Multinuclear magnetic resonance study of the dilead trichalcogenide anions Pb2SnCh3-n2- (Ch = Se or Te), Pb2SSeTe2-, and M2Se32- (M = Sn and/or Pb) and the crystal structures of (2,2,2-crypt-K+)2Sn2Te32- and (2,2,2-crypt-K+)2Sn2Se32- Journal Articles