Synthesis and X-ray structure of a borohydrido metallocene of neodymium and its use as pre-catalyst in Nd/Mg dual-component ethylene and isoprene polymerisations

Abstract

Cp* 2 Nd(BH 4 )(THF) (1) (Cp* = C 5 Me 5 ) has been readily obtained in one step from Nd(BH 4 ) 3 (THF) 3 and fully characterized by 1 H NMR, IR spectroscopy, and elemental analysis. Its X-Ray structure displays a neutral monomeric complex, bearing one slightly distorted terminal BH 4group. Associated to nBuEtMg, 1 affords a highly active catalyst for ethylene polymerisation, the first one prepared from a borohydrido organolanthanide pre-catalyst. In the same experimental conditions, the catalytic behaviour of 1 is similar to that of previously described Cp* 2 NdCl 2 Li(Et 2 O) 2 (2). The 1/nBuEtMg system is not deactivated even in the presence of large excesses of THF. In contrast to its chloro homologue 2, the addition of 1 equivalent of nBuEtMg to 1 affords a catalyst for a trans-selective polymerisation of isoprene.2

Structural diversity in the borohydrido lanthanides series: First isolation and X-ray crystal structure of ionic

“…A few precedent structures of this type have been reported in the lanthanides series [18][19][20][21][22]. The Sm-B distances in the cation (2.59(6) and 2.61(3) Å ) and in the anion (2.58(6) and 2.58(2) Å ) of 1, as well as IR data, are compatible with a tridentate Sm-ðg 3 -HÞ 3 B-H mode of bonding, likely distorted however, as already observed [23,24]. A borohydride anionic compound of trivalent uranium, showing very similar distances and angles, was also described.…”

Bis(phosphinimino)methanide Borohydride Complexes of the Rare‐Earth Elements as Initiators for the Ring‐Opening Polymerization of ε‐Caprolactone: Combined Experimental and Computational Investigations

“…[21] In the 1980s Mirsaidov and co-workers developed a more convenient approach starting from LnCl 3 (Ln = La, Ce, Pr, Nd, Sm) and NaBH 4 . [22][23][24] Later on, greater value was given to these original species in the promotion of rare-earth borohydride organometallic chemistry [25][26][27][28] and in their use as efficient catalysts for the (co)polymerization of ethylene, [29][30][31] isoprene, [31][32][33][34][35] styrene, [34,36] and some polar monomers such as lactide, [37][38][39][40][41][42] e-caprolactone, [37][38][39][43][44][45][46][47][48][49][50][51][52] trimethylene carbonate, [52] and methyl methacrylate. [53][54][55][56][57] Also, some rare-earthmetal borohydride derivatives such as metallocenes, [31,46] mono-cyclopentadienyl complexes, …”

Lanthanide borohydrido complexes for MMA polymerization: syndio‐ vs iso‐ stereocontrol

“…the presence of a MgR 2 co-catalyst was necessary to enable isoprene 10 or ethylene 11 polymerisation.…”