MAGNETIC-RESONANCE SPECTROSCOPIC STUDIES OF A TETRAARYL-DISTANNENE AND TETRAARYL-DIGERMENE [M2R4] (R = C6HBUT-2-ME-3-4,5,6 AND M = SN OR GE)

Tin-119 NMR spectral studies in the solid state and in solution of [Sn 2R4] (R = C6HBu'-2-Me-3-4,5,6) 3 are presented. The ambient temperatur e Sn-119 CP-MAS NMR spectrum displayed a single resonance at delta(iso ) 819, while variable-temperature spectra in toluene clearly indicated the existence of a rapid equilibrium between the loosely held dimer 3 and its monomer SnR2. Photolysis of either 3 or its digermanium analo gue in benzene yielded the persistent radicals [MR3](.) (M = Ge or Sn) , which were studied by ESR spectroscopy. The ESR parameters are compa red with other trialkyl-and triamido-tin(III)- and -germanium(III)-cen tred radicals. Noteworthy is the first observation of C-13 hyperfine c oupling for a Group 14 metal-centred radical, 18(1) G for [SnR3](.) an d 10(1) G for [GeR3](.).