Pourayoubi Mehrdad, Nečas Marek, Negari Monireh
Department of Chemistry, Ferdowsi University of Mashhad, Mashhad 91779, Iran.
Acta Crystallogr C. 2012 Feb;68(Pt 2):o51-6. doi: 10.1107/S0108270111052097. Epub 2012 Jan 6.
In the hydrogen-bond patterns of phenyl bis(2-chlorobenzylamido)phosphinate, C(20)H(19)Cl(2)N(2)O(2)P, (I), and N,N'-bis(2-chlorobenzyl)-N''-(2,2,2-trifluoroacetyl)phosphoric triamide, C(16)H(15)Cl(2)F(3)N(3)O(2)P, (II), the O atoms of the related phosphoryl groups act as double H-atom acceptors, so that the P=O···(H-N)(2) hydrogen bond in (I) and the P=O···(H-N(amide))(2) and C=O···H-N(C(O)NHP(O)) hydrogen bonds in (II) are responsible for the aggregation of the molecules in the crystal packing. The presence of a double H-atom acceptor centre is a result of the involvement of a greater number of H-atom donor sites with a smaller number of H-atom acceptor sites in the hydrogen-bonding interactions. This article also reviews structures having a P(O)NH group, with the aim of finding similar three-centre hydrogen bonds in the packing of phosphoramidate compounds. This analysis shows that the factors affecting the preference of the above-mentioned O atom to act as a double H-atom acceptor are: (i) a higher number of H-atom donor sites relative to H-atom acceptor centres in molecules with P(=O)(NH)(3), (N)P(=O)(NH)(2), C(=O)NHP(=O)(NH)(2) and (NH)(2)P(=O)OP(=O)(NH)(2) groups, and (ii) the remarkable H-atom acceptability of this atom relative to the other acceptor centre(s) in molecules containing an OP(=O)(NH)(2) group, with the explanation that the N atom bound to the P atom in almost all of the structures found does not take part in hydrogen bonding as an acceptor. Moreover, the differences in the H-atom acceptability of the phosphoryl O atom relative to the O atom of the alkoxy or phenoxy groups in amidophosphoric acid esters may be illustrated by considering the molecular packing of compounds having (O)(2)P(=O)(NH) and (O)P(=O)(NH)(N)groups, in which the unique N-H unit in the above-mentioned molecules almost always selects the phosphoryl O atom as a partner in forming hydrogen-bond interactions. The P atoms in (I) and (II) are in tetrahedral coordination environments, and the phosphoryl and carbonyl groups in (II) are anti with respect to each other (the P and C groups are separated by one N atom). In the crystal structures of (I) and (II), adjacent molecules are linked via the above-mentioned hydrogen bonds into a linear arrangement parallel to [100] in both cases, in (I) by forming R(2)(2)(8) rings and in (II) through a combination of R(2)(2)(10) and R(2)(1)(6) rings.
在苯基双（2 - 氯苄基氨基）次膦酸酯（C₂₀H₁₉Cl₂N₂O₂P，（I））和N，N'-双（2 - 氯苄基）-N''-（2,2,2 - 三氟乙酰基）磷酸三酰胺（C₁₆H₁₅Cl₂F₃N₃O₂P，（II））的氢键模式中，相关磷酰基的O原子充当双H原子受体，因此（I）中的P = O···（H - N）₂氢键以及（II）中的P = O···（H - N（酰胺））₂和C = O···H - N（C（O）NHP（O））氢键负责晶体堆积中分子的聚集。双H原子受体中心的存在是由于在氢键相互作用中涉及更多数量的H原子供体位点和较少数量的H原子受体位点。本文还综述了具有P（O）NH基团的结构，目的是在氨基磷酸酯化合物的堆积中找到类似的三中心氢键。该分析表明，影响上述O原子充当双H原子受体偏好的因素为：（i）在具有P（= O）（NH）₃、（N）P（= O）（NH）₂、C（= O）NHP（= O）（NH）₂和（NH）₂P（= O）OP（= O）（NH）₂基团的分子中，相对于H原子受体中心，H原子供体位点数量更多；（ii）在含有OP（= O）（NH）₂基团的分子中，该原子相对于其他受体中心具有显著的H原子接受能力，原因是在所发现的几乎所有结构中，与P原子相连的N原子不作为受体参与氢键形成。此外，通过考虑具有（O）₂P（= O）（NH）和（O）P（= O）（NH）（N）基团的化合物的分子堆积，可以说明磷酰基O原子相对于氨基磷酸酯中烷氧基或苯氧基O原子的H原子接受能力差异，其中上述分子中独特的N - H单元在形成氢键相互作用时几乎总是选择磷酰基O原子作为伙伴。（I）和（II）中的P原子处于四面体配位环境，（II）中的磷酰基和羰基彼此呈反式（P和C基团被一个N原子隔开）。在（I）和（II）的晶体结构中，相邻分子通过上述氢键连接成平行于[100]的线性排列，在（I）中形成R₂²⁸环，在（II）中通过R₂²¹⁰和R₂¹⁶环的组合。
