Tetramethyl(perfluoroalkyl)cyclopentadienyl rhodium(III) complexes containing phosphorus and nitrogen monodentate donors. Crystal structure of [(η5 - C5 Me4 C4 F9) Rh (PPr3i) Cl2]

Article abstract of DOI:10.1016/j.jorganchem.2006.12.004

Cleavage of a double μ-halo bridge in complexes [(C₅Me₄C_nF_2n+1)RhX₂]₂ (n = 4, 6; X = Cl, Br) with two-electron monodentate P-donors like phosphines or phosphites or monodenate N-donors like pyridine-derived heterocyclic amines gave mononuclear Rh(III) complexes of piano-stool type [(C₅Me₄C_nF_2n+1)RhX₂L] (L = two-electron donor). Crystal structure of [(η⁵ - C₅ Me₄ C₄ F₉) Rh (PPr₃ⁱ) Cl₂] was determined by X-ray diffraction. The compound had a pseudo-tetrahedral ligand arrangement around the Rh atom. The perfluoroalkyl chain was averted from the phosphine ligand but not completely; after projection to the ring plane the P- (ring centroid) -CF₂ angle was around 166°. In contrast to their Cp^* analogs, the pyridine complexes were stable in solution at room temperature. Free rotation of triarylphosphine ligands around Rh-P bond and 2-substituted pyridine ligands around Rh-N bond was hindered, giving the values of ΔG^? = 14.8 ± 0.1 kcal mol^-1 at 27 °C and ΔG^? = 14.9 ± 0.1 kcal mol^-1 at 52 °C for tri(m-tolyl)phosphine and quinoline complexes, respectively, as followed from the analysis of variable temperature NMR spectra. In the 2-methylpyridine complex, the hindered rotation was accompanied by a reversible decoordination of the ligand at higher temperatures.

Full text of DOI:10.1016/j.jorganchem.2006.12.004

Journal of Organometallic Chemistry 692 (2007) 1557–1570
www.elsevier.com/locate/jorganchem
Tetramethyl(perfluoroalkyl)cyclopentadienyl rhodium(III)
complexes containing phosphorus and nitrogen monodentate
donors. Crystal structure of ½ðg5-C5Me4C4F9ÞRhðPPr3i ÞCl2ꢀ
a,b,
a
a
b
ˇ
*
ˇ
´
´
Jan Cermak
, Jaroslav Zadny , Alena Krupkova , Katerina Lopatova ,
´ ˇ
´ ´
b
b
b
a
c
ˇ
´
´
´
´
Alena Vlachova , Thu Huong Nguyen Thi , Jana Sauliova , Jan Sy´kora , Ivana Cısarˇova
a
Institute of Chemical Process Fundamentals AS CR, Rozvojova´ 135, 165 02 Prague 6, Czech Republic
ˇ
Department of Chemistry, Faculty of Science, Purkynje University Ustı´ nad Labem, Ceske´ mla´dezˇe 8, 400 96, Ustı´ nad Labem, Czech Republic
b
´
´
c
Center of Molecular and Crystal Structures, Faculty of Natural Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic
Received 20 July 2006; received in revised form 30 November 2006; accepted 5 December 2006
Available online 9 December 2006
Abstract
Cleavage of a double l-halo bridge in complexes [(C5Me4CnF2n+1)RhX2]2 (n = 4, 6; X = Cl, Br) with two-electron monodentate P-
donors like phosphines or phosphites or monodenate N-donors like pyridine-derived heterocyclic amines gave mononuclear Rh(III)
complexes of piano-stool type [(C5Me4CnF2n+1)RhX2L] (L = two-electron donor). Crystal structure of ½ðg5-C5Me4C4F9ÞRhðPPr3i ÞCl2ꢀ
was determined by X-ray diffraction. The compound had a pseudo-tetrahedral ligand arrangement around the Rh atom. The perflu-
oroalkyl chain was averted from the phosphine ligand but not completely; after projection to the ring plane the P– (ring centroid) –
CF2 angle was around 166ꢀ. In contrast to their Cp* analogs, the pyridine complexes were stable in solution at room temperature. Free
rotation of triarylphosphine ligands around Rh–P bond and 2-substituted pyridine ligands around Rh–N bond was hindered, giving the
values of DGà = 14.8 0.1 kcal molꢁ1 at 27 ꢀC and DGà = 14.9 0.1 kcal molꢁ1 at 52 ꢀC for tri(m-tolyl)phosphine and quinoline com-
plexes, respectively, as followed from the analysis of variable temperature NMR spectra. In the 2-methylpyridine complex, the hindered
rotation was accompanied by a reversible decoordination of the ligand at higher temperatures.
ꢁ 2006 Elsevier B.V. All rights reserved.
Keywords: Fluorous cyclopentadienes; Rhodium complexes; Hindered ligand rotation
1. Introduction
pentadiene as a precursor providing the ligand with steric
properties comparable to Cp* but electronic properties
close to Cp. Several complexes with tetramethyl(trifluo-
romethyl)cyclopentadienyl ligand were reported [3] includ-
ing measurements documenting the above mentioned
properties of the ligand. Recently, as a part of our ongoing
effort to synthesize fluorophilic cyclopentadienes [4], we
developed an easy and practical synthesis of analogs of
the Gassman ligand containing longer perfluorinated
chains (‘‘ponytails’’) and prepared some of their Rh(III)
and Rh(I) complexes [5] with an additional feature – solu-
bility in fluorous media [6] and in supercritical CO2. We
now report the synthesis and properties of monodentate
P and N donor complexes with sterically demanding
[(C5Me4CnF2n+1)Rh] fragment and their comparison with
Being devised to modify both electronic (more electron
donating) and steric (more bulky) properties of g5-cyclo-
pentadienyl ligand, pentamethylcyclopentadienyl, Cp*, is
now ubiquitous in organometallic chemistry [1]. Further
developments led to even much bulkier or supracyclopenta-
dienyl ligands [2], the changes in size being usually accom-
panied by the changes of electronic properties compared to
unsubstituted Cp. A cyclopentadienyl ligand that would
modify steric properties only was reported by Gassman
et al. [3a] who prepared tetramethyl(trifluoromethyl)cyclo-
*
Corresponding author. Tel.: +420 2 2039 0356; fax: +420 2 2092 0661.
ˇ
´
E-mail address: cermak@icpf.cas.cz (J. Cermak).
0022-328X/$ - see front matter ꢁ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.12.004

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J. Cerma´k et al. / Journal of Organometallic Chemistry 692 (2007) 1557–1570
1558
known [Cp*Rh] analogs to find out the influence of higher
p-acidity of the perfluoroalkylated ligand on the properties
of the complexes.
799 (s), 817 (s), 854 (m), 1008 (m), 1134 (s), 1173 (vs),
1191 (vs), 1210 (vs), 1229 (vs), 1260 (m), 1347 (s), 1395
(s), 1477 (s), 2911 (w), 2962 (w).
1H NMR (299.98 MHz, CDCl3): d 1.86 (s, CH3); 2.05 (s,
CH3).
2. Experimental
13C NMR (75.44 MHz, CDCl3): d 9.94 (s, CH3); 11.37
(bs, CH3); 73.41 (m, F2C–C–Rh); 98.66 (m, C–Rh);
102.49 (m, C–Rh); 102–121 (m, C4F9).
2.1. General
Syntheses of rhodium complexes were carried out under
argon or dry nitrogen atmosphere. Most of the compounds
described in this paper, however, are stable to air at least in
the solid state.
19F NMR (282.24 MHz, CDCl3): d ꢁ126.24 (m, CF2);
ꢁ122.41 (m, CF2); ꢁ105.92 (m, CF2); ꢁ81.29 (m, CF3).
2.2.2. Dichloro-(perfluorobutyl)tetramethylcyclo-
pentadienyltrimethylphosphine-rhodium(III) (3)
Starting phosphines and heterocyclic amines were
commercial products (Aldrich) used without further puri-
fication, except tri(m-tolyl)phosphine, triethylphosphite,
tris(2-biphenylyl)phosphite, 2-bromopyridine, 2-methyl-
pyridine, 4-methylpyridine and 4-methylaniline (p-tolui-
dine) which were from laboratory stock; their purity
was checked by NMR. Acetone was dried over CaCl2.
Di-l-chloro-dichloro-bis[g5-(perfluoroalkyl)tetramethylcy-
clopentadienyl]-dirhodium(III) complexes were prepared
according to a literature method [5]. 1H, 31P{1H},
19F{1H}, and 13C{1H} Infrared spectra were recorded
on a Nicolet Impact 400 instrument in the range of
4000–400 cmꢁ1. Samples were measured in thin films by
reflexion technique and by transmission technique after
evaporation from dichloromethane solutions. NMR spec-
tra were measured on a Varian Mercury 300 spectrome-
ter at 299.98, 80.98, 282.23, and 75.44 MHz, respectively,
in CDCl3 solution unless stated otherwise. Chemical
shifts (d) are reported in ppm relative to TMS, refer-
enced to hexamethyldisilane or the solvent peak (1H,
13C), external H3PO4 (31P), and external CFCl3 (19F).
Methanol and ethylene glycol were used for temperature
calibration in variable temperature experiments. The
Gibbs activation energy of rotation was determined by
the method of peak separation at coalescence tempera-
ture. The values for peak separation at coalescence tem-
perature were extrapolated from slow exchange region
using linear regression.
A solution of trimethylphosphine in THF (396 ll of
1.0 M soln., 0.396 mmol) was added to a solution of 1
(203 mg, 0.198 mmol) in THF (50 ml). The reaction mix-
ture was magnetically stirred for 1.5 h, then the solvent
was evaporated leaving red viscous material as a product
(200 mg, 86%). Complex 17 was prepared in the same way.
Elem. Anal. Calc. for C16H21Cl2F9PRh: C, 32.62; H,
3.59. Found: C, 32.08; H, 4.26%. IR (cmꢁ1): 678 (w), 733
(s), 799 (vs), 822 (vs), 859 (s), 955 (vs), 1022 (s), 1093 (s),
1134 (vs), 1199 (vs), 1216 (vs), 1233 (vs), 1259 (vs), 1284
(m), 1348 (m), 1408 (m), 2912 (m), 2960 (m).
2
1H NMR (299.98 MHz, CDCl3): d 1.72 (d, JPH
=
4
11.7 Hz, CH3); 1.78 (d, JPH = 3.1 Hz, CH3); 1.91 (d,
4JPH = 4.0 Hz, CH3).
13C NMR (75.44 MHz, CDCl3): d 9.02 (d, JPC
=
3
1
1.7 Hz, CH3); 10.26 (bs, CH3); 15.78 (d, JPC = 35.0 Hz);
77.87 (m, F2C–C–Rh); 103.47 (bs, C–Rh); 104.22 (m, C–
Rh); 108–120 (m, C4F9).
31P NMR (121.44 MHz, CDCl3):
d
14.11 (d,
1JPRh = 129.8 Hz).
2.2.3. Dichloro-(perfluorobutyl)tetramethylcyclo-
pentadienyl-triethylphosphine-rhodium(III) (4)
Triethylphosphine (58 ll, 46 mg, 0.39 mmol) was added
to a solution of 1 (200 mg, 0.195 mmol) in chloroform
(15–20 ml). The reaction mixture was magnetically stirred
for 2–4 h, then the solvent was evaporated leaving red
viscous material as a product (200 mg, 81%). Tributyl-
phosphine, triisopropylphosphine, tricyclohexylphosphine,
triphenylphosphine, tri(m-tolyl)phosphine, triethylphos-
phite, tris(2-biphenylyl)phosphite, diphenyl-p-tolylphos-
phine, and tri(p-tolyl)phosphine (from both Cl and Br
dimer) complexes 5–14 were prepared in an analogous
2.2. Syntheses of the complexes
2.2.1. Di-l-bromo-dibromo-bis[g5-(perfluorobutyl)-
tetramethylcyclopentadienyl]-dirhodium(III), 2
Twenty equivalents of NaBr (503 mg, 4.89 mmol) were
added to a solution of dichloro dimer 1 (251 mg,
0.245 mmol) in acetone (25 ml). The reaction mixture was
refluxed with stirring for 2 h, after cooling down the sol-
vent was evaporated in vacuum. The residue was exctracted
with dichloromethane (50 ml), filtered, and hexane (7 ml)
added. Partial evaporation of solvents gave red powder,
the solvent mixture was decanted and the product
(230 mg, 78%) dried in vacuum.
way.
3
1H NMR (299.98 MHz, CDCl3): d 1.18 (dt, JHH
=
3
4
7.5 Hz, JPH = 15.8 Hz, CH3); 1.77 (d, JPH = 2.6 Hz,
CH3); 1.88 (d, JPH = 3.1 Hz, CH3); 2.18 (dq, JHH
4
3
=
2
7.5 Hz, JPH = 11.0 Hz, CH2).
13C NMR (75.44 MHz, CDCl3): d 7.98 (d, JPC
=
2
5.1 Hz, CH3); 9.12 (s, CH3); 10.33 (bs, CH3); 17.83 (d,
1JPC = 28.7 Hz, CH2); 84.03 (m, F2C–C–Rh); 103.65 (m,
Elem. Anal. Calc. for C26H24Br4F18Rh2: C, 25.94; H,
2.01. Found: C, 24.63; H, 2.01%. IR (cmꢁ1): 489 (m), 532
(m), 556 (w), 573 (m), 638 (m), 701 (w), 733 (s), 749 (m),
C–Rh); 104.77 (m, C–Rh); 109–121 (m, C4F9).
1
31P NMR (121.44 MHz, CDCl3): d 34.37 (d, JPRh
=
130.7 Hz).

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1559
2.2.4. Dichloro-(perfluorobutyl)tetramethylcyclo-
pentadienyl-tri(n-butyl)phosphine-rhodium(III) (5)
2.2.7. Dichloro-(perfluorobutyl)tetramethylcyclo-
pentadienyl-triphenylphosphine-rhodium(III) (8)
Yield 94%.
Yield 96%. Elem. Anal. Calc. for C31H27Cl2F9PRh: C,
48.02; H, 3.51. Found: C, 47.17; H, 3.29%. IR (cmꢁ1):
455 (m), 500 (vs), 513 (vs), 526 (vs), 699 (vs), 732 (vs),
823 (s), 860 (s), 1000 (m), 1095 (s), 1134 (vs), 1194 (vs),
1218 (vs), 1235 (vs), 1348 (s), 1404 (m), 1435 (vs), 1483
3
1H NMR (299.98 MHz, CDCl3): d 0.93 (t, JHH
=
7.0 Hz, CH3); 1.38 (m, CH2); 1.48–1.60 (m, CH2); 1.75
4
4
(d, JPH = 3.1 Hz, CH3); 1.86 (d, JPH = 3.1 Hz, CH3);
2.07–2.16 (m, CH2).
13C NMR (75.44 MHz, CDCl3): d 9.09 (d, JPC
=
(s), 2915 (w), 2982 (w), 3055 (m).
3
4
1.4 Hz, CH3); 10.37 (bs, CH3); 13.63 (s, CH3); 24.34
1H NMR (299.98 MHz, CDCl3): d 1.46 (d, JPH
=
2
1
(d, JPC = 13.2 Hz, CH2); 25.24 (d, JPC = 27.6 Hz,
3.5 Hz, CH3); 1.48 (bs, CH3); 7.32 (m, 9CHAr); 7.79–7.85
3
CH2); 25.75 (d, JPC = 4.3 Hz, CH2); 83.84 (m, F2C–C–
(m, 6CHAr).
3
Rh); 103.73 (m, C–Rh); 104.60 (m, C–Rh); 107–126 (m,
C4F9).
13C NMR (75.44 MHz, CDCl3): d 8.63 (d, JPC
=
1.7 Hz, CH3); 9.66 (bs, CH3); 78.8 (m, F2C–C–Rh),
102.24 (m, C–Rh); 107.00 (m, C–Rh); 115–119 (m, C4F9),
127.86 (bs, C-arom.); 130.65 (bs, C-arom.); 134.87 (bs, C-
arom.).
19F NMR (282.24 MHz, CDCl3): d ꢁ126.26 (m, CF2);
ꢁ122.02 (m, CF2); ꢁ106.35 (m, CF2); ꢁ81.36 (m, CF3).
31P NMR (121.44 MHz, CDCl3): d 28.37 (d, JPRh
=
1
130.6 Hz).
19F NMR (282.24 MHz, CDCl3): d ꢁ126.24 (m, CF2);
ꢁ122.04 (m, CF2); ꢁ106.63 (bs, CF2); ꢁ81.35 (m,
2.2.5. Dichloro-(perfluorobutyl)tetramethylcyclo-
pentadienyl-triisopropylphosphine-rhodium(III) (6)
Yield 85%.
CF3).
1
31P NMR (121.44 MHz, CDCl3): d 31.3 (d, JPRh
=
137.3 Hz).
1H NMR (299.98 MHz, CDCl3): d 1.41 (dd, JHH
=
3
3
4
7.5 Hz, JPH = 14.1 Hz, CH3); 1.70 (d, JPH = 2.6 Hz,
2.2.8. Dichloro-(perfluorobutyl)tetramethylcyclo-
pentadienyl-tri(m-tolyl)phosphine-rhodium(III) (9)
CH3); 1.83 (bs, CH3); 2.78–2.94 (m, CH).
13C NMR (75.44 MHz, CDCl3): d 9.28 (d, JPC
=
3
Yield 95%. Elem. Anal. Calc. for C34H33Cl2F9PRh: C,
49.96; H, 4.07. Found: C, 48.48; H, 3.80%. IR (cmꢁ1):
452 (m), 464 (m), 479 (m), 556 (s), 695 (s), 732 (s), 781
(m), 822 (s), 860 (m), 998 (m), 1108 (s), 1134 (vs), 1197
(vs), 1217 (vs), 1234 (vs), 1346 (s), 1403 (s), 1449 (m),
1478 (m), 1592 (m), 2856 (w), 2920 (m), 2974 (w), 3013–
3053 (w, mp).
2
1.4 Hz, CH3); 11.22 (bs, CH3); 20.42 (d, JPC = 2.4 Hz);
1
27.59 (d, JPC = 27.6 Hz, CH); 82.84 (m, F2C–C–Rh);
103.70 (m, C–Rh); 105.60 (m, C–Rh); 107.5–118.0 (m,
C4F9).
19F NMR (282.24 MHz, CDCl3): d ꢁ126.26 (m, CF2);
ꢁ121.57 (m, CF2); ꢁ106.96 (m, CF2); ꢁ81.35 (m,
1H NMR (299.98 MHz, CDCl3):
d
1.46 (d,
CF3).
31P NMR (121.44 MHz, CDCl3): d 50.26 (d, JPRh
=
1
4
4JPH = 3.5 Hz, CH3); 1.48 (d, JPH = 3.7 Hz, CH3); 2.32
129.6 Hz).
(bs, CH3(m-tol)); 7.47–7.77 (m, CHAr).
13C NMR (75.44 MHz, CDCl3): d 8.57 (s, CH3); 9.58 (s,
CH3); 21.31 (s, CH3(m-tol)); 78.8–79.6 (m, F2C–C–Rh);
102.20 (m, C–Rh); 106.96 (m, C–Rh); 110–120 (m, C4F9);
127.52 (bs, C-arom.); 131.76 (bs, C-arom.); 135.79 (bs, C-
arom.); 137.47 (bs, C-arom.).
2.2.6. Dichloro-(perfluorobutyl)tetramethylcyclo-
pentadienyl-tricyclohexylphosphine-rhodium(III) (7)
Yield 98%.
1H NMR (299.98 MHz, CDCl3): d 1.68 (d, JPH
=
4
19F NMR (282.24 MHz, CDCl3): d ꢁ126.23 (m, CF2);
2.9 Hz, CH3); 1.82 (bs, CH3); 1.23–2.58 (m, C6H11);
(C6D6): d 1.39 (d, JPH = 2.6 Hz, CH3); 1.67 (bs, CH3);
4
ꢁ121.97 (m, CF2); ꢁ106.72 (m, CF2); ꢁ81.36 (m,
1.00–2.65 (m, C6H11).
CF3).
13C NMR (75.44 MHz, CDCl3): d 9.26 (d, JPC
=
3
31P NMR (121.44 MHz, CDCl3): d 31.7 (d, JPRh
=
1
1.4 Hz, CH3); 11.18 (bs, CH3); 26.08 (s, CH2); 27.42 (d,
136.4 Hz).
1
2JPC = 10.1 Hz, CH2); 30.07 (s, CH2); 38.05 (d, JPC
=
17.9 Hz, CH); ca. 77.4 (m, F2C–C–Rh, obscured by
CDCl3), 103.65 (m, C–Rh); 104.4 (m, C–Rh); 110–120
(m, C4F9); (C6D6): d 9.69 (s, CH3); 11.78 (bs, CH3);
2.2.9. Dichloro-(perfluorobutyl)tetramethylcyclo-
pentadienyl-triethylphosphite-rhodium(III) (10)
Yield 82%.
2
3
1H NMR (299.98 MHz, CDCl3): d 1.31 (t, JHH
=
26.98 (s, CH2); 28.26 (d, JPC = 10.1 Hz, CH2); 30.98 (s,
1
4
CH2); 38.80 (d, JPC = 17.9 Hz, CH); 77.52 (m, F2C–C–
7.0 Hz, CH3); 1.72 (d, JPH = 4.4 Hz, CH3); 1.89
3
3
Rh), 104.21 (m, C–Rh); 105.35 (m, C–Rh); 110–120 (m,
C4F9).
(bs, CH3); 4.30 (dq, JHH = 7.0 Hz, JPH = 7.0 Hz,
CH2).
19F NMR (282.24 MHz, CDCl3): d ꢁ126.23 (m, CF2);
13C NMR (75.44 MHz, CDCl3): d 8.76 (d, JPC
=
3
3
ꢁ121.67 (m, CF2); ꢁ106.37 (m, CF2); ꢁ81.38 (t,
2.6 Hz, CH3); 10.04 (d, JPC = 2.6 Hz, CH3); 15.97 (d,
3JFF = 9.9 Hz, CF3).
2
3JPC = 6.0 Hz, CH3); 64.46 (d, JPC = 7.5 Hz, CH2); 79.45
1
31P NMR (121.44 MHz, CDCl3): d 41.97 (d, JPRh
=
(m, F2C–C–Rh), 103.98 (m, C–Rh); 107.22 (m, C–Rh);
108–120 (m, C4F9).
1
128.9 Hz); (C6D6): d 41.14 (d, JPRh = 129.9 Hz).

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1560
3
19F NMR (282.24 MHz, CDCl3): d ꢁ126.29 (m,
13C NMR (75.44 MHz, CDCl3): d 8.55 (d, JPC
=
CF2); ꢁ122.4 (m, CF2); ꢁ106.68 (bs, CF2); ꢁ81.36 (m,
1.2 Hz, CH3); 9.70 (bs, CH3); 21.25 (bs, CH3 (p-tol));
80.11 (m, F2C–C–Rh); 101.54 (m, C–Rh); 106.88 (m, C–
Rh); 108.8–120.8 (m, C4F9); 128.51 (m, C-arom.); 134.72
(m, C-arom.); 140.77 (m, C-arom.).
CF3).
1
31P NMR (121.44 MHz, CDCl3): d 104.13 (d, JPRh
=
203.1 Hz).
19F NMR (282.24 MHz, CDCl3): d ꢁ126.25 (m, CF2);
2.2.10. Dichloro-(perfluorobutyl)tetramethylcyclo-
ꢁ122.08 (m, CF2); ꢁ106.80 (m, CF2); ꢁ81.38 (m,
pentadienyl-tris(2-biphenylyl)phosphite-rhodium(III) (11)
Yield 95%. Elem. Anal. Calc. for C49H39Cl2F9O3PRh:
C, 55.96; H, 3.74. Found: C, 54.23; H, 3.51%. IR (cmꢁ1):
697 (s), 730 (s), 753 (s), 821 (m), 861 (m), 927 (vs, br),
1053 (s), 1116 (s), 1135 (vs), 1175 (vs), 1202 (vs), 1216
(vs), 1233 (vs), 1347 (m), 1433 (vs), 1480 (vs), 1503 (s),
1581 (m), 1603 (m), 2921 (w), 2978 (w), 3027 (m), 3058
(m).
CF3).
31P NMR (121.44 MHz, CDCl3): d 30.25 (d, JPRh
=
1
135.9 Hz).
2.2.13. Dibromo-(perfluorobutyl)tetramethylcyclo-
pentadienyl-tri(p-tolyl)phosphine-rhodium(III) (14)
Yield 93%.
1H NMR (299.98 MHz, CDCl3):
d
1.55 (d,
1H NMR (299.98 MHz, CDCl3):
d
1.17 (d,
4JPH = 3.5 Hz, CH3); 1.68 (bs, CH3); 2.38 (bs, CH3 (p-
tol)); 6.70–7.45 (m, CHAr); 7.67 (m, CHAr).
4
4JPH = 5.9 Hz, CH3); 1.48 (d, JPH = 5.0 Hz, CH3); 6.9–
7.6 (m, CHAr).
13C NMR (75.44 MHz, CDCl3): d 9.30 (s, CH3); 10.56
(bs, CH3); 21.33 (bs, CH3 (p-tol)); 82.01 (m, F2C–C–Rh);
13C NMR (75.44 MHz, CDCl3): d 8.4 (d, 3JPC = 2.3 Hz,
3
CH3); d 9.93 (d, JPC = 1.4 Hz, CH3); 80.7–81.8 (m, F2C–
102.00 (m, C–Rh); 106.57 (m, C–Rh); 108.3–122.9 (m,
1
C–Rh); 103.28 (m, C–Rh); 108.86 (m, C–Rh); 110–120
(m, C4F9); 120.83 (d, JPC = 4.0 Hz, CHAr); 124.49 (s,
CHAr); 126.99 (s, CHAr); 127.96 (s, CHAr); 128.26 (s,
CHAr); 129.60 (s, CHAr); 131.28 (s, CHAr); 132.27 (d,
JPC = 6.0 Hz, CAr); 137.35 (s, CAr); 148.35 (d,
JPC = 13.0 Hz, CAr).
C4F9); 126.43–129.21 (m, C-arom.); 129.71 (d, JPC
=
1
13.3 Hz, C-arom.); 132.58 (d, JPC = 11.3 Hz, C-arom.);
133.6–136.2 (m, C-arom.); 139.5–142.0 (m, C-arom.);
144.25 (s, C-arom.).
19F NMR (282.24 MHz, CDCl3): d ꢁ126.24 (m, CF2);
ꢁ121.93 (m, CF2); ꢁ106.33 (m, CF2); ꢁ81.36 (m,
19F NMR (282.24 MHz, CDCl3): d ꢁ126.35 (m, CF2);
CF3).
1
ꢁ122.43 (m, CF2); ꢁ107.02 (m, CF2); ꢁ81.37 (m, CF3).
31P NMR (121.44 MHz, CDCl3): d 27.34 (d, JPRh
=
31P NMR (121.44 MHz, CDCl3):
d
95.6 (d,
138.5 Hz).
1JPRh = 236.5 Hz).
2.2.14. Dichloro-(perfluorobutyl)tetramethylcyclo-
pentadienyl-pyridine-rhodium(III) (15)
2.2.11. Dichloro-(perfluorobutyl)tetramethylcyclo-
pentadienyl-diphenyl(p-tolyl)phosphine-rhodium(III) (12)
Yield 96%.
Pyridine (33.5 mg, 0.42 mmol) was added to a solution
of 1 (200 mg, 0.195 mmol) in chloroform (5 ml) and the
mixture was stirred for 2 h at room temperature. Then
the solvent was evaporated and the residue was dried in
vacuum. The product was obtained as a red-orange solid
(178 mg, 77%). Complex 18 was prepared in the same
way.
1H NMR (299.98 MHz, CDCl3):
d
1.44 (d,
4JPH = 3.5 Hz, CH3); 1.49 (bs, CH3); 2.35 (bs, CH3 (p-
tol)); 7.10–7.23 (m, 2CHAr (p-tol)); 7.28–7.58 (m, 5CHAr
(Ph)); 7.64–7.74 (m, 2CHAr (p-tol)); 7.76–7.88 (m, 5CHAr
(Ph)).
13C NMR (75.44 MHz, CDCl3):
d
8.61 (d,
Elem. Anal. Calc. for C18H17Cl2F9NRh: C, 36.51; H,
2.89; N, 2.37. Found: C, 36.46; H, 2.75; N, 2.37%. IR
(cmꢁ1): 427 (w), 449 (w), 482 (w), 535 (w), 574 (w), 641
(m), 695 (s), 735 (vs), 761 (s), 822 (vs), 858 (s), 1000 (m),
1015 (m), 1070 (s), 1134 (vs), 1196 (vs), 1217 (vs), 1234
(vs), 1348 (s), 1405 (s), 1448 (vs), 1484 (s), 1602 (s), 2923
(w), 2979 (w), 2999–3104 (w, mp).
3JPC = 1.4 Hz, CH3); 9.69 (bs, CH3); 21.31 (s, CH3
(p-tol)); 80.0 (m, F2C–C–Rh); 101.99 (m, C–Rh); 106.97
(m, C–Rh); 113–121 (m, C4F9); 127.77 (m, C-arom.
(Ph)); 128.65 (m, C-arom. (p-tol)); 130.52 (m,
C-arom. (Ph)); 134.86 (m, C-arom. (Ph)); 141.13 (m,
C-arom. (p-tol)).
19F NMR (282.24 MHz, CDCl3): d ꢁ126.25 (m, CF2);
ꢁ122.06 (m, CF2); ꢁ106.96 (m, CF2); ꢁ81.36 (m, CF3).
1H NMR (299.98 MHz, CDCl3): d 1.67 (s, CH3); 1.84 (s,
CH3); 7.41 (m, CHmeta); 7.84 (m, CHpara); 9.03 (d,
3JHH = 5.3 Hz, CHortho).
31P NMR (121.44 MHz, CDCl3):
d
30.97 (d,
1JPRh = 136.8 Hz).
13C NMR (75.44 MHz, CDCl3): d 9.05 (s, CH3); 9.61
(s, CH3); 75.06 (dt, 1JCRh = 10.6 Hz, 3JCF not
1
2.2.12. Dichloro-(perfluorobutyl)tetramethylcyclo-
pentadienyl-tri(p-tolyl)phosphine-rhodium(III) (13)
Yield 96%.
resolved, F2C–C–Rh); 97.03 (d, JCRh = 7.2 Hz, C–Rh);
1
102.26 (d, JCRh = 7.5 Hz, C–Rh); 106–122 (m, C4F9);
125.29 (s, CHmeta); 138.38 (s, CHpara); 154.39 (s,
CHortho).
4
1H NMR (299.98 MHz, CDCl3): d 1.41 (d, JPH
=
3.1 Hz, CH3); 1.51 (bs, CH3); 2.34 (bs, CH3 (p-tol)); 7.15
(m, CHAr); 7.69 (m, CHAr).
19F NMR (282.24 MHz, CDCl3): d ꢁ126.3 (m, CF2);
ꢁ122.5 (m, CF2); ꢁ106.2 (m, CF2); ꢁ81.4 (m, CF3).

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J. Cerma´k et al. / Journal of Organometallic Chemistry 692 (2007) 1557–1570
1561
2.2.15. Dichloro-(perfluorobutyl)tetramethylcyclo-
pentadienyl-quinoline-rhodium(III) (16)
19F NMR (282.24 MHz, CDCl3): d ꢁ126.53 (m, CF2);
ꢁ123.14 (m, CF2); ꢁ122.17 (m, CF2); ꢁ121.15 (m, CF2);
Quinoline (49.4 mg, 0.38 mmol) was added to a solution
of 1 (200 mg, 0.195 mmol) in chloroform (5 ml) and the
mixture was stirred for 2 h at room temperature. The sol-
vent was then evaporated and the residue was dried in vac-
uum. The product was obtained as a red-brown solid
(250 mg, 100%).
ꢁ105.38 (m, CF2); ꢁ81.21 (m, CF3).
1
31P NMR (121.44 MHz, CDCl3): d 14.11 (d, JPRh
=
130.5 Hz).
2.2.17. Dichloro-(perfluorohexyl)tetramethylcyclo-
pentadienyl-pyridine-rhodium(III) (18)
Yield 90%.
At ꢁ20 ꢀC signals of two equally populated conform-
ers are visible in NMR spectra. Signals in 1H spectra
were assigned on the basis of gCOSY experiment at
ꢁ20 ꢀC.
1H NMR (299.98 MHz, CDCl3): d 1.67 (s, CH3); 1.85 (s,
3
CH3); 7.41 (m, CHmeta); 7.84 (m, CHpara); 9.04 (d, JHH
=
5.3 Hz, CHortho).
1H NMR (299.98 MHz, CDCl2CDCl2, ꢁ20 ꢀC): d 1.04
(s, CH3); 1.80 (s, CH3); 1.89 (s, CH3); 1.99 (s, CH3); 7.40
13C NMR (75.44 MHz, CDCl3): d 9.08 (s, CH3); 9.64 (s,
CH3); 75.32 (dt, 1JCRh = 10.7 Hz, 3JCF = 23.6 Hz, F2C–C–
3
3
(dd, JHH = 8.2 Hz, JHH = 5.6 Hz, CH3 ); 7.44 (dd,
1
1
Ar
Rh); 97.09 (d, JCRh = 7.2 Hz, C–Rh); 102.26 (d, JCRh
=
3JHH = 8.5 Hz, JHH = 4.7 Hz, CH3 ); 7.59 (m, CH6 );
3
Ar
Ar
7.5 Hz, C–Rh); 125.31 (s, CHmeta); 138.39 (s, CHpara);
154.47 (s, CHortho).
7.61 (m, CHA6 r); 7.76 (m, CHA7 r); 7.85 (m, CHA5;7r ); 8.13 (d,
3JHH = 8.5 Hz, CH8 ); 8.23 (d, JHH = 8.5 Hz, CH4 );
3
19F NMR (282.24 MHz, CDCl3) d: ꢁ126.6 (m, CF2);
ꢁ123.2 (m, CF2); ꢁ122.4 (m, CF2); ꢁ121.4 (m, CF2);
ꢁ106.0 (m, CF2); ꢁ81.2 (m, CF3).
Ar
Ar
8.25 (d, JHH = 8.2 Hz, CH4 ); 8.90 (d, JHH = 4.7 Hz,
3
3
Ar
CH2Ar); 8.90 (d, 3JHH = 8.5 Hz, CHA8 r); 9.77 (d,
3JHH = 5.6 Hz, CH2 ); (80 ꢀC): d 1.50 (s, CH3); 1.81 (s,
Ar
CH3); 7.36 (dd, JHH = 8.2 Hz, JHH = 4.7 Hz, CH3 );
3
3
Ar
3
2.2.18. Dichloro-(perfluorohexyl)tetramethylcyclo-
pentadienyl-(2-methylpyridine)-rhodium(III) (19)
2-Methylpyridine (29.6 ll, 0.30 mmol) was added to a
solution of 1 (184 mg, 0.15 mmol) in chloroform (5 ml)
and the mixture was stirred for 2 h at room temperature.
Then the solvent was evaporated and the residue was dried
in vacuum. The product was obtained as a red-orange solid
(212 mg, 100%).
7.52 (m, CH6 ); 7.70 (m, CH7 ); 7.79 (d, JHH = 8.2 Hz,
Ar
Ar
CHA5 r); 8.16 (d, JHH = 8.2 Hz, CH4 ); 8.50 (bs, CH8 );
3
Ar
Ar
9.30 (bs, CH2Ar).
13C NMR (75.44 MHz, CDCl2CDCl2, ꢁ20 ꢀC): d 9.14
(s, CH3); 9.36 (s, CH3); 9.62 (bs, CH3); 10.63 (bs,
CH3); 72.84 (m, partially overlapping with solvent peak,
F2C–C–Rh); 95.18 (m, C–Rh); 98.87 (m, C–Rh); 102.05
(m, C–Rh); 106.02 (m, C–Rh); 106–119 (m, C4F9);
121.22 (s, CHAr); 126.70 (s, CHAr); 127.40 (s, CHAr);
127.96 (s, CHAr); 128.00 (s, CAr); 128.66 (s, CHAr); 129.02
(s, CHAr); 129.43 (s, CHAr); 129.72 (s, CHAr); 130.00 (s,
1H NMR (299.98 MHz, CDCl3, ꢁ30 ꢀC): d 1.53 (s,
CH3); 1.82 (s, CH3); 1.89 (s, CH3); 1.95 (s, CH3); 3.00 (s,
3
CH3Ar); 7.22 (m, CH5 ); 7.38 (d, JHH = 7.6 Hz, CH3 );
Ar
Ar
3
7.73 (m, CH4 ); 9.44 (d, JHH = 5.6 Hz, CH6 ).
CAr); 130.38 (s, CHAr); 136.61 (s, CH8 ); 139.95 (s,
Ar
Ar
Ar
19F NMR (282.24 MHz, CDCl3, ꢁ30 ꢀC): d ꢁ126.96
(m, CF2); ꢁ123.55 (m, CF2); ꢁ122.57 (m, CF2);
ꢁ121.80 (m, CF2); ꢁ106.72 (m, CF2); ꢁ81.12 (t,
3JFF = 9.9 Hz, CF3).
CH8Ar); 146.63 (s, CA9 r); 147.32 (s, CA9 r); 150.23
(s, CH2 ); 158.71 (s, CH2 ); (80 ꢀC): d 9.13 (s, CH3);
Ar
Ar
10.06 (bs, CH3); F2C–C–Rh is overlapping with sol-
vent peak; 97.04 (bs, C–Rh); 103.00 (bs, C–Rh); 106–
120 (m, C4F9); 121.10 (s, CHAr); 126.91 (s, CHAr);
128.17 (s, CHAr); 129.12 (s, CAr); 129.74 (s,
2CHAr); 137.64 (bs, CH8 ); 147.82 ðC9 Þ; 154.04 (bs,
Dynamic processes did not allow the recording of useful
13C spectrum.
Ar
Ar
CH2Ar).
2.2.19. Dichloro-(perfluorohexyl)tetramethylcyclo-
pentadienyl-(3-methylpyridine)-rhodium(III) (20)
3-Methylpyridine (29.2 ll, 0.30 mmol) was added to a
solution of 1 (184 mg, 0.15 mmol) in chloroform (5 ml)
and the mixture was stirred for 2 h at room temperature.
Then the solvent was evaporated and the residue was dried
in vacuum. The product was obtained as a red-orange solid
(212 mg, 100%).
19F NMR (282.24 MHz, CDCl3): d ꢁ126.33 (m, CF2);
ꢁ122.35 (m, CF2); ꢁ106.33 (m, CF2); ꢁ81.35 (t,
3JFF = 9.9 Hz, CF3).
2.2.16. Dichloro-(perfluorohexyl)tetramethylcyclo-
pentadienyl-trimethylphosphine-rhodium(III) (17)
1H NMR (299.98 MHz, CDCl3): d 1.66 (s, CH3); 1.84 (s,
Yield 77%.
3
3
1H NMR (299.98 MHz, CDCl3): d 1.72 (d, JPH
=
2
CH3); 2.37 (s, CH3Ar); 7.29 (dd, JHH = 7.6 Hz, JHH
=
5.6 Hz, CH5Ar); 7.63 (d, JHH = 7.6 Hz, CH4 ); 8.83 (d,
3
4
11.7 Hz, CH3); 1.78 (d, JPH = 3.1 Hz, CH3); 1.91 (d,
4JPH = 2.0 Hz, CH3).
Ar
3JHH = 5.6 Hz, CH6 ); 8.86 (s, CH2 ).
Ar
Ar
13C NMR (75.44 MHz, CDCl3): d 9.03 (s, CH3);
13C NMR (75.44 MHz, CDCl3): d 9.09 (bs, CH3); 10.31
1
1
9.59 (s, CH3); 18.35 (s, CH3Ar); 75.10 (dt, JCRh
10.1 Hz, JCF = 23.6 Hz, F2C–C–Rh); 96.94 (d, JCRh
7.2 Hz, C–Rh); 102.17 (d, JCRh = 7.5 Hz, C–Rh);
=
=
(bs, CH3); 15.91 (d, JPC = 34.9 Hz); 78.02 (m, F2C–C–
2
1
Rh); 103.26 (bs, C–Rh); 104.45 (m, C–Rh); 106–121 (m,
C4F9).
1

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J. Cerma´k et al. / Journal of Organometallic Chemistry 692 (2007) 1557–1570
1562
105–121 (m, C6H13); 124.72 (s, CH5Ar); 135.32 (s,
CAr); 138.92 (s, CH4 ); 151.59 (s, CH6 ); 154.41 (s,
2.2.22. Dichloro-(perfluorohexyl)tetramethylcyclo-
pentadienyl-(p-toluidine)-rhodium(III) (23)
Ar
Ar
CH2Ar).
A solution of p-toluidine (32 mg, 0.30 mmol) in chlo-
roform (1 ml) was added to a solution of 1 (184 mg,
0.15 mmol) in chloroform (5 ml) and the mixture was
stirred for 2 h at room temperature. Then the solvent
was evaporated and the residue was dried in vacuum.
The product was obtained as a brick red solid (216 mg,
100%).
19F NMR (282.24 MHz, CDCl3): d ꢁ126.60 (m, CF2);
ꢁ123.22 (m, CF2); ꢁ122.21 (m, CF2); ꢁ121.55 (m, CF2);
ꢁ106.16 (t, 3JFF = 11.9 Hz, CF2); ꢁ81.28 (t, 3JFF = 9.9 Hz,
CF3).
2.2.20. Dichloro-(perfluorohexyl)tetramethylcyclo-
pentadienyl-(4-methylpyridine)-rhodium(III) (21)
4-Methylpyridine (29.2 ll, 0.30 mmol) was added to a
solution of 1 (184 mg, 0.15 mmol) in chloroform (5 ml)
and the mixture was stirred for 2 h at room temperature.
Then the solvent was evaporated and the residue was dried
in vacuum. The product was obtained as an orange solid
(212 mg, 100%).
Elem. Anal. Calc. for C22H21Cl2F13NRh: C, 36.69; H,
2.94; N, 1.94. Found: C, 37.13; H, 2.89; N, 1.80%. IR
(cmꢁ1): 444 (s), 484 (s), 534 (s), 545 (s), 662 (s), 717 (s),
732 (vs), 771 (s), 817 (vs), 1009 (vs), 1116 (vs), 1142 (vs),
1192 (vs), 1234 (vs), 1362 (s), 1401 (s), 1455 (s), 1513 (vs),
1580 (s), 2871 (w), 2930 (m), 3034-3289 (m, mp).
1H NMR (299.98 MHz, CDCl3): d 1.41 (s, CH3); 1.65 (s,
CH3); 2.32 (s, CH3Ar); 5.18 (bs, NH2); 7.13 (m, CHAr);
7.28 (m, CHAr).
Elem. Anal. Calc. for C21H19Cl2F13NRh: C, 35.72; H,
2.71; N, 1.98. Found: C, 35.87; H, 2.54; N, 1.85%. IR
(cmꢁ1): 504 (m), 666 (m), 717 (s), 733 (s), 772 (m), 806
(s), 872 (w), 889 (w), 1073 (s), 1146 (vs), 1201 (vs), 1237
(vs), 1360 (s), 1383 (w), 1404 (s), 1447 (m), 1621 (s), 2927
(w), 2980 (w), 3012-3074 (w, mp).
13C NMR (75.44 MHz, CDCl3): d 9.05 (s, CH3); 9.10 (s,
1
CH3); 20.84 (s, CH3Ar); 74.03 (dt, JCRh = 10.9 Hz,
1
2JCF = 23.9 Hz, F2C–C–Rh); 96.08 (d, JCRh = 7.7 Hz,
1
C–Rh); 103.35 (d, JCRh = 7.8 Hz, C–Rh); 106–119 (m,
C6H13); 121.10 (s, CHAr); 129.86 (s, CHAr); 135.76 (s,
CAr); 138.22 (s, CAr).
1H NMR (299.98 MHz, CDCl3): d 1.67 (s, CH3); 1.85 (s,
CH3); 2.43 (s, CH3Ar); 7.21 (d, 3JHH = 6.2 Hz, CHA3;r5); 8.86
19F NMR (282.24 MHz, CDCl3): d ꢁ126.50 (m, CF2);
(d, JHH = 6.2 Hz, CH2A;r6).
3
ꢁ123.12 (m, CF2); ꢁ122.11 (m, CF2); ꢁ121.44 (m, CF2);
13C NMR (75.44 MHz, CDCl3): d 9.13 (s, CH3); 9.70
3
ꢁ105.37 (m, CF2Cp); ꢁ81.16 (t, JFF = 9.9 Hz, CF3).
1
(s, CH3); 20.97 (s, CH3Ar); 75.24 (dt, JCRh = 10.4 Hz,
X-ray data for 6: C22H33F9P1Cl2Rh1, M = 673.27 g/
mol, monoclinic system, space group P21/c, a =
1
2JCF = 23.3 Hz, F2C–C–Rh); 96.99 (d, JCRh = 7.5 Hz,
1
C–Rh); 102.13 (d, JC–Rh = 7.5 Hz, C–Rh); 105–121 (m,
˚
22.9050(2), b = 8.5100(1), c = 13.6090(3) A, b = 92.169(8),
C6H13); 126.24 (s, CH3;5); 150.48 (s, CAr); 153.84 (s,
3
Z = 4, V = 2650.8(1) A , Dc = 1.69 g cmꢁ3, l(Mo Ka) =
Ar
˚
CH2A;r6).
0.98 mmꢁ1, crystal dimensions of 0.4 · 0.3 · 0.1 mm. Data
were collected at 150 K on a Nonius KappaCCD diffrac-
tometer with graphite monochromated Mo Ka radiation.
The structure was solved by direct methods [7]. The whole
structure was refined by full matrix least-squares on F val-
ues [8]. All heavy atoms were refined anisotropically.
Hydrogen atoms were located from expected geometry
and were refined isotropically. This model converged to
final R = 0.0222 and Rw = 0.0249 using 5116 independent
reflections (hmax = 27.5ꢀ).
19F NMR (282.24 MHz, CDCl3): d ꢁ126.54 (m, CF2);
ꢁ123.18 (m, CF2); ꢁ122.17 (m, CF2); ꢁ121.55 (m, CF2);
3
ꢁ106.01 (m, CF2); ꢁ81.17 (t, JFF = 9.9 Hz, CF3).
2.2.21. Dichloro-(perfluorohexyl)tetramethylcyclo-
pentadienyl-(3-bromopyridine)-rhodium(III) (22)
3-Bromopyridine (28.9 ll, 0.30 mmol) was added to a
solution of 1 (184 mg, 0.15 mmol) in chloroform (5 ml)
and the mixture was stirred for 2 h at room temperature.
Then the solvent was evaporated and the residue was dried
in vacuum. The product was obtained as an orange solid
(231 mg, 100%).
3. Results and discussion
1H NMR (299.98 MHz, CDCl3): d 1.70 (s, CH3); 1.86 (s,
CH3); 7.33 (m, CH5Ar); 7.98 (m, CHA4 r); 9.02 (d,
3JHH = 4.4 Hz, CH6 ); 9.13 (s, CH2 ).
Cleavage of double l-halo bridge of [Cp*RhX2]2
complex is known to take place with many monodentate
two-electron donors, e.g. phosphines [9] or amines includ-
ing heterocyclic ones [9a,10]. Reaction of complexes 1 and
2 with selected phosphines, phosphites and N-donors
(Scheme 1) gave in direct analogy mononuclear piano-
stool-type complexes 3–23 which were characterized by
Ar
Ar
13C NMR (75.44 MHz, CDCl3): d 9.21 (s, CH3); 9.75 (s,
CH3); 75.83 (dt, 1JCRh = 10.1 Hz, 2JCF = 23.9 Hz, F2C–C–
1
Rh); 97.24 (d, JCRh = 7.5 Hz, C–Rh); 102.30 (d,
1JCRh = 7.5 Hz, C–Rh); 105–121 (m, C6H13); 121.07 (s,
CAr); 125.92 (s, CH5 ); 141.25 (s, CH4 ); 152.90 (s,
1
their H, 19F, 31P{1H} and 13C{1H}NMR spectra. Fluo-
Ar
CH6Ar); 155.13 (s, CHA2Ar)r.
rine-19 spectra were the simplest showing in most cases
the presence of only one fluorous ponytail of C4 or C6
length, even if different rotamers (see below) were present.
The signals of CF2 groups appeared at a given field as broad
19F NMR (282.24 MHz, CDCl3): d ꢁ126.51 (m, CF2);
ꢁ123.13 (m, CF2); ꢁ122.12 (m, CF2); ꢁ121.45 (m, CF2);
ꢁ105.98 (t, 3JFF = 11.9 Hz, CF2); ꢁ81.18 (t, 3JFF = 9.9 Hz,
CF3).
1
singlets no coupling being resolvable. H spectra showed

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J. Cerma´k et al. / Journal of Organometallic Chemistry 692 (2007) 1557–1570
1563
two inequivalent groups of methyl protons, in addition to
signals coming from the P- or N-donor ligands. The four-
bond coupling constants between phosphorus and ring
methyl protons in the case of P donor complexes are of
the same magnitude as those found in the Cp* analogs
[9a]. Although the integral intensities of the two groups
were equal, one of the peaks was considerably broader as
observed previously [5] also with the parent dimer 1. The
broadening was tentatively ascribed to higher through-
space relaxation of methyl groups next to the perfluorinated
substituent on the Cp ring. Similar broadening was
observed also in 13C{1H} spectra which showed in case of
N-donor complexes a pair of doublets of methyl-substituted
ring carbons due to 103Rh splitting and a characteristic dou-
blet of triplets of the ponytail-substituted ring carbon atom.
Signals of P-donor complexes were more complex due to the
additional splitting of ring carbon signals by 31P, appearing
thus approximately as triplets in case of methyl-substituted
carbons or multiplets in case of CF2-substituted carbon. In
31P{1H} spectra the P-donor complexes showed doublets
As expected, steric hindrance exerted by our perflu-
oroalkyl-substituted ligands manifested itself in the prepa-
ration of their complexes, too. Whereas pyridine cleaved
the dimer 1 easily, mononuclear complexes with 2-bromo-
pyridine and 2,6-dimethylpyridine could not be obtained
and unreacted dimer was isolated from reaction mixtures.
4-Methylaniline, all methylpyridines, and 3-bromopyridine
gave also N-donor complexes. At variance with the proper-
ties of their Cp* analog [9a], the pyridine complexes 15 and
18 were stable in chloroform solution at room temperature
(as were also the other N-donor complexes) even upon com-
plete removal of the solvent, probably due to a higher p-
acidity of (C5Me4CnF2n+1) compared to Cp*. Quinoline also
reacted with 1, the product 16 was found to be approxi-
mately 1:1 mixture of two rotamers at room temperature
(see variable temperature experiments below). Somewhat
surprisingly, with ligands traditionally classified as bulky
like tricyclohexylphosphine or triisopropylphosphine the
rotation around phosphorus–metal bond was unhindered.
However, triaryl ligands did show hindered rotation at
room temperature. Sharp aromatic carbon signals were
identified in the 13C NMR spectrum of triphenylphosphine
complex 8 at 80 ꢀC, they broadened on cooling giving rise to
carbon signals of individual phenyls at ꢁ30 ꢀC. Owing to
their overlap the signals could not be inequivocably
assigned, however. Tri(p-tolyl)phosphine dichloro complex
13 was therefore prepared as well as a dibromo complex 14
to enable the direct comparison of its barrier of rotation
1
with the usual values of JPRh coupling constants.
The fragment [Cp*Rh] is known to be sterically very
demanding, therefore it limits the free movement of coordi-
nated ligands in some cases [9b] and stabilizes coordinative
unsaturation. Creation of such highly coordinatively unsat-
urated moiety (14 valence electrons for RhI) was sought
[9c,11] in attempts to activate strong, most frequently C–
H, bonds.
Rf
Cl
Rf
2 L
Cl
2
Rh
Rh
Cl
1
Rh
Cl
L
Cl
Cl
Rf
Rf = C4F9: L = PMe3, 3; PEt3, 4; P(n-C4H9)3, 5; PPri3, 6;
P(C6H11)3, 7; PPh3, 8; P(3-CH3C6H4)3, 9; P(OEt)3, 10;
P(OC6H4-2-C6H5)3, 11; PPh2(4-CH3C6H4), 12;
P(4-CH3C6H4)3, 13; NC5H5, 15; NC9H7, 16
Rf = C6F13: L = PMe3, 17; NC5H5, 18; 2-CH3C5H4N, 19;
3-CH3C5H4N, 20; 4-CH3C5H4N, 21; 3-BrC5H4N, 22;
4-CH3C6H4NH2, 23
NaBr,
acetone
Rf
Br
Rf
2 L
Br
2
Rh
Rh
Br
2
Rh
L
Br
Br
Rf
Br
Rf = C4F9: L = P(4-CH3C6H4)3, 14
Scheme 1.

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J. Cerma´k et al. / Journal of Organometallic Chemistry 692 (2007) 1557–1570
1564
with a known value for Cp* analog [9b]. Variable tempera-
ture measurements of the compound 14 were carried out in
the temperature range ꢁ40 ꢀC to 31 ꢀC. In the region of p-
tolylphosphine methyl resonances (Fig. 1) the broadening
of initially sharp signals of two inequivalent groups of pro-
tons in the ratio of 2:1 with temperature was observed, lead-
ing finally to coalescence of the signals. Coalescence
temperature 27 ꢀC was determined both from the halfwidth
and symmetry of the coalesced signal. The low-temperature
limit ꢁ19.9 ꢀC was obtained as a temperature at which the
separation of the two groups of protons (at 2.24 ppm and
2.40 ppm) started to be constant. The values were then used
for the calculation of the first order rate constant of rotation
crystal structure also in solution, i.e. the limited rotation
of cyclopentadienyl ring with respect to the legs of the
piano stool, which could cause the phosphine ligand to
experience the same steric environment (two methyl
groups in proximity) as in the Cp* complex.
Steric crowding at metal center was even more obvious
in case of complexes with nitrogen heterocyclic ligands,
which is consistent with shorter Rh-donor atom bond
and with rigid structure of substituted pyridines. In case
of pyridines bearing bulky substituents at a-position(s)
the steric effects even precluded the formation of expected
complexes.
Pyridines with less bulky groups at a-position (2-methyl-
pyridine, quinoline) did react with rhodium dimer but the
NMR spectra of products were more complex than
expected. While the spectra of other synthesized complexes
showed expected number, multiplicity, and chemical shifts
of signals (the signals of nitrogen ligands shifted slightly
downfield compared to signals of free bases and the signals
of methyl groups on cyclopentadienyl ring shifted slightly
upfield compared to parent dimer), spectra of both 16
and 19 contained more peaks than expected when mea-
sured at 25 ꢀC, some of them being quite broad. Spectra
of both complexes were highly temperature dependent
which suggested that some kind of dynamic behavior on
the NMR timescale was present.
In the case of the quinoline complex 16 there are two
complete sets of well resolved narrow signals in both pro-
ton and carbon spectra at ꢁ20 ꢀC. 1H spectrum shows
two signals for each group with the expected splitting pat-
tern and in the ratio approx. 1:1 which does not change
with the temperature until the coalescence of the signals
is reached. Only one set of signals remains at 72 ꢀC in both
spectra, though some of them are still very broad (Fig. 2).
The 19F spectrum is not affected by temperature and dis-
plays only one set of signals. This behavior can be
explained by hindered rotation of quinoline ligand about
the rhodium–nitrogen bond with two equally populated
frozen conformers at low temperatures. Similar behavior
was already described, e.g. for square planar Pd(II) and
Pt(II) quinoline complexes [13,14].
at the coalescence temperature according to a simple Eq. (1)
p
k ¼ pdm= 2
ð1Þ
This method, based on peak separation, although being
far from accurate is still widely popular and used in cases
of two exchanging sites with moderate difference in site
population [12]. The obtained value of the rate constant
106 sꢁ1 was then used in the Eyring equation to calculate
DGà and errors in DGà were calculated [9b], using the
values of 10 sꢁ1 and 2 K as the errors in k and TC,
respectively. The value of DGà thus obtained,
14.8 0.1 kcal molꢁ1, is exactly the same as the value
determined for the Cp* analog [9b]. This result was
somewhat surprising, showing our ligand to be sterically
exactly equivalent to Cp* despite the presence of one per-
fluorinated chain in place of a methyl. One possible
explanation is the fixation of the mutual positions of
the chain and the two chloride ligands close to each
other in conformation(s) not far from that found in the
31 ˚C
29 ˚C
We assume that the Cp ring is oriented in such a way
that the carbon bearing the fluorous ponytail is closest to
both chloro ligands and farthest from quinoline in analogy
with the situation in the related tri(isopropyl)phosphine
complex 6 the crystal structure of which was determined
in this work, too. The two chloro ligands and two methyl
groups closer to quinoline then divide the space around
nitrogen into four quadrants (Fig. 3) which means four
possible conformers, two of them (with quinoline in seg-
ments II and IV) being a pair of enantiomers. On the basis
of the NMR spectra at variable temperatures we suppose
that two of them are present, namely the conformer with
homoaromatic quinoline ring stuck between the two Cp
methyl groups (segment I) and the opposite one with the
same quinoline ring between both chloride ligands (seg-
ment III) which corresponds with the conformer ratio
27 ˚C
-40 ˚C
-30 ˚C
25 ˚C
-20 ˚C
-10 ˚C
23 ˚C
0 ˚C
21 ˚C
10 ˚C
15 ˚C
19 ˚C
25 ˚C
17 ˚C
2.50 2.45 2.40 2.35 2.30 2.25 2.20 2.15
ppm (f1)
Fig. 1. Variable temperature 1H spectra of 14 in the region of methyl
protons of the tri(p-tolyl)phosphine ligand.

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J. Cerma´k et al. / Journal of Organometallic Chemistry 692 (2007) 1557–1570
1565
H5
H4
H6
H3
H7
H2
H8
72˚C
52˚C
33˚C
25˚C
10˚C
H5
H5'
H7
H6 ,H6 '
H 4, H4 '
H8'
H2'
H3 , H3 '
H7'
H8
H2
-10˚C
10.00
9.50
9.00
8.50
8.00
7.50
ppm (t1)
Fig. 2. Aromatic protons region of variable temperature 1H spectra of quinoline complex 16. Labels refer to the position on the quinoline system, the two
conformers at low temperature being discriminated by an apostrophe.
1:1. The second possibility is the presence of conformer in
segment I together with the other one rotating freely in seg-
ments II to IV which is more consistent with the results
obtained for the 2-methylpyridine complex 19 (see below).
Other combinations of conformers would give different
number of signals in the NMR spectra.

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J. Cerma´k et al. / Journal of Organometallic Chemistry 692 (2007) 1557–1570
1566
are visible in the spectra, while only one set of signals
belonging to coordinated ligand and one set of free base
signals are present. At ca. 0 ꢀC two pairs of methyl signals
coalesce and only four signals are visible at higher tem-
peratures. Using the same concept of four segments as
for the quinoline complex 16, this behavior corresponds
to the presence of two enantiomeric frozen conformers
in segments II and IV at low temperature and to free
rotation of ligand in segments II to IV at higher temper-
ature. The segment I remains probably unoccupied
because of slightly larger steric demands of 2-methylpyri-
dine compared to quinoline.
The crystal structure of complex 6 is shown in Fig. 6.
The compound had a pseudo-tetrahedral ligand arrange-
ment around the Rh atom. The distance between Rh and
Fig. 3. Quadrants on [Rh(C5Me4CnF2n+1)Cl2N] fragment.
˚
the centroid of the Cp ring was 1.84 A. The bulkiest substi-
tuent on the ring, the fluoroalkyl chain, was averted from
the phosphine ligand, but not completely. After projection
to the ring plane (Fig. 7) the P– (ring centroid) –CF2 angle
was around 166ꢀ. Simultaneously, the chlorine atoms also
corrupted the potentional CS symmetry of the molecule
(as was again apparent from the projection to the Cp ring
plane). This resulted in unsymmetric intramolecular CH–
Cl interaction. Cl1 was found to be in a stronger interac-
tion with methyl hydrogen atoms of both Pri and Cp
methyl groups than Cl2. On the contrary, Cl2 created
slightly stronger intermolecular interaction with Pri groups
Not all quinoline atoms are influenced to the same
extent by rotation. The signals of protons in the position
2 and 8 of quinoline ligand show the largest peak separa-
tion (more than 250 Hz, see Fig. 2) which allowed to deter-
mine the barrier to rotation at coalescence temperature as
above. Both signals coalesce at the same temperature
(52 ꢀC) and give the same value of DGà (14.9 0.1
kcal molꢁ1).
The behavior of 2-methylpyridine complex 19 is mark-
edly different although the steric demands of both ligands
are similar due to similar substitution in the a-position of
the heterocyclic ring. In both proton (Fig. 4) and fluorine
(Fig. 5) spectra two sets of signals are detectable. The
intensity ratio between the two sets depends on tempera-
ture, but to a lesser extent also on solvent and concentra-
tion. As for the ortho proton of the heterocycle, at
ꢁ30 ꢀC the ratio of deshielded to shielded signal is as
high as 11:1 in CDCl3, gradually decreasing with increas-
ing temperature and reaching 1:1 ratio at ca. 35 ꢀC.
From 44 ꢀC only one signal is visible, which shifts further
upfield with increasing temperature. Similar behavior of
two CF2 groups closest to the Cp ring can be seen in
19F spectra (Fig. 5), except that no coalescence can be
seen in the temperature region studied. Instead, after
reaching 1:1 ratio at ca. 20 ꢀC the more shielded signal
begins to increase and dominates in the high temperature
spectra.
˚
in neighboring molecules in the crystal packing (2.96 A vs.
˚
3.02 A for Cl1).
Additionally, a typical tilting of the Cp ring substituents
to the opposite side from the coordinated metal atom was
identified in this structure. The tilting was characterized by
the value of (ring centroid)–(ring carbon)–(substituent car-
bon) angle and for the five ring substituents CF2, C10, C11,
C12, C13 amounted to about 3.0ꢀ, 1.4ꢀ, 4.9ꢀ, 3.9ꢀ, 1.3ꢀ,
respectively.
In the molecular packing we could find a characteristic
pattern for the fluoroalkyl chain containing molecules.
The fluoroalkyl chains in neighboring molecules were per-
fectly interlocking. The whole structure was thus created by
separated domains that contained either fluoroalkyl chains
or phosphine ligands.
4. Conclusions
We suppose that there is an exchange between free and
coordinated base in the solution, the rate and equilibrium
of which depends on temperature and also on other con-
ditions (solvent, concentration). In low temperature
region the exchange is slow and the product of the cleav-
age prevails in the mixture, whereas at high temperatures
there is a rapid exchange and the rhodium dimer domi-
nates in solution. The process is reversible, after cooling
the sample again the same spectra are obtained at lower
temperatures.
Twenty two new rhodium(III) complexes containing
tetramethylperfluorobutylcyclopentadienyl or tetrame-
thylperfluorohexylcyclopentadienyl ligand and monoden-
tate phosphines, phosphites or aromatic heterocyclic
N-donors as other ligands were prepared. The com-
pounds were characterized by NMR and structure of
one complex was confirmed by X-ray diffraction. The
higher p-acidity of the fluorinated cyclopentadienyl
ligands compared to Cp* was manifested by the higher
stability of their aromatic N-donor complexes. Sterically
demanding [(C5Me4Cn-F2n+1)Rh] fragment, similarly to
Cp*Rh, caused hindered rotation of aromatic phosphines
Besides the ligand exchange also the hindered rotation
is evident from the proton spectra of complex 19. Below
ꢁ20 ꢀC six signals originating from Cp methyl groups

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J. Cerma´k et al. / Journal of Organometallic Chemistry 692 (2007) 1557–1570
1567
Fig. 4. High field region of variable temperature 1H spectra of 2-methylpyridine complex 19. Labels: (s) denotes the peaks of the starting dimer, ( ) and
·
(
) the peaks of the 2-methylpyridine complex which both split into two peaks at low temperature.
*
and 2-substituted pyridines around Rh–P and Rh–N
bonds, respectively. This rotation was analyzed by vari-
able temperature NMR to reveal somewhat surprisingly
the same steric hindrance as that caused by Cp*Rh frag-

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J. Cerma´k et al. / Journal of Organometallic Chemistry 692 (2007) 1557–1570
1568
C3 C4
C5
C1
C2
60˚C
40˚C
30˚C
20˚C
10˚C
-10˚C
-30˚C
-105.0
-110.0
-115.0
-120.0
-125.0
ppm (t1)
Fig. 5. Variable temperature 19F spectra of 2-methylpyridine complex 19. Only signals of the CF2 groups of the perfluorohexyl chain are shown.
ment. A possible explanation could be the tendency of
perfluoroalkyl substituted cyclopentadienyl ring to stay
in solution in conformation or conformations that do
not allow the perfluoro substituent to get close to the
monodenate donor, securing the latter the same steric
environment as in the Cp*Rh complex.

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J. Cerma´k et al. / Journal of Organometallic Chemistry 692 (2007) 1557–1570
1569
Fig. 6. X-ray structure of 6. Some interatomic distances are indicated.
[2] (a) C. Janiak, H. Schumann, Adv. Organomet. Chem. 33 (1991) 291;
(b) J. Okuda, Top. Curr. Chem. 160 (1991) 97.
[3] (a) P.G. Gassman, J.W. Mickelson, J.R. Sowa Jr., J. Am. Chem. Soc.
114 (1992) 6942;
(b) F. Marken, H.W. Marx, U. Englert, Struct. Chem. 5 (1994)
177;
(c) P.G. Gassman, J.R. Sowa Jr., M.G. Hill, K.R. Mann,
Organometallics 14 (1995) 4879;
(d) M.C. Baschky, J.R. Sowa Jr., P.G. Gassman, S.R. Kass, J.
Chem. Soc., Perkin Trans. 2 (1996) 213;
(e) L.P. Barthel-Rosa, J.R. Sowa Jr., P.G. Gassman, J. Fischer,
B.M. McCarty, S.L. Goldsmith, M.T. Gibson, J.H. Nelson,
Organometallics 16 (1997) 1595;
(f) O.V. Gusev, M.A. Ievlev, K.A. Lyssenko, P.V. Petrovskii,
N.A. Ustynyuk, P.M. Maitlis, Inorg. Chim. Acta 280 (1998)
242;
Fig. 7. Projection to the ring plane in structure of 6.
(g) O.V. Gusev, T.A. Peganova, M.A. Ievlev, A.G. Kropotova,
K.A. Lyssenko, P.V. Petrovskii, Y.F. Oprunenko, N.A. Usty-
nyuk, J. Organomet. Chem. 622 (2001) 221.
Acknowledgements
ˇ
´
´ˇ
´
´
[4] (a) T. Brˇıza, J. Kvıcala, P. Mysık, O. Paleta, J. Cermak, Synlett
(2001) 685;
The authors thank grant agencies (Grant Agency of the
Academy of Sciences, A4072203; Ministry of Education,
Youth and Sport of the Czech Republic, LC06070) for sup-
port. Dr. Radek Fajgar is gratefully acknowledged for
measurement of IR spectra.
ˇ
´
´ˇ
´
(b) T. Brˇıza, J. Kvıcala, O. Paleta, J. Cermak, Tetrahedron 58 (2002)
3841;
ˇ
´ˇ
ˇ´
´
´
(c) J. Kvıcala, T. Brıza, O. Paleta, K. Auerova, J. Cermak,
Tetrahedron 58 (2002) 3847;
ˇ
ˇ
´
´
´
´
ˇ
´
´ˇ
(d) J. Cermak, L. S’tastna, J. Sykora, I. Cısarova, J. Kvıcala,
Organometallics 23 (2004) 2850.
ˇ
´
´
´ˇ
[5] J. Cermak, K. Auerova, H.T.T. Nguyen, V. Blechta, P. Vojtısek, J.
Appendix A. Supplementary data
´ˇ
Kvıcala, Collect. Czech. Chem. Commun. 66 (2001) 382.
ˇ
ˇ
´
´
´ˇ
´
[6] L. S’tastna, K. Auerova, J. Kvıcala, J. Cermak, J. Organomet. Chem.,
CCDC 614541 contains the supplementary crystallo-
graphic data for 6. These data can be obtained free of
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.
html, or from the Cambridge Crystallographic Data Cen-
tre, 12 Union Road, Cambridge CB2 1EZ, UK; fax:
(+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.jorganchem.
2006.12.004.
submitted for publication.
[7] A. Altomare, M.C. Burla, M. Camalli, G. Cascarano, C. Giaco-
vazzo, A. Guagliardi, G. Polidori, J. Appl. Crystallogr. 27 (1994)
435.
[8] D.J. Watkin, C.K. Prout, R.J. Carruthers, P. Betteridge, Crystals 10
(1996).
[9] (a) J.W. Kang, K. Moseley, P.M. Maitlis, J. Am. Chem. Soc. 91
(1969) 5970;
(b) W.D. Jones, F.J. Feher, Inorg. Chem. 23 (1984) 2376;
(c) W.D. Jones, V.L. Kuykendall, Inorg. Chem. 30 (1991) 2615.
[10] (a) W. Rigby, J.A. McCleverty, P.M. Maitlis, J. Chem. Soc., Dalton
Trans. (1979) 382;
References
´
´
(b) G. Sanchez, I. Solano, M.D. Santana, G. Garcia, J. Galvez, G.
´
Lopez, Thermochim. Acta 211 (1992) 163;
[1] A. Togni, R.L. Halterman (Eds.), Metallocenes, vol. I, Wiley-VCH,
Weinheim, Germany, 1996, vol. II, 1998.
´
´
´
´
´
(c) G. Sanchez, J. Garcıa, J. Perez, G. Garcıa, G. Lopez, Thermo-
chim. Acta 307 (1997) 127.

ˇ
J. Cerma´k et al. / Journal of Organometallic Chemistry 692 (2007) 1557–1570
1570
[11] (a) W.D. Jones, F.J. Feher, Acc. Chem. Res. 22 (1989) 91;
(b) B.H. Weiller, E.P. Wasserman, R.G. Bergman, C.B. Moore,
G.C. Pimentel, J. Am. Chem. Soc. 111 (1989) 8288;
(c) B.K. Corkey, F.L. Taw, R.G. Bergman, M. Brookhart, Poly-
hedron 23 (2004) 2943.
[12] J. Sandstro¨m, Dynamic NMR Spectroscopy, Academic Press, New
York, 1982, p. 79.
[13] P.J. Stang, B. Olenyuk, A.M. Arif, Organometallics 14 (1995)
5281.
[14] U. Bierbach, N. Farrell, Inorg. Chem. 36 (1997) 3657.