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We have studied the origin of the cooperative Jahn-Teller effect in PrCu 2 . We have determined the anisotropic phase diagram by measuring the thermal expansion and the magnetostriction in magnetic fields up to 15 T. The Jahn-Teller transition temperature is almost constant for the field along the a- and c -axis, while it decreases with increasing the field along the b -axis. The phase diagram can be explained qualitatively by including the quadrupolar interaction for 〈O xy 〉 in the crystalline electric field Hamiltonian.

Four simple salts and six complex salts of TCNQ\ewdot radical anion with N,N-dialky1-1,3-dichalcogenacycloalkan-2-iminium cations, (Remark: Graphics omitted.) and (Remark: Graphics omitted.) (n=2 or 3, Y=S or Se, R=Me or Et) were prepared. The electrical resistivity of (Remark: Graphics omitted.) (1.1×104 ohm cm) was more than 10 times lower than other three simple salts ((6.1–8.7)×105 ohm cm). Electronic absorption spectra and magnetic susceptibilities suggest that the latter three involve dimeric (TCNQ)22−, while in the former the interaction between two TCNQ\ewdot radical anions is weak in the solid state. All the complex salts with compaction samples exhibited the resistivity of 2.4–4.0 ohm cm with very low activation energies (0.018–0.087 eV). Electronic spectra and magnetic susceptibilities show that the interaction between two TCNQ\ewdot radical anions decreases owing to the implication of neutral TCNQ.

Following 10 simple and complex salts of TCNQ\ewdot with N,N-disubstituted 1,3-dithiolan-2-iminium cations; (Remark: Graphics omitted.) (n=1 when R1=R2=n-Pr, n-C6H13, n-C8H17, Ph, and R1=Me and R2=Ph; n=2 when R1= R2=n-Pr, n-Bu, Ph, and R1=Me and R2=Ph), and (Remark: Graphics omitted.) were prepared. Of these, simple salt (Remark: Graphics omitted.) was obtained in two different crystalline forms; unstable violet needles and green plates. All the salts as compacted samples displayed semi-conducting behaviors in the 20–90 °C range. Electrical resistivities of the 1:2 complex salts fell in the range of 5–90 ohm cm at 25 °C, while the simple and 2:3 complex salts showed much large resistivities (the order of 103–109 ohm cm). The measurements of electronic absorption spectra and magnetic susceptibilities indicated that the simple salts in the solid state involve dimeric (TCNQ)22−, except for the green salt of (Remark: Graphics omitted.) which consists of the iminium cation and discrete TCNQ\ewdot radical anio...

A series of carbamato-silver(I) complexes having the formula of MePh2PAg(YZCNR2) (1), (Ph3P)2Ag(YZCNR2) (2), (MePh2P)2Ag(YC(O)NR2) (3), Ph3PAg(YC(O)NR2) (4) (YZ = SS, SSe, SeSe; Y = S, Se; R = Me, Et) and (Ph3P)3Ag2(SC(O)NEt2)2 (5) were prepared. Molecular-weight determinations, conductivity measurements, 1H and 31P NMR spectra indicate that 1 exists as a planar three-coordinate complex involving a bidentate carbamato ligand in solution. The complexes 2 and 3 dissociate into the phosphorus ligand and Ph3PAg(YZCNR2) or MePh2PAg(YC(O)NR2) to considerable extents in solution. On the other hand, 4 exists as an equilibrium mixture of monomeric and oligomeric species in solution. The addition of extra Ph3P to a solution of 4, causes the formation of the bis-phosphine complex, (Ph3P)2Ag(YC(O)NR2), which is a predominant species in solution containing three equivalent amounts of Ph3P at low temperature. It is also concluded that 3, 4 and 5 have less tendencies to exist as disilver(I) species in solution than the copper(I) analogs.

A series of the compounds of formula [M(PR3)2 (XYCNMe2)][Me2SnCl3] (M = Pd(II) and Pt(II); PR3 = PPh3 and PMePh2; X, Y = Se) has been prepared. Conductivity measurements, i.r. and PMR spectra indicate that the complexes are 1:1 electrolytes in solution and the cationic part takes a square planar configuration. The 1H and 31P NMR spectra reveal that abilities of the sulfur and selenium to coordinate with the metal(II) resemble each other closely. The bonding nature of the PR3 Pd(II) and -Pt(II) bonds is also described on the basis of the 31P N MR spectra.