Issue 12, 2015

Two-coordinate group 14 element(ii) hydrides as reagents for the facile, and sometimes reversible, hydrogermylation/hydrostannylation of unactivated alkenes and alkynes

Abstract

Reactions of the solution stable, two-coordinate hydrido-tetrylenes, :E(H)(L) (E = Ge or Sn; L = –N(Ar)(SiPri3); Ar = C6H2{C(H)Ph2}2Pri-2,6,4), with a variety of unactivated cyclic and acyclic alkenes, and one internal alkyne, lead to the rapid and regiospecific hydrometallation of the unsaturated substrate at ambient temperature. The products of the reactions, [LE(C2H4R)] (E = Ge or Sn, R = H, Ph or But), [LE{CH(CH2)3(CH2)n}] (E = Ge, n = 1, 2 or 3; E = Sn, n = 1) and [LE{C(Ph)[double bond, length as m-dash]C(H)(Me)}], include the first structurally characterised examples of two-coordinate amido/alkyl germylenes and stannylenes. The cycloalkene hydrometallation reactions are cleanly reversible under ambient conditions, a process which computational and experimental van't Hoff analyses suggest proceeds via β-hydride elimination from the metal coordinated cycloalkyl ligand. Similarly, the reactions of :Ge(H)(L) with 1,5-cyclooctadiene and 2-methyl-2-butene, both likely proceed via β-hydride elimination processes, leading to the clean isomerisation of the alkene involved, and its subsequent hydrogermylation, to give [LGe(2-cyclooctenyl)] and [LGe{C2H4C(H)Me2}], respectively. Reactions of [LGeEt] and [LGe(C5H9)] with the protic reagents, HCl, NH3 and EtOH, lead to oxidative addition to the germanium(II) centre, and formation of the stable chiral germanium(IV) complexes, [LGe(C5H9)(H)Cl] and [LGe(Et)(H)R] (R = NH2 or OEt). In contrast, related reactions between [LSnEt] and ButOH or TEMPOH (TEMP = 2,2,6,6-tetramethylpiperidinyl) proceed via ethane elimination, affording the tin(II) products, [LSnR] (R = OBut or OTEMP). In addition, the oxidation of [LGe(C6H11)] and [LSn(C2H4But)] with O2 yields the oxo-bridged metal(IV) dimers, [{L(C6H11)Ge(μ-O)}2] and [{L(ButC2H4)Sn(μ-O)}2], respectively.

Graphical abstract: Two-coordinate group 14 element(ii) hydrides as reagents for the facile, and sometimes reversible, hydrogermylation/hydrostannylation of unactivated alkenes and alkynes

Supplementary files

Article information

Article type
Edge Article
Submitted
08 9 2015
Accepted
22 9 2015
First published
22 9 2015
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2015,6, 7249-7257

Two-coordinate group 14 element(II) hydrides as reagents for the facile, and sometimes reversible, hydrogermylation/hydrostannylation of unactivated alkenes and alkynes

T. J. Hadlington, M. Hermann, G. Frenking and C. Jones, Chem. Sci., 2015, 6, 7249 DOI: 10.1039/C5SC03376D

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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