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The X-ray crystallographic structures of 18 fluorinated N-phenylmaleimides and corresponding phthalimides of different degree and positions of fluorine substituents, including two compounds each in two polymorphic forms, have been determined in order to study the effect of fluorine substitution on the solid state organization in competition with stronger oxygen and nitrogen H-acceptor sites. The data suggest that C-H • • • O contacts formed in the crystalline packings play the dominant role but C-H • • • F contacts are also of relevance with the fluorine atoms being more specific in making a selection from potential hydrogen contacts. The F • • • F and F • • • π F contacts observed are rather secondary in these structures and mostly determined by the packing. Unexpectedly, a π • • • π F interaction is found only in two exceptional cases for dimer formation contradicting the common opinion of π • • • π F stacking as being a robust supramolecular synthon.

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Melem (1), as one of the most important representatives of the tri-s-triazine compounds, can be used as a nucleophilic reagent in reactions with phthalic acid derivatives. The synthesis of 2,5,8-triphthalimido-tri-s-triazine (C(6)N(7)(phthal)(3), 2) was investigated starting from phthalic anhydride or phthalic dichloride in various solvents, at different temperatures as well as in the solid state. NMR measurements (solution and solid state), IR spectroscopy and elemental analysis indicated the formation of a cyclic imide. Single-crystal structure analysis of a 1:1 adduct of 2 with nitromethane proved the molecular structure expected for a phthalimido-s-heptazine. DFT calculations were performed to obtain a better insight into the structural features of compound 2, especially the interaction of the carbonyl groups with the tri-s-triazine nitrogen atoms. The title compound 2 shows promising properties: it is thermally stable up to 500 °C in air and shows strong photoluminescence with a maximum emission at around 500 nm. The potential of the nucleophilic reaction of melem with other strong electrophiles provides new targets and prospects.

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Double insertion of carbon dioxide into the Si−N bonds of diaminosilanes of the type Me 2 Si(NRR′) 2 gives di(carbamoyloxy)silanes Me 2 Si[(OCO)NRR′] 2 . The reactions proceed exothermically and quantitatively in most cases. A comprehensive analysis of the CO 2insertion products including single-crystal X-ray structure analyses was carried out. Quantum chemical calculations indicate an activation energy of about 124 kJ/mol for both the first and the second insertion and support the exothermal nature of the reaction. Investigation of the thermal decomposition of the di(carbamoyloxy)silanes Me 2 Si[(OCO)NRR′] 2 reveals the formation of oligo-and polysiloxanes.Depending on the thermolysis parameters, isocyanates, amines, and/or ureas are formed in addition to the siloxanes. Various methods were applied to study the decomposition process and to identify and quantify the products, including thermal analyses, mass spectrometry, and FTIR and NMR (solution and solid-state) spectroscopy. The overall reaction scheme provides a novel route to polysiloxanes which uses carbon dioxide as an oxygen source.

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