Crystal Structures of Manganese and Cobalt Dichloride Monohydrate and Deuteration Effects on Magnetic Behavior

Abstract

This work reports the long sought crystal structures of the title members of the intriguing series of 3d transition metal dichloride monohydrates. The double chain structure which results from rearrangement of the well-known pseudo-octahedral coordination geometry and single chains in the corresponding metal chloride dihydrate is extremely unusual. MnCl2·H2O and CoCl2·H2O each crystallize in orthorhombic space group Pnma with Z = 4 and lattice parameters a = 9.0339(1), 8.8207(3); b = 3.68751(5), 3.5435(1); c = 11.5385(2), 11.2944(4) all in Å and for Mn, Co, respectively. Results are reported also for both fully deuterated systems; the structures remain the same with lattice parameter changes typically much less than 0.1%. Various magnetic properties of MnCl2·D2O and CoCl2·D2O are reported. For the latter, there are no apparent differences, qualitatively or quantitatively, from the previously measured properties of CoCl2·H2O. Interestingly, for the former some differences with respect to MnCl2·H2O are apparent, principally a lower Tmax = 3.10(10) K about which a broad antiferromagnetic maximum is centered, and a larger value χmax = 0.336(3) emu/mol. However, antiferromagnetic ordering appears to occur at essentially the same 2.18(2) K. Results of fits to susceptibilities of MnCl2·D2O and CoCl2·D2O are compared with those obtained before for MnCl2·H2O and CoCl2·H2O. Structural considerations serve to rationalize the physical properties, especially the lower dimensional magnetism of monohydrates.

Light-Driven Proton Reduction in Aqueous Medium Catalyzed by a Family of Cobalt Complexes with Tetradentate Polypyridine-Type Ligands

“…This aqua ligand forms a hydrogen bond with a solvated water molecule providing a hydrogen bonding network that is expected if [Co­( 3 )­(OH 2 )­Cl] + is dissolved in an aqueous environment. An important structural feature among these complexes is a Co–Cl bond that is considerably longer (2.4–2.6 Å) than the Co–Cl bonds found in diimine or dioxime Co complexes (2.2–2.3 Å) and closer to the Co–Cl bond distance in CoCl 2 (2.44–2.51 Å). , The long Co–Cl bond lengths endow these bonds with more ionic than covalent character and may facilitate dissociation of a chloride ligand from the cobalt complex in a protic solvent such as water. All Co–N bond distances lie in a narrow range of 2.0–2.1 Å, regardless of whether the N-donor is part of a pyridine, phen, or quinoline moiety.…”

“…The bromogroup was converted to acetyl through a Stille-type coupling with 1-ethoxyvinyl tri-n-butylstannane, followed by hydrolysis of the resulting vinyl ether. A second Friedlander condensation with 8-aminoquinoline-7-carbaldehyde provided the bridged ligands 38,39 The long Co−Cl bond lengths endow these bonds with more ionic than covalent character and may facilitate dissociation of a chloride ligand from the cobalt complex in a protic solvent such as water. All Co−N bond distances lie in a narrow range of 2.0−2.1 Å, regardless of whether the N-donor is part of a pyridine, phen, or quinoline moiety.…”

Visible Light-Driven Hydrogen Evolution from Water Catalyzed by A Molecular Cobalt Complex

“…These bond lengths are even longer than the Co−Cl bonds in cobalt dichloride that have been reported to range from 2.44 to 2.51 Å. 31,32 To the extent that the Co−Cl bonds have greater ionic character, they may account for better water solubility and more facile hydration, both important features for an effective homogeneous PRC. The N−Co−N bond angles of 6 are consistent with the metal ion being contained in either a fivemembered (83.1°and 81.7°) or a six-membered (92.9°) chelate ring.…”

Synthesis, Crystal Structure and Properties of a new Hydrate of Manganese Thiocyanate with the Composition Mn(NCS)2(H2O)2

“…However, an additional hydrate with the composition MnCl 2 (H 2 O) is reported that shows an unusual structure, in which each Mn 2+ cation is octahedrally coordinated by one water molecule and five chloride anions. As it is the case for the dihydrate, the Mn 2+ cations are linked by μ‐1,1‐bridging chloride anions into chains, that are linked by μ‐1,1,1‐chloride anions to MnCl 2 double chains (Figure S3) [32] . If the water molecules are formally removed, these chains condense into the layered structure of MnCl 2 (Figure S3) [33] …”

“…As it is the case for the dihydrate, the Mn 2 + cations are linked by μ-1,1-bridging chloride anions into chains, that are linked by μ-1,1,1-chloride anions to MnCl 2 double chains (Figure S3). [32] If the water molecules are formally removed, these chains condense into the layered structure of MnCl 2 (Figure S3). [33]…”