Synthesis and properties of new tris(cyanoethyl)phosphine complexes of platinum (0,II), palladium (0,II), iridium (I) and rhodium (I). Conformational analysis of tris(cyanoethyl)phosphine ligands

Article abstract of DOI:10.1016/S0022-328X(97)00541-X

The tris(cyanoethyl)phosphine (tcep) complexes trans-[PtCl₂(tcep)₂], cis-[PtMe₂(tcep)₂], and trans-[PtMeCl(tcep)₂] are prepared by treatment of the corresponding [PtXY(cod)] (cod = 1,5-cyclooctadiene) with tcep. Reduction of trans-[PtCl₂(tcep)₂] with NaBH₄ gives trans-[PtHCl(tcep)₂] which, in the presence of tcep and NEt₃, gives the coordinatively unsaturated platinum(0) complex [Pt(tcep)₃]. This coordinatively unsaturated species is also formed when [Pt(norbornene)₃] reacts with tcep. [Pt(tcep)₃] is very unreactive compared to its PEt₃ analogue: it is air-stable and does not react with further tcep to form an 18-electron species. It is protonated by HBF₄ · OEt₂ to form [PtH(tcep)₃]BF₄. The complex trans-[PdCl₂(tcep)₂] is made from [PdCl₂(NCPh)₂] and tcep and the derivatives trans-[PdX₂(tcep)₂] (X = Br or I) are made by metathesis of the dichloro complex. Reduction of trans-[PdCl₂(tcep)₂] with LiOMe in the presence of tcep gave the palladium(0) complex [Pd(tcep)₃] which, like its platinum(0) analogue, undergoes exchange with free tcep on the NMR timescale. The palladium complex reacts with dibenzylideneacetone (dba) to form [Pd(η²-dba)(tcep)₂]; the same product is formed in the reaction of [Pd(η²-dba)₂] and tcep. Reaction of [Pd₂Cl₂(η³-C₃H₃) ₂] and tcep gives [PdCl(tcep)(η³-C₃H₃)] or [Pd(tcep)₂(η³-C₃H₃)]Cl depending on stoichiometry. The rhodium(I) and iridium(I) complexes trans-[MCl(CO)(tcep)₂], [MCl(tcep)(cod)] and [MCl(tcep)₃] are all readily made from tcep and an appropriate precursor. All new compounds have been fully characterised by a combination of elemental analysis, IR, ³¹P, ¹³C, ¹H and ¹⁹⁵Pt NMR spectroscopy. The crystal structure of [IrCl(tcep)₃] as a MeCN solvate shows a distorted square planar coordination geometry (trans angles at Ir(I) ca. 164°, cis P-Ir-P av. 96°, cis P-Ir-Cl av. 85°). Analysis of the conformations of tcep ligands in this and other published tcep complexes shows there is a preference for conformations in which aaa, aag or g⁺g^- (a = anti, g = gauche) arrangements of the three M-P-C-C chains are avoided.

Full text of DOI:10.1016/S0022-328X(97)00541-X

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Journal of Organometallic Chemistry 550 1998 255–266
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Synthesis and properties of new tris cyanoethyl phosphine complexes of
ž / ž / ž / ž /
platinum 0,II , palladium 0,II , iridium I and rhodium I .
1
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/
Conformational analysis of tris cyanoethyl phosphine ligands
)
2
A. Guy Orpen , Paul G. Pringle , Martin B. Smith, Kerry Worboys
School of Chemistry, UniÕersity of Bristol, Cantocks Close, Bristol BS8 ITS, UK
Received 24 February 1997
Abstract
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Ž
.
w
Ž
. x
w
Ž
. x
w
Ž
. x
2
The tris cyanoethyl phosphine tcep complexes trans- PtCl2 tcep , cis- PtMe2 tcep , and trans- PtMeCl tcep are prepared by
2
2
w
Ž
.x Ž
.
w
Ž
Ž .
. x
2
treatment of the corresponding PtXY cod cods1,5-cyclooctadiene with tcep. Reduction of trans- PtCl2 tcep with NaBH4 gives
trans- PtHCl tcep which, in the presence of tcep and NEt3, gives the coordinatively unsaturated platinum 0 complex Pt tcep . This
coordinatively unsaturated species is also formed when Pt norbornene reacts with tcep. Pt tcep is very unreactive compared to its
w
Ž
. x
w
Ž
. x
3
2
w
Ž
. x
w
Ž
. x
3
3
PEt3 analogue: it is air-stable and does not react with further tcep to form an 18-electron species. It is protonated by HBF4POEt2 to form
. x . x . x . x
w
Ž
w
Ž
w
Ž
w
Ž
PtH tcep BF4. The complex trans- PdCl2 tcep is made from PdCl2 NCPh and tcep and the derivatives trans- PdX2 tcep
3
2
2
2
Ž
.
w
Ž
. x
XsBr or I are made by metathesis of the dichloro complex. Reduction of trans- PdCl2 tcep with LiOMe in the presence of tcep
2
Ž .
w
Ž
. x
Ž .
which, like its platinum 0 analogue, undergoes exchange with free tcep on the NMR
gave the palladium 0 complex Pd tcep
timescale. The palladium complex reacts with dibenzylideneacetone dba to form Pd h -dba tcep ; the same product is formed in the
reaction of Pd h -dba and tcep. Reaction of Pd2Cl2 h -C3H3
depending on stoichiometry. The rhodium I and iridium I complexes trans- MCl CO tcep , MCl tcep cod and MCl tcep are all
3
2
Ž
. x
.
w
Ž
.Ž
. x
2
3
2
3
3
w
Ž
. x
w
Ž
Ž .
w
.Ž
Ž
.Ž
.x
w
Ž
. Ž
Ž
.x
and tcep gives PdCl tcep h -C3H3 or Pd tcep h -C3H3 Cl
2
2
2
Ž .
w
Ž
. x w
Ž
.Ž .x
w
. x
3
2
readily made from tcep and an appropriate precursor. All new compounds have been fully characterised by a combination of elemental
analysis, IR, 31P, 13C, H and 195Pt NMR spectroscopy. The crystal structure of IrCl tcep as a MeCN solvate shows a distorted square
1
w
Ž
. x
3
Ž
Ž .
.
planar coordination geometry trans angles at Ir I ca. 1648, cis P–Ir–P av. 968, cis P–Ir–Cl av. 858 . Analysis of the conformations of
tcep ligands in this and other published tcep complexes shows there is a preference for conformations in which aaa, aag or gqgy
Ž
.
asanti, gsgauche arrangements of the three M–P–C–C chains are avoided. q 1998 Elsevier Science S.A.
Ž
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Keywords: Platinum; Palladium; Rhodium; Iridium; Tris cyanoethyl phosphine; Synthesis; Structure; Conformation
1. Introduction
also sharply different from other trialkyl phosphines:
w
x
spectroscopic, structural and theoretical studies 7–13
indicate that tcep has a p-acceptor capacity similar to
w x
Ž
.
Ž
.
Tris cyanoethyl phosphine tcep is produced in
tonne-quantities per annum mainly for use in the photo-
Ž
.
3
P OPh and though Tolman predicted 7 the cone-an-
w
x
w x
graphic industry 1–4 and is thus readily available
commercially. The presence of the b-cyano groups
makes tcep very different from other small trialkylphos-
gle for tcep to be ca. 1328, recently Liu et al. 14 have
shown by crystallography that tcep can have a much
larger cone angle of 1758.
Ž
.
phines: tcep is an air-stable solid m.p.q978C of low
In this paper we report the synthesis and chemistry of
some new platinum, palladium, rhodium and iridium
complexes with tcep which we wanted to screen as
catalyst precursors for hydrophosphination of acryloni-
Ž
.
basicity pKa 1.37 while tri-n-propylphosphine is a
Ž
.
very air-sensitive liquid m.p.y838C of high basicity
Ž
.
w
x
pKa 8.64 5,6 . The coordination chemistry of tcep is
w
x
trile 15 . The conformations of coordinated tcep are
analysed in detail. Previously, other groups have re-
ported aspects of tcep coordination chemistry with plat-
)
Corresponding author.
w
x
w
x
w x
inum 16–25 , palladium 25,26 and rhodium 27 and a
preliminary account of some of this work has been
1 Dedicated to Professor Ken Wade on the occasion of his 65th
birthday.
2 Also corresponding author.
w
x
given 15 .
0022-328Xr98r$19.00 q 1998 Elsevier Science S.A. All rights reserved.

(
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256
A.G. Orpen et al.rJournal of Organometallic Chemistry 550 1998 255–266
Table 1
2. Results and discussion
Elemental analysesa
Ž
.
Ž
.
Tris cyanoethyl phosphine tcep can be conve-
niently made on a large scale by treatment of
C
H
N
Ž
.
.
.
.
.
.
.
.
.
.
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.
.
.
2
3
4
5
38.70 39.30
36.15 36.15
35.00 35.00
41.85 41.65
36.45 36.10
38.05 38.35
33.35 33.10
28.90 28.95
46.55 47.25
56.85 57.70
38.45 38.30
44.60 44.30
42.20 42.10
35.70 35.55
46.10 46.40
38.35 38.60
5.05 4.95
4.40 4.30
4.10 4.10
4.70 4.75
4.35 4.10
4.55 4.30
4.00 3.70
3.45 3.25
5.40 5.25
5.30 5.40
4.55 4.55
5.30 5.15
4.80 4.60
3.90 3.80
5.70 5.50
4.75 4.60
13.75 13.75
13.00 13.30
13.05 13.60
16.30 16.10
w
Ž
. x
Ž
Ž
Ž
P CH2OH Cl with NaOH in the presence of acryloni-
trile 28–30 or is commercially available.
4
x
Ž
Ž
Ž
Ž
w
Ž
Ž
6b
7a
7b
7c
8
Ž
Ž
Ž
13.84 14.05
(
)
2.1. Platinum complexes of tris cyanoethyl phosphine
Ž
Ž
Ž
14.60 14.90
Ž
Ž
Ž
12.40 12.85
The platinum chemistry with tcep is summarised in
Scheme 1 and the characterising data are given in
Tables 1–3.
Ž
Ž
Ž
10.85 11.25
Ž
Ž
Ž
17.65 18.35
Ž
Ž
Ž
11.55 11.40
9
Ž
Ž
Ž
11.25 11.15
10
11
12c
13d
14
15
16e
The dichloroplatinum complex 1 has been previously
Ž
Ž
Ž
14.10 14.75
w
x
w
Ž
.x Ž
reported 16–18 . Treatment of PtCl2 cod cods1,5-
Ž
Ž
Ž
14.80 14.40
.
cyclooctadiene with tcep gives exclusively the trans
Ž
Ž
Ž
12.90 13.10
complex 1 under conditions that many other PR3 lig-
ands e.g., PMe3, PEt3, PBu3, PPh3 would give the cis
isomer; in this reaction tcep behaves like a bulky PR3
Ž
Ž
Ž
.
.
9.05 9.55
Ž
7.65 7.95
16.10 16.10
n
Ž
.
Ž
Ž
Ž
Ž
Ž
.
40.60 40.25
4.60 4.55
w
x
ligand 31 . The crystal structure of 1 does indeed show
that the effective cone angle of the tcep in this complex
aCalculated values in parentheses.
bContains 2H2O, as shown by 1H NMR spectroscopy.
cContains 0.5 Me2CO, as shown by 1H NMR spectroscopy. Cl
w
x
is ca. 1608 18 .
Treatment of PtMe2 cod with tcep gives the ex-
pected cis- PtMe2 tcep
w
Ž
.
x
Ž
.
analysis 6.90 6.40 .
d
Ž
.
Cl analysis 5.75 5.30 .
w
Ž
.
2 x Ž .
2 . The complex trans-
eContains 0.5 MeCN as shown by X-ray crystallography.
w
Ž
Ž
.
x
Ž .
PtMeCl tcep
3 was made by addition of tcep to
w
.
x2
PtMeCl cod ; the formation of the trans isomer 3 is
typical of tertiary phosphines 32,33 but contrasts with
the cis preference of P OR ligands 34 with which
tcep has been compared 7–13 .
The sparingly soluble hydridoplatinum II complex 4
is obtained by treatment of 1 with NaBH4 in MeCN and
has been characterised by elemental analysis, 31 P, 13C
w
x
Ž .
NMR spectroscopy and especially i the IR spectrum
y1
Ž
w
.
w x
Ž
.
Ž
.
nujol mull which had bands at 2245 cm for n PtH ,
3 x
y1
2203 cmy1 for n CN and 285 cm for n PtCl , and
Ž
.
Ž
.
ii the 1H NMR spectrum which showed a hydride
Ž .
Ž .
resonance at dy17.05, a triplet with 195Pt satellites
1
Ž2
Ž
.
Ž
.
.
J HP 14.8 Hz, J HPt 1244 Hz .
Ž
.
Scheme 1. Platinum chemistry with tcep RsCH2CH2CN .

(
)
A.G. Orpen et al.rJournal of Organometallic Chemistry 550 1998 255–266
257
Table 2
equivalents of tcep or by reduction of trans-
195
31 P and Pt NMR dataa
w
Ž
.
x
Ž
PtCl2 tcep with NaBH4 in the presence of tcep see
2
1
Ž .b
d P
Ž
.
Ž .
d Pt
Solvent
J MP
.
Scheme 1 . The assignment of the three-coordination of
1
Ž
Ž
Ž
Ž
.
tcep
1
2
3
4
CD3 2 SO
CD3 2 SO
CD3 2CO
CD3 2CO
y24.0
10.4
13.1
15.8
22.9
38.9
8.3 22
7.3
14.9
the platinum in 5 is based on elemental analysis, H,
13C, 31 P and especially 195Pt NMR spectroscopy: the
.
2483
1814
2942
2808
4236
2585
2100
195
1
.
y151
7
Ž
.
Pt NMR signal for 5 is a quartet with J PtP of 4236
.
1
Ž
.
w
Ž
.3x
Hz, similar to the J PtP of 4188 Hz for Pt PEt3
CD3CN
y475
1
5
6
CD3 2CO
Ž
17c
Ž
.
and quite different from the J PtP of 3727 Hz for
x w x
35 . The IR spectrum of 5 showed a single
Ž
.
.
w
Ž
.
Ž
.
.
CD3 2 SO
y570
Pt PEt3
n CN at 2250 cm
4
y1
Ž
.
consistent with the absence of
Ž
Ž
Ž
.
7a
7b
7c
8
CD3 2 SO
CD3 2 SO
CD3 2 SO
w
x
coordinated cyano groups 36 .
.
12.3
5.9
7.2
The coordinatively unsaturated complex 5 shows no
tendency to bind a fourth tcep ligand: treatment of 5
with 10 equivalents of tcep results in broadened 31 P
.
CD3CN
Ž
.
Ž
9
CD3 2 SO
13.7 15
10.7
19.5
12.4
22.2
18.2
21.3
9.8
33.4 41
17.6
9.6 22
y1.3
Ž
.
NMR resonances for 5 and tcep see Fig. 1 but no
1
Ž
Ž
Ž
Ž
Ž
Ž
Ž
.
10
11
12
13
14
15
16
CD3 2CO
CD3 2 SO
CD3 2CO
CD3 2CO
CD3 2CO
CD3 2CO
CD3 2 SO
Ž .
Ž
.
change in d P or J PtP , consistent with slow phos-
.
phine exchange on the NMR timescale, presumably via
.
120
154
w
Ž
.
x
the transient 18-electron species Pt tcep . Complex 5
.
4
.
is soluble in acetone, acetonitrile and dmso but insolu-
.
Ž
ble in other common organic solvents e.g. CH2Cl2 ,
toluene , it is not protonated by MeOH or H2O and
.
Ž
.
181
134
.
decomposes only very slowly in air even in solution.
These properties of 5 may be contrasted with those of
Ž
.
Ž
.
17
CD3 2 SO
w
Ž
.3x
the extremely air-sensitive analogue Pt PEt3 which
a
31P NMR spectra 36.2 MHz measured at 288C with chemical
Ž
.
w
Ž
.
x
forms Pt PEt3 in the presence of PEt3, is soluble in
4
Ž
. Ž .
in ppm "0.1 to high frequency of 85% H3PO4 and
195
shifts
coupling constants
measured at 288C with chemical shifts
d
most common organic solvents and reacts with methanol
Ž
.
Ž
.
Ž
.
J
in Hz "3 .
Pt NMR spectra 19.2 MHz
w
Ž
.
3xq
w
x
or water to give PtH PEt3
37 .
Ž
.
Ž .
in ppm "0.5 to high
d
Ž .
Ž
.
The platinum 0 complex 5 can be protonated by
HBF4 in diethyl ether to give PtH tcep BF4
frequency of J Pt 21.4 MHz.
b Value in parentheses is J PP .
2
Ž
.
w
Ž
.
x
Ž . Ž
see
6
3
c
Ž
.
In CD3 2 SO.
.
Tables 1–3 for the data .
(
)
Reductive elimination of HCl from 4 is effected by
2.2. Palladium complexes of tris cyanoethyl phosphine
treatment with NEt3 in the presence of tcep to give
w
Ž
.
3x Ž .
Ž .
Pt tcep
5 . The platinum 0 complex 5 can also be
The palladium chemistry is summarised in Scheme 2
and characterising data are given in Tables 1–3. The
2
w
Ž
.3x
prepared by treatment of Pt h -norbornene with 3
Table 3
13C NMR dataa
Solvent
CNb
PCHb2
PCH2CHb2
Otherb
Ž
Ž
Ž
.
Ž
.
.
Ž
.
Ž
13.3 19.4
12.9 29.1
.
.
.
.
tcep
2
3
CD3 2 SO
120.8 10.8
20.6 15.1
d
d
d
e
CD3 2 SO
119.5c
20.0c
17.8
.
Ž
Ž
.
Ž
.
d CH3 4.0 109, 591
e
.
Ž
Ž
Ž
.
Ž
.
CD3 2 SO
119.4 15.4
12.1 32.1
d CH3 -22.1 6, 645
4
CD3CN
120.3 8.0
21.1c
14.1 39.2
Ž .
Ž
Ž
Ž
Ž
Ž
.
Ž
.
.
.
.
.
.
.
Ž
.
.
.
.
.
.
.
7a
7b
7c
10
11f
14
15
CD3 2 SO
CD3 2 SO
CD3 2 SO
CD3 2CO
119.9 15.1
17.4 27.5
11.9
12.2
12.9
.
Ž
Ž
119.8 15.1
19.0 27.5
.
Ž
Ž
23.0 30.3
119.4 17.9
.
Ž
Ž
Ž
.
Ž . Ž . Ž .
d C3H5 79.6 32.3 , 118.3 5.4 , 54.6.
Ž . Ž .
d C3H5 75.2 32.3 , 125.4
119.5 16.2
21.0 22.6
12.9 5.4
13.5
Ž
Ž
CD3CN
120.1 13.1
22.1 24.4
Ž
.
.
Ž
Ž
Ž
.
.
CD3 2 SO
Ž
120.1 16.0
16.9 23.3
12.5 4.0
Ž
12.2 3.3
Ž
Ž
CD3 2 SO
120.1 16.0
16.4 29.3
a
Ž
.
Ž
Ž
.
Ž .
Spectra 67.5 MHz measured at 208C with chemical shifts d are in ppm "0.1 to high frequency of SiMe4 and coupling constants J are in
Ž
.
Hz "3 .
b
Ž
.
The first numbers given are the chemical shifts and the numbers in parentheses are J CP coupling constants unless otherwise stated. The signals
n
nq2
<
Ž
.
Ž
.<
were normally virtual triplets and the coupling constants listed are J PC q
J PC .
cComplex multiplet.
d 3
Ž
.
J PtC .
e The figures in parentheses are J PC and then J PtC .
2
1
Ž
.
Ž
.
f The BPh4 salt was used for this spectrum.

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258
A.G. Orpen et al.rJournal of Organometallic Chemistry 550 1998 255–266
elemental analysis, 31 P and 13C NMR spectroscopy.
The 31 P NMR spectrum of the filtrate consisted
of a singlet at 42.9 ppm which was assigned to
Ž
.
w x
OsP CH2CH2CN . Mason and Verkade 26 previ-
3
w
Ž
.
x
ously observed the formation of Pd tcep upon treat-
ment of trans- PdCl2 tcep with F but the complex
x
y
w
Ž
.
x
2
was not isolated and x was not defined; since their data
concur with ours for 8, we can conclude that xs3. The
31 P NMR spectrum of 8 in the presence of tcep shows
broad signals for 8 and free tcep showing that, like its
platinum analogue 5, phosphine exchange is occurring
on the NMR timescale but there is no evidence for the
w
Ž
.
x
formation of a stable Pd tcep species.
. 4Ž
.
x
Ž
dba s
2
w
Ž
The complex Pd tcep h -dba
9
2
.
dibenzylideneacetone was formed upon addition of 2
2 x
w
Ž
.
equivalents of tcep to Pd dba
or one equivalent of
Ž
.
dba to complex 8 see Scheme 2 and has been isolated
and fully characterised. When 7 equiv. of tcep is added
to solutions of 9, broadened 31 P NMR signals for 9 and
tcep are observed indicating tcep exchange on the NMR
timescale; however, no signal for 8 was detected show-
ing that, like other bulky PR3 complexes of the type
2
w
Ž
. Ž
.
x w
x
Pd PR3 h -dba 38,39 the coordinated dba in 9 is
2
not susceptible to substitution.
Ž .
3
w
Ž
.Ž
The allylpalladium II complexes PdCl tcep h -
3
.
x
Ž
.
w
Ž
. Ž
.
x
Ž
.
C3H5
made by treatment of Pd2 h-Cl h -C3H5 with 1 or
10 and Pd tcep h -C3H5 Cl 11 were
2
3
w
Ž
. Ž
. x
2
2
Ž
2 equivalents of tcep see Scheme 2 and Tables 1–3 for
the data . The ionic species 11 is water soluble and the
.
anion can be readily exchanged for BPh4 by treatment
of aqueous solutions of 11 with NaBPh4. Addition of an
3
w
Ž
. x
excess of tcep to Pd2Cl2 h -allyl in ethanol gave 8
2
Ž
w
a similar reduction occurs with other phosphines 40–
42 but the palladium 0 product was not obtained in
pure form using this route.
x.
Ž .
2.3. Rhodium and iridium complexes of
(
)
tris cyanoethyl phosphine
The rhodium and iridium chemistry is summarised in
Scheme 3 and characterising data are given in Tables
31
w
Ž
. x Ž .
Ž .
Fig. 1. P NMR spectra of Pt tcep
5 in the presence of a no
3
Ž .
Ž .
c
Ž .
.
tcep;
b
1 equiv. tcep;
3 equiv. tcep; d 10 equiv. tcep.
w
Ž
.Ž .2 x
1–3. The complexes trans- MCl CO tcep
MsRh
12 or M s Ir 13 are made by treatment of
4 x . Ž 2 x
Ž
Xsimpurity peak 2% intensity of signal for 5
Ž
.
Ž
.
w
Ž
.
w
Ž
.
Rh2Cl2 CO
.
in acetone. The chloro-bridges in M2 m-Cl cod
or IrCl CO p-toluidine
with tcep
. Ž 2 x
are cleaved by addition of 2 equivalents of tcep to give
.Ž
2
w
Ž
2
w
x
w
Ž
.
2 x
Ž
.
previously reported 26 trans- PdCl2 tcep
made from PdCl2 NCPh and tcep; the corresponding
dibromo 7b and diiodo 7c complexes were made by
metathesis of 7a with LiBr and LiI respectively. The
trans geometry in 7a–c is confirmed by the appearance
7a was
w
Ž
. x
w
Ž
.
x
Ž
.
Ž
.
Ž 4
MCl cod tcep MsRh 14 or MsIr 15 .
2
Ž
.
Ž
.
w
Ž
. Ž
.
x
Treatment of Rh2 m-Cl cyclooctene
with 6
3x
2
w
.
Ž
.
16
equivalents of tcep in acetone gave RhCl tcep
as unambiguously identified from the doublet of triplets
and doublet of doublets observed in the 31 P NMR
spectra of the reaction solutions. However we were
unable to obtain this compound in analytically pure
13
Ž
of virtual triplets in the C NMR spectra see Tables
.
1–3 for the characterising data . Treatment of trans-
2 x
w
Ž
.
Ž
.
7a with LiOMe in the presence of 2
PdCl2 tcep
equivalents of tcep gave a yellow solid to which we
3x Ž .
condition because of the presence of small amounts
31
w
Ž
.
Ž
.
assign the structure Pd tcep
8 on the basis of
-5% by P NMR spectroscopy of unidentified

(
)
A.G. Orpen et al.rJournal of Organometallic Chemistry 550 1998 255–266
259
Ž
.
Scheme 2. Palladium chemistry with tcep RsCH2CH2CN .
Ž
.
Scheme 3. Rhodium and iridium chemistry with tcep RsCH2CH2CN .

(
)
260
A.G. Orpen et al.rJournal of Organometallic Chemistry 550 1998 255–266
rhodium-containing impurities. The iridium analogue
3x
tcep conformations in metal complexes has been noted
w
Ž
.
Ž
.
w
Ž
w x
IrCl tcep
. Ž
17 was made similarly from Ir2 m-
previously. Thus Liu et al. 14 reported that the P–C–
.
4 x
and tcep in MeCN. The orange
Cl cyclooctene
C–CN conformations were typically a mix of gauche
2
q
torsion angles ca. 608 or y608, g or gy or anti
Ž
Ž
.
solid product was air stable and formed crystals from
MeCN solution suitable for X-ray crystallography.
.
torsion angles near "1808, a . However, it is clear that
to describe the conformational behaviour of these lig-
ands and in turn their cone angles the M–P–C–C
torsion angles must be taken into account as well. Thus
[
(
) ]
2.4. X-ray crystal structure of IrCl tcep 3 P0.5 Mecn
Ž
.
Fig. 2 shows the molecular structure of complex 17
present in the crystal and Table 4 gives important
structural parameters. As expected, the iridium is square
planar with small deviations from ideal coordination
geometry and the Ir–P distances reflect the low trans
Ž
in 17 while all the P–C–C–CN conformations bar one
.
of the disordered chains are anti, in each tcep ligand
one Ir–P–C–C chain is anti, and the other two are
q
gauche either g or gy . The cone angles for these
Ž
.
Ž
Ž .
Ž
.
influence of chloride Ir–P trans to Cls2.218 3 , trans
tcep ligands were calculated as ur2s u1 qu2 qu3 r3
where ui is the angle subtended by the van der Waals
envelope of the ith PCCCN chain. The resultant cone
˚
Ž .
.
to tcep av. 2.310 3 A . The P–Ir–P angles are distorted
from ideal values as might be expected due to the bulk
Ž
Ž . Ž .
Ž .
of the tcep ligands av. cis P–Ir–P 968, av. cis P–Ir–Cl
858 . The deviations from ideal geometry at Ir are most
marked in the trans angles which are folded to ca.
1648 so as to reduce the pseudo-symmetry at Ir from
D4h as in an ideal square planar environment and the
crowding in the coordination plane. One of the tcep
ligands shows a disorder affecting the conformation of
angles for the tcep ligands of P 1 , P 2 and P 3 are
X
.
w
Ž
.
Ž
.x
147 for either C 14 or C 14 , 146 and 1498 respec-
tively. The effect of the Ir–P–C–C conformations are
notable with those which are anti leading to lower ui of
ca. 608 and those which are gauche having ui ca. 808.
Still larger ui are possible if the ‘umbrella’ conforma-
tion is adopted in which all three M–P–C–C are gy
Ž
.
Ž
.
and all three P–C–C–CN are gq as in Ag tcep
.
2 xq
w
Ž .
x
Ž
w
Ž
one PCCCN chain at P 1 , the two images differ in the
X
Ž Ž
.
Ž
.
w
x. Ž
positions of the a carbons C 14 and C 14 and the
cyano groups.
14 or in its enantiomeric form where the signs of all
.
torsion angles are reversed .
As reflected in the torsion angle data given in Table
4 the tcep ligands adopt a variety of conformations
about the P–C and C–C CN bonds. The variability of
In order to explore the generality of these observa-
tions, those crystal structures containing tcep coordi-
nated to transition elements were retrieved from the
Ž
.
Ž
.
Fig. 2. Molecular structure of 17 showing labelling scheme. All hydrogen atoms have been omitted for clarity

(
)
A.G. Orpen et al.rJournal of Organometallic Chemistry 550 1998 255–266
261
Table 4
Selected bond distances
from the crystal structure of 17P0.5 MeCN
and ti to P–C–C–C torsions in the ith chain M–P–C–
C–CN of an M-tcep fragment. As usual the conforma-
tion space has a 3608 periodicity in all dimensions.
1. v1, v2 , v3; t1, t2 , t3
2. v2 , v3, v1; t2 , t3, t1
3. v3, v1, v2; t3, t1, t2
˚
Ž .
Ž
.
Ž
.
A
angles deg and torsion angles deg
Ž .
Ž .
2.318 3
Ir–P 1
Ž .
Ž .
2.321 3
Ir–P 2
Ž .
Ž .
2.218 3
Ir–P 3
Ž .
2.386 3
Ir–Cl
4. yv1, yv3, yv2; yt1, yt3, yt2
5. yv2 , yv1, yv3; yt2 , yt1, yt3
6. yv3, yv2 , yv1; yt3, yt2 , yt1
If each torsion angle is assumed to take either anti
a , or gauche positive g or gauche negative g
then there are seven unique possible conformer types in
Ž .
Ž .
Ž .
164.8 1
P 1 –Ir–P 2
Ž .
Ž .
Ž .
94.9 1
P 1 –Ir–P 3
Ž . Ž .
Ž .
97.5 1
P 2 –Ir–P 3
Ž .
Ž .
83.4 1
P 1 –Ir–Cl
q
y
Ž .
Ž .
87.2 1
P 2 –Ir–Cl
Ž .
Ž . .
Ž
.
Ž
Ž .
163.6 1
P 3 –Ir–Cl
Ž .
Ž
.
Ž
.
Ž .
y57.9 3
Ir–P 1 –C 11 –C 12
Ž
.
respect of the sets of three M–P–C–C v conforma-
tions as listed below.
Ž .
Ž
.
Ž
.
Ž
.
.
Ž .
175.9 3
P 1 –C 11 –C 12 –C 13
Ž .
Ž
.
Ž
.
.
Ž
Ž .
y67.3 5
Ir–P 1 –C 14 –C 15
Ir–P 1 –C 14 –C 15
A aaa
X
Ž .
Ž
.
Ž
Ž
Ž .
y28.2 5
y
y y
B gqgqgq 'g g g
Ž
.
Ž .
Ž
.
.
Ž .
178.8 5
P 1 –C 14 –C 15 –C 16
q
q
q
q
q
q
y
y
y
y
y y
X
X
Ž
.
C g g a 'g ag ; ag g ; g g a; g ag ; ag g
Ž .
Ž
.
Ž
.
Ž
.
Ž .
y77.7 6
P 1 –C 14 –C 15 –C 16
q
q
q
y
y
y
Ž .
Ž
.
Ž
.
Ž .
166.0 3
Ir–P 1 –C 17 –C 18
Ž
.
D g aa 'aag ; ag a; g aa; aag ; ag a
q
y
y
q
q
y
q
Ž .
Ž
.
Ž
.
Ž
Ž .
177.9 3
P 1 –C 17 –C 18 –C 19
Ž
Ž
.
E g g a 'g ag ; ag g
Ž .
Ž
.
Ž
.
Ž .
60.0 3
Ir–P 2 –C 21 –C 22
y
q
q
y
y
.
F g g a 'g ag ; ag g
Ž .
Ž
.
Ž
.
Ž
.
.
.
.
.
.
Ž .
y166.6 3
P 2 –C 21 –C 22 –C 23
G gy gq gq ' g g g ; gq gqgy; gy gy gq;
q
y q
Ž
Ž .
Ž
.
Ž
.
Ž .
38.6 3
Ir–P 2 –C 24 –C 25
gygqgy; gqgygy
A similar classification of the sets of three P–C–C–C
.
Ž .
Ž
.
Ž
.
Ž
Ž .
173.6 3
P 2 –C 24 –C 25 –C 26
Ž .
Ž
.
Ž
.
Ž .
y179.5 3
Ir–P 2 –C 27 –C 28
Ž .
Ž
Ž .
.
Ž
.
Ž
Ž .
y178.7 3
P 2 –C 27 –C 28 –C 29
Ž
.
conformations torsion angles t is also possible. In the
Ž
.
Ž
Ž
.
Ž
Ž .
54.8 3
Ir–P 3 –C 31 –C 32
Ž
.
case of 17 the Ir–P–C–C v conformer types are C, C
Ž . Ž . Ž .
Ž .
Ž
.
.
Ž .
y164.6 3
P 3 –C 31 –C 32 –C 33
and F for P 1 , P 2 and P 3 , respectively. For each
Ž .
Ž
.
Ž
.
Ž .
y59.8 3
Ir–P 3 –C 34 –C 35
X
Ž
Ž
.
Ž .
.
tcep except the C 14 image of the P 1 ligand as
noted above all three P–C–C–C conformations are anti
leading to a fuller description for the tcep ligand confor-
Ž .
Ž
.
Ž
.
Ž
Ž .
166.8 3
P 3 –C 34 –C 35 –C 36
Ž .
Ž
.
Ž
.
Ž .
y170.0 3
Ir–P 3 –C 37 –C 38
Ž .
Ž
.
Ž
.
Ž
Ž .
y170.3 3
P 3 –C 37 –C 38 –C 39
Ž
Ž
.
.
Ž
mation as CrA for the C 14 image or CrD for the
X
Ž
.
.
C 14 image , CrA and FrA for the three tcep lig-
ands, where the first letter refers to the set of torsions,
v, about P–C bonds and the second to the set of C–C
conformations, t. Note that the ‘umbrella’ conforma-
Ž
.
Cambridge Structural Database see Section 4 . For a
conformation space such as that for tcep there are six
symmetry equivalent conformations 43,44 as listed
w
x
w
x
tion 14 would be of type BrB and the fully inverted
below, in which vi refer to M–P–C–C torsion angles
umbrella ArA in this notation.
Table 5
Ž
.
M–P–C–C and P–C–C–CN torsion angles in M tcep complexes in the CSD
Refcodea
v1
v2
v3
t1
t2
t3
Conformer type
ACNICP
BEFDIZ01
BEFDIZ01
BEFDIZ02
CIZNII
y61.6
y70.3
50.6
63.0
54.8
y174.8
y52.7
61.7
56.6
y62.2
44.7
176.5
y42.8
y45.8
y44.8
58.5
56.7
y47.7
68.5
y177.9
53.3
51.7
y49.9
y169.6
32.0
48.3
60.5
y43.8
y42.8
64.4
y44.8
45.7
y51.1
178.5
y176.2
170.1
y58.6
54.2
173.2
178.9
174.6
67.1
84.4
78.9
179.0
169.7
171.1
172.6
y173.6
171.3
y171.9
y176.9
y178.9
y166.1
y178.2
75.7
y166.4
179.4
167.9
y58.0
FrD
CrD
CrF
CrF
BrA
CrA
CrD
FrD
GrD
GrE
BrD
CrA
BrB
GrA
BrD
BrA
GrE
y60.6
y180.0
y176.1
y177.2
y170.1
y66.2
y66.7
61.5
62.0
149.5
75.7
179.0
70.5
175.1
174.6
74.4
179.8
y169.9
y70.9
177.5
176.7
75.7
y171.0
179.4
175.4
75.4
CIZNII
51.9
CIZNOO
CYEPNI
LESNOM
LESNOM01
LEXXOB
LEXXOB
PERFEX
PERFOH
TNITPP
177.5
y57.9
y60.1
38.7
58.5
y54.3
y42.8
y45.2
y44.8
47.2
179.4
y87.1
y174.5
TNITPP
ZOZFUP
y39.9
58.0
a
w
x
From Ref. 45,46 .

(
)
262
A.G. Orpen et al.rJournal of Organometallic Chemistry 550 1998 255–266
formers is perhaps not unexpected in view of the high
energy of gqgy interactions in organic chemistry as in
Ž
.
w x
1,3 diaxial cyclohexanes . See Ref. 47 for an example
of the consequences of such interactions in controlling
the conformations of alkyl chains attached to quaternary
centres. The additional repulsive effects due to the
electrostatic interactions between cyano groups seem
likely to enhance these effects.
For any given M–P–C–C–CN chain there are five
unique conformation types arising from combinations of
v and t which are a, gq or gy, as listed below for
Fig. 3. Labelling scheme for torsion angles describing the M–P–C–C
Ž
.
Ž .
v
and P–C–C–CN t conformations.
Ž
.
which the M–P–C–C v conformation is given first as
elsewhere.
For the 17 unique tcep ligands located in the CSD
see Section 4, Table 5, Fig. 3 conformer types may be
assigned by this procedure. The v conformer types B,
H ara
y
I argq 'arg
Ž
.
Ž
Ž
.
q
y
.
J g ra 'g ra
K gqrgq 'g rg
y
y
Ž
Ž
Ž
.
C, F and G are observed 5, 6, 2 and 4 examples,
L gqrgy 'g rg
y
q
.
.
respectively , but there are no A, D or E types in the
Ž
.
Ž
.
Ž
list. In contrast for the P–C–C–CN torsions, t, there
In 17 only type H 3 times , J 6 times and for one
Ž
.
are examples of type A, B, D, E, and F 5, 1, 7, 2 and 2
of the disordered chains K chain conformations are
.
examples, respectively and no examples of types C and
observed. As shown in Fig. 4 all of these combinations
are observed in the data set of 17 tcep ligands drawn
from the CSD. Overall there are 26 chains of type J and
11 of type L, 6 of type H, and 2 each of types I and K.
On the basis of this rather slight evidence there seems to
be some local preference for types J and L although
molecular and presumably crystal environment can
clearly induce other combinations. Overall in the data
set there are 8 anti and 39 gauche conformations at the
P–C bonds, and 32 anti and 15 gauche conformations
D. While any conclusions drawn from such a small data
set must be very tentative, it seems likely that the
missing conformer types are likely to be higher in
energy than the observed ones, and that the more com-
mon ones be of relatively low energy. The absence of
Ž
.
any aaa or aag v conformers types A and D imply
that inter-chain interactions must be important. These
are precisely the conformations that would lead to small
cone angles and there absence is consistent with the
ability of tcep to shield low coordination number metals
Ž
.
at the C–C CN bonds. While these individual bond
conformation frequencies may say something about their
energetic preferences, it is clear that it is important to
Ž .
Ž .
such as the three coordinate Pt 0 and Pd 0 species
reported in this paper. The absence of type E v con-
Fig. 4. Plot of t vs. v for all M–PCCCN fragments located in the CSD after symmetry expansion and application of 3608 periodicity.

(
)
A.G. Orpen et al.rJournal of Organometallic Chemistry 550 1998 255–266
263
[
(
) ] ( )
consider the way that torsion angles are combined when
analysing the conformational preferences of this type of
ligand. A complete analysis of the combinations of v
and t triples has not been carried out here because of
the paucity of data. A more detailed study of these
preferences for more plentiful ligands such as PEt3 or
4.1. Preparation of trans- PtCl2 tcep 2
1
Ž
.
A solution of tcep 413 mg, 2.14 mmol in CH2Cl2
6 cm was added dropwise over 3 min to a solution of
PtCl2 cod 400 mg, 1.07 mmol in CH2Cl2 20 cm
to give an off-white solid which was filtered off, washed
with CH2Cl2 1 cm and then dried in vacuo. The
3
Ž
w
.
3
Ž
.
x
Ž
.
Ž
.
3
Ž
.
P OR would seem warranted. We note that similar
Ž
.
.
3
conformational behaviour is seen in other recently re-
ported structures of tcep complexes not yet in the CSD:
Ž
product 650 mg, 93% was identified as 1 by compari-
son of its NMR spectra with the literature 16,17 .
w
x
w
Ž
.
x
Ž
.
w
x w .2 x Ž
Ž
.
Ž
AuBr tcep GrE 48 ; Au tcep PAu CN
BrA
x w .2 x Ž
and CrA 49 ; Mo2Cl4 tcep NCR RsMe, Br
2
.
w
Ž
. Ž
2
[
(
) ] ( )
4.2. Preparation of cis- PtMe2 tcep 2
2
i
.
Ž
.
Ž
A and BrA , RsEt CrA and CrA , RsPr CrA
.
w x
and CrA 50 .
Ž
.
Ž
A solution of tcep 326 mg, 1.87 mmol in acetone 5
cm3 was added to a solution of PtMe2 cod 312 mg,
.
w
Ž
.x Ž
3
.
Ž
.
0.936 mmol in acetone 20 cm and the resulting
colourless solution was stirred for 10 min. The solution
was then concentrated to 1–2 cm3 and the white prod-
3. Conclusion
Ž
uct was precipitated by addition of diethyl ether 30
From the chemistry described here, two striking fea-
tures of the coordination chemistry of tcep have
cm3 and then filtered off, washed with diethyl ether 5
.
.
Ž
1
cm3 and dried in vacuo 554 mg, 97% . H NMR 270
Ž
.
Ž
Ž .
emerged: i tcep can stabilise low valent metals which
Ž
.
.
Ž
Ž
MHz, CD3 2CO : 2.88 and 2.50 complex multiplets,
coordinated tcep resonances 0.43 br. s, J PtH 62.1
Hz, Pt-C H3 . Other characterising data are given in
is manifest in the high air-stability of the complexes
2
.
Ž
.
Ž .
Ž .
Ž . Ž .
with platinum 0 , palladium 0 and iridium I ; ii tcep
can stabilise coordinative unsaturation as observed in
.
Ž .
Ž .
Tables 1–3.
the 3-coordinate palladium 0 and platinum 0 com-
plexes. These properties are more reminiscent of a
phosphite or a bulky phosphine ligand than of a small
trialkyl phosphine. Thus our results provide further
experimental support for the idea that the b-cyano
[
(
) ] ( )
4.3. Preparation of trans- PtMeCl tcep 2
3
Ž
.
A solution of tcep 163 mg, 0.844 mmol in acetone
5 cm was added to a solution of PtMeCl cod 149
mg, 0.421 mmol in acetone 10 cm and the resulting
colourless solution was stirred for 10 min. The solution
was then concentrated to 1–2 cm3 and the white prod-
3
Ž .
substituents
i may engender significant p-acceptor
Ž
.
w
Ž
.x Ž
3
Ž .
capacity on tcep and ii make the cone angle of tcep
much greater than would be predicted from a simple
model because of repulsive CN PPP CN electrostatic
forces.
.
Ž
.
Ž
uct was precipitated by addition of diethyl ether 30
cm3 and then filtered off, washed with diethyl ether 5
.
.
Ž
1
cm3 and dried in vacuo 240 mg, 90% . H NMR 270
Ž
.
Ž
Ž
.
.
Ž
MHz, CD3 2CO : 2.98 and 2.58 complex multiplets,
4. Experimental
3
.
Ž
Ž
.
coordinated tcep resonances ; 0.50 d, J PH 6.4 Hz,
2
Ž
.
.
J PtH 80.1 Hz, Pt-C H3 . Other characterising data are
All reactions were carried out under a nitrogen atmo-
sphere unless otherwise stated and solvents dried, when
necessary, by refluxing over the appropriate drying
given in Tables 1–3.
[
(
) ] ( )
Ž
4.4. Preparation of PtHCl tcep 2 4
reagents calcium hydride for dichloromethane,
sodiumrbenzophenone for diethyl ether, toluene and
.
Ž
.
n-hexane and distilled under nitrogen prior to use.
Sodium borohydride 30 mg, 0.793 mmol was added
Commercial reagents were used as supplied unless oth-
in small portions over 10 min to a solution of trans-
500 mg, 0.828 mmol in acetonitrile 30
cm . The solution was stirred for 1 h and then the
w
Ž
.
x
w
Ž
.
2 x
Ž
. Ž
erwise stated; the phosphonium salt P CH2OH Cl
PtCl2 tcep
4
3
.
was obtained from Albright and Wilson as an 80%
Ž
. Ž
.
solution in water and from this, P CH CH2CN tcep
made by the literature method 28–30 or obtained from
Strem Chemicals. The following starting materials were
solvent was evaporated to dryness under reduced pres-
3
x2
3
w
Ž
.
sure. Water 30 cm was added to the residue and the
white solid was filtered off in air, washed with methanol
3
3
w
Ž
.
x
Ž
.
Ž
.
prepared according to literature methods: PtCl cod
20 cm , diethyl ether 30 cm and then dried in vacuo
x 2
w
x
1
w
w
w
w
w
x
w
Ž
.
x
w
x
w
Ž
.Ž
.
Ž
.
Ž
51 , PtMe2 cod
52 , PtCl CH 3 cod
53 ,
.
to give the product 360 mg, 71% . H NMR 270
MHz, CD3CN : 2.76 and 2.36 complex multiplets,
Ž
.
x w x w
4
2 x
Ž
.
x w x w
Ž
2 x
x
.
Ž
Pt norbornene
54 , PdCl2 NCPh
x w x w
55 , Pd dba
3
. Ž2
.
x w
2
x w
Ž
.
Ž
.
Ž
Ž
.
56 , Rh2Cl2 CO
57 , IrCl CO p-toluidine 58 ,
coordinated tcep resonances ; y17.05 t, J PH 14.8
2
1
Ž
.
w
4
x
w
Ž
.
2 x
w
x
Ž
.
.
Ž
Ž
R h 2 C l 2 cod
59 ,
x w x w
Ir2 C l 2 cod
61 , Ir2Cl2 cyclooctene
60 ,
x w x
60 .
Hz, J PtH 1244 Hz, Pt–H . IR nujol mull, CsI
.. ..
plates, cmy1 : 2245 m, n CN , 2203 m, n PtH , 285
Ž
.
Ž
.
.
Ž
Ž
Ž
Rh2Cl2 cyclooctene
4

(
)
264
A.G. Orpen et al.rJournal of Organometallic Chemistry 550 1998 255–266
Ž
Ž
..
m, n PtCl . Other characterising data are given in
and LiI respectively. See Tables 1–3 for characterising
data.
Tables 1–3.
[
(
) ] ( )
[ (
) ] ( )
5
4.8. Preparation of Pd tcep 3
8
4.5. Preparation of Pt tcep 3
Ž
A solution of lithium methoxide in methanol 0.1 M,
Ž .
Ž .
A solution of tcep 1.220 g, 6.31 mmol in
a
3
3
.
Ž
32.0 cm , 3.19 mmol was added to dry ethanol 30
Ž
.
acetone 20 cm was added dropwise over 1 min to a
solution of Pt norbornene
toluene 80 cm to give a yellow precipitate immedi-
ately. After stirring the mixture for 3 h, the yellow solid
was filtered off under nitrogen. The product 5 was
cm3 and then trans- PdCl2 tcep
450 mg, 0.798
.2 x Ž
.
w
Ž
w
Ž
.
3x
Ž
.
1.008 g, 2.11 mmol in
3
.
Ž
.
mmol and tcep 324 mg, 1.68 mmol were added. The
solution was refluxed for 2 h to afford a yellow precipi-
Ž
.
tate which, when cool, was filtered off, washed with
diethyl ether 20 cm and dried in vacuo 506 mg,
3
3
Ž
.
Ž
Ž
.
purified by dissolving it in acetone 60 cm and then
3
.
92% . See Tables 1–3 for characterising data.
Ž
.
Ž
adding toluene 100 cm to reprecipitate it 1.405 g,
y1
.
Ž
.
Ž
.
86% . IR nujol mull showed n CN at 2250 cm
.
2
[
(
)(
) ] ( )
Other characterising data are given in Tables 1–3.
4.9. Preparation of trans- Pd h -dba tcep 2
9
Ž .
Ž
.
b Sodium borohydride 30 mg, 0.793 mmol was
w
Ž
.
2 x
Ž
174 mg, 0.266
added to a suspension of PtCl2 tcep
Ž
.
2
A solution of tcep 283 mg, 1.466 mmol in acetone
3
.
Ž
.
Ž
mmol and tcep 54 mg, 0.280 mmol in ethanol 14
Ž
.
w
Ž
.2 x Ž
6 cm was added to a solution of Pd h dba 40
cm3 and the mixture was heated to 608C and stirred for
.
Ž
.
3
.
mg, 0.100 mmol in toluene 40 cm and immediately
a yellow precipitate formed with an orange solution.
70 min and then allowed to cool to room temperature.
The yellow precipitate was filtered off, redissolved in
acetone 10 cm and reprecipitated by addition of
The mixture was stirred for 2 h and then the yellow
solid was filtered off, washed with toluene 2 cm and
dried in vacuo 355 mg, 70% . See Tables 1–3 for
characterising data.
3
3
Ž
.
Ž
.
3
Ž
.
Ž
.
diethyl ether 20 cm to give pure 5 206 mg, 65% .
Ž .
Ž
.
c Complex 5 was the only phosphorus-containing
product observed by 31 P NMR spectroscopy when a
3
Ž
.
Ž
solution of 4 24 mg, 0.039 mmol and tcep 8 mg,
0.041 mmol in CD3 2 SO 0.4 cm was treated with
triethylamine 0.020 cm .
[
(
)(
)] (
)
4.10. Preparation of trans- PdCl h -C3 H3 tcep 10
3
.
Ž
.
Ž
.
3
Ž
.
Ž
.
Ž
3
A solution of tcep 196 mg, 1.01 mmol in acetone 5
cm3 was added to
a solution of Pd2Cl2 h -
.
w
Ž
3
[
(
) ]
( )
.
x
Ž
. Ž .
4.6. Preparation of PtH tcep 3 BF4 6
C3H3
185 mg, 0.506 mmol in acetone 10 cm and
2
the resulting pale yellow solution was stirred for 10
min. The solution was then concentrated to 1 cm3 and
3
Ž
.
85% HBF4 in diethyl ether 0.040 cm , 0.238 mmol
was added to a solution of Pt tcep
w
Ž
.
3x
Ž
the yellow product was precipitated by addition of
diethyl ether 20 cm and then filtered off, washed with
diethyl ether 5 cm and dried in vacuo 353 mg, 93% .
IR nujol mull, CsI plates, cm : 2250 m, n CN ,
125 mg, 0.161
3
3
Ž
Ž
.
.
Ž
.
mmol in acetone 6 cm and the resulting colourless
solution was stirred for 10 min. The solution was then
3
.
Ž
.
..
y1
concentrated to 1–2 cm3 and the white product was
Ž
Ž
.
Ž
Ž
3
Ž
..
Ž
.
290 m, n PdCl . Other characterising data are given in
precipitated by addition of diethyl ether 20 cm and
then filtered off, washed with diethyl ether 2 cm and
3
Ž
Ž
.
Tables 1–3.
1
Ž
.
dried in vacuo 108 mg, 77% . H NMR 270 MHz,
3
Ž
.
.
Ž
CD3 2 SO : 2.78 and 2.51 complex multiplets, coordi-
[
(
)(
) ]
(
)
4.11. Preparation of trans- Pd h -C3 H3 tcep 2 Cl 11
2
.
Ž
.
Ž
.
nated tcep resonances ; y7.06 t, J PH 157.5, and
1
Ž
.
15.7 Hz, J PtH 760 Hz, Pt–H . Other characterising
Ž
.
3
A solution of tcep 345 mg, 1.792 mmol in acetone
10 cm was added to a solution of Pd2Cl2 h -C3H3
162 mg, 0.448 mmol in acetone 10 cm and the
resulting mixture was stirred for 10 min. The white
3
data are given in Tables 1–3.
Ž
Ž
.
w
Ž
.2 x
3
.
Ž
.
[
(
) ] ( )
4.7. Preparation of trans- PdCl2 tcep 2 7a
Ž
solid product was filtered off, washed with acetone 1
cm3 and dried in vacuo 279 mg, 55% . See Tables
1–3 for characterising data.
.
Ž
.
Ž
.
A solution of tcep 534 mg, 2.76 mmol in CH2Cl2
3
Ž
.
10 cm was added dropwise over 3 min to a solution
2 x
w
Ž
.
Ž
.
of PdCl2 NCPh
530 mg, 1.38 mmol in CH2Cl2
10 cm and the mixture stirred for a further 10 min.
The yellow solid product was filtered off, washed with
3
[
(
)( ) ] ( )
4.12. Preparation of trans- RhCl CO tcep 2 12
Ž
.
3
Ž
.
Ž
Ž
.
Ž
CH2Cl2 1 cm and then dried in vacuo 762 mg,
A solution of tcep 78 mg, 0.400 mmol in acetone 2
cm3 was added to a solution of Rh2Cl2 CO
40 mg,
.
Ž
.
Ž
.
.
w
Ž
.
4 x
Ž
98% . The corresponding bromo 7b and iodo 7c
3
.
Ž
.
complexes were made in 82 and 96% yields by treat-
ment of 7a in CH2Cl2 with acetone solutions of LiBr
0.100 mmol in acetone 10 cm and the resulting
solution was stirred for 40 min. The solvent was then

(
)
A.G. Orpen et al.rJournal of Organometallic Chemistry 550 1998 255–266
265
˚
Ž
.
evaporated to dryness to give the yellow solid product
91 mg, 82% . See Tables 1–3 for characterising data.
Ka X-rays ls0.71073 A using a Siemens four-circle
R3mrV diffractometer. Cell dimensions were deter-
mined from setting angles of 25 reflections. A total of
6508 intensity data were collected for a hemisphere of
reciprocal space 2u-50.08 by ur2u scans and cor-
rected for Lorentz, polarisation, long-term intensity de-
cay of 8.9%, and for absorption effects on the basis of
azimuthal scan data. Of the data, 6106 were unique
Ž
.
[
(
)( ) ] ( )
4.13. Preparation of trans- IrCl CO tcep 2 13
Ž
.
Ž
A solution of tcep 55 mg, 0.240 mmol in acetone 2
cm3 was added to a solution of IrCl CO p-toluidine
.
w
Ž
. Ž
.
x
2
3
Ž
.
Ž
.
48 mg, 0.120 mmol in acetone 10 cm and the
Ž
.
resulting solution was stirred for 2 h. The solution was
Rint 0.023 . The structure was solved by Patterson
methods, and refined by full-matrix least-squares against
F against all 4675 data with I)1.5s I with weights,
3
Ž
then concentrated to ca. 1 cm and then pentane 30
cm3 added to give the yellow solid product 58 mg,
75% . IR nujol mull, CsI plates, cm : 2245 m,
n CN , 1955 s, n CO . Other characterising data are
.
Ž
Ž .
y1
2
w
2Ž
.
xy1
.
Ž
.
Ž
w, set equal to sc Fo qgFo
, where gs0.0008.
Ž
..
Ž
Ž
..
All non-hydrogen atoms heavier than carbon were re-
fined without positional constraints and assigned
given in Tables 1–3.
Ž
anisotropic displacement parameters except for the sol-
[
(
)( )] ( )
.
4.14. Preparation of RhCl tcep cod 14
vent nitrogen . All carbon atoms were refined without
positional constraints and atoms C16, C16X, C19, C23,
C26, C29, C33, C36, C39, were assigned anisotropic
displacement parameters. Disorder was modelled in one
Ž
.
A solution of tcep 138 mg, 0.714 mmol in acetone
3
Ž
.
w
Ž
.2 x Ž
4 cm was added to a solution of Rh2Cl2 cod 175
mg, 0.355 mmol in acetone 10 cm and the resulting
3
.
Ž
.
Ž Ž ..
tcep ligand P 1 with a two-site model used to de-
scribe the positions of C14, C16, N12 occupancy
w
solution was stirred for 15 min. The solution was then
X
X
X
3
Ž
Ž .
x
w
Ž .x
concentrated to ca. 1 cm and then diethyl ether 25
0.48 1 and C14 , C16 and N12 occupancy 0.52 1 .
The acetonitrile of crystallisation is disordered about a
centre of inversion with atoms having occupancy 0.5.
All hydrogen atoms were assigned fixed isotropic dis-
placement parameters and were constrained to ideal
geometries. Final difference syntheses showed no chem-
ically significant features, the largest being close to the
metal atom. Refinements converged to residuals Rs
cm3 added to give the yellow solid product 292 mg,
93% . The iridium analogue 15 was made similarly
from IrCl tcep cod in 82% yield. See Tables 1–3 for
characterising data.
.
Ž
.
w
Ž
.Ž
.x
[
(
) ] (
)
4.15. Preparation of IrCl tcep 3 17
3
w
Ž
.
4 x
Ž
.
.
Solid Ir2Cl2 cyclooctene
119 mg, 0.133 mmol
0.0556, Rw s0.0572, Ss1.17. Complete atomic co-
Ž
was added to a solution of tcep 157 mg, 0.813 mmol
ordinates, displacement parameters, bond distances and
angles have been deposited. All calculations were made
3
Ž
.
in acetonitrile 20 cm and the resulting solution was
stirred for 30 min. The solution was then slowly con-
centrated under reduced pressure until orange crystals
w
x
with programs of the SHELXTL-PLUS system 62 .
Complex neutral-atom scattering factors were taken from
Ž
.
w
x
separated from the solution. The product 220 mg, 59%
was then filtered off. The rhodium analogue 16 was
4 x
Ref. 63 .
w
Ž
.
made similarly Rh2Cl2 cyclooctene
in acetone in
4.17. Data retrieÕal
65% yield but was not obtained free from an impurity
. x
assigned to the O2 adduct RhCl O2 tcep .
3
w
Ž
.Ž
w
Ž
.x
Crystal structures containing the fragment M tcep
Ž
.
Mstransition metal were located from the Cam-
[
(
) ]
Ž
.
4.16. Structure determination of IrCl tcep
0.5MeCN 17 P0.5 MeCN
P
bridge Structural Database CSD using the QUEST
3
(
)
w
x
program 45,46 . Data for these crystal structures were
retrieved from the October 1996 version of CSD. The
data files retrieved were screened and only structures
which fulfilled all of the following criteria were retained
for further analysis.
Crystals suitable for X-ray crystallography were
obtained by slow evaporation of MeCN solutions
of 17 under reduced pressure. Crystal data:
C28 H37.5ClIrN9.5P3, Ms827.74, triclinic, space group
1. R factorF0.11
˚
˚
Ž .
Ž
.
Ž .
P1 No. 2 , as9.373 4 A, bs12.301 5 A, cs
2. Atomic coordinates included in CSD.
3. No disorder within the fragment
4. ‘perfect match’ between crystallographic and chemi-
cal connectivity, and no errors by CSD definitions.
The final data files contained 17 fragments from 11
˚
Ž .
Ž .
Ž .
16.645 6 A, a s 74.26 3 8, b s 85.41 3 8, g s
3
˚
.
Ž .
Ž
69.07 3 8, Vs1725.49 1.31 A , Zs2, Dc s1.35 g
cmy3, ms4.1 mmy1, F 000 s854, Ts295 K, crys-
tal size 0.24=0.24=0.12 mm, index ranges y12Fh
F12, y15FkF15, y20FlF20; transmission coef-
ficient range 0.47–0.96. X-ray diffraction measurements
on a single crystal mounted in a thin-walled glass
capillary were made with graphite monochromated Mo–
Ž
.
3
2
2
1r2
2
<
<
<
<
w
x
w Ž
; Ss ÝwD r N.O.–
RsÝ D rÝ Fo ; wRs ÝwD rÝwFo
N.V. 1r2; Ds Fo – Fc.
.x

(
)
266
A.G. Orpen et al.rJournal of Organometallic Chemistry 550 1998 255–266
w
x
25 A.J. Blake, G.P. McQuillan, J. Chem. Soc., Dalton Trans.
Ž
structures. The values of the torsion angles ti, is1,3;
Ž
.
1984 1849.
.
vi, is1,3 were calculated for each fragment with
w
w
w
w
w
w
x
Ž
.
26 M.R. Mason, J.G. Verkade, Organometallics 11 1992 2212.
27 M.A.S. Aquino, D.H. Macartney, Inorg. Chem. 26 1987 2696.
28 E. Wolf, M. Reuter, Ger. Pat. 1 082 910 1961 to Hoechst.
29 E. Wolf, M. Reuter, Chem. Abs., 55 1961 16 422e.
30 W.J. Vullo, Ind. Eng. Chem., Prod. Res. Dev. 5 1966 346.
31 C.A. McAuliffe, W. Levason, Phosphine, Arsine and Stibine
PCCCN chains numbered 1–3 anti-clockwise as viewed
in Fig. 4.
x
Ž
.
x
Ž
.
x
Ž
.
x
Ž
.
x
Acknowledgements
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1979.
w
w
w
x
Ž . Ž
.
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.
33 J.A. Davies, F.R. Hartley, Chem. Rev. 81 1981 79.
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