Synthesis, characterization and structural studies of new heterometallic alkynyl complexes of platinum and Group 11 metals with chelating bis(diphenylphosphino)ferrocene ligand

Article abstract of DOI:10.1016/S0022-328X(02)01710-2

Reaction of the platinum bis(alkynyl) complex [Pt(dppf)(C ≡ CPh)₂] (1) (dppf = bis(diphenylphosphino)ferrocene) with an equimolar amount of Group 11 metal salts [Cu(NCMe)₄]BF₄ and AgBF₄ initially gives 1:1 mixed

Full text of DOI:10.1016/S0022-328X(02)01710-2

Journal of Organometallic Chemistry 659 (2002) 107ꢂ116
/
www.elsevier.com/locate/jorganchem
Synthesis, characterization and structural studies of new
heterometallic alkynyl complexes of platinum and Group 11 metals
with chelating bis(diphenylphosphino)ferrocene ligand
Wai-Yeung Wong *, Guo-Liang Lu, Ka-Ho Choi
Department of Chemistry, Hong Kong Baptist University, Waterloo Road, Kowloon Tong, Hong Kong, PR China
Received 13 May 2002; received in revised form 1 July 2002; accepted 3 July 2002
Abstract
Reaction of the platinum bis(alkynyl) complex [Pt(dppf)(Cꢀ
equimolar amount of Group 11 metal salts [Cu(NCMe)4]BF4 and AgBF4 initially gives 1:1 mixed-metal complexes [Pt(dppf)(Cꢀ
CPh)2Cu(NCMe)]BF4 (2) and [Pt(dppf)(CꢀCPh)2Ag]BF4 (3) in good yields. Upon standing in solution at room temperature,
compounds 2 and 3 rearrange and aggregate to the corresponding diplatinum complexes [{Pt(dppf)(CꢀCPh)2}2M]BF4 (MꢀCu (4),
/
CPh)2] (1) (dppfꢀ/bis(diphenylphosphino)ferrocene) with an
/
/
/
/
Ag (5)) which exhibit an intense molecular ion envelope for the respective cation in their electrospray mass spectra. Compounds 4
and 5 can also be formed when the reaction is performed using a 2:1 molar ratio of 1 and the Group 11 salts. The X-ray crystal
structures of 1, 4 and 5 have been determined. Structures of 4 and 5 reveal that the two square-planar platinum coordination planes
in the cation are approximately orthogonal an 2-fashion to four carbonꢁ
/
carbon triple bonds to afford heterometallic
pentanuclear Fe2Pt2M complexes (MꢀCu, Ag) in which each platinum center is stabilized by a dppf ligand. Each of the new
/
complexes displays a reversible oxidation couple corresponding to the ferrocenyl unit of dppf and there is less stabilization of the
silver in the mixed-metal complex than in the copper congeners. # 2002 Elsevier Science B.V. All rights reserved.
Keywords: Copper; Silver; Platinum; Ferrocene; Crystal structures
1. Introduction
as organometallic chelating ligands in the formation of
novel homo- or hetero-bimetallic molecules, where the
second metal is bonded in an h2-fashion to the alkynyl
The molecular design and synthesis of polynuclear
acetylide systems continue to attract considerable cur-
rent interest because of the unusual structural features
and the novel reactivity patterns exhibited by these
molecules [1]. In particular, the reaction chemistry of
Cꢀ
/C triple bonds [1a,3]. In this context, the most widely
investigated complexes are mainly based either upon the
bis(cyclopentadienyl)titanium system [1a,2a,2b,2d], or
upon cis-platinum systems with imines, tertiary phos-
phines or C6F5 entity as the auxiliary groups [1a,2e].
These bimetallic complexes have been shown to display
interesting chemical and physical properties. Although
bis(alkynyl) metal complexes R1ꢁ
/
Cꢀ
/
Cꢁ
/
[M]ꢁ
/
Cꢀ
/
Cꢁ
/
R2
towards different transition metal centers (electron-rich
or -deficient) species has been extensively studied [1a,2].
A vast range of coordination modes of the alkynyl
ligands are found in these systems which depend on the
nature of the alkynyl substituents, the auxiliary ligands
and the metal centers involved [1a,3]. Among these,
tweezer-type transition metal bis(alkynyl) precursor
complexes in a cis configuration are widely exploited
there are numerous reports on the use of cis-[PtL2(Cꢀ
CR)2] precursors (LꢀPPh3, L2ꢀdppe, bipy, substi-
tuted bipy; RꢀSiMe3, Ph, Bu, etc.) to form tweezer-
/
/
/
t
/
like complexes [1a,2], organometallic chelating ligands
such as bis(diphenylphosphino)ferrocene (dppf) are, to
our knowledge, rarely employed in such study. Dppf
ligand is expected to impart strikingly different proper-
ties to these systems from the purely organic moieties or
metal-free phosphine groups, particularly with respect
to their spectroscopic and redox behavior [4].
* Corresponding author. Tel.: ꢁ
7348
E-mail address: rwywong@hkbu.edu.hk (W.-Y. Wong).
/
852-3411-7074; fax: ꢁ852-3411-
/
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 7 1 0 - 2

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W.-Y. Wong et al. / Journal of Organometallic Chemistry 659 (2002) 107ꢂ116
/
Recently, we have reported the preparation of two
novel heterotetranuclear carbonyl clusters [Os3Pt-
Lꢀ4,4?-
dimethyl-2,2?-bipyridine, 4,4?-bis(tert-butyl)-2,2?-bipyri-
dine) from the reactions of [Os3(CO)10(NCMe)2] with
catalyzed chloride-to-alkyne metathesis reaction be-
tween [Pt(dppf)Cl2] and PhCꢀCH in the CuIꢂamine
system [7]. An improved synthesis leading to
[Pt(dppf)Cl2] [8] was employed which involves treatment
of [PtCl2(SEt2)2] [9] with dppf in CH2Cl2 at room
temperature. The yield and purity of 1 is similar to
that reported by Dias and coworkers [10]. The 1:1
/
/
(CO)9(m4-h2-Cꢀ
/
CPh)(h1-Cꢀ
/
CPh)(Lꢁ
/
L)] (Lꢁ
/
/
the molecular tweezers [Pt(Lꢁ
/
L)(Cꢀ/CPh)2] [5]. In line
with our efforts to develop other assembled multi-
metallic systems involving platinum bis(alkynyl) com-
plexes [6], we utilize the dppf-stabilized complex
trimetallic
Me)]BF4 (2) and [Pt(dppf)(Cꢀ
complexes
[Pt(dppf)(Cꢀ
/
CPh)2Cu(NC-
/
CPh)2Ag]BF4 (3) were
[Pt(dppf)(Cꢀ
/
CPh)2] (1) as a starting precursor for the
synthesized in almost quantitative yields by the room
temperature reaction of the platinum bis(alkynyl) pre-
cursor 1 in chloroform with a stoichiometric amount of
[Cu(NCMe)4]BF4 and AgBF4, respectively, in acetoni-
trile. Pure 2 and 3 are stable as solids, but are prone to
undergo rearrangement reactions after prolonged peri-
ods in solutions. Upon standing in solutions, com-
pounds 2 and 3 rearrange to the corresponding 2:1
encapsulation of low-valent Group 11 transition metals,
which may provide synthetic access to some multi-
metallic compounds. The chelating dppf ligand was
chosen due to its large steric strain in square-planar Pt
complexes, which ensures a cis configuration. We
describe here the reactions of 1 with some Group 11
metal salts [Cu(NCMe)4]BF4 and AgBF4 and the
structural characterizations of new mixed-metal penta-
mixed-metal pentanuclear aggregates [{Pt(dppf)(Cꢀ
/
nuclear Fe2Pt2M complexes [{Pt(dppf)(Cꢀ
/
CPh)2}2-
CPh)2}2M]BF4 (MꢀCu (4), Ag (5)). Similar treatment
/
M]BF4 (MꢀCu, Ag) are described.
/
of 1 with 0.5 equivalent of Group 11 metal salts in the
same solvent combination led to the isolation of 4 and 5
in high purity and yields. New complexes 2ꢂ5 are
/
2. Results and discussion
soluble in common organic solvents and have been
characterized by satisfactory microanalysis, IR and
NMR spectroscopies (Section 4). The identities of 2
and 3 were also supported by fast atom bombardment
mass spectrometry (FAB-MS) and 4 and 5 by electro-
spray ionization mass spectrometry (ESI-MS). The
molecular structures of 1, 4 and 5 have been established
by X-ray crystallography (vide infra).
2.1. Synthesis and spectroscopic characterization
The results of the reactions are summarized in Scheme
1. In accordance with the synthetic strategy for making
the
complexes
[Pt(diimine)(Cꢀ
/CAr)2],
complex
CPh)2] (1) is readily prepared by a CuI-
[Pt(dppf)(Cꢀ
/
Scheme 1. (i)
1
equivalent [Cu(NCMe)4]BF4 or AgBF4, CHCl3 ꢂ
/
MeCN. (ii) CH2Cl2 ꢂhexane, room temperature. (iii) 0.5 equivalent
/
[Cu(NCMe)4]BF4 or AgBF4, CHCl3 ꢂ
/MeCN.

W.-Y. Wong et al. / Journal of Organometallic Chemistry 659 (2002) 107ꢂ
/116
109
In the solid state IR spectra, complex 1 shows two Cꢀ
/
scheme. Pertinent interatomic distances and angles are
C stretching vibrations at ca. 2112 and 2120 cmꢃ1
whereas compounds 3 and 5 display a very weak nCꢀC
absorption at the lower wavenumber region than 1
because of the h2-coordination of the alkyne at the silver
atom [1a]. However, we cannot observe the correspond-
ing peaks for the copper analogues. The 1H-NMR
given in Table 1. The structure of 1 affirms the proposed
geometry of the compound in which the platinum center
is square-planar with two phenylethynyl groups bonded
in a cis arrangement, as imposed by the presence of the
chelating dppf ligand. The Ptꢁ
/
P distances compare well
with that found in [Pt(dppf)(tba)] (tbaꢀ
/
tolan-2,2?-
spectra of diamagnetic compounds 2ꢂ
/
5 consist of well-
diacetylide) [12]. To our knowledge, there are only a
few structurally characterized examples of transition
resolved signals for each of the organic and ferrocenyl
groupings present. Their spectroscopic data show close
resemblance to those found in the parent complex 1,
although small differences in chemical shifts are ob-
served. The sharp singlet peak at d 1.97 for 2 is due to
the coordinated acetonitrile molecule, in agreement with
the monomeric structure of 2 in solution initially. The
retention of the phosphines is evident from the 31P-
NMR spectrum in each case, which shows a strong
singlet flanked by two platinum satellites, and the values
metal alkynyl complexes of the type cis-[Pt(Lꢁ
CR)2] (LꢁLꢀmono- or bidentate phosphines) in the
literature [7b,12,13]. The alkynyl bond distances range
/
L)(Cꢀ
/
/
/
˚
from 1.195(2) to 1.199(2) A, typical of other related
complexes [7b,12,13]. The cyclopentadienyl rings of the
ferrocenyl group are essentially planar with a tilt angle
of 3.58. An eclipsed nature of the C5 rings in the
structure of 1 is confirmed with deviation angle of ca.
2.48.
Chart1
1
of JPtꢁP (2506ꢂ
/
2648 Hz) are consistent with a cis
X-Ray crystallographic analysis on 4 reveals that the
structure contains the cationic pentanuclear unit
configuration for the phosphines and for the acetylides
about platinum [7b,10,11]. The FAB-MS data for 3 and
[{Pt(dppf)(Cꢀ
/
CPh)2}2Cu]ꢁ and a drawing of the cation
is illustrated in Fig. 4 along with selected bond para-
meters shown in Table 2. The cation is formed by two
4 showed peaks corresponding to the [Mꢃ
/
MeCNꢁ
/
BF4]ꢁ and [MꢃBF4]ꢁ fragments, respectively. The
/
formulae of the larger complexes 4 and 5 were studied
by the electrospray mass spectrometric technique with
methanol as the mobile phase. The ESI-MS spectra of 4
and 5 exhibited an intense parent peak for the cation at
m/z 1966 and 2011, respectively, which match very well
with the calculated isotopic distribution patterns (Figs. 1
and 2). The soft ionization mode in ESI-MS reduces the
degree of fragmentation as compared with other com-
mon ionization methods (e.g. EI or FAB), which can
maximize the population of target species to enter the
ion trap.
nearly orthogonal Pt(dppf)(Cꢀ
/
CPh)2 units (the dihedral
angle between the best-squares coordination planes
PtP2C2 being 85.98) bridged by a monomeric copper
ion. Each of the two Pt(dppf)(Cꢀ
an essentially square-planar platinum center and be-
haves as a bidentate chelating ligand for the copper
entity. The geometric details of the two Pt(dppf)
/
CPh)2 units possesses
moieties in 4 are similar to those reported for 1. The
˚
P distances vary from 2.300(2) to 2.323(2) A and the
C distances are in the expected range quoted in the
Ptꢁ
/
Ptꢁ
/
literature for s-alkynylplatinum compounds [7b,12,13].
The central metal atom adopts an approximately tetra-
hedral arrangement and is h2-coordinated to four
alkyne groups with slightly shorter distances to the b-
carbon than to the a-carbon atoms of the ethynyl
2.2. Crystal structure analyses
Single-crystal X-ray analyses were carried out for 1, 4
and 5 to ascertain their solid-state structures (Chart 1).
A perspective view of the molecular structure of 1 is
depicted in Fig. 3, which includes the atom-numbering
groups (mean a-distances 2.228(7), b-distances 2.350(7)
˚
A) [1a]. These Cuꢁ
/
C(alkyne) distances are comparable
to those found in [{Pt(dppe)(Cꢀ
/CPh)2}2Cu]BF4

110
W.-Y. Wong et al. / Journal of Organometallic Chemistry 659 (2002) 107ꢂ116
/
Fig. 1. The ESI mass spectrum of 4 recorded in MeOH. The inset shows the simulated isotopic mass pattern.
Fig. 2. The ESI mass spectrum of 5 recorded in MeOH. The inset shows the simulated isotopic mass pattern.

W.-Y. Wong et al. / Journal of Organometallic Chemistry 659 (2002) 107ꢂ
/116
111
Fig. 3. Molecular structure of 1, showing the atomic labelling scheme. Labels on the phenyl rings and all hydrogen atoms have been omitted for
clarity.
mixed copperꢂplatinum complex was indicated from the
/
Table 1
˚
˚
Pt(1)Á Á ÁCu (3.171 A) and Pt(2)Á Á ÁCu (3.217 A) distances,
reminiscent of other similar compounds [1a,2e,14]. As
far as the phosphinoferrocenyl groups are concerned,
˚
Selected bond lengths (A) and angles (8) for compound 1×C4H8O
Bond lengths
Pt(1)ꢁP(1)
Pt(1)ꢁC(1)
C(1)ꢁC(2)
2.3109(4)
2.0045(16)
1.195(2)
Pt(1)ꢁP(2)
Pt(1)ꢁC(9)
C(9)ꢁC(10)
2.3008(4)
1.9943(15)
1.199(2)
the cyclopentadienyl rings of each ferrocenyl unit are
˚
almost planar (mean deviation of ca. 0.0035ꢂ0.0061 A)
and the tilt angle is 3.18 in each case. The C5H4
fragments of the ferrocenyl group deviate from the
staggered configuration by 1.4 and 2.78 for the Fe(1)
/
Bond angles
P(1)ꢁPt(1)ꢁP(2)
Pt(1)ꢁC(1)ꢁC(2)
C(1)ꢁC(2)ꢁC(3)
100.025(14) C(1)ꢁPt(1)ꢁC(9)
173.20(14)
88.48(7)
176.66(16)
177.4(2)
Pt(1)ꢁC(9)ꢁC(10)
176.331(18) C(9)ꢁC(10)ꢁC(11)
and Fe(2) units, respectively. The mean Feꢁ
/
C(C5H4)
bond length is 2.028 A and the C5H4 rings produce an
˚
˚
average distance of 1.6257 and 1.6379 A from their
centroids to Fe(1) and Fe(2), respectively.
˚
˚
(2.19(3)ꢂ
of the Pt(1)ꢁ
Pt(2)ꢁP(3)ꢁP(4) plane. The geometries of the Pt(Cꢀ
CPh)Cu bridges are normal and similar to those in
CR)2M]X
/
2.49(3) A) [14]. The Cu atom lies 0.2145 A out
˚
/
P(1)ꢁ
/
P(2) plane and 0.3179 A out of the
A partial determination of the molecular structure of
5 was made; the cation of which is depicted in Fig. 5.
Preliminary X-ray study is consistent with the proposed
structure but the poor quality of the data as well as the
severe disorder problem encountered for the anion
precludes discussion of the structural details. Generally
speaking, the structure of 5 is very similar to that of 4,
except that Cu(I) is being replaced by Ag(I) and the
structural parameters are rather close to those observed
/
/
/
derivatives of the general type [Pt(Lꢁ
/
L)(Cꢀ
/
(LꢁLꢀ
/
/
diimines, mono- or bidentate phosphines; Rꢀ
/
SiMe3, Ph, tBu; Mꢀ
/
Cu, Cu(NCMe); Xꢀ
/
Cl, SCN,
BF4, ClO4, etc.) [1a,2e,14]. As a result of the h2-
coordination of each alkynyl ligand in 4 to the Cu
center, we note a bending of the Cꢀ
176.3(2)ꢂ177.4(2)8 in 1 to 167.5(8)ꢂ173.1(8)8 in 4. The
bite angle CaꢁPtꢁCa? also decreases slightly from
88.48(7)8 in 1 to the mean value of ca. 87.1(3)8 in 4
[1a]. The absence of metalꢂmetal interactions in this
/
Cꢁ
/
Ph units from
/
/
for [{Pt(PPh3)2(Cꢀ
/
CPh)4}Ag]ClO4 [15]. Again, the in-
/
/
tramolecular contacts between Pt and Ag atoms in 5 (ꢀ
/
˚
3.3 A) are well outside the range for any direct metalꢂ
/
/
metal interactions.

112
W.-Y. Wong et al. / Journal of Organometallic Chemistry 659 (2002) 107ꢂ116
/
Fig. 4. Molecular structure of the cation of 4, showing the atomic labelling scheme. Labels on the phenyl rings and all hydrogen atoms have been
omitted for clarity.
the single-step two-electron oxidation involving the
concomitant oxidation of the two terminal ferrocenyl
Table 2
˚
Selected bond lengths (A) and angles (8) for compound 4
groups [6a,16]. The possibility that this oxidation event
MII couple can be ruled out since the
is due to the MI0
/
Bond lengths
Pt(1)ꢁP(1)
Pt(2)ꢁP(3)
Pt(1)ꢁC(35)
Pt(2)ꢁC(85)
CuꢁC(35)
CuꢁC(43)
CuꢁC(85)
CuꢁC(93)
C(35)ꢁC(36)
C(85)ꢁC(86)
2.300(2)
Pt(1)ꢁP(2)
2.323(2)
2.3223(19)
2.012(8)
2.014(7)
2.336(7)
2.415(7)
2.350(8)
2.300(7)
1.186(9)
1.209(8)
oxidized M(II) species (MꢀCu, Ag) does not favour co-
/
2.3018(19) Pt(2)ꢁP(4)
ordination by the acetylide bridges, making the process
irreversible [2e]. An anodic shift of the ferrocene-
ferrocenium couple in 1 with reference to [Pt(dppf)Cl2]
is consistent with the unsaturation of the ethynyl group
which makes the removal of electrons more difficult.
Upon complexation with Group 11 metal ions, the
ferrocenyl redox potential shows a negative shift of ca.
2.025(8)
2.021(9)
2.227(7)
2.242(6)
2.247(7)
2.196(7)
1.194(8)
1.206(9)
Pt(1)ꢁC(43)
Pt(2)ꢁC(93)
CuꢁC(36)
CuꢁC(44)
CuꢁC(86)
CuꢁC(94)
C(43)ꢁC(44)
C(93)ꢁC(94)
0.20ꢂ0.26 V which is in line with the stronger electron
/
Bond angles
donation from the ferrocenyl moiety to stabilize the
positive charge on the M(I) ion. With each Group 11
metal, there is only a small difference in the potential
values between the 1:1 and 2:1 mixed-metal complexes.
The higher oxidation potentials for the silver complexes
than for the copper counterparts suggest that there
should be less stabilization of the silver in the complexes
than in the copper complexes [2e]. Another redox event
P(1)ꢁPt(1)ꢁP(2)
C(35)ꢁPt(1)ꢁC(43)
Pt(1)ꢁC(35)ꢁC(36)
Pt(2)ꢁC(85)ꢁC(86)
C(35)ꢁC(36)ꢁC(37) 169.3(8)
C(85)ꢁC(86)ꢁC(87) 169.1(8)
97.63(7)
88.4(3)
P(3)ꢁPt(2)ꢁP(4)
98.23(7)
85.8(3)
C(85)ꢁPt(2)ꢁC(93)
Pt(1)ꢁC(43)ꢁC(44)
Pt(2)ꢁC(93)ꢁC(94)
C(43)ꢁC(44)ꢁC(45) 173.1(8)
C(93)ꢁC(94)ꢁC(95) 167.5(8)
Pt(1)ꢁC(43)ꢁCu
Pt(2)ꢁC(93)ꢁCu
172.8(7)
175.7(7)
178.3(7)
178.7(6)
Pt(1)ꢁC(35)ꢁCu
Pt(2)ꢁC(85)ꢁCu
96.7(3)
97.7(3)
96.6(3)
99.5(3)
was also observed at ꢁ
to the PtII0PtIII irreversible oxidation. However, no
such anodic wave was associated with the mixed-metal
compounds 2ꢂ5.
/
0.52 V for 1 which is attributable
/
2.3. Electrochemistry
/
The electrochemical properties of our new complexes
were investigated by cyclic voltammetry in CH2Cl2 at
room temperature (r.t.) and the redox data are gathered
in Table 3. In each case, the cyclic voltammogram is
characterized by a single quasi-reversible oxidation wave
due to the ferrocenyl electrophore that is present in the
complex. The oxidation wave for 4 and 5 corresponds to
3. Concluding remarks
This report demonstrates the successful use of dppf-
stabilized platinum bis(alkynyl) precursor 1 as bidentate
complexing agents for the stabilization of low oxidation

W.-Y. Wong et al. / Journal of Organometallic Chemistry 659 (2002) 107ꢂ
/116
113
Fig. 5. Molecular structure of the cation of 5, showing the atomic labelling scheme. Labels on the phenyl rings and all hydrogen atoms have been
omitted for clarity.
4. Experimental
Table 3
Redox data for the dppf-stabilized platinum bis(alkynyl) complexes in
CH2Cl2
4.1. General procedures
a
Complex
E1/2 (V)
All reactions were carried out under N2 with the use
of standard inert atmosphere and Schlenk techniques,
but no special precautions were taken to exclude oxygen
during work-up. Solvents were predried and distilled
from appropriate drying agents [17]. All chemicals,
unless otherwise stated, were obtained from commercial
sources and used as received. The compound [Cu(NC-
Me)4]BF4 was prepared according to the published
literature method [18]. Infrared spectra were recorded
[Pt(dppf)Cl2]
0.60 (99)
0.52 b, 0.83 (138)
0.60 (99)
1
2
3
4
5
0.63 (99)
0.57 (99)
0.59 (119)
a
Scan rateꢀ100 mV sꢃ1
,
half-wave potential values
E1/2ꢀ(EpaꢁEpc)/2 for reversible oxidation, DEpꢀEpaꢃEpc (in mV)
for reversible waves are given in parentheses, where Epa and Epc are the
anodic and cathodic peak potentials, respectively.
as KBr pellets on a PerkinꢂElmer Paragon 1000 PC or
/
b
Irreversible wave.
Nicolet Magna 550 Series II FTIR spectrometer. NMR
spectra were measured in CDCl3 on a JEOL EX270 or a
1
Varian INOVA 400 MHz FT NMR spectrometer. H-
NMR chemical shifts were quoted relative to SiMe4
(dꢀ
0) and 31P chemical shifts relative to an 85% H3PO4
state Group 11 metal moieties. Starting with 1, some
new 1:1 and 2:1 mixed-metal complexes of platinum and
Group 11 metals bridged by alkynyl ligands in an h2-
manner were prepared and spectroscopically character-
ized. Even in the presence of bulky dppf ligands,
aggregation into the larger 2:1 species is possible
and positive-mode electrospray mass spectrometric and
X-ray crystal structure analyses unequivocally establish
/
external standard. Positive FAB mass spectra were
recorded on a Finnigan MAT SSQ710 mass spectro-
meter. The ESI mass spectrometry experiments were
performed on a PE SCIEX API QSTAR PULSAR i
mass spectrometer. Mass spectra of compounds 4 and 5
were acquired in the positive-ion detection mode using
methanol as the mobile phase and the sample was
injected at the rate of 10 ml minꢃ1. The ion spray voltage
of the ESI source was set at 5.5 kV. Electronic
absorption spectra were obtained with a Hewlett Pack-
the identity of the complexes [{Pt(dppf)(Cꢀ
CPh)2}2M]BF4 (MꢀCu (4), Ag (5)) to be a 2:1 Pt/M
stoichiometry.
/
/

114
W.-Y. Wong et al. / Journal of Organometallic Chemistry 659 (2002) 107ꢂ116
/
ard 8453 UVꢂ
/
vis spectrometer. Cyclic voltammetry
4.2.3. Synthesis of [Pt(dppf)(Cꢀ
CPh)2Cu(NCMe)]BF4 (2) and [{Pt(dppf)(Cꢀ
CPh)2}2Cu]BF4 (4)
To a solution of [Pt(dppf)(Cꢀ
/
experiments were done with a Princeton Applied Re-
search (PAR) model 273A potentiostat. A conventional
three-electrode configuration consisting of a glassy-
carbon working electrode, a Pt-wire counter electrode
and a Ag/AgNO3 reference electrode (0.1 M in MeCN)
was used. The solvent in all measurements was deox-
ygenated CH2Cl2 and the supporting electrolyte was 0.1
M [Bu4N]PF6. Ferrocene was added as a calibrant after
each set of measurements and all potentials reported
/
/
CPh)2] (9.5 mg, 0.01
mmol) in CHCl3 (5 ml) was added a solution of
[Cu(NCMe)4]BF4 (3.5 mg, 0.01 mmol) in MeCN (1
ml). After the mixture was stirred for 1 h at r.t., all the
volatile components were removed under reduced pres-
sure. The residue was taken up in CHCl3 and filtered.
Removal of the solvents gave 2 as a bright yellow solid
were quoted with reference to the ferroceneꢂ
/ferroce-
1
in almost quantitative yield (98%, 11.2 mg). H-NMR
(CDCl3): d 1.97 (s, 3H, MeCN), 4.23 (s, 4H, C5H4), 4.45
nium couple. The number of electrons transferred for 4
and 5 was estimated by comparing the peak height of the
respective ferrocene oxidation wave with an equal
concentration of the ferrocene standard added in the
same system, in which one-electron oxidation was
assumed.
(s, 4H, C5H4), 6.66ꢂ
(m, 6H, CꢀCPh), 7.32ꢂ
8H, Ph). 31P{1H}-NMR (CDCl3): d 14.12 (1JPtꢁP
Hz). FAB-MS (m/z): 1015 [MꢃMeCNꢁ
BF4]ꢁ. Anal.
/
6.69 (m, 4H, Cꢀ
/
CPh), 7.07ꢂ
7.76 (m,
2646
/7.12
/
/
7.45 (m, 12H, Ph), 7.69ꢂ
/
ꢀ
/
/
/
Found: C, 54.50; H, 3.42; N, 1.04. C52H41NBCuF4-
FeP2Pt requires C, 54.64; H, 3.62; N, 1.23%. A solution
of compound 2 in a mixture of CH2Cl2 and C6H14 was
slowly evaporated at r.t., leading to a deposit of lemon-
4.2. Complex preparations
1
4.2.1. Synthesis of [Pt(dppf)Cl2]
yellow crystals of 4 after 1 day (yield 80%). H-NMR
This compound was prepared by a modification of the
literature method [8]. To a suspension of PtCl2 (266.0
mg, 1.00 mol) in CH2Cl2 (10 ml), SEt2 (0.32 ml, 3.00
mmol) was added to give a clear yellow solution of
[PtCl2(SEt2)2]. After the solution was stirred for 0.5 h,
dppf (555.0 mg, 1.00 mmol) was added and the resulting
brown solution was stirred for an additional 0.5 h. The
solvent was then removed under reduced pressure and
the residue washed with a mixture of CH2Cl2 and C6H14
(1:1, v/v) to afford a yellow powder of [Pt(dppf)Cl2]
(96%, 788.0 mg). 1H-NMR (CDCl3): d 4.18 (s, 4H,
(CDCl3): d 3.97 (s, 8H, C5H4), 4.35 (s, 8H, C5H4), 6.91ꢂ
6.93 (m, 8H, CꢀCPh), 7.11ꢂ7.17 (m, 12H, CꢀCPh),
7.22ꢂ7.36 (m, 24H, Ph), 7.43ꢂ7.48 (m, 16H, Ph).
31P{1H}-NMR (CDCl3): d 14.27 (1JPtꢁP
2559 Hz).
ESI-MS (m/z): 1966 [Mꢃ
BF4]ꢁ. Anal. Found: C,
/
/
/
/
/
/
ꢀ
/
/
58.26; H, 3.58. C100H76BCuF4Fe2P4Pt2 requires C,
58.48; H, 3.73%.
4.2.4. Synthesis of [Pt(dppf)(Cꢀ
[{Pt(dppf)(CꢀCPh)2}2Ag]BF4 (5)
/
CPh)2Ag]BF4 (3) and
/
C5H4), 4.36 (s, 4H, C5H4), 7.34ꢂ
7.82ꢂ
7.89 (m, 8H, Ph). 31P{1H}-NMR (CDCl3): d 14.54
(1JPtꢁP 3755 Hz). FAB-MS (m/z): 820 [M]ꢁ. Anal.
/
7.49 (m, 12H, Ph),
Complex 3 was prepared using the same conditions
described above for 2, but AgBF4 (2.2 mg, 0.01 mmol)
was used instead to produce a bright yellow solid of 3 in
96% yield (11.0 mg). IR (KBr, cmꢃ1): 2075vw (nCꢀC).
1H-NMR (CDCl3): d 4.22 (s, 4H, C5H4), 4.43 (s, 4H,
/
ꢀ
/
Found: C, 49.60; H, 3.11. C34H28Cl2FeP2Pt requires C,
49.78; H, 3.44%.
C5H4), 6.89ꢂ
CꢀCPh), 7.34ꢂ
Ph). 31P{1H}-NMR (CDCl3): d 12.93 (1JPtꢁP
Hz). FAB-MS (m/z): 1059 [Mꢃ
BF4]ꢁ. Anal. Found: C,
52.07; H, 3.04. C50H38AgBF4FeP2Pt requires C, 52.39;
H, 3.34%. Upon standing a solution of 3 in a CH2Cl2ꢂ
C6H14 mixture, tiny yellow crystals were formed after 1
day which was characterized as compound 5 (yield:
77%). IR (KBr, cmꢃ1): 2078w (nCꢀC). 1H-NMR
(CDCl3): d 3.97 (s, 8H, C5H4), 4.34 (s, 8H, C5H4),
/
6.92 (m, 4H, Cꢀ
/
CPh), 7.14ꢂ
7.75 (m, 8H,
2648
/
7.23 (m, 6H,
4.2.2. Synthesis of [Pt(dppf)(Cꢀ
/
CPh)2] (1)
/
/
7.42 (m, 12H, Ph), 7.68ꢂ
/
Phenylacetylene (153.0 mg, 1.50 mmol) was added to
a suspension of [Pt(dppf)Cl2] (410.0 mg, 0.50 mmol) and
CuI (20 mg) in iPr2NH (25 ml) and CH2Cl2 (25 ml). The
mixture was stirred overnight (16 h) at r.t., during which
time it turned to a milky suspension. After filtration, the
solid was washed with MeCN and CH2Cl2, dissolved in
a little hot CHCl3 and subjected to a short silica column
using CH2Cl2 as eluent. From the first yellow band, a
light yellow solid of 1 was obtained in 63% yield (300.0
ꢀ
/
/
/
mg). IR (KBr, cmꢃ1): 2112m, 2120m (nCꢀC). H-NMR
1
6.73ꢂ
CPh), 7.05ꢂ
Ph). 31P{1H}-NMR (CDCl3): d 14.21 (1JPtꢁP
Hz). ESI-MS (m/z): 2011 [Mꢃ
BF4]ꢁ. Anal. Found: C,
/
6.75 (m, 8H, Cꢀ
/
CPh), 6.95ꢂ
/
6.99 (m, 12H, Cꢀ
7.60 (m, 16H,
2506
/
(CDCl3): d 4.19 (s, 4H, C5H4), 4.31 (s, 4H, C5H4), 6.77ꢂ
6.81 (m, 4H, CꢀCPh), 6.96ꢂ7.00 (m, 6H, CꢀCPh),
7.27ꢂ7.40 (m, 12H, Ph), 7.81ꢂ7.88 (m, 8H, Ph).
/
/
7.34 (m, 24H, Ph), 7.56ꢂ
/
/
/
/
ꢀ
/
/
/
/
31P{1H}-NMR (CDCl3): d 15.95 (1JPtꢁP
ꢀ2365 Hz).
/
56.98; H, 3.44. C100H76AgBF4Fe2P4Pt2 requires C,
57.25; H, 3.65%.
FAB-MS (m/z): 952 [M]ꢁ. Anal. Found: C, 63.02; H,
3.91. C50H38FeP2Pt requires C, 63.10; H, 4.02%.

W.-Y. Wong et al. / Journal of Organometallic Chemistry 659 (2002) 107ꢂ
/116
115
Table 4
Summary of crystal structure data for complexes 1×C4H8O, 4 and 5
1×C4H8O
54H46FeOP2Pt
4
5
Empirical formula
Molecular weight
Crystal system
Space group
C
C100H76BCuF4Fe2P4Pt2
2053.72
C100H76AgBF4Fe2P4Pt2
2098.12
Triclinic
1023.79
Monoclinic
P21/n
Monoclinic
P21/n
¯
/
P1/
˚
a (A)
12.7678(9)
21.6216(15)
16.3142(11)
90
23.0719(12)
13.9947(8)
26.9575(14)
90
14.8883(15)
17.6379(17)
18.6819(19)
84.228(2)
84.668(2)
75.658(2)
4717.1(8)
2
˚
b (A)
˚
c (A)
a (8)
b (8)
98.1040(10)
90
91.3340(10)
90
g (8)
3
U (A )
˚
4458.7(5)
4
3.570
8701.8(8)
4
3.899
Z
m(Moꢂ
/
Ka) (cmꢃ1
)
F(000)
Crystal size (mm)
2048
0.30ꢄ0.26ꢄ0.22
4056
0.33ꢄ0.14ꢄ0.09
2064
0.27ꢄ0.13ꢄ0.08
u Range (8)
1.87ꢂ/27.51
1.77ꢂ/27.52
1.42ꢂ27.55
/
Reflections collected
Unique reflections
Observed reflections [I ꢀ2s(I)]
Parameters
25 893
10 008
50 486
19 519
28 388
20 538
20 538
10 008
533
0.0221
19 519
1028
0.0972
Rint
0.1211
0.1057, 0.2633
R1, wR2 [I ꢀ2s(I)]
R1, wR2 (all data)
Goodness-of-fit
0.0200, 0.0490
0.0267, 0.0514
0.927
0.0448, 0.0760
0.1485, 0.0974
0.851
0.949
ꢃ3
˚
Residual extrema in final difference map (e A
)
0.534 to ꢃ0.401
1.049 to ꢃ0.691
5. Crystallography
6. Supplementary material
Single crystals of 1×
lographic analyses were grown by slow evaporation of
its solution in THFꢂhexane and those of 4 and 5 in
hexaneꢂCH2Cl2 at room temperature. The crystals for 1
and 4 were glued on a glass fiber with epoxy resin while
that for 5 was mounted in a glass capillary. Crystal data
and other experimental details are summarized in Table
4. (For 5, only the cell parameters and some details of
the refinement are shown.) The diffraction experiments
were carried out at room temperature on a Bruker Axs
SMART 1000 CCD area-detector diffractometer using
/
C4H8O suitable for X-ray crystal-
Crystallographic data (comprising hydrogen atom
coordinates, thermal parameters and full tables of
bond lengths and angles) for the structural analysis
has been deposited with the Cambridge Crystallographic
Centre, CCDC nos. 185415 and 185416 for compounds
1 and 4 respectively. Copies of this information may be
obtained free of charge from The Director, CCDC, 12
/
/
Union Road, Cambridge CB2 1EZ, UK (Fax: ꢁ44-
/
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
graphite-monochromated Moꢂ
/
Ka radiation (lꢀ
/
Acknowledgements
˚
0.71073 A). The collected frames were processed with
the software SAINT [19a] and an absorption correction
was applied (SADABS [19b]) to the collected reflections.
The space groups for all crystals were determined
from a combination of Laue symmetry check and their
systematic absences, which were then confirmed by
successful refinement of the structures. The structures
were solved by direct methods (SHELXTL [20]) in
conjunction with standard Fourier difference techniques
and subsequently refined by full-matrix least-squares
analyses. All non-hydrogen atoms were refined with
anisotropic displacement parameters for 1 and 4. The
hydrogen atoms were placed in their ideal positions but
not refined.
Financial support from the Hong Kong Baptist
University is gratefully acknowledged. We also thank
the Hong Kong Research Grants Council for the
purchase of LC-MS instrument for the electrospray
mass spectral analyses.
References
[1] (a) H. Lang, D.S.A. George, G. Rheinwald, Coord. Chem. Rev.
206ꢂ207 (2000) 101 (and references cited therein);
/
(b) P.R. Raithby, M.J. Rosales, Adv. Inorg. Chem. Radiochem.
29 (1985) 169;
(c) M.I. Bruce, Chem. Rev. 91 (1991) 197;

116
W.-Y. Wong et al. / Journal of Organometallic Chemistry 659 (2002) 107ꢂ116
/
(d) H. Lang, K. Kohler, S. Blau, Coord. Chem. Rev. 143 (1995)
¨
113;
(c) M. Hissler, W.B. Connick, D.K. Geiger, J.E. McGarrah, D.
Lipa, R.J. Lachicotte, R. Eisenberg, Inorg. Chem. 39 (2000) 447;
(d) S.L. James, M. Younus, P.R. Raithby, J. Lewis, J. Organomet.
Chem. 543 (1997) 233;
(e) I. Manners, Angew. Chem. Int. Ed. Engl. 35 (1996) 1602;
(f) S. Lotz, P.H. van Rooyen, R. Meyer, Adv. Organomet. Chem.
37 (1995) 219;
(e) C.J. Adams, S.L. James, P.R. Raithby, Chem. Commun.
(1997) 2155.
(g) G. Erker, Comments Inorg. Chem. 13 (1992) 111;
(h) R. Nast, Coord. Chem. Rev. 47 (1982) 89.
[8] B. Corain, B. Longato, G. Favero, D. Ajo`, G. Pilloni, U. Russo,
F.R. Kreissl, Inorg. Chim. Acta 157 (1989) 259.
[9] M. Younus, Ph.D. thesis, University of Cambridge, 1996.
[2] (a) S. Back, G. Rheinwald, H. Lang, J. Organomet. Chem. 601
(2000) 93;
(b) W. Frosch, S. Back, K. Kohler, H. Lang, J. Organomet.
¨
[10] C.V. Ursini, G.H.M. Dias, M. Horner, A.J. Bortoluzzi, M.K.
¨
Morigaki, Polyhedron 19 (2000) 2261.
Chem. 601 (2000) 226;
(c) A. Kova´cs, G. Frenking, Organometallics 18 (1999) 887;
(d) S. Back, H. Lang, Organometallics 19 (2000) 749;
(e) C.J. Adams, P.R. Raithby, J. Organomet. Chem. 578 (1999)
178;
[11] P.S. Pregosin, R.W. Kunz, in: P. Diehl, E. Fluck, R. Kosfeld
(Eds.), NMR Basic Principles and Progress, vol. 16, Springer-
Verlag, New York, 1979, p. 43.
[12] J.D. Bradshaw, L. Guo, C.A. Tessier, W.J. Youngs, Organome-
tallics 15 (1996) 2582.
(f) V.W.-W. Yam, K.-L. Yu, K.M.-C. Wong, K.-K. Cheung,
Organometallics 20 (2001) 721.
[13] (a) L.R. Falvello, J. Fornie´s, J. Go´mez, E. Lalinde, A. Mart´ın,
M.T. Moreno, J. Sacrista´n, Chem. Eur. J. 5 (1999) 474;
(b) H.-K. Yip, H.-M. Lin, Y. Wang, C.-M. Che, J. Chem. Soc.
Dalton Trans. (1993) 2939;
[3] U. Belluco, R. Bertani, R.A. Michelin, M. Mozzon, J. Organo-
met. Chem. 600 (2000) 37.
[4] G. Bandoli, A. Dolmella, Coord. Chem. Rev. 209 (2000) 161.
[5] W.-Y. Wong, F.-L. Ting, W.-L. Lam, Eur. J. Inorg. Chem. (2001)
623.
(c) M. Bonamico, G. Dessy, V. Fares, M.V. Russo, L. Scar-
amuzza, Cryst. Struct. Commun. 6 (1977) 39.
[6] (a) W.-Y. Wong, G.-L. Lu, K.-F. Ng, K.-H. Choi, Z. Lin, J.
Chem. Soc. Dalton Trans. (2001) 3250;
[14] S. Yamazaki, A.J. Deeming, J. Chem. Soc. Dalton Trans. (1993)
3051.
(b) W.-Y. Wong, W.-K. Wong, P.R. Raithby, J. Chem. Soc.
Dalton Trans. (1998) 2761;
[15] I. Ara, J.R. Berenguer, J. Fornies, E. Lalinde, M.T. Moreno, J.
Organomet. Chem. 510 (1996) 63.
[16] W.-Y. Wong, G.-L. Lu, K.-F. Ng, C.-K. Wong, K.-H. Choi, J.
(c) W.-Y. Wong, K.-H. Choi, G.-L. Lu, J.-X. Shi, Macromol.
Rapid Commun. 22 (2001) 461;
Organomet. Chem. 637ꢂ639 (2002) 159.
/
(d) W.-Y. Wong, S.-M. Chan, K.-H. Choi, K.-W. Cheah, W.-K.
Chan, Macromol. Rapid Commun. 21 (2000) 453;
(e) H. Zhang, A.W.-M. Lee, W.-Y. Wong, M.S.-M. Yuen, J.
Chem. Soc. Dalton Trans. (2000) 3675.
[17] W.L.F. Armarego, D.D. Perrin, Purification of Laboratory
Chemicals, 4th ed., Butterworth-Heinemann, Guildford, 1996.
[18] P.J. Kuhba, Inorg. Chem. 28 (1990) 78.
[19] (a) SAINT, Reference manual, Siemens Energy and Automation,
[7] (a) C.J. Adams, S.L. James, X. Liu, P.R. Raithby, L.J. Yellow-
lees, J. Chem. Soc. Dalton Trans. (2000) 63;
(b) S.M. ALQaisi, K.J. Galat, M. Chai, D.G. Ray, III, P.L.
Rinaldi, C.A. Tessier, W.J. Youngs, J. Am. Chem. Soc. 120 (1998)
12149;
Madison, WI, 1994ꢂ
/
1996;
(b) G.M. Sheldrick, SADABS, Empirical Absorption Correction
Program, University of Gottingen, 1997.
¨
[20] G.M. Sheldrick, SHELXTLTM, Reference manual, ver. 5.1, Madi-
son, WI, 1997.