Synthesis and reactivity of dichloroboryl complexes of platinum(II)

Article abstract of DOI:10.1039/b612039n

The reaction between [Pt(nbe)₃] (nbe = norbornene), two equivalents of the phosphines PPh₃, PMePh₂ or PMe ₂Ph and 1 equivalent of BCl₃ affords the platinum dichloroboryl species [PtCl(BCl₂)(PPh₃)₂], [PtCl(BCl₂)(PMePh₂)₂] and [PtCl(BCl ₂)(PMe₂Ph)₂]. All three complexes were characterised by X-ray crystallography and reveal that the boryl group lies trans to the chloride. With PMe₃ as the phosphine, the complex [PtCl(BCl₂)(PMe₃)₂] is isolated in high yield as a white crystalline powder although crystals suitable for X-ray crystallography were not obtained. Crystals were obtained of a product shown by X-ray crystallography to be the unusual dinuclear species [Pt ₂(BCl₂)₂(PMe₃)₄(-Cl)] [BCl₄] which reveals an arrangement in which two square planar platinum(ii) centres are linked by a single bridging chloride which is trans to a BCl₂ group on each platinum centre. The reaction of [PtCl(BCl ₂)(PMe₃)₂] with NEt₃ or pyridine (py) affords the adducts [PtCl{BCl₂(NEt₃)}(PMe ₃)₂] and [PtCl{BCl₂(py)}(PMe₃) ₂], respectively, both characterised spectroscopically. The reaction between [PtCl(BCl₂)(PMe₃)₂] and either 4 equivalents of NHEt₂ or piperidine (pipH) results in the mono-substituted boryl species [PtCl{BCl(NEt₂)}(PMe₃) ₂] and [PtCl{BCl(pip)}(PMe₃)₂], respectively, the former characterised by X-ray crystallography. Treatment of either [PtCl(BCl₂)(PMe₃)₂] (in the presence of excess NEt₃) or [PtCl{BCl(NEt₂)}(PMe₃)₂] with catechol affords the B(cat) (cat = catecholate) derivative [PtCl{B(cat)}(PMe₃)₂] which is also formed in the reaction between [Pt(PMe₃)₄] and ClB(cat) and also from the slow decomposition of [Pt{B(cat)}₂(PMe₃)₂] in dichloromethane over a period of months. The compound [Pt{B(cat)} ₂(PMe₃)₂] was prepared from the reaction between [Pt(PMe₃)₄] and B₂(cat)₂. This journal is The Royal Society of Chemistry.

Full text of DOI:10.1039/b612039n

View Article Online / Journal Homepage / Table of Contents for this issue
PAPER
www.rsc.org/dalton | Dalton Transactions
Synthesis and reactivity of dichloroboryl complexes of platinum(II)
Jonathan P. H. Charmant, Cheng Fan, Nicholas C. Norman* and Paul G. Pringle*
Received 4th September 2006, Accepted 16th October 2006
First published as an Advance Article on the web 6th November 2006
DOI: 10.1039/b612039n
The reaction between [Pt(nbe)3] (nbe = norbornene), two equivalents of the phosphines PPh3, PMePh2
or PMe2Ph and 1 equivalent of BCl3 affords the platinum dichloroboryl species [PtCl(BCl2)(PPh3)2],
[PtCl(BCl2)(PMePh2)2] and [PtCl(BCl2)(PMe2Ph)2]. All three complexes were characterised by X-ray
crystallography and reveal that the boryl group lies trans to the chloride. With PMe3 as the phosphine,
the complex [PtCl(BCl2)(PMe3)2] is isolated in high yield as a white crystalline powder although crystals
suitable for X-ray crystallography were not obtained. Crystals were obtained of a product shown by
X-ray crystallography to be the unusual dinuclear species [Pt2(BCl2)2(PMe3)4(l-Cl)][BCl4] which reveals
an arrangement in which two square planar platinum(II) centres are linked by a single bridging chloride
which is trans to a BCl2 group on each platinum centre. The reaction of [PtCl(BCl2)(PMe3)2] with NEt3
or pyridine (py) affords the adducts [PtCl{BCl2(NEt3)}(PMe3)2] and [PtCl{BCl2(py)}(PMe3)2],
respectively, both characterised spectroscopically. The reaction between [PtCl(BCl2)(PMe3)2] and either
4 equivalents of NHEt2 or piperidine (pipH) results in the mono-substituted boryl species
[PtCl{BCl(NEt2)}(PMe3)2] and [PtCl{BCl(pip)}(PMe3)2], respectively, the former characterised by
X-ray crystallography. Treatment of either [PtCl(BCl2)(PMe3)2] (in the presence of excess NEt3) or
[PtCl{BCl(NEt2)}(PMe3)2] with catechol affords the B(cat) (cat = catecholate) derivative
[PtCl{B(cat)}(PMe3)2] which is also formed in the reaction between [Pt(PMe3)4] and ClB(cat) and also
from the slow decomposition of [Pt{B(cat)}2(PMe3)2] in dichloromethane over a period of months. The
compound [Pt{B(cat)}2(PMe3)2] was prepared from the reaction between [Pt(PMe3)4] and B2(cat)2.
derived from the reaction between [CoH(dppe)2] and BX3.3,5 These
Introduction
latter complexes were reported to be particularly versatile boryl
transfer agents, the complex trans-[Co(BBr2)2(dppe)2] being used
to synthesise complexes of rhodium, copper and silver containing
the BBr2 ligand.3,5 Nevertheless, despite the impressive number
of reports, none of these early compounds were structurally
characterised and, partly on the basis of the 11B NMR data
presented, some doubt remains as to their correct formulation.
More recent work has provided the first definitive char-
acterisation of dihaloboryl species. Thus, the first struc-
turally characterised BF2 complexes cis-[Pt(BF2)2(PPh3)2],
[Pt(BF2)2(dppb)] (dppb = 1,2-bis(diphenylphosphino)butane) and
fac-[Ir(BF2)3(CO)(PPh3)2] were recently described by us derived
from the oxidative addition of B2F4 to Pt(0) and Ir(I) precursors
respectively;6 spectroscopic data for an iridium BF2 complex
[IrH(BF2)(PMe3)(g-C5Me5)] had previously been reported by
Bergman and co-workers.7 In 2000, the osmium dichloroboryl
complex [OsCl(BCl2)(CO)(PPh3)2] (dB 52.5) was described by
Roper et al. having been prepared from the reaction between
[OsCl(Ph)(CO)(PPh3)2] and HBCl2.Et2O.8 This and a number of
subsequent reports revealed a rich chemistry of the BCl2 ligand
involving substitution at boron and resulting in a range of new
boryl, tethered boryl and base-stabilised borylene complexes of
osmium.8,9 In 2002, Aldridge reported spectroscopic data for
the cyclopentadienyl complex [Fe(BCl2)(CO)2(g-C5H5)] (dB 90.7),10
originally described by No¨th and Schmid,3 obtained from the re-
action between BCl3 and Na[Fe(CO)2(g-C5H5)]. This was followed
by a theoretical study on a range of similar metal boryl complexes,
including BF2 and BCl2 examples, designed to probe the nature
of the metal–boron bond.11 More recently, Braunschweig and
Transition metal boryl compounds1 remain a focus of continued
interest not least because of their involvement in various metal
catalysed diboration and other borylation reactions.2 In most
examples, the boron of the boryl ligand is bonded to a single metal
centre and two additional atoms which are usually good p-donors
such as oxygen or nitrogen incorporated into diolato or amido
groups respectively; the B(cat) group, where cat = catecholate, is
one of the most studied.1 More recent investigations, notably by
Braunschweig et al. and Aldridge et al., have focussed on more
reactive boryl species in which the R groups of the BR2 ligand are
hydrocarbyl and/or halogeno groups.
With particular reference to dihaloboryl ligands, BX2 (X =
F, Cl, Br, I), the earliest examples were reported by No¨th
and Schmid in the 1960’s.3 Thus in a series of papers, re-
viewed in ref. 3, these authors described a range of dichlorobo-
ryl species including [Co(BCl2)(CO)3(L)] (L = CO, PPh3,
AsPh3), [Mn(BCl2)(CO)4(PPh3)], [Fe(BCl2)(CO)2(g-C5H5)] and
[Mo(BCl2)(CO)3(g-C5H5)] each derived from the reaction between
BCl3 and the corresponding metal carbonylate anion. Alterna-
tively, dihaloboryl species were reportedly formed via B–X bond
(X = halide) oxidative addition to Pt(0) or Co(0) centres, exam-
ples being the Pt(II) species [PtBr(BBr2)(PPh3)2] and the Co(II),
formally 19-electron, complexes [CoX(BX2)(dppe)2] (X = Cl, Br,
I; dppe = 1,2-bis(diphenylphosphino)ethane),3,4 both proposed
to have a cis configuration. The bis-boryl, 19-electron Co(II)
complexes trans-[Co(BX2)2(dppe)2] (X = Br, I) were also described,
University of Bristol, School of Chemistry, Bristol, UK BS8 1TS
114 | Dalton Trans., 2007, 114–123
This journal is
The Royal Society of Chemistry 2007
©

View Article Online
1
co-workers have presented structural data for [Fe(BCl2)(CO)2(g-
C5H5)] (dB 90.0), the first dichloroboryl complex to be structurally
characterised.12 These authors also reported the structure of the 4-
picoline adduct [Fe{BCl2(4-pic)}(CO)2(g-C5H5)] (dB 18.8) in which
the nitrogen atom is directly bonded to the boron centre.12 In later
reports, Braunschweig and co-workers have described the anal-
ogous pentamethylcyclopentadienyl complexes [Fe(BCl2)(CO)2(g-
C5Me5)] (dB 94.9)13 and [Fe(BBr2)(CO)2(g-C5Me5)] (dB 94),14 the
former affording, on reaction with [Pd(PCy3)2], the heteronuclear
complex [(g-C5Me5)Fe(l-CO)2(l-BCl2)Pd(PCy3)] (dB 72.2) con-
taining a bridging dichloroboryl ligand.13 Spectroscopic data were
also presented for the phosphine adduct [Fe{BCl2(PCy3)}(CO)2(g-
C5Me5)] (dB 3.4).13 Both the cyclopentadienyl and pentamethyl-
cyclopentadienyl iron dichloroboryl compounds have also been
employed as precursors in the synthesis of dinuclear species
containing substituent-free bridging boron atoms.15
In most of the recent studies, and much of the early work
reported by No¨th and Schmid, the dihaloboryl species were
prepared from a reaction between a boron trihalide and an anionic
transition metal complex. The exceptions to this method involved
an oxidative addition reaction either of a B–B bond, in the case
of the BF2 complexes,6 or of a boron–halogen bond in the case
of some of the platinum and cobalt complexes described by No¨th
and Schmid.3 In view of the known facile oxidative addition of
B–X bonds to Pt(0), exemplified by the synthesis of such com-
pounds as [PtCl{B(cat)}(PPh3)2],16 [PtCl{BCl(NMe2)}(PPh3)2]17
and [PtBr{BBr(Fc)}(PCy3)2] (Fc = ferrocenyl; Cy = cyclohexyl)18
from ClB(cat), 1,2-B2Cl2(NMe2)2 and BBr2(Fc) respectively, we
were interested in establishing whether dihaloboryl compounds
could be accessed directly from Pt(0) precursors and boron
trihalides. Herein we describe the results of those studies.
with the presence of a BCl2 ligand (dB 62.2, JPtB 1214 Hz; dP
−14.6, 1JPtP 2635 Hz). Attempts to crystallise 1 from this reaction
mixture were unsuccessful, resulting only in small quantities of
the species [PtCl(PMe3)3][BCl4], although isolated yields of 1 as
a white powder were typically >90%. [PtCl(PMe3)3][BCl4] was
characterised by X-ray crystallography, details for which are given
in Table 1.
Similar reactions employing the phosphines PPh3, PMePh2,
PMe2Ph and PCy3 (Cy = cyclohexyl) were also carried out.
For PPh3 and PMePh2 the adducts Ph3PBCl3 and Ph2MePBCl3
were formed (the former characterised crystallographically)
in addition to boryl products identified spectroscopically as
1
[PtCl(BCl2)(PPh3)2] (2) [dB 59(br); dP 23.0, JPtP 3023 Hz] and
[PtCl(BCl2)(PMePh2)2] (3) [dB 61(br); dP 7.6, JPtP 2890 Hz]
1
although in both these cases, the boryl signals in the 11B
NMR were broad and no coupling to platinum was resolved.
Attempted crystallisation of 2 and 3 resulted only in the complexes
[PtCl(PPh3)3][BCl4] and [Pt2(l-Cl)2(PMePh2)4][BCl4]2; the latter
characterised by X-ray crystallography, details for which are given
in Table 1. No spectroscopic evidence was observed for plat-
inum boryl complexes when reactions involving the phosphines
PMe2Ph and PCy3 were carried out, the only isolated products
being PhMe2PBCl3 and [Pt2Cl2(l-Cl)2(PCy3)2] respectively, both
identified by X-ray crystallography.
In all of the reactions carried out above, it was the tetraphos-
phine Pt(0) species, generated in situ, which was employed as
the platinum starting material and BCl3 was added in the molar
ratio 4B : 1Pt. These reactions were attempted in light of some
of the earlier studies referenced above but whilst they afforded
the desired dichloroboryl species in some cases, the products were
difficult to isolate not least because of the presence of the co-
formed phosphine–BCl3 adducts. Reactions were therefore carried
out in which only two equivalents of phosphine were added to the
Pt(0) species [Pt(nbe)3] followed by one equivalent of BCl3. Thus
reaction between [Pt(nbe)3], two equivalents of the phosphines
PPh3, PMePh2 or PMe2Ph and one equivalent of BCl3 afforded,
in each case, high yields of the dichloroboryl species 2, 3 and
[PtCl(BCl2)(PMe2Ph)2] (4) [dB = 61.8 (br); dP −6.7, 1JPtP 2731 Hz].
However, under similar conditions using PMe3, although
31P NMR spectroscopy showed the presence of 1, the solutions
decomposed rapidly to platinum metal. When an excess of BCl3
was used, the unusual dinuclear species 5 was formed (see below).
Results and discussion
We were not the first to examine the reactions between phosphine–
Pt(0) complexes and boron trihalides. Indeed, the reaction between
BBr3 and [Pt(PPh3)4] in cyclohexane, reported by No¨th, Schmid
and co-workers3,4 and mentioned above in the Introduction,
was purported to give the Pt(II) complex [PtBr(BBr2)(PPh3)2].
However, in subsequent work by Durkin and Schram19 and later
Wallbridge and co-workers,20 compounds formulated as Lewis
acid–base adducts were described. Thus Durkin and Schram
reported that treatment of solid [Pt(PPh3)3] with gaseous BCl3
afforded the 1 : 2 adduct (Ph3P)3Pt·2BCl3, the same species being
formed, along with Ph3P·BCl3, when [Pt(PPh3)4] was employed.19
This 1 : 2 adduct was apparently unstable with respect to ligand
dissociation when dissolved in a solvent and when the reaction
between [Pt(PPh3)3] and BCl3 was carried out in benzene solution,
a product formulated as (Ph3P)Pt·BCl3 was proposed. In the later
work by Wallbridge and co-workers,20 the reaction between either
[Pt(PPh3)4] or [Pt(PPh3)2(g-C2H4)] and BF3 in toluene was reported
to afford the adduct (Ph3P)2Pt·2BF3 which was shown to react with
BCl3 to give (Ph3P)2Pt·2BCl3.
The complexes 2, 3 and 4 were characterised by X-ray crystallog-
raphy, the results for which are shown in Fig. 1–3; crystallographic
data for all complexes are presented in Table 1. All three molecules
(two per asymmetric unit for 4) adopt similar structures in the
solid state in which the boryl group is trans to the chloride,
consistent with the known high trans influence of boryl ligands.1,21
The Pt–B bond distances (2, 1.972(3); 3, 1.988(3); 4, 1.963(6),
In this study, the reaction between [Pt(PMe3)4] (prepared in situ
from [Pt(nbe)3] (nbe = norbornene) and four equivalents of PMe3),
and four equivalents of BCl3 in toluene afforded the phosphine
adduct Me3PBCl3 (dB 0.86, 1JPB 164.7) and a platinum boryl species
formulated as [PtCl(BCl2)(PMe3)2] (1), the 11B NMR chemical
shift and well resolved coupling to platinum being consistent
˚
1.971(6) A) are all similar but markedly shorter than the Pt–B dis-
16
˚
tance in trans-[PtCl{B(cat)}(PPh3)2] (2.008(8) A) although the
This journal is
The Royal Society of Chemistry 2007
Dalton Trans., 2007, 114–123 | 115
©

View Article Online
116 | Dalton Trans., 2007, 114–123
This journal is
The Royal Society of Chemistry 2007
©

View Article Online
Fig. 3 A view of the molecular structure of compound 4. Selected bond
◦
˚
length (A) and angle ( ) data include: Molecule 1 Pt(1)–B(1) 1.963(6),
Pt(1)–Cl(1) 2.4385(15), Pt(1)–P(1) 2.3065(15), Pt(1)–P(2) 2.3003(15),
B(1)–Cl(2) 1.794(7), B(1)–Cl(3) 1.778(7); Cl(1)–Pt(1)–B(1) 176.8(2),
P(1)–Pt(1)–P(2) 176.22(5), Cl(2)–B(1)–Cl(3) 111.2(3), Pt(1)–B(1)–Cl(2)
124.9(4), Pt(1)–B(1)–Cl(3) 123.9(4); interplanar angle 85.8. Molecule
2 Pt(2)–B(2) 1.971(6), Pt(2)–Cl(4) 2.4433(15), Pt(2)–P(3) 2.3017(15),
Pt(2)–P(4) 2.2994(15), B(2)–Cl(5) 1.780(7), B(2)–Cl(6) 1.782(7);
Cl(4)–Pt(2)–B(2) 173.3(2), P(3)–Pt(2)–P(4) 175.46(5), Cl(5)–B(2)–Cl(6)
111.4(3), Pt(2)–B(2)–Cl(5) 125.1(4), Pt(2)–B(2)–Cl(6) 123.5(4); interplanar
angle 92.8.
Fig.
1
A
view of the molecular structure of compound 2. Se-
lected bond length (A) and angle (◦) data include: Pt(1)–B(1)
1.972(3), Pt(1)–Cl(1) 2.4368(8), Pt(1)–P(1) 2.3005(7), Pt(1)–P(2) 2.2950(7),
B(1)–Cl(2) 1.791(3), B(1)–Cl(3) 1.779(3); Cl(1)–Pt(1)–B(1) 173.03(8),
P(1)–Pt(1)–P(2) 169.45(2), Cl(2)–B(1)–Cl(3) 113.12(4), Pt(1)–B(1)–Cl(2)
119.85(14), Pt(1)–B(1)–Cl(3) 127.03(15); interplanar angle 81.0.
˚
Pt–Cl distances are more comparable (2, 2.4368(8); 3, 2.4461(8); 4,
16
˚
2.4385(15), 2.4433(15); [PtCl{B(cat)}(PPh3)2] 2.4446(14) A). In
the complex trans-[PtCl{BCl(NMe2)}(PPh3)2],17 the Pt–B and Pt–
˚
Cl distances are 2.075(10) and 2.470(2) A, respectively, revealing
that the Pt–B bond length is broadly correlated with the expected
Lewis acidity of the boryl group, i.e. shorter for a more Lewis
acidic boron. Each boron centre in 2, 3 and 4 is trigonal planar,
the Cl–B–Cl angle being a little less than 120◦ and the two Pt–
B–Cl angles being slightly greater (the slight asymmetry in 2
and 3 is not present in 4); a similar set of angles is observed
for [Fe(BCl2)(CO)2(g-C5H5)].12 In all cases, the angle between the
mean platinum square plane and the mean boron trigonal plane
is close to 90◦ (2, 81.0; 3, 92.7; 4, 85.8, 92.8◦) which compares
with the corresponding angles for [PtCl{B(cat)}(PPh3)2] (78.3◦)16
and [PtCl{BCl(NMe2)}(PPh3)2] (90.0◦).17 We note a recent report
from Marder and co-workers21 describing DFT studies on Pt(II)
boryl species of the type [PtCl(BR2)(PMe3)2]. The trends observed
experimentally in the Pt–B and Pt–Cl bond lengths are in full
accord with those predicted by the DFT calculations. Thus the
trans influence of the B(cat) and BCl2 groups was calculated to be
nearly identical, whilst shorter Pt–B distances were anticipated for
21
˚
˚
Pt–BCl2 (1.976 A) vs. Pt–B(cat) (2.005 A).
Reactions involving the diphosphines dppe (1,2-bis(diphenyl-
phosphino)ethane) and dppm (bis(diphenylphosphino)methane)
were also carried out. Thus reaction between [Pt2(dppm)3]
and BCl3 afforded a mixture of products, one of which was
shown by X-ray crystallography to be the dppm–BCl3 adduct
Cl3BP(Ph)2CH2(Ph)2PBCl3, details of which are given in Table 1.
Fig.
2
A
view of the molecular structure of compound 3. Se-
lected bond length (A) and angle (◦) data include: Pt(1)–B(1)
1.988(3), Pt(1)–Cl(1) 2.4461(8), Pt(1)–P(1) 2.2961(9), Pt(1)–P(2) 2.3005(9),
B(1)–Cl(2) 1.789(3), B(1)–Cl(3) 1.757(3); Cl(1)–Pt(1)–B(1) 173.25(9),
P(1)–Pt(1)–P(2) 173.51(2), Cl(2)–B(1)–Cl(3) 113.57(18), Pt(1)–B(1)–Cl(2)
119.16(18), Pt(1)–B(1)–Cl(3) 127.27(17); interplanar angle 92.7.
˚
This journal is
The Royal Society of Chemistry 2007
Dalton Trans., 2007, 114–123 | 117
©

View Article Online
Crystals of the unusual dinuclear species [Pt2(BCl2)2(PMe3)4(l-
Cl)][BCl4] (5) were obtained. A view of the structure of the cation is
shown in Fig. 4 which reveals an arrangement in which two square
planar platinum(II) centres are linked by a single bridging chloride
which is trans to a BCl2 group on each platinum centre. Both Pt–
86.3◦). Whilst the mechanism by which compound 5 is formed is
unclear, a formal equation for its formation, eqn (1), is consistent
with the expected high trans influence of the boryl groups resulting
in the lability of a trans chloride which is subsequently scavenged
by BCl3.
˚
B bonds [1.960(5) and 1.955(4) A] are similar in length to those
observed for 2, 3 and 4 as are the Pt–Cl bond lengths [2.5155(10)
˚
and 2.5088(11) A]; the boron trigonal planes are also close to
orthogonal with respect to the platinum square planes (89.4 and
2 [PtCl(BCl2)(PMe3)2] + BCl3 →
[Pt2(BCl2)2(PMe3)4(l-Cl)][BCl4]
(1)
Having a reliable route to quantities of [PtCl(BCl2)(PMe3)2]
(1), enabled a study of its reactivity to be carried out which
is summarised in Scheme 1. Thus treatment of 1 with NEt3 or
pyridine (py) afforded the adducts [PtCl{BCl2(NEt3)}(PMe3)2] (6)
1
(dB 27.8; dP −13.0, JPtP 2643 Hz) and [PtCl{BCl2(py)}(PMe3)2]
(7) (dB 29.9, 1JPtB 957; dP −10.4, 1JPtP 2694 Hz) respectively, both
characterised spectroscopically. Proposed structures for 6 and 7
are shown in the diagrams below consistent both with the 11B
NMR data and the known structure of the species [Fe{BCl2(4-
pic)}(CO)2(g-C5H5)].12 Treatment of 1 with dppm afforded a
mixture of products of which only the salt [Pt(PMe3)2(dppm)]Cl2
was characterised; X-ray crystallographic data for this species are
given in the Experimental section.
Fig. 4 A view of the molecular structure of compound 5. Selected bond
◦
˚
length (A) and angle ( ) data include: Pt(1)–B(1) 1.960(5), Pt(2)–B(2)
1.955(4), Pt(1)–Cl(3) 2.5155(10), Pt(2)–Cl(3) 2.5088(11), B(1)–Cl(1)
1.759(5), B(1)–Cl(2) 1.778(5), B(2)–Cl(4) 1.780(5), B(2)–Cl(5) 1.771(5);
B(1)–Pt(1)–Cl(3) 175.54(13), P(1)–Pt(1)–P(2) 176.11(4), B(2)–Pt(2)–Cl(3)
171.40(13), P(3)–Pt(2)–P(4) 168.70(4), Pt(1)–Cl(3)–Pt(2) 126.48(4); inter-
planar angles 89.4 [B(1)] and 86.3 [B(2)].
Scheme 1
118 | Dalton Trans., 2007, 114–123
This journal is
The Royal Society of Chemistry 2007
©

View Article Online
The reaction between 1 and either four equivalents of NHEt2 or
piperidine (pipH) resulted in the mono-substituted boryl species
1
trans-[PtCl{BCl(NEt2)}(PMe3)2] (8) (dB 35.9, JPtB 1028; dP 13.1,
1JPtP 2772 Hz) and [PtCl{BCl(pip)}(PMe3)2] (9) (dB 34.3; dP
1
−9.9, JPtP 3000 Hz) respectively, the eliminated HCl in each
case removed as [NH2Et2]Cl or [pipH2]Cl. Even with sufficient
diethylamine or piperidine present, no evidence was obtained for
a disubstituted boryl species. Spectroscopic data for 8 and 9 were
consistent with the proposed structures and compound 8 was also
characterised by X-ray crystallography, the results of which are
shown in Fig. 5. The structure of 8 is similar to those of 2, 3 and 4
described above. Notable differences, however, are the longer Pt–B
Fig. 5 A view of the molecular structure of compound 8. Selected
bond length (A) and angle (◦) data include: Pt(1)–B(1) 2.005(4),
˚
Pt(1)–Cl(1) 2.4604(10), Pt(1)–P(1) 2.2835(10), Pt(1)–P(2) 2.2795(10),
B(1)–Cl(2) 1.843(5), B(1)–N(1) 1.394(6); Cl(1)–Pt(1)–B(1) 178.86(15),
P(1)–Pt(1)–P(2) 178.33(4), Cl(2)–B(1)–N(1) 115.5(3), Pt(1)–B(1)–Cl(2)
117.1(2), Pt(1)–B(1)–N(1) 127.4(3); interplanar angle 90.0.
˚
and Pt–Cl bond lengths [2.005(4) and 2.4604(10) A respectively],
the former a likely consequence of the less Lewis acidic boron
centre resulting from the p-donor diethylamido substituent as
described earlier. The angle between the platinum mean square
plane and the boron mean trigonal plane is 90.0◦ and that between
the adjacent boron and nitrogen trigonal planes is 6.0◦ (consistent
with the p-donor properties of the amido nitrogen). In all respects,
the structure of 8 is similar to that previously reported for the
dimethylamido analogue trans-[PtCl{BCl(NMe2)}(PPh3)2].17
X-ray crystallography. The results of the structure determination
are shown in Fig. 6 and reveal the expected trans geometry as
observed for related species including the chloro–B(cat) complex
trans-[PtCl{B(cat)}(PPh3)2].16 As shown in Scheme 2, complex 10
was formed in the reaction between [Pt(PMe3)4] and ClB(cat) and
also from the slow decomposition of cis-[Pt{B(cat)}2(PMe3)2] (11)
in dichloromethane over a period of months. Compound 11 (dB
1
49.4; dP −14.3, JPtP 1490 Hz) was prepared from the reaction
between [Pt(PMe3)4] and B2(cat)2, by analogy with other Pt(II) bis-
boryl species,1,16,17,22 and is structurally similar (Fig. 7) to all related
bis-phosphine, platinum(II) bis-boryl species.1,16,17,22
Treatment of either 1 (in the presence of excess NEt3)
or
8 with catechol afforded the B(cat) derivative trans-
[PtCl{B(cat)}(PMe3)2] (10) (Schemes 1 and 2) characterised spec-
troscopically (dB 33.3, 1JPtB 1039; dP −12.6, 1JPtP 2768 Hz) and by
Scheme 2
This journal is
The Royal Society of Chemistry 2007
Dalton Trans., 2007, 114–123 | 119
©

View Article Online
centre, consistent with the previous work of Braunschweig,12 and
a substitution chemistry of the B–Cl bond(s) which parallels the
chemistry observed by Roper for the related osmium BCl2 complex
described in the Introduction.8,9 The original report by No¨th
and Schmid of oxidative addition of BBr3 to Pt(0) resulting in a
BBr2 ligand is therefore consistent with these studies. In contrast,
however, we obtained no evidence for BCl3 adducts of platinum(0)
as described by Schram19 and later Wallbridge.20
Experimental
General procedures
All reactions were performed under dry dinitrogen using standard
Schlenk line techniques. Dry solvents were obtained from an
anhydrous engineering system and were degassed prior to use. All
reagents were procured commercially and used without further
purification except for [Pt(nbe)3]23 (nbe = norbornene = bicy-
clo[2.2.1]heptene) and B2(cat)224 which were prepared by literature
methods.
Fig. 6 A view of the molecular structure of compound 10. Se-
lected bond length (A) and angle (◦) data include: Pt(1)–B(1)
˚
1.995(6), Pt(1)–Cl(1) 2.4308(16), Pt(1)–P(1) 2.284(2), Pt(1)–P(2) 2.289(2),
B(1)–O(1) 1.423(7), B(1)–O(2) 1.415(7); Cl(1)–Pt(1)–B(1) 178.15(18),
P(1)–Pt(1)–P(2) 178.48(5), O(1)–B(1)–O(2) 108.8(5), Pt(1)–B(1)–O(1)
124.2(4), Pt(1)–B(1)–O(2) 127.0(4); interplanar angle 95.8.
Preparations
[PtCl(BCl2)(PMe3)2] (1). [Pt(nbe)3] (0.10 g. 0.21 mmol) was
dissolved in hexane (5 cm3), to which PMe3 (0.099 cm3, 0.84 mmol)
was added through a micro-syringe. The reaction mixture was
stirred for 1 h, and the solvent was removed in vacuo to give
a white solid. The solid was redissolved in toluene (10 cm3),
and BCl3 (0.84 cm3, 0.84 mmol, 1 M in heptane) was added at
−78 ◦C. The mixture was allowed to warm to room temperature,
and stirred for 1 h during which time a quantity of white precipitate
formed. After this time, all volatiles were removed in vacuo, and the
solid was redissolved in toluene (10 cm3) and filtered, affording a
colourless solution which was allowed to stand overnight resulting
in a further precipitate of the by-product, Me3PBCl3. The solvent
was removed slowly in vacuo, and the resulting solid redissolved
in toluene (5 cm3), and filtered to produce a solution of 1 from
which a white powder was obtained after further solvent removal
1
(0.096 g, 97%). Spectroscopic data for 1: NMR (C6D6) 11B{ H}
1
1
d 62.2 (1JPtB 1214 Hz), 31P{ H} d −14.6 (1JPtP 2635 Hz); H d
1.12 (m), 13C{ H} d 13.9 (t, 1JPC 20 Hz); mass spectrum (EI) 383
1
(M+ − BCl2). Attempts to crystallise 1 from this reaction mixture
were unsuccessful, resulting only in small quantities of the species
identified as [PtCl(PMe3)3][BCl4] by X-ray crystallography.
Fig. 7 A view of the molecul◦ar structure of compound 11. Selected
˚
bond length (A) and angle ( ) data include: Pt(1)–B(1) 2.061(10),
[PtCl(BCl2)(PPh3)2] (2). [Pt(nbe)3] (0.20 g. 0.42 mmol) and
PPh3 (0.22 g, 0.84 mmol) were dissolved in toluene (5 cm3) and
the reaction mixture stirred for 1 h, after which time the solvent
was removed in vacuo to give a white solid. This solid was then
dissolved in toluene (5 cm3), and BCl3 (0.42 cm3, 0.42 mmol, 1 M in
heptane) was added at −78 ◦C. The mixture was allowed to warm
to room temperature, and stirred for 1 h during which time a white
precipitate formed. All volatiles were then removed in vacuo, and
the resulting solid washed with toluene (3 × 1 cm3) (0.29 g, 81%).
Colourless crystals suitable for X-ray crystallography were formed
from solutions in toluene (1 cm3) and CH2Cl2 (1 cm3) layered with
Pt(1)–B(2) 2.032(9), Pt(1)–P(1) 2.331(2), Pt(1)–P(2) 2.327(2), B(1)–O(1)
1.413(12), B(1)–O(2) 1.388(14), B(2)–O(3) 1.415(11), B(2)–O(4) 1.413(11);
B(1)–Pt(1)–B(2) 82.2(2), P(1)–Pt(1)–P(2) 101.47(8), O(1)–B(1)–O(2)
108.1(7),
Pt(1)–B(1)–O(1)
126.7(7),
Pt(1)–B(1)–O(2)
124.6(7),
O(3)–B(2)–O(4) 107.8(7), Pt(1)–B(2)–O(3) 128.6(7), Pt(1)–B(2)–O(4)
123.5(6); interplanar angles 81.4 [B(1)], 91.5 [B(2)].
In conclusion, these studies have shown that platinum(II)
dichloroboryl complexes of the form trans-[PtCl(BCl2)(PR3)2] can
be formed in high yield from the oxidative addition of a B–Cl bond
in BCl3 to a platinum(0) centre in the presence of two equivalents of
a phosphine ligand. Furthermore, an examination of the reactivity
of such species, trans-[PtCl(BCl2)(PMe3)2] in particular, reveals
an adduct chemistry associated with the Lewis acidic boron
1
hexane. Spectroscopic data for 2: NMR (C6D6) 11B{ H} d 59 (br),
1
1
31P{ H} d 23.0 (1JPtP 3023 Hz), H d 7.66–7.73 (m), 7.33–7.41
1
(m), 13C{ H} d 140.0 (s), 134.9 (t, JPC 6.0), 130.6 (s), 128.3 (t,
120 | Dalton Trans., 2007, 114–123
This journal is
The Royal Society of Chemistry 2007
©

View Article Online
JPC 4.5); mass spectrum (EI) 754 (M+ − BCl2). Anal. Calcd for
excess of NEt3 (0.5 cm3) was then added. The mixture was stirred
C36H30BCl3P2Pt: H, 3.60; C, 51.65%. Found H, 3.70; C, 51.60%.
overnight affording a white precipitate of compound 6 (0.043 g,
1
36.9%). Spectroscopic data for 6: NMR (CD3CN) 11B{ H} d 27.8
1
(br), 31P{ H} d −13.0 (1JPtP 2643 Hz), 1H d 3.58–3.65 (q), 1.88 (t),
[PtCl(BCl2)(PMePh2)2] (3). [Pt(nbe)3] (0.10 g. 0.21 mmol) and
PMePh2 (0.080 cm3, 0.42 mmol) were dissolved in toluene (5 cm3)
and the reaction mixture was stirred for 1 h, after which time the
solvent was removed in vacuo to give an off-white oil. This oil was
then dissolved in toluene (5 cm3), and BCl3 (0.21 cm3, 0.21 mmol,
1 M in heptane) was added at −78 ◦C. The mixture was allowed to
warm to room temperature, and stirred for 1 h. All volatiles were
then removed in vacuo, and the resulting solid was redissolved
in toluene (3 cm3) and filtered. The filtrate was evaporated in
vacuo to give a white solid (0.085 g, 57%). Colourless crystals
suitable for X-ray crystallography were formed from solutions in
toluene (1 cm3) layered with hexane. Spectroscopic data for 3:
1.21 (br).
[PtCl{BCl2(py)}(PMe3)2] (7). A sample of compound 1
(0.10 g, 0.21 mmol) was dissolved in toluene (5 cm3) and the
solution was layered with an excess of pyridine (3 cm3). After
one week, a white precipitate of compound 7 was obtained
which was washed with hexane (3 × 2 cm3) (0.052 g, 46.5%).
1
Spectroscopic data for 7: NMR (CD3CN) 11B{ H} d 29.9 (1JPtB
1
957 Hz), 31P{ H} d −10.4 (1JPtP 2694 Hz). Both 6 and 7 are prone
to loss of the Lewis base bound to boron which prevented more
extensive spectroscopic and analytical characterisation.
1
1
NMR (C6D6) 11B{ H} d 61 (br), 31P{ H} d 7.6 (1JPtP 2890 Hz);
mass spectrum (EI) 631 (M+ − BCl2).
[PtCl{BCl(NEt2)}(PMe3)2] (8). A sample of compound 1
(0.10 g, 0.21 mmol) was dissolved in toluene (10 cm3), to which
HNEt2 (0.085 cm3, 0.84 mmol) was added. After stirring for 2 h,
the solution become cloudy and a white precipitate formed. The
solution was filtered and allowed to stand overnight affording a
precipitate of [NH2Me2]Cl. After filtration and removal of the
solvent, compound 8 was obtained as a white solid (0.095 g,
91.7%). Colourless crystals suitable for X-ray crystallography were
formed from solutions in toluene (0.5 cm3) layered with hexane.
[PtCl(BCl2)(PMe2Ph)2] (4). [Pt(nbe)3] (0.10 g. 0.21 mmol) and
PMe2Ph (0.061 cm3, 0.42 mmol) were dissolved in toluene (5 cm3)
and the reaction mixture stirred for 1 h, after which time the
solvent was removed in vacuo to give an off-white oil. This oil was
then dissolved in toluene (5 cm3), and BCl3 (0.21 cm3, 0.21 mmol,
1 M in heptane) was added at −78 ◦C. The mixture was allowed to
warm to room temperature, and stirred for 1 h. All volatiles were
then removed in vacuo, and the resulting solid was redissolved
in toluene (3 cm3) and filtered. The filtrate was evaporated in
vacuo to give a white solid (0.087 g, 74%). Colourless crystals
suitable for X-ray crystallography were formed from solutions in
toluene (1 cm3) layered with hexane. Spectroscopic data for 4:
1
Spectroscopic data for 8: NMR (C6D6) 11B{ H} d 35.9 (1JPtB
1
1028 Hz), 31P{ H} d −13.1 (1JPtP 2772 Hz), 1H d 3.41–3.35 (q, 2H);
3.24–3.19 (q, 2H,); 1.26 (t, 6H, 3JPtH 12.0, 2JPH 3.0 Hz); 0.95 (t, 3H);
1
0.88 (t, 3H), 13C{ H} d 47.5 (CH2, 3JPtC 70.4 Hz), 41.3 (CH2, 3JPtC
1
2
22.1 Hz), 14.7 (s, CH3), 14.5 (m, JPC 19.1, JPtC 38.2 Hz); mass
spectrum (EI) 465(M+ − Cl). Anal. Calcd for C10H28BCl2NP2Pt:
H, 5.65; C, 23.95%. Found H, 5.60; C, 24.00%.
1
1
NMR (C6D6) 11B{ H} d 61.8 (br), 31P{ H} d −6.7 (1JPtP 2731 Hz),
1H d 7.58–7.65 (m), 7.00–7.08 (m), 1.56 (t, 3JPtH 18.0, 2JPH 3.0 Hz),
13C{ H} d 131.3 (t, JPC 6.0), 130.1 (s), 128.4 (t, JPC 5.3), 13.3
1
(t, JPC 19.6); mass spectrum (EI) 507 (M+ − BCl2). Anal. Calcd
for C16H22BCl3P2Pt: H, 3.75; C, 32.65%. Found H, 3.85; C,
32.75%.
[PtCl{BCl(pip)}(PMe3)2] (9). A sample of compound 1
(0.10 g, 0.21 mmol) was dissolved in toluene (10 cm3), to which
piperidine (0.081 cm3, 0.84 mmol) was added. After stirring for 2 h,
the solution become cloudy and a white precipitate formed. The
solution was filtered and allowed to stand affording a precipitate of
[pipH2]Cl. After filtration and removal of the solvent, compound
9 was obtained as a white solid (0.083 g, 78.3%). Spectroscopic
[Pt2(BCl2)2(PMe3)4(l-Cl)][BCl4] (5). [Pt(nbe)3] (0.10 g.
0.21 mmol) was dissolved in hexane (5 cm3), to which PMe3
(0.055 cm3, 0.42 mmol) was added through a micro-syringe.
The reaction mixture was stirred for 1 h, and all the volatiles
were removed in vacuo to give an off-white oil. The solid was
redissolved in toluene (5 cm3), and an excess o◦f BCl3 (0.4 cm3,
0.46 mmol, 1 M in heptane) was added at −78 C. The mixture
was allowed to warm to room temperature, and stirred for 1 h
during which time a quantity of black oil formed. After this
time, all volatiles were removed in vacuo, and the solid was
redissolved in toluene (10 cm3) and filtered, affording a colourless
solution. The solvent was removed slowly in vacuo to give a white
powder (0.047 g, 43%). Colourless crystals suitable for X-ray
crystallography were formed from solutions in toluene (1 cm3)
layered with hexane. Spectroscopic data for 5: NMR (C6D6)
1
1
data for 9: NMR (C6D6) 11B{ H} d 34.3 (br), 31P{ H} d −9.9 (1JPtP
3000 Hz). Despite the similarity to compound 8, which has been
fully characterised, satisfactory analytical data were not obtained
for 9.
[PtCl{B(cat)}(PMe3)2] (10). A sample of compound 1 (0.10 g,
0.21 mmol) was dissolved in toluene (5 cm3), and an excess of
NEt3 (0.5 cm3) was added followed by a solution of catechol
(0.023 g, 0.21 mmol) in toluene (5 cm3). The mixture was stirred
for 2 h at room temperature affording compound 10 as a white
solid (0.076 g, 72%). Spectroscopic data for 10: NMR (CH3CN)
1
1
11B{ H} d 33.3 (1JPtB 1039 Hz), 31P{ H} d −12.6 (1JPtP 2768 Hz),
1
1
11B{ H} d 60.6 (1JPtB 1242 Hz), 11.1 (s), 31P{ H} d −14.7 (1JPtP
1H d 7.15–7.25 (m, C6H4), 6.85–6.90 (m, C6H4), 1.14 (m, CH3),
2628 Hz), 1H d 1.08 (t, 3JPtH 18.0, 2JPH 3.0 Hz), 13C{ H} d 14.0 (t,
1
1
13C{ H} d 149.9 (s, C6H4); 121.7 (s, C6H4); 111.4 (s, C6H4); 14.8
JPC 19.6 Hz); mass spectrum (EI) 383 (M+ − Pt(BCl2)2). Anal.
Calcd for C12H36B3Cl9P4Pt2: H, 3.45; C, 13.80%. Found H, 3.40;
C, 13.80%.
(t, CH3, JPC 20.1); mass spectrum (EI) 383 (M+ − Bcat). Anal.
1
Calcd for C12H22BClO2P2Pt: H, 4.40; C, 28.75%. Found H, 4.30; C,
28.70%. Compound 10 was also prepared, although not isolated,
by the following methods and identified spectroscopically (11B and
31P NMR).
[PtCl{BCl2(NEt3)}(PMe3)2] (6). A sample of compound 1
(0.10 g, 0.21 mmol) was dissolved in toluene (5 cm3), to which an
This journal is
The Royal Society of Chemistry 2007
Dalton Trans., 2007, 114–123 | 121
©

View Article Online
Method (i). A sample of compound 8 (0.10 g, 0.19 mmol)
was dissolved in toluene (5 cm3) to which a solution of catechol
(0.063 g, 0.57 mmol) in toluene (5 cm3) was added.
this crystal may be a racemic twin. Crystallographic data for all
compounds are presented in Table 1.
CCDC reference numbers 618539–618552.
For crystallographic data in CIF or other electronic format see
DOI: 10.1039/b612039n
Method (ii). A sample of compound 11 (0.11 g, 0.18 mmol) was
dissolved in CH2Cl2 (5 cm3) and the solution allowed to stand for
2 months. After this time, colourless crystals of 10 were obtained
by layered the solution with hexane.
Acknowledgements
Method (iii). A sample of [Pt(PMe3)4] (0.11 g, 0.21 mmol) was
dissolved in toluene (5 cm3) to which a solution of ClB(cat) (32 mg,
0.21 mmol) in toluene (5 cm3) was added.
We thank the EPSRC for support and the ORS Scheme for a
studentship (CF).
[Pt{B(cat)}2(PMe3)2] (11). A sample of [Pt(nbe)3] (0.10 g,
0.21 mmol) was dissolved in hexane (5 cm3), to which PMe3
(0.099 cm3, 0.84 mmol) was added through a micro-syringe. The
reaction mixture was stirred for 1 h at room temperature and the
solvent removed in vacuo affording a white solid. This solid was
dissolved in toluene (10 cm3), and B2(cat)2 (0.05 g, 0.21 mmol)
was added. The resulting mixture was stirred for 2 h at room
temperature to give white precipitate. The solvent volume to was
reduced to 1.5 cm3 in vacuo and the white precipitate was filtered
off, washed with toluene (2 cm3) and hexane (2 × 2 cm3) and
dried in vacuo (0.081 g, 65%). Colourless crystals suitable for X-
ray crystallography were formed from solutions in CH2Cl2 (1 cm3)
layered with hexane. Spectroscopic data for 11: NMR (CD2Cl2)
References
1 (a) S. Aldridge and D. L. Coombs, Coord. Chem. Rev., 2004, 248,
535; (b) H. Braunschweig and M. Colling, Coord. Chem. Rev., 2001,
223, 1; (c) H. Braunschweig, Angew. Chem., Int. Ed., 1998, 37, 1786;
(d) G. J. Irvine, M. J. G. Lesley, T. B. Marder, N. C. Norman, C. R.
Rice, E. G. Robins, W. R. Roper, G. R. Whittell and L. J. Wright,
Chem. Rev., 1998, 98, 2685; (e) H. Wadepohl, Angew. Chem., Int. Ed.
Engl., 1997, 36, 2441; (f) M. R. Smith III, Prog. Inorg. Chem., 1999, 48,
505.
2 For recent reviews on diboration, see: (a) T. B. Marder and N. C.
Norman, Top. Catal., 1998, 5, 63; (b) T. Ishiyama and N. Miyaura,
J. Synth. Org. Chem. Jpn., 1999, 57, 503; (c) T. Ishiyama and N.
Miyaura, J. Organomet. Chem., 2000, 611, 392; (d) T. Ishiyama and
N. Miyaura, Chem. Rec., 2004, 3, 271. For recent references on
C–H borylation see, for example:; T. Ishiyama and N. Miyaura,
J. Organomet. Chem., 2003, 680, 3; D. N. Coventry, A. S. Batsanov,
A. E. Goeta, J. A. K. Howard, T. B. Marder and R. N. Perutz, Chem.
Commun., 2005, 2172 and references therein.
1
1
1
11B{ H} d 49.4 (br), 31P{ H} d −14.3 (1JPtP 1490 Hz), H d 7.13–
7.07 (m, C6H4, 4H), 6.91–6.86 (m, C6H4, 4H), 1.50 (br, CH3, 18H),
1
13C{ H} d 149.9 (s, C6H4), 120.8 (s, C6H4), 111.4 (s, C6H4), 19.2
3 See: G. Schmid, Angew. Chem., Int. Ed. Engl., 1970, 9, 819 and
references therein.
4 G. Schmid, W. Petz, W. Arloth and H. No¨th, Angew. Chem., Int. Ed.
Engl., 1967, 6, 696.
5 G. Scmid, Chem. Ber., 1969, 102, 191.
(t, CH3, 1JPC 12.1); mass spectrum (EI) 346 (M+ − 2Bcat). Anal.
Calcd for C18H26B2O4P2Pt: H, 4.50; C, 36.95%, Found H, 4.40; C,
37.00%.
6 A. Kerr, T. B. Marder, N. C. Norman, A. G. Orpen, M. J. Quayle, C. R.
Rice, P. L. Timms and G. R. Whittell, Chem. Commun., 1998, 319; N.
Lu, N. C. Norman, A. G. Orpen, M. J. Quayle, P. L. Timms and G. R.
Whittell, J. Chem. Soc., Dalton Trans., 2000, 4032.
7 T. H. Peterson, J. T. Golden and R. G. Bergman, Organometallics, 1999,
18, 2005.
8 G. J. Irvine, C. E. F. Rickard, W. R. Roper, A. Williamson and L. J.
Wright, Angew. Chem., Int. Ed., 2000, 39, 948.
9 C. E. F. Rickard, W. R. Roper, A. Williamson and L. J. Wright,
Organometallics, 2002, 21, 1714; C. E. F. Rickard, W. R. Roper, A.
Williamson and L. J. Wright, Organometallics, 2002, 21, 4862; G. R.
Clark, G. J. Irvine, W. R. Roper and L. J. Wright, J. Organomet. Chem.,
2003, 680, 81.
X-Ray crystallography
Crystallographic data for compounds Ph3BCl3, PhMe2PBCl3, 3,
4 and Cl3BP(Ph)2CH2(Ph)2PBCl3, were collected at 173 K on a
Bruker-AXS SMART 1K diffractometer using Mo-Ka radiation
˚
(k = 0.71073 A). For compounds [Pt2(l-Cl)2(PMePh2)4][BCl4]2,
[Pt2Cl2(l-Cl)2(PCy3)2], 2 and 8, data were collected at 100 K
on a Bruker-AXS SMART Apex diffractometer equipped with
monocapillary beam focussing optics using Mo-Ka radiation
˚
(k = 0.71073 A). For compounds [PtCl(PMe3)3][BCl4], 10 and
10 S. Aldridge, R. J. Calder, R. E. Baghurst, M. E. Light and M. B.
Hursthouse, J. Organomet. Chem., 2002, 649, 9.
˚
11, data were collected using Cu-Ka radiation (k = 1.5418 A)
at 100 K on a Bruker-AXS Proteum diffractometer equipped
with a rotating anode source operated at 4.8 kW and Osmic
CMF12-38Cu6 (blue) mirror optics. For all compounds, intensity
data were collected as a series of frames, each of x width 0.3◦,
integrated25 and corrected for absorption26 and solved and refined
using routine techniques.27 The symmetrically unique anion in
complex [Pt2(l-Cl)2(PMePh2)4][BCl4]2 shows positional disorder
for three of its chlorine atoms. A sensible model for this disorder
was obtained by restraining the sets of Cl · · · Cl distances in each
of the disordered components to be equal and restraining the
displacement parameters of pairs of chlorine atoms opposite each
other with respect to the undisordered B(1)–Cl(2) axis to be equal.
Attempts to find a satisfactory model for the solvent present in
the structure of [Pt(PMe3)2(dppm)]Cl2 were unsuccessful and a
diffuse solvent correction was applied to the intensity data of this
compound using the SQUEEZE program of the Platon software
suite.28 The Flack parameter for [PtCl(PMe3)3][BCl4] indicates that
11 A. A. Dickinson, D. J. Willock, R. J. Calder and S. Aldridge,
Organometallics, 2002, 21, 1146.
12 H. Braunschweig, K. Radacki, F. Seeler and G. R. Whittell,
Organometallics, 2004, 23, 4178.
13 H. Braunschweig, K. Radacki, D. Rais and G. R. Whittell, Angew.
Chem., Int. Ed., 2005, 44, 1192.
14 H. Braunschweig, K. Radacki, D. Rais, F. Seeler and K. Uttinger,
J. Am. Chem. Soc., 2005, 127, 1386.
15 H. Braunschweig, K. Radacki, D. Scheschkewitz and G. R. Whittell,
Angew. Chem., Int. Ed., 2005, 44, 1658.
16 W. Clegg, F. J. Lawlor, G. Lesley, T. B. Marder, N. C. Norman, A. G.
Orpen, M. J. Quayle, C. R. Rice, A. J. Scott and F. E. S. Souza,
J. Organomet. Chem., 1998, 550, 183.
17 D. Curtis, M. J. G. Lesley, N. C. Norman, A. G. Orpen and J. Starbuck,
J. Chem. Soc., Dalton Trans., 1999, 1687.
18 H. Braunschweig, K. Radacki, D. Rais and F. Seeler, Organometallics,
2004, 23, 5545.
19 T. R. Durkin and E. P. Schram, Inorg. Chem., 1972, 11, 1054.
20 M. Fishwick, H. No¨th, W. Petz and M. G. H. Wallbridge, Inorg. Chem.,
1976, 15, 490.
21 J. Zhu, Z. Lin and T. B. Marder, Inorg. Chem., 2005, 44, 9384.
122 | Dalton Trans., 2007, 114–123
This journal is
The Royal Society of Chemistry 2007
©

View Article Online
22 G. Lesley, P. Nguyen, N. J. Taylor, T. B. Marder, A. J. Scott, W. Clegg
and N. C. Norman, Organometallics, 1996, 15, 5137.
Inorg. Chem., 1998, 37, 5289; M. J. G. Lesley, N. C. Norman and C. R.
Rice, Inorg. Synth., 2004, 34, 1.
25 SAINT integration software, Bruker-AXS Inc., Madison, WI, 2004.
26 G. M. Sheldrick, SADABS absorption correction program, University
of Go¨ttingen, Germany, 2003.
23 L. E. Crascall and J. L. Spencer, Inorg. Synth., 1990, 28, 127.
24 C. N. Welch and S. G. Shore, Inorg. Chem., 1968, 7, 225; R. J. Brotherton
and W. G. Woods, US Patent, 3 009 941, 1961; F. J. Lawlor, N. C.
Norman, N. L. Pickett, E. G. Robins, P. Nguyen, G. Lesley, T. B.
Marder, J. A. Ashmore and J. C. Green, Inorg. Chem., 1998, 37, 5282;
W. Clegg, M. R. J. Elsegood, F. J. Lawlor, N. C. Norman, N. L. Pickett,
E. G. Robins, A. J. Scott, P. Nguyen, N. J. Taylor and T. B. Marder,
27 SHELXTL program system, Bruker-AXS Inc., Madison, WI,
2003.
28 A. L. Spek. PLATON, A Multipurpose Crystallographic Tool, Utrecht
University, Utrecht, The Netherlands, 2005.
This journal is
The Royal Society of Chemistry 2007
Dalton Trans., 2007, 114–123 | 123
©