The influence of phosphine cone angle on the synthesis and structures of [Rh(PR3)(Binor-S)]+ complexes that show C-C sigma interactions

Article abstract of DOI:10.1016/j.jorganchem.2012.09.013

Complexes that show C-C···Rh sigma interactions have been synthesized and characterised by NMR spectroscopy and X-ray diffraction: [Rh(PR₃)(Binor-S)][BAr^F₄], R = P ^tBu₂Me, PCy₂Ph; Ar = C₆H ₃(CF₃)₂, Binor-S = 1,2,4,5,6,8-dimetheno-S- indacene. These studies, in concert with previously published work, show that there is a rather narrow window of phosphine steric profile that supports the isolation of these interesting complexes, with the phosphine cone angle lying between 160° and 170°.

Full text of DOI:10.1016/j.jorganchem.2012.09.013

Journal of Organometallic Chemistry 730 (2013) 90e94
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
The influence of phosphine cone angle on the synthesis and structures of
[Rh(PR3)(BinoreS)]þ complexes that show CeC sigma interactions
1
*
Adrian B. Chaplin , Andrew S. Weller
Department of Chemistry, University of Oxford, Chemistry Research Laboratories, Mansfield Road, Oxford OX1 4TA, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
Complexes that show CeC$$$Rh sigma interactions have been synthesized and characterised by NMR
spectroscopy and Xeray diffraction: [Rh(PR3)(BinoreS)][BArF4], R ¼ PtBu2Me, PCy2Ph; Ar ¼ C6H3(CF3)2,
BinoreS ¼ 1,2,4,5,6,8-dimetheno-S-indacene. These studies, in concert with previously published work,
show that there is a rather narrow window of phosphine steric profile that supports the isolation of these
interesting complexes, with the phosphine cone angle lying between 160ꢀ and 170ꢀ.
Ó 2012 Elsevier B.V. All rights reserved.
Received 25 August 2012
Received in revised form
18 September 2012
Accepted 20 September 2012
Keywords:
Sigma complex
Agostic
Rhodium
CeC activation
1. Introduction
derived ligand to the metal centre that results in an M$$$CeC
sigma interaction, while the other cyclopropyl group has under-
The synthesis, structures and reactivity of transition metal
complexes in which a saturated single bond interacts with the
metal centre via a 3-centre 2-electron bond, the so called sigma-
complexes [1], are now well established. Examples include: CeH
intramolecular agostic interactions, CeH$$$M [2]; dihydrogen
complexes, H2$$$M [1]; sigma boranes, R3NBH3$$$M [3]; and
silanes, R3SieH$$$M. [4]. Intermolecular sigma-alkane complexes
of transition metals are also known, but are generally difficult to
isolate in solution due to the facile loss of alkane [5e7]. Compared
to those with CeH agostic interactions, complexes in which a CeC
saturated bond forms a sigma-complex with a transition metal are
rarer: a consequence of the relative inaccessibility and orbital
directionality of a CeC bond [8]. Despite this there are a growing
number of examples reported [8e21], some of which are of direct
relevance to CeC activation processes [8,22]. Related SieSi$$$M
interactions have also been reported [23,24]
gone CeC activation to form a metallacyclobutane (Scheme 1) [25e
29]. These complexes also have a weak supporting CeH$$$M
agostic interaction from the alkyl phosphine. In solution (Rh and
Ir) and the solid-state (Ir) these complexes undergo reversible CeC
activation of the BinoreS fragement. For Rh we have also shown
that they undergo reductive elimination of BinoreS readily on
addition of exogenous Lewis base, and thus serve as a useful source
of the reactive 10-electron {Rh(PR3)}þ fragment [25,30e32]
The synthetic methodology used for the synthesis of these
complexes is one in which a [M(PR3)(NBD)2]þ cation, usually
ꢁ
partnered with the [BArF
]
counterion, {NBD ¼ norbornadiene;
4
ArF ¼ 3,5-C6H3(CF3)2; M ¼ Rh, R ¼ Cy, iPr, Cyp (Cyp ¼ cyclopentyl)
[25,26]; M ¼ Ir, R ¼ iPr [27]} undergoes a cyclodimerization of the
two bound-dienes to give the BinoreS fragment directly on the
metal centre [33]. [M(PR3)(NBD)2]þ can be generated by reaction of
an alkyl phosphine (e.g. PiPr3 or PCy3) with [Rh(NBD)2]þ or by
addition of NBD/Na[BArF4] to [RhCl(PR3)(NBD)] or [IrCl(PiPr3)(COE)]
(COE ¼ cyclooctene) [26,27]. In the case of Rh the intermediates
[Rh(PR3)(NBD)2]þ cannot be isolated, or even observed, as forma-
tion of the BinoreS complex is fast. However for Iridium this
intermediate can be isolated, i.e. [Ir(PiPr3)(NBD)2][BArF4], a conse-
quence of the stronger IreC bonds. In all cases it is the addition of
the phosphine that induces the dimerization of NBD. This reaction
is also catalytic, using the [Rh(NBD)2]þ/PR3 system [34], and we
have shown that [M(PR3)(BinoreS)]þ are intermediates in this
process [25]
Over the fast few years we have reported on the synthesis of
[M(PR3)(BinoreS)]þ cations (BinoreS ¼ 1,2,4,5,6,8-dimetheno-S-
i
indacene; R ¼ Cy, Pr, cyclopentyl; M ¼ Rh, Ir) in which there is
a close approach of one cyclopropyl fragment in the BinoreS
* Corresponding author.
E-mail address: andrew.weller@chem.ox.ac.uk (A.S. Weller).
Present address: Department of Chemistry, University of Warwick, CV34 7AL,
1
UK.
0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2012.09.013

A.B. Chaplin, A.S. Weller / Journal of Organometallic Chemistry 730 (2013) 90e94
91
C3) and CeC$$$Rh sigma interaction (Rh/C8/C10). The metal-
lacyclobutane shows RheC distances as expected for 2ecentree2
ꢀ
electron interactions (e.g. Rh1eC1 ¼ 2.029(3) A in 2), while the
CeC$$$Rh sigma interaction is longer as expected (e.g. RheC8
ꢀ
2.370(4) A in 2). The CeC bond C8-C10 is also lengthened
compared to a closeeanalogue of free BINOReS, consistent with the
ꢀ
formation of the sigma interaction [cf. C8eC10 1.616(5) A 2, the
ꢀ
dioneederivative of BinoreS, 1.49(3) A] [37]. Although there might
appear to be
g CeH and b
CeH agostic interactions from the tBu and
Me groups in 1 and similar interactions from the cyclohexyl and
phenyl groups in 2, the RheC distances are all long for such inter-
Scheme 1. Generic Routes to [M(PR3)(BinoreS)]þ complexes.
ꢀ
ꢀ
actions (e.g. Rh1eC17 3.244(6) A, 1; Rh1eC32 3.307(4) A, 2) [38].
While computational and experimental charge density studies on
the Cy analogue to 1 and 2, [Rh(PCy3)(BinoreS)]þ [28], support the
presence of a weak agostic interaction with a comparably shorter
In this contribution we explore the synthesis of [Rh(PR3)(Binore
S)][BArF4] complexes using a number of different phosphines in
which the sterics (i.e. cone angle [35,36]) are varied while the
electronic contribution remains similar [35]. We find that, within
the sample of phosphines used, there is a rather narrow window for
the production of the CeC$$$Rh sigma complexes, being supported
by phosphines with cones-angles 160ꢀ to 170ꢀ.
ꢀ
RheC distance of 3.018(2) A, these data for 1 and 2 suggest that any
CeH$$$Rh interactions present are even weaker than this, at best.
These weak agostic interactions are fully consistent with the strong
trans-influence RheC bonds that lie opposite [39]. The overall
structural motif (Rh(III), two weak agostic CeH bonds trans to RheC
bonds) is similar to that reported for transe[Rh(2,20e
biphenyl)(PiPr3)2][BArF4] [40]. The CeH agostic interaction aside,
the structural metrics for the BinoreS fragment are very close to
2. Results and discussion
Taking a range of phosphines with different cone angles ranging
from PiBu3 (cone angle 143ꢀ) to PtBu3 (182ꢀ) the precursor
complexes [RhCl(NBD)(PR3)] where prepared. These were charac-
terised by NMR spectroscopy and elemental analysis and their data
are unremarkable showing all to be Rh(I) species in solution.
Addition of Na[BArF4], as a halide abstracting reagent, in C6H5F
solvent in the presence of NBD was used to generate the desired
BinoreS complexes. For some phosphines this resulted in intrac-
table mixtures of products. However, for PtBu2Me and PCy2Ph the
clean formation of the BinoreS complexes were observed,
[Rh(PR3)(BinoreS)][BArF4] (R ¼ PtBu2Me,1; PCy2Ph, 2), which could
be isolated in good yields, 66% and 89% respectively, as crystalline
materials, Scheme 2.
These results show that there is a range in the steric profile of
the phosphine that supports the isolation of these CeC$$$M sigma
complexes, lying between 160ꢀ and 170ꢀ. Smaller or larger than this
and intractable mixtures were formed. The solid-state structures of
1 and 2 are shown in Figs. 1 and 2 respectively. For 1 there are two
independent molecules in the unit cell (Z0 ¼ 2), but the structural
metrics of the {Rh(BinoreS)}þ fragment are the same for both
i
those previously reported for Pr, Cy and Cyp analogues (Table 1
compares selected structural data), for which NMR data [25,26],
X-ray crystallography [25,26], experimental chargeedensity
measurements [28] and DFT calculations [25,28] all support the
CeC$$$Rh motif.
Solution NMR data for 1 and 2 are also consistent with the
previously reported BinoreS complexes of Rh and Ir. Time-
averaged C2v symmetry (rather than the pseudo Cs in the solid-
state) is observed in solution at room temperature, i.e. only 4
Binor-S environments are observed in the 13C{1H} NMR spectrum
[41], while in the 1H NMR spectrum only 5 environments are
observed in a 4:2:2:4:4 ratio. As previously outlined this fluxional
process occurs via CeC bond making in the metallacyclobutane and
CeC bond breaking in the CeC$$$Rh bond that make the two sides
of the Binor-S fragment equivalent. Calculations indicate that this
occurs via a Rh(V) intermediate [26], and for [Ir(PiPr3)(BinoreS)]
[BArF4] we have shown that such an intermediate can be formed
in the solid-state [27]. For both 1 and 2 rotation around the RheP
bond must also be occurring at room temperature to produce the
observed C2v symmetry. In the 13C{1H} NMR spectrum for 1 the
time-averaged carbon environment assigned to C1/3/8/10 is
observed as a broad doublet [J ¼ 12 Hz], as previously noted in
other systems [25,26]. Interestingly for 2 this signal is further
resolved as a doublet of doublets [J ¼ 13, 4 Hz] consistent with
coupling to both 103Rh and 31P, as reported for the iPr-analogue [26].
In 1 the other coupling is clearly too small to be resolved.
within 3s (Table 1), the two differing by subtle differences in the
relative orientation of the phosphine, essentially being an enan-
tiomeric pair in the solid-state which would not be retained in
solution (vide infra).
In the solid-state both 1 and 2 show the expected [25,26] overall
structure with a BinoreS derived fragment coordinated to a,
formally, Rh(III) centre through a metallacyclobutane (Rh/C1/C2/
Scheme 2. Synthesis of compounds 1 and 2: dependence on the phosphine cone angle. (a)See reference [26]. (b) For cone angle calculations see references [35] and [36]. Generic
NMR and X-ray labelling scheme shown for 1.

92
A.B. Chaplin, A.S. Weller / Journal of Organometallic Chemistry 730 (2013) 90e94
Fig. 1. Solid-state structures of 1 (Z0 ¼ 2). Thermal ellipsoids are drawn at 50%, solvent molecules and anions omitted for clarity. Selected bond lengths (A): Rh1eP1, 2.2707(13);
Rh1eC1, 2.039(5); Rh1eC3, 2.020(5); Rh1eC8, 2.372(5); Rh1eC10, 2.382(5); Rh1eC16, 3.504(6); Rh1eC17, 3.244(6); Rh1eC20, 3.446(6); C8eC10, 1.605(7); Rh2eP2, 2.2749(12);
Rh2eC101, 2.027(5); Rh2eC103, 2.021(5); Rh2eC108, 2.372(5); Rh2eC110, 2.372(5); Rh2eC116, 3.394(6); Rh2eC117, 3.451(6); Rh2eC120, 3.310(6); C108eC110, 1.611(7).
ꢀ
3. Conclusions
We have extended the number of complexes that show Ce
C$$$Rh interactions by the synthesis and characterization of
[Rh(PR3)(BinoreS)][BArF4], R ¼ PtBu2Me, 1; PCy2Ph, 2. When
considered alongside our previous work in the area these studies
show that there is a rather narrow window of phosphine steric
profile that supports the isolation of these interesting complexes,
with the phosphine cone angle lying between 160ꢀ and 170ꢀ.
4. Experimental
4.1. General methods
All manipulations were performed under an atmosphere of
argon, using Schlenk and glove box techniques. Glassware was oven
dried at 130 ꢀC overnight and flamed under vacuum prior to use.
CH2Cl2, hexane and pentane were dried using a Grubbs type solvent
purification system (MBraun SPS-800) and degassed by successive
freezeepumpethaw cycles [42]. C6H5F and CD2Cl2 were dried over
ꢀ
CaH2, vacuum distilled and stored over 3 A molecular sieves. NBD
was degassed by successive freezeepumpethaw cycles and dried
ꢀ
over 3 A molecular sieves. [Rh(NBD)Cl]2 [43], [Rh(NBD)Cl(PPh3)]
[44], [Rh(NBD)Cl(PtBu3)] [45] and Na[BArF4] [46] were prepared
using literature methods. All other chemicals are commercial
Table 1
Comparison of selected structural metrics for the RheBinoreS complexes.
[Rh(PR3)(BinoreS)]þ PiPr3
PCy3
PCyp3
PtBu2Me 1b PCy2Ph 2
a
a
a
ꢀ
RheP/A
2.2693(7) 2.2621(4) 2.2466(7) 2.273(2)
1.604(4) 1.608(3) 1.607(4) 1.608(10)
2.361(4) 2.386(3) 2.352(4) 2.375(10)
2.037(4) 2.026(3) 2.032(3) 2.027(10)
2.2531(9)
1.616(5)
2.370(6)
2.028(5)
ꢀ
C8eC10/A
RheC8/RheC10/Åc
RheC1/RheC3/Åc
Fig. 2. Solid-state structure of 2. Thermal ellipsoids are drawn at 50%, anion omitted
for clarity. Selected bond lengths (A): Rh1eP1, 2.2531(9); Rh1eC1, 2.029(3); Rh1eC3,
2.027(4); Rh1eC8, 2.370(4); Rh1eC10, 2.369(4); Rh1eC16, 3.344(4); Rh1eC32,
3.307(4); C8eC10, 1.616(5).
a
ꢀ
See reference [26].
Averaged over two independent molecules.
Average value.
b
c

A.B. Chaplin, A.S. Weller / Journal of Organometallic Chemistry 730 (2013) 90e94
93
2
t
products and were used as received. NMR spectra were recorded on
a Bruker DRX 500 MHz, Bruker AVC 500 MHz or Varian Mercury VX
300 MHz spectrometers. Chemical shifts are quoted in ppm and
coupling constants in Hz. Microanalyses of 1 and 2 were performed
at Elemental Microanalysis Ltd; all others were performed at the
London Metropolitan University.
tBu{C}), 35.3 (br, C5/12), 33.2 (br, C4/9), 30.5 (d, JPC ¼ 3, Bu{Me}),
26.3 (br d, J ¼ 12, C1/3/8/10), 2.2 (dd, 1JPC ¼ 23, 2JRhC ¼ 3, Me). C2/9 was
not unambiguously located at this temperature.
31P{1H} NMR (CD2Cl2, 202 MHz, 298 K):
d
54.8 (d, 1JRhP ¼ 224,
1P).
Anal. Calcd. for C55H49BF24RhP (1310.65 gmolꢁ1): C, 50.40; H,
3.77; N, 0.00. Found: C, 50.52; H, 3.67; N, 0.00.
4.2. Synthesis of [Rh(NBD)Cl(PR3)]
4.4. Synthesis of [Rh(BINOReS)(PCy2Ph)][BArF4] 2
General procedure: To a solution of [Rh(NBD)Cl]2 (0.150 g,
0.325 mmol) in CH2Cl2 (6 mL) was added PR3 (0.683 mmol) and the
resulting yellow solution stirred at room temperature for 2 h. The
products were obtained either by recrystallization by addition of
hexane (PR3 ¼ PCy2Ph) or by removing the solvent in vacuo and
washing with hexane at low temperature (ꢁ78 ꢀC, PR3 ¼ PiBu3,
PtBu2Me, PAdn2Bu).
To a Schlenk flask charged with [Rh(NBD)Cl(PCy2Ph)] (0.0235 g,
0.047 mmol) and Na[BArF4] (0.0412 g, 0.047 mmol) was added
a solution of NBD (0.1 mL, excess) in C6H5F (3 mL). The resulting
suspension was stirred at RT for 90 min and then filtered. The
filtrate was layered with pentane and held at 5 ꢀC for 72 h to afford
the product as yellow crystals. Yield: 0.044 g (66%).
[Rh(NBD)Cl(PiBu3)] Yield: 75%.
1H NMR (CD2Cl2, 500 MHz, 298 K):
d
7.70e7.74 (m, 8H, ArF),
1H NMR (CDCl3, 300 MHz, 298 K):
d
5.06e5.11 (m, 2H, CH), 3.74e
7.51e7.65 (m, 9H, ArF þ Ph), 3.35 (br, 4H, H1/3/8/10), 2.42 (app. q,
J ¼ 10, 2H, Cy{CH}), 2.31 (br, 2H, H2/9), 2.20 (s, 2H, H5/12), 2.03 (br,
4H, H4/6/11/13), 1.77e1.96 (m, 10H, Cy), 1.43 (br, 4H, H4/9), 1.18e1.52
(m, 10H, Cy).
3.80 (m, 2H, CH), 3.37e3.43 (m, 2H, CH),1.80e1.98 (m, 3H, iBu{CH}),
i
2
3
1.41e1.49 (m, 7H, Bu{CH2} þ CH2), 1.37 (dt, JHH ¼ 8.3, JHH ¼ 1.4,
3
1H, CH2 ), 1.16 (d, JHH ¼ 6.6, 18H, iBu{Me}).
0
31P{1H} NMR (CDCl3, 122 MHz, 298 K):
d
9.2 (d, 1JRhP ¼ 164, 1P).
13C{1H} NMR (CD2Cl2,126 MHz, 298 K):
d
162.3 (q, 1JBC ¼ 50, ArF),
Anal. Calcd for C19H35ClPRh (432.82 gmolꢁ1): C, 52.73; H, 8.15;
N, 0.00. Found: C, 52.84; H, 8.24; N, 0.00.
135.4 (s, ArF), 133.5 (d, 2JPC ¼ 9, Ph), 132.6 (d, 4JPC ¼ 2, Ph), 130.7 (d,
2
3
3JPC ¼ 9, Ph), 129.4 (qq, JFC ¼ 32, JBC ¼ 3, ArF), 125.5 (d, 1JPC ¼ 39,
[Rh(NBD)Cl(PtBu2Me)] Yield: 53%.
Ph), 125.1 (q, 1JFC ¼ 272, ArF), 118.0 (sept, 3JFC ¼ 4, ArF), 43.9 (br, C4/6/
1H NMR (CDCl3, 300 MHz, 298 K):
d 4.97e5.01 (m, 2H, CH),
11/13), 35.3 (br, C5/12), 33.5 (dd, 1JPC ¼ 24, 2JRhC ¼ 2, Cy{CH}), 33.4 (br,
3.70e3.75 (m, 2H, CH), 3.34e3.39 (m, 2H, CH), 1.39 (d app. q,
2
C
4/9), 29.6 (br, Cy), 29.1 (br, Cy), 27.4 (d, JPC ¼ 12, Cy), 27.3 (d,
2
JHH ¼ 8.7, J ¼ 2, 1H, CH2), 1.33 (dt, 2JHH ¼ 8.7, 3JHH ¼ 1.6, 1H, CH2 ),
0
2JPC ¼ 11, Cy), 26.4 (br, Cy), 25.9 (dd, J ¼ 13, J ¼ 4, C1/3/8/10). C2/9 was
3
t
2
3
1.35 (d, JPH ¼ 13.2, 18H, Bu), 0.66 (dd, JPH ¼ 7.0, JRhH ¼ 1.3, 3H,
not unambiguously located at this temperature.
Me).
31P{1H} NMR (CD2Cl2, 202 MHz, 298 K):
d
42.1 (d, 1JRhP ¼ 211, 1P).
31P{1H} NMR (CDCl3, 122 MHz, 298 K):
d
36.9 (d, 1JRhP ¼ 166, 1P).
Anal. Calcd. for C65H58BF24RhP (1439.83 gmolꢁ1): C, 54.22; H,
4.06; N, 0.00. Found: C, 53.88; H, 3.84; N, 0.00.
Anal. Calcd for C16H29ClPRh (390.74 gmolꢁ1): C, 49.18; H, 7.48; N,
0.00. Found: C, 49.29; H, 7.39; N, 0.00.
[Rh(NBD)Cl(PCy2Ph)] Yield: 85%.
1H NMR (CDCl3, 300 MHz, 298 K):
d 7.35e7.46 (m, 5H, Ph), 5.08e
4.5. Crystallography
5.13 (m, 2H, CH), 3.73e3.79 (m, 2H, CH), 3.34e3.39 (m, 2H, CH),
1.10e2.26 (m, 24H, Cy þ CH2).
Data for 1 and 2 (Table 2) were collected on an Enraf Nonius
31P{1H} NMR (CDCl3, 122 MHz, 298 K):
d
31.6 (d, 1JRhP ¼ 166, 1P).
Kappa CCD diffractometer using graphite monochromated Mo K
a
ꢀ
Anal. Calcd for C25H35ClPRh (504.88 gmolꢁ1): C, 59.47; H, 6.99;
N, 0.00. Found: C, 59.56; H, 7.11; N, 0.00.
radiation (
l
¼ 0.71073 A) and a low-temperature device [150(2) K]
[Rh(NBD)Cl(PAdn2Bu)] Yield: 83%.
Table 2
1H NMR (CDCl3, 300 MHz, 298 K):
d 4.84e4.90 (m, 2H, CH),
Crystallographic data for 1 and 2.
3.68e3.74 (m, 2H, CH), 3.55e3.61 (m, 2H, CH), 2.20e2.35 (m, 12H,
Ad), 2.00 (br, 6H, Ad),1.75 (app. q, J ¼ 13,12H, Ad),1.55e1.66 (m, 2H,
1.C6H5F
2
2
nBu{CH2}), 1.41 (d app. q, JHH ¼ 8.7, J ¼ 2, 1H, CH2), 1.24e1.37 (m,
CCDC
Formula
M
897872
C61H54BF25PRh
1406.73
Triclinic
P-1
897873
C64H55BF24PRh
1424.77
Triclinic
P-1
n
3
5H, 2 ꢂ Bu{CH2} þ CH2 ), 0.93 (t, JHH ¼ 7.3, 3H, nBu{Me}).
0
31P{1H} NMR (CDCl3, 122 MHz, 298 K):
d
36.6 (d, 1JRhP ¼ 160, 1P).
Crystal System
Space group
T [K]
Anal. Calcd for C31H47ClPRh (589.05 gmolꢁ1): C, 63.21; H, 8.04;
N, 0.00. Found: C, 63.34; H, 7.94; N, 0.00.
150(2)
150(2)
ꢀ
a [A]
16.9856(3)
19.4486(3)
19.6501(3)
71.3272(8)
75.9809(8)
89.9118(7)
5946.04(16)
4 (Z0 ¼ 2)
1.571
12.4297(2)
13.9045(2)
18.1299(3)
81.1817(10)
77.5303(10)
83.5117(8)
3012.91(8)
2
ꢀ
b [A]
4.3. Synthesis of [Rh(BINOReS)(PtBu2Me)][BArF4] 1
ꢀ
c [A]
a [deg]
a
Schlenk flask charged with [Rh(NBD)Cl(PtBu2Me)]
b
[deg]
To
(0.0200 g, 0.051 mmol) and Na[BArF4] (0.0450 g, 0.051 mmol) was
added a solution of NBD (0.1 mL, excess) in C6H5F (2 mL). The
resulting suspension was stirred at RT for 90 min and then filtered.
The filtrate was layered with pentane and held at 5 ꢀC for 72 h to
afford the product as yellow crystals. Yield: 0.056 g (84%).
g [deg]
3
ꢀ
V [A ]
Z
Density [gcmꢁ3
]
1.571
0.426
m
(mmꢁ1
)
0.433
q
range [deg]
5.10 ꢃ
37148
0.0486
99.0%
q
ꢃ 25.03ꢀ
5.12 ꢃ
17850
0.0288
99.0%
10563/520/913
0.0427
0.1078
1.026
0.906, ꢁ0.662
q
ꢃ 25.03ꢀ
Reflns collected
Rint
Completeness
No. of data/restr/param
R1 [I > 2s(I)]
wR2 [all data]
1H NMR (CD2Cl2, 500 MHz, 298 K): 7.70e7.74 (m, 8H, ArF), 7.56
d
(br, 4H, ArF), 3.18 (br, 4H, H1/3/8/10), 2.34 (br, 2H, H2/9), 2.14 (s, 2H, H5/
3
12), 1.94 (br, 4H, H4/6/11/13), 1.38 (br, 4H, H4/9), 1.35 (d, JPH ¼ 13.6,
20806/805/1760
0.0513
0.1337
1.024
0.735, ꢁ0.594
t
2
18H, Bu), 1.28 (dd, JPH ¼ 9.2, 3JRhH ¼ 2.0, 3H, Me).
13C{1H} NMR (CD2Cl2,126 MHz, 298 K):
d
162.3 (q, 1JBC ¼ 50, ArF),
GoF
135.4 (s, ArF), 129.4 (qq, 2JFC ¼ 32, 3JBC ¼ 3, ArF), 125.2 (q, 1JFC ¼ 273,
ArF), 118.0 (sept, 3JFC ¼ 4, ArF), 43.9 (br, C4/6/11/13), 36.4 (d, 1JPC ¼ 23,
Largest diff. pk and hole [eÅꢁ3
]

94
A.B. Chaplin, A.S. Weller / Journal of Organometallic Chemistry 730 (2013) 90e94
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[47]; data were collected using COLLECT, reduction and cell
refinement was performed using DENZO/SCALEPACK [48]. The
structures were solved by direct methods using SIR2004 [49] and
refined full-matrix least squares on F2 using SHELXL-97 [50]. All
non-hydrogen atoms were refined anisotropically. Hydrogen atoms
were placed in calculated positions using the riding model. Further
details about the refinement, including disorder modelling and
restraints, are documented in the CIF under the heading _refi-
ne_special_details. Crystallographic data have been deposited with
the Cambridge Crystallographic Data Centre under CCDC 897872
and 897873 These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Acknowledgements
The EPSRC for funding (ABC).
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