Syntheses and characterizations of alkyl- and amidotin porphyrin complexes: Molecular structure of trans-bis(phenylacetylido)(meso-tetra-p-tolylporphyrinato)tin(IV)

Treatment of (TTP)SnCl2 (TTP = meso-tetra-p-tolylporphyrinato dianion) with an excess of lithium amides (LiNHPh, LiNPh2, o-C6H4(NHLi)(2)) affords the metathesis products (TTP)Sn(NHPh)(2) (1), (TTP)Sn(NPh2)(2) (2), and (TTP)Sn(o-C6H4(NH)(2)) (3). Ligand exchanges of 1 with p-toluidine and 2,3,5,6-tetrafluoroaniline afford the complexes (TTP)Sn(p-NHC6H4Me)(2) (4) and (TTP)Sn(NHC6F4H)(2) (5), respectively. Treatment of (TTP)SnCl2 with the bulky lithium (2,4,6-tri-tert-butylphenyl)amide or with PhNLiNLiPh does not form the corresponding amido or azobenzene complexes but produces the reduced product (TTP)Sn. In addition, the reaction of (TTP)Sn(NHPh)2 with PhHN-NHPh results in the production of(TTP)Sn, azobenzene, and aniline. The diethyl complex (TTP)SnEt2 (6) can be prepared via the reaction of (TTP)SnCl2 with 1 equiv of ZnEt2. The dineopentyl complex (TTP)Sn(CH2CMe3)(2) (7) can be detected in the reaction of (TTP)SnCl2 with neopentyllithium. The methyl derivatives cis-(TTP)SnMe2 (8) and (TTP)SnMeBr (9) can be obtained by the treatment of (TTP)Li-2(THF)2 with 1 equiv of Me2SnBr2 at low temperature in toluene and CH2Cl2 respectively. Treatment of (TTP)SnCl2 with an excess of alkynyllithium salts (LiC=CPh, LiC=CSiMe3) affords the metathesis products (TTP)Sn(C=CPh)(2) (10) and (TTP)Sn(C=CSiMe3)(2) (11). Complexes 10 and 11 are inert at ambient temperature and are not photosensitive. Complex 10 reacts stepwise with excess MeOH cleanly to convert to (TTP)Sn(C=CPh)(OMe) (12) and then to (TTP)Sn(OMe)(2) (13) with increasing reaction time. The lability of the axial ligands in these tin porphyrin complexes correlates inversely with the basicity of the axial group. The crystal structure of 10 (monoclinic, P2(1)/c, a = 10.9424(2) Angstrom, b = 14.5565(5) Angstrom, c = 16.4968(6) Angstrom, alpha = 90 degrees, beta = 100.7930(10)degrees, gamma = 90 degrees, R-1 = 3.53%, and wR(2) = 8.90%) was determined from X-ray diffraction data.