[1,2-Bis(diphenylphosphanyl)ethane-κ2 P,P]chlorido(isonicotinamide-κN)palladium(II) nitrate acetonitrile monosolvate

The crystal structure of the title complex, [PdCl(dppe)(INAM)]NO3 .CH3CN consists of a PdII metal center in a distorted square-planar environment with hydrogen-bond interactions contributing to the crystal packing. An acetonitrile molecule completes the asymmetric unit.

The Pd II central atom in the title complex, [PdCl(C 26 H 24 P 2 )(C 6 H 6 N 2 O)]NO 3 Á-CH 3 CN or [PdCl(dppe)(INAM)]NO 3 ÁCH 3 CN, where dppe is 1,2-bis(diphenylphosphanyl)ethane and INAM is isonicotinamide, exists in a slightly distorted square-planar environment defined by the two P atoms of the dppe ligand, a chloride ligand and the N atom of the isonicotinamide pyridyl ring. The crystal packing in the structure is held together by hydrogen bonds between the amide of the INAM ligand and the nitrate ions that complete the outer coordination sphere. A molecule of acetonitrile is also found in the asymmetric unit of the title complex.

Structure description
Palladium complexes containing 1,2-bis(diphenylphosphanyl)ethane as a ligand have received much attention over the last decade because of their application in catalysis (Naghipour et al., 2021;Thapa et al., 2019). Recently, some of the focus has shifted to exploring their cytotoxicity (Cullinane et al., 2018;Kuijpers & Blom, 2021) and biological activity (Al-Janabi et al., 2021). In our research group, we have been exploring the synthesis of palladium(II) and copper(II) complexes containing various ancillary ligands and isonicotinamide as active ligand; isonicotinamide has proven to be an effective antimetabolite due to its ability to enhance Sirt1 deacetylase activity, which reduces tumor growth (Li et al., 2009). With that in mind, herein, we report the synthesis and structure of the title palladium(II) dppe complex.
The asymmetric unit of the title compound, depicted in Fig. 1, consists of a Pd II ion in a distorted square-planar coordination environment defined by the two phosphorus atoms data reports of the chelating dppe ligand, an N-bonded INAM molecule, and a chloride ion. An acetonitrile molecule and a nitrate ion complete the asymmetric unit. Selected bond lengths and angles involving the Pd II atom are presented in Table 1. The Pd-Cl bond length in the title complex is in good agreement with the reported values of similar palladium(II) dppe complexes currently available in in the CSD (version 5.42 with update September 2021; Koide et al., 1996;refcode TEPXIV;Owen et al., 2002;refcode HUHZOZ;Owen et al., 2003;refcode UMEDOF). Similarly, the Pd-N distance is also consistent with other structures found in the CSD, where a [Pd(dppe)] 2+ unit is also bonded to the N-atom of a pyridyl ring (Guha et al., 2012;refcode TIFYEO;Uehara et al., 2013;refcode WINQOB;Mane et al., 2021;refcode UTECEE). Nothing unusual is observed in the bond lengths and angles involving the dppe ligand.
Several hydrogen-bonding motifs are present in the crystal structure, with numerical values collated in Table 2. In the crystal packing, molecules self-assemble into sheets aligned along the a axis (Fig. 2) and are held together by N-HÁ Á ÁO interactions between adjacent isonicotinamide ligands. The nitrate ions fill the void between the Pd II complex ions interacting with the isonicotinamide ligands in different units through additional N-HÁ Á ÁO and C-HÁ Á ÁO interactions (Fig. 3).

Synthesis and crystallization
To synthesize the title compound, [1,2-bis(diphenylphosphanyl)ethane]dichloridopalladium(II) (0.100 g, 0.174 mmol) was suspended in 40 ml of acetonitrile and stirred for 15 min. Solid AgNO 3 (0.030 g, 0.18 mmol) was added to the suspension and heated with stirring at 303 K for 2 h. After removing AgCl by filtration, using a 0.45 mm PTFE syringe filter, the resulting pale yellow solution was used to grow crystals by vapor diffusion with diethyl ether at 278 K.

Figure 2
Perspective view of the packing structure of the title salt along the crystallographic a-axis; H atoms are omitted for clarity.

Figure 3
Capped sticks representation of the title compound showing the hydrogen-bond interactions (pink).

Figure 1
The structures of the molecular entities of the title compound with displacement ellipsoids drawn at the 50% probability level; H atoms are omitted for clarity.    Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.