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 Sept. 2015
Accepted
22 Sept. 2015
First published
22 Sept. 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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