Ekk Sinn

Crystal structures of A2FeCl5⋅H2O (A=Rb+, Cs+) and field dependent superconducting susceptometer measurements

Crystal structures and low field principal crystal axis magnetic measurements are reported for the antiferromagnetic iron (III) salts A2FeCl5⋅H2O; A=Rb+, Cs+. The two compounds undergo a zero field paramagnetic to antiferromagnetic phase transition at 6.5 K (A=Cs+) and 10.05 K (A=Rb+). The spin flop magnetic phase is observed in high field measurements. The magnetic field‐temperature phase diagrams are reported. All magnetic measurements were recorded on a superconducting susceptometer. The bicritical points are 6.25 K, 14.5 kOe (A=Cs+), 9.75 K, 17.8 KOe (A=Rb+). Crystal data for Cs2FeCl5⋅H2O: space group Cmcm, Z=4, a=7.442(3) A, b=17.307(7) A, c=8.077(7) A, V=1040 A3, R=5.2%, 561 reflections. Crystal data for Rb2FeCl5⋅H2O, space group Pnma, Z=4, a=13.825(4) A, b=9.918(3) A, c=7.100(2) A, V=4.9 A3, 5.7%, 712 reflections.

Nickel(II) complexes of some quadridentate Schiff-base ligands-II. Infrared spectra

Abstract The infrared spectra (4000-200cm−1) of a series of nickel(II) complexes of Schiff bases formed by the condensation of 5-chloro-2-hydroxybenzophenone and some alkanediamines, H2N(CH2)nNH2 (n = 2–12), has been investigated. The nickel62 isotope substitution method has been used to help identify the metal sensitive vibrations.

Comparison of complexes with anionic and neutral amide groups. Crystal and molecular structures of bis N-(2-pyridyl)acetamide complexes of Pd(II), Ni(II) and Zn(II)

Abstract The crystal structure of the neutral complex Pd(aap)2 of the title ligand shows a tetragonal Pd(II) with two trans ligands each chelated by the ring nitrogen and amide oxygen. The amide nitrogen is deprotonated and not coordinated. In the isomorphous M(aapH)2(NO3)2 structures where M = Co(II), Ni(II), and Zn(II), there are two axial water molecules and again two trans ligands chelated as above but with a neutral amide nitrogen. For two of these complexes (M = Ni, Zn), the detailed molecular structures were determined. These complexes possess an amide CO bond 0.04 A shorter and an amide CN bond 0.03 A longer than are found in the Pd(aap)2 complex. Crystal data for Pd(aap)2: space group P21/n, Z = 2, a = 8.191(2), b = 4.859(1), c = 17.582(3) A, β = 96.24(2)°, R = 3.2% for 1728 reflections. Crystal data for [Zn(aapH)2(H2O)2](NO3)2: space group P21/n, Z = 2, a = 7.134(3), b = 10.266(6), c = 14.004(6) A, β = 93.13(4)°, R = 6.0% for 1714 reflections. Crystal data for [Ni(aapH)2(H2O)2](NO3)2: space group P21/n, Z = 2, a = 7.120(2), b = 10.170(2), c = 13.970(5) A, β = 93.61(2)°, R = 3.2% for 1787 reflections. Crystal data for [Co(aapH)2(H2O)2(NO3)2: space group P21/n, Z = 2, a = 7.113(6), b = 10.275(4), c = 14.045(7) A, β = 93.6(1).

SUBSTITUTED PHENANTHROLINES AND THEIR METAL CHELATES

Substituents at and adjacent to the nitrogen atoms in 2,2?-bipyridyl and 1,10-phenanthroline are most likely to cause drastic changes in the magnetic properties of complexes with these ligands. Complexes of the N-oxides (2,2?-bipyridine 1,1?-dioxide, and 1,10-phenanthroline 1- oxide) with copper, and of 2-substituted phen (substituent = Cl, CONH2) with iron(II) are investigated, and a new one-step reaction to convert phno into cphn is reported. The copper complex Cu(bpyo)Br2 shows antiferromagnetic interactions, but other complexes Cu(bpyo)X2 (X = Cl, NO3) with this ligand are magnetically normal, as are Cu(phno)Cl2 and Cu(phno)Br2. The complex [Fe(cphn)3] (ClO4)2 lies near the high spin-low spin crossover for iron(II), and its magnetic moment is normal at room temperature but falls with decreasing temperature. The dioxide of phen appears not to be formed by the literature method and no successful synthesis can be reported here.

Mono- and di-selenium complexes of chromium. Syntheses and crystal structures of (η5-C5H5)2Cr2(CO)4Se and (η5-C5H5)2Cr2(CO)4Se2

The reaction of dicyclopentadienylhexacarbonyldichromium with elemental selenium at ambient temperature provides a simple route to (η5-C5H5)2Cr2(CO)4Se (1) and (η5-C5H5)2Cr2(CO)4Se22 in high yields.

Synthesis and properties of molybdenum(VI) peroxo compounds with imidazole and the X-ray structure of (C3H5N2)2[O{MoO(O2)2H2O}2], a novel imidazolium peroxo complex containing a μ-oxo bridged dimer

Abstract Crystalline peroxo molybdate(VI) complexes with imidazole are reported: (C3H5N2) 2[O{MoO(O2)2H2O}2] (1), MoO2(O2)(C3H4N2)2H2O (2) and K2MoO2(O2)2 (C3H4N2)4H2O (3). They represent the first peroxo metal compounds containing imidazole. IR spectra display characteristic ν(MoO) between 967 and 955 cm−1, and ν(OO) between 892 and 853 cm−1. The X-ray crystal structure of (1) shows the presence of a μ-oxo group bridging two pentagonal bipyramidal {MoO(O2)2H2O} moieties, each hydrogen bonded to an essentially planar imidazolium cation via one of the oxygens of a coordinated peroxo group.

Low temperature magnetic properties of the bimetallic compounds [Co(C5H5NO)6](MX4) (M = Co2+, Zn2+; X = Cl-, Br-)

Abstract We have measured the specific heat and suceptibility of the compounds [Co(C 5 H 5 NO) 6 ] (MX 4 ) (M = Co, Zn; X = Cl, Br), which are all isostructural and monoclinic. The data show that two magnetic subsystems are present in the Co/Co compounds. The Co 2+ ions on the octahedral positions of the chlorine compounds exhibit antiferromagnetic ordering at T c = 0.95(1) K, the Co 2+ ions on the tetrahedral positions remaining paramagnetic down to at least 0.04 K. The paramagnetic ions appear to experience two different molecular fields from the ordered Co 2+ ions. The behaviour of the bromine compounds is similar, the ordering temperature being about 0.65 K. Both chlorine compounds are apparently canted antiferromagnets. The bromine compounds show compensated antiferromagnetism.

Structural and magnetic properties of Co(urea)2Cl2⋅2H2O: A two‐dimensional Ising system with hidden canting

The characterization of Co(urea)2Cl2⋅2H2O is reported. The crystal structure at ambient temperatures yields the following information: the chlorine, water, and urea group are coordinated, the urea being bound via the oxygen, to form an octahedral environment about the metal atom. Intermolecular hydrogen bonds between the coordinated chlorine and water ligands produce parallel infinite sheets which provide a two‐dimensional exchange pathway. The sheets are separated by the urea ligands and may be considered as magnetically isolated from one another. Crystal data: space group P21/c, Z = 2, a = 7.397 (3) A, b = 7.795(1) A, c = 9.764(2) A, β = 116.23(5) A, V = 505 A3, ρcalc = 1.87 g cm−3, ρobs = 1.88 g cm−3, R = 4.1% for 692 reflections. A λ anomaly in the specific heat was observed at 2.585±0.005 K, and the critical parameters are characteristic of the two‐dimensional Ising model. The zero‐field susceptibilities have been measured over the temperature interval 1.2–30 K, and are consistent with antiferromagne...

Properties and Structures of the Five-Coordinated Copper(II) and High-Spin Nickel(II) Complexes of 3,3'-Dichloro-2,2'-(1,12-diphenyl-2,6,11-triazadodeca-1,11-diene-1,12-diyl)bisphenol

Crystals of acetato(methanethio1ato)-gamma-picolinemercury(II), MeSHg02CMe,C6H7N (1), are monoclinic, P21/a, a 16.617(9), b 7.271(3), c 20.476(2), beta = 113.31(5), Z 8. The structure resembles that of its pyridine analogue, being based on a polymeric (-Hg-SMe-)n chain with acetate and picoline groups coordinated at each mercury; a similar structure is found for EtSHg02CMe,C5H5N (2), monoclinic, P21/c, a 9.344(2), b 17.917(9), c 7.179(2) A, beta 106.24(3), Z 4. The structure of tetrachlorotetra(2-methylpropane-2-thiolato)di(gamma-picoline)tetramercury(11), (ButS)4CI4Hg4(C6H7N)2 (3), also resembles that of its pyridine analogue being based on an unusual tetranuclear grouping of mercury atoms linked by chloride and thiolate bridges. Crystals of (3) are monoclinic, P21/c a 12.334(7), b 17.468(9), c 9.999(5) A, beta 91.18(4), Z 2. Crystals of MeSHgBr (4) are monolinic, P21/c, a 7.770(9), b 7.500(5), c 7.945(10) A, beta 91.71(3), Z 4, and contain parallel chains (-Hg-SMe-)n with neighbouring chains linked by bridging bromine atoms into parallel sheets. Each bromine is triply bridging, being coordinated to two mercury atoms in one chain, and one mercury atom in an adjacent chain. The structure of MeSHgCl appears to be isomorphous.

Magnetic ordering in [Co(γ-Ch3C5H4NO)6](ClO4)2: I. Crystal structure and superexchange pathways

Abstract The crystal structure of the title compound is reported, where the ligand is γ-methylpyridine N-oxide. The crystal data are: space group P 2 1 / c , Z = 2, a = 9.498(2) A , b = 10.761(3) A , c = 20.523(7) A , and β = 92.46(2)° . The structure consists of octahedrally-coordinated [Co(γ-CH3C5H4NO)6]2+ ions in a largely two-dimensional network, together with perchlorate ions which exhibit two-fold positional disorder. Likely superexchange paths are discussed.