Complexes of the tripodal phosphine ligands PhSi(XPPh$_2$)$_3$ (X = CH$_2$, O): synthesis, structure and catalytic activity in the hydroboration of CO$_2$ - Archive ouverte HAL Access content directly
Journal Articles Dalton Transactions Year : 2016

Complexes of the tripodal phosphine ligands PhSi(XPPh$_2$)$_3$ (X = CH$_2$, O): synthesis, structure and catalytic activity in the hydroboration of CO$_2$

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1

Abstract

The coordination chemistry of Fe$^{2+}$, Co$^{2+}$ and Cu$^+$ ions was explored with the triphosphine and triphosphinite ligands PhSi{CH$_2$PPh$_2$}$_3$ (1) and PhSi{OPPh$_2$}$_3$ (2), so as to evaluate the impact of the electronic properties of the tripodal phosphorus ligands on the structure and reactivity of the corresponding complexes. The synthesis and characterization of the complexes [Fe(κ$^3$-PhSi{CH$_2$PPh$_2$}$_3$)(MeCN)$_3$][OTf]$_2$ (3) (OTf = O$_3$SCF$_3$), [Fe(κ$^3$-PhSi{OPPh$_2$}$_3$)(MeCN)$_3$][OTf]$_2$ (3’), [Co(κ$^2$-PhSi{CH$_2$PPh$_2$}$_3$)Cl$_2$] (4), [Co(κ$^3$ -PhSi {OPPh$_2$}$_3$)Cl$_2$] (4’), [Cu(κ$^3$-PhSi{CH$_2$PPh$_2$}$_3$)Br] (5) and [Cu(κ$^3$-PhSi{OPPh$_2$}$_3$)I] (5’) were carried out. The crystal structures of 3, 3’, 4, 4’, and of the solvates 5·3THF and 5’·THF are reported. Complexes 3–5’ were shown to promote the catalytic hydroboration of CO$_2$ with (9-BBN)$_2$ (9-BBN = 9-borabicyclo [3.3.1]nonane). While the iron and cobalt complexes of the triphosphine 1 are more active than the analogous complexes with 2, the opposite trend is observed with the copper catalysts. Overall, the copper catalysts 5 and 5’ are both more reactive and more selective than the Fe and Co catalysts, enabling the formation of the acetal H$_2$C(OBBN)$_2$ with a high molar ratio of H$_2$ C(OBBN)$_2$:CH$_3$OBBN up to 92 : 8.
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cea-01369401 , version 1 (15-02-2019)

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Alicia Aloisi, Jean-Claude Berthet, Caroline Genre, Pierre Thuéry, Thibault Cantat. Complexes of the tripodal phosphine ligands PhSi(XPPh$_2$)$_3$ (X = CH$_2$, O): synthesis, structure and catalytic activity in the hydroboration of CO$_2$. Dalton Transactions, 2016, 45, pp.14774-14788. ⟨10.1039/c6dt02135b⟩. ⟨cea-01369401⟩
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