catena-Poly[[(1,10-phenanthroline-κ2 N,N′)lead(II)]-di-μ-nitrato-κ3 O,O′:O′′;κ3 O:O′,O′′-[(1,10-phenanthroline-κ2 N,N′)lead(II)]-bis(μ-2,2,2-trichloroacetato-κ2 O:O′)]

In the title PbII complex, [Pb2(C2Cl3O2)2(NO3)2(C12H8N2)2]n, the 1,10-phenanthroline ligand is chelating, the nitrate anion chelates one PbII ion and simultaneously bridges a neighbouring PbII ion via the third O atom, and the trichloroacetate anion is bidentate, bridging two PbII ions. The coordination geometry is based on a pentagonal–bipramidal geometry defined by an N2O5 donor set with no obvious stereochemical role for the lead-bound lone pair of electrons. The coordination polymer has a zigzag topology along [010] and comprises alternating eight-membered {PbONO}2 and {PbOCO}2 rings.

In the title Pb II complex, [Pb 2 (C 2 Cl 3 O 2 ) 2 (NO 3 ) 2 (C 12 H 8 N 2 ) 2 ] n , the 1,10-phenanthroline ligand is chelating, the nitrate anion chelates one Pb II ion and simultaneously bridges a neighbouring Pb II ion via the third O atom, and the trichloroacetate anion is bidentate, bridging two Pb II ions. The coordination geometry is based on a pentagonal-bipramidal geometry defined by an N 2 O 5 donor set with no obvious stereochemical role for the lead-bound lone pair of electrons. The coordination polymer has a zigzag topology along [010] and comprises alternating eight-membered {PbONO} 2 and {PbOCO} 2 rings.

Related literature
On the stereochemical activity of lone pairs of electrons in Pb II structures, see: Davidovich et al. (2009). For recent structural studies of mixed-ligand Pb II compounds, see: Shahverdizadeh et al. (2008Shahverdizadeh et al. ( , 2011a. For specialized crystallization techniques, see: Harrowfield et al. (1996).
A view of the asymmetic unit is shown in Fig. 1. This comprises a Pb II atom, a chelating 1,10-phenanthroline molecule, a nitrate anion and a trichloroacetate anion. The nitrate anion chelates one Pb II atom and at the same time bridges a second Pb II atom via the third O atom. The trichloroacetate anion is bidentate, bridging two Pb II atoms. Both bridges are non-symmetric, Table 1. The resulting coordination geometry, Fig. 2, is based on a distorted pentagonal bipyramid with no obvious role for the lead-bound lone pair of electrons.
The resulting polymeric chain along [010] has a zigzag topology with the backbone being defined by alternating eightmembered {PbONO} 2 and {PbOCO} 2 rings, Fig. 3. Experimental 1,10-Phenanthroline (1 mmol) was placed in one arm of a branched tube (Harrowfield et al., 1996) and a mixture of lead(II) nitrate (1 mmol) and trichloroacetic acid (1 mmol) in the other. Methanol was then added to fill both arms, the tube sealed and the ligand-containing arm immersed in a bath at 333 K, while the other was left at ambient temperature.
After two weeks, crystals had deposited in the arm held at ambient temperature. They were filtered off, washed with acetone and ether, and air-dried. Yield: 65%. M.pt. = 491 K.

Refinement
Carbon-bound H-atoms were placed in calculated positions [C-H 0.95 Å, U iso (H) 1.2U eq (C)] and were included in the refinement in the riding model approximation.