Synthesis, structure, and properties of nickel complexes with nitrilotris(methylenephosphonic acid) [Ni(H₂O)3N(CH2PO₃H)₃] and Na₄[Ni(H₂O)N(CH₂PO₃)₃] ∙ 11H₂O

Nitrilotris(methylenephosphonato)triaquanickel and tetrasodium nitrilotris(methylenephosphonato) aquanickelate undecahydrate were synthesized and characterized. The crystal of [Ni(H₂O)₃N(CH₂PO₃H)₃] is composed of linear coordination polymers and belongs to sp. gr. P2₁/c, Z = 4, a = 9.17120(10) Å, b = 16.05700(10) Å, c = 9.70890(10) Å, β = 115.830(2)°. The Ni atom is in an octahedral coordination formed by two oxygen atoms of one phosphonate ligand, one oxygen atom of another ligand molecule, and three water molecules in a meridional configuration. The crystal of Na₄[Ni(H₂O)N(CH₂PO₃)₃] ∙ 11H₂O has an island dimeric chelate structure and belongs to sp. gr. C2/c, Z = 8, a = 18.7152(2) Å, b = 12.05510(10) Å, c = 21.1266(2) Å, β = 104.4960(10)°. The Ni atom has a slightly distorted octahedral coordination involving one nitrogen atom and closes three five-membered N–C–P–O–Ni rings sharing the Ni–N bond.