Rhodium(III) and iridium(III) half-sandwich complexes with tertiary arsine and stibine ligands

Article abstract of DOI:10.1016/j.jorganchem.2015.09.006

The syntheses of rhodium(III) and iridium(III) half-sandwich complexes containing tertiary arsine and stibine ligands of the form [Cp?M(L)Cl₂] (M = Rh, Ir; L = AsEt₃, AsPh₃, SbPh₃) are reported. These compounds represent infrequent examples of rhodium and iridium metal complexes bearing arsenic or antimony ligands. All new compounds were fully characterised using ¹H and ¹³C NMR spectroscopy, mass spectrometry and single crystal X-ray diffraction. DFT calculations show the formation of the complexes from (Cp?MCl₂)₂ and EPh₃ (E = P, As, Sb) to be highly exothermic, although the enthalpic driving force is decreasing in the expected sequence P > As > Sb.

Full text of DOI:10.1016/j.jorganchem.2015.09.006

Journal of Organometallic Chemistry 799-800 (2015) 70e74
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Rhodium(III) and iridium(III) half-sandwich complexes with tertiary
arsine and stibine ligands
Brian A. Chalmers, Michael Bühl, Phillip S. Nejman, Alexandra M.Z. Slawin,
J. Derek Woollins, Petr Kilian*
EaStChem School of Chemistry, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 3 July 2015
Received in revised form
31 August 2015
Accepted 2 September 2015
Available online 8 September 2015
The syntheses of rhodium(III) and iridium(III) half-sandwich complexes containing tertiary arsine and
stibine ligands of the form [Cp*M(L)Cl2] (M ¼ Rh, Ir; L ¼ AsEt3, AsPh3, SbPh3) are reported. These
compounds represent infrequent examples of rhodium and iridium metal complexes bearing arsenic or
antimony ligands. All new compounds were fully characterised using 1H and 13C NMR spectroscopy, mass
spectrometry and single crystal X-ray diffraction. DFT calculations show the formation of the complexes
from (Cp*MCl2)2 and EPh3 (E ¼ P, As, Sb) to be highly exothermic, although the enthalpic driving force is
decreasing in the expected sequence P > As > Sb.
Keywords:
Arsine
© 2015 Elsevier B.V. All rights reserved.
Stibine
Rhodium
Iridium
Half-sandwich complex
DFT calculations
1. Introduction
complex mere[(Ph3Sb)3RhCl3] (C) [7] (Fig. 1). Iridium containing
complexes with arsenic and antimony ligands are much rarer with
The dinuclear rhodium and iridium complexes [Cp*RhCl2]2 and
[Cp*IrCl2]2 are easily prepared by reacting RhCl3 or IrCl3 hydrates
with pentamethylcyclopentadiene (Cp*H) as first reported by
Maitlis [1]. The dimers are split to mononuclear complexes upon
quantitative reactions with triethylphosphine, resulting in
[Cp*Rh(PEt3)Cl2] and [Cp*Ir(PEt3)Cl2] as air stable solids [2]. The
crystal structures of these two compounds were recently deter-
mined within our research group [3]. In these triethylphosphine
complexes the chloride ligands can be displaced by a range of other
ligands such as selenide, telluride, azide and acetate, which makes
them rather versatile synthons [3,4]. In sharp contrast to phos-
phines, a search of the Cambridge Structural Database (CSD) for
Cp*RhCl2 and Cp*IrCl2 fragments coordinated to arsine or stibine
ligands resulted in zero hits.
only a few known, including trans-[IrHCl(
h
3-C3H5)(SbiPr3)2] (D)
and trans-[IrHCl(
h
3-C8H13)(SbiPr3)2] (E) [8]. Kemmitt reacted
RhCl3∙xH2O, RhCl2(C2H4)4 and Rh2(CO)4Cl2 precursors with a se-
ries of rather electron poor pnictine ligands (C6F5)3E, (C6F5)2PhE
and (C6F5)Ph2E (E ¼ P, As, Sb) [9]. While all the phosphines formed
expected complexes, of arsine ligands only (C6F5)Ph2As and
Rh2(CO)4Cl2 gave the expected complex [(C6F5)Ph2As]2Rh(CO)Cl
(F), while no reaction was observed for all other arsine ligands. No
reaction took place between any of the stibine ligands and
rhodium precursor complexes. Kemmitt also used K2PtCl4 and
PtX2 (X ¼ Cl, Br, I) as reactants in this study. These gave similar
results with no stibine complexes being formed, although (C6F5)
Ph2As did form the expected Pt complexes [9]. The arsine and
stibine complexes cis-[PtCl2(AsEt3)] and cis-[PtCl2(AsMe2Ph)2] are
also known although it is still evident that phosphine complexes
of transition metals are far more prevalent than As and Sb com-
plexes [10,11].
A few rhodium complexes with arsine and stibine ligands are
known such as the Rh(I) chelate complex [(Ph2AsCH2AsPh2)
Rh(CO)Cl]2 (A) [5], trans-[(Ph3Sb)2Rh(CO)Cl] (B) [6] and a Rh(III)
In this paper we report the synthesis of six novel mononuclear
complexes, 1aec and 2aec, of the form [Cp*M(ER3)Cl2] (M ¼ Rh, Ir;
E ¼ As, Sb, R ¼ Et, Ph). These complexes are potential synthons as
the chloride ligands are likely to be easily displaced by a range of
* Corresponding author.
E-mail address: pk7@st-andrews.ac.uk (P. Kilian).
http://dx.doi.org/10.1016/j.jorganchem.2015.09.006
0022-328X/© 2015 Elsevier B.V. All rights reserved.

B.A. Chalmers et al. / Journal of Organometallic Chemistry 799-800 (2015) 70e74
71
Fig. 1. Examples of rhodium and iridium complexes with arsine and stibine ligands.
other ligands (as discussed for the related triethylphosphine com-
plexes above). The complexes are easily prepared in excellent yields
and good purity and are thermally stable (m.p. >190 ꢀC), in
particular no signs of pnictine ligands elimination were observed at
room or elevated temperatures. In addition, the complexes are fully
air and moisture stable.
room temperature gave the expected mononuclear pnictine com-
plexes 1b [Cp*Rh(AsPh3)Cl2], 1c [Cp*Rh(SbPh3)Cl2], 2b [Cp*Ir(-
AsPh3)Cl2], and 2c [Cp*Ir(SbPh3)Cl2] in excellent yields (93e99%)
(Scheme 1). Similarly to compounds 1a and 2a, the ortho hydrogens
of the phenyl group resonances in 1b, 1c, 2b and 2c show a
noticeable high frequency shift of around 0.2 ppm in the 1H NMR
spectra compared to those in uncoordinated AsPh3 and SbPh3. The
homogeneity of 1aec and 2aec was confirmed by microanalysis
and high-resolution mass spectrometry.
2. Results & discussion
2.1. Synthesis and NMR
2.2. Structural analysis
The addition of two molar equivalents of triethylarsine to a
dichloromethane solution of [Cp*MCl2]2 (M ¼ Rh, Ir) at room
temperature and subsequent removal of the volatiles after two
hours of stirring resulted in the desired mononuclear complexes 1a
[Cp*Rh(AsEt3)Cl2] and 2a [Cp*Ir(AsEt3)Cl2] in near quantitative
yields (>98%) (Scheme 1).
Crystal structures of all new complexes were determined; these
are shown in Fig. 2 and in Table 1. Crystals for X-ray diffraction
work were grown from either acetone, dichloromethane or 1,2-
dichloroethane at room temperature. Compounds 1a, 1c, 2ae2c
have two or three independent molecules in the asymmetric units
all of which have very similar geometries. Values presented in the
discussion of these molecules are the mean values. Data for 2a is
of somewhat lower quality, but is sufficient to demonstrate the
connectivity of the molecule; the bond lengths and angles are in
line with those observed in the other molecules. All of the com-
plexes (1aec and 2aec) are isostructural and attain piano stool
geometry (around the metal centre) with the h5eCp* ring slightly
tilted, as shown by the slight variation in the MꢁC bond lengths
(see Table 1 and Fig. 2). The MeE and MꢁC (M ¼ Ir, Rh; E ¼ As, Sb)
bonds are all as expected [12]. The pnictogen ligands adopt
tetrahedral geometry, again, with normal AseC and SbeC bond
lengths and angles.
In the 1H NMR spectra of 1a and 2a, a noticeable shift towards
higher frequency is seen for CH2 as well as CH3 groups of the ethyl
substituents, consistent with transfer of the electron density from
the arsenic atom upon coordination to the metal centre [1a: dH 2.04
(q) and 1.23 (t); 2a: dH 2.05 (q) and 1.21 (t); cf. AsEt3: dH 1.26 (q) and
1.06 (t), see Figure S1 in Supporting Information]. The methyl
groups of the Cp* ligands in [Cp*M(AsEt3)Cl2] (1a and 2a) also show
a slight high frequency shift (ca. 0.1 ppm) cf. the precursor
[Cp*MCl2]2 complexes.
The reactions of EPh3 (E ¼ As, Sb) with [Cp*MCl2]2 (M ¼ Rh, Ir) at
Comparing the AsPh3 and SbPh3 complexes (1b vs. 1c and 2b vs.
2c) the difference in RheE and IreE (E ¼ As, Sb) bond lengths is up
to 6%; this is somehow smaller than expected from the differences
in covalent radii (rcov As 1.19 Å; Sb 1.39 Å, 14% difference) [13]. The
MꢁCl bonds in all compounds fall within the expected range of
other half-sandwich complexes.
2.3. Computational analysis
To complement the experimental findings, we performed den-
sity functional theory (DFT) calculations at an appropriate level,
BP86-D3. Computed metal-pnictogen distances, Wiberg Bond
Indices (WBIs) [14] as well as enthalpies and free energies for the
Scheme 1. Syntheses reported in this paper.

72
B.A. Chalmers et al. / Journal of Organometallic Chemistry 799-800 (2015) 70e74
Fig. 2. Ellipsoid plots of the crystal structures of 1a¡1c and 2a¡2c Hydrogen atoms, solvating molecules (for 1b) and other molecules in the asymmetric unit are omitted. Ellipsoids
are drawn at the 40% level.
Table 1
formation reaction according to Eq. (1) are collected in Table 2.
Selected bond lengths (Å) and angles (ꢀ) 1aec and 2aec. Compounds with multiple
molecules in the asymmetric unit have their values reported as ranges.
Â
Ã
1
2
Cp*MCl2 þEPh3 /Cp*MðEPh3ÞCl2 ðM¼Rh; Ir;E¼P;As;SbÞ
2
1a
1b$CH2Cl2
1c
Eq.1
RheE
RheCl
RheC
2.425(1)e2.4372(9) 2.444(1)
2.5703(7)/2.5733(8)
2.397(1)e2.424(2)
2.145(5)e2.200(6)
91.81(5)/90.64(5)
84.27(4)e86.01(4)
2c
2.394(2)e2.428(2)
2.13(1)e2.214(7)
2.397(3)/2.418(3)
2.16(1)e2.22(1)
91.2(1)
All reactions according to Eq. (1) are computed to be highly
exothermic, with the absolute enthalpic driving forces decreasing
in the expected sequence P > As > Sb for either metal (see
CleRheCl 92.10(6)e97.22(6)
EeRheCl
D
H
85.43(5)e88.07(6)
2a
85.62(8)/90.35(8)
2b
values in Table 2). Notably, the driving force for SbPh3 coordination
still accounts to 67% (Rh) and 66% (Ir) of that for PPh3 [17]. This
sequence is not reflected in the MeE WBIs, which are not very
sensitive toward the nature of pnictogen E, adopting values around
ca. 0.7 and 0.8 for M ¼ Rh and Ir, respectively. Both computed WBIs
and driving forces agree that the bonds involving iridium are
slightly stronger than those involving rhodium (by ca. 12e22 kJ
IreE
IreCl
IreC
CleIreCl
EeIreCl
2.381(4)/2.384(3)
2.383(6)e2.42(1)
2.10(3)e2.21(4)
87.6(3)/88.6(3)
86.4(2)e89.2(2)
2.4269(7)/2.4333(7) 2.5742(8)/2.5761(7)
2.408(1)e2.413(1)
2.156(4)e2.211(4)
89.05(3)/90.06(3)
86.49(3)e87.30(3)
2.407(1)e2.426(1)
2.153(4)e2.217(4)
87.90(4)/89.04(4)
84.76(3)e86.16(3)
mole1 in terms of
DH).
Table 2
3. Conclusions
Metal-pnictogen (MeE) bond distances (in Å) observed in the crystal and calculated
at the BP86-D3 level (SDD/6-31G* basis). Wiberg Bond Indices obtained at the same
level are given in square brackets. Calculated reaction enthalpies and free energies
(in kJ molꢁ1) according to Eq. (1).
A series of novel Rh(III) and Ir(III) h5eCp* half-sandwich com-
plexes with arsine and stibine ligands have been prepared and fully
characterised by 1H and 13C NMR spectroscopy, elemental micro-
analysis and high resolution mass spectrometry. All of the six novel
compounds were structurally characterised and shown to display
only small deviations in the MeE bond lengths and overall geom-
etries. Complementary DFT calculations indicated the expected
trend, in that the more Lewis basic pnictogens have a higher for-
mation enthalpy, although MeE bond WBIs remain essentially
constant within each metal series. Synthetic applications of here
reported complexes, such as in the formation of multimetallic
systems, and chloride ligand metathesis will be investigated next.
Compd. (M/E)
dMeE (X-ray)a
dMeE (calc) [WBI]
D
H
DG
(Rh/P)b
1b (Rh/As)
1c (Rh/Sb)
(Ir/P)c
2b (Ir/As)
2c (Ir/Sb)
2.341
2.444
2.573/2.570
2.318
2.433/2.427
2.574/2.576
2.295 [0.68]
2.394 [0.68]
2.539 [0.71]
2.296 [0.78]
2.404 [0.76]
2.561 [0.78]
ꢁ116.3
ꢁ95.3
ꢁ75.0
ꢁ51.0
ꢁ53.5
ꢁ98.4
ꢁ66.3
ꢁ59.0
ꢁ78.0
ꢁ138.2
ꢁ110.2
ꢁ90.9
a
This work (except where otherwise noted); values are given for all independent
molecules in the asymmetric unit (one or two).
b
CSD ref. code AKOVEC [15].
CSD ref. code VOGZOH [16].
c

B.A. Chalmers et al. / Journal of Organometallic Chemistry 799-800 (2015) 70e74
73
4. Experimental section
Dichloromethane (20 mL) was added, and the solution was left to
stir for 2 h at ambient temperature. The volatiles were removed in
vacuo to give a red powder (534 mg, 93%) (Mp. 251 ꢀC with
decomposition). Crystals suitable for X-ray diffraction were grown
from dichloromethane at room temperature. Elemental Analysis:
Calcd. (%) for C28H30Cl2AsRh (615.27 g mole1): C 54.66, H 4.91.
Found: C 54.76, H 4.86. 1H NMR: dH (500.1 MHz, CD2Cl2) 7.81e7.75
(6H, m, oePh), 7.50e7.37 (9H, m, mePh, pePh), 1.45 (15H, s,
5 ꢂ CH3, Cp*). 13C{1H} NMR: dC (125.8 MHz, CD2Cl2) 134.1 (s, oePh),
133.8 (s, Cipso), 130.0 (s, pePh), 128.5 (s, mePh), 97.5 (s, Cipso, Cp*),
4.1. General considerations
Synthetic manipulations for compounds 1a and 2a were per-
formed under an atmosphere of nitrogen using standard Schlenk-
line techniques. Dry solvents were collected from an MBraun Sol-
vent Purification System and stored over molecular sieves. Chem-
icals were purchased from Sigma Aldrich, Alfa Aesar, Precious
Metals Online or were taken from the laboratory inventory and
used without further purification. The two precursor metal com-
plexes [Cp*MCl2]2 (M ¼ Rh, Ir) were prepared in good yields via the
reaction of the chlorides MCl3$3H2O with Cp*H [1]. Triethylarsine
was prepared via the reaction of excess ethylmagnesium bromide
with arsenic trichloride [18], which in turn was prepared by the
reaction of As2O3 with SOCl2 [19]. All NMR spectra were recorded
using a Bruker Avance 500 or Bruker Avance III 500 spectrometer at
25 ꢀC. 13C NMR spectra were recorded using the DEPT-Qe135 pulse
sequence with broadband proton decoupling. In 1H and 13C NMR,
tetramethylsilane was used as a reference. Residual solvent peaks
were also used for calibration (CD2Cl2 dH 5.36, dC 53.5 ppm).
8.7 (s, 5 ꢂ CH3, Cp*). Infrared: (KBr disc, cmꢁ1
)
n
¼ 3049 m (nAreH),
2959 m (nCeH), 1489s, 1437s, 1078s, 1025s, 740vs, 659vs, 477s.
Raman: (glass capillary, cmꢁ1
)
n
¼ 3055s, 2914s, 1003vs, 415s.
HRMS (ESþ): m/z: Calcd. (%) for C28H30AsClRh: 579.0307, found
579.0290 (100) [MꢁCl]; Calcd. for C12H18NClRh: 314.0183 (95)
[MeCleAsPh3 þ MeCN], found 314.0170; Calcd. for C10H15ClRh:
272.9917, found 272.9906 (25) [MeCleAsPh3].
[Cp*Rh(SbPh3)Cl2] (1c): This was prepared as per compound 1b
using [Cp*RhCl2]2 (150 mg, 242
mmol) and SbPh3 (171 mg,
485
m
mol) giving 1c as a red solid (317 mg, 99%) (Mp. 235 ꢀC with
decomposition). Crystals suitable from X-ray diffraction were
grown from slow diffusion of hexane into a saturated solution of 1c
in dichloromethane. Elemental Analysis: Calcd. (%) for
Chemical shifts (d) are given in parts per million (ppm) and
coupling constants (J) are given in Hertz (Hz). Infrared spectra were
recorded as KBr discs (range 4000e200 cmꢁ1); Raman spectra were
recorded on solid samples in glass capillaries using a dipole pum-
ped NdYAG excitation laser (range 3500e150 cmꢁ1), both using a
PerkineElmer System 2000 NIR/Raman FT Spectrometer. Melting
points were determined in sealed glass capillaries using a Stuart
SMP 30 melting point apparatus. Mass Spectrometry was carried
out at either the University of St Andrews Mass Spectrometry Ser-
vice by Mrs Caroline Horsburgh or at the EPSRC UK National Mass
Spectrometry Facility in Swansea. Elemental microanalysis was
performed by Mr Stephen Boyer at London Metropolitan University.
C
28H30Cl2SbRh (662.11 g mole1): C 50.79, H 4.57. Found: C 50.66, H
4.59. 1H NMR: dH (500.1 MHz, CD2Cl2) 7.78e7.75 (6H, m, oePh),
7.49e7.42 (9H, m, mePh, pePh), 1.61 (15H, s, 5 ꢂ CH3, Cp*). 13C{1H}
NMR: dC (125.8 MHz, CD2Cl2) 136.2 (s, oePh),131.2 (s, Cipso),130.2 (s,
1
pePh), 129.0 (s, mePh), 97.1 (d JCRh ¼ 7.6 Hz, Cipso, Cp*), 9.1 (s,
5 ꢂ CH3, Cp*). Infrared: (KBr disc, cmꢁ1
)
n
¼ 3047 m (nAreH),
2957 m (nCeH), 1432s, 1022s, 743s, 733vs, 694s, 453s. Raman: (glass
capillary, cmꢁ1
)
n
¼ 3056s (nAreH), 2915s (nCeH), 1001vs, 658s, 421s.
HRMS (ESþ): m/z (%) Calcd. for C28H30ClSbRh: 625.0129, found
625.0105 (100) [MꢁCl].
[Cp*Ir(AsEt3)Cl2] (2a): This was prepared as per compound 1a
4.2. DFT calculations
using [Cp*IrCl2]2 (200 mg, 250
mmol) and AsEt3 (81 mg, 170 mL,
500
m
mol) giving 2a as an orange solid (275 mg, 98%) (Mp. 194 ꢀC
Geometries were fully optimized at the BP86-D3/6-31G* level
[20,21]; Rh, Ir and Sb were described with relativistically adjusted
effective core potentials from the StuttgarteDresden groups
(denoted SDD) with the associated valence basis sets [22] (the Sb
basis was augmented with a set of d-polarization functions), As was
described with the 962(d) all-electron Binning-Curtiss basis. See
Supporting Information for further details and references.
with decomposition). Crystals suitable for X-ray diffraction were
grown from acetone at ambient temperature. Elemental Analysis:
Calcd. (%) for C16H30Cl2AsIr (560.45 g molꢁ1): C 34.29, H 5.39.
Found: C 34.18, H 5.38. 1H NMR: dH (500.1 MHz, CD2Cl2) 2.05 (6H, q,
3JHH ¼ 7.8 Hz, CH2), 1.70 (15H, s, 5 ꢂ CH3, Cp*), 1.21 (9H, t,
3JHH ¼ 7.8 Hz, CH3) 13C{1H} NMR: dC (125.8 MHz, CD2Cl2) 89.1 (s,
C
ipso, Cp*), 13.4 (s, CH2), 8.9 (s, CH3, Cp*), 8.6 (s, CH3). Infrared: (KBr
¼ 2930s (nCeH), 1452s, 1376s, 1031vs, 733s. Raman:
(glass capillary, cmꢁ1
¼ 2918s (nAr-H), 591s, 561s, 412s, 288s.
disc, cmꢁ1
) n
4.3. Synthetic methods
) n
HRMS (ACPIþ): m/z (%) Calcd. for C26H45Cl3AsIr2: 923.1062, found
923.1029 (10) [2MeCleAsEt3]; Calcd. for C16H31Cl2AsIr: 560.0648,
found 561.0631 (20) [MþH]; Calcd. for C16H30ClAsIr: 525.0868,
found 525.0862 (70) [MꢁCl]; Calcd. for C6H16As: 163.0468, found
163.0459 (100) [Et3As þ H].
[Cp*Rh(AsEt3)Cl2] (1a): Under an atmosphere of dry nitrogen, a
solution of [Cp*RhCl2]2 (300 mg, 485
(10 mL) was prepared. To this a solution of AsEt3 (160 mg, 0.14 mL,
970 mol) in dichloromethane (10 mL) was added in one portion.
mmol) in dichloromethane
m
After stirring for two hours at ambient temperature, the volatiles
were removed in vacuo to give an air-stable red powder (452 mg,
99%) (Mp. 200 ꢀC with decomposition). Crystals suitable for X-ray
diffraction were grown from acetone at ambient temperature.
Elemental Analysis: Calcd. (%) for C16H30Cl2AsRh (471.14 g mole1): C
40.79, H 6.41. Found: C 40.75, H 6.42. 1H NMR: dH (500.1 MHz,
CD2Cl2) 2.04 (6H, q, 3JHH ¼ 7.8 Hz, CH2), 1.69 (15H, s, 5 ꢂ CH3, Cp*),
1.23 (9H, t, 3JHH ¼ 7.8 Hz, CH3). 13C{1H} NMR: dC (125.8 MHz, CD2Cl2)
96.5 (d, 1JCRh ¼ 7.3 Hz, qC), 14.6 (s, CH2), 9.2 (s, 5 ꢂ CH3, Cp*), 9.0 (s,
[Cp*Ir(AsPh3)Cl2] (2b): This was prepared as per compound 1b
using [Cp*IrCl2]2 (200 mg, 250 mmol) and AsPh3 (154 mg, 500 mmol)
giving 2b as an orange solid (351 mg, 99%) (Mp. 283 ꢀC with
decomposition). Crystals suitable for X-ray diffraction were grown
from 1,2-dichloroethane at ambient temperature. Elemental
Analysis: Calcd. (%) for C28H30Cl2AsIr (704.58 g mole1): C 47.73, H
4.29. Found: C 47.83, H 4.20. 1H NMR: dH (500.1 MHz, CD2Cl2)
7.77e7.74 (6H, m, oePh), 7.48e7.41 (9H, m, mePh, pePh),1.45 (15H,
s, 5 ꢂ CH3, Cp*). 13C{1H} NMR: dC (125.8 MHz, CD2Cl2) 134.1 (s,
CH3). Infrared: (KBr disc, cmꢁ1
)
n
¼ 2958s (nCeH), 2871s, 1450s,
oePh), 133.2 (s, Cipso), 130.1 (s, pePh), 128.4 (s, mePh), 90.3 (s, Cipso,
1374s,1027vs,744s, 582s. Raman:(glasscapillary, cmꢁ1
)
n
¼ 2959m,
Cp*), 8.3 (s, 5 ꢂ CH3, Cp*). Infrared: (KBr disc, cmꢁ1
)
n
¼ 3054 m
2920s (nAr-H), 617s, 589s, 551s, 413vs, 282s. HRMS (ESþ): m/z (%)
Calcd. for C16H30ClAsRh: 435.0307, found 435.0298 [MꢁCl].
(nAreH), 2987 m (nCeH), 1484s, 1436vs, 1078s, 1027s, 741vs, 695vs,
483s. Raman: (glass capillary, cmꢁ1
1582s, 1003vs, 416s, 291s. HRMS (APCIþ): m/z (%) Calcd. for
C
28H30Cl2AsIr: 704.0551, found 704.0551 (45) [Mþ]; Calcd. for
)
n
¼ 3056s, 2918 m (nAr-H),
[Cp*Rh(AsPh3)Cl2] (1b): Solid [Cp*RhCl2]2 (295 mg, 477
was added to a flask containing solid AsPh3 (300 mg, 978
m
mol)
mmol).

74
B.A. Chalmers et al. / Journal of Organometallic Chemistry 799-800 (2015) 70e74
F. Martínez, Organometallics 17 (1998) 4578e4596.
[3] P.S. Nejman, B. Morton-Fernandez, N. Black, D.B. Cordes, A.M.Z. Slawin,
P. Kilian, J.D. Woollins, J. Organomet. Chem. 776 (2015) 7e16.
[4] (a) P. Portius, A.J.H.M. Meijer, M. Towrie, B.F. Crozier, I. Schiager, Dalton Trans.
43 (2014) 17694e17702;
C28H30ClAsIr: 669.0881, found 669.0860 (20) [MꢁCl]; Calcd. for
C
18H16As: 307.0468, found 307.0459 (100) [Ph3As þ H].
[Cp*Ir(SbPh3)Cl2] (2c): This was prepared as per compound 1b
using [Cp*IrCl2]2 (150 mg, 188 mmol) and SbPh3 (133 mg, 376 mmol)
(b) D.A. Freedman, K.R. Mann, Inorg. Chem. 30 (1991) 836e840;
(c) M. Herberhold, T. Daniel, D. Daschner, W. Milius, B. Wrackmeyer,
J. Organomet. Chem. 585 (1999) 234e240;
(d) L. Andreucci, P. Diversi, G. Ingrosso, A. Lucherini, F. Marchetti, V. Adovasio,
M. Nardelli, J. Chem. Soc. Dalton Trans. (1986) 477e487;
(e) R. Bertani, P. Diversi, G. Ingrosso, A. Lucherini, F. Marchetti, V. Adovasio,
M. Nardelli, S. Pucci, J. Chem. Soc. Dalton Trans. (1988) 2983e2994;
(f) W. Rigby, P.M. Bailey, J.A. McCleverty, P.M. Maitlis, J. Chem. Soc. Dalton
Trans. (1979) 371e381;
giving 2c as an orange solid (280 mg, 99%) (Mp. 213 ꢀC with
decomposition). Crystals suitable for X-ray diffraction were grown
from dichloromethane at ambient temperature. Elemental Anal-
ysis: Calcd. (%) for C28H30Cl2SbIr (751.42 g mole1): C 44.76, H 4.02.
Found: C 44.64, H 4.02. 1H NMR: dH (500.1 MHz, CD2Cl2) 7.77e7.74
(6H, m, oePh), 7.51e7.42 (9H, m, oePh, pePh), 1.61 (15H, s, 5 ꢂ CH3,
Cp*). 13C{1H} NMR: dC (125.8 MHz, CD2Cl2) 136.2 (s, oePh), 130.2 (s,
pePh), 129.8 (s, Cipso), 129.0 (s, mePh), 89.9 (s, Cipso, Cp*), 8.7 (s, 5 ꢂ
(g) M. Herberhold, G.-X. Jin, A.L. Rheingold, Z. Anorg. Allg. Chem. 631 (2005)
135e140.
CH3, Cp*). Infrared: (KBr disc, cmꢁ1
(
)
n
¼ 3048 m (nAreH), 2960 m
[5] (a) M. Cowie, S.K. Dwight, Inorg. Chem. 20 (1981) 1534e1538;
(b) J.T. Mague, Inorg. Chem. 8 (1969) 1975e1981.
[6] S. Otto, A. Roodt, Inorg. Chim. Acta 331 (2002) 199e207.
[7] R. Cini, G. Tamasi, S. Defazio, M. Corsini, F. Berrettini, A. Cavaglioni, Polyhedron
25 (2006) 834e842.
nCeH), 1432s, 733vs, 694vs, 462s. Raman: (glass capillary, cmꢁ1
)
n
¼ 3048s (nAreH), 2920s (nCeH), 1001vs, 659s, 419s. HRMS (ESþ):
m/z (%) Calcd. for C28H20ClSbIr: 715.0704, found 715.0669 (100)
[MꢁCl].
[8] D.A. Ortmann, O. Gevert, M. Laubender, H. Werner, Organometallics 20 (2001)
1776e1782.
[9] R.D.W. Kemmitt, D.I. Nichols, R.D. Peacock, J. Chem. Soc. A (1968) 2149e2152.
[10] As an example, a search of the CSD for RheE fragments (E ¼ P, As, Sb)
returned 43 hits for E ¼ Sb, 67 hits for E ¼ As and 5,450 hits for E ¼ P.
[11] (a) S. Otto, A.J. Muller, Acta Crystallogr. Sect. C Cryst. Struct. Commun. 57
(2001) 1405e1407;
5. X-ray diffraction and computational details
The crystallographic and computational details relating to this
work can be found in the supporting information available as a free
download. CCDC 1410325-1410330 contain the supplementary
crystallographic data for this paper. These data can be obtained free
of charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
(b) S. Otto, M.H. Johansson, Inorg. Chim. Acta 329 (2002) 135e140;
(c) P.P. Phadnis, V.K. Jain, A. Klein, M. Weber, W. Kaim, Inorg. Chim. Acta 346
(2003) 119e128;
(d) O.F. Wendt, A. Scodinu, L.I. Elding, Inorg. Chim. Acta 277 (1998) 237e241.
[12] A search of the CSD for RheAs bonds gave a mean value of 2.443 Å (67 hits);
IreAs bonds gave a mean value of 2.44 Å (29 hits); RheSb bonds gave a mean
value of 2.59 Å (43 hits) and IreSb bonds gave a mean of 2.61 Å (8 hits).
[13] B. Cordero, V. Gomez, A.E. Platero-Prats, M. Reves, J. Echeverria, E. Cremades,
F. Barragan, S. Alvarez, Dalton Trans. (2008) 2832e2838.
[14] K.B. Wiberg, The WBI is a measure for the covalent character of a bond and
Notes
adopts values close to
1083e1096.
[15] B.A. Paz-Michel, F.J. Gonzalez-Bravo, L.S. Hernandez-Munoz, M.A. Paz-San-
doval, Organometallics 29 (2010) 3709e3721.
1 for true single bonds, Tetrahedron 24 (1968)
The author declares no competing financial interest.
ꢀ
ꢀ
~
Acknowledgements
[16] B. Paz-Michel, M. Cervantes-Vazquez, M.A. Paz-Sandoval, Inorg. Chim. Acta
361 (2008) 3094e3102.
[17] Driving forces are slightly smaller for AsEt3 than for AsPh3, cf. results for 1a in
the Supporting Information.
[18] W.A. Herrmann, H.H. Karsch, Synthetic Methods of Organometallic and
Inorganic Chemistry Vol 3: Phosphorus, Arsenic, Antimony and Bismuth, vol.
3, Thieme, New York, 1996.
[19] K.S. Pandey, A. Steiner, W.H. Roesky, S. Kamepalli, A.H. Cowley, Inorg. Synth.
31 (1997) 148e150.
This work was financially supported by the EPSRC (EP/J500549/1
and EP/L505079/1) and the EPSRC National Mass Spectrometry
Service Centre (NMSSC) Swansea.
Appendix A. Supplementary data
[20] S. Grimme, J. Antony, S. Ehrlich, H. Krieg, Empirical three-body dispersion
correction from, J. Chem. Phys. 132 (2010) 154104.
[21] (a) A.D. Becke, Phys. Rev. A 38 (1988) 3098e3100;
(b) J.P. Perdew, Phys. Rev. B 33 (1986) 8822e8824;
(c) J.P. Perdew, Phys. Rev. B 34 (1986) 7406.
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2015.09.006.
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