O-Phenylenediamine and related complexes of chromium, vanadium and manganese

Abstract

Using the ligands (L–L)o-phenylenediamine, 4,5-dimethyl-o-phenylenediamine and phenanthrene-9,10-diamine, anionic chromium(III) complexes of the type [CrCl4(L–L)]–, have been isolated as quaternary phosphonium salts from interaction of CrCl3(thf)3(thf = tetrahydrofuran) and the ligand in the presence of [PPh4]Cl or [PPh3(CH2Ph)]Cl. Interaction in the absence of quaternary phosphonium salts gives [CrCl2(L–L)2]Cl. A similar tetrachloro anion has been obtained using the chelating phosphine 1,2-(HPriP)2C6H4. Similar complexes obtained from VCl3(thf)3 have the form [VCl4(L–L)]– and [VCl2(L–L)2]Cl. Use of the dihalides leads to octahedral complexes trans-MCl2(L–L)2(M = V or Cr) and trans-MnI2(L–L)2. The interaction of [P(CH2Ph)Ph3][CrCl4{(H2N)2C6H2Me2}] with AgO3SCF3 and of [CrCl2{(H2N)2C6H4}2]Cl with trifluoromethanesulfonic acid and diethyl ether leads to the unusual chromium(IV) octahedral triflate compounds Cr(NH2)(O3SCF3)3[(H2N)2C6H2Me2] and Cr(O3SCF3)4[(H2N)2C6H4], respectively. The crystal structures of the compounds [PPh3(CH2Ph)][CrCl4{(H2N)2C6H4}], Cr(NH2)(O3SCF3)3[(H2N)2C6H2Me2], Cr(O3SCF3)4[(H2N)2C6H4] and [PPh4][VCl4{(H2N)2C6H2Me2}] have been determined. All have octahedral structures with chelating diamines. In the tetrachlorochromate(III) salt, the Cr–N distances are ca. 0.05 A longer than those in the chromium(IV) compounds. The VIII–N distances [2.16(1)A] are ca. 0.05 A longer than the CrIII–N distances [2.11(1)A], as expected, but the vanadium complex shows a much greater diffrence in M–Cl distances trans to N [2.336(4)A] or trans to Cl [2.381(4)A] than in the chromium(III) complex [all 2.342–2.356(5)A].