Upon reaction of Rh-I(Hdmg)(2) (Hdmg = dimethylglyoximato monoanion) with phosphines of small cone angle, such as PEt(3), PBu(3)(n), and PPh(2)Me, an oxime group of one of the two equatorial dimethylglyoximato ligands is converted into an imine group. The reaction product is the [Rh-III(Hdmg)(Hbdio)(PR(3))(2)](+) complex, where the ligands Hdmg and Hbdio (Hbdio = 2,3-butanedione 2-imine 3-oximato) are bound to Rh(III) through four nonequivalent nitrogen atoms and the two phosphines are in trans positions. The asymmetry of the equatorial moiety is also reflected in the inequivalence of the phosphine phenyls in the NMR spectra of [Rh(Hdmg)(Hbdio)(PPh(2)Me)(2)](+). The complex [Rh(Hdmg)(Hbdio)(PEt(3))(2)](+) [Rh(Hdmg)(2)(Cl)(2)](-).H2O crystallizes in the space group P ($) over bar 1 with cell parameters a = 8.181(3) Angstrom, b = 11.245(4) Angstrom, c = 11.579(5) Angstrom, alpha = 92.16(2)degrees, beta = 94.47(2)degrees, gamma = 98.67(2)degrees. The structure was refined to final R = 0.033 using 4690 independent reflections. The solution of the structure revealed that the crystal is built up by anions [Rh(Hdmg)(2)(Cl)(2)]-, disordered cations [Rh(Hdmg)(Hbdio)(PEt(3))(2)](+), and water molecules of crystallization in the ratio 1:1:1. The cation binds one H2O molecule through two hydrogen bonds involving the adjacent oxime O and imine N atoms. Polarographic and CV studies show that the product of the monoelectronic reduction of [Rh(Hdmg)(Hbdio)(PEt(3))(2)](+) loses a phosphine and the Rh(I) species obtained by further reduction reacts with the Rh(III) starting compound to give a Rh(II) species.