The 35Cl and 79,81Br NQR spectra of (C5H5)2M Hal2 (M = Ti, Mo, W, Zr, Hf; Hal = Cl, Br) are similar. They are quadruplets with splittings ranging from 2 to 7%. The averaged frequencies of chlorine and bromine are related by a linear dependence. The temperature dependence of 81Br in Cp2HfBr2 (in the range of 77 ≑ 224 K.) is of conventional character with frequencies slowly changing with temperature; phase transitions have not been observed.
Regularities of transmission of the effect of equatorial and axial substituents were established for a number of chlorine-containing organic compounds of pentavalent phosphorus using 35C1 NQR spectra. The field constants of 35C1 NQR frequencies of the chlorine atoms participating in the P--Ci bond were estimated for a series of tetrahedral phosphorus ions. The 35CI NQR frequencies of chlorine atoms in tetraeoordinated ions of pentavalent phosphorus and in analogous i~leetronic silicon compounds are related by a linear dependence.Key words: 3sCI NQR spectra, field constant of NQR frequency, chlorine-containing organic compounds of pentavalent phosphorus.Peculiarities of the geometry of pentavalent phosphorus compounds have been studied for long. t It was reliably established that the molecules of these compounds have, as a rule, a trigonal-bipyramidal configuration with the P atom at the center and, if one of the substituents is eliminated as an anion or becomes a constituent of a complex anion, the remaining cation is transformed into a tetrahedron with the central P atom. However, peculiarities of redistribution of the electron density and local electric fields in the molecules of pentavalent phosphorus compounds and corresponding ions have not been studied in detail as yet.Nuclear quadrupole resonance (NQR) spectroscopy of halogen atoms provides a unique possibility to trace systematic changes in the mutual influence of substituents in a series of similar molecular and ionic forms of halogen-containing organic compounds of pentavalent phosphorus. This work is dedicated to the study of the transmission of substituent effects through the molecular skeleton of organophosphorus compounds whose molecules contain a P--CI bond; the conclusions drawn are based on the data on changes in the 35C1 NQR frequencies.The goals of this work were: (i) to reveal correlations between the spectral and structural characteristics of compounds under study; (ii) tQ find quantitati_v_e relationships of the transmission of substituent effects to axial and equatorial positions with respect to the nature, number; and positions of substituents in molecular forms of pentavalent phosphorus compound~; (iii) to compare the transmission of substituent effects in tetrahedral ions Deceased.
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