Peripherally-metallated porphyrins: Synthesis and spectra of meso-η1-palladio- and platinioporphyrins and the crystal structures of cis-{PtBr[10,20-diphenylporphyrinatonickel(II)-5-yl](PPh3) 2} and trans-{PtBr[10,20-diphenylporphyrin-5-yl](PPh3) 2}·0.25CH2Cl2

Article abstract of DOI:10.1016/S0022-328X(00)00185-6

A series of meso-η¹-palladio(II)- and platinio(II)porphyrins containing either monodentate Group 15 ligands (PPh₃, AsPh₃) or chelating diphosphines (dppe, dppp, dppf) has been prepared by oxidative addition of mono- and dibromo derivatives of 5,15-diphenylporphyrin (H₂DPP) to Pd(O) and Pt(O) precursors. The products were characterized by their ¹H- and ³¹P-NMR, visible absorption, and mass spectra and the X-ray crystal structures of trans-[PtBr(H₂DPP)(PPh₃)₂] (14) (as a 0.25CH₂Cl₂ solvate) and cis-[PtBr(NiDPP)(PPh₃)₂] (15) were determined. The structures show approximately square planar geometry about the Pt atoms, although there are distortions due to crowding of the PPh₃ ligands in 15. The NiDPP ring in 15 suffers ruffling typical of peripherally-crowded Ni(II) porphyrins, the pairs of opposite meso carbons being displaced alternately > ± 0.4 A? out of the C₂₀N₄ mean plane The conformations of the phenyl groups of the PPh₃ ligands indicate the presence of non-covalent phenyl-porphyrin π-π interactions. These derivatives are the first isolated examples of peripheral organometallic porphyrins with direct transition metal to porphyrin σ-bonds, and they represent a new class of superstructured porphyrins with one or both faces of the macrocycle heavily shielded by the phenyl groups on the auxiliary ligands.

Full text of DOI:10.1016/S0022-328X(00)00185-6

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 607 (2000) 41–50
Peripherally-metallated porphyrins: synthesis and spectra of
meso-h1-palladio- and platinioporphyrins and the crystal structures
of cis-{PtBr[10,20-diphenylporphyrinatonickel(II)-5-yl](PPh3)2} and
trans-{PtBr[10,20-diphenylporphyrin-5-yl](PPh3)2}·0.25CH2Cl2
Dennis P. Arnold a,*, Peter C. Healy b, Margaret J. Hodgson a, Michael L. Williams b
a Centre for Instrumental and De6elopmental Chemistry, Queensland Uni6ersity of Technology, GPO Box 2434, Brisbane 4001, Australia
b School of Science, Griffith Uni6ersity, Nathan 4111, Australia
Received 13 January 2000; received in revised form 11 March 2000
Dedicated to Professor Martin Bennett on the occasion of his retirement.
Abstract
A series of meso-h1-palladio(II)- and platinio(II)porphyrins containing either monodentate Group 15 ligands (PPh3, AsPh3) or
chelating diphosphines (dppe, dppp, dppf) has been prepared by oxidative addition of mono- and dibromo derivatives of
5,15-diphenylporphyrin (H2DPP) to Pd(0) and Pt(0) precursors. The products were characterized by their 1H- and 31P-NMR,
visible absorption, and mass spectra and the X-ray crystal structures of trans-[PtBr(H2DPP)(PPh3)2] (14) (as a 0.25CH2Cl2 solvate)
and cis-[PtBr(NiDPP)(PPh3)2] (15) were determined. The structures show approximately square planar geometry about the Pt
atoms, although there are distortions due to crowding of the PPh3 ligands in 15. The NiDPP ring in 15 suffers ruffling typical of
,
peripherally-crowded Ni(II) porphyrins, the pairs of opposite meso carbons being displaced alternately \ 90.4 A out of the
C20N4 mean plane The conformations of the phenyl groups of the PPh3 ligands indicate the presence of non-covalent
phenyl–porphyrin p–p interactions. These derivatives are the first isolated examples of peripheral organometallic porphyrins with
direct transition metal to porphyrin s-bonds, and they represent a new class of superstructured porphyrins with one or both faces
of the macrocycle heavily shielded by the phenyl groups on the auxiliary ligands. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Palladium; Platinum; Porphyrins; Oxidative addition; Crystal structures
diporphyrins bridged by various conjugated and par-
tially-conjugated unsaturated linkers [4], and have in-
1. Introduction
vestigated the novel spectroscopic properties of
electrogenerated anions of these dimers [5]. Many other
research groups have been active in this area, and have
employed Pd catalysis to prepare a spectacular variety
of covalently-linked multi-porphyrin arrays. Couplings
of the Heck, Suzuki, Sonogashira and Stille types,
amongst others, have so far been used [6–10]. One
particularly useful reaction is the coupling of meso-
haloporphyrins with organotin or organozinc com-
pounds [9,10], or with terminal alkynes [6,7]. The use of
5,15-diarylporphyrins such as 5,15-diphenylporphyrin
(H2DPP, 1) in this area was pioneered by Therien’s
group [10], and this porphyrin is ideal for chemistry at
the remaining lateral meso positions, since these two
The oxidative addition of aryl halides to M(0) phos-
phine complexes has been used for many years to
prepare arylpalladium(II) and -platinum(II) compounds
[1]. Recently, some attention has been paid to this
reaction as a means of preparing interesting arylene-
bridged dimetallic organometallics of the nickel triad
[2]. We have been pursuing the use of Pd-catalyzed
couplings for the preparation of novel porphyrin com-
pounds since our first publication in 1993 [3]. In partic-
ular, we have used such couplings to prepare
* Corresponding author. Tel.: +61-7-38642482; fax: +61-7-
38641804.
E-mail address: d.arnold@qut.edu.au (D.P. Arnold).
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00185-6

42
D.P. Arnold et al. / Journal of Organometallic Chemistry 607 (2000) 41–50
edges of the macrocycle are sterically unencumbered. In
couplings of the meso-haloporphyrin using Pd(0) and
phosphines, an essential step is the oxidative addition
to form a meso-h1-palladioporphyrin [10].
2. Results and discussion
2.1. Syntheses and general properties of Pd compounds
Our interest in pursuing this chemistry stemmed from
an experiment in which a Stille coupling was attempted
using Pd(PPh3)4 as a catalyst. The particular reaction
was very sluggish, even after extended heating. More
and more catalyst was added, and eventually an impure
compound possessing P-phenyl resonances in its 1H-
NMR spectrum was isolated. This compound decom-
posed on standing in CDCl3 solution, to form
unsubstituted NiDPP. Contemplation of these facts led
to the supposition that we had isolated the intermediate
organopalladium(II) porphyrin. This postulate was
readily confirmed by carrying out the reaction of the
Until our preliminary communication [11], there were
no reports of the isolation of such compounds. Indeed,
characterized examples of directly-bonded meso-metal-
loporphyrins are very few in number [12,13].
Organometallic chemistry of metals coordinated at the
centre of porphyrins is, of course, well established [14],
and one group has studied h5-octaethylporphyrinyl
Ru(II) and Ir(III) complexes with one pyrrole ring
p-coordinated to the metal moieties [15]. To initiate our
research in this field, we prepared a range of derivatives
of the type shown in Table 1, as an initial survey of the
synthesis of this class of compounds containing Pd(II)
and Pt(II). We now report in more detail on their
synthesis and spectra, as well as detailing the first
examples of single crystal X-ray structure determina-
tions of h1-platinioporphyrins. Our interest in these
species is prompted, not only by their intrinsic novelty
and their intermediacy (for Pd) in catalytic couplings,
but also their potential applications. Currently, por-
phyrins are being applied in fields such as material
science, supramolecular engineering, non-linear optics
and biomimetic catalysis, and the marriage of por-
phyrins with organometallic chemistry at the periphery
of the macrocycle may open new and useful avenues for
both pure and applied research.
haloporphyrin with
a
stoichiometric amount of
Pd(PPh3)4 in near-boiling toluene as solvent, these con-
ditions being chosen on the basis of a previous experi-
ence of one of us (while working with Martin Bennett)
with similar reactions using aryl bromides and Pt(0)
[16]. The first substrate tried was NiDPPBr (4), and it
was clear from TLC that a rapid reaction had occurred.
When no further change was apparent (less than 40
min), the solvent was removed, and the glassy residue
was triturated with ether to dissolve selectively the
excess phosphine, leaving the organopalladiumpor-
1
phyrin as a solid residue. This material exhibited H-
and 31P-NMR spectra as expected for structure 6
(Table 1). This method was also used to prepare the
analogous free base 7.
Table 1
Structures of starting materials and products
In order to broaden the scope of these reactions, the
universal precursor Pd2dba3 (dba=dibenzylideneace-
tone) was tried in combination with PPh3, AsPh3, and a
range of bidentate diphosphines, using as substrates
both 6 and 7, as well as the nickel(II) complex (5) of the
dibromoporphyrin (3). In all cases, quantitative conver-
sion of the haloporphyrins to palladioporphyrins was
demonstrated by TLC. In this initial synthetic study, in
which we used very small scale preparations in most
cases, we have not quantified the isolated yields of all
products, nor optimized the isolations, but rather have
concentrated on obtaining good characterization data.
In some cases though, we were able to isolate and
recrystallize the products in yields up to 65% (e.g. for
9), with losses occurring because of the need to remove
dba and excess phosphine–arsine ligands. Apart from
the partial exchange of chloro for the bromo ligand
(encouraged by the high trans-effect of the s-bound
porphyrin ligand), the compounds all survive recrystal-
lization from dichloromethane–hexane, and also
dichloromethane–methanol, provided that the precipi-
tation is fairly rapid. Storage in solution in the presence
of methanol for more than a day resulted in protolysis
of the Pdꢀporphyrin bond, forming either H2DPP or
NiDPP as expected. The compounds were stable
Compound
M
X
Y
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
H2
H2
Ni
Ni
Ni
H2
H2
Ni
H2
H2
H2
H2
H2
Ni
Ni
Ni
H
Br
H
Br
H
H
H
Br
Br
Br
Br
PdBr(PPh3)2
PdBr(PPh3)2
Pd(AsPh3)2
PdBr(PPh3)2
PdBr(dppe)
PdBr(dppp)
PdBr(dppf)
cis-PtBr(PPh3)2
trans-PtBr(PPh3)2
cis-PtBr(PPh3)2
trans-PtBr(PPh3)2
Trans-PtBr(PPh3)2
PdBr(PPh3)2
H
H
H
H
H
H
H
PdBr(PPh3)2

D.P. Arnold et al. / Journal of Organometallic Chemistry 607 (2000) 41–50
43
1
enough in CDCl3 to enable good H- and 31P-NMR
spectra to be obtained. Unfortunately, these DPP
derivatives are not sufficiently soluble in solvents other
than dichloromethane and chloroform to enable us to
obviate the chloro–bromo exchange completely. More-
over, the double oxidative addition of the dibromo free
base 3 was unsuccessful under our conditions, because
the starting material is very insoluble in toluene, even at
near-boiling temperatures. We are about to embark on
the use of more soluble porphyrins as a way around
these problems.
product which is more mobile on TLC. By interrupting
the reaction during this conversion, and isolating the
products by column chromatography, we showed by
NMR spectroscopy, that the first addition products are
the respective cis isomers 13 and 15. The final products
are the trans isomers 14 and 16. This isomerization is
presumably assisted by the presence of the one equiva-
lent of excess phosphine released in the addition pro-
cess, since the two cis species are geometrically stable
after removal of the excess ligand, and survive un-
changed through column chromatography and slow
crystallization. The geometry of these products was
confirmed by crystal structure determinations of 14 and
15 (see below). In the case of the Pd(II) analogues
above, the corresponding cis isomers were not ob-
served. In oxidative additions of aryl halides to Ni(0),
Pd(0) and Pt(0), the trans isomers are the usual prod-
ucts for all the metals [18]. The Pt(II) complexes are
more stable than the Pd(II) analogues, as expected from
the well-known simpler aryl organometallics.
We were also able to prepare the heterometallic
bis-adduct 17 by first adding one equivalent of
Pt(PPh3)3 under the usual conditions, heating for 3 h,
then adding the required amounts of Pd2dba3 and PPh3
to complete the Pd(0) insertion. It was clear when
trying to insert a second Pt(PPh3)2 into NiDPPBr2, that
the second addition is much slower than the first. The
Pt(PPh3)2Br substituent appears to exert a considerable
substituent effect on the porphyrin ring. This conclu-
sion is reinforced by the fact that the derivatives 13 and
14 are stronger bases than, say, the starting material
H2DPPBr. During both TLC and column chromatogra-
phy on silica gel, it was necessary to take the precaution
of de-acidifying or adding triethylamine to the
dichloromethane to prevent the formation of green
protonated species. This did not seem to be necessary
for the corresponding Pd complex 7.
For the bidentate diphosphines dppe, dppp and dppf,
the reactions proceeded similarly to those for the
monophosphines. The last of these ligands was recom-
mended by Therien as being particularly active in catal-
ysis of coupling reactions with bromoporphyrins [10].
In the preliminary communication [11], it was reported
that the reaction for dppe required some 8 h heating.
Reinvestigation revealed that the reaction in fact is
faster than this, and is complete within 2.5 h. The
fastest of these reactions is that for dppf, which accords
with its good performance in coupling reactions. Reac-
tion under the same conditions using the ligand cis-1,2-
bis(diphenylphosphino)-ethylene led to the isolation of
only the H2DPP ligand, and no organopalladiopor-
phyrin was observed. Reasons for this aberration were
not addressed, but the result is consistent with the
rigidity of the alkenyl chelate ring being deleterious to
the oxidative addition in these rather crowded systems.
The use of Pd complexes containing the dba ligand in
catalytic processes has generated some dispute in the
literature, and there have been several papers address-
ing the exact nature of the Pdꢀdba species present in
solution and of the complexes formed in situ by the
addition of various proportions of mono- and bidentate
phosphines [17]. In the present work, we were not
interested in this problem per se, but rather we were
concentrating on simply finding conditions which gave
good yields of our porphyrin products. We found that
use of a ratio porphyrin–Br:Pd2dba3 of 2:1 gave only
50% conversion of the substrate, and hence for all our
experiments we used two equivalents of Pd per por-
phyrin, with enough Group 15 ligand to give a ratio of
\2P(As) per Pd.
2.3. NMR spectra
The Pd complexes with monodentate Group 15 lig-
1
ands, namely 6–9, all exhibited sharp H-NMR spectra
which were readily assignable from integration and
comparison with the spectra of the starting porphyrins.
Partial exchange of Cl for Br led to the observation of
small peaks almost coincident with those of the bromo
complexes. The phenyl groups of the PPh3 and AsPh3
ligands appeared upfield of the CHCl3 signal, as ex-
pected for their location (on average) in the shielding
zone of the magnetically anisotropic porphyrin ligand,
because the LꢀPdꢀL vector spends most time approxi-
mately orthogonal to the porphyrin plane. Clearly the
rotation of the PdL2Br moiety about the Pdꢀporphyrin
bond is slow enough on the NMR timescale at 300
MHz (and the rotations about the PdꢀL and P/AsꢀPh
bonds are fast enough), that sharp signals are observed
2.2. Syntheses and general properties of the Pt
compounds
For oxidative additions to Pt(0), so far we have
investigated only PPh3 as a co-ligand. Thus the bromo-
porphyrins 2 and 4 were reacted with Pt(PPh3)3 in hot
toluene, and in both cases the conversion of the starting
material to Pt(II) complexes was evident by TLC al-
most immediately upon mixing. In each of these cases,
however, it was clear that the initially-formed Pt(II)
complex was being slowly converted into another

44
D.P. Arnold et al. / Journal of Organometallic Chemistry 607 (2000) 41–50
The 31P spectra of the chelated derivatives of between
2
Pd(II) all show the expected AB spectra, with JPP
typical for these ligands. For the trans Pt(II) complexes
14 and 16, singlet 31P resonances with 195Pt satellites
1
were observed, with JPtP values as expected for trans
bis(phosphine) complexes (ca. 2950 Hz). This is also
true for one of the 31P resonances for the trimetallic
derivative 17. For the cis isomers, the widely-differing
1
trans-influences of the ligands result in JPtP values of
Fig. 1. Geometry of the trans-bis(triphenylphosphine) derivatives and
the possible rotations and oscillations about the bonds in the dppf
derivative 12.
4276 and 4248 Hz for P trans to Br and 1775 and 1795
Hz for P trans to DPP for 13 and 15, respectively. Thus
the meso-h1-porphyrin ligand behaves on Pt(II) as a
typical s-bound hydrocarbyl group. Interestingly, for
13 the two intrinsically non-equivalent phosphorus nu-
clei are accidentally isochronous, but the appearance of
the satellites as doublets (1JPP 17.2 Hz) with PtꢀP
coupling constants as above, unambiguously determines
the stereochemistry about Pt. For the Ni(II) complex
15, the two 31P signals differ in chemical shift by only
0.4 ppm.
Some informative trends have emerged by comparing
the chemical shifts of the porphyrin protons across the
present series. As usual, the b-pyrrole and meso protons
for the Ni(II) complexes appear upfield of those for the
corresponding free bases. Of more novelty are the
upfield shifts of the b-pyrrole protons, and also those of
the 10,20-phenyl groups, when both the 5- and 15-car-
bons are substituted with very large metal-centred sub-
stituents, (compounds 9 and 17). This may be due to
out-of-plane distortion of the porphyrin macrocycle
(saddling or ruffling) [20].
for these phenyl protons. Compared with the bromo-
porphyrins, small changes are apparent in the chemical
shifts of the 10,20-phenyl protons, the b-pyrrole pro-
tons (which appear as usual as doublets, J:4.8 Hz),
and the remaining 15-meso-proton (for 6–8). The
31P{1H} spectra of 6, 7 and 9 exhibit singlet resonances
near 30 ppm. The signals for the b-protons on carbons
3 and 7 flanking the large metallo substituent appear
well downfield from the others, in the same region as
the 15-meso-proton.
The situation is more complex for the chelating
diphosphines. The proton signals for the phenyl groups
overhanging the porphyrin plane shift even further
upfield than for 6–9, although for the dppe and dppp
products 10 and 11, the signals remain fairly sharp.
However, for the ferrocenyl derivative 12, the signals
for the protons on one of the Cp rings are broad,
especially the signal at 4.9 ppm and, to a lesser extent,
its partner at 4.55 ppm. Moreover, the signals in the
region 5–7 ppm for one pair of phenyl groups (by
comparison with the rest of the series, the phenyls on
the P cis to DPP) are extremely broad. By considering
the various intramolecular motions possible for 12, it is
reasonable to assume that this behavior is due to
restricted rotation(s) and/or oscillation(s) about the
bonds indicated in Fig. 1, as well as within the ferro-
cenyl moiety. This behavior is also exhibited by one set
of phenyl groups of the cis isomers 13 and 15 of the
platinum(II) complexes. Indeed in the Ni complex 15,
the signals due to the ortho protons of the 10,20-phenyl
groups are also broad at room temperature. We will be
undertaking variable temperature studies to clarify
these aspects. The X-ray crystal structure of the dppe
derivative 10 was described briefly in our preliminary
communication [11], and will not be discussed further
here, except to note the confirmation of the fact that
the phenyl groups on the cis phosphorus atom extend
almost half-way across the porphyrin (when their posi-
tions are averaged by dppe chelate ring flipping). This is
also true for the Pt derivatives 14 and 15 (see below).
We propose the use of these or similar peripheral
metal-centred substituents as a means of shielding the
faces of the macrocycle and hence creating tailored
cavities thereon [19].
2.4. Mass and UV–6is absorption spectra
All the complexes in the series except for the dppp
complex 11 gave molecular ions (or protonated molecu-
lar ions for those containing H2DPP) in FAB mass
spectra. Because of the use of dichloromethane as a
solvent for introducing the compounds into the matrix,
the molecular ions of the chloro complexes were also
observed in the case of the Pd derivatives (including the
trimetallic complex 17). This phenomenon was also
observed for the free base Pt derivatives 13 and 15, but
not for 14 and 16. Additionally, ions with m/z appro-
priate for (M+HCl)+ or (M+HCl+H)+ were ob-
served for 13 and 15. Fragmentation was also apparent,
and logical losses could be easily recognized. For exam-
ple, although 11 did not exhibit a molecular ion, the
fragments [Pd(dppp)Br], [Pd(dppp)] and H2DPP were
observed, as well as the dimer [Pd(dppp)Br]2. The simi-
lar compound 10 gave only a very weak molecular ion
cluster. The laser desorption technique (with or without
matrix) did not allow the observation of any molecular
ions, but unusually for this technique, extensive frag-
mentation was apparent.

D.P. Arnold et al. / Journal of Organometallic Chemistry 607 (2000) 41–50
45
2.5. Crystal structures of 14 and 15
The visible absorption spectra were typical for DPP
derivatives. The wavelengths of the principal visible
absorption bands for all the complexes and their pre-
cursors are collected in Table 2. Several trends are
apparent, even in this limited set of data. All groups
other than H in the 5- or 5- and 15-positions cause a
red-shift for both the free bases and central metal
complexes, and such shifts are typical of DPP systems
[6,10]. The spectra are sensitive to the steric demands of
the meso substituents, as seen by comparison between
the dppe complex 10, and the similar chelated deriva-
tives 11 and 12, and also between the cis and trans
isomers of the Pt derivatives. Moreover, for the doubly-
substituted complex 9, there is a significant red-shift of
all bands with respect to its monosubstituted analogue
7, amounting to 1000 cm−1 for the Soret bands. Per-
haps this is another sign of non-planar distortion of the
porphyrin [20], as suggested above in the discussion of
2.5.1. Trans-[PtBr(H2DPP)(PPh3)2] (14)
The single crystal X-ray structure determination of
this complex shows the molecule crystallizes as discrete
monomers, with two independent molecules in the
asymmetric unit and a co-crystallized molecule of
dichloromethane with 50% occupancy located midway
between the two molecules. The structural arrangement
of these three molecules is shown in Fig. 2. Relevant
geometric parameters are listed in Table 3. For both
molecules, the porphyrin macrocycle is essentially pla-
nar (maximum deviations from the C20N4 mean
,
plane=0.15, 0.15 A). The substituent phenyl groups lie
at dihedral angles to the macrocycle mean plane of
56.8, 71.2° for molecule 1 and 66.3, 93.2° for molecule
2. The two trans PPh3 ligands adopt approximately C3
conformations of opposite chirality and are related by a
pseudo-mirror plane of symmetry with torsion angles
PtꢀP(n)ꢀC(nml)ꢀC(nm2): −61(1), −21(1), −39(1);
79(1), 19(1), 45(1)° for molecule 1 and 74(1), 28(1),
36(1); −80(1), −31(1), −32(1)° for molecule 2. Rings
1 on both ligands in both molecules overhang the
porphyrin ring in face-to face contact with the first
pyrrole ring. The overall conformational structures of
the two molecules are significantly different with the
BrꢀPtꢀC axis lying in the plane of the porphyrin macro-
cycle in molecule 1, while for molecule 2, this axis is
significantly bent out of the plane (Fig. 2).
1
its H-NMR spectrum. The effects of the same ligand
set and geometry for Pd and Pt substituents were
essentially identical, e.g. compare 6 and 16. With regard
to the substituent effects, note also that the Pt(PPh3)2Br
group did have a base-strengthening effect (see above),
perhaps indicating a strong s-inductive influence, with
little p-interaction between the porphyrin and metal
orbitals. It will be interesting to see whether the fluores-
cence emission of free base DPP is quenched by the
presence of the heavy metal at the meso carbon in 7, 8
etc. These studies are planned in the near future.
,
The PtꢀBr distances of 2.518(1) and 2.511(1) A are
marginally longer than the distance of 2.4887(7) A
,
Table 2
recorded for the cis nickel complex 15 (see below),
reflecting the different trans influence of the PPh3 ligand
versus the C donor of the porphyrin ring. The PtꢀC
Wavelengths for the principal UV–vis absorption bands for the
meso-metalloporphyrins and their precursors (in CH2Cl2 solutions)
umax (nm)
,
,
bond length of 2.05(1) A for molecule 1 is 0.1 A longer
,
than the corresponding distance of 1.95 (1) A observed
Soret
IV
III
II
I
for molecule 2. The reasons for this quite remarkable
difference are not immediately apparent, but may be a
reflection of differences in the strength of the phenyl–
pyrrole p–p interactions in the two molecules. Typical
PtꢀC bond lengths involving non-cyclometallated sp2
Free bases
1
2
3
7
405
420
421
418
416
414
426
426
430
434
502
510
520
514
513
509
520
521
523
526
535
545
555
550
548
544
557
558
559
563
575
587
600
587
586
580
592
594
590
599
630
642
658
642
641
634
647
649
650
655
,
carbons are between 1.99 and 2.10 A.
8
10
11
12
13
14
2.5.2. Cis-[PtBr(NiDPP)(PPh3)2] (15)
The single-crystal X-ray structure determination of
15 shows it to crystallize as discrete neutral molecules
separated by normal van der Waals distances. A repre-
sentative view of the molecular structure is shown in
Fig. 3 and selected geometric parameters are listed in
Table 3. The 10,20-phenyl substituents lie at dihedral
angles to the macrocycle mean plane of 78.8 and 108.6°.
As for the complex 14 above, these values are unre-
markable for meso-aryl substituents, e.g. in DPP or
meso-tetraarylporphyrins [6]. The NiN4 geometry is
essentially square planar with NiꢀN distances ranging
Ni complexes
Soret
Q(1,0)
Q(0,0)
NiDPP
4
5
6
9
399
409
419
414
432
424
415
514
523
533
522
538
533
523
547
555sh
vw sh
553
579
579sh
555sh
15
16
,
from 1.914(6) to 1.924(5) A and cis NꢀNiꢀN angles

46
D.P. Arnold et al. / Journal of Organometallic Chemistry 607 (2000) 41–50
Fig. 2. Molecular structure of trans-[PtBr(H2DPP)(PPh3)2] (14), showing the dispositions of molecules A and B and the dichloromethane solvent
molecule, with hydrogen atoms omitted for clarity.
ranging from 89.1(2) to 90.6(2)°. As is well known for
many Ni(II) porphyrin structures [20], the porphyrin
ring is not planar, but rather adopts the ruffled shape,
Table 3
,
Selected bond lengths (A) and bond angles (°) for the complexes
trans-{PtBr[10,20-diphenylporphyrin-5-yl](PPh3)2}·0.25CH2Cl2 (14)
and cis-{PtBr[10,20-diphenylporphyrinatonickel(II)-5-yl](PPh3)2] (15)
,
with C(10) and C(20) 0.4–0.6 A above and C(5) and
,
C(15) 0.4–0.6 A below the mean C20N4 plane. The
porphyrin ring is symmetrically coordinated to the plat-
inum through the C(5) meso carbon, with
PtꢀC(5)ꢀC(4,6) angles of 118.8(4) and 119.9(4)°, respec-
14
15
Molecule A
Molecule B a
,
tively. The PtꢀC(5) bond length of 2.058(5) A is similar
Bond length
PtꢀBr
PtꢀP(1)
PtꢀP(2)
RꢀC(5)
to that of the longer of the two values for the structure
2.518(1)
2.323(3)
2.307(3)
2.05(1)
2.511(1)
2.309(3)
2.325(3)
1.95(1)
2.4887(7)
2.248(2)
2.381(2)
2.058(5)
of 14 described above.
In the triphenylphosphine ligands, the conformations
of the two ligands differ significantly. Ligand 2 (trans
to C) approximates C3 symmetry [PtꢀP(n)ꢀC(nml)ꢀ
C(nm2) torsion angles: 48.1(5), 60.1(6) and 32.2(6)°],
while in ligand 1, the torsion angle in phenyl group 1
increases to 80.2(5)° and in rings 2 and 3 decreases to
17.0(6) and 20.4(6)°, respectively. Fig. 3 shows that the
conformation adopted by ring 1 in this ligand is likely
to be a consequence of face-to-face p–p non-covalent
interactions between the phenyl ring and the pyrrole
Bond angle
BrꢀPtꢀP(1)
BrꢀPtꢀP(2)
BrꢀPtꢀC(5)
P(1)ꢀPtꢀP(2)
P(1)ꢀPtꢀC(5)
P(2)ꢀPtꢀC(5)
89.52(8)
88.88(8)
175.0(3)
176.2(1)
92.6(3)
91.80(9)
91.12(9)
177.2(3)
176.8(1)
89.9(3)
171.08(4)
87.93(4)
83.1(2)
100.94(6)
88.0(2)
89.2(3)
87.3(3)
170.8(2)
a For molecule B, read Pt=Pt(2), P(1)=P(3), P(2)=P(4), Br=
Br(2), C(5)=C(25) (see Fig. 2).

D.P. Arnold et al. / Journal of Organometallic Chemistry 607 (2000) 41–50
47
Fig. 3. Molecular structure of cis-[PtBr(NiDPP)(PPh3)2] (15), with hydrogen atoms omitted for clarity.
moiety of the macrocycle, as noted above for
14, and also clearly seen in the published structure
of Pd complex 10 [11]. The crowding between the two
bulky PPh3 ligands is reflected in (i) the increase in the
PꢀPtꢀP angle to 100.94(6); (ii) the unusually large
PtꢀP(2)ꢀC(221) angle of 126.0(2)°; and (iii) the tetrahe-
dral distortion of the PtP2CBr coordination geometry
about the platinum atom, with P(2)ꢀPtC(5) and
P(1)ꢀPtꢀBr angles of 170.8(2) and 171.08(4)°. To this
anhydrous sodium carbonate. Analytical TLC was car-
ried out on Merck silicagel 60 F254 plates, and column
chromatography was performed using Merck silicagel,
230–400 mesh. NMR spectra were recorded on a
Varian unity 300 instrument in CDCl3 solutions, except
where otherwise noted, using CHCl3 as the reference at
1
7.26 ppm for H spectra, and external 85% H3PO4 as
the reference for the proton-decoupled 31P spectra.
UV–vis spectra were recorded on a Cary 3 spectropho-
tometer in dichloromethane solutions. In some cases,
both chloro and bromo complexes are known to be
present in the products, but extinction coefficients are
quoted using the molecular weight of the bromo spe-
cies. Errors introduced by this will be small since the
molecular weights differ by only about 4%. FAB mass
spectra were recorded on a VG-ZAB instrument at the
Research School of Chemistry, The Australian Na-
tional University, or a Kratos Concept instrument at
the Central Science Laboratory, University of Tasma-
nia. Samples were dissolved in dichloromethane, and
dispersed in a 4-nitrobenzyl alcohol matrix. In the data
below, masses are given for the strongest peak in the
isotope cluster. Elemental analyses were carried out by
the Microanalytical Service, The University of
Queensland.
,
list could be added the large difference of ca. 0. 15 A
between the PtꢀP(1) and PtꢀP(2) bond lengths, al-
though some of this is no doubt due to the widely-dif-
fering trans influences of the ligands Br and s-bound C.
In complex 10, the corresponding difference in the two
,
PdꢀP bond lengths is ca. 0.09 A [11].
3. Experimental
Syntheses involving zerovalent metal precursors were
carried out in an atmosphere of high-purity argon using
conventional Schlenk techniques, but subsequently the
Pd(II) and Pt(II) products were manipulated in air. The
porphyrin starting materials 5,15-diphenylporphyrin
(1), 5-bromo-10,20-diphenylporphyrin (2), 5,15-di-
bromo-10,20-diphenylporphyrin (3) [10], and the re-
spective Ni(II) complexes of the last two derivatives (4,
5) [6] were prepared by literature procedures, as were
the Pd(0) [21] and Pt(0) [22] precursors. All other
reagents and ligands were used as received from Sigma-
Aldrich. Toluene was of AR grade, stored over sodium
wire, and degassed by heating and stirring at 105°
under argon flow. All other solvents were of AR grade,
and dichloromethane and chloroform were stored over
3.1. Syntheses using Pd(PPh3)4
As an example of this method, NiDPPBr (4) (6.9 mg,
0.012 mmol) was added to degassed toluene (5 ml) at
ca. 105° with stirring. Solid Pd(PPh3)4 (12 mg, 0.01
mmol) was added, and heating and stirring were contin-
ued. TLC (elution with 50/50 dichloromethane–hex-
ane) showed completion of the reaction within 40 min.

48
D.P. Arnold et al. / Journal of Organometallic Chemistry 607 (2000) 41–50
The toluene was removed under vacuum, and the
residue was triturated three times with ether. Each time
the supernatant was decanted, then the volatiles were
removed under vacuum, leaving the product
PdBr(NiDPP)(PPh3)2 (6) as purple microcrystals. TLC
showed the absence of the starting material. As de-
scribed in the text above, some exchange to form the
chloro analogue occurred in the presence of chlorinated
solvents. This method was also used to prepare
PdBr(H2DPP)(PPh3)2 (7).
FABMS: 1261.0 (MH+ Anal. Calc. 1261.09), MH+ for
chloro complex also observed.
Data for 9: H-NMR: l 6.7 (36H, m, PPh), 7.2 (24H,
m, PPh), 7.6 (6H, m, m-, p-10,20-Ph), 7.83 (4H, dd,
o-10,20-Ph), 8.08, 9.29 (each 2H, d, b-H); 31P-NMR: l
29.0; UV–vis: umax (m/103 M−1 cm−1) 432 (210), 498
(5.4), 538 (18.1), 579 (9.4) mm; FABMS: 1937.9 (M+
Anal. Calc. 1938.10), M+ for bromochloro and
dichloro complexes also observed.
1
1
Data for 6: H-NMR: l 6.6 (18H, m, PPh), 7.2 (12H,
3.3. Syntheses using Pd2(dba)3 and bidentate
m, PPh), 7.6 (6H, m, m-, p-10,20-Ph), 7.91 (4H, dd,
o-10,20-Ph), 8.24, 8.69, 8.94, 9.40 (each 2H, d, b-H),
9.55 (1H, s, meso-H); 31P-NMR: l 29.8 (chloro com-
plex 30.1); UV–vis: umax (m/103 M−1 cm−1) 414 (210),
484 sh (3.5), 522 (15.9), 553 sh (4.3) nm; FABMS:
1228.0 (M+ Anal. Calc. 1228.10), M+ for chloro com-
plex also observed.
diphosphines
Toluene (10 ml) was added to a Schlenk flask and
heated to 105° under a stream of argon. 1,2-Bis(-
diphenylphosphino)ethane (dppe, 32 mg, 0.08 mmol)
was added, followed by Pd2dba3 (18 mg, 0.02 mmol).
The dark purple color of the palladium starting mate-
rial faded rapidly, leaving a clear yellow solution. After
stirring for a further 10 min, H2DPPBr (2) (10.8 mg,
0.02 mmol) was added, and the mixture was stirred at
105° for a further 2.5 h, and the reaction progress was
monitored by TLC using dichloromethane–hexane 1:1
as the eluent. After cooling to room temperature, the
volume was reduced to about one-third under vacuum,
and ether was added to precipitate the product
PdBr(H2DPP)(dppe) (10) as dark purple crystals (17
mg, 80%). The crystal structure of this complex was
reported in our preliminary communication [11]. This
method was also used to prepare 11 (heating for 4 h,
70% yield) and 12. For 12, the bromoporphyrin was
consumed within 40 min, and the product precipitated
directly from the hot reaction mixture. A 60% yield of
12 was obtained by cooling, collecting the brown pow-
der, washing with cold toluene (2 ml), then hexane (2
ml), and vacuum drying.
1
Data for 7: H-NMR (C6D6): l −2.61 (2H, br s,
NH), 6.2–6.4 (18H, m, M), 7.5–7.7 (18H, m, PPh and
m-, p-10,20-Ph), 8.17 (4H, dd, o-10,20-Ph), 8.72 (2H, d,
b-H), 9.08 (4H, br s, 2×b-H), 9.85 (1H, s, meso-H),
10.28 (2H, d, b-H); 31P-NMR (C6D6): l 29.7; UV–vis:
umax (m/103 M−1 cm−1) 400 sh (70.4), 418 (330), 482
(3.6), 514 (13.7), 550 (10.2), 587 (4.4), 642 (6.3) nm;
FABMS: 1173.0 (MH+ Anal. Calc. 1173.19), MH+ for
chloro complex also observed.
3.2. Syntheses using Pd2(dba)3 and monodentate ligands
As an example of this method, H2DPPBr (2) (5.4 mg,
0.01 mmol) was added to degassed toluene (5 ml) at ca.
105° with stirring. Solid AsPh3 (12 mg, 0.04 mmol) and
then Pd2(dba)3 (9 mg, 0.01 mmol) were added, and
heating and stirring were continued. TLC (elution with
50/50 dichloromethane–hexane) showed completion of
the reaction within 5 min. After 20 min, the toluene was
removed under vacuum, and the residue was triturated
three times with ether. Each time the supernatant was
decanted, then the volatiles were removed under vac-
uum, leaving the product PdBr(H2DPP)(AsPh3)2 (8) as
purple microcrystals. TLC showed the absence of the
starting material. As described above, some exchange
to form the chloro analogue occurred in the presence of
chlorinated solvents. This method was also used to
prepare 6, 7, and 9 (using doubled molar amounts of
Pd(0) and Ph3P for 9, and heating for 40 min in each
case). In the case of 6 and 7, it was shown that the
reaction of all the bromoporphyrin required two equiv-
alents of Pd, i.e. PorꢀBr:Pd2dba3=1:1.
Data for 10: 1H-NMR: l −2.95 (2H, br s, NH), 2.53
(4H, m, PCH2), 6.24 (4H, td, m-PPh on P cis to DPP),
6.48 (4H, dd, o-PPh on P cis to DPP), 6.72 (2H, br t,
p-PPh on P cis to DPP), 7.6–7.8 (12H, m, 10,20-Ph and
PPh on P trans to DPP), 8.05 (2H, br d, PPh on P trans
to DPP), 8.24 (2H, br d, PPh on P trans to DPP),
8.3–8.4 (4H, m, 10,20-Ph), 8.52, 8.87, 9.18, 9.52 (each
2H, d, b-H), 9.94 (1H, s, meso-H); 31P-NMR: l 42.6 (d,
JPP 28 Hz), 57.0 (d, JPP 28 Hz); UV–vis: umax (m/103
M−1 cm−1) 397 sh (108), 414 (303), 509 (12.5), 544
(7.5), 580 (5.7), 634 (5.7) nm; FABMS: 1047.1 (MH+
Anal. Calc. 1047.14), MH+ for chloro complex also
observed.
Data for 11: 1H-NMR: l −2.95 (2H, br s, NH), 1.98
(2H, br m, CH2), 2.35–2.5 (4H, br m, PCH2), 5.52 (4H,
td, m-PPh on P cis to DPP), 5.60 (2H, dd, p-PPh on P
cis to DPP), 6.16 (4H, dd, o-PPh on P cis to DPP),
7.55–7.7 (12H, m, 10,20-Ph and PPh on P trans to
DPP), 8.07 (2H, br d, PPh on P trans to DPP), 8.17
(4H, m, 10,20-Ph), 8.29 (2H, br d, PPh on P trans to
1
Data for 8: H-NMR: l −3.41 (2H, br s, NH), 6.4
(18H, m, AsPh), 7.0 (12H, dd, AsPh), 7.7 (6H, m, m-,
p-10,20-Ph), 8.11 (4H, dd, o-10,20-Ph), 8.41, 8.85, 9.14,
9.72 (each 2H, d, b-H), 9.85 (1H, s, meso-H); UV–vis:
umax (m/103 M−1 cm−1) 398 sh (83.0), 416 (319), 480
(4.5), 513 (14.9), 548 (11.0), 586 (4.7), 641 (6.6) nm;

D.P. Arnold et al. / Journal of Organometallic Chemistry 607 (2000) 41–50
49
DPP), 8.65, 8.85, 9.15, 9.82 (each 2H, d, b-H), 9.95
(1H, s, meso-H); 31P-NMR: l −1.4 (d, JPP 53 Hz), 21.2
d, JPP 53 Hz); UV–vis: umax (m/103 M−1 cm−1) 426
(324), 492 (4.0), 520 (14.6), 557 (9.8), 592 (4.8), 647
(6.2) nm.
(6H, m, m-, p-10,20-Ph), 8.10 (4H, dd, o-10,20-Ph),
8.35, 8.80, 9.10, 9.76 (each 2H, d, b-H), 9.82 (1H, s,
meso-H); 31P-NMR: l 27.8 (JPtP 2958 Hz); UV–vis:
umax (m/103 M−1 cm−1) 434 (393), 495 (4.1), 526 (13.6),
563 (11.5), 599 (4.5), 655 (7.5) nm; FABMS: 1261.3
(HM+ Anal. Calc. 1261.25).
Data for 12: 1H-NMR: l −3.25 (2H, br s, NH), 3.65
(2H, br dd, 3,4-Cp trans to DPP), 4.17 (2H, br, 2,5-Cp
trans to DPP), 4.55 (2H, br, 3,4-Cp cis to DPP), 4.9
(2H, vbr, 2,5-Cp cis to DPP), ca. 5.4 (vbr, PPh on P cis
to DPP), 6.2 (vbr, PPh on P cis to DPP), 7.6–7.8 (12H,
m, 10,20-Ph and PPh on P trans to DPP), 8.11 (2H, br
d, PPh on P trans to DPP), 8.26 (2H, br d, PPh on P
trans to DPP), 8.48 (4H, br t, 10,20-Ph), 8.73, 8.84,
9.11, 10.00 (each 2H, d, b-H), 9.81 (1H, s, meso-H);
31P-NMR: l 18.5 (d, JPP 34 Hz), 37.5 (d, JPP 34 Hz);
UV–vis: umax (m/103 M−1 cm−1) 426 (324), 491 (4.4),
521 (14.9), 558 (10.8), 594 (4.9), 649 (6.5) nm; FABMS:
1203.2 (MH+ Anal. Calc. 1203.2). Found: C, 66.2; H,
4.2; N, 4.8. C66H49BrFeNO2Pd requires C, 65.9; H, 4.1;
N, 4.7%.
1
Data for 15: H-NMR: l 6.2 (vbr, Ph on P cis to
DPP), 6.7 (vbr, Ph on P cis to DPP), 7.2–7.4 (m, PPh),
7.6–7.8 (br+m, PPh and m-, p-10,20-Ph), 8.0 (br,
o-10,20-Ph), 8.61, 8.73, 8.92, 9.91 (each 2H, d, b-H),
9.49 (1H, s, meso-H); 31P-NMR: l 22.4 (d, JPP 16.9 Hz,
JPtP trans to Br 4248 Hz), 22.8 (d, JPP 16.9 Hz, JPtP
trans to DPP 1795 Hz); UV–vis: umax (m/103 M−1
cm−1) 424 (183), 533 (13.0), 579 sh (2.8) nm; FABMS:
1318.3 (M+ Anal. Calc. 1318.16).
Data for 16: Found: C, 61.65; H, 3.7; N, 4.2.
C68H49BrN4NiP2Pt requires C, 62.0; H, 3.75; N, 4.25%.
Spectroscopic data for this compound were given in our
preliminary communication [11].
The mixed Pd–Pt complex 17 was prepared as fol-
lows. NiDPPBr2 (5) (8.5 mg, 0.013 mmol) was added to
degassed toluene (5 ml) at ca. 105° with stirring. Solid
Pt(PPh3)3 (12.5 mg, 0.013 mmol) was added, and heat-
ing and stirring were continued. TLC showed almost
complete reaction of 5 within 1 h. The conversion of
the initial cis product to the trans isomer was about
50% complete after 3 h, at which time PPh3 (15.8 mg,
0.06 mmol) and Pd2dba3 (12.4 mg, 0.014 mmol) were
added, and heating and stirring were maintained for a
further 3 h. TLC showed only one major product. The
toluene was removed under vacuum, and the residue
was triturated three times with ether. Each time the
supernatant was decanted, then the volatiles were re-
moved under vacuum, leaving the product
(NiDPP)[PdBr(PPh3)2][PtBr(PPh3)2] (17) as purple
microcrystals.
3.4. Syntheses of Pt(II) complexes
Toluene (5 ml) was added to a Schlenk flask and
heated to 105° under a stream of argon. Pt(PPh3)3 (16
mg, 0.017 mmol) was added, followed by H2DPPBr (9
mg, 0.017 mmol). The reaction mixture was stirred
under argon and a sample was removed for TLC
analysis (CH2Cl2–hexane 1:1) after 12 min. This
showed the presence of the cis isomer 13 as the major,
less mobile product, with a small amount of trans
isomer 14. The reaction mixture was then cooled, and
the solvent was removed under vacuum. The residue
was separated by column chromatography, eluting with
CH2Cl2–hexane/Et3N 80:20:5. Unreacted H2DPPBr
was eluted first, followed by 14 then 13. The isolated 13
was recrystallized from CH2Cl2–hexane. By extending
the heating time to 6 h in a separate experiment, the
trans isomer 14 was isolated as the major product using
CH2Cl2–hexane/Et3N 70:30:1 as eluent, and was recrys-
tallized from CH2Cl2–hexane.
1
Data for 17: H-NMR: l 6.6–6.75 (36H, m, PPh),
7.1–7.3 (24H, m, PPh), 7.7 (6H, m, m-, p-10,20-Ph),
7.84 (4H, m, o-10,20-Ph), 8.07, 8.09, 9.29, 9.48 (each
2H, d, H); 31P-NMR: l 27.5 (PtP, JPtP 2967 Hz), 28.8
(PdP); FABMS: 2026.3 (M+ Anal. Calc. 2027.16), M+
for monochloro complex also observed.
This method was also used to prepare the cis and
trans isomers of the products containing NiDPP, 15
and 16, respectively.
Data for 13: 1H-NMR: l −3.2 (vbr s, NH), 6.0 (vbr,
Ph on P cis to DPP), 6.8 (vbr, Ph on P cis to DPP),
7.2–7.4 (br+m, PPh), 7.7–7.9 (br+m, PPh and m-,
p-10,20-Ph), 8.10, 8.31 (each 2H, br d, o-10,20-Ph),
8.77, 8.82, 9.10, 10.16 (each 2H, d, b-H), 9.81 (1H, s,
meso-H); 31P-NMR: l 22.2 (s, JPtP trans to Br 4276 Hz,
JPtP trans to DPP 1775 Hz, satellites each d, JPP 17.2
Hz); UV–vis: umax (m/103 M−1 cm−1) 430 (370), 493
(4.1), 523 (13.8), 559 (10.0), 590 (4.9), 650 (6.2) nm;
FABMS: 1261.3 (MH+ Anal. Calc. 1261.25).
4. Crystal structure determinations
4.1. Data collection, structure solution and refinement
Crystals of the compounds, suitable for X-ray dif-
fraction studies, were grown by slow diffusion of hex-
ane into dichloromethane solutions of the complexes.
Unique data sets were collected at 293 K with a Rigaku
AFC7R rotating anode diffractometer (ꢀ-2q scan
mode, monochromated Mo–Ka radiation u=0.7107
1
,
Data for 14: H-NMR: l −3.32 (2H, br s, NH),
6.4−6.55 (18H, m, PPh), 7.2–7.3 (12H, m, PPh), 7.7
A) to 2qmax=50% yielding N independent reflections,
N0 with I\2|(I) being considered observed. Empirical

50
D.P. Arnold et al. / Journal of Organometallic Chemistry 607 (2000) 41–50
absorption correction was applied based on „-scans.
The structures were solved by heavy atom Patterson
techniques, expanded by using Fourier techniques and
refined by full-matrix least-squares on ꢀFꢀ using the
TEXSAN crystallographic software package, version 1.8,
from the Molecular Structure Corporation [23]. One
molecule of dichloromethane with 50% occupancy was
located in the structure of 14. Non-hydrogen atoms
were refined anisotropically; (x, y, z, Uiso)H were in-
cluded and constrained at estimated values. The hydro-
gen atoms on the porphyrin nitrogens in the free base
were not located. Statistical weights were employed.
Conventional residues, R, Rw, are quoted at
convergence.
Science, Q.U.T., for a post-graduate scholarship for
M.J.H.
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4.2. Crystal data
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(
H103Br2ClN8P4Pt2, M=2564.7, triclinic P1 (no. 2),
,
a=16.735(3), b=23.358(4), c=15.119(2) A, h=
3
,
95.81(2), i=102.41(1), k=82.05(2)°, V=5701 A ,
Z=2, Dcalc=1.49 g cm−3, F(000)=2562, v=32.8
cm−1, crystal size=0.30×0.30×0.10 mm; Tmin,max
=
0.522, 0.720, N=20 106, N0=10 036 (\2|(I)); R=
0.046, Rw=0.045.
15: cis-[PtBr(NiDPP)(PPh3)2], C68H49BrN4NiP2Pt,
M=1317.8, monoclinic P21/n (no. 14 variant), a=
,
17.932(4), b=10.924(6), c=27.847(6) A, i=97.94(2)°,
3
V=5402 A , Z=4, Dcalc=1.62 g cm−3, F(000)=
,
2624, v=37.7 cm−1, crystal size=0.55×0.15×0.05
mm; Tmin,max=0.629, 0.828, N=10 067, N0=6153 (\
2|(I)); R=0.030, Rw=0.028.
[15] (a) K.K. Dailey, G.P.A. Yap, A.L. Rheingold, T.B. Rauchfuss,
Angew. Chem. Int. Ed. Engl. 35 (1996) 1833. (b) K.K. Dailey,
T.B. Rauchfuss, Polyhedron 16 (1997) 3129.
5. Supplementary material
[16] D.P. Arnold, M.A. Bennett, Inorg. Chem. 23 (1984) 2117.
[17] See for example (a) C. Amatore, A. Jutand, F. Khalil, M.A.
M’Barki, L. Mottier, Organometallics 12 (1993) 3168. (b) C.
Amatore, G. Brocker, A. Jutand, F. Khalil, J. Am. Chem. Soc.
119 (1997) 5176 and refs. therein.
[18] (a) G.W. Parshall, J. Am. Chem. Soc. 96 (1974) 2360. (b) Y.J.
Kim, R. Sato, T. Maruyuma, K. Osakada, T. Yamamoto, J.
Chem. Soc. Dalton Trans. (1994) 943.
[19] H. Ogoshi, T. Mizutani, Acc. Chem. Res. 31 (1998) 81.
[20] See for example (a) J.A. Shelnutt, X.-Z. Song, J.-G. Ma, S.-L.
Jia, W. Jentzen, C.J. Medforth, Chem. Soc. Rev. 27 (1998) 31.
(c) M.O. Senge, M.W. Renner, W.W. Kalisch, J. Fajer, J. Chem.
Soc. Dalton Trans. (2000) 381.
Crystallographic data for the structural analyses have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 141068 and 141069. Copies of
this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge CB2
IEZ, UK [fax: +44-1223-336033] or e-mail: de-
posit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk.
Acknowledgements
[21] D.R. Coulson, Inorg. Synth. 28 (1990) 107.
We thank the Australian Research Council for a
Small Grant to D.P.A. and for financial support for the
purchase of the diffractometer, and the Faculty of
[22] R. Ugo, F. Cariati, G. La Monica, Inorg. Synth. 28 (1990) 123.
[23] TEXSAN, Single Crystal Structure Analysis Software, version 1.8,
Molecular Structure Corporation, Woodlands, TX, 1997.
.