Recent developments in transition metal diaryl chemistry

Abstract

This Perspective discusses the synthesis and reactivity of low-coordinate transition metal diaryl complexes. The development of sterically demanding ligands, in particular m-terphenyls is facilitating the isolation of complexes featuring two-coordinate open-shell transition metal centres. These coordinatively unsaturated complexes are now being investigated for their reaction chemistry, which is not only contributing to the elucidation of the structure and bonding within these systems but is also leading to the formation of novel compounds.

Measurement of Extreme Hyperfine Fields in Two-Coordinate High-Spin Fe2+ Complexes by Mössbauer Spectroscopy: Essentially Free-Ion Magnetism in the Solid State

“…Heat-capacity measurements in an external magnetic field of up to 5 T were carried out for complex 3 using the Quantum Design physical property measurement system (PPMS 6000) at Osaka University. The compounds Fe{N(SiMe 3 )(Dipp)} 2 (1), 1,9,12 Fe(OAr′) 2 (2), 12,15 and Fe{C(SiMe 3 ) 3 } 2 (3) 17,18 were prepared according to literature procedures.…”

“…This technique can provide highly useful information on the bonding, as well as the electronic and magnetic properties, including the internal magnetic fields in the complexes. Herein, we report Mossbauer measurements to characterize the magnetic properties of the set of two-coordinate Fe(II) complexes Fe{N(SiMe 3 )(Dipp)} 2 (1) (Dipp = C 6 H 3 -2,6-i Pr 2 ), 1,9,12 Fe(OAr′) 2 (2) [Ar′ = C 6 H 3 -2,6-(C 6 H 3 -2,6-i Pr 2 ) 2 ], 15 and Fe{C(SiMe 3 ) 3 } 2 (3) (Figure 2). 4,17,18 In addition, although neither 1, 2, nor 3 displays EPR signals, we show that heat-capacity measurements on 3 establish that it has a g eff value near 12, consistent with the principal component of the electric field gradient lying along the z axis.…”

Solventless Synthesis of Quaterphenyls and Terphenyls from Chalcones and Allylsulfones under Phase Transfer Catalysis Conditions

“…Moreover, meta-terphenyls have been used as ligands [10], as intermediates for the synthesis of covalent nanostructures [11] and as electron transporting material [12]. For example, 5′,5′′′′-sulfonyl-di-[1,1′:3′,1′′]-terphenyl (BTPS, Scheme 1), bearing two meta-terphenyl subunits, has been recently prepared from bis (3,5-dichlorophenyl)sulfone [13] by Suzuki-Miyaura coupling in order to develop new highly efficient organic light emitting diodes (OLED) [14].…”

Synthesis and Magnetic Properties of Linear Two-coordinate Monomeric Diaryliron(II) Complexes Bearing Fused-ring Bulky “Rind” Groups

“…Subsequently, in 2013, the anionic dialkyliron(I) complex, [K(crypt-222) In contrast, a linear two-coordinate iron diaryl compound has not been researched and remains elusive. 5 Although several homoleptic two-coordinate diaryliron(II) complexes, Fe(Ar) 2 , have been successfully isolated using sterically-encumbered aryl groups (Ar = C 6 H 2 -2,4,6-t Bu 3 , 6 C 6 H 3 -2,6-(C 6 H 2 -2,4,6-Me 3 ) 2 , 7 and C 6 H 3 -2,6-(C 6 H 3 -2,6-i Pr 2 ) 2 8 ), their effective magnetic moments (® eff = 4.825.18 ® B ) were similar to the spin-only value (spin-only behavior of an S = 2 corresponds ® eff = 4.90 ® B ), most likely due to the bent geometries at the Fe center [CFe C = 150.34(6)171.1(1)°]. Based on these studies, the metal coordination geometry is responsible for the main magnetic properties of the two-coordinate iron complexes.…”