Structure and Magnetism of a New Hydrogen-Bonded Layered Cobalt(II) Network, Constructed by the Unprecedented Carboxylate−Phosphinate Ligand [O₂(C₆H₅)PCH₂CO₂]^2-

Abstract

By hydrothermal reaction of CoCl2 x 6H2O with K2pcc (H2pcc = phenyl(carboxymethyl) phosphinic acid) at 423 K, a novel hybrid material of formula [Co2(pcc)2 (H2O)2] x H2O has been obtained. The compound, which is the first pcc/metal complex reported, exhibits a polymeric arrangement, where cobalt metal ions, linked together by bridging carboxylate and phosphinate oxygens, form infinite chains of edge-shared CoO6 octahedra. The cobalt chains are in turn linked together through important hydrogen-bonding interactions, which create an infinite 2D architecture. The two crystallographically independent cobalt centers, both displaying distorted octahedral coordination, present different environments as one is surrounded by six ligand oxygens and the other by four ligand oxygens and by two water oxygens. Careful magnetic studies performed by a home-built alternating current susceptometer reveal that the system undergoes an antiferromagnetic transition below 2.0 K leading to a canted structure. Field-dependent studies further indicate the occurrence of a metamagnetic transition at a critical field of 650 +/- 50 G.

Origin and spectroscopic determination of trigonal anisotropy in a heteronuclear single-molecule magnet

“…The efficiency of this recently-developed synthetic route for the isolation of pure heterometallic species was here further confirmed by measuring the ac susceptibility of a powder sample of 1 in the range 0.03-60 kHz with a home developed probe based on the Oxford Instruments MAGLAB platform. 45 The results revealed a unique peak in the χ" vs. frequency plots, (See Figure S1 in and hexagonal prism habitus were mounted on a goniometric head and investigated at 100 K with an Xcalibur3 (Oxford Diffraction) diffractometer using Mo K α radiation ( λ = 0.71073 Å). The compound is isomorphic with its tetrairon(III) analogue 23 and crystallizes in trigonal space group R 3 c with unit cell parameters a = b = 16.1435(11) Å and c = 57.073(2) Å (hexagonal setting).…”

Molecular Engineering for Single‐Chain‐Magnet Behavior in a One‐Dimensional Dysprosium–Nitronyl Nitroxide Compound

“…The ac magnetic susceptibility was measured by using a homemade probe operating in the range 20-20 000 Hz. [19] Crystal structure data were collected with an Oxford Diffraction Xcalibur3 diffractometer.…”

A New Cobalt(II)‐Layered Network Based on Phenyl(carboxymethyl) Phosphinate

“…The pcc decomposition starts at 200°C, whereas the Cu and Co pcp anhydrous networks are stable up to 340°C. [12][13][14] …”

“…We note that the overall magnetic behaviour of complex 1, dominated by single ion effects, is substantially different to that reported for the parent pcc derivative. [14] The magnetic behaviour of the latter is due to moderate intrachain ferromagnetic coupling and correspondingly increased dipolar interactions, that result in the complex undergoing a long-range magnetic (antiferromagnetic) transition around 2 K. On the contrary both zero field cooling/field cooling measurements and AC measurements excluded the existence of long-range magnetic order in 1. The difference in the magnetic behaviour between the two compounds is not surprising however, as, in the case of the pcc derivative, the coupling was transmitted by a Co-O-Co bridge, whereas in complex 1 the exchange involves a Co-O-C-O-Co path in syn/anti conformation.…”

“…Now we are extending our investigations to the anion phenyl(carboxymethyl) phosphinate (pcc, Scheme 2 [14] Herein we present our results on a new derivative of the formula [[Co(pcc)(4,4Ј-bipy)(H 2 O)](H 2 O) 1.5 ] n (1). 1 was prepared by the reaction of CoCl 2 ·4H 2 O with K 2 pcc in the presence of the 4,4Ј-bipy auxiliary ligand.…”