Coordinationversushydrogen bonds in the structures of different tris(pyridin-2-yl)phosphoric triamide derivatives

Abstract

The crystalline forms of tris(pyridin-2-yl)phosphoric triamide, OP[NH-2Py]3were investigated using single crystal X-ray diffraction, both as a metal complex [Co{(O)P[NH-2Py]2[NH-2PyH]}2]Cl3, compound1, and as the purely organic pseudopolymorphs, the pure/anhydrate OP[NH-2Py]3,2, monohydrate 2OP[NH-2Py]3·H2O,3and solvate 2OP[NH-2Py]3·2DMF·H2O,4, respectively. An improved model of the metal organic framework (MOF) structure of Cu(ii)O6{[Cu(OCHO)3][(CH3)2NH2]}n,5is also reported. Compound1is the first example of a discrete chelate phosphoric triamide (PT) complex with an [N]3P(O)-based backbone which in the PT compound acts as a flexible tridentate ligand. The structures1,3and4crystallize in the monoclinic space groupP21/n, while the anhydrous form2crystallizes in theR3̄ trigonal space group.5which was obtained as a byproduct of the synthesis process of coordination compounds of OP[NH-2Py]3, crystallizes in the monoclinic space groupI2/c. Hydrogen bonding pattern analysis for the different solid state forms of OP[NH-2Py]3(2-4) shows a 2D sheet of the N-HN linked molecules for2, and a 1D chain and a ten-membered ring motif, both formedviathe hydrogen bonds N-HO, N-HN and O-HO, for3and4, respectively. Of note is the unusual absence of the expected hydrogen bond interaction N-HOP of PT compounds and also a lack of any significant π interactions in structure2. The role of the solvent/hydrate and substituent (aminopyridine) in the formation of the expected hydrogen bond interactions in the studied solid state forms is also investigated. For these structures, crystal packing analysis using 3D Hirshfeld surface (HS), 2D fingerprint plot (FP) and enrichment ratio (E) calculations confirm a competition between the pyridinyl nitrogen and phosphoryl oxygen atoms as H-bond acceptors to construct the N-HN or N-HO contacts. Moreover, the significant differences between the anhydrous form of OP[NH-2Py]3,2, and the monohydrate and solvate forms,3and4, can be correlated to the pseudo-infinite (in2)versusfinite values (in3and4) for the upper values ofdeanddion the related full FPs.