rac-Dichlorido(1-{(diphenyl­phosphan­yl)[2-(diphenyl­phosphan­yl)phen­yl]meth­yl}ferrocene-κ2 P,P′)palladium(II) dimethyl sulfoxide disolvate

Raffael Schuecker; Walter Weissensteiner; Kurt Mereiter

doi:10.1107/S160053681103618X

. 2011 Sep 14;67(Pt 10):m1377–m1378. doi: 10.1107/S160053681103618X

rac-Dichlorido(1-{(diphenylphosphanyl)[2-(diphenylphosphanyl)phenyl]methyl}ferrocene-κ² P,P′)palladium(II) dimethyl sulfoxide disolvate

Raffael Schuecker ^a, Walter Weissensteiner ^a, Kurt Mereiter ^b,^*

PMCID: PMC3201499 PMID: 22064964

Abstract

The racemic title compound, [FePdCl₂(C₅H₅)(C₃₆H₂₉P₂)]·2(CH₃)₂SO, features a Pd-chelating 1,3-diphosphine, which is substituted at a P-bearing asymmetric C atom by a ferrocenyl group. The Pd^II atom is in a distorted quadratic coordination by two P and two Cl atoms with bond lengths of 2.2414 (3) and 2.2438 (3) Å for Pd—P, and 2.3452 (3) and 2.3565 (3) Å for Pd—Cl. The conformation of the Pd complex is controlled by an intramolecular slipped π–π stacking interaction between a phenyl and a cyclopentadienyl ring with corresponding C⋯C distances starting at 3.300 (2) Å and the distance between ring centroids being 3.674 (2) Å. The crystal structure is stabilized by C—H⋯Cl and C—H⋯O hydrogen bonds. The (CH₃)₂SO solvent molecules are arranged in layers parallel to (101) and are linked in pairs by C—H⋯O interactions. One (CH₃)₂SO molecule is orientationally disordered [occupancy ratio 0.8766 (17):0.1234 (17)] with sulfur in two positions at both sides of its C₂O triangle.

Related literature

For general information on ferrocene-based diphosphines and their applications in asymmetric catalysis, see: Togni (1996 ▶); Blaser et al. (2007 ▶); Dai & Hou (2010 ▶). For the synthesis, coordination behavior, and use in asymmetric catalysis of ligands based on [diphenylphosphanyl-(2-diphenylphosphanylphenyl)methyl]-ferrocene, see: Schuecker et al. (2010 ▶); Lotz et al. (2010 ▶).

Experimental

Crystal data

[FePdCl₂(C₅H₅)(C₃₆H₂₉P₂)]·2C₂H₆OS
M _r = 978.03
Triclinic,
a = 10.9878 (8) Å
b = 11.5275 (8) Å
c = 17.1405 (12) Å
α = 78.720 (2)°
β = 81.796 (2)°
γ = 78.143 (2)°
V = 2071.8 (3) Å³
Z = 2
Mo Kα radiation
μ = 1.13 mm⁻¹
T = 100 K
0.59 × 0.45 × 0.36 mm

Data collection

Bruker SMART APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2003 ▶) T _min = 0.58, T _max = 0.67
37987 measured reflections
11991 independent reflections
11375 reflections with I > 2σ(I)
R _int = 0.018

Refinement

R[F ² > 2σ(F ²)] = 0.021
wR(F ²) = 0.055
S = 1.02
11991 reflections
502 parameters
H-atom parameters constrained
Δρ_max = 0.59 e Å⁻³
Δρ_min = −0.60 e Å⁻³

Data collection: SMART (Bruker, 2003 ▶); cell refinement: SAINT (Bruker, 2003 ▶); data reduction: SAINT and XPREP (Bruker, 2003 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: PLATON (Spek, 2009 ▶) and publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S160053681103618X/gk2404sup1.cif

e-67-m1377-sup1.cif^{(44.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S160053681103618X/gk2404Isup2.hkl

e-67-m1377-Isup2.hkl^{(586.2KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C6—H6⋯O1ⁱ	1.00	2.40	3.3365 (17)	156
C15—H15⋯Cl1ⁱⁱ	0.95	2.70	3.4262 (12)	133
C19—H19⋯Cl1	0.95	2.66	3.2410 (12)	120
C23—H23⋯O1ⁱ	0.95	2.47	3.3239 (16)	149
C25—H25⋯Cl1	0.95	2.70	3.5075 (13)	143
C29—H29⋯O1ⁱ	0.95	2.45	3.3201 (16)	152
C31—H31⋯Cl2	0.95	2.76	3.3893 (13)	125
C42—H42A⋯O2	0.98	2.42	3.368 (2)	163
C45—H45A⋯Cl1ⁱⁱⁱ	0.98	2.83	3.6881 (16)	147

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

This work was kindly supported by SOLVIAS AG.

supplementary crystallographic information

Comment

Chiral ferrocenyldiphosphines are widely used as ligands for enantioselective PGM catalysts (PGM = platinum group metals) because they give excellent results in asymmetric hydrogenations and other transformations (Togni, 1996; Blaser et al., 2007; Dai & Hou, 2010). Most of these ferrocenyldiphosphines are based on a planar chiral 1,2-disubstituted ferrocene backbone. Recently, it was found that chiral diphosphines lacking this planar-chiral backbone but employing ferrocene merely as a bulky substituent of an asymmetric sp³-carbon atom within a ferrocene-free 1,3-diphosphine system are also showing promising enantioselectivities for their PGM catalyst complexes (Schuecker et al., 2010; Lotz et al., 2010). Within the frame of a corresponding project the racemic title compound, (I), was synthesized and studied by X-ray diffraction before turning to the synthesis of the enantiopure equivalent recently reported by Lotz et al. (2010).

(I) is a dimethylsulfoxide (DMSO) solvate of the PdCl₂ complex of racemic 2-[diphenylphosphanyl-(2-diphenylphosphanyl-phenyl)-methyl]-ferrocene and crystallizes in the centrosymmetric space group P1 with a cell content of two formula units. The asymmetric unit including the two DMSO molecules is shown in Fig. 1. Palladium has a distorted square planar coordination by two Cl atoms in terminal positions and by the two P atoms of the chelating 1,3-diphosphine ligand. The r.m.s. deviation from planarity of the PdCl₂P₂ fragment is 0.191 Å. Bond lengths in the Pd-complex of (I) show normal values and agree very well with those found in the crystal structure of its enantiopure chiral equivalent (Lotz et al., 2010), which crystallizes as a chloroform trisolvate in the non-centrosymmetric space group P2₁ and will be subsequently desgnated as (II). Disregarding a librating cyclopentadienyl ring in (II), the bond lengths in the Pd-complexes of (I) and (II) agree on the average within 0.006 Å with a maximum difference of 0.024 Å. With respect to bond angles and torsion angles the Pd-complexes in (I) and (II) show larger differences. Excluding ring bond angles the mean difference in bond angles is 2.3° with maximum differences of 7.6° for C24—P1—Pd1 and 5.6° for C18—P1—Pd1. The differences in torsion angles between (I) and (II) are even larger and lead to significantly differing conformations of both Pd-complexes, as demonstrated by Fig. 2. As result there is in (I) a distinct intramolecular π-π-stacking interaction between the phenyl ring C30—C35 and the monosubstituted cyclopentadienyl ring C1—C5 of the ferrocenyl moiety, which is entirely absent in the solid state structure of (II). Moreover are the phenyl rings of both complexes showing notably different orientations (Fig. 2). The intramolecular π-π-stacking interaction in (I) is characterized by C···C distances starting with 3.300 (2) Å (C3···C31) and a distance between ring centroids of 3.674 (2) Å (Fig. 1). The dihedral angle between the rings C1—C5 and C30—C35 is 10.85 (7)°. The torsion angles P1—C11—C1—C5 and C13—P2—C30—C35 are 160.05 (9)° and -38.11 (11)° in (I), and 104.8 (3)° and -71.1 (3)° in (II) (Lotz et al., 2010), respectively.

A packing diagram of the structure of (I) is depicted in Fig. 3. The structure is stabilized by three intramolecular and two intermolecular C—H···Cl and four intermolecular C—H···O interactions listed in Table 1. The DMSO solvent molecules are arranged in layers parallel to (101). Their mutual interaction is limited to one C42—H···O2 bond.

Experimental

A solution of racemic [diphenylphosphanyl-(2-diphenylphosphanylphenyl)methyl]-ferrocene (65 mg, 100 µmol; for synthesis, see: Lotz et al., 2010) in benzene (2 ml) was added to a suspension of dichlorobis(acetonitrile) palladium(II) (26 mg, 100 µmol) in benzene (1 ml) and the resulting mixture was stirred at r.t. for 16 h. After filtration, the beige precipitate was washed with benzene and diethyl ether and was dried in vacuo. Crystals suitable for X-ray diffraction were obtained from a warm saturated solution of the complex in dimethylsulfoxide upon cooling to room temperature.