Trigonal Bipyramidal M2Ch32- (M = Sn, Pb;Ch = S, Se, Te) and TlMTe33- Anions: Multinuclear Magnetic Resonance, Raman Spectroscopic, and Theoretical Studies, and the X-ray Crystal Structures of (2,2,2-crypt-K+)3TlPbTe 33--·2en and (2,2,2-crypt-K+) 2Pb2Ch Journal Articles