Dibromidobis(3,5-dimethyl-1H-pyrazole-κN 2)cobalt(II)

In the mononuclear title complex, [CoBr2(C5H8N2)2], the CoII atom is coordinated by two N atoms from two monodentate 3,5-dimethyl­pyrazole ligands and two Br atoms in a highly distorted tetra­hedral geometry. In the crystal, the complex mol­ecules are linked by inter­molecular N—H⋯Br hydrogen bonds into chains along [101]. An intra­molecular N—H⋯Br hydrogen bond is also present

Diaqua­bis­(pyridine-2-carboxyl­ato-κ2 N,O)manganese(II) dimethyl­formamide hemisolvate

There are two crystallographically independent complex mol­ecules with very similar geometries in the unit cell of the title compound, [Mn(C6H4NO2)2(H2O)2]·0.5C3H7NO. The central ion is situated in a distorted octa­hedral environment of two N- and four O-donor atoms from two pyridine-2-carboxyl­ate ligands and two cis-disposed water mol­ecules. The carboxyl­ate ligands are coordinated in a chelate fashion with the formation of two five-membered rings. In the crystal, the complex mol­ecules are connected by O—H⋯O hydrogen bonds between the coordinated water mol­ecules and the uncoordinated carboxyl­ate O atoms, thus forming hydrogen-bonded walls disposed perpendicularly to the bc plane

fac-Tris(pyridine-2-carboxyl­ato-κ2 N,O)cobalt(III)

In the title compound, [Co(C6H4NO2)3], the CoIII ion lies on a threefold rotation axis and is in a distorted octa­hedral environment defined by three N and three O donor atoms from three fac-disposed pyridine-2-carboxyl­ate ligands. The ligands are coordinated in a chelate fashion, forming three five-membered rings. In the crystal, translationally related complex molecules are organized into columns along [001] via C—H⋯O hydrogen bonds

Field evolution of the spin-liquid candidate YbMgGaO4

We report magnetization, heat capacity, thermal expansion, and magnetostriction measurements down to mK temperatures on the triangular antiferromagnet YbMgGaO$_4$. Our data exclude the formation of the distinct $\frac13$-plateau phase observed in other triangular antiferromagnets, but reveal plateau-like features in second derivatives of the free energy, magnetic susceptibility and specific heat, at $\mu_0H$ = 1.0 - 2.5 T for $H\parallel{}c$ and 2 - 5 T for $H\perp{}c$. Using Monte-Carlo simulations of a realistic spin Hamiltonian, we ascribe these features to non-monotonic changes in the magnetization and the $\frac12$-plateau that is smeared out by the random distribution of exchange couplings in YbMgGaO$_4$

cis-Bis(2,2′-bipyridine-κ2 N,N′)bis­(dimethyl sulfoxide-κO)zinc bis­(tetra­phenyl­borate) dimethyl sulfoxide monosolvate

In the mononuclear title complex, [Zn(C10H8N2)2(C2H6OS)2](C24H20B)2·C2H6OS, the ZnII ion is coordinated by four N atoms of two bidentate 2,2′-bipyridine mol­ecules and by the O atoms of two cis-disposed dimethyl sulfoxide mol­ecules in a distorted octa­hedral geometry. The S atom and the methyl groups of one of the coordinated dimethyl sulfoxide mol­ecules are disordered in a 0.509 (2):0.491 (2) ratio. The crystal packing is stabilized by C—H⋯O hydrogen bonds between the dimethyl sulfoxide solvent mol­ecules and tetra­phenyl­borate anions