Aquachlorido(2-{[6-(dimethylamino)pyrimidin-4-yl]sulfanyl}pyrimidine-4,6-diamine)copper(II) chloride hydrate

The copper(II) complex of the non-symmetric, bidentate ligand 2-{[6-(dimethylamino)pyrimidin-4-yl]sulfanyl}pyrimidine-4,6-diamine exhibits distorted square pyramidal geometry around the metal centre, with disorder in the axial position, occupied by chloride or water. The six-membered metal–chelate ring is in a boat-conformation, and short intermolecular S⋯S interactions are observed.


Chemical context
Non-symmetric ligand-metal complexes have been explored for their applications in chiral synthesis (Asay & Morales-Morales, 2015;Pfaltz & Drury, 2004), or for their potential to yield new multimetallic topologies which combine homo-and heteroleptic sites into a single molecule (Dawe et al., 2006). Non-symmetric thio-bis-(pyridin-2-yl) or bis-(pyrimidin-2-yl) ligands are known, and upon bidentate coordination with transition metal cations, these form six-membered chelate rings, which adopt a boat-shaped conformation (Fig. 1). Some reported transition metal complexes resulting from this class of ligands have been employed as possible alternatives to traditional chemotherapy drugs (Ray et al., 1994;Mandal et al., 2007), as a step en route to new thrombin inhibitors (Chung et al., 2003), and have led to the formation of one Cu I 30-nuclear cluster (Li et al., 2012).
In the interest of exploring simultaneous coordination chemistry and anion-ligand affinity via hydrogen-bonding interactions, the non-symmetric ligand 2-{[6-(dimethylamino)pyrimidin-4-yl]sulfanyl}pyrimidine-4,6-diamine (C 10 H 13 N 7 S; L1), was synthesized, and its metal complex with copper(II) chloride, is reported here. Even upon metal coordination, the ligand can still serve as a hydrogen-bond donor to anions via the amine moieties. Alternatively, these free amines could also act as possible anchors for surface attachment, with a view towards future device applications.
which are significantly longer than the C-N bonds in the square plane (  (Teles et al., 2006). In this complex, the authors report = 0.06, with the square plane formed by the two nitrogen atoms from DPS, a coordinating water molecule, and one chloride ion (with the second chloride occupying the axial position). Similar to the reported structure here, the six-membered chelate ring adopts a boat conformation, which is characteristic for transition metal complexes with this class of ligands upon bidentate coordination (vide infra).

Supramolecular features
In the crystal, molecules of the title complex pack in columns, parallel to the crystallographic b axis (Fig. 3), with short SÁ Á ÁS i intermolecular distances [3.7327 (3) Å ; symmetry code: (i) Àx + 1, y + 1 2 , Àz + 3 2 ]. Note that each chelated 'boat' points in the same direction within a column, and the opposite direction is observed in adjacent columns.

Database survey
A survey was performed of the Cambridge Structural Database (version 5.38 with May 2017 updates; Groom et al., 2016), using ConQuest (version 1.19;Bruno et al., 2002), for sixmembered transition metal chelate rings resulting from bidentate ligand coordination, where the metal was any transition metal, and the other ring components were N-C-S-C-N. Further, within the ligand, each C-N was required to be part of a six-membered ring, where the remaining four atoms could be any non-metal, and the bond type within the ring was unspecified (allowed to be 'any' bond type). This resulted in 74 hits, which were then manually sorted to omit systems where the ligand exhibited anything greater than bidenticity, leaving 68 structures for further analysis using Mercury (version 3.9; Macrae et al., 2006). All of these exhibited boat-shaped puckering of the chelate ring, with mean values for 1 = 43 (7) and 2 = 37 (5) . While the larger angle for the title complex is 2, both 1 and 2 are within two standard deviations of comparable structures from the database.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. Hydrogen atoms were introduced in calculated positions and refined using a riding model, except those bonded to oxygen or nitrogen atoms, which were introduced in difference-map positions. N-H hydrogen atoms were refined isotropically, with no restraints. All O-H hydrogen atoms (all associated with water molecules) were refined with U iso (H) 1.5 times that of the parent atoms and rotating geometry constraints (AFIX 7). Similar distance restraints (SADI, esd 0.02) were applied for all water molecules.
The structure exhibited significant disorder. This included main fragment disorder in the coordination sphere around Cu1. As such, similar distance restraints (SADI, esd 0.02) were applied to the Cu-OH 2 and Cu-Cl bonds; for each, one O atom (O1) and one Cl atom (Cl1) were fully occupied, while the other (O2 and Cl2) were at partial occupancy, occupying the same coordination site on Cu1, with a sum of their occupancy equal to one. Identical anisotropic displacement parameter (EADP) constraints were applied to Cl2 and O2. Finally, EADP constraints were also applied to a disordered water molecule (O4 and O5), with a sum occupancy of one.
While the structure does exhibit significant disorder, careful consideration was given to ensure that: (i) charge balance was established; (ii) the model was consistent with a reasonable hydrogen-bonding network; and (iii) the next highest residual electron density peak was associated along a C-S bond.

Computing details
Data collection: APEX2 (Bruker, 2012); cell refinement: CrysAlis PRO (Rigaku OD, 2015); data reduction: CrysAlis PRO (Rigaku OD, 2015); program(s) used to solve structure: SHELXT (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2016 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009). 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.