Synthesis and Reactivity of Bis-tris(pyrazolyl)borate Lanthanide/Aluminum Heterobimetallic Trihydride Complexes

Abstract

Molecular heterobimetallic hydride complexes of lanthanide (Ln) and main-group (MG) metals exhibit chemical properties unique from their monometallic counterparts and are highly reactive species, making their synthesis and isolation challenging. Herein, molecular Ln/Al heterobimetallic trihydrides [Ln(Tp) 2 (μ-H) 2 Al(H)(N″)] [2-Ln; Ln = Y, Sm, Dy, Yb; Tp = hydrotris(1-pyrazolyl)borate; N″ = N(SiMe 3 ) 2 ] have been synthesized by facile insertion of aminoalane [Me 3 N•AlH 3 ] into the Ln− N amide bonds of [Ln(Tp) 2 (N″)] (1-Ln). Thus, this is a simple synthetic strategy to access a range of Ln/Al hydrides. Reactivity studies demonstrate that 2-Ln is a heterobimetallic hydride, with evidence for the cooperative nature of 2-Ln shown by the catalytic amine−borane dehydrocoupling under ambient conditions in contrast to its monomeric counterparts. * sı Supporting InformationThe Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.inorgchem.4c00824.Data that support the findings of this study and additional references 22 (PDF)Accession Codes CCDC 2313687−2313695 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk

Activation and functionalisation of carbon dioxide by bis-tris(pyrazolyl)borate-supported divalent samarium and trivalent lanthanide silylamide complexes

“…38 The Ln–N(κ 3 -Tp) bond distances in 3-Ln are consistent with [Ln(Tp) 2 (X)]. 32 The Ln–O(OSiMe 3 ) bond distances in 3-Ln are consistent with heteroleptic monomeric Ln( iii ) silyloxides containing Ln–O(OSiMe 3 ) (Ln = Y, 44,45 Sm) 46 bonds and homoleptic monomeric Ln( iii ) silyloxides [Ln(OSiR 3 ) 3 (LB) x ] (Ln = Y, R = O t Bu, 47 Ph; 48 Sm, R = SiMe 3 , 49 Ph) 50 (see ESI Table 1† for detailed data comparisons). The Sm–N(Tp) bond distances in 3-Sm are shorter than those in 1-Sm(LB) , consistent with the smaller ionic radius of Sm( iii ) vs. Sm( ii ).…”

“…Potassium hydrotris(1-pyrazolyl)borate K(Tp), K(N′′) (N′′ = N(SiMe 3 ) 2 ), Ln(OTf) 3 (OTf = CF 3 SO 3 ; Ln = Y, Sm, Dy), [Ln(Tp) 2 (OTf)] (Ln = Y, Sm, Dy), [Ln(Tp) 2 (N′′)] (Ln = Y, Sm), were synthesised according to published procedures. 32…”

“…2.5–3.0%. 31,32 IR (ATR): 3143 (w, υ sp 2 -CH ), 3116 (w, υ sp 2 -CH ), 2445 (w, υ BH ), 2406 (w, υ BH ), 2372 (w, υ BH ), 1726 (w), 1614 (w), 1505 (m, υ CC ), 1402 (s), 1384 (s), 1293 (s), 1209 (s), 1118 (s), 1045 (s), 973 (s), 925 (w), 876 (w), 803 (w), 752 (s), 722 (s), 668 (s), 620 (s) cm −1 . The multinuclear NMR data below for 1-Sm(THF) was obtained by extracting product into d 8 -toluene from the dried filtrate in THF (after synthesis) and the data were collected within 12 hours.…”

“…17 a ,23,29,30 Reduction of Ln( iii ) [Ln(Tp) 2 (OTf)] (OTf = triflate) was shown as a viable route to access Ln( ii ) [Ln(Tp) 2 ] (Ln = Eu, Yb) complexes. 31 Utilising two small unsubstituted Tp ligands enabled isolation of the reactive Ln( iii ) amide complexes [Ln(Tp) 2 (N′′)], 32 which were inaccessible in the bulky [Ln(Tp*) 2 ] + ligand environment. 33…”

f-Block hydride complexes – synthesis, structure and reactivity

“…113 Similarly, Farnaby and Weetman recently demonstrated the insertion of trihydroaluminium across a {Tp 2 Ln-N′′} bond, yielding a bridged hydride, Tp 2 Ln( μ 2 -H ) 2 Al(H)N′′, with rapidly-exchanging bridging and terminal hydrides. 121 The Anwander group have gone on to expand the scope of Ln⋯H–E complexes, providing examples with E = Ge, Sn and Pb. 114 In NBO calculations based on their data, they found increasing importance of a direct Ln–E interaction upon moving from Pb to Ge, while the Ln–H bond concurrently lengthens.…”