Mono and bis carbene neodymium(III) spirocyclic complexes with a cumulene carbon metal structure

In this study, we performed the first step reaction of [Li2C(Ph2P = NSiMe3)2] (1) with NdCl3 in 1:1 M ratio in situ, with subsequent addition of second molar ratio of 1 to the reaction solution to generate bis carbene neodymium organometallic compound of [Nd{C(Ph2P = NSiMe3)2}2][Li(THF)n] (2). The anion of this isolated compound 2 formed a rare linear carbene metal cumulene structure (C=Nd = C) demonstrated by crystal structure determination. In order to synthesize a mono carbene neodymium compound with bis(diphenyliminophosphorane)methandiide (1) to compare its bonding feature to the reactions of [Li2C(Ph2P = NSiMe3)2] (1) with NdCl3 and CpTl in THF, eventually crystal structure analysis showed that generated another neodymium organometallic complexes of [Cp2Nd{CH(Ph2P = NSi–Me3)2}2] (3), unexpected the methandiide carbon of PCP ligand was protonated. Furthermore, DFT calculations demonstrated the presence of multiple bonding interaction in the carbon metal cumulene structure (C=Nd = C). NBO analysis revealed that the average overall C=Nd double bond contains 21.19% carbon and 14.43% Nd component respectively, indicating it is a covalent conjugated multiple bonding system. To the best of our knowledge, it is the first structural example of PCP carbene neodymium compound with the cumulene structure (C=Nd = C) unit.Graphical abstract

Source: Journal of Organometallic Chemistry - May 21, 2019 Category: Chemistry Source Type: research