Chlorido{2-[(dimethylamino)methyl]benzeneselenolato-κ2 N,Se}(triphenylphosphane-κP)palladium(II)

The asymmetric unit of the title compound, [PdCl(C9H12NSe)(C18H15P)], contains two independent molecules. In both cases, the Pd2+ cations are coordinated by the Se and N atoms of the chelating bidentate 2-[(dimethylamino)methyl]benzeneselenolate ligand. The chloride ligand lies trans to selenium and the triphenylphosphane ligand is trans to nitrogen. The Pd—Se bond lengths in the two independent coordination environments of Pd are 2.3801 (4) and 2.3852 (4) Å, the Pd—P bond lengths are 2.2562 (8) and 2.2471 (8) Å, the Pd—N bond lengths are 2.172 (2) and 2.158 (2) Å, and the Pd—Cl bond lengths are 2.3816 (8) and 2.3801 (8) Å. The square-planar coordination around one Pd2+ cation is less distorted than that around the other.


Related literature
Financial support from the Jenni and Antti Wihuri Foundation (EMT) and the Academy of Finland is gratefully acknowledged.

Comment
The ligand exchange reactions of [MCl 2 (PPh 3 ) 2 ] (M = Pd, Pt) by organoselenolates afford mononuclear metal complexes in the case of platinum, (see for instance, Hannu et al., 2000, Hannu-Kuure et al., 2003a, but in case of palladium dinuclear or complexes of even higher nuclearity are generally obtained, as exemplified by Hannu-Kuure et al. (2003b, 2004 and Wagner et al. (2005). Mononuclear palladium complexes can be obtained by using chelating phosphines such as 1,2-bis(diphenylphosphino)ethane (Risto et al., 2007). Organoselenolates containing additional donor atoms can also form stable monomeric palladium complexes. We are interested in the use of the monomeric palladium chalcogenolato complexes as building blocks for the systematic construction of polynuclear metal complexes.
[PdX(C 9 H 12 NSe)(C 18 H 15 P)] (X = Br, I) has recently been prepared by the oxidative addition of [2-(N,N- [2-(N,N-dimethylamino)methyl]benzeneselenolate. The 77 Se NMR spectrum showed, in addition to the chemical shift of the title compound at 258 p.p.m., also a resonance at 422 p.p.m.. It is possible that the selenolate has been oxidized during the reaction and formed a diselenide, the chemical shift of which has also been reported by Chakraborty et al. (2011).
The sum of the bond angles around Pd1 is 360.12° and around Pd2 360.76°. However, the computation of the leastsquares planes of the square-planar coordination environments involving Pd1 and Pd2 indicates that in both cases the atoms deviate from planarity. The distortion is more prominent for Pd2 than for Pd1.
The bond lengths and angles around the Pd atoms are shown in Table 1. The Pd1-Se1 bond length is 2.3801 (4) Å and

Experimental
Freshly prepared diethyl ether solution of lithium [2-(N,N-dimethylamino)methyl]benzeneselenolate (2 ml; 0.089 mmol/ml) was added to [PdCl 2 (PPh 3 ) 2 ] (0.051 g, 0.073 mmol) in 4 ml of THF in an 10 mm NMR tube under an argon atmosphere. The solution immediately turned red and the 31 P and 77 Se NMR spectra were recorded. Slow evaporation of the solution gave a small crop of red crystals of [PdCl(C 9 H 12 NSe)(C 18 H 15 P)]. NMR data of the title compound: 77 Se NMR 258 p.p.m., 31 P NMR 32.2 p.p.m..

Refinement
H atoms were positioned geometrically and refined using a riding model with C-H = 0.95 Å and with U iso (H) = 1.2 U eq (C) and 0.98 Å and U iso (H) = 1.2 U eq (C) for the aryl and methyl H atoms, respectively.

Figure 1
The molecular structure of the title compound indicating the numbering of the atoms. The thermal ellipsoids have been drawn at 50% probability. The hydrogen atoms have been omitted for clarity.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.