Synthesis and structure of cobalt(II) complexes with nitrilotris(methylenephosphonic) acid [Co(H2O)3{NH(CH2PO3H)3}] and Na4[Co{N(CH2PO3)3}] ·13H2O

Abstract

Nitrilotris(methylenephosphonato)triaquacobaltum(II) and tetrasodium nitrilotris(methylenephosphonato)cobaltate(II) tridecahydrate were synthesized and studied. The crystals of [Co(H2O)3{NH(CH2PO3H)3}] (I) are monoclinic, space group P21/c, Z = 4, a = 9.2092(2), b = 16.0540(2), c = 9.7445(2) A, β = 115.778(3)°. The coordination polyhedron of cobalt is a distorted octahedron formed by oxygen atoms. The organophosphorus ligand bridges the neighboring cobalt atoms. The crystals of Na4[Co{N(CH2PO3)3}] · 13H2O (II) are triclinic, space group, P\(\overline 1 \), Z = 2, a = 11.2240(8), b = 11.2663(8), c = 12.3296(8) A, α = 108.513(6)°, β = 97.261(6)°, γ = 117.056(7)°. The cobalt atom is coordinated to form a distorted trigonal bipyramid. Complex II is a chelate in which the cobalt atom closes three five-membered N-C-P-O-Co rings sharing the Co-N bond. The Co atom is incorporated in the Co-O-Co-O ring. Upon dissolution in water, this ring is opened and cobalt(II) atom is hydrolyzed.