Catalyst-substrate adducts in asymmetric catalytic hydrogenation. Crystal and molecular structure of (((R,R)-1,2-bis(phenyl-o-anisoylphosphino)ethane)(methyl (Z)-. beta. -propyl-. alpha. -acetamidoacrylate))rhodium tetrafluoroborate, (Rh(DIPAMP)(MPAA))BF sub 4

(Rh(R,R-DIPAMP)(MeOH){sub 2}){sup +} (DIPAMP = 1,2-bis(phenyl-o-anisoylphosphino)ethane), which serves as an asymmetric hydrogenation catalyst for enamides, reacts with methyl (Z)-{beta}-propyl-{alpha}-acetamidoacrylate (MPAA) to form the 1:1 adduct, (Rh(R,R-DIPAMP)(MPAA)){sup +} (1), with a binding constant of 1.4 {times} 10{sup 4} M{sup {minus}1} at 25{degree}C. Crystals of the BF{sub 4} salt of the predominant diastereomer of 1 were isolated and subjected to single-crystal X-ray analysis. The structure of 1 resembles those deduced previously for rhodium ((1,2-bis(diphenylphosphino)ethane)(methyl(Z)-{alpha}-acetamidocinnamate))tetrafluoroborate and rhodium ((2S,3S)-2,3-bis(diphenylphosphino)butane(ethyl (Z)-{alpha}-acetamideocinnamate)) perchlorate.