The reaction between CuCl(2).2H(2)O and disodium terephthalate, Na(2)tp, in aqueous solution simultaneously produces chain, bis(aqua)[&mgr;-(terephthalato-kappaO:kappaO')]copper(II), monohydrate, Cutp(OH(2))(2).H(2)O (1), and layered, bis(aqua)[&mgr;-(terephthalato-kappaO)]copper(II), Cutp(OH(2))(2) (2), structured materials. 1 (C(8)H(10)CuO(7)) belongs to the orthorhombic P2(1)2(1)2 space group [a = 6.3015(4) Å, b = 6.8743(4) Å, c = 22.9972(14) Å, and Z = 4] and incorporates tp in a bridging bis-monodentate binding mode and Cu(II) in a tetragonally elongated octahedron. 2 (C(8)H(10)CuO(6)) which belongs to the orthorhombic Pmc2(1) space group [a = 10.7421(8) Å, b = 7.2339(10) Å, c = 5.7143(13) Å, and Z = 2] incorporates tp in a mono-bidentate binding mode and Cu(II) in a distorted square pyramid. 1 and 2 exhibit axial X-band powder EPR spectra with g( perpendicular) = 2.08, g( parallel) = 2.29 (1) and g( perpendicular) = 2.07, g( parallel) = 2.29 (2) at 300 K. 1 obeys the Curie-Weiss law at high temperatures (theta = -7.2 K) and at low temperatures behaves as 1-D magnetic chains with an exchange-coupling constant of J/k(B)= -9.15 K (H = -2JS(1).S(2)). This material displays a spontaneous moment below 2 K under small applied magnetic fields, consistent with the presence of spin canting. 2 exhibits ferromagnetic interactions with theta = +0.8 K. Along the 1-D chain where coordinated water forms the bridge between metal centers, the coupling between Cu(II) is J/k(B) = +0.6 K. The fit of the magnetic susceptibility for 2 using a molecular field correction, which takes into consideration antiferromagnetic interactions between chains via the tp ligand, yields J'/k(B) = -0.13 K.

Two new organically templated U(IV) fluorides, (C 5 H 14 N 2 ) 2 U 2 F 12 ‚2H 2 O (AU1-1) and (C 2 H 10 N 2 )U 2 F 10 (AU2-1), have been prepared from the reaction of UO 3 with HF and homopiperazine (C 5 H 12 N 2 ) at 200 °C in aqueous media. These compounds have been characterized by single-crystal X-ray diffraction, elemental analysis, and magnetic susceptibility measurements. Crystallographic data: AU1-1, monoclinic, space group P2 1 /c, a ) 9.272(4) Å, b ) 12.314(4) Å, c ) 18.475(7) Å, β ) 90.32(3)°, Z ) 4; AU2-1, monoclinic, space group C2/c, a ) 16.038(8) Å, b ) 7.131(3) Å, c ) 8.782(4) Å, β ) 91.75(4)°, Z ) 4. AU1-1 consists of face-sharing UF 9 tricapped trigonal prisms that form one-dimensional chains that further hydrogen-bond with diprotonated homopiperazine and water molecules. AU2-1 forms, in part, from the cleavage of homopiperazine to yield diprotonated ethylenediamine, which serves to template the formation of uranium fluoride layers. These layers consist of edge-and corner-sharing UF 9 tricapped trigonal prisms. The variable-temperature magnetic susceptibility of AU1-1 is consistent with antiferromagnetic interactions between U(IV) centers, with µ eff (300 K) ) 4.37 µ B /f.u. and θ ) -1.3 K. The magnetization of AU1-1 at 2 K displays an irreversible metamagnetic-like transition at H c ) 3.60 T. The magnetic susceptibility for AU2-1 (µ eff (300 K) ) 4.58 µ B /f.u.) with θ ) +21 K suggests the presence of weak ferromagnetic interactions within the [U 2 F 10 ] 2layers.

Electrical transport and magnetic properties have been measured for the family of ternary rare-earth transition-metal antimonides RE 3 TiSb 5 (RE ) La, Ce, Pr, Nd, Sm). Single-crystal X-ray structures have now been determined for all members of this series. All are metallic, with anomalies appearing in the resistivity curves suggestive of electronic transitions. La 3 -TiSb 5 , Ce 3 TiSb 5 , and possibly Nd 3 TiSb 5 undergo transitions to a superconducting state below ∼4 K. Support for the existence of a superconducting phase is also provided by onset of diamagnetism in the magnetization behavior below T C . Extended Hu ¨ckel band structure calculations disclose strongly anisotropic electrical conductivity, reflecting the onedimensional character of covalent bonding within the structure, and reveal the presence of narrow Ti-based bands close to the Fermi level.

To elucidate the mechanism of the reaction between V 0 (C 6 H 6 ) 2 and tetracyanoethylene (TCNE) that leads to the room-temperature magnet V[TCNE]] x ‚yCH 2 Cl 2 (x ∼2; y ∼ 1 / 2 ), reactions between bis(arene)-vanadium (arene ) 1,3,5-trimethylbenzene, 1,3,5-tri-tert-butylbenzene) and its cations and TCNE and its anion were studied. The reaction of V o (arene) 2 with TCNE yields magnets with critical temperatures ranging from 28 to 400 K. Products from the reaction of [V I (arene) 2 ] + with [TCNE] •-were not magnets; however, reaction of [V I (arene) 2 ] + with [TCNE] •-in the presence of TCNE forms a magnetically ordered material. The reaction of V 0 (1,3,5-C 6 H 3 Me 3 ) 2 with 2 equiv of one-electron oxidant [Fe III (C 5 H 5 ) 2 ] + , and subsequently with [TCNE] •-, also leads to a magnetic material. The results of these investigations suggest that V 0 (arene) 2 undergoes two one-electron oxidation reactions with TCNE to form sequentially [V I (arene) 2 ] + and "[V II (arene) 2 ] 2+ ", the latter being the key intermediate that reacts with [TCNE] •-to produce the magnetic product. [V I (arene) 2 ] + has been isolated, whereas and "[V II (arene) 2 ] 2+ " has not. The one-electron oxidation of V 0 [C 6 H 3 (t-Bu) 3 ] 2 with Ag-[BPh 4 ] produces {V I [C 6 H 3 (t-Bu) 3 ] 2 } + [BPh 4 ] -. The stoichiometric reaction of V 0 [C 6 H 3 (t-Bu) 3 ] 2 with TCNE leads to paramagnetic {V I [1,3,5-C 6 H 3 (tBu) 3 ] 2 } + [TCNE] •-. {V I [C 6 H 3 (t-Bu) 3 ] 2 } + [BPh 4 ] -and {V I [1,3,5-C 6 H 3 -(tBu) 3 ] 2 } + [TCNE] •-have been structurally characterized. When [V II (NCMe) 6 ]{B[3,5-C 6 H 3 (CF 3 ) 2 ] 4 } 2 is reacted with [TCNE] •-, a route that does not use bis(arene)vanadium complexes, a magnetic precipitate is also produced. As established earlier, the reaction of Cr 0 (arene) 2 with TCNE forms nonmagnetically ordered [Cr I (arene) 2 ] •+ -[TCNE] •-. Reaction of lower oxidation potential Cr 0 Np 2 (Np ) naphthalene) with TCNE putatively forms "[Cr II Np 2 ] 2+ " which reacts with [TCNE] •-to form Cr[TCNE] x ‚yS, which was isolated and, unexpectedly, does not magnetically order. Similar results are obtained when [Cr II (NCMe) 4 ][BF 4 ] 2 or [Cr II (NCMe) 6 ][B(3,5-C 6 H 3 (CF 3 ) 2 ) 4 ] 2 is reacted with [n-Bu 4 N][TCNE].