Synthetic, Spectroscopic, and Electrochemical Studies of the Isomerically-Rich [M(CO)(2)(P(2)P')X](+/0) (M = Mn, Re; X = Cl, Br; P(2)P' = eta(3)-Ph(2)P(CH(2))(2)P(Ph)(CH(2))(2)PPh(2)) System: Structural Characterization of a Novel Pair of Diastereoisomers of cis,mer-Re(CO)(2)(P(2)P')Cl.