In:
Dalton Transactions, Royal Society of Chemistry (RSC), Vol. 52, No. 22 ( 2023), p. 7635-7645
Abstract:
We report the synthesis and characterisation of a series of M( iv ) substituted cyclopentadienyl hypersilanide complexes of the general formula [M(Cp R ) 2 {Si(SiMe 3 ) 3 }(X)] (M = Hf, Th; Cp R = Cp′, {C 5 H 4 (SiMe 3 )} or Cp′′, {C 5 H 3 (SiMe 3 ) 2 -1,3}; X = Cl, C 3 H 5 ). The separate salt metathesis reactions of [M(Cp R ) 2 (Cl) 2 ] (M = Zr or Hf, Cp R = Cp′; M = Hf or Th, Cp R = Cp′′) with equimolar K{Si(SiMe 3 ) 3 } gave the respective mono-silanide complexes [M(Cp′) 2 {Si(SiMe 3 ) 3 }(Cl)] (M = Zr, 1; Hf, 2), [Hf(Cp′′)(Cp′){Si(SiMe 3 ) 3 }(Cl)] (3) and [Th(Cp′′) 2 {Si(SiMe 3 ) 3 }(Cl)] (4), with only a trace amount of 3 presumably formed via silatropic and sigmatropic shifts; the synthesis of 1 from [Zr(Cp′) 2 (Cl) 2 ] and Li{Si(SiMe 3 ) 3 } has been reported previously. The salt elimination reaction of 2 with one equivalent of allylmagnesium chloride gave [Hf(Cp′) 2 {Si(SiMe 3 ) 3 }(η 3 -C 3 H 5 )] (5), whilst the corresponding reaction of 2 with equimolar benzyl potassium yielded [Hf(Cp′) 2 (CH 2 Ph) 2 ] (6) together with a mixture of other products, with elimination of both KCl and K{Si(SiMe 3 ) 3 }. Attempts to prepare isolated [M(Cp R ) 2 {Si(SiMe 3 ) 3 }] + cations from 4 or 5 by standard abstraction methodologies were unsuccessful. The reduction of 4 with KC 8 gave the known Th( iii ) complex, [Th(Cp′′) 3 ]. Complexes 2–6 were characterised by single crystal XRD, whilst 2, 4 and 5 were additionally characterised by 1 H, 13 C{ 1 H} and 29 Si{ 1 H} NMR spectroscopy, ATR-IR spectroscopy and elemental analysis. In order to probe differences in M( iv )–Si bonds for d- and f-block metals we studied the electronic structures of 1–5 by density functional theory calculations, showing M–Si bonds of similar covalency for Zr( iv ) and Hf( iv ), and less covalent M–Si bonds for Th( iv ).
Type of Medium:
Online Resource
ISSN:
1477-9226
,
1477-9234
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2023
detail.hit.zdb_id:
1472887-4
Bookmarklink