Two polymorphs of bis­(2-carbamoylguanidinium) fluoro­phospho­nate dihydrate

Two polymorphs of bis­(2-carbamoylguanidinium) fluoro­phos­phon­ate dihydrate, 2C₂H₇N₄O⁺·FO₃P^2-·2H₂O, are pre­sented. Polymorph (I), crystallizing in the space group Pnma, is slightly less densely packed than polymorph (II), which crystallizes in Pbca. In (I), the fluoro­phosphon­ate anion is situated on a crystallographic mirror plane and the O atom of the water mol­ecule is disordered over two positions, in contrast with its H atoms. The hydrogen-bond patterns in both poly­morphs share similar features. There are O-H...O and N-H...O hydrogen bonds in both structures. The water mol­ecules donate their H atoms to the O atoms of the fluoro­phosphon­ates exclusively. The water mol­ecules and the fluoro­phosphon­ates participate in the formation of R⁴₄(10) graph-set motifs. These motifs extend along the a axis in each structure. The water mol­ecules are also acceptors of either one [in (I) and (II)] or two [in (II)] N-H...O hydrogen bonds. The water mol­ecules are significant building elements in the formation of a three-dimensional hydrogen-bond network in both structures. Despite these similarities, there are substantial differences between the hydrogen-bond networks of (I) and (II). The N-H...O and O-H...O hydrogen bonds in (I) are stronger and weaker, respectively, than those in (II). Moreover, in (I), the shortest N-H...O hydrogen bonds are shorter than the shortest O-H...O hydrogen bonds, which is an unusual feature. The properties of the hydrogen-bond network in (II) can be related to an unusually long P-O bond length for an unhydrogenated fluoro­phosphon­ate anion that is present in this structure. In both structures, the N-H...F inter­actions are far weaker than the N-H...O hydrogen bonds. It follows from the structure analysis that (II) seems to be thermodynamically more stable than (I).

Mixed crystals of 2-carbamoylguanidinium with hydrogen fluoro­phos­phonate and hydrogen phosphite in the ratios 1:0, 0.76 (2):0.24 (2) and 0.115 (7):0.885 (7)

The title compounds, 2-carbamoylguanidinium hydrogen fluoro­phospho­nate, C₂H₇N₄O⁺·HFO₃P^-, (I), 2-carbamoyl­guan­i­dinium-hydrogen fluoro­phospho­nate-hydrogen phosphite (1/0.76/0.24), C₂H₇N₄O⁺·0.76HFO₃P^-·0.24H₂O₃P^-, (II), and 2-carbamoylguanidinium-hydrogen fluoro­phospho­nate-hydrogen phosphite (1/0.115/0.885), C₂H₇N₄O⁺·0.115HFO₃P^-·0.885H₂O₃P^-, (III), are isostructural with guanylurea hy­drogen phosphite, C₂H₇N₄O⁺·H₂O₃P^- [Fridrichová, Nemec, Císarová & Nemec (2010). CrystEngComm, 12, 2054-2056]. They constitute structures where the hydrogen phosphite anion has been fully or partially replaced by hydrogen fluoro­phospho­nate. The title structures are the fourth example of isostructural compounds which differ by the presence of hydrogen fluoro­phospho­nate and hydrogen phosphite or fluoro­phospho­nate and phosphite anions. Moreover, the present study reports structures with these mixed anions for the first time. In the reported mixed salts, the P and O atoms of either anion overlap almost exactly, as can be judged by comparison of their equivalent isotropic displacement parameters, while the P-F and P-H directions are almost parallel. There are strong O-H...O hydrogen bonds between the anions, as well as strong N-H...O hydrogen bonds between the 2-carbamoylguanidinium cations in the title structures. Altogether they form a three-dimensional hydrogen-bond pattern. Inter­estingly, rare N-H...F inter­actions are also present in the title structures. Another exceptional feature concerns the P-O(H) distances, which are about as long as the P-F distance. The dependence of P-F distances on the longest P-O distances in FO₃P^2- or HFO₃P^- is presented. The greater content of hydrogen phosphite in the mixed crystals causes a larger deformation of the cations from planarity.

Two new XP(O)[NHC(CH₃)₃]₂ phosphor­amidates, with X = (CH₃)₂N and [(CH₃)₃CNH]₂P(O)(O)

In N,N′-di-tert-butyl-N′′,N′′-dimethyl­phosphoric triamide, C₁₀H₂₆N₃OP, (I), and N,N′,N′′,N′′′-tetra-tert-but­oxy­bis(phos­phonic diamide), C₁₆H₄₀N₄O₃P₂, (II), the extended structures are mediated by P(O)...(H—N)₂ inter­actions. The asymmetric unit of (I) consists of six independent mol­ecules which aggregate through P(O)...(H—N)₂ hydrogen bonds, giving R₂¹(6) loops and forming two independent chains parallel to the a axis. Of the 12 independent tert-butyl groups, five are disordered over two different positions with occupancies ranging from to . In the structure of (II), the asymmetric unit contains one mol­ecule. P(O)...(H—N)₂ hydrogen bonds give S(6) and R₂²(8) rings, and the mol­ecules form extended chains parallel to the c axis. The structures of (I) and (II), along with similar structures having (N)P(O)(NH)₂ and (NH)₂P(O)(O)P(O)(NH)₂ skeletons extracted from the Cambridge Structural Database, are used to compare hydrogen-bond patterns in these families of phospho­ramidates. The strengths of P(O)[...H—N]_x (x = 1, 2 or 3) hydrogen bonds are also analysed, using these compounds and previously reported structures with (N)₂P(O)(NH) and P(O)(NH)₃ fragments.

A new platinum–bromine cyclo­hexane­diamine complex from the family of cancer cytostatics

Another new substance from the family of Pt-based coord­ination complexes with potential use in cancer chemotherapy has been synthesized, crystallized and structurally characterized. In this compound {systematic name cis-dibromido[(1R,2R)-cyclo­hexane-1,2-diamine-κ²N,N′]platinum(II)}, cis-[PtBr₂(C₆H₁₄N₂)], there are two mol­ecules with very similar conformations in the asymmetric unit. The component species inter­act by way of N—H...Br and C—H...Br hydrogen bonds to give two-dimensional networks which lie parallel to the (100) plane.