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Research is presented concerning the simultaneous crystallization of two forms of the linear trinuclear compound Co3(dpa)4Cl2. The use of X-ray studies to observe the tetragonal and orthorhombic forms is discussed.

Thirteen tetranuclear mixed-metal complexes of the hexaimine macrocycle (LPr)6- have been prepared in a one-pot 3:1:3:3 reaction of copper(II) acetate hydrate, the appropriate lanthanide(III) nitrate hydrate, 1,4-diformy1-2,3-dihydroxybenzene (1), and 13-diaminopropane. The resulting family of copper(II)--lanthanide(III) macrocyclic complexes has the general formula CuII₃LnIII(LPr)- (NO₃)₃solvents (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Tb, Ho, Er, Tm, or Yb). X-ray crystal structure determinations carried out on [Cu₃Ce(LPr)(NO₃)₃(MeOH)₃] and [Cu₃Dy(LPr)(NO₃)₃(MeOH)₃] confirmed that the large Lnm ion is bound in the central O₆ site and the three square pyramidal CuIIions in the outer N₂O₂ sites (apical donor either nitrate anion or methanol molecule) of the Schiff base macrocycle. Only die structurally characterized Cu₃Tb complex, reported earlier, is a single-molecule magnet (SMM): the other 12 complexes do not exhibit an out-of- phase ac susceptibility signal or hysteresis of magnetization in a dc field. Ab initio calculations allowed us to rationalize the observed magnetic properties, including the significant impact of subde chemical modification on SMM behavior. Broken-symmetry density functional theory (BS-DFT) calculations show there is a subde structural balance as to whether the Cu...Cu exchange coupling is ferro- or antiferromagnetic. Of the family of 13 magnetically characterized tetranuclear CuII₃LnIII macrocyclic complexes prepared, only the TbIII complex is an SMM: the theoretical reasons for this are discussed. [ABSTRACT FROM AUTHOR]

Examines the tuning of the metal-metal bonds in the linear tricobalt compound Co[sub 3](dpa)[sub 4]Cl[sub 2]. Bond-stretch and spin-state isomers; Determination of the sixteen crystal structures; Structure refinement; Compounds containing axial ligands other than chlorine; Chromium analogue.

Describes three trichromium compounds that differ from but are akin to trichromium compounds. Linear trichromium complexes with the anion of 2,6-di(phenylimino)piperidine; Linear chain of three chromium atoms in an unsymmetrical fashion; Orientation of the phenyl groups; Pairs of diamagnetic quadruply bonded chromium units.

Reports that the reaction of the linear tricobalt compound Co3(dpa)4Cl2 (dpa = di(2-pyridyl)amide) with silver hexafluorophosphate in acetonitrile has yielded [(Co3(dpa)4(CH3CN)2][F6]2 (2). Production of a monoclinic form 2.CH3CN.2Et2O and a triclinic form, 2.3CH3CN; Symmetrical tricobalt units in both crystals.

Reports on the completion of the series M2(hpp4Cl2 complexes (hpp is the anion of 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) from M = W to M = Pt. Preparation and characterization of those with M = W, Os and Pt; Bond order of 1, based on a configuration in which only the sigma* orbital is empty.

Investigates the characterization of the bonding of linear trichromium (Cr3) complexes containing Cr3(dipyridylamide)43+ cores. Identification of unsymmetrical chain of Cr3 atoms; Determination of chromium to chromium distances of the complexes; Utilization of magnetic susceptibility measurements on two different compounds.

Examines the characterization of linear trichromium (Cr3) complexes containing Cr3(dipyridylamide)42+ cores. Identification of anionic ligands at each end of the Cr36+ chain; Determination of symmetrical and unsymmetrical arrangement in the Cr3 atoms; Analysis of the chromium to chromium distances; Flexibility of the Cr3 arrangement.