Dipotassium tetrakis(thiocyanato-κS)palladate(II)–(2,2′-bipyrimidine-κ2 N 1,N 1′)bis(thiocyanato-κS)palladium(II) (1/2)

The asymmetric unit of the title compound, K2[Pd(NCS)4]·2[Pd(NCS)2(C8H6N4)], contains two crystallographically independent half-molecules of the anionic PdII complex, two K+ cations and two independent neutral PdII complexes; an inversion centre is located at the centroid of each anionic complex. In the anionic complexes, each PdII ion is four-coordinated in an almost regular square-planar environment by four S atoms from four SCN− anions, and the PdS4 unit is exactly planar. In the neutral complexes, the PdII ion has a slightly distorted square-planar coordination environment defined by two pyrimidine N atoms derived from a chelating 2,2′-bipyrimidine ligand and two mutually cis S atoms from two SCN− anions. Both 2,2′-bipyrimidine ligands are almost planar [dihedral angle between the rings = 3.98 (16) and 4.57 (17)°] and also chelate to a potassium ion from their other two N atoms. In the crystal, the K+ ions interact with various S and N atoms of the ligands, forming a three-dimensional polymeric network, in which the shortest K⋯K contacts between the KN7S polyhedra are 4.4389 (17) and 4.4966 (18) Å. Intra- and intermolecular C—H⋯S and C—H⋯N hydrogen bonds are also observed.

The asymmetric unit of the title compound, K 2 [Pd(NCS) 4 ]Á-2[Pd(NCS) 2 (C 8 H 6 N 4 )], contains two crystallographically independent half-molecules of the anionic Pd II complex, two K + cations and two independent neutral Pd II complexes; an inversion centre is located at the centroid of each anionic complex. In the anionic complexes, each Pd II ion is fourcoordinated in an almost regular square-planar environment by four S atoms from four SCN À anions, and the PdS 4 unit is exactly planar. In the neutral complexes, the Pd II ion has a slightly distorted square-planar coordination environment defined by two pyrimidine N atoms derived from a chelating 2,2 0 -bipyrimidine ligand and two mutually cis S atoms from two SCN À anions. Both 2,2 0 -bipyrimidine ligands are almost planar [dihedral angle between the rings = 3.98 (16) and 4.57 (17) ] and also chelate to a potassium ion from their other two N atoms. In the crystal, the K + ions interact with various S and N atoms of the ligands, forming a three-dimensional polymeric network, in which the shortest KÁ Á ÁK contacts between the KN 7 S polyhedra are 4.4389 (17) and 4.4966 (18) Å . Intra-and intermolecular C-HÁ Á ÁS and C-HÁ Á ÁN hydrogen bonds are also observed.

Related literature
For the crystal structure of K 2 [Pd (SCN)   In the two neutral complexes, each Pd II ion has a slightly distorted square-planar coordination environment defined by two pyrimidine N atoms derived from a chelating bpym ligand and two mutually cis S atoms from two SCNanions. The complexes are fairly different in geometry, because the coordination modes of the anions are significantly different. The two thiocyanato ligands are located on the same side of the PdS 2 N 2 unit plane in the complex with Pd1, whereas in the other complex with Pd2, the ligands lie on the opposite sides of the PdS 2 N 2 unit. But, the Pd-N and Pd-S bond lengths are nearly equivalent, respectively [Pd-N = 2.059 (3)-2.074 (3) Å; Pd-S = 2.2829 (11)-2.3077 (11) Å] ( Table 1). The bpym ligands are slightly inclined to the least-squares plane of the PdS 2 N 2 unit [maximum deviation = 0.090 (1) Å], making dihedral angles of 9.55 (9)° in the complex with Pd1 and 7.28 (7)° in the complex with Pd2.
In the crystal structure, the K + ions interact with the various S and N atoms of the ligands with the distances of K···S =

Refinement
H atoms were positioned geometrically and allowed to ride on their respective parent atoms: C-H = 0.95 Å with U iso (H) = 1.2U eq (C). The highest peak (0.65 e Å -3 ) and the deepest hole (-0.59 e Å -3 ) in the difference Fourier map are located 0.71 Å and 0.83 Å, respectively, from the Pd1 atom.

Figure 1
A structure detail of the title compound, with displacement ellipsoids drawn at the 30% probability level for non-H atoms. Unlabelled atoms are generated by the application of the inversion centres.

Dipotassium tetrakis(thiocyanato-κS)palladate(II)-(2,2′-bipyrimidine-κ 2 N 1 ,N 1′ )bis(thiocyanato-κS)palladium(II)
(1/2) 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.