Cationic rhodium(I) and iridium(I) α-diimine complexes

Article abstract of DOI:10.1016/j.poly.2011.11.058

Condensation of glyoxal with fluoroarylanilines [Ar^FNH ₂; Ar^F = 4-C₆H₄F; 2,4-C ₆H₃F₂; 2,4,6-C₆H₂F ₃] generates new fluorine-substitute

Full text of DOI:10.1016/j.poly.2011.11.058

Polyhedron 33 (2012) 360–366
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Cationic rhodium(I) and iridium(I) a-diimine complexes
⇑
Duncan A.J. Harding, Eric G. Hope , Kuldip Singh, Gregory A. Solan
Department of Chemistry, University of Leicester, Leicester LE1 7RH, UK
a r t i c l e i n f o
a b s t r a c t
Condensation of glyoxal with fluoroarylanilines [ArFNH2; ArF = 4-C6H4F; 2,4-C6H3F2; 2,4,6-C6H2F3] gener-
Article history:
ates new fluorine-substituted aryl
been structurally characterised. Displacement of acetonitrile from [M(COD)(MeCN)2][BF4] (M = Rh, Ir,
COD = 1,5-cyclooctadiene) with fluorine- and non-fluorine-substituted aryl -diimines yields cationic
rhodium(I) and iridium(I) complexes, that can be carbonylated to [M(CO)2( -diimine)][BF4].
a
-diimines, ArFNCH@CHNArF; ArF = 4-C6H4F and 2,4,6-C6H2F3 have
Received 21 November 2011
Accepted 27 November 2011
Available online 11 December 2011
a
a
Keywords:
Ó 2011 Elsevier Ltd. All rights reserved.
a-Diimines
Fluorine
Rhodium
Iridium
Organometallic
Crystal structures
1. Introduction
(ArF = 4-C6H4F, 2,4-C6H3F2, 2,4,6-C6H2F3), and their cationic rho-
dium(I) complexes.
The renewed attention that late transition metal 1,4-diazabut-
adiene (
in regard to their value in olefin polymerisation chemistry [1,2],
has led us to investigate exploiting the power of the -diimine li-
a-diimine) complexes have received recently, particularly
2. Results and discussion
a
gand set to stabilise late transition metal fluoride complexes of
rhodium and iridium [3,4]. Previously, a few square planar cationic
The non-fluorinated glyoxal
used in this study were readily prepared by literature routes
[18–20]. Surprisingly, the first glyoxal fluoroaryl -diimines have
a-diimines (L1–L4) (Scheme 1)
rhodium [5–7]
a-diimine systems had been described that ap-
a
peared potentially amenable to oxidative fluorination chemistry,
and here we describe the synthesis of a series of new cationic rho-
dium(I) and iridium(I) complexes with COD (COD = 1,5-cycloocta-
diene) and CO co-ligands. We also have a long-standing interest
in the coordination properties of fluorine-containing ligands and
have investigated a broad range of F-substituted ligands, including
triarylphosphines [8,9], triarylphosphites [10], phenylimides [11],
b-diketonates [12], phenylphosphonates [13], dithiophosphates
only very recently been reported in the literature [17]. Cowley
and co-workers [16,21] have speculated that these derivatives
may be difficult to prepare via the conventional condensation
route as a consequence of the electronegative fluorine atoms. As
an alternative, a structurally characterised series of fluoroarylimi-
doalane derivatives were prepared as potential activated interme-
diates in the generation of fluoroaryl
a-diimines and their use in
the preparation of fluoroaryl -diimines based on the 2,3-butane-
a
[14] and xanthates [15]. Only four fluoroaryl
a
-diimine ligands
dione backbone was reported. In this work, as suggested by
Cowley, the reaction of fluorinated anilines with glyoxal is slow
but, by increasing the reaction temperatures and reaction times,
have been reported previously [16,17]. ArFNC(Me)C(Me)NArF
(ArF = 4-C6H4F, 3,5-C6H3F2, C6F5) are formed via aminoalane reac-
tions with 2,3-butanedione [16], and ArFNCHCHNArF (ArF = 2,6-di-
methyl-4-fluorophenyl) has been prepared as an intermediate in a
study on the influence of electronic properties of NHC ligands on
the catalytic activity of Grubbs II metathesis catalysts [17]. As part
of this study, we also describe the synthesis and characterisation of
the new fluoroaryl
a
-diimines (ArFNCH@CHNArF; ArF = 4-C6H4F
(L5), 2,4-C6H3F2 (L6), 2,4,6-C6H2F3 (L7)) could be isolated directly
in reasonable yields without the need to exploit the greater reac-
tivity of the imidoalane derivatives. These new imines were char-
acterised by multinuclear NMR spectroscopy, IR spectroscopy,
mass spectrometry, elemental analyses and in addition, for L5
and L7, by single crystal X-ray diffraction.
a set of related fluoroaryl
a
-diimine ligands, ArFNCHCHNArF
Crystals of L5 and L7 suitable for the X-ray determination were
grown by slow evaporation of THF solutions. A view of L7 is shown
in Fig. 1 as a representative example; lists of bond lengths and an-
gles for L5 and L7 can be found in the Supplementary material. The
⇑
Corresponding author. Tel.: +44 116 252 2108; fax: +44 116 252 3789.
E-mail address: egh1@le.ac.uk (E.G. Hope).
0277-5387/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2011.11.058

D.A.J. Harding et al. / Polyhedron 33 (2012) 360–366
361
Scheme 1. Synthetic route to cationic and rhodium complexes 1–15.
Fig. 1. Molecular structure of L7 with 30% displacement ellipsoids.
molecule lies on a crystallographic centre of inversion and hence
the two imine groups are s-trans, as has been observed in other
systems [16,22,23]. The crystallographic data suggests that the
NAr)]+[BF4]À {M = Rh, Ar = 2,4,6-Me3C6H2 (1), 2,6-iPr2C6H3 (2), 2,6-
Me2C6H3 (3), 4-C6H4F (4), 2,4-F2C6H3 (5), M = Ir, Ar = 2,4,6-Me3C6H2
(6), 2,6-iPr2C6H3 (7)} and [Ir(COD)(AdamantylNCHCHNAdaman-
tyl)]+[BF4]À (8) in good yields (Scheme 1). Carbonylation of com-
plexes (1, 2, 3, 4, 6–8) at ambient temperatures generated the
new carbonyl complexes [M(CO)2(ArNCHCHNAr)]+[BF4]À {M = Rh,
Ar = 2,4,6-Me3C6H2 (9), 2,6-iPr2C6H3 (10), 2,6-Me2C6H3 (11), 4-
C6H4F (12); M = Ir, Ar = 2,4,6-Me3C6H2 (13), 2,6-iPr2C6H3 (14)}
and [Ir(CO)2(AdamantylNCHCHNAdamantyl)]+[BF4]À (15) in quan-
titative yield (Scheme 1). All complexes were characterised by
multinuclear NMR spectroscopies, mass spectrometry, IR spectros-
copy and, for selected examples, elemental analyses (see Table 1
and Section 4).
environment around the imine bonds in these fluoroaryl
a-dii-
mines and the related mesityl [24] and pentafluorophenyl [16]
analogues appears relatively insensitive to the substituents on
the aryl rings, with modest shortening in the aryl-N bond with
increasing numbers of fluorine substituents. In contrast, the values
of mCN, d(NCH) and d(NCH) exhibit definite trends. As the number of
electron-withdrawing fluorine atoms on the aryl rings increases,
the values of mCN [1605 cmÀ1 (L5), 1603 cmÀ1 (L6), 1589 cmÀ1
(L7)] decrease and d(NCH) [d 159.3 (L5), d 161.4 (L6)] and d(NCH)
[d 8.35 (L5), d 8.49 (L6), d 8.52 (L7)] shift to lower field, indicating
a change in the electronic environment and a weakening of the
imine bond.
For all the COD complexes (1–8), as expected mCN decreases on
coordination due to a mild degree of backbonding from the metal
into the p⁄ orbitals of the imine [25]. Indeed, a theoretical study
[26] on metal to ligand electron transfer in bis(imino)pyridine
complexes of the first row transition metals (Mn to Zn) has
The displacement of acetonitrile from [M(COD)(MeCN)2]+[BF4]À
(M = Rh, Ir) with
a-diimines was facile, affording a series of new
rhodium(I) and iridium(I) cationic complexes [M(COD)(ArNCHCH-

362
D.A.J. Harding et al. / Polyhedron 33 (2012) 360–366
Table 1
and 2.074(2) Å], while a distinct variation is apparent in the former
Selected spectroscopic data for rhodium and iridium aryl
a-diimine complexes.
complex [2.053(2) and 1.966(2) Å] reflecting the differing nature of
the trans ligands. On the other hand, for the bisadamantylimine
complex 15 there is asymmetry in the metal carbonyl bond lengths
[1.836(9) and 1.866(10) Å], arising from relatively short interac-
tions with the tetrafluoroborate anion (O(2)ÁÁÁF(2) 3.213 Å,
O(1)ÁÁÁF(3) 3.406 Å); in 14 the cation and anion are discrete. Fur-
thermore, the iridium–nitrogen(imine) bond lengths in 15 are
longer [2.111(6) and 2.117(7) Å] than those for 14 reflecting the
poorer donor properties for the bisadamantylimine ligand.
m
(CN) (cmÀ1
)
m
(CO) (cmÀ1
)
d(NCH) (ppm)
[Rh(COD)(L1)]+[BF4]À (1)
[Rh(COD)(L2)]+[BF4]À (2)
[Rh(COD)(L3)]+[BF4]À (3)
[Rh(COD)(L5)]+[BF4]À (4)
[Rh(COD)(L6)]+[BF4]À (5)
[Ir(COD)(L1)]+[BF4]À (6)
[Ir(COD)(L2)]+[BF4]À (7)
[Ir(COD)(L4)]+[BF4]À (8)
[Rh(CO)2(L1)]+[BF4]À (9)
[Rh(CO)2(L2)]+[BF4]À (10)
[Rh(CO)2(L3)]+[BF4]À (11)
[Rh(CO)2(L5)]+[BF4]À (12)
[Ir(CO)2(L1)]+[BF4]À (13)
[Ir(CO)2(L2)]+[BF4]À (14)
[Ir(CO)2(L4)]+[BF4]À (15)
1592
1608
1591
1592
1597
1614
1611
1634
1623
1620
1622
1594
1619
1618
1629
–
–
–
–
–
–
–
–
8.15
8.35
8.23
8.14
8.54
8.76
9.03
8.84
8.31
8.43
8.42
8.35
8.68
8.97
8.82
2109, 2071
2102, 2041
2107, 2067
2103, 2053
2095, 2025
2089, 2023
2076, 2004
3. Conclusions
Three new fluoroaryl a-diimines have been synthesised by con-
densation of glyoxal with fluorinated anilines at elevated temper-
atures. X-ray structural characterisations reveal that these adopt
an E geometry at the imino unit. The new fluoroaryl
and related non-fluorinated ligands, coordinate to rhodium(I) and
iridium(I) centres to generate stable -diimine-COD and -dii-
mine-CO cationic complexes that are valuable derivatives for fur-
ther synthetic chemistry.
a-diimines,
indicated that such synergic bonding may be of more importance
in imine coordination than previously thought. The same trends
are observed for the metal complexes with both the fluorinated
a
a
and non-fluorinated a-diimines (4, 5). In contrast, the greater com-
petition for backbonding in the carbonyl complexes (9–15) leaves
mCN virtually unaltered from those for the free ligands. There are
no discernible trends in the NMR parameters, d(NCH) and
d(NCH), on coordination.
Complexes 14 and 15 were also the subject of single crystal
X-ray diffraction studies; suitable crystals for the studies could
be grown by slow evaporation from dichloromethane solutions.
Perspective views of the complexes are shown in Figs. 2 and 3; se-
lected bond lengths and angles collected in Table 2. As expected
the cationic unit in both iridium(I) complexes display square pla-
nar geometries with the carbonyl ligands configured mutually cis.
4. Experimental
4.1. General experimental procedures
Proton, 13C and 19F NMR spectroscopic studies were carried out
on
a Bruker DPX300 spectrometer at 300.14, 75.47 and
282.41 MHz. All chemical shifts are quoted in ppm using the high-
frequency positive convention; 1H and 13C NMR spectra were refer-
enced to external SiMe4 and 19F NMR spectra to external CFCl3. Ele-
mental analyses were performed either by the Elemental Analysis
Service at the London Metropolitan University. Mass spectra were
recorded on a Kratos Concept 1H mass spectrometer. IR spectra were
recorded as solid samples on a Perkin Elmer Spectrum One FT-IR
spectrometer. 1,4-Bis(2,4,6-trimethylphenyl)-1,4-diaza-1,3-buta-
diene (L1), 1,4-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene
(L2), 1,4-bis(2,6-dimethylphenyl)-1,4-diaza-1,3-butadiene (L3)
While a number of iridium(III) complexes containing a-diimine li-
gands have been previously reported [27,28], the only crystallo-
graphically characterised example of an iridium(I) species to date
is neutral [IrCl(CNtBu)(2,6-Me2C6H3NCMeCMeN-2,6-Me2C6H3)]
[29]. In comparison with [IrCl(CNtBu)(2,6-Me2C6H3NCMeCMeN-
2,6-Me2C6H3)], the Ir–N bond lengths in 14 are similar [2.080(2)
À
Fig. 2. Molecular structure of the cationic unit in 14 with 30% displacement ellipsoids. H atoms and BF4 anion have been omitted for clarity.

D.A.J. Harding et al. / Polyhedron 33 (2012) 360–366
363
Fig. 3. Molecular structure of 15 with 30% displacement ellipsoids; dotted lines show OÁÁÁF interactions. H atoms and lattice CH2Cl2 have been omitted for clarity.
(FAB) 245 ([MH]+). Acc. Mass: C14H11F2N2 ([MH]+), requires
245.08903, found 245.08900.
Table 2
Selected bond length (Å) and bond angle (o) data for 14 and 15.
[Ir(CO)2(RNCHCHNR)]+[BF4]À
R = 2,6-C6H3iPr2 (14)
R = adamantyl (15)
4.3. Synthesis of 1,4-bis(2,4-difluorophenyl)-1,4-diaza-1,3-butadiene
(L6)
Bond lengths
Ir(1)–C(1)
Ir(1)–C(2)
Ir(1)–N(1)
Ir(1)–N(2)
N(1)–C(3)
N(2)–C(4)
N(1)–C(5)
N(2)–C(17/C12)
C(1)–O(1)
C(1)–O(2)
Av B–F
1.866(3)
1.861(3)
2.080(2)
2.074(2)
1.270(2)
1.279(3)
1.452(3)
1.458(3)
1.134(3)
1.136(3)
1.388
1.836(9)
1.866(10)
2.111(6)
2.117(7)
1.277(10)
1.264(10)
1.488(9)
1.502(10)
1.141(10)
1.124(10)
1.354
The title compound was isolated in a similar manner. M.p. 147–
149 °C.
m
max/cmÀ1 3378br, 1603s (CN), 1505vs, 1429s, 1262s,
1141s, 957s, 848s, 800s, 722s (solid state). 1H NMR (CDCl3): 8.49
(s, 2H, NCHCH), 7.29 (m, 2H, 3-CH), 6.95 (m, 4H, 5-/6-CH).
19F{1H} (CDCl3): À109.5 (s, 2F, 2-CF), À119.0 (s, 2F, 4-CF). 13C
1
3
NMR (CDCl3): 162.2 (dd, JCF = 251 Hz, JCF = 11 Hz, 4-C), 161.4 (s,
1
3
HCN), 156.1 (dd, JCF = 256 Hz, JCF = 12 Hz, 2-C), 134.2 (d,
2JCF = 10 Hz, 1-C), 122.4 (d, JCF = 9 Hz, 6-C), 111.9 (d, JCF = 22 Hz,
3
2
Bond angles
5-C), 105.2 (t, 2JCF = 25 Hz, 3-C). m/z (+FAB) 281 ([MH]+). Acc. Mass:
C(1)–Ir(1)–C(2)
N(1)–Ir(1)–N(2)
N(1)–C(3)–C(4)
N(2)–C(4)–C(3)
90.11(12)
77.60(9)
116.5(3)
116.0(3)
84.5(4)
78.0(3)
117.6(7)
118.7(8)
C
14H9F4N2 ([MH]+), requires 281.07028, found 281.07019.
4.4. Synthesis of 1,4-bis(2,4,6-trifluorophenyl)-1,4-diaza-1,3-
butadiene (L7)
and 1,4-bisadamantyl-1,4-diaza-1,3-butadiene (L4) were prepared
by the literature routes [18–20].
The title compound was isolated in a similar manner. M.p. 163–
165 °C. Anal. Calc. for C14H6F6N2: C, 53.16; H, 1.91; N, 8.86. Found:
C, 53.23; H, 1.85; N, 8.75%. m
max/cmÀ1 3104br, 1589s (CN), 1508s,
1485s, 1446s, 1116s, 1038s, 996s, 845s, 786s, 724s, 654br. 1H
4.2. Synthesis of 1,4-bis(4-fluorophenyl)-1,4-diaza-1,3-butadiene (L5)
3
NMR (CDCl3): 8.52 (s, 2H, NCHCH), 6.73 (t, 2H, JHF = 8.4 Hz, 3-
CH). 19F{1H} NMR (CDCl3): À108.8 (s, 4F, 2-CF), À118.9 (s, 2F, 4-
CF). m/z (FAB) 317 ([MH]+). Acc. Mass: C14H7F6N2 ([MH]+), requires
317.05134, found 317.05140.
A solution of glyoxal (19.620 g of a 40% aqueous solution,
135 mmol) in n-propanol (50 cm3) was added slowly to a stirred
solution of para-fluoroaniline (30.000 g, 270 mmol) in n-propanol
(50 cm3) at room temperature. Once addition was complete, the
yellow solution was heated to 60 °C for 3 h. The volume of solvent
was reduced in vacuo to ca. 15 cm3, and the resulting yellow pre-
cipitate was collected by filtration and washed with ice-cold meth-
anol, giving the product as a pale yellow powder in 52% yield. M.p.
128–129 °C. Anal. Calc. for C14H10F2N2: C, 68.83; H, 4.13; N, 11.47.
4.5. Synthesis of [Rh(COD)(L1)][BF4] (1)
A solution of L1 (154 mg, 0.526 mmol) in dichloromethane
(5 cm3) was added dropwise at room temperature to a stirred solu-
tion of [Rh(COD)(MeCN)2]+[BF4]À (200 mg, 0.526 mmol) in dichloro-
methane (5 cm3). Stirring was continued for 6 h, after which the
deep green solution was added to diethyl ether (200 cm3). The
resulting deep green solid was recrystallised from dichlorometh-
ane/hexane, giving the product as an air-sensitive green solid in
92% yield. Anal. Calc. for C28H36BF4N2Rh: C, 56.93; H, 6.15; N, 4.75.
Found: C, 68.81; H, 4.06; N, 11.49%.
m
max/cmÀ1 1605s (CN), 1557w,
1496s, 1031s, 1221s, 1156s, 826s. 1H NMR (CDCl3): 8.35 (s, 2H,
3
3
NCHCH), 7.31 (dd, 4H, JHH = 8.5 Hz, JHF = 4.0 Hz, 3-CH), 7.15 (d,
3
4H, JHH = 8.5 Hz, 2-CH). 19F{1H} (CDCl3): À113.7 (s, 4-CF). 13C
1
NMR (CDCl3): 162.4 (d, JCF = 248 Hz, 4-C), 159.3 (s, HCN), 146.0
3
2
(s, 1-C), 123.0 (d, JCF = 9 Hz, 2-C), 116.3 (d, JCF = 23 Hz, 3-C). m/z
Found: C, 56.95; H, 5.97; N, 4.87%. m
max/cmÀ1 2911br, 1592br (CN),

364
D.A.J. Harding et al. / Polyhedron 33 (2012) 360–366
1477s, 1206s, 1029br ([BF4]À), 842s. 1H NMR (CDCl3): 8.15 (br s, 2H,
NCHCHN), 6.85 (s, 4H, Ar-CH), 3.75 (br s, 4H, COD-CH), 2.38–2.22 (m,
16H, ortho-Ar-CH3 and COD-CH2), 2.21 (s, 6H, para-Ar-CH3), 1.88 (m,
4H, COD-CH2). 19F{1H} NMR (CDCl3): À152.0 (s, [BF4]À). m/z (FAB)
503 ([MÀBF4]+), 395 ([MÀBF4-COD]+).
2958s, 1611br (CN), 1457s, 1435w, 1365s, 1030s ([BF4]À) (solid
state). 1H NMR (CDCl3): 9.03 (s, 2H, NCHCHN), 7.29 (t, 2H,
3
3JHH = 8.8 Hz, para-CH), 7.20 (d, 4H, JHH = 8.9 Hz, meta-CH), 4.08
3
(br s, 4H, COD-CH), 3.12 (sep, 4H, JHH = 6.9 Hz, CH3CH), 2.10–1.55
3
(m, 8H, COD-CH2), 1.35 (d, 12H, JHH = 6.9 Hz, CH3CH), 1.17 (d,
3
12H, JHH = 6.9 Hz, CH3CH). 19F{1H} NMR (CDCl3): À152.2 (s,
4.6. Synthesis of [Rh(COD)(L2)][BF4] (2)
[BF4]À). m/z (FAB) 677 ([MÀBF4]+).
The title compound was isolated in a similar manner. Anal. Calc.
4.12. Synthesis of [Ir(COD)(L4)][BF4] (8)
for C34H48BF4N2Rh: C, 60.51; H, 7.17; N, 4.15. Found: C, 60.57; H,
7.04; N, 4.07%.
m
max/cmÀ1 2964s, 1608br (CN), 1552w, 1461s,
The title compound was isolated in a similar manner. NMR
1368s, 1056vs ([BF4]À), 806s. 1H NMR (CDCl3): 8.35 (br s, 2H,
spectra were recorded at À60 °C. Anal. Calc. for C30H44BF4IrN2: C,
3
NCHCHN), 7.25 (t, 2H, JHH = 6.8 Hz, para-Ar-CH), 7.18 (d, 4H,
50.59; H, 6.23; N, 3.94. Found: C, 50.68; H, 6.05; N, 4.02%. mmax
/
3JHH = 6.9 Hz, meta-Ar-CH), 3.84 (br s, 4H, COD-CH), 3.22 (sep, 4H,
3JHH = 6.8 Hz, CH3CH), 2.29 (m, 4H, COD-CH2), 1.89 (m, 4H, COD-
CH2), 1.40 (d, 12H, 3JHH = 6.7 Hz, CH3CH), 1.16 (d, 12H, 3JHH = 6.7 Hz,
CH3CH). 19F{1H} NMR (CDCl3): À151.8 (s, [BF4]À). m/z (FAB) 587
([MÀBF4]+), 479 ([MÀBF4ÀCOD]+).
cmÀ1 2908s, 2857s, 1634br (CN), 1452m, 1365m, 1306m, 1054vs
([BF4]À) (solid state). 1H NMR (CDCl3): 8.84 (s, 2H, NCHCHN),
3.89 (br s, 4H, COD-CH), 2.30–1.50 (m, 38H, Ada-CH2/CH and
COD-CH2). 19F{1H} NMR (CDCl3): À150.6 (s, [BF4]À). m/z (FAB)
625 ([MÀBF4]+), 517 ([MÀBF4ÀCOD]+).
4.7. Synthesis of [Rh(COD)(L3)][BF4] (3)
4.13. Synthesis of [Rh(CO)2(L1)][BF4] (9)
The title compound was isolated in a similar manner. Anal. Calc.
for C26H32BF4N2Rh: C, 55.50; H, 5.74; N, 4.98. Found: C, 55.64; H,
Carbon monoxide was bubbled through a stirred solution of 1
(200 mg, 0.339 mmol) in dichloromethane (5 cm3) at room tem-
perature for 30 min, after which the red solution was poured into
diethyl ether (200 cm3). The precipitate was collected and recrys-
tallised from dichloromethane/hexane, giving the product as air-
sensitive deep red needles in quantitative yield. Anal. Calc. for
5.93; N, 4.96%.
m
max/cmÀ1 1591s (CN), 1471s, 1431s, 1199s,
1045br ([BF4]À). 1H NMR (CDCl3): 8.23 (br s, 2H, NCHCHN), 7.06
(m, 6H, ArH), 3.76 (s, 4H, COD-CH), 2.35 (m, 16H, Ar-CH3 and
COD-CH2), 1.89 (m, 4H, COD-CH2). 19F{1H} NMR (CDCl3): À152.0
(s, [BF4]À). m/z (FAB) 475 ([MÀBF4]+).
C
22H24BF4N2O2Rh: C, 49.06; H, 4.50; N, 5.20. Found: C, 49.04; H,
4.56; N, 5.26%.
m
max/cmÀ1 2109s (CO), 2071s (CO), 1623s (CN),
4.8. Synthesis of [Rh(COD)(L5)][BF4] (4)
1606s (CN), 1480br, 1212s, 1052vs ([BF4]À). 1H NMR (CDCl3):
8.31 (br s, 2H, NCHCHN), 6.94 (m, 4H, meta-Ar-CH), 2.32 (s, 12H,
ortho-CH3), 2.25 (s, 6H, para-CH3). 19F NMR (CDCl3): À151.2 (s,
[BF4]À). m/z (+FAB) 451 ([MÀBF4]+), 423 ([MÀBF4ÀCO]+), 395
([MÀBF4À2CO]+).
The title compound was isolated in a similar manner. m
max/cmÀ1
2922w, 1592s (CN), 1492s, 1231br, 1030s ([BF4]À), 840s. 1H NMR
(CDCl3): 8.14 (br s, 2H, NCHCHN), 7.22 (m, 4H, meta-Ar-CH), 7.10
3
(d, 4H, JHH = 8.1 Hz, ortho-Ar-CH), 4.05 (br s, 4H, COD-CH), 2.37
(m, 4H, COD-CH2), 1.85 (m, 4H, COD-CH2). 19F{1H} NMR (CDCl3):
À111.8 (s, 2F, 4-CF), À149.8 (s, 4F, [BF4]À). m/z (FAB) 455
([MÀBF4]+), 347 ([MÀBF4ÀCOD]+).
4.14. Synthesis of [Rh(CO)2(L2)][BF4] (10)
The title compound was isolated in a similar manner. Anal. Calc.
for C28H36BF4N2O2Rh: C, 54.00; H, 5.83; N, 4.50. Found: C, 54.20; H,
4.9. Synthesis of [Rh(COD)(L6)][BF4] (5)
5.68; N, 4.42%. m
max/cmÀ1 2965br, 2102s (CO), 2041s (CO), 1620w
(CN), 1589w (CN), 1462s, 1360s, 1033vs ([BF4]À), 796s, 751s. 1H
The title compound was isolated in a similar manner. Anal. Calc.
3
NMR (CDCl3): 8.43 (br s, 2H, NCHCHN), 7.36 (t, 2H, JHH = 7.5 Hz,
for C22H20BF8N2Rh: C, 45.67; H, 3.49; N, 4.84. Found: C, 45.74; H,
3
para-Ar-CH), 7.3 (d, 4H, JHH = 7.6 Hz, meta-Ar-CH), 3.20 (sep, 4H,
3.51; N, 4.80%. m
max/cmÀ1 1597s (CN), 1500s, 1240br, 1159s, 1032s
3
3JHH = 6.7 Hz, CH3CH), 1.35 (d, 12H, JHH = 6.7 Hz, CH3CH), 1.21 (d,
([BF4]À). 1H NMR (d6-DMSO): 8.54 (s, 2H, NCHCHN), 7.63 (m, 2H,
ArH), 7.42 (m, 2H, ArH), 7.18 (m, 2H, ArH), 4.00 (br s, 4H, COD-CH),
2.42 (m, 4H, COD-CH2), 1.71 (m, 4H, COD-CH2). 19F{1H} NMR (d6-
DMSO): À110.1 (s, 2F, 2-CF), À119.0 (s, 2F, 4-CF), À148.2 (s, 4F,
[BF4]À). m/z (FAB) 491 ([MÀBF4]+), 383 ([MÀBF4ÀCOD]+).
3
12H, JHH = 6.5 Hz, CH3CH). 19F{1H} NMR (CDCl3): À151.1 (s,
[BF4]À). m/z (FAB) 535 ([MÀBF4]+), 507 ([MÀBF4ÀCO]+), 479
([MÀBF4À2CO]+).
4.15. Synthesis of [Rh(CO)2(L3)][BF4] (11)
4.10. Synthesis of [Ir(COD)(L1)][BF4] (6)
The title compound was isolated in a similar manner. m
max/cmÀ1
2107s (CO), 2067s (CO), 1622m (CN), 1472s, 1201s, 1023vs
([BF4]À), 779s. 1H NMR (CDCl3): 8.42 (br s, 2H, NCHCHN), 7.05
(m, 6H, meta-Ar-CH), 2.38 (s, 12H, CH3). 19F{1H} NMR (CDCl3):
À150.7 (s, [BF4]À). m/z (+FAB) 423 ([MÀBF4]+), 395 ([MÀBF4ÀCO]+),
367 ([MÀBF4À2CO]+).
The title compound was isolated in a similar manner. NMR
spectra were recorded at À60 °C. Anal. Calc. for C28H36BF4IrN2: C,
49.45; H, 5.34; N, 4.12. Found: C, 49.59; H, 5.27; N, 4.10%. mmax
/
cmÀ1 2924w, 1614br (CN), 1480br, 1385s, 1215s, 1028s ([BF4]À)
(solid state). 1H NMR (CDCl3): 8.76 (s, 2H, NCHCHN), 6.87 (s, 4H,
meta-CH), 3.92 (br s, 4H, COD-CH), 2.24 (s, 12H, ortho-CH3), 2.09
(s, 6H, para-CH3), 2.15–1.60 (m, 8H, COD-CH2). 19F{1H} NMR
(CDCl3); À152.1 (s, [BF4]À). m/z (FAB) 593 ([MÀBF4]+).
4.16. Synthesis of [Rh(CO)2(L5)][BF4] (12)
The title compound was isolated in a similar manner. m
max/cmÀ1
4.11. Synthesis of [Ir(COD)(L2)][BF4] (7)
2103s (CO), 2053s (CO), 1594s (CN), 1498s, 1239s, 1035vs ([BF4]À),
843s. 1H NMR (CDCl3): 8.35 (br s, 2H, NCHCHN), 7.52 (m, 4H, meta-
3
The title compound was isolated in a similar manner. NMR spec-
Ar-CH), 7.17 (d, 4H, JHH = 8.1 Hz, ortho-Ar-CH). 19F{1H} NMR
tra were recorded at À60 °C. Anal. Calc. for C34H48BF4IrN2.CH2Cl2: C,
(CDCl3): À108.0 (s, 2F, 4-CF), À149.1 (s, 4F, [BF4]À). m/z (+FAB)
403 ([MÀBF4]+), 375 ([MÀBF4ÀCO]+), 347 ([MÀBF4À2CO]+).
49.50; H, 5.94; N, 3.30. Found: C, 49.95; H, 5.84; N, 3.32%. m
max/cmÀ1

D.A.J. Harding et al. / Polyhedron 33 (2012) 360–366
365
Table 3
Crystal data and structure refinement of compounds L5, L7, 14 and 15.
L5
L7
14
15
Formula
Formula weight
T (K)
C
l4H10F2N2
Cl4H6F6N2
316.21
150(2)
C28H36BF4IrN2O2
711.60
150(2)
C25H34BCl2F4IrN2O2
744.45
150(2)
244.24
150(2)
k (Å)
0.71073
0.71073
monoclinic
P2(1)/c
0.71073
monoclinic
P2(1)/c
0.71073
orthorhombic
Pnma
Crystal system
Space group
Unit cell dimensions
a (Å)
b (Å)
c (Å)
triclinic
ꢀ
P1
3.9447(19)
6.687(3)
11.583(6)
102.716(7)
94.496(8)
106.790(7)
282.0(2)
1
1. 438
0.110
126
0.29 Â 0.10 Â 0.05
1.82–25.00
À4 6 h 6 4, À7 6 k 6 7,
À13 6 l 6 13
1999
3.8927(5)
5.8614(7)
25.979(3)
90
91.767(2)
90
592.48(13)
2
1.772
10.7944(15)
13.8734(19)
19.928(3)
90
102.544(2)
90
2913.1(7)
4
23.76(3)
6.671(9)
17.18(2)
90
90
90
2723(6)
4
a
(°)
b (°)
c
(°)
U (Å3)
Z
Dcalc (mg mÀ3
)
1.623
4.636
1408
1.816
5.154
1464
l
(Mo K
F(000)
Dimensions (mm)
a
) (mmÀ1
)
0.173
316
0.38 Â 0.12 Â 0.09
1.57–25.00
À4 6 h 6 4, À6 6 k 6 6,
À30 6 l 6 30
4090
0.35 Â 0.16 Â 0.12
1.60–26.00
À13 6 h 6 13, À17 6 k 6 16,
À24 6 l 6 24
22562
0.26 Â 0.05 Â 0.03
1.46–26.00
À29 6 h 6 28, À8 6 k 6 8,
À21 6 l 6 21
19575
Data collection range (°)
Data collection range
Reflections
Unique reflections
Rint
978
0.0475
1048
0.0234
5719
0.0304
2920
0.0935
Completeness of data (%)
Absorption correction
Maximum/minimum
transmission factors
Data/restraints/parameters
Goodness of fit on F2
98.9
empirical
0.96/0.82
99.8
empirical
0.96/9.75
99.9
empirical
0.928/0.585
100.0
integration
0.8252/0.4306
978/0/82
0.968
1048/0/100
1.040
5719/0/351
0.970
2920/0/202
1.043
Final R indices [I > 2
R indices all data
r
(I)]
R1 = 0.0499, wR2 = 0.1258
R1 = 0.0660, wR2 = 0.1333
R1 = 0.0330, wR2 = 0.0806
R1 = 0.0394, wR2 = 0.0839
0.215/À0.192
R1 = 0.0218, wR2 = 0.0497
R1 = 0.0251, wR2 = 0.0506
1.586/À0.8533
R1 = 0.0395, wR2 = 0.0928
R1 = 0.0545, wR2 = 0.0978
1.774/À1.363
Largest difference peak and hole 0.253/À0.293
(e ÅÀ3
)
4.17. Synthesis of [Ir(CO)2(L1)][BF4] (13)
(CDCl3): À149.6 (s, [BF4]À). m/z (FAB) 573 ([MÀBF4]+), 545
([MÀBF4ÀCO]+), 517 ([MÀBF4À2CO]+).
The title compound was isolated in a similar manner. Anal. Calc.
for C22H24BF4IrN2O2: C, 42.08; H, 3.86; N, 4.46. Found: C, 42.17; H,
4.20. X-ray crystallography
3.96; N, 4.47%. m
max/cmÀ1 2095s (CO), 2025s (CO), 1619br (CN),
1605br (CN), 1558w, 1501w, 1445w, 1212w, 1058s ([BF4]À). 1H
NMR (CDCl3): 8.68 (s, 2H, NCHCHN), 6.88 (s, 4H, meta-Ar-CH),
2.31 (s, 12H, ortho-Ar-CH3), 2.25 (s, 6H, para-Ar-CH3). 19F{1H}
NMR (CDCl3): À150.5 (s, [BF4]À). m/z (FAB) 541 ([MÀBF4]+), 513
([MÀBF4ÀCO]+).
Data for L5, L7, 14 and 15 were collected on a Bruker APEX 2000
CCD diffractometer using graphite-monochromated Mo K
a radia-
tion. Full details of the data collection and refinement are given
in Table 3. The data were corrected for Lorentz and polarisation ef-
fects and empirical corrections applied. Structure solution by direct
methods and structure refinement on F2 employed SHELXTL version
6.10 [30]. The C–H hydrogen atoms were included in calculated
positions (C–H = 0.95–1.00 Å) riding on the bonded atom with iso-
tropic displacement parameters set to 1.5 Ueq(C) for methyl H
atoms and 1.2 Ueq(C) for all other H atoms. All non-hydrogen atoms
were refined with anisotropic displacement parameters. Atomic
coordinates, bond lengths and angles for L5, L7, 14 and 15 are
available in the Supplementary crystallographic data; selected
bond lengths and angles for 14 and 15 are listed in Table 2.
4.18. Synthesis of [Ir(CO)2(L2)][BF4] (14)
The title compound was isolated in a similar manner. Anal. Calc.
for C28H36BF4IrN2O2: C, 47.22; H, 5.10; N, 3.94. Found: C, 47.27; H,
4.94; N, 3.83.
m
max/cmÀ1 2089s (CO), 2023s (CO), 1618br (CN),
1605br (CN), 1555w, 1500w, 1462br, 1361w, 1058s ([BF4]À). 1H
3
NMR (CDCl3): 8.97 (br s, 2H, NCHCHN), 7.35 (t, 2H, JHH = 7.2 Hz,
3
para-Ar-CH), 7.25 (d, 4H, JHH = 7.3 Hz, meta-Ar-CH), 3.19 (sep,
3
3
4H, JHH = 6.7 Hz, CH3CH), 1.34 (d, 12H, JHH = 6.9 Hz, CH3CH),
Acknowledgements
3
1.22 (d, 12H, JHH = 6.7 Hz, CH3CH). 19F{1H} NMR (CDCl3): À151.2
(s, [BF4]À). m/z (FAB) 625 ([MÀBF4]+), 597 ([MÀCO]+).
We thank EPSRC for financial support and Mr. James Taylor for
assistance with some of the experimental work.
4.19. Synthesis of [Ir(CO)2(L4)][BF4] (15)
Appendix A. Supplementary material
The title compound was isolated in a similar manner. Anal. Calc.
for C24H32BF4IrN2O2: C, 40.04; H, 3.36; N, 4.67. Found: C, 40.99; H,
CCDC 724968–724972 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or
from the Cambridge Crystallographic Data Centre, 12 Union Road,
3.53; N, 4.63%. m
max/cmÀ1 2912br, 2076s (CO), 2004s (CO), 1629br
(CN), 1453w, 1344w, 1034s ([BF4]À), 728s. 1H NMR (CDCl3): 8.82 (s,
2H, NCHCHN), 2.25–1.65 (m, 30H, Ada-CH2/CH). 19F{1H} NMR

366
D.A.J. Harding et al. / Polyhedron 33 (2012) 360–366
[14] J. Fawcett, E.G. Hope, A.M. Stuart, D.R.W. Wood, J. Fluorine Chem. 126 (2005)
507.
[15] J. Fawcett, E.G. Hope, A.M. Stuart, D.R.W. Wood, J. Fluorine Chem. 126 (2005)
1117.
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
[16] J.C. Gordon, P. Shukla, A.H. Cowley, J.N. Jones, D.W. Keogh, B.L. Scott, Chem.
Commun. (2002) 2710.
References
[17] S. Leuthäußer, V. Schmidts, C.M. Thiele, H. Plenio, Chem. Eur. J. 14 (2008) 5465.
[18] A.J. Arduengo, R. Krafczyk, R. Schmutzler, Tetrahedron 55 (1999) 14523.
[19] G.A. Grasa, M.S. Viciu, J. Huang, S.P. Nolan, J. Org. Chem. 66 (2001) 7729.
[20] H.T. Dieck, M. Svoboda, T. Greiser, Z. Naturforsch. 36b (1981) 823.
[21] P. Shukla, A.H. Cowley, J.N. Jones, J.C. Gordon, B.L. Scott, Dalton Trans. (2005)
1019.
[22] P.J. Albietz, K. Yang, E.J. Lachicotte, R. Eisenbery, Organometallics 19 (2000)
3543.
[23] I.A. Guzei, N.J. Hill, M.R. Van Hout, Acta Crystallogr., Sect. E 66 (2010) o40.
[24] T. Müller, B. Schrecke, M. Bolte, Acta Crystallogr., Sect. E 59 (2003) o1820.
[25] V.C. Gibson, C. Newton, C. Redshaw, G.A. Solan, A.J.P. White, D.J. Williams,
Dalton Trans. (2002) 4017.
[26] P.H.M. Budzelaar, B. De Bruin, A.W. Gal, Inorg. Chem. 40 (2001) 4649.
[27] S. Berger, F. Baumann, T. Scheiring, W. Kaim, Z. Anorg. Allg. Chem. 627 (2001)
620.
[28] S. Greulich, W. Kaim, A.F. Stange, H. Stoll, J. Fiedler, S. Záliš, Inorg. Chem. 35
(1996) 3998.
[29] A. Penner, T. Braun, Eur. J. Inorg. Chem. (2011) 2579.
[30] G.M. Sheldrick, SHELXTL, Version 6.10, Bruker AXS Inc., Madison, Wisconsin, USA,
2000.
[1] S.D. Ittel, L.K. Johnson, M. Brookhart, Chem. Rev. 100 (2000) 1169.
[2] Z. Guan, C.S. Popeney, in: Z. Guan (Ed.), Topics in Organometallic Chemistry,
vol. 26, Springer-Verlag, Berlin, 2009, p. 179.
[3] J. Fawcett, D.A.J. Harding, E.G. Hope, Dalton Trans. 39 (2010) 5827.
[4] D.A.J. Harding, Ph.D. Thesis, University of Leicester, 2006.
[5] E. Delgado-Laita, E. Sanchez-Munoyerro, Polyhedron 3 (1984) 799.
[6] B. Crociani, F. Di Bianca, M. Paci, T. Boschi, Inorg. Chim. Acta 145 (1988) 253.
[7] M. Bikrani, M.A. Garralda, L. Ibarlucea, E. Pinilla, M.R. Torres, Inorg. Chim. Acta
282 (1998) 230.
[8] M.J. Atherton, K.S. Coleman, J. Fawcett, J.H. Holloway, E.G. Hope, A. Karaçar,
D.R. Russell, G.C. Saunders, J. Chem. Soc., Dalton Trans. (1996) 3215.
[9] B. Croxtall, J. Fawcett, E.G. Hope, D.R. Russell, A.M. Stuart, J. Chem. Soc., Dalton
Trans. (2002) 491.
[10] M.J. Atherton, J. Fawcett, J.H. Holloway, E.G. Hope, D.R. Russell, G.C. Saunders, J.
Chem. Soc., Dalton Trans. (1997) 2217.
[11] P. Bhattacharyya, J. Fawcett, J.H. Holloway, E.G. Hope, G.C. Saunders, J. Chem.
Soc., Dalton Trans. (1997) 199.
[12] B. Croxtall, J. Fawcett, E.G. Hope, A.M. Stuart, J. Fluorine Chem. 119 (2003) 65.
[13] J.A. Bennett, E.G. Hope, K. Singh, A.M. Stuart, J. Fluorine Chem. 130 (2009) 615.