᎐O) for
᎐
᎐
3
2
trans-[MCl(CO)(PR3)2] (M = Rh or Ir) comprising I, II and III
are similar to those of trans-[MCl(CO)(PPh3)2], whereas
᎐
ν(C᎐O) for the complexes comprising pentafluorophenylphos-
᎐
phines are at significantly higher frequency and follow the order
PPh3 < PPh2(C6F5) < PPh(C6F5)2 < P(C6F5)3 for trans-[RhCl-
(CO)(PR3)2] (Table 4). For the pentafluorophenylphosphine lig-
ands the decreasing basicity dominates over the increasing cone
᎐
angle such that ν(C᎐O) increases in the order PPh (χ = 13.25
᎐
3
cmϪ1, θ = 145Њ) < PPh2(C6F5) (χ = 18.7 cmϪ1) < PPh(C6F5)2 <
P(C6F5)3 (χ = 35.6 cmϪ1).10,34 However, for difluorophenyl-
phosphines it appears that the donor and steric properties are
matched such that increases of χ and θ in the series PPh3, I, II,
168
J. Chem. Soc., Dalton Trans., 2000, 161–172

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Table 7 Infrared carbonyl stretching frequencies for [Mo(CO)4(R2PCH2CH2PR2)]
Ϫ1
᎐
ν(C᎐O)/cm
᎐
1
2
Compound
A1
A1
B1
B2
[Mo(CO)4{(C2F5)2PCH2CH2P(C2F5)2}]a
[Mo(CO)4(dfppe)]a
2064
2041
2033
2030
2020
2012
1993
1965
1965
1945
1919
1909
1982
1935
1941
1924
1907
1891
1955
1935
1916
1885
1881
1873
[Mo(CO)4{(MeO)2PCH2CH2P(OMe)2}]b
14c
[Mo(CO)4(dppe)]d
[Mo(CO)4(Et2PCH2CH2PEt2)]d
a Ref. 19. b Ref 35. c Recorded as a Nujol mull. Assignments made by comparison with the spectrum of [Mo(CO)4(dfppe)]. d Ref. 36.
᎐
III leave ν(C᎐O) constant. Since the values of θ for phosphines
elemental analysis and FAB mass spectrometry, which showed
᎐
I–III are similar or slightly less than those for the pentafluoro-
phenyl analogues it follows that, as expected, I–III are more
basic than the respective pentafluorophenylphosphines.
peaks at m/z 807, 772 and 737 consistent with Mϩ, [M Ϫ Cl]ϩ
and [M Ϫ Cl]2ϩ, but was insufficiently soluble in all common
solvents for an NMR spectroscopic investigation. On the basis
of the very different solubilities of 15 and [PtCl2(dfppe)], and
the tendency of diphosphine IV to bridge [IrCl2(η5-C5Me5)]
moieties rather than chelate,24 we tentatively suggest that com-
pound 15 is a polymeric species, as depicted in Scheme 2, rather
than a mononuclear species. Although the mass spectral data
suggest a mononuclear compound, this may arise from frag-
mentation of the polymer under the conditions required to
observe a spectrum.
Transition metal complexes of diphosphine IV
Treatment of cis-[Mo(CO)4(NHC5H10)2] with IV in dichloro-
methane afforded [Mo(CO)4{(C6H3F2-2,6)2PCH2CH2P(C6H3-
F2-2,6)2}] 14 as pale yellow crystals (Scheme 2). The 31P-{1H}
Conclusion
In conclusion, we have prepared the new 2,6-difluoro-
phenylphosphines PPhx(C6H3F2-2,6)3 Ϫ x (x = 1 or 2) and a range
of transition metal complexes of these and the previously
reported phosphines P(C6H3F2-2,6)3 and (C6H3F2-2,6)2PCH2-
CH2P(C6H3F2-2,6)2. The structural and spectroscopic data of
the complexes indicate that, as expected, these phosphines are
more basic than the analogous pentafluorophenylphosphines,
but much less basic than triphenylphosphine or dppe. The di-
fluorophenylphosphines exert a similar or slightly smaller steric
effect than the analogous pentafluorophenylphosphines, and
possess more acute PC–C–F angles than the latter.
Experimental
Physical measurements
Proton, 19F and 31P NMR spectra were recorded on Bruker
DRX400, AM300 or ARX250 spectrometers: 1H (250.13,
300.14 or 400.13 MHz) were referenced internally using the
residual protio solvent resonance relative to SiMe4 (δ 0), 13C
(62.90 MHz) internally using the deuteriated solvent resonance
relative to SiMe4 (δ 0), 19F (235.36, 282.41 or 376.50 MHz)
externally to CFCl3 (δ 0) and 31P (101.26, 121.50 or 161.98
MHz) externally to 85% H3PO4 (δ 0) using the high frequency
positive convention. All chemical shifts (δ) are quoted in ppm
and coupling constants in Hz. The IR spectra were recorded
on a Digilab FTS40 Fourier transform spectrometer, EI
and positive-ion FAB mass spectra on a Kratos Concept 1H
mass spectrometer. Elemental analyses were performed by
Butterworths Ltd. or by A.S.E.P., The School of Chemistry,
The Queen’s University of Belfast.
Scheme 2 (i) cis-[Mo(CO)4(NHC5H10)2], CH2Cl2, heat; (ii) cis-[PtCl2-
(NCMe)2], CH2Cl2, heat.
and 19F-{1H} NMR spectra, which have been simulated, are the
A and X parts respectively of an AAЈX4XЈ4 spectrum and
resemble those of IV.24 The spectra have been simulated with
the values of |3J(PPЈ)| 11.0, |3J(PF)| 9.8, |5J(PFЈ)| 2.0 and
|8J(FFЈ)| 0 Hz. The values of |3J(PPЈ)| and |3J(PF)| are signifi-
cantly smaller than those of 47.4 and 30.1 Hz respectively for
IV. As expected the infrared spectrum of 14 exhibits four
carbonyl stretching bands (Table 7), which were assigned by
Materials
comparison with the spectrum of [Mo(CO)4(dfppe)].22 The
᎐
values of ν(C᎐O), in particular the A band, give an indication
The compounds C6H3BrF2-2,6 (Fluorochem), PPh2Cl, PPhCl2,
[{RhCl(µ-Cl)(η5-C5Me5)}2], [{Rh(µ-Cl)(CO)2}2] and IrCl3ؒ
xH2O (Aldrich) were used as supplied, [{PtCl(µ-Cl)(PEt3)}2],37
[{Ir(µ-Cl)(η2,η2Ј-C8H12)}2],38 IV,24 cis-[PtCl2(NCMe)2]39 and
[Mo(CO)4(NHC5H10)2]40 were prepared as described and PCl3
was distilled under nitrogen. Diethyl ether was dried by distil-
lation under nitrogen from over sodium. Light petroleum (bp
40–60 ЊC) was used throughout.
᎐
1
of the π-acceptor properties of the ligand,22 and as can be seen
from Table 7 the π acidity of 14 is intermediate between those
of dfppe and dppe, and similar to that of the diphosphonite
complex [Mo(CO)4{(MeO)2PCH2CH2P(OMe)2}].35
Treatment of cis-[PtCl2(NCMe)2] with IV gave a white
solid of formulation [PtCl2{(C6H3F2-2,6)2PCH2CH2P(C6H3F2-
2,6)2}], 15, in high yield. Compound 15 was characterized by
J. Chem. Soc., Dalton Trans., 2000, 161–172
169

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Preparations
(2,6-Difluorophenyl)diphenylphosphine I. n-Butyllithium 1.6
M in hexane (32.5 cm3, 0,052 mol) was diluted with 30 cm3 of
diethyl ether and added during 45 min to C6H3BrF2-2,6 (10.24
g, 0.052 mol) in diethyl ether (100 cm3) at Ϫ78 ЊC under nitro-
gen and stirred for 1¹ h. The compound PPh2Cl (9.8 cm3, 0.052
¯
²
mol) in diethyl ether (50 cm3) was added to the solution during
45 min. The reaction mixture was allowed to warm slowly to
room temperature over 12 h. The resulting slurry was added to
10% NH4Cl(aq) (200 cm3) and the organic layer separated,
washed with 10% NH4Cl(aq) (100 cm3) and water (2 × 100 cm3)
and dried over MgSO4. The solution was filtered and the sol-
vent removed by rotary evaporation to yield I as a white solid,
which was purified by column chromatography using diethyl
ether as eluent. Yield 10.68 g, 70%.
Bis(2,6-difluorophenyl)phenylphosphine II. Phosphine II was
prepared similarly to I from C6H3BrF2-2,6 (8.27 g, 0.042 mol)
and PPhCl2 (3.76 g, 0.021 mol). Yield 3.46 g, 49%.
Tris(2,6-difluorophenyl)phosphine III. Phosphine III was pre-
pared similarly to I from C6H3BrF2-2,6 (10.24 g, 0.052 mol) and
PCl3 (1.2 cm3, 0.014 mol). Yield 4.51 g, 87%.
[RhCl2{PPh2(C6H3F2-2,6)}(ꢀ5-C5Me5)] 1. A slurry of [{RhCl-
(µ-Cl)(η5-C5Me5)}2] (0.010 g, 0.16 mmol) and compound I
(0.10g, 0.32 mmol) in benzene (50 cm3) was refluxed for 4¹ h.
¯
²
Removal of the solvent by rotary evaporation afforded complex
1 as an orange solid, which was recrystallized from dichloro-
methane. Yield 0.14 g, 71%.
trans-[PtCl2(PEt3){PPh2(C6H3F2-2,6)}] 2. A slurry of [{PtCl-
(µ-Cl)(PEt3)}2] (0.010 g, 0.13 mmol) and compound I (0.075 g,
0.25 mmol) in acetone (30 cm3) was heated gently for ca. 5 min.
The solution was filtered and light petroleum added to afford
pale yellow crystals of 2. Yield 0.15 g, 38%.
trans-[PtCl2(PEt3){PPh(C6H3F2-2,6)2}] 3. Complex 3 was
prepared similarly to 2 from [{PtCl(µ-Cl)(PEt3)}2] (0.153 g, 0.20
mmol) and compound II (0.134 g, 0.40 mmol). Yield 0.251 g,
87%.
trans-[PtCl2(PEt3){P(C6H3F2-2,6)3}] 4. Complex 4 was pre-
pared similarly to 2 from [{PtCl(µ-Cl)(PEt3)}2] (0.097 g, 0.14
mmol) and compound III (0.102 g, 0.28 mmol). Yield 0.116 g,
58%.
trans-[RhCl(CO){PPh2(C6H3F2-2,6)}2] 5. The dimer [{Rh(µ-
Cl)(CO)2}2] (0.027 g, 0.07 mmol) in dichloromethane (20 cm3)
was added to compound I (0.091 g, 0.31 mmol) in dichloro-
methane (30 cm3) and the mixture stirred for 30 min. Concen-
tration by rotary evaporation and addition of light petroleum
gave lemon yellow crystals of 5. Yield ca. 0.09 g, 85%.
trans-[RhCl(CO){PPh(C6H3F2-2,6)2}2] 6. Complex 6 was
prepared similarly to 5 from [{Rh(µ-Cl)(CO)2}2] (0.122 g, 0.31
mmol) and compound II (0.418 g, 1.25 mmol). Yield 0.42 g,
81%.
trans-[RhCl(CO){P(C6H3F2-2,6)3}2] 7. Complex 7 was pre-
pared similarly to 5 from [{Rh(µ-Cl)(CO)2}2] (0.120 g, 0.30
mmol) and compound III (0.555 g, 1.5 mmol). Yield 0.48 g,
88%.
trans-[IrCl(CO){PPh2(C6H3F2-2,6)}2] 8. A mixture of [{Ir(µ-
Cl)(η2,η2Ј-C8H12)}2] (0.168 g, 0.25 mmol) and compound I
(0.298 g, 1.00 mmol) in dichloromethane (35 cm3) was stirred at
25 ЊC under carbon monoxide for 1 h. The solvent was removed
170
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under reduced pressure and the solid product washed with light
petroleum and dried in vacuo. Yield 0.37 g, 87%.
References
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trans-[IrCl(CO){PPh(C6H3F2-2,6)2}2] 9. Complex 9 was pre-
pared similarly to 8 from [Ir(µ-Cl)(η2,η2Ј-C8H12)] (0.182 g, 0.27
mmol) and compound II (0.361 g, 1.08 mmol). Yield 0.35 g,
70%.
trans-[IrCl(CO){P(C6H3F2-2,6)3}2] 10. A mixture of IrCl3ؒ
xH2O (0.12 g, ca. 0.35 mmol) and compound III (0.30 g, 7.04
mmol) in 2-methoxyethanol (50 cm3) was refluxed under nitro-
gen for 4 h. The solvent was removed by rotary evaporation,
and the product extracted into dichloromethane (100 cm3). The
solution was filtered and concentrated by rotary evaporation.
Addition of light petroleum precipitated 10 as a yellow solid.
Yield 0.09 g, ca. 25%.
trans-[PtCl2{PPh2(C6H3F2-2,6)}2] 11. A slurry of cis-[PtCl2-
(NCMe)2] (0.202 g, 0.58 mmol) and compound I (0.346 g, 1.16
mmol) in dichloromethane (50 cm3) was refluxed for 4 h. After
cooling to room temperature the solvent was removed by rotary
evaporation to yield the product as a pale yellow solid, which
was washed with light petroleum. Yield 0.48 g, 96%.
10 C. A. Tolman, Chem. Rev., 1977, 77, 313.
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17 A. Karipides and C. M. Cosio, Acta Crystallogr., Sect. C, 1989, 45,
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trans-[PtCl2{PPh(C6H3F2-2,6)2}2] 12. Complex was prepared
similarly to 11 from cis-[PtCl2(NCMe)2] (0.349 g, 1.00 mmol)
and compound II (0.674 g, 2.02 mmol). Yield 0.706 g, 76%.
[Mo(CO)4{(C6H3F2-2,6)2PCH2CH2P(C6H3F2-2,6)2}] 14.
A
mixture of [Mo(CO)4(NHC5H10)2] (0.1 g, 0.294 mmol) and com-
pound IV (0.14 g, 0.258 mmol) in dichloromethane (30 cm3)
was refluxed for 4 h. The solution was concentrated by rotary
evaporation to afford pale yellow crystals of 14, which were
washed with methanol and dried in vacuo. Yield 0.11 g, 58%.
18 S. Park, M. Pointer-Johnson and D. M. Roundhill, J. Am. Chem.
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[{PtCl2[(C6H3F2-2,6)2PCH2CH2P(C6H3F2-2,6)2]}n] 15. Phos-
phine IV (0.13 g, 0.24 mmol) was added to cis-[PtCl2(NCMe)2]
(0.09 g, 0.247 mmol) in dichloromethane and stirred for 1¹ h
to give a white precipitate. The solid was filtered off, washed
with dichloromethane, acetone and light petroleum and dried
in vacuo. Yield 0.16 g, 84%.
¯
²
X-Ray crystallography
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Crystals of compound I were grown from acetone–light petrol-
eum and II and III from diethyl ether, complexes 2, 3 and 4
from acetone, 6 from chloroform and 9, 10 and 12 from
dichloromethane. Data were collected at 293(2) K (I, 4 and 12),
180(2) K (II), 190(2) K (III, 3, 6, 9 and 10) and 200(2) K (2).
Table 8 summarizes the crystallographic data. All data sets
were corrected for Lorentz-polarization effects. For the metal
complex structures empirical absorption corrections were
applied to the data sets based on psi scan data. The structures
of I, II and III were solved by direct methods using the program
SHELXTL PC41 and refined on F2 with full-matrix least
squares using the program SHELXL 97.42 The remaining struc-
tures were solved by Patterson methods using the program
SHELXTL PC.41 All non-hydrogen atoms were refined with
anisotropic displacement parameters. The hydrogen atoms were
included in calculated positions (C–H 0.96 Å) with isotropic
displacement parameters set at 1.2Ueq of the bonded carbon
atom or 1.5Ueq for methyl H atoms.
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18.
CCDC reference number 186/1733.
See http://www.rsc.org/suppdata/dt/a9/a907759f/ for crystal-
lographic files in .cif format.
Acknowledgements
We thank Dr G. Eaton for recording the mass spectra, Dr G. A.
Griffith for assistance in recording the NMR spectra and the
EPSRC (A. M. S.) and the Royal Society (E. G. H.) for support.
J. Chem. Soc., Dalton Trans., 2000, 161–172
171

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39 F. R. Hartley, S. G. Murray and C. A. McAuliffe, Inorg. Chem.,
1979, 18, 1394.
42 G. M. Sheldrick, SHELXL 97, Program for Crystal Structure
Refinement, University of Göttingen, 1997.
40 D. J. Darensbourg and R. L. Kump, Inorg. Chem., 1978, 17, 2680.
41 G. M. Sheldrick, SHELXTL PC, Release 4.2, Siemens Analytical
X-Ray Instruments, Madison, WI, 1991.
Paper a907759f
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J. Chem. Soc., Dalton Trans., 2000, 161–172