A ditopic catechol phosphane as building block for selective construction of heterometallic complexes with early and late transition metal centers

Article abstract of DOI:10.1002/zaac.201300571

Base-assisted reaction of catechol phosphane 2 (H₂L) with [M′Cl₂(cod)] (cod = 1, 5-cyclooctadiene, M′ = Pd, Pt) yielded chelate complexes [M′(HL)₂] (7a, b). Spectroscopic and single-crystal X-ray diffraction studies revealed that both complexes feature cis-configuration of the P- and O-donor atoms in solution and in the solid state. Reaction of 7a, b with acetylacetonato or alkoxide complexes [MO ₂(acac)₂] (M = Mo, W), [VO(acac)₂], [{Ti(μ-O)(acac)₂}₂], or Ti(OiPr)₄ gave good to excellent yields of early-late heterometallic complexes [MO _n(μ-L)₂M′] (MO_n = MoO₂, WO₂, VO; 8a, b-10a, b) or [Ti(RO-1κO)₂(μ-L- 1κ²O, O'-2κ²P, O)₂Pd] (R = Me, iPr; 11a, b), which were inaccessible via other synthetic routes. Spectroscopic and single-crystal X-ray diffraction studies revealed that the early metal centres in 8a, b, 9b and in 11b feature distorted octahedral coordination spheres with rigid transoid alignment of the catechol ring planes. Vanadium complexes 10a, b exhibit a square-pyramidal coordination sphere with cisoid alignment of the catechol ring planes and evidence for intermolecular pairing via weak VO···Pd contacts in the solid state; complexes 8, 9 do not undergo conformational inversion on the NMR time-scale. The molecular structure of Ti complex 11a is characterized by a different orientation of the catechol moieties, which can be envisaged to picture an intermediate state during a configuration inversion process, and a strong hydrogen bridge between a terminally coordinated catecholato-oxygen atom and a solvent molecule (MeOH). Solution NMR studies indicate that the (MeO)₂Ti(μ-L)₂M' framework is in this case conformationally labile and that the MeO ligands undergo intermolecular dynamic exchange with the solvent. Copyright

Full text of DOI:10.1002/zaac.201300571

ARTICLE
DOI: 10.1002/zaac.201300571
A Ditopic Catechol Phosphane as Building Block for Selective Construction
of Heterometallic Complexes with Early and Late Transition Metal Centers
Gernot Bauer,[a] Daniela Förster,[a] Martin Nieger,[b] and Dietrich Gudat*[a]
Keywords: Phosphane ligands; O ligands; Bridging ligands; Heterometallic complexes; Template synthesis
Abstract. Base-assisted reaction of catechol phosphane 2 (H2L) with with rigid transoid alignment of the catechol ring planes. Vanadium
[MЈCl2(cod)] (cod = 1,5-cyclooctadiene, MЈ = Pd, Pt) yielded chelate complexes 10a,b exhibit a square-pyramidal coordination sphere with
complexes [MЈ(HL)2] (7a,b). Spectroscopic and single-crystal X-ray cisoid alignment of the catechol ring planes and evidence for intermo-
diffraction studies revealed that both complexes feature cis-configura-
tion of the P- and O-donor atoms in solution and in the solid state. 8, 9 do not undergo conformational inversion on the NMR time-scale.
Reaction of 7a,b with acetylacetonato or alkoxide complexes The molecular structure of Ti complex 11a is characterized by a dif-
lecular pairing via weak VO···Pd contacts in the solid state; complexes
[MO2(acac)2] (M = Mo, W), [VO(acac)2], [{Ti(μ-O)(acac)2}2], or ferent orientation of the catechol moieties, which can be envisaged to
Ti(OiPr)4 gave good to excellent yields of early-late heterometallic picture an intermediate state during a configuration inversion process,
complexes [MOn(μ-L)2MЈ] (MOn = MoO2, WO2, VO; 8a,b–10a,b) or and a strong hydrogen bridge between a terminally coordinated cate-
[Ti(RO-1κO)2(μ-l-1κ2O,O’-2κ2P,O)2Pd] (R = Me, iPr; 11a,b), which cholato-oxygen atom and a solvent molecule (MeOH). Solution NMR
were inaccessible via other synthetic routes. Spectroscopic and single- studies indicate that the (MeO)2Ti(μ-L)2M’ framework is in this case
crystal X-ray diffraction studies revealed that the early metal centres
in 8a,b, 9b and in 11b feature distorted octahedral coordination spheres
conformationally labile and that the MeO ligands undergo intermo-
lecular dynamic exchange with the solvent.
Introduction
Functional phosphanes which combine a trivalent phos-
phorus atom with additional, electronically different donor
groups receive persistent and still continuing attention as hy-
brid ligands.[1] A special class of such species are hydroxy-
phosphanes[2] which contain one or more alcoholic or phenolic
OH-functions that may act as neutral or (after deprotonation)
anionic metal binding sites. Coordination of soft (P) and hard
(O) donor moieties can occur to the same metal to give chelate
complexes which may have interesting applications in cataly-
sis.[1,2] Alternatively, the different binding preferences of the
donor functionalities can be used for specific syntheses of
heterometallic complexes with μ-bridging hydroxyphosphane
ligands. In particular, catechol phosphanes like 1 and 2
(Scheme 1) have been employed to obtain supramolecular
architectures[3] or defined complexes like 3[4,5] or 4.[6]
* Prof. Dr. D. Gudat
Fax: +49-71168564241
E-Mail: gudat@iac.uni-stuttgart.de
[a] Institut für Anorganische Chemie
Universität Stuttgart
Scheme 1. MXn = GaCl (3a), SnCl2 (3b), BiCl (3c); MЈ = Ag (4a),
Au (4b).
Pfaffenwaldring 55
70550 Stuttgart, Germany
[b] Laboratory of Inorganic Chemistry
Department of Chemistry (A.I. Virtasen aukio1)
P.O Box 55
The latter compounds can be either generated in one step by
self-assembly from the ditopic ligand 2 and suitable hard and
soft Lewis acids (Scheme 2, reaction (I)), or via a two-step
sequence. In this case, two molecules of 2 are first reacted
with a hard Lewis acid which binds to the catechol units of
00014 University of Helsinki, Finland
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/zaac.201300571 or from the au-
thor.
Z. Anorg. Allg. Chem. 2014, 640, (2), 325–333
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G. Bauer, D. Förster, M. Nieger, D. Gudat
ARTICLE
both reactants and serves thus as a template for the formation
of a bidentate phosphane. Interaction of this preformed ligand
with a soft transition metal centre gives then the final product
(Scheme 2, reactions (II), (III)).[6] It has been shown[5] that the
steric bulk and bite angle of the supramolecular bis-phosphane
unit can be adjusted by choosing different templates, and that
the addition of external donors may induce a change from a
tetradentate O2P2- to a bidentate P2-coordination mode. The
potential for applications in catalysis was illustrated by the use
of 3b as catalyst in the Sonogashira coupling of p-iodonitro-
benzene with phenyl acetylene.[4],[5]
Results and Discussion
Initial attempts to prepare heterometallic complexes of the
type [(MXn(μ-L)2MЈ] (LH2 = 2; X = anionic ligand, MЈ = Pd,
Pt; M = TiIV, VIV, MoVI) via self-assembly of 2 and simple
hard and soft metal complex precursors in a single synthetic
step[4,5] gave no satisfactory results. ESI-MS studies of crude
reaction products indicated that mixtures of oligomeric aggre-
gates of unknown overall composition had formed which could
not be further separated or successfully purified. As analysis
of isotope patterns implied that the M:MЈ:L ratios of individual
species varied and differed from the stoichiometric ratio of the
reactants, we assume that uncontrolled condensation reactions
had taken place. In order to avoid the complications associated
with a multi-component reaction, we next attempted a stepwise
synthesis of the target compounds[6] via initial reaction of 2
with a suitable early transition metal template and subsequent
quenching with [MЈCl2(cod)] (MЈ = Pd, Pt; reactions (II), (III)
in Scheme 2). Reaction monitoring (ESI-MS, 31P NMR) indi-
cated that the first step was likewise unspecific, and the whole
two-step sequence gave similar results as the self-assembly ap-
proach. As a final alternative, we decided to explore stepwise
construction of heterometallic complexes by a reversed reac-
tion sequence, first converting 2 with an appropriate Pd (or
Pt) precursor into a mononuclear complex with P,O-chelating
catechol phosphanes (reaction (IV), Scheme 2) which may
then react with a suitable early transition metal substrate to
give the final product (reaction (V), Scheme 2). The rationale
behind this approach lies in using the mononuclear, kinetically
rather inert and rigid P,O-chelates as templates which allow to
pre-organize the remaining OH-functionalities and exert con-
trol on the subsequent condensation step.
Scheme 2. Reaction pathways for the assembly of heterobimetallic
complexes 3 (MXn = e.g. GaCl, SnCl2, BiCl; MЈ = Pd, Pt; X = anionic
ligand, e.g. halide; cod = 1,5-cyclooctadiene).
The required P,O-chelates 7a,b are readily available by treat-
ing phosphane complexes 6a,b[9] or 2:1 mixtures of 2 and
[MЈCl2(cod)] (MЈ = Pd, Pt) with excess triethylamine in EtOH
solution (Scheme 3).
Although most existing examples of complexes 3, 4 have
been assembled on main group element templates (B, Ga, Sn,
Bi), the synthesis of zirconium complex 5[5] gave a first indica-
tion that hard transition metal Lewis acids can likewise be in-
corporated, and suggested that catechol phosphane 2 might be
more generally applicable as scaffold for the controlled as-
sembly of early-late heterometallic transition metal com-
plexes.[7] Species of this type are distinguished by close prox-
imity of two transition metal centres with different chemical
properties whose communication can induce a modification of
the specific behaviour of the individual metal atoms (“coopera-
tive interaction") and may thereby enable stoichiometric or
catalytic transformations that are unavailable for analogous
monometallic complexes.[7,8] In order to probe the scope of
this approach, we decided to study the prospect of employing
2 for the synthesis of dinuclear complexes featuring a PdII or
PtII atom as late transition metal and an early transition metal
atom from groups 4–6 (M = Ti, V, Mo, W) that may carry
additional functional ligands and can give rise to further reac-
tivity. Our first efforts aimed at the synthesis of oxo complexes
with M(O) or M(O)2 units, or of complex alkoxide featuring
M(OR) moieties.
Scheme 3. Synthesis of chelate complexes 7a,b (cod = 1,5-cyclooc-
tadiene) and early/late heterometallics 8a,b–11a,b. Reaction condi-
tions: (I) [MЈCl2(cod)], – cod; (II) 2 Et3N, – 2 Et3NHCl; (III)
[MO2(acac)2], – 2 acacH; (IV) [VO(acac)2], – 2 acacH; (V) 0.5 [{Ti(μ-
O)(acac)2}2] / 2 MeOH or Ti(OiPr)4, – 2 acacH / H2O or – 2 iPrOH.
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Ditopic Catechol Phosphane as Building Block for Heterometallic Complexes
1
Reaction monitoring by 31P NMR spectroscopy gave no evi-
Solution 31P and H NMR spectra of 7a,b display a single
dence for the formation of by-products, and indicates that the line or a single set of resonances, respectively, which indicates
conversion is quantitative. The sparingly soluble products pre- the prevalence of a single, configurationally stable isomer. The
1
cipitate and are easily isolated in excellent yield after simple magnitude of J(195Pt,P) = 3925 Hz for 7b and the observed
1
filtration and washing with EtOH. Attempts to prepare an anal- broad doublet structure of the H NMR signal of the benzylic
ogous nickel complex remained unsuccessful.
protons in both compounds are characteristic for a cis complex
The complexes 7a,b were unambiguously identified by ana- (the benzylic protons in a trans complex are expected to give
lytical and spectroscopic data as well as XRD studies of iso- rise to a signal with pseudo-triplet rather than doublet struc-
typic single-crystals of solvates that had been obtained by ture[10]) and suggest that the cis-configuration, which had been
crystallization from CHCl3. Both solvates contain two mole- established in the solid state, is conserved in solution. Even if
cules of CHCl3 that interact via weak C–H···O hydrogen brid- the precise reason for this preference remains in the dark, it is
ges with the hydroxyl oxygen atoms. The metal atoms in both considered fortuitous as it should facilitate the intended con-
complexes exhibit the expected square-planar coordination ge- densation of 7a,b with early transition metal substrates.
ometry with cis-arrangement of P- and O-donor atoms (Fig-
In line with this assumption, 7a,b react with [MO2(acac)2]
ure 1; important bond lengths and angles are listed in Table 1). (M = Mo, W) at ambient temperature in CH2Cl2 under cleav-
The six-membered chelate rings are puckered, and the free age of acetylacetone to yield heterometallic complexes 8a,b
OH-group in each catechol unit exhibits an intramolecular hy- and 9a,b (Scheme 3), respectively. The products separated
drogen bond to the metal-bound oxygen atom in the same ring. from the reaction mixture as deep red (8a), orange (8b, 9a), or
The remaining metric parameters are unpeculiar.
pale yellow (9b) microcrystalline solids, and were isolated in
good yield by filtration. By analogy, treatment of 7a,b with
[VO(acac)2] gave binuclear oxovanadyl complexes 10a,b
which were isolated after a similar work-up procedure. Reac-
tion of 7a with [{Ti(μ-O)(acac)2}2] under similar conditions
was sluggish, but a clean reaction was observed in MeOH at
50 °C. Partial removal of the solvent under vacuum and
crystallization of the residue at 4 °C allowed us to isolate a
red, crystalline solid which was subsequently identified as
mixed Pd,Ti methoxide 11a (Scheme 3); formation of this
product is readily explained as resulting from methanolysis of
[{Ti(μ-O)(acac)2}2] and condensation with 7a under cleavage
of acetylacetone. The homologous complex 11b was readily
obtained via transalcoholysis between 7a and Ti(OiPr)4 in
iPrOH solution. Attempts to prepare a heterometallic chloro-
titanium complex via base induced condensation of 7a and
TiCl4 gave inconclusive results, which is in marked contrast to
the clean synthesis of the trinuclear Zr,Pd complex 5[5] via
base-induced condensation from ZrCl4.
Complexes 8–11 are air and moisture stable, yellow to deep
red, crystalline solids which were unambiguously identified by
analytical and spectroscopic data; all species except 9a were
further characterized by single-crystal XRD studies. The
molybdenum and tungsten complexes exhibit rather high ther-
mal stability and decompose only above 250 °C (8a,b) or
400 °C (9a,b), respectively. The Pd, V- and Pd, Ti complexes
10, 11 exhibit reasonable solubility in polar organic solvents
whereas dioxo complexes 8, 9 are at best sparingly soluble in
non-coordinating solvents like CHCl3, and dissolve readily
only in strong donor solvents such as DMF or DMSO. The
solubility decreases generally from Mo to W and from Pd to
Pt complexes.
Figure 1. Molecular structure of 7a in the crystal. Thermal ellipsoids
are drawn at 50% probability level; hydrogen atoms of CH bonds are
omitted for clarity. Symmetry dependent atoms were generated with
the operator 1–x, y, 1.5–z). Intramolecular OH···O hydrogen bonds are
drawn as dashed lines.
Table 1. Selected bond lengths (in Å) and angles (in °) for 7a,b.
7a
7b
M(1)–O(1)a)
M(1)–P(1)a)
2.0457(13)
2.2441(5)
2.049(2)
2.2272(7)
Complexes 8, 9, and 11 are diamagnetic and exhibit well
1
resolved H and 31P NMR spectra. The 31P coordination shifts
O(1)–M(1)–O(1Ј)
O(1)–M(1)–P(1)a)
P(1Ј)–M(1)–P(1)
80.45(7)
90.63(4)
98.67(3)
169.77(4)
360.4(2)
78.76(12)
91.21(6)
99.25(4)
168.61(6)
360.4(2)
which accompany the transition from mono- to binuclear com-
plexes are very small for the Pd,Ti complexes 11a,b (Δδ31P =
+4) and increase in 8a,b and 9a,b; Pd-containing complexes
8a, 9a show somewhat larger shifts (Δδ31P = +16) than their
Pt-containing analogues 8b, 9b (Δδ31P = +10). The magni-
O(1)–M(1)–P(1Ј)a)
Sum of bond angles at M
a) Both M–O and M–P bonds and P–M–O angles are identical due to
crystallographic C2-symmetry.
Z. Anorg. Allg. Chem. 2014, 325–333
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327

G. Bauer, D. Förster, M. Nieger, D. Gudat
ARTICLE
tudes of 1J(195Pt,P) in 8b (4165 Hz) and 9b (4192 Hz) are dimers (cf. the discussion of the crystal structures of 10a,b
1
slightly larger than in 7b. The appearance of two separate H further below) which are formed by aggregation and coexist
NMR signals for the benzylic protons in the catechol phos- with the paramagnetic monomers. No efforts to further eluci-
phane ligands of 8a,b and 9a,b indicates the presence of non- date these phenomena were undertaken.
planar six-membered chelate rings which do not undergo ring
The single-crystal XRD studies revealed that complexes 8a
inversion on the NMR time scale. The benzylic protons in and 9b crystallized as solvates with one (8a) or two (9b) mole-
11a,b give rise to a single, broadened, multiplet which suggests cules of acetonitrile that interact via weak C-H···O hydrogen
that the chelate rings in these complexes are more flexible. In bridges with the polar metal-oxo units. The crystals of 8b are
the case of 11a, the methyl protons of the two alkoxide ligands free of solvent and contain isolated molecules which lack any
and the additional solvent molecule give rise to a single reso- particular intermolecular interactions. The individual mole-
nance, which reveals that rapid dynamic exchange between co- cules in all three crystals exhibit very similar structural fea-
ordinated methoxides and free MeOH takes place.
tures (the molecular structure of 8a is displayed in Figure 2,
The vanadyl complexes 10a,b are paramagnetic. Room tem-
perature EPR spectra show a strong signal with a splitting aris-
ing from hyperfine interaction with the 51V nucleus (100%
nat. abundance, I = 7/2). The g-factors (10a: 1.980; 10b:
1.984) and the magnitude of the hyperfine coupling constant
(a(51V) = 87 · 10–4 cm–1 in both complexes) are slightly
smaller than in other oxovanadium(IV) acetylacetonates with
d1 electron configuration.[11] The failure to resolve any further
hyperfine interactions strongly suggests that the unpaired elec-
tron is mainly metal centered. Whereas 1H NMR spectroscopic
studies of both complexes gave no conclusive results (which
is not unexpected in regard of their paramagnetic nature), the
31P NMR spectra showed broadened signals at similar chemi-
cal shifts as had been observed for 8, 9 (δ31P = 77 (10a), 31
(10b)). The absence of any substantial paramagnetically in-
duced chemical shift changes indicates that the (pseudo)con-
tact interaction between the phosphorus atom and the paramag-
netic center may either incidentally vanish (due to a special
alignment of the V-P vectors relative to the principal magnetic
Figure 2. Molecular structure of 8a in the crystal. Thermal ellipsoids
are drawn at 50% probability level; hydrogen atoms are omitted for
axis of the molecule), or that the signals arise from EPR-silent clarity.
Table 2. Selected bond lengths (in Å) and angles (in °) for 8a,b, 9b, 10a,b, 11a,b.
8a
8b
9b
10aa)
10ba)
11a
11bb)
MЈ
M
Pd
Mo
Pt
Mo
Pt
W
Pd
V
Pt
V
Pd
Ti
Pd
Ti
MЈ–O(1)
MЈ–O(20)
MЈ–P(1)
2.076(2)
2.094(2)
2.249(1)
2.257(1)
1.701(2)
1.703(2)
1.991(2)
1.995(2)
2.212(2)
2.293(2)
3.455(1)
2.0828(12)
2.0897(12)
2.2386(5)
2.2336(5)
1.7003(13)
1.6998(14)
1.9839(13)
1.9893(14)
2.2868(12)
2.2861(12)
3.4897(6)
2.0678(16)
2.0750(17)
2.2253(6)
2.2308(6)
1.7124(18)
1.7192(18)
1.9786(17)
1.9947(17)
2.2481(17)
2.2731(17)
3.4887(3)
2.088(7)
2.061(7)
2.252(3)
2.246(3)
1.580(9)
–
1.937(9)
1.950(8)
2.026(8)
2.003(7)
3.174(2)
2.082(10)
2.014(9)
2.211(4)
2.234(4)
1.590(11)
–
1.944(10)
1.910(11)
2.042(10)
2.004(9)
3.166(3)
2.102(2)
2.036(2)
2.239(1)
2.238(1)
1.799(2)
1.830(2)
1.929(2)
2.033(2)
2.111(2)
2.120(2)
3.246(1)
2.076(4)
2.087(4)
2.259(2)
2.261(2)
1.804(4)
1.799(4)
1.976(5)
1.983(5)
2.161(4)
2.237(4)
3.323(2)
MЈ–P(2)
M–O(1A)c,d,e)
M–O(1B)d,e)
M–O(21)
M–O(2)
M–O(1)
M–O(20)
M···MЈ
O(1)–MЈ–O(20)
O(1)–MЈ–P(1)
O(20)–MЈ–P(2)
P(1)–MЈ–P(2)
O(1A)–M–O(1B)
O(21)–M–O(20)
O(1)–M–O(20)
O(2)–M–O(1)
77.7(1)
90.9(1)
92.3(1)
99.12(3)
107.4(1)
74.3(1)
71.0(1)
75.1(1)
78.15(5)
91.50(4)
91.35(4)
99.15(2)
107.10(7)
74.22(5)
70.22(4)
74.27(5)
76.49(7)
91.32(5)
92.30(5)
99.93(2)
106.98(9)
74.53(7)
69.11(6)
73.80(6)
75.7(3)
92.2(2)
91.4(2)
100.7(1)
–
81.9(3)
78.4(3)
81.8(3)
76.5(4)
92.3(3)
90.5(3)
100.93(14)
–
81.7(4)
77.6(4)
81.5(4)
77.33(8)
90.52(6)
91.74(6)
101.90(3)
96.64(10)
77.27(9)
75.33(8)
76.62(8)
80.0(2)
89.0(1)
89.7(1)
101.3(1)
104.3(2)
76.54(16)
74.92(15)
77.04(17)
a) Only data for the “non-associated” molecule; a complete listing of all data for all three crystallographically independent molecules is included
as SI. b) Only one of two crystallographically independent molecules; the data for both species is included as SI. c) Atomic label O1V for
10a,b. d) atomic labels O1M, O2M for 11a. e) Atomic labels O39, O42 for 11b.
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Ditopic Catechol Phosphane as Building Block for Heterometallic Complexes
those of 8b and 9a are included in the Supporting Information)
and show no significant deviations in bond lengths and angles
(Table 2).
Further distortions of the MO6-octahedra in 8a,b and 9b
result from a bend in the “axis“ connecting the metal atom
with the terminal catecholate oxygen atoms O2, O21
(O2–M–O21 161–165°), and a strong tilt of the metal-dioxo
unit relative to the central MO2M’ ring (tilt angles between
O1B–M–O1A and O1–M–O20 planes 17.8–21.4°). These fea-
tures are obviously imposed by the geometrical constraints of
the chelate ligands which are also held responsible for the fact
that the μ-bridging oxygen atoms O1, O20 adopt pyramidal
rather than the commonly observed trigonal planar coordina-
tion. The catechol rings are therefore not coplanar with the
central ring, but adopt a marked trans-bent alignment. Similar
structural distortions had been observed for the tin atoms in
3.[4,5] The M–O distances fall into three clearly distinct ranges
Figure 3. Molecular structure of the “isolated” one (without intermo-
lecular VO···Pd contacts) of three crystallographically independent
molecules of 10a in the crystal. Thermal ellipsoids are drawn at 50%
probability level, and hydrogen atoms are omitted for clarity.
which are associated with bonding of the metal atom to the
oxo ligand (M–O 1.70–1.71 Å) as well as bridging (M–O
2.21–2.29 Å) and terminally coordinated (M–O 1.98–2.00 Å)
catechol oxygen atoms.
The vanadyl complexes 10a,b crystallize as solvates which Figure 3 and Table 3) exhibit only weak, unspecific CH···Cl or
contain an array of three crystallographically independent mo- CH···O hydrogen bridge interactions to adjacent molecules.
lecular complexes and solvent molecules (CH2Cl2, CHCl3).
The two remaining complex entities are weakly associated
The asymmetric unit of the elementary cell contains in case of via a pair of short intermolecular MЈ···O contacts (10a:
10a four molecules of CHCl3 and in case of 10b six molecules Pd1(A)–O1V(C) 3.024(10), Pd1(C)–O1V(A) 2.689(8) Å; 10b:
of CH2Cl2 (of which four totally disordered molecules were Pt1–O3(B) 3.082(10), Pt1(B)–O3 3.120(10) Å] which are
removed using SQUEEZE[12]). The solvent molecules and one markedly shorter than the sum of the van-der-Waals radii
of the three complexes (10a: molecule B; 10b: molecule A, see (Pd···O 3.65 Å, Pt···O 3.79 Å[13]) but do not induce significant
Table 3. X-ray details for 7a,b, 8a,b, 9b.
7a
7b
8a
8b
9b
Empirical formula
C38H32O4P2Pd
·2CHCl3
959.71
C38H32O4P2Pt
·2CHCl3
1048.40
C38H30MoO6P2Pd
·CH3CN
887.95
C38H30MoO6P2Pt
C38H30O6P2PtW
·2CH3CN
1105.61
Formula weight /g mol–1
T /K
935.59
123(2)
123(2)
123(2)
123(2)
123(2)
Crystal size /mm
0.35 ϫ 0.20 ϫ 0.10 0.30 ϫ 0.10 ϫ 0.05 0.18 ϫ 0.12 ϫ 0.06 0.30 ϫ 0.15 ϫ 0.10 0.16 ϫ 0.10 ϫ 0.08
crystal system
space group
a /Å
b /Å
c /Å
α /°
β /°
monoclinic
C2/c (No.15)
13.848(1)
28.665(2)
11.434(1)
monoclinic
C2/c (No. 15)
13.864(2)
28.702(4)
11.429(1)
monoclinic
P21/n (No.14)
18.725(1)
10.391(1)
19.739(1)
triclinic
P1 (No.2)
monoclinic
P21/n (No.14)
11.2931(7)
17.2776(3)
19.4364(15)
¯
10.434(1)
10.784(1)
16.890(1)
82.00(1)
77.33(1)
62.81(1)
1647.6(2)
2
116.05(1)
116.21(1)
114.46(1)
100.306(6)
γ /°
V /Å3
4077.7(5)
4
1.563
4080.3(9)
4
1.707
3495.9(4)
4
1.687
3731.2(4)
4
1.968
Z
Dc /Mg·m–3
1.886
4.767
μ /mm–1
0.967
3.951
1.015
6.964
F(000)
1936
2064
1784
912
2128
2θmax. /°
55
55
55
55
55
Reflections collected
Unique reflections
Rint
47694
4678
0.038
46840
4671
0.054
22097
7985
0.039
38161
7533
0.020
53995
8540
0.029
max./ min. transmission
Data/restraints/parameters
G.o.F. on F2
R1 [I Ͼ 2 σ(I)]
wR2 (F2)
0.9010 / 0.7415
4678 / 1 / 243
1.04
0.026
0.059
0.8372 / 0.4616
4671 / 1 / 243
1.08
0.026
0.065
0.9422 / 0.8218
7985 / 0 / 461
1.04
0.035
0.066
0.6468 / 0.4225
7533 / 0 / 433
1.06
0.013
0.031
0.5949 / 0.4539
8540 / 0 / 489
1.07
0.018
0.038
Largest diff. peak/hole /e·Å–3
0.663 / –0.603
2.285 / –0.974
0.576 / –0.487
0.492 / –0.511
0.530 / –0.487
Z. Anorg. Allg. Chem. 2014, 325–333
© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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329

G. Bauer, D. Förster, M. Nieger, D. Gudat
ARTICLE
distortions of bond lengths or angles (data listed in the SI). vs. 0.73–0.74 for MoVI, WVI). The Ti–O distances involving
Similar contacts to axially coordinated molecules have pre- alkoxide ligands (1.80–1.83 Å) lie in the normal range of stan-
viously been observed for other square-planar PdII com- dard bond lengths (Ti–O 1.847Ϯ0.055 Å[14]).
plexes,[13] and we tentatively explain their presence as a conse-
Complex 11a crystallizes as solvate with a molecule of
quence of electrostatic interaction between the negatively methanol which forms a strong OH···O hydrogen bond (dis-
charged oxo ligand with the positively charged metal atom of tance O2···O3M 2.698(3) Å) to a terminally coordinated cate-
the neighboring molecule.
cholato-oxygen atom. The molecular structure of the complex
The square-planar coordination at M’ is similar as in 8a,b itself deviates from that of 11b in showing a different confor-
and 9a,b, but the four-membered MЈO2V rings (M’ = Pd, Pt) mational disposition of the two catechol units in the octahedral
are no longer planar but slightly folded along the O···O axis. coordination sphere of Ti (Figure 4): in contrast to 11b and 8,
This folding together with the square-pyramidal coordination 9, where the of terminal and bridging oxygen atoms of the
sphere at V and the cisoid bending of the catechol rings with two chelating catecholates occupy mutual trans-positions, the
respect to the central MЈO2V ring match appropriate features terminal O21 atom is now trans to the bridging O1 atom of
of the five-coordinate Ga atom in 3a,[5] which seems natural the second catecholate, and the coordination site trans to the
in view of the like coordination geometries and similar ionic second terminal oxygen atom O2 is occupied by the O1M atom
radii of five-coordinate GaIII (0.69 Å) and VIV (0.67 Å). The of a methoxide. As an immediate consequence, the coordina-
V–O distances to oxo ligands (V–O 1.58–1.61 Å) are again tion environment at one of the bridging oxygen atoms is flat-
clearly shorter than those to catecholato-oxygen atoms, but the tened (sum of bond angles 346° at O20 vs. 320° at O1), and
difference between terminal (V–O 1.94–1.96 Å) and bridging one catechol ring is nearly coplanar to the “equatorial“ plane
(V–O 1.99–2.03 Å) V–O(catecholate) bonds is less pro- of the Ti coordination polyhedron as defined by the atoms O1,
nounced than in 8, 9. The decrease in the MЈ···M distance from O20, O21, and O2M (Figure 4). Further features are a slight
8, 9 (3.44–3.49 Å) to 10a,b (3.15–3.19 Å) can be related to folding of the central TiO2Pd ring and a twist of 13.4° between
the geometrical constraints imposed by the smaller radius of the P1,Pd1,P2 and O1,Pd1,O20 planes, which results in a per-
the metal M (0.67 Å for five-coordinate VIV vs. 0.73–0.74 Å ceptible tetrahedral distortion of the square-planar coordination
for six-coordinate MoVI and WVI, respectively) and the folding geometry at Pd. The Ti1–O2 bond involved in the hydrogen
of the MO2M’ ring in 10a,b.
bridging with the additional solvent molecule is 0.1 Å longer
Crystals of Ti complex 11b contain two crystallographically (2.033(2)) than the non-interacting terminal Ti1–O21 bond
independent molecular complexes which differ merely in the (1.929(3) Å).
orientation of the peripheral iPr-groups (see Figure 4 for a dis-
The structural disposition of 11a seems remarkable as it is
play of one conformer). The metal coordination environments not only unprecedented for heterometallics of the type
correspond in both their qualitative (distorted octahedral and [MX2(μ-L)2MЈ],[4–6] but has also implications for the inter-
square-planar coordination at Ti and Pd, planar TiO2Pd ring) pretation of the dynamics and reactivity of these species: 11a
and quantitative features (cf. listing of relevant bond lengths can be envisaged to represent an intermediate step in the
and angles in Table 2) closely to those in 8a,b, which we attri- epimerization of one conformer with transoid alignment of the
bute to the fortuitous match of the ionic radii (0.745 Å for TiIV catecholate-groups (as in 8, 9, 11b) into its mirror image, and
Figure 4. Molecular structure of 11a·MeOH (right) and one of two crystallographically independent molecules of 11b (left) in the crystal.
Thermal ellipsoids are drawn at 50% probability level; hydrogen atoms of CH bonds are omitted for clarity. Intermolecular OH···O hydrogen
bonds are drawn as dashed lines. Intermolecular hydrogen bond for 11a: O(3M)–H(3M) 0.85(2), H(3M)..O(2) 1.86(2), O(3M)..O(2) 2.698(3) Å,
O(3M)–H(3M)..O(2) 165(5)°.
330
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© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2014, 325–333

Ditopic Catechol Phosphane as Building Block for Heterometallic Complexes
referenced to external TMS (1H), 85% H3PO4 (Ξ = 40.480 747 MHz,
its existence may help to rationalize the low configurational
stability that had previously been observed for related com-
plexes.[4,5] Since the M–O bond lengthening associated with
formation of a hydrogen bond to a protic solvent releases not
only the geometric constraints but should also facilitate a sub-
sequent proton transfer and concomitant ligand dissociation,
hydrogen bonding interactions may be considered to assist not
only the equilibration of different conformers leading to race-
mization, but also to facilitate intermolecular ligand exchange
in solution, and their participation offers a consistent mechan-
istic explanation for these processes.
31P). Coupling constants are given as absolute values. ESI mass spectra
in positive or negative ion mode were recorded in MeOH solution with
a Bruker Daltonics MicroTOF Q instrument. Elemental analyses were
determined on a Perkin–Elmer 24000CHN/O Analyzer. Melting points
were determined in sealed capillaries with a Büchi B-545 melting point
apparatus. EPR spectra were measured with a Bruker EMX X-band
spectrometer. Hyperfine coupling constants and g-factors were deter-
mined from spectral simulation. Catechol phosphane 2 was prepared
as described previously.[9]
Complex 7a: [PdCl2(cod)] (965 mg, 3.40 mmol) and triethylamine
(1.2 mL, 8.6 mmol) were added to a solution of 2 (2.10 g, 6.80 mmol)
in EtOH (35 mL). The mixture was stirred for 1 h. The orange precipi-
tate formed was collected by filtration, washed with a small portion of
EtOH, and dried under vacuum to give 2.38 g (3.30 mmol, yield 97%)
of product, m.p. 215 °C. Single crystals suitable for XRD studies were
obtained by recrystallization from CHCl3. – (+)-ESI-MS: m/e =
721.09 [M + H+], 743.08 [M + Na+]. 1H NMR (CDCl3): δ = 7.52 (br.
Conclusions
Reaction of catechol phosphane 2 (H2L) with palladium and
platinum acetate gave high yields of complexes [MЈ(HL)2]
(7a,b; MЈ = Pd, Pt). Spectroscopic and structural characteriza-
tion established a κ2P,O-chelating coordination of the bidentate
ligands and a cis-configuration of P- and O-donor atoms at the
metal atom that is stable in both solution and solid state. Fur-
ther condensation with acetylacetonates [MO2(acac)2] (M =
Mo, W) or [MO(acac)2] (M = V, Ti) or metal alkoxides
(Ti(OiPr)4) produced dinuclear complexes [MXn(μ-l-1κOO’-
2κPO)2MЈ] (MXn = MoO2, WO2, VO, Ti(OR)2, 8–11) which
were not accessible via other routes. The highly specific for-
mation of these products demonstrates the ability of 7a,b to
act as template for the synthesis of early-late heterometallics
with additional functional oxo or alkoxide moieties, and should
stimulate studies aiming to extend this approach to include fur-
ther, yet unexplored combinations of different transition metals
or functional ligands. Crystallographic and spectroscopic stud-
ies revealed that the majority of newly synthesized complexes
exhibit rigid molecular structures which match those of pre-
viously known complexes [ECln(μ-L)2MЈ] (MЈ = Pd, Pt; E =
Ga, Sn, Bi) and are likewise characterized by a certain steric
strain in the polycyclic ligand skeleton. The deviating confor-
mational disposition of the bridging catecholate units and the
interaction with a solvent molecule via an OH···O hydrogen
bridge in the case of 11a are unprecedented features which
imply that hydrogen bonding (and possibly proton transfer pro-
cesses) can facilitate racemization of the chiral metal coordina-
tion sphere and intermolecular ligand exchange of binuclear
complexes [ECln(μ-L)2MЈ], and offer thus a mechanistic ex-
planation for the frequently observed dynamic behaviour in
solution.
3
s, 2 H, OH), 7.23– 6.97 (m, 20 H, Ph), 6.76 (d, JHH = 7.7 Hz, 2 H,
3
3
C6H3), 6.26 (t, JHH = 7.8 Hz, 2 H, C6H3), 6.06 (d, JHH = 7.7 Hz, 2
H, C6H3), 3.38–3.26 (m, 4 H, CH2). 31P{1H} NMR (CDCl3): δ = 61.9
(s). C38H32O4P2Pd·2EtOH (813.18): calcd. C 62.04, H 5.45, found C
1
61.86, H 5.32; the presence of the residual solvent was verified by H
NMR spectroscopy.
Complex 7b: [PtCl2(cod)] (1.65 g, 2.67 mmol) and triethylamine
(0.9 mL, 6.6 mmol) were added to a solution of 2 (1.00 g, 5.34 mmol)
in EtOH (40 mL). The mixture was stirred for 24 h. The formed light
yellow precipitate was collected by filtration, washed with a small
portion of EtOH, and dried under vacuum to give 2.30 g (2.51 mmol,
yield 94%) of product, m.p. 327 °C. Single crystals suitable for XRD
studies were obtained by recrystallization from CHCl3. – (+)-ESI-MS:
m/e = 810.14 [M + H+], 832.13 [M + Na+]. 1H NMR (CDCl3): δ =
7.54 (br. s, 2 H, OH), 7.23–7.12 (m, 12 H, Ph), 7.10–7.00 (m, 8 H,
3
3
Ph), 6.77 (d, JHH = 7.7 Hz, 2 H, C6H3), 6.25 (t, JHH = 7.8 Hz, 2 H,
3
2
3
C6H3), 5.96 (d, JHH = 7.7 Hz, 2 H, C6H3), 3.43 (d, JPH = 11.6, JPtH
= 39 Hz, 4 H, CH2). 31P{1H} NMR (CDCl3): δ = 30.7 (s, JPtP
1
=
3925 Hz). C38H32O4P2Pt (809.14): calcd. C 56.37, H 3.98, found C
55.99, H 4.57.
Complex 8a: [MoO2(acac)2] (108 mg, 331 μmol) was added to a solu-
tion of 7a (240 mg, 332 μmol) in CH2Cl2 (20 mL). The mixture was
stirred for 3 h. The red precipitate formed was collected by filtration
and dried under vacuum. The filtrate was concentrated to approx. one
third of its original volume and stored overnight at 4 °C to give an
additional crop of crystalline precipitate. The combined product frac-
tions were recrystallized from acetonitrile. Yield 235 mg (277 μmol,
1
83%); m p. Ͼ 250 °C (dec.). H NMR ([D6]acetone): δ = 7.62–7.25
(m, 8 H, o-Ph), 7.09–6.87 (m, 12 H, m-/p-Ph), 6.61 (d, 3JHH = 7.8 Hz,
2 H, C6H3), 6.44 (t, 3JHH = 7.8 Hz, 2 H, C6H3), 6.02 (d, 3JHH = 7.8 Hz,
2
2
2 H, C6H3), 3.95 (dm, JPH = 12.2 Hz, 2 H, CH2), 3.35 (dm, JHH
=
17.0, JPH = 11.9 Hz, 2 H, CH2). 31P{1H} NMR ([D6]acetone): δ =
77.4 (s). – (+)-ESI-MS: m/e = 848.97 [M + H+], 870.95 [M + Na+].
C38H30O6P2PdMo (846.95): calcd. C 53.89, H 3.57, found C 53.78, H
3.53.
2
Experimental Section
Complex 8b: The complex was prepared from 7b (122 mg, 150 μmol)
and [MoO2(acac)2] (49 mg, 150 μmol) using the procedure described
General Procedures
All manipulations were carried out under an atmosphere of dry argon for 8a. Yield 110 mg (117 μmol, 78%), m.p. Ͼ250 °C (dec.). 1H NMR
using standard vacuum line techniques. Solvents were dried by stan-
(CDCl3/[D6]DMSO): δ = 7.39–7.28 (m, 6 H, Ph), 7.22–7.13 (m, 6 H,
3
dard procedures. NMR spectra were recorded with Bruker Avance 400 Ph), 6.92–6.84 (m, 4 H, Ph), 6.82–6.74 (m, 4 H, Ph), 6.64 (d, JHH
=
(1H, 400.1 MHz; 31P, 161.9 MHz) and Avance 250 (1H, 250.1 MHz; 7.9 Hz, 2 H, C6H3), 6.47 (t, JHH = 7.7 Hz, 2 H, C6H3), 5.94 (d, JHH
3
3
31P, 101.2 MHz) NMR spectrometers at 303 K; chemical shifts are = 7.5 Hz, 2 H, C6H3), 5.44 (s, 2 H, CH2Cl2), 3.94 (dd, JPH = 7.2,
2
Z. Anorg. Allg. Chem. 2014, 325–333
© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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331

G. Bauer, D. Förster, M. Nieger, D. Gudat
ARTICLE
3
2JHH = 11.9 Hz, 2 H, CH2), 3.15 (t, 3JPH ≈ 2JHH ≈ 12.6 Hz, 2 H, CH2). 3JHH = 7.7 Hz, 2 H, C6H3), 5.98 (d, JHH = 7.7 Hz, 2 H, C6H3), 3.43
31P{1H} NMR (CDCl3/[D6]DMSO): δ = 40.1 (s, JPtP = 4165 Hz). – (s, 9 H, OCH3 of 11a and MeOH), 3.29 (br. m, 4 H, CH2). 31P{1H}
1
(+)-ESI-MS: m/e
=
937.03 [M
+
H+], 959.01 [M
+
Na+].
NMR (CD2Cl2): δ = 65.0 (s). (–)-ESI-MS: m/e = 782.01
C38H30O6P2PtMo·CH2Cl2 (1020.54): calcd. C 45.90, H 3.16, found C [C38H29O5P2PdTi]–, 828.05 [M – H+]–. C40H36O6P2PdTi·CH3OH
45.92, H 3.11%.
(860.99): calcd. C 57.19, H 4.68, found C 56.76, H 4.62.
Complex 9a: [WO2(acac)2] (46 mg, 12 μmol) was added to a solution
of 7a (87 mg, 12 μmol) in CH2Cl2 (12 mL). The mixture was stirred
for 12 h. The formed precipitate was collected by filtration and dried
under vacuum to give 51 mg (5.4 μmol, 45%) of product, m.p.
Ͼ 400 °C (dec.). 1H NMR ([D6]DMSO/[D6]acetone): δ = 7.59–7.26
Complex 11b: The dark red complex was prepared from 7a (181 mg,
250 μmol) and Ti(O iPr)4 (74 μL, 71mg, 250 μmol) in iPrOH (22 mL)
using the procedure described for 11a. Yield 166 mg (188 μmol, 72%),
1
m.p. 185 °C. H NMR (CD2Cl2): δ = 7.38–7.28 (br., 4 H, Ph), 7.19–
3
4
7.05 (br., 16 H, Ph), 6.58 (dd, JHH = 7.9, JHH = 1.0 Hz, 2 H, C6H3),
6.43 (t, 3JHH = 7.7 Hz, 2 H, C6H3), 5.98 (dt, 3JHH = 7.5, 4JHH = 0.9 Hz,
2 H, C6H3), 3.98 (sept, 3JHH = 6.1 Hz, 2 H, OCH), 3.29 (m, 4 H, CH2),
1.18 (d, 3JHH = 6.1 Hz, 12 H, CH3). 31P{1H} NMR (CD2Cl2): δ = 65.0
3
(m, 8 H, o-Ph), 7.08–6.87 (m, 12 H, m/p-Ph), 6.65 (d, JHH = 7.9 Hz,
2 H, C6H3), 6.45 (t, 3JHH = 7.9 Hz, 2 H, C6H3), 5.98 (d, 3JHH = 7.6 Hz,
2
2
2 H, C6H3), 4.05 (dm, , JPH = 12.5 Hz, 2 H, CH2), 3.40 (dm, JPH
=
12.5 Hz, 2 H, CH2). – 31P{1H} NMR ([D6]DMSO/[D6]acetone): δ =
78.1 (s). – (+)-ESI-MS: m/e = 935.01 [M + H+], 957.00 [M + Na+].
C38H30O6P2PdW (934.85): calcd. C 48.82, H 3.23, found C 48.62, H
3.18.
(s). (+)-ESI-MS: m/e
=
783.02 [C38H31O5P2PdTi+], 797.03
[C38H30O5P2PdTi+Na+],
1567.02
[C39H33O5P2PdTi]+,
804.99
[C76H61O10P4Pd2Ti2+]. C44H44O6P2PdTi (885.05): calcd. C 59.71, H
5.01, found C 59.69, H 5.10.
Complex 9b: The light yellow complex was prepared from 7b
(160 mg, 200 μmol) and [WO2(acac)2] (83 mg, 200 μmol) using the
Crystallography: Crystal structures were determined with a Bruker-
procedure described above for 9a. Yield 194 mg (190 μmol, 95%); Nonius KappaCCD diffractometer (7a, 7b, 8a, 8b, 9b, 10a, 10b, 11a)
m.p. Ͼ 400 °C (dec.). 1H NMR ([D6]acetone): δ = 7.47–7.33 (m, 6 H, or a Bruker APEXII diffractometer (11b) at 123(2) K using Mo-Kα
3
Ph), 7.31–7.19 (m, 6 H, Ph), 7.02–6.84 (m, 8 H, Ph), 6.76 (d, JHH
=
radiation (λ = 0.71073 Å). Direct Methods (7a, 7b, 8a, 8b, 10a, 11a,
3
3
7.9 Hz, 2 H, C6H3), 6.56 (t, JHH = 7.7 Hz, 2 H, C6H3), 6.00 (d, JHH
11b) or Patterson Methods (9b) (SHELXS-97[15]) were used for struc-
= 7.9 Hz, 2 H, C6H3), 3.94 (m, 2 H, CH2), 3.25 (m, 2 H, CH2). 31P{1H} ture solution. Refinement was carried out using SHELXL-97 (full-ma-
NMR ([D6]acetone): δ = 39.2 (s, JPtP = 4192 Hz). (+)-ESI-MS: m/e trix least-squares on F2), and hydrogen atoms were refined using a
1
= 1024.08 [M + H+]. C38H30O6P2PtW (1023.51): calcd. C 44.59, H
2.95, found C 44.55, H 2.95.
riding model (H(O) free). Semi-empirical absorption corrections were
applied. One CHCl3 molecule in 10a is disordered, and some phenyl
groups show high displacement parameters, indicating a possible disor-
der which could not be resolved due to the bad data quality. Four
highly disordered solvent molecules (CH2Cl2) in the crystal structure
of 10b were removed using the SQUEEZE routine in the program
PLATON.[12] Additionally, one phenyl group is disordered, and one
further CH2Cl2 shows high displacement parameters which is also in-
dicative of a disorder which could not be resolved. Details of the crys-
tal structure determinations are listed in Table 3 and Table 4. Crystallo-
graphic data (excluding structure factors) have been deposited with the
Cambridge Crystallographic Data Centre as supplementary publication
no. CCDC-947567 (7a), CCDC-947568 (7b), CCDC-947569 (8a),
CCDC-947570 (8b), CCDC-947571 (9b), CCDC-947572 (10a),
CCDC-947573 (10b), CCDC-947574 (11a), CCDC-947575 (11b).
Copies of the data can be obtained free of charge on application to:
The Director, CCDC, 12 Union Road, GB-Cambridge CB2 1EZ (Fax:
int. +1223/336033; E-mail: deposit@ccdc.cam-ak.uk.
Complex 10a: [VO(acac)2] (67 mg, 0.25 mmol) was added to a solu-
tion of 7a (181 mg, 0.25 mmol) in CH2Cl2 (18 mL). The mixture was
stirred for 3 h and then evaporated to dryness. The dark red residue
was recrystallized from CH2Cl2/Et2O (1:1). Yield 162 mg (0.21 mmol,
82%), m.p. Ͼ 250 °C (dec.). Single crystals suitable for a XRD study
1
were grown by recrystallization from CHCl3. H NMR ([D6]DMSO):
no consistent 1H NMR spectroscopic data could be obtained due to the
paramagnetic nature of the sample. 31P{1H} NMR ([D6]DMSO): δ =
77.0 (br). – (+)-ESI-MS: m/e = 786.01 [M + H+], 807.99 [M + Na+].
ESR (X-band, RT) g = 1.984, a(51V) = 93.5 G. C38H30O5P2PdV·½
CH2Cl2 (828.40): calcd. C 55.82, H 3.77, found C 55.70, H 3.89.
Complex 10b: The dark green complex was prepared from 7b
(122 mg, 150 μmol) and [VO(acac)2] (40 mg, 150 μmol) using the
procedure described for 10a. Yield 105 mg (120 μmol, 80%), m.p.
1
1
Ͼ 250 °C (dec.). H NMR (CD2Cl2): no consistent H NMR spectro-
scopic data could be obtained due to the paramagnetic nature of the
1
Supporting Information (see footnote on the first page of this article):
Tables of selected bond lengths and angles for all crystallographically
independent molecules of 10a,b and 11b, plots of the molecular struc-
tures of 7b, 8b, 9b and the additional crystallographically independent
molecules of 10a,b, and 11b, and EPR spectra of 10a,b.
sample. 31P{1H} NMR (CD2Cl2): δ = 31.0 (s, JPtP = 3918 Hz). (+)-
ESI-MS: m/e = 875.07 [M + H+], 897.05 [M + Na+]. ESR (X-band,
RT) g = 1.980, a(51V) = 93.5 G. C38H30O5P2PtV·CH2Cl2 (959.54):
calcd. C 48.82, H 3.36, found C 49.16, H 3.24.
Complex 11a: [{Ti(μ-O)(acac)2}2] (43 mg, 83 μmol) was added to a
suspension of 7a (120 mg, 166 μmol) in MeOH (15 mL). The mixture
was stirred for 1 h until all solid materials had dissolved to give a dark
red solution. The mixture was stirred for 2 h at 50 °C, allowed to cool
Acknowledgments
to ambient temperature, and concentrated under vacuum to one third We thank the Deutsche Forschungsgemeinschaft (DFG, grant Gu 415/
of the initial volume. The solution was stored at 4 °C until a dark
red, crystalline precipitate had formed and the liquid phase had almost
become colorless. The supernatant solution was removed by decan-
12–1), COST (action CM0802) and Deutscher Akademischer Aus-
tauschdienst (DAAD) for financial support, and the Academy of
Finland for a Research Fellowship. We further thank K. Wohlbold and
tation, and the solid residue collected and dried under slightly reduced J. Trinkner for measurement of mass spectra and Dr· W. Frey (all from
pressure. Yield 95 mg (110 μmol, 66%), m.p. 195 °C. 1H NMR
Institute of Organic Chemistry, University of Stuttgart) for the collec-
(CD2Cl2): δ = 8.0 (br., 1 H, OH of MeOH), 7.39–7.28 (br., 4 H, Ph), tion of X-ray data sets. Dr. B. Sarkar is acknowledged for measure-
3
7.20–7.04 (br., 16 H, Ph), 6.58 (d, JHH = 7.8 Hz, 2 H, C6H3), 6.42 (t,
ment of EPR spectra.
332 www.zaac.wiley-vch.de
© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2014, 325–333

Ditopic Catechol Phosphane as Building Block for Heterometallic Complexes
Table 4. X-ray details for 10a,b, 11a,b.
10a
10b
11a
11b
Empirical formula
C38H30O5P2PdV
·4/3CHCl3
945.06
C38H30O5P2PtV
·2CH2Cl2
1044.44
C40H36O6P2PdTi
·MeOH
860.97
C44H44O6P2PdTi
Formula weight /g mol–1
885.03
T /K
123(2)
123(2)
123(2)
123(2)
Crystal size /mm
crystal system
space group
a /Å
b /Å
c /Å
0.50 ϫ 0.08 ϫ 0.04
monoclinic
P21/n (No.14)
18.945(1)
22.082(2)
28.081(3)
0.16 ϫ 0.12 ϫ 0.04
monoclinic
P21/n (No.14)
23.423(2)
18.647(1)
28.122(2)
0.18 ϫ 0.09 ϫ 0.03
monoclinic
P21/n (No.14)
14.598(1)
12.951(1)
19.652(2)
0.24 ϫ 0.06 ϫ 0.03
monoclinic
P21/n (No.14)
17.7428(6)
20.2475(9)
22.5638(9)
α /°
β /°
97.47(1)
98.84(1)
97.28(1)
95.659(3)
γ /°
V /Å3
11647.8(17)
12
1.617
12136.9(15)
12
1.715
3685.4(5)
4
1.552
8066.5(6)
8
1.458
Z
Dc /Mg·m–3
μ /mm–1
1.105
4.071
0.843
0.770
F(000)
5692
6156
1760
3632
2θmax. /°
50
50
55
50
Reflections collected
Unique reflections
Rint
69656
20428
0.129
20683
20683
0.000
36654
8431
0.051
36717
14106
0.089
max./ min. transmission
Data/restraints/parameters
G.o.F. on F2
R1 [I Ͼ 2 σ(I)]
wR2 (F2)
0.9280 / 0.3917
20428/396/1407
1.04
0.096
0.282
0.8621 / 0.4500
20683 / 51 / 1183
0.95
0.078
0.215
0.9703 / 0.8632
8431 / 1 / 475
1.04
0.039
0.083
0.9655 / 0.8463
14106 / 0 / 973
1.11
0.066
0.126
Largest diff. peak/hole /e·Å–3
1.666 / –2.068
4.809 / –2.481
1.087 / –0.402
0.626 / –0.531
[5] S. Chikkali, D. Gudat, F. Lissner, M. Niemeyer, Th. Schleid, M.
Nieger, Chem. Eur. J. 2009, 15, 482–491.
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Received: November 11, 2013
Published Online: January 9, 2014
Z. Anorg. Allg. Chem. 2014, 325–333
© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
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