Tin(IV) and organotin(IV) derivatives of anionic 4-acyl-5-pyrazolonato ligands: synthesis, spectroscopic characterization (IR, far-IR, 119Sn mössbauer, 1H, 13C and 119Sn NMR) and behavior in solution crystal and molecular structure of trans-diphenylbis[1-phenyl-3-methyl-4-(4-bromobenzoyl) -pyrazolon-5-ato]tin(IV) | Publicación