Five- and six-coordinate hydridorhodium(III) complexes containing metalated Schiff-bases as ligands

The reactions of either [RhCl(C8H14)2]2 (2) or [RhCl(C2H4)2]2 (3) with Schiff-bases 1a–d derived from 2-aminopyridine afford, in the presence of four equivalents of PiPr3, the octahedral chloro(hydrido)rhodium(III) complexes [{(C5H4N)NC(C6H4R)}RhHCl(PiPr3)2] (4a–d) in which the metalated Schiff-base behaves as a chelating ligand. Treatment of 4a (RH) with NaI and CF3SO3Tl produce the corresponding derivatives [{(C5H4N)NC(C6H5)}RhHX(PiPr3)2] (5, 6) by salt metathesis. The triflato compound 6 reacts with nBu4NF · xH2O to give [{(C5H4N)NC(C6H5)}RhHF(PiPr3)2] (7). While attempts to eliminate HCl from 4a failed, the reaction of 4a with AgPF6 generates the five-coordinate cationic complex [{(C5H4N)NC(C6H5)}RhH(PiPr3)2]PF6 (8) which adds one equivalent of acetonitrile to give [{(C5H4N)NC(C6H5)}RhH(NCCH3)(PiPr3)2]PF6 (9). Treatment of 4a with either nBu2Mg or LiAlH4 affords the dihydridorhodium(III) compound [{(C5H4N)NC(C6H5)}RhH2(PiPr3)2] (10) being also accessible from 8 and nBu2Mg.