A new family of chiral chelating diamines with transition-metal stereocenters:: Synthesis, structure, and reactivity of the enantiomerically pure dirhenium-substituted 1,2-diamine (η5-C5H5)Re(NO)(PPh3) (CH2N(CH3)CH2CH2(H3C)NCH2)(Ph3P)(ON)Re(η5-C5H5)

Reaction of enantiopure (S)-(eta (5)-C5H5)Re(NO)(PPh3)(CH3) ((S)-1) with Ph3C(+)BF(4)(-)(1 equiv) and then the N,N ' -dimethyl 1,2-diamine HN(CH3)CH2CH2(H3C)NH (0.5 equiv) gives the diammonium salt (SReSRe)-[(eta (5)-C5H5)Re(NO)(PPh3)(CH2NH(CH3)CH2CH2(H3C)HNCH2)(Ph3P)(ON)Re(eta (5)-C5H5)](2+)(BF4- (94%) as a mixture of Re/N configurational diastereomers. Reaction with t-BuOK yields the title compound (SReSRe)-4 (66%) as an air-stable orange powder. Reaction with (PhCN)(2)PdCl2 gives a single diastereomer of a chelate complex, (SReRNRNSRe)-[(eta (5)-C5H5)Re(NO)(PPh3)-(CH2N(CH3)CH2CH2(H3C)NCH2)(Ph3P)(ON)Re(eta (5)-C5H5)]PdCl2 (80%), the configuration and approximate Ca symmetry of which has been established crystallographically. Racemic 1, Ph3C+BF4- (1 equiv), and the N,N ' -dimethyl 1,2-diamine HN(CH2CH3)CH2CH2(H3CCH2)NH (1 equiv) give [(eta (5)-C5H5)Re(NO)(PPh3)(CH2NH(CH2CH3)CH2CH2NH(CH2CH3))]+BF4-, and the crystal structure of the SReSN,RReRN diastereomer is determined. The ReCH2N conformations of the preceding compounds, and their influence upon the diastereoselectivities, are analyzed in detail.