ABSTRACT
The effect of high external pressures on the vibrational spectra of the tetraphenyl Group 14 compounds, Ph4M (M = Si, Ge, Sn, Pb), were examined between ambient pressure and 40 kbar with the aid of a diamond-anvil cell. The four compounds displayed similar behaviour as the pressure was increased and a structural transition at approximately 15 kbar, most probably associated with a phenyl ring rotation, was identified in each case. The pressure dependencies of selected vibrational modes were obtained.
Subject(s)
Organometallic Compounds/chemistry , Organosilicon Compounds/chemistry , Spectrophotometry, Infrared/methods , Spectrum Analysis, Raman/methodsABSTRACT
Solid-state, CP-MAS, 119Sn NMR spectra were measured for a series of para-substituted triaryltin(pentacarbonyl)manganese(I) complexes. All the spectra show an asymmetric sextet due to spin-spin coupling and second-order quadrupolar effects, transmitted by dipolar coupling between the 119Sn and 55Mn nuclei, which are not suppressed by magic-angle rotation. The solid-state 1JMn-Sn spin-spin and nuclear quadrupole coupling constants range from 130 to 250 Hz and -8 to 21 MHz, respectively, and show an inverse linear correlation, which is attributed to the dominance of the Fermi contact contribution to the 1JMn-Sn coupling. The tris(p-methylthiophenyl)tin derivative is an exception, attributed to a difference in crystal structure from the other complexes. The magnitudes of the principal elements of the 119Sn chemical shift tensors were determined and appear to be strongly influenced by the ring torsion angles and the para-substituents of the phenyl rings. Solid-state 119Sn NMR spectroscopy provides a useful method of probing the electronic environment around the tin and manganese nuclei in transition metal complexes. Copyright 1998 Academic Press.
