Magnesiation of N ‐Methyl‐1, 3‐propylenediaminoboryl Ferrocene

N ‐methyl‐1, 3‐propylenediaminoboryl ferrocene ( 1 ‐H) was obtained by a three‐step synthesis: i) At first ferrocene was reacted with BBr 3 to give dibromoboryl ferrocene (FcBBr 2 ). ii) In a second step FcBBr 2 was transformed into FcB(OMe) 2 by treatment of FcBBr 2 with Me 3 SiOMe. iii) Finally reaction of FcB(OMe) 2 with H 2 NCH 2 CH 2 CH 2 NMeH yielded the boryl ferrocene 1 ‐H. In addition we examined the metalation of 1 ‐H with magnesium 2, 2, 6, 6‐tetramethylpiperidide (TMP) and mixtures of Li(TMP)/Mg(TMP) 2 . The reaction of 1 ‐H with 0.5 equivalent of Mg(TMP) 2 yielded quantitatively the homoleptic complex Mg[ 1 ] 2 whereas metalation of 1 ‐H with 1.5 and 2 equivalents of Mg(TMP) 2 gave product mixtures. However, N , N '‐dimethyl‐1, 3‐propylenediaminoboryl ferrocene ( 1 ‐Me) and the ortho‐ methylated derivatives 2 ‐Me and 3 ‐Me ( 3 ‐Me bears additionally one Me group in 1′‐postion) could be identified after derivatization with Me 2 SO 4 . The metalated ferrocene derivative (Li 2 (THP) 2 Mg 3 (TMP) 2 [ 3 ] 2 ) which is bearing one Li and one Mg atom in the ortho ‐position and a further two Mg atoms in N ‐ and 1′‐positions, was formed in good yield by treatment of 1 ‐H with an excess of a 1:2 mixture of Li(TMP) and Mg(TMP) 2 in tetrahydropyran (THP). Single crystals of the racemic complex Li 2 (THP) 2 Mg 3 (TMP) 2 [ 3 ] 2 were available by gas‐phase diffusion of hexane into a concentrated THP solution at ambient temperature (space group C 2/ c ). The crystal structure of Li 2 (THP) 2 Mg 3 (TMP) 2 [ 3 ] 2 displays a racemic dimer of the R p ‐ and the S p ‐enantiomer.