No abstract

Complexes have been formed between bivalent ions of cobalt, nickel, copper, zinc, mercury, and palladium and the the ligands 4,4'-dicarboxyethyl-3,3',5,5'-tetramethyldipyrromethene (mpmH) and 3,4'-dicarboxyethyl-5-chloro-3',4,5'-trimethyldipyrromethene (cpmH). The stereochemistry of these complexes has been investigated by measurement of magnetic susceptibility, and l H n.m.r. spectra, and U.V. visible spectra. An X-ray determination of the crystal and molecular structure of the complex Pd(mpm), is reported. The palladium atom lies on a crystallographic centre of symmetry and is necessarily coplanar with the four co-ordinated nitrogen atoms of the ligand. The unique bidentate ligand is not planar.THE stereochemistry of transition-metal complexes of dipyrromethenes has been much discussed. Porter,l who reported the preparation of bis(dipyrr0methene) complexes of the divalent ions of cobalt, nickel, palladium, copper, zinc, cadmium, and mercury concluded that steric interactions between groups in the 5-and 5'positions (I) precluded square planar stereochemistry for the metal ions. f 11Recent work has established that some metal ions will achieve tetrahedral configurations in order to overcome intermolecular steric repulsions. from studies of u.v.-visible spectra and magnetism, that It has been t Part I, J. E. Fergusson and C.

This change is very rapid for the blue isomer, but relatively slow for the purple isomer.) The weight gained in the formation of the yellow complex, which is identical with the weight loss when the yellow complex is dehydrated to re-form the original blue or purple complexes, corresponds to three molecules of water per Ni(II) ion (Caled: 14.11. Found: 13.9). This yellow complex can be tentatively formulated as ( ) 4( 20)2• 2 . It is significant that in the vibrational spectrum of this complex, the water absorptions are more intense and much broader than those observed in the 307 complex formed in ethanol solution, (I)NiCl4(H20)2, which contains two molecules of coordinated water only.Characterization of the Complexes. The complexes prepared were characterized by analysis, visible and infrared spectra (30,000-250 cm-1), and magnetic susceptibility measurements. For details, see ref 15.

This paper proposes and presents the design and implementation of an underlay communication channel (UCC) for 5G cognitive mesh networks. The UCC builds its waveform based on filter bank multicarrier spread spectrum (FB-MC-SS) signaling. The use of this novel spread spectrum signaling allows the device-to-device (D2D) user equipments (UEs) to communicate at a level well below noise temperature and hence, minimize taxation on macro-cell/small-cell base stations and their UEs in 5G wireless systems. Moreover, the use of filter banks allows us to avoid those portions of the spectrum that are in use by macro-cell and small-cell users. Hence, both D2D-to-cellular and cellular-to-D2D interference will be very close to none. We propose a specific packet for UCC and develop algorithms for packet detection, timing acquisition and tracking, as well as channel estimation and equalization. We also present the detail of an implementation of the proposed transceiver on a software radio platform and compare our experimental results with those from a theoretical analysis of our packet detection algorithm.

Trifluoroacetyl fluoride dimerizes at -108°in the presence of CsF to form CF3CO2C2F0. With (CFsfiCFO--Cs+, COF2, CF3C(0)F, C2FóC(0)F, and C3F7C(0)F react to form the heptafluoroisopropyl esters, FCC>2CF(CF3)2, CF3C02CF(CF3)2, 02 0020 (0 3)2, and C3F7C02CF(CF3)2. Although these compounds are formed only at low temperature, when pure they are stable at 25°and above.