Volume 70, Issue 2

2,3-Dihydro-4,5-diisopropyl-1,3-dimethylimidazol-2-ylidene ( 6 ) is prepared by reduction of the corresponding thion 7a with potassium. The selenium compound 7b is obtained from 6 and selenium. In the solid state, 7a and 7b exist as their isomers, as revealed by their crystal structures.

The reaction of Cu(II) nitrate with sodium 2-chlorobenzoate (NaL 1 ) and ( E )-1,2-di(pyridin-4-yl)ethene (dpe) yields a new complex [Cu(L 1 ) 2 (dpe)(H 2 O)] ( 1 ). When Zn(II) nitrate reacts with sodium 4-chlorobenzoate (NaL 2 ) and 1,2-di(pyridin-4-yl)ethane (dpa), [Zn(L 2 ) 2 (dpa)]·CH 3 OH ( 2 ) is obtained. Complexes 1 and 2 have been characterized by single-crystal X-ray diffraction, IR spectroscopy, and elemental and thermogravimetric analyses. 1 shows a 3D CdS network structure with uninodal 4-connected (6 5 .8) topology; complex 2 displays a chain structure.

RE Pd 5 Al 2 compounds with RE = Ce–Gd as well as Y and Lu have been previously synthesized. Although some compounds with the small lanthanides also exist, the compounds with intermediate-sized rare-earth elements ( RE = Tb–Yb) had not been prepared. We report on the missing members of the RE Pd 5 Al 2 ( RE = Tb–Yb) series as well as on the new RE Pt 5 Al 2 ( RE = Y, Gd–Tm, Lu) series, which we have synthesized and structurally as well as magnetically characterized. All members crystallize isostructurally in the ZrNi 2 Al 5 type with an anti -arrangement of the T = Pd/Pt and Al atoms. YPd 5 Al 2 and LuPd 5 Al 2 , as well as the respective platinum homologs, YPt 5 Al 2 and LuPt 5 Al 2 , have been characterized also by 27 Al magic-angle spinning nuclear magnetic resonance spectroscopy. Consistent with the XRD analysis, the spectra indicate the existence of only one distinct Al site in the structure.

The thf-complexed silanimine t Bu 2 Si=N–Si t- Bu 3 ·thf ( 1 (thf); monoclinic, space group C 2/ c ) was prepared by the reaction of 1 equivalent of t Bu 2 SiClN 3 with 1 equivalent of Na[Si t Bu 3 ] in Bu 2 O and subsequent addition of thf. By heating a benzene solution over a period of 11 d –140 °C, 1 (thf) slowly released the thf donor to form the uncomplexed silanimine 1 . However, under these conditions the silanimine 1 is unstable and is thermolized to give the ene reaction product of 1 with isobutene, H 2 C=C(CH 2 Si t Bu 2 –NH–Si t Bu 3 ) 2 . By contrast, the thermolysis reaction of Me 2 Si=N–Si t Bu 3 ·thf yielded the silanimine dimer (Me 2 SiNSi t Bu 3 ) 2 in 51 % and the vinyl ether Me 2 Si(OCH=CH 2 )NHSi t Bu 3 in 49 % yield.

The compound H 5 C 6 (H)Ge[C(GaCMe 3 )=C(H)CMe 3 ] 2 (μ-H) 3 [Ga(CMe 3 ) 2 ], 2 , was isolated in trace quantities from the reaction of Et 2 N–Ge(C≡C–CMe 3 ) 3 with excess H–Ga(CMe 3 ) 2 . Compound 2 has a unique molecular structure with a Ga 3 H 3 heterocycle of which one Ga–H–Ga group is bridged by a dialkenylgermanium unit. The molecular structure of a second compound ( 3 ) is reported, which may be described as a spiro -germane and has AlNGeC and AlC 2 Ge heterocycles. The rings are formed by intramolecular Al–N and Al–C interactions.

5,10-Disubstituted porphyrins are more recent additions to the family of meso-substituted porphyrins. A crystallographic comparison of 5,10-diphenylporphyrin with the regioisomeric 5,15-disubstituted system reveals striking differences in their conformation. In the free base porphyrins the former uses mainly out-of-plane distortion to alleviate steric strain while in-plane core elongation predominates in the latter. In contrast, the structure of the Cu(II) complex is planar and forms strong π-π aggregates with very small lateral shifts. Macroscopically, the packing is similar to that of porphyrin sponges of the 5,10,15,20-tetraphenylporphyrin type.

The preparation of six new 5,5′-azotetrazolates with organic cations is reported. Differential scanning calorimetry of all compounds showed exothermic decompositions. The crystal structures of the six 5,5′-azotetrazolates were determined by single-crystal X-ray diffraction analyses. The phase purities of the bulk samples were confirmed by Pawley fits of the experimental and calculated powder X-ray diffraction patterns.

The ternary aurides RE 4 Mg 3 Au 10 ( RE =Y, Nd, Sm, Gd–Dy) and their silver analogues were synthesized by induction melting of the elements in sealed niobium tubes. These intermetallic phases were characterized by powder X-ray diffraction. They crystallize with the Ca 4 In 3 Au 10 -type structure, which, from a geometrical point of view, is a ternary ordered version of Zr 7 Ni 10 with the rare earth and magnesium atoms ordering on the four crystallographically independent zirconium sites. The structures of crystals from three differently prepared gadolinium samples were refined from single-crystal X-ray diffractometer data: Cmca , a =1366.69(3), b =998.07(4), c =1005.54(3) pm, wR 2=0.0332, 1234 F 2 values, 46 variables for Gd 4.43 Mg 2.57 Au 10 , a =1378.7(1), b =1005.3(1), c =1011.2(1) pm, wR 2=0.0409, 1255 F 2 values, 48 variables for Gd 5.50 Mg 1.50 Au 10 , and a =1350.2(5), b =995.5(1), c =1009.3(1) pm, wR 2=0.0478, 1075 F 2 values, 48 variables for Gd 5.61 Mg 1.39 Au 10 . All crystals show substantial Mg/Gd mixing on two sites. The gold atoms form a pronounced two-dimensional substructure with Au–Au distances of 278 to 297 pm in Gd 4.43 Mg 2.57 Au 10 . These gold blocks are condensed via magnesium atoms (278–315 pm Mg–Au). The gadolinium atoms fill larger cavities within the three-dimensional networks. The magnesium vs. gadolinium site preference is a consequence of the different coordination numbers of the cation sites. All phases show homogeneity ranges RE 4+ x Mg 3– x Ag 10 and RE 4+ x Mg 3– x Au 10 . The influence of the synthesis conditions is briefly discussed.

Irradiation of tricarbonyl(η 5 -2,4-dimethyl-2,4-pentadien-1-yl)manganese ( 1 ) in tetrahydrofuran (THF) at 208 K affords the carmine solvent complex dicarbonyl(η 5 -2,4-dimethyl-2,4-pentadien-1-yl)(THF)manganese ( 2 ). Complex 2 thermally reacts with acetylene ( 3 ) to give tricarbonyl(η 3:2 -1,3-dimethyl-bicyclo[3.3.1]-3,6-nonadien-2-yl)manganese ( 4 ) and dicarbonyl(5-7,10-13-η-6,8-dimethyl-1,3,5,8,10,12-tridecahexaen-5-yl)manganese ( 5 ). The crystal structure of complex 4 was determined at room temperature [triclinic space group P1¯,$P\bar 1,$ a = 7.6891(9), b = 8.3860(8), c = 10.5252(13) Å, α = 93.000(9)°, β = 93.390(10)°, γ = 108.032(8)°, V = 642.43(13) Å 3 ]. The manganese atom is trigonal-bipyramidally coordinated by three carbonyl ligands, one ethenylic and one allylic fragment. Consequently, the bicyclic olefin ligand 1,3-dimethyl-bicyclo[3.3.1]-3,6-nonadiene coordinates the manganese atom in a η 3:2 mode. The constitution of complex 5 was deduced from IR data, elemental analysis, and 1 H NMR spectra. For the formation of complexes 4 and 5 , a reaction mechanism is proposed.

Extracting residues of an aqueous solutions containing equimolar amounts of K[C(CN) 3 ] and RbF or CsF, respectively, with absolute ethanol, yields triangular, transparent colorless crystals of Rb[C(CN) 3 ] and Cs[C(CN) 3 ] after the ethanol was allowed to evaporate. The compounds are isotypic and crystallize isopointal to calcite in space group R 3̅ c (no. 167) with the cell parameters a =809.9(1) and c =1461.3(3) pm and a =843.29(9) and c =1459.9(2) pm, respectively. Single crystals were used to record the Raman spectra of the title compounds.

Well-shaped single crystals of the europium(II) aluminate Eu 3 Al 2 O 6 were obtained as a side product during a synthesis attempt for EuCdAl. The structure was refined from single crystal X-ray diffractometer data of a twinned specimen: Ca 3 Al 2 O 6 type, Pa3¯,$Pa\bar 3,$ a = 1584.82(2) pm, wR = 0.0570, 2034 F 2 values, and 103 variables. All aluminium atoms in the Eu 3 Al 2 O 6 structure show tetrahedral oxygen coordination, and the AlO 4 tetrahedra (173–178 pm Al–O) are condensed via common corners to two-dimensional networks. The six crystallographically independent europium sites have coordination numbers 6, 7, 8, and 9, and their europium–oxygen polyhedra are linked with the AlO 4 tetrahedra to a dense packing. Bond-valence calculations reveal two sets of differently bonded europium atoms.