Diastereomerically pure 1-[1-(1,2-dicarba-closo-dodecaboran(12)yl)chlorophosphanyl]-2-N,N-dimethylaminomethylferrocene ((RP,SFc/SP,RFc)-3) and enantiomerically pure (S)-N,N-dimethyl-1-{(R)-2-[(S)-{1-(1,2-dicarba-closo-dodecaboran(12)yl)}chlorophosphanyl]ferrocenyl}ethylamine ((SC,SP,RFc)-4) were prepared by reaction of monolithiated 1,2-dicarba-closo-dodecaborane(12) and the corresponding racemic or enantiomerically pure aminoalkylferrocenyldichlorophosphanes (1 or (S,R)-2). Two equivalents of 1 also reacted with dilithiated 1,2-dicarba-closo-dodecaborane(12) to yield stereoselectively the RP,RP‘,SFc,SFc‘/SP,SP‘,RFc,RFc‘ diastereomer of 1,2-bis[chloro(2-N,N-dimethylaminomethylferrocenyl)phosphanyl]-1,2-dicarba-closo-dodecaborane(12) ((RP,RP‘,SFc,SFc‘/SP,SP‘,RFc,RFc‘)-5). Chlorophosphane (RP,SFc/SP,RFc)-3 was treated with LiAlH4 to afford diastereoselectively the secondary phosphane 1-[1-(1,2-dicarba-closo-dodecaboran(12)yl)phosphanyl]-2-N,N-dimethylaminomethylferrocene ((RP,RFc/SP,SFc)-6) with inverted stereochemistry at the phosphorus center, which in this case was found to slowly undergo epimerization in solution. The chloro groups of (RP,SFc/SP,RFc)-3 and (SC,SP,RFc)-4 were also substituted by various alkoxides to give a series of diastereomerically and enantiomerically pure carbaboranylferrocenyl phosphinites ((RP,RFc/SP,SFc)-7, (RP,RFc/SP,SFc)-8, (RP,RFc/SP,SFc)-9, (SC,RP,RFc)-10, and (SC,RP,RFc)-11). The substitutions occurred with 100% stereoselective inversion of the configurations of the phosphorus centers. The phosphinites display high stability toward oxidation and epimerization. All new compounds were structurally characterized to verify the configurations of the stereogenic centers. The monophosphanyl-substituted carbaboranes exhibit intramolecular hydrogen-bonding interactions between the dimethylamino group and the proton of the second cluster carbon atom.