Molecular Structures of Ge(tpp)(OAc)₂ and In(tpp)(OAc) and Their Implications:  Correlations between the ¹³C NMR Chemical Shift of the Acetato Ligand and Different Types of Carboxylate Coordination in M(por)(OAc)_n {por = tpp (5,10,15,20-Tetraphenylporphyrinate), tmpp (5,10,15,20-Tetrakis(4-methoxyphenyl)porphyrinate), tpyp (5,10,15,20-Tetrakis(4-pyridyl)porphyrinate); M = Ga, In, Tl, Ge, Sn; n = 1, 2}

In this work, we determine the crystal structure of bis(acetato)(meso-tetraphenylporphyrinato)germanium(III), Ge(tpp)(OAc)₂. Experimental results indicate that the germanium atom has an octahedral coordination geometry. The geometry around the germanium center of the Ge(tpp)(OAc)₂ molecule has Ge−O(1) = 1.874(5) Å and an average Ge−N = 1.999 Å. The acetate groups are unidentately coordinated to the germanium(IV) atom. In the title compound, (acetato)(meso-tetraphenylporphyrinato)indium(III), In(tpp)(OAc), the coordination sphere of the In³⁺ ion is an approximately square-based pyramid in which the apical site is occupied by an asymmetric (chelating) bidentate OAc^- group. The average In−N bond distance is 2.173(3) Å, and the In atom is displaced 0.762 Å from the porphyrin plane. The In−O(1) and In−O(2) distances are 2.322(4) and 2.215(4) Å, respectively. To develop the correlations between the ¹³C chemical shifts of the acetato ligand and types of carboxylate coordination, this work also thoroughly examines the ¹³C NMR data of the methyl and carbonyl carbons on 13 acetato porphyrinato metal complexes M(por)(OAc)_n with n = 1, 2, por = tpp, tmpp (5,10,15,20-tetrakis(4-methoxyphenyl)porphyrinate), tpyp (5,10,15,20-tetrakis(4-pyridyl)porphyrinate), and M = Ga, In, Tl, Ge, Sn. According to these results, the ¹³C methyl and carbonyl chemical shifts of the acetato group at 24 °C are separately located at 20.5 ± 0.2 and 168.2 ± 1.7 ppm for the acetate, which is unidentately coordinated to the metal (i.e., the unidentate case) and at 18.0 ± 0.7 and 175.2 ± 1.6 ppm for the chelating bidentate case.