Cristian S. Campos-Fernández

A One-Pot, High-Yield Synthesis of a Paramagnetic Nickel Square from Divergent Precursors by Anion Template Assembly**

A paramagnetic Ni-containing molecular square has been synthesized in high yield from divergent precursors. An X-ray structure (shown in the picture) reveals the presence of an encapsulated tetrafluoroborate anion, which appears to be a requisite condition for the formation of the cyclic oligomer.

Reactivity studies of 2,3,5,6-Tetra(2-pyridyl) pyrazine (tppz) with first-row transition metal ions

Reactions of 2,3,5,6-tetra(2-pyridyl) pyrazine (tppz) with [ML 6 ][X] 2 (L = CH 3 CN, H 2 O; X = [BF 4 ] - , [ClO 4 ] - , [NO 3 ] - [BArF] - (BArF - B[3.5-C 6 H 3 (CF 3 ) 2 ] 4 ) lead to the high-yield formation of mononuclear [M(tppz) 2 ] 2 + , (M = Mn I I , Fe I I , Co I I , and Ni I I ) and dinuclear [Ni 2 (tppz)(CH 3 CN) 6 ] 4 + species. The new compounds were fully characterized by X-ray crystallographic, spectroscopic, and magnetic susceptibility measurements. Surprisingly, the 2:1 M:tppz reactions did not lead to isolation of the dinuclear species except in the case of Ni(II). It was further noted that even in the case of the Ni reactions, the nuclearity of the product depends on the choice of anions and the reaction conditions. Magnetic measurements of the mononuclear species [Co(tppz) 2 ] 2 + revealed thermally induced spin-crossover behavior from a high-spin S = 3/2 at higher temperatures to a low-spin S = ½ complex at lower temperatures. The dinuclear compound [Ni 2 (tppz)(CH 3 CN) 6 ] 4 + exhibits a weak antiferromagnetic interaction through the bridging tppz ligand.

Mit hoher Ausbeute verlaufende Eintopfsynthese eines paramagnetischen Nickelquadrats durch Anionentemplat‐gesteuerten Selbstaufbau

Ein Tetrafluoroborat-Ion dient als Templat bei der Synthese eines paramagnetischen molekularen Nickelquadrats und bleibt danach im Hohlraum eingeschlossen (siehe Struktur im Kristall). Mit anderen Templat-Ionen gelang die Synthese nicht.

Coupling dirhodium units through terpyridine bridges: synthesis and structure of a novel molecular rectangle

The cation [Rh2(μ-O2CMe)2(MeCN)6]2+ reacts with the bis-terpyridine ligand 2,3,5,6-tetra-2-pyridylpyrazine (tppz) to yield the reduced compound [Rh4(μ-O2CMe)2(tppz)2(MeOH)4]4+ whose structure is that of molecular rectangle with edges defined by short Rh–Rh and long Rh–tppz–Rh units.