C–C Activation in the Solid State in an Organometallic σ-Complex

Abstract

Herein is reported the synthesis, by a solid-state reaction from [Ir(NBD)(2)(P(i)Pr(3))][BAr(F)(4)], of the first example of a C-C σ-complex with iridium, [Ir(BINOR-S)(P(i)Pr(3))][BAr(F)(4)]. This compound is unique in that in the solid state it undergoes reversible activation of the C-C single bond that interacts with the metal center, establishing a temperature-dependent equilibrium between Ir(III) C-C σ/Ir(V) bis-alkyl complexes. This process has been interrogated by variable-temperature X-ray diffraction, NMR spectroscopy, and DFT calculations.

A Structurally Characterized Cobalt(I) σ‐Alkane Complex

“…[22] For [Co(L2)-NBD][BAr F 4 ], hydrogenation in FC 6 H 5 solution results in decomposition to a mixture of products. However, as we, [12,26] and others, [27] F 4 ] is so reactive that even at À173 8C data acquisition times longer than 2 h resulted in steady decomposition, loss of diffraction, and a color change of the crystal from brown to blue (i.e., Co II ), which we suggest is due to reaction with adventitious oxygen in the mounting oil.…”

“…For [Co( L2 )‐NBD][BAr F 4 ], hydrogenation in FC 6 H 5 solution results in decomposition to a mixture of products. However, as we, and others, have previously reported, organometallic synthesis in the solid state can promote desirable changes in selectivity when compared to solution routes. This is the case for [Co( L2 )‐NBD][BAr F 4 ].…”

Unsupported boron–carbon σ-coordination to platinum as an isolable snapshot of σ-bond activation

“…A number of σ-alkane complexes have been characterized at low temperature by NMR, but the only structurally characterized examples are topics of debate 8,9 . Isolable σ-complexes range from complexes with weak agostic (that is, supported by a stronger secondary point of ligation) C-H 10,11 , C-C 12,13 and Si-Si 14,15 ligation to strong, unsupported σ-dihydrogen 1,2 and σ-borane complexes [16][17][18][19][20][21][22][23] , whose stability (significantly enhanced in the latter by retrodonation interaction III, Fig. 1a) has led to advances in our understanding of catalytic hydrogenation, hydroboration [24][25][26] , and reversible hydrogen storage by amine-boranes [27][28][29] .…”

Anorganische Chemie 2011

“…Der Komplex [Ir(BINOR‐S) (PiPr3)]BArF4 bildet im Festkörper ein reversibles Gleichgewicht zwischen einem C‐C‐ρ‐IrIII‐Komplex und einem Bis(alkyl)‐IrV‐Komplex (Abbildung 20) 2_35. Letzterer Komplex entsteht bei der oxidativen Addition der C‐C‐Bindung des ρ‐IrIII‐Komplexes an das Iridiumatom.…”