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Issue 27, 2015
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(Iminophosphoranyl)(thiophosphoranyl)methane rare-earth borohydride complexes: synthesis, structures and polymerization catalysis

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Abstract

The (iminophosphoranyl)(thiophosphoranyl)methanide {CH(PPh2[double bond, length as m-dash]NSiMe3)(PPh2[double bond, length as m-dash]S)} ligand has been used for the synthesis of divalent and trivalent rare-earth borohydride complexes. The salt metathesis of the potassium reagent [K{CH(PPh2[double bond, length as m-dash]NSiMe3)(PPh2[double bond, length as m-dash]S)}]2 with [Yb(BH4)2(THF)2] resulted in the divalent monoborohydride ytterbium complex [{CH(PPh2[double bond, length as m-dash]NSiMe3)(PPh2[double bond, length as m-dash]S)}Yb(BH4)(THF)2]. The 2D 31P/171Yb HMQC-NMR spectrum clearly showed the coupling between both nuclei. The trivalent bisborohydrides [{CH(PPh2[double bond, length as m-dash]NSiMe3)(PPh2[double bond, length as m-dash]S)}Ln(BH4)2(THF)] (Ln = Y, Sm, Tb, Dy, Er, Yb and Lu) were obtained by reaction of [K{CH(PPh2[double bond, length as m-dash]NSiMe3)(PPh2[double bond, length as m-dash]S)}]2 with [Ln(BH4)3(THF)3]. All new compounds were characterized by single X-ray diffraction. The divalent and trivalent compounds were next used as initiators in the ring-opening polymerization (ROP) of ε-caprolactone (CL) and trimethylene carbonate (TMC). All complexes afforded a generally well-controlled ROP of both of these cyclic esters. High molar mass poly(ε-caprolactone) diols (Mn,NMR < 101 300 g mol−1, ĐM = 1.44), and α,ω-dihydroxy and α-hydroxy,ω-formate telechelic poly(trimethylene carbonate)s (Mn,NMR < 20 000 g mol−1, ĐM = 1.61) were thus synthesized under mild operating conditions.

Graphical abstract: (Iminophosphoranyl)(thiophosphoranyl)methane rare-earth borohydride complexes: synthesis, structures and polymerization catalysis

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Article information


Submitted
30 Dec 2014
Accepted
27 Jan 2015
First published
16 Feb 2015

Dalton Trans., 2015,44, 12338-12348
Article type
Paper

(Iminophosphoranyl)(thiophosphoranyl)methane rare-earth borohydride complexes: synthesis, structures and polymerization catalysis

M. Schmid, P. Oña-Burgos, S. M. Guillaume and P. W. Roesky, Dalton Trans., 2015, 44, 12338
DOI: 10.1039/C4DT04034A

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