Synthesis and complexes of new selenoether macrocycles

Abstract

The first known examples of alkyl Pt(II) complexes with macrocyclic selenoethers [PtMe2L] (L = [8]aneSe2 and [16]aneSe4) have been synthesised and characterised as part of a series of dimethyl Pt(II) complexes with selenoether ligands (L = MeSe(CH2)nSeMe, n = 2, 3; o-C6H4(CH2SeMe)2). A new series of [PtMe3I(?2-L-L)] complexes has been synthesised and characterised, which includes the first examples of this type with macrocyclic selenoethers (L-L = o-C6H4(CH2EMe)2, E = Se, Te; MeC(CH2SeMe)3; [8]aneSe2 and [16]aneSe4). The first bridging ditelluroether trimethyliodo Pt(IV) complex, [(PtMe3I)2(MeTeCH2TeMe)] has also been characterised. [PtMe3(?3-[16]aneSe4)]PF6 was isolated and characterised, which is the first cationic trialkylplatinum(IV) complex with a macrocyclic selenoether ligand, and an unusual example of ?3-[16]aneSe4 coordination.

Five novel macrocycles containing a mixed O/Se donor set of the type OxSe2x, two small ring Se3 macrocycles and two Se2N macrocycles have been synthesised. Two methods of production have been investigated from the same precursors, a NaBH4 reduction and a low temperature Na/NH3 (l) reduction, demonstrating that reaction conditions are very important for determining preferred ring size and yields. The Se3 and Se2N macrocycles have been synthesised in multigram quantities, and crystal structures of two of these macrocycles have been obtained.

The first examples of complexes with tridentate homoleptic selenoether macrocycles and tridentate Se2N macrocycles have been prepared and characterised. Platinum(II) dichloride complexes were prepared for L6-L9, but proved to be extremely poorly soluble. No evidence of platinum(II) complexation with methyl co-ligands was observed. Reaction of [PtMe3I] with L6-L10 resulted in the production of fac-coordinated, cationic Pt(IV) complexes of the type [PtMe3L]I. This geometry is confirmed by two crystal structures, of [PtMe3(L6)]I and [PtMe3(L9)]I. Cr(III) complexes of the type [CrCl3L] have been produced and characterised for L1, L6-10, and are generally hydrolytically sensitive, insoluble solids.

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ORCID for Gillian Reid: orcid.org/0000-0001-5349-3468

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