The reaction of [Cp(2)ZrCl(2)] with the lithium salt Li[FcBH(3)] in stoichiometric ratios of 1.5 : 1 or 0.4 : 1 furnishes the mixed-metallocene complexes [Cp(2)(Cl)Zr(H(3)BFc)] (1) and [Cp(2)Zr(H(3)BFc)(2)] (3), respectively (Cp = cyclopentadienyl; Fc = ferrocenyl). When the two reagents are combined in a ratio of 0.6 : 1, complex 1 is formed together with the zirconium hydride species [Cp(2)(H)Zr(H(3)BFc)] (2). Compound 2 can be obtained in pure form from [Cp(2)Zr(H)Cl] and Li[FcBH(3)]. Treatment of the half-sandwich complexes [(C(5)R(5))ZrCl(3)] with 3 equivalents of Li[FcBH(3)] leads to the heterotetranuclear aggregates [(C(5)R(5))Zr(H(3)BFc)(3)] (4: R = H; 5: R = CH(3)). Li(2)[fc(BH(3))(2)] and 3 equivalents of [Cp(2)ZrCl(2)] give the heterotrinuclear compound [fc(BH(3)Zr(Cl)Cp(2))(2)] (6) with bridging ferrocenylene core (fc = 1,1'-ferrocenylene). According to X-ray crystallography, the trihydroborate ions are coordinated in a [Zr(μ-H)(2)B(H)-] fashion in 1, 2, 3 and 6, whereas 4 and 5 are carrying tridentate trihydroborate ligands.
N‐methyl‐1, 3‐propylenediaminoboryl ferrocene (1‐H) was obtained by a three‐step synthesis: i) At first ferrocene was reacted with BBr3 to give dibromoboryl ferrocene (FcBBr2). ii) In a second step FcBBr2 was transformed into FcB(OMe)2 by treatment of FcBBr2 with Me3SiOMe. iii) Finally reaction of FcB(OMe)2 with H2NCH2CH2CH2NMeH 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 Me2SO4. The metalated ferrocene derivative (Li2(THP)2Mg3(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 Li2(THP)2Mg3(TMP)2[3]2 were available by gas‐phase diffusion of hexane into a concentrated THP solution at ambient temperature (space group C2/c). The crystal structure of Li2(THP)2Mg3(TMP)2[3]2 displays a racemic dimer of the Rp‐ and the Sp‐enantiomer.
The title compound, [FeZr2(C5H5)4Cl2(C13H18B2)], is a heteronuclear complex that consists of a [3]ferrocenophane moiety substituted at each cyclopentadienyl (Cp) ring by a BH3 group; the BH3 group is bonded via two H atoms to the Zr atom of the zirconocene chloride moiety in a bidentate fashion. The two Cp rings of the [3]ferrocenophane moiety are aligned at a dihedral angle of 8.9 (4)° arising from the strain of the propane-1,3-diyl bridge linking the two Cp rings. [One methylene group is disordered over two positions with a site-occupation factor of 0.552 (18) for the major occupied site.] The dihedral angles between the Cp rings at the two Zr atoms are 50.0 (3) and 51.7 (3)°. The bonding Zr⋯H distances are in the range 1.89 (7)–2.14 (7) Å. As the two Cp rings of the ferrocene unit are connected by an ansa bridge, the two Zr atoms approach each other at 6.485 (1) Å. The crystal packing features C—H⋯Cl interactions.
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