Three new [XC(O)NH]P(O)[N(CH2C6H5)2]2phosphoric triamides (X= CClF2, 3-F-C6H4and 3,5-F2-C6H3): a database analysis of tertiary N-atom geometry in compounds with a C(O)NHP(O)[N]2core

Abstract

In the phosphoric triamides N,N,N',N'-tetrabenzyl-N''-(2-chloro-2,2-difluoroacetyl)phosphoric triamide, C(30)H(29)ClF(2)N(3)O(2)P, (I), N,N,N',N'-tetrabenzyl-N''-(3-fluorobenzoyl)phosphoric triamide, C(35)H(33)FN(3)O(2)P, (II), and N,N,N',N'-tetrabenzyl-N''-(3,5-difluorobenzoyl)phosphoric triamide, C(35)H(32)F(2)N(3)O(2)P, (III), the tertiary N atoms of the dibenzylamido groups have sp(2) character with minimal deviation from planarity. The sums of the three bond angles about the N atoms in (I)-(III) deviate by less than 8° from the planar value of 360°. The geometries of the tertiary N atoms in all phosphoric triamides with C(O)NHP(O)[N](2) skeletons deposited in the Cambridge Structural Database [CSD; Allen (2002). Acta Cryst. B58, 380-388] have been examined and the bond-angle sums at the two tertiary N atoms (SUM1 and SUM2) and the parameter ΔSUM (= SUM1 - SUM2) considered. It was found that in compounds with a considerable ΔSUM value, the more pyramidal N atoms are usually oriented so that the corresponding lone electron pair is anti with respect to the P=O group. In (I), (II) and (III), the phosphoryl and carbonyl groups, separated by an N atom, are anti with respect to each other. In the C(O)NHP(O) fragment of (I)-(III), the P-N bond is longer and the O-P-N angle is contracted compared with the other two P-N bonds and the O-P-N angles in the molecules. These effects are also seen in analogous compounds deposited in the CSD. Compounds with [C(O)NH]P(O)[N]X (X ≠ N), such as compounds with a [C(O)NH]P(O)[N][O] skeleton, have not been considered here. Also, compounds with a [C(O)NH](2)P(O)[N] fragment have not been reported to date. In the crystal structures of all three title compounds, adjacent molecules are linked via pairs of P=O···H-N hydrogen bonds, forming dimers with C(i) symmetry.