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The solvent-free reaction of terbium metal with an imidazole melt (C 3 H 4 N 2 , ImH) yields single-crystalline ∞ 3 [Tb(Im) 3 ]@NH 3 (Im -) C 3 H 3 N 2 -, imidazolate anion) and hydrogen. Both N atoms of the imidazolate rings coordinate η 1 to terbium cations, thereby forming a homoleptic three-dimensional network. The Tb 3+ ions exhibit complete nitrogen coordination, resulting in trigonal prisms as coordination polyhedra and C.N. ) 6. The network contains cavities large enough to take up NH 3 molecules, the latter formed by the partial decomposition reaction of the amine ligand in the melt reaction. Ammonia can be removed thermally or over time without decomposition of the network. Unsubstituted imidazole can thus be utilized for crystal engineering and the formation of rare earth amide network structures. The compound exhibits an amazingly strong green emission. The emission spectrum shows the typical Tb 3+ f-f transitions; additionally, an efficient ligand f Tb 3+ energy transfer is observed.

The dehydration of Ca(SCN)2∙4H2O yields single crystals of Ca(SCN)2 ∙ 2 H2O as well as of Ca(SCN)2. Ca(SCN)2 ∙ 2 H2O crystallizes with a hitherto unknown structure (orthorhombic, Pnma, Z = 4, a = 1280.1(2), b = 790.3(1), c = 726.9(1) pm, Rall = 0.0430). The Ca2+ ions are surrounded by four SCN− ions and four water molecules. The polyhedra are connected to chains along [010] via common oxygen atoms. The SCN− ions connect these chains to a three-dimensional network so that each thiocyanate group is linked to two Ca2+ ions. Hydrogen bonding with sulfur atoms as acceptors is observed. The crystal structure of Ca(SCN)2 (monoclinic, C2/c, Z = 4, a = 961.7(2), b = 642.4(2), c = 787.2(2) pm, Rall = 0.0673) consists of alternating layers of Ca2+ and SCN− ions. The cations are surrounded by four sulfur and four nitrogen atoms in form of a square antiprism. According to 3∞[Ca(SCN)8/4] each SCN− ion connects four Ca2+ ions with each other. Thermal investigations show a phase transition of Ca(SCN)2 ∙ 4 H2O followed by dehydration to Ca(SCN)2 which finally decomposes yielding CaS. IR and Raman measurements have been performed and the resulting frequencies assigned and discussed.

Transmetalation of the potassium methanide complex, K{CH(PPh2NSiMe3)2}, with [(Ph3P)2CuI] afforded the corresponding copper complex [{CH(PPh2NSiMe3)2}CuPPh3] (1), whereas the reaction of K{CH(PPh2NSiMe3)2} with [Ph3PAuCl] resulted in the dinuclear gold complex [(Ph3PAu)2{C(PPh2NSiMe3)2}] (2). The solid-state structure of 1 shows the formation of a six-membered metallacycle (N1-P1-C1-P2-N2-Cu) that has a twist boat conformation. In contrast, compound 2 is an alpha,alpha-diaurated species, in which the two gold atoms are coordinated in a linear fashion onto the ligand backbone. Photoluminescence measurements show that the latter compound has a strong violet emission.

Single crystals of K2Mg2(SCN)6·3H2O were obtained by the reaction of the binary compounds MgCl2·xH2O and KSCN at 220° using the Bridgman technique. The compound crystallizes hexagonally with the noncentrosymmetric space group P63 cm (Z = 2, a = 885.2(1) pm, c = 1732.7(3) pm, R1all = 0.1035). In the crystal structure, the Mg2+ ions are coordinated by oxygen and nitrogen atoms while the K+ ions are exclusively surrounded by sulfur atoms. The two crystallographically different Mg2+ ions are linked via common nitrogen atoms to dimers, [Mg2(SCN)6(H2O)3]2-. The K+ ions are connected with each other by two crystallographically different sulfur atoms to hexagonal rings which form layers in the (001) plane. The dimers are connected to these layers in equal orientation leading to the absence of inversion symmetry. Frequency doubling measurements on K2Mg2(SCN)6·3H2O as well as on KDP powder samples were carried out. The second harmonic generation intensity of the rhodanide is about 40% of that of KDP. Furthermore, IR and Raman measurements were performed, and the results were compared to other thiocyanates. The energies of the vibrations of the molecular SCN- ions demonstrate their bridging function in the crystal structure, and the energies and the shapes of the H2O bands indicate hydrogen bonds.

Frau Professor Marianne Baudler zum 80. Geburtstag gewidmet Inhaltsu È bersicht. Die Reaktion von BaCl 2 und NaSCN fu È hrte zu Einkristallen von BaClSCN (P 2 1 /m, Z = 2, a = 588,6(1) pm, b = 465,8(1) pm, c = 864,4(2) pm, b = 100,20(3)°, R all = 0,0214). Die Verbindung kristallisiert mit einer neuen Struktur, in der sich entlang [001] anionische Schichten von SCN ± und Cl ± abwechseln. Die SCN ± -Ionen koordinieren die Ba 2+ -Ionen sowohl u È ber die N-als auch u È ber die S-Atome. Auch Na 4 Mg(SCN) 6 (P 3 1c, Z = 2, a = 863,8(1) pm, c = 1399,3(2) pm, R all = 0,0870), dargestellt aus NaSCN und MgCl 2 , kristallisiert mit einer Schichtstruktur. Zwischen die Anionenschichten werden abwechselnd entweder Na + -Ionen oder Na + -Ionen und Mg 2+ -Ionen eingebaut. Betrachtet man nur die C-Atome der SCN ± -Ionen, so bilden diese eine hexagonal dichteste Kugelpackung, in der 5/6 aller Oktaederlu È cken durch Kationen besetzt sind.

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We have investigated how secondary phases appear and disappear upon increasing europium concentration from 1.5 to 16.2 atom % in standard strontium borophosphate phosphate phosphor, Sr 6 BP 5 O 20 , using X-ray diffraction and photoluminescence and photoluminescence excitation measurements both at room temperature and at 80 K. In standard phosphor, a minor phase of strontium phosphate, Sr 3 ͑PO 4 ͒ 2 , was detected besides the main component Sr 6 BP 5 O 20 . With increasing Eu concentration, the phase Sr 3 ͑PO 4 ͒ 2 disappears and new phases of Sr 3 Eu͑PO 4 ͒ 3 , SrBPO 5 , and Sr 2 P 2 O 7 are formed. Sr 3 Eu͑PO 4 ͒ 3 is observed to be the major phase in 16.2 atom % samples. It contains only trivalent europium. An attempt has also been made to understand the origin of these secondary phases and their significance for the performance of this luminescent material. This study shows how X-ray diffraction technique and photoluminescence spectroscopy can be used in a complementary manner to explore the phase composition of the materials.