We have investigated the primary charge separation reactions in two Rhodobacter capsulatus bacterial reaction center (RC) mutants that have multiple mutations near the L-side bacteriochlorophyll (BChl(L)) and bacteriopheophytin (BPhL) cofactors. Both RCs contain the "beta" mutation L(M212)H that results in incorporation of a BChl molecule, denoted P, in place of the native BPhL. The mutants additionally contain one or two newly introduced aspartic acid residues. In the triple mutant F(L97)V/F(L121)D/L(M212)H, an Asp replaces Phe at L121 (near BPhL), while in the quadruple mutant F(L97)V/F(L121)D/G(M201)D/ L(M212)H aspartic acid residues are introduced at L121 and at M201 (near BChlL). These mutants also incorporate a Val residue at L97 (near BPhL) that is photochemically silent but appears to increase RC protein stability. Femtosecond transient absorption studies reveal a longer P* lifetime in both the triple mutant (10 +/- 2 ps) and quadruple mutant (19 +/- 3 ps) compared to wild-type (4.3 +/-0.3 ps). In the quadruple mutant, P* decay occurs via a combination of electron transfer to the L side to give an intermediate P+I- (involving P+P- and P(+)BChl(L)(-)) in 67% yield, decay to the ground state in 15% yield, and electron transfer to the M side to form P+BPhM- in 18% yield. Kev observations on the quadruple mutant include significant bleaching in the 530-nm Q(x) absorption band of BPhM, and distinctive biexponential decay kinetics in the 600-700-nm anion region with time constants of 200 +/- 30 ps (associated with decay of P+I-) and 1-4 ns (associated with charge recombination of P+BPM-). These findings are evidence for parallel primary charge transfer to the L-side and to the normally inactive M-side. Similar results are obtained for the triple mutant, but the yields of electron transfer to the M side (12%) and P* decay to the ground state (5%) are lower and the yield of electron transfer to the L side correspondingly higher (83%). One of the most interesting differences between the two mutants is that even though the initial yield of electron transfer from P* to the L side is higher in the triple mutant, the yield of the final L-side state P(+)Q(A)(-) is smaller than in the quadruple mutant (38% versus 48%). This distinction derives from differences in the nature of P+I- and the rates of its decay pathways in the two mutants. These and other results are discussed in terms of the effects that the Asp residues appear to have on the free energies of the charge-separated states, namely raising P(+)beta (-) (Asp L121) and P+BChl(L)(-)(Asp M201). The results obtained here complement those on related mutants in providing a consistent picture of the free energies of the states and the primary events in this family of RCs and in the native system. One conclusion is chat P+BCh(L)(-) in wild-type RCs probably lies 80-100 meV below P*, which is a slightly larger free energy gap than previously estimated.