The complexes [(DMPP)(2)M(CH3CN)(2)]X-2 (DMPP = 3,4-dimethyl-1-phenylphosphole; M = Pd, Pt; X = BF4-, NO3- ClO4-) react with 2 equiv of the dienophiles N,N-dimethylacrylamide (DMAA), 2-vinylpyridine (VyPy), and diphenylvinylphosphine (DPVP) to form bis-[4+2] Diels-Alder cycloaddition products. The [M(DMPP)(2)-(DMAA)(2)](2+) and [M(DMPP)(2)(VyPy)(2)](2+) complexes form exclusively as the cis-geometric isomers, whereas for [M(DMPP)(2)(DPVP)(2)](2+), both cis- and trans-geometric isomers are formed. The two Diels-Alder cycloadditions occur sequentially, and the absolute configuration of the first reaction influences the absolute configuration of the second. In all cases, racemic mixtures of the (R,R) and (S,S) diastereomers are formed; none of the meso (R,S) diastereomer is observed. New complexes were characterized by elemental analyses, physical properties, infrared spectroscopy, H-1,H-1{P-31}, C-13{H-1}, and P-31{H-1} NMR spectroscopy, and, in most cases, X-ray crystallography.