The bromine-rich zinc bromides Zn6Br12(18-crown-6)2×(Br2)5 (1), Zn4Br8(18-crown-6)2×(Br2)3 (2), and Zn6Br12(18-crown-6)2×(Br2)2 (3) are prepared by reaction of ZnBr2, 18-crown-6, and elemental bromine in the ionic liquid [MeBu3N][N(Tf)2] (N(Tf)2 = bis(trifluoromethylsulfonyl)amide). Zn6Br12(18-crown-6)2×(Br2)5 (1) is formed instantaneously by the reaction. Even at room temperature, compound 1 releases bromine, which was confirmed by thermogravimetry (TG) and mass spectrometry (MS). The release of Br2 can also be directly followed by the color and density of the title compounds. With controlled conditions (2 weeks, 25 °C, absence of excess Br2) Zn6Br12(18-crown-6)2×(Br2)5 (1) slowly releases bromine with conconcurrent generation of Zn4Br8(18-crown-6)2×(Br2)3 (2) (in ionic liquid) and Zn6Br12(18-crown-6)2×(Br2)2 (3) (in inert oil). All bromine-rich zinc bromides contain voluminous uncharged (e.g., Zn3Br6(18-crown-6), Zn2Br4(18-crown-6)) or ionic (e.g., [Zn2Br3(18-crown-6)](+), [(Zn2Br6)×(Br2)2](2-)) building units with dibromine molecules between the Zn oligomers and partially interconnecting the Zn-containing building units. Due to the structural similarity, the bromine release is possible via crystal-to-crystal transformation with retention of the crystal shape.

The reaction of manganese(ii) bromide and the crown ether 18-crown-6 in the ionic liquid [(n-Bu)3MeN][N(Tf)2] under mild conditions (80-130 °C) resulted in the formation of three different coordination compounds: MnBr2(18-crown-6) (), Mn3Br6(18-crown-6)2 () and Mn3Br6(18-crown-6) (). In general, the local coordination and the crystal structure of all compounds are driven by the mismatch between the small radius of the Mn(2+) cation (83 pm) and the ring opening of 18-crown-6 as a chelating ligand (about 300 pm). This improper situation leads to different types of coordination and bonding. MnBr2(18-crown-6) represents a molecular compound with Mn(2+) coordinated by two bromine atoms and only five oxygen atoms of 18-crown-6. Mn3Br6(18-crown-6)2 falls into a [MnBr(18-crown-6)](+) cation - with Mn(2+) coordinated by six oxygen atoms and Br - and a [MnBr(18-crown-6)MnBr4](-) anion. In this anion, Mn(2+) is coordinated by five oxygen atoms of the crown ether as well as by two bromine atoms, one of them bridging to an isolated (MnBr4) tetrahedron. Mn3Br6(18-crown-6), finally, forms an infinite, non-charged [Mn2(18-crown-6)(MnBr6)] chain. Herein, 18-crown-6 is exocyclically coordinated by two Mn(2+) cations. All compounds show intense luminescence in the yellow to red spectral range and exhibit remarkable quantum yields of 70% (Mn3Br6(18-crown-6)) and 98% (Mn3Br6(18-crown-6)2). The excellent quantum yield of Mn3Br6(18-crown-6)2 and its differentiation from MnBr2(18-crown-6) and Mn3Br6(18-crown-6) can be directly correlated to the local coordination.

The chain-like polynuclear coordination compounds (ZnBr2)n(18-crown-6)2 (n = 4, 6, 8, 10) and [Zn5Br9][N(Tf)2] are obtained by reacting ZnBr2, SnBr4 and 18-crown-6 in the ionic liquid [(n-Bu)3MeN][N(Tf)2] (N(Tf)2: bis(trifluoromethylsulfonyl)imide). Structurally, chain-like anionic building units with corner- and edge-sharing ZnBr4/Zn(Br,O)4 tetrahedra of increasing lengths are obtained for (ZnBr2)n(18-crown-6)2. In contrast, [Zn5Br9][N(Tf)2] exhibits a cationic [Zn5Br9(18-crown-6)2](+) building unit with distorted tetrahedral, trigonal-bipyramidal and octahedral coordination of Zn(2+). Besides the coordination of Zn(2+) to Br(-), Zn(2+) is partially coordinated by 18-crown-6 with unusual folding of the crown-ether molecule. In sum, the polynuclear Zn-Br chains can be considered as intermediates between the finite [ZnBr4](2-) anion and the infinite solid ∞(3)[ZnBr2]. The addition of the Lewis-acid SnBr4 turned out to be essential for product formation and results in a Br(-) subtraction from ZnBr2. The coordination compounds are characterized based on structure analysis, thermogravimetry and energy-dispersive X-ray analysis.

The phosphorus interhalides [PBr][IBr] (1) and [PBr][IBr] (2) were prepared by reaction of PBr and the interhalogen IBr in the ionic liquid [MeBuN][N(Tf)] (N(Tf): bis(trifluoromethylsulfonyl)amide). [PBr][IBr] (1) consists of tetrahedral [PBr] cations and linear [IBr] anions. [PBr][IBr] (2) also contains [PBr] cations as well as the iodine bromide anion [IBr]. The latter represents the yet largest known polyiodinebromide. Moreover, (2) shows remarkable halogen release (IBr and Br) of 96.8 wt% below 300 °C. For the ternary system P-Br-I, (1) and (2) are the first compounds that were characterized by crystal structure analysis. Composition, bonding situation and properties were further validated by energy dispersive X-ray (EDX) analysis, thermogravimetry (TG) and Raman spectroscopy.