Electrophile Recruitment as a Structural Element in Bis‐Pyrazolate Pyridine Complex Aggregation

Abstract

Redox inert cations are increasingly featuring participating in non-innocent structural aggregation roles. The six-coordinate bis-pyrazolate pyridine pincer (L) complex LFe II (DMAP) 3 (DMAP = 4-dimethylaminopyridine) is oxidized, to Fe III , by excess silver triflate. All beta nitrogen atoms of the pyrazolate rings bind Ag + , to create a species with two linear N-Ag-N units parallel to the linear Fe-O-Fe unit, in [LFe(DMAP) 2 Ag] 2 O 2+ . Excess silver triflate oxidizes LCo II (PEt 3 ) 2 to form CoL 2 Ag 4 (OTf ) 2 -(PEt 3 ) 2 + as its triflate salt, and this has a bis-pincer Co III center where two pyrazolate nitrogen atoms carry Ag(PEt 3 ) + groups and the other two carry AgOTf groups. Finally, deprotonation [a]

Recent Developments in Reactions and Catalysis of Protic Pyrazole Complexes

“…The 4-dimethylaminopyridine (DMAP) complex 26 is paramagnetic, while the isocyanide complex 27 as well as the diphosphine complex 28 obtained similarly is diamagnetic. The DMAP complex 26 is further converted to the oxido-bridged Fe(III) 2 complex 29 upon treatment with silver triflate, although the oxidant remains unclear [54]. In 29, the Lewis-basic pyrazolate arms are bridged by the silver cation.…”

“…This complex catalyzes oxidation of PEt 3 and PPh 3 with nitrous oxide or O 2 , owing to the interconversion between 31 and 32. Meanwhile, the ligand basicity of 31 was suggested by the formation of the cobalt(III) complex 33 with each pyrazolato arm binding to a silver center [54]. Even cooperation of Lewis acid-Brønsted base centers is proposed for the oxidation of 31 in dichloromethane to give the cobalt(III) chlorido complex 34 (Scheme 11) [56].…”

“…Even cooperation of Lewis acid-Brønsted base centers is proposed for the oxidation of 31 in dichloromethane to give the cobalt(III) chlorido complex 34 (Scheme 11) [56]. Synthesis of the elusive, coligand-free bis(pyrazolato) complexes M R L has b achieved for chromium(II) by redox-neutral, salt metathesis reaction of K2 tBu L [54] CrCl2 or treatment of a chromium(II) silylamide and tBu LH2 [57]. The primary product claimed to be the bis(pyrazolato)-type dimer 35, which subsequently converts into th tramer 36 during recrystallization (Scheme 12).…”

“…The primary product claimed to be the bis(pyrazolato)-type dimer 35, which subsequently converts into th tramer 36 during recrystallization (Scheme 12). Owing to the coordinative unsatura 35 reacts with four equiv of DMAP to give the mononuclear bis(dmap) complex 37 w Synthesis of the elusive, coligand-free bis(pyrazolato) complexes M R L has been achieved for chromium(II) by redox-neutral, salt metathesis reaction of K 2 tBu L [54] with CrCl 2 or treatment of a chromium(II) silylamide and tBu LH 2 [57]. The primary product was claimed to be the bis(pyrazolato)-type dimer 35, which subsequently converts into the tetramer 36 during recrystallization (Scheme 12).…”

Bis(2,6-pyrazolyl)pyridines as a New Scaffold for Coordination Polymers

“…For isomeric 3-bpp, there are only a few examples of heteroleptic 1D-CPs [32,33,37,39] of 5,5 -di-substituted 3-bpp and one, of a homoleptic 1D-CP {[Ag 2 (H 2 L) 2 ](NO 3 ) 2 •H 2 O} n with silver(I) ion [40] tetracoordinated by two of the same 3-bpp. Unsubstituted NH groups in this ligand are prone to deprotonation in the presence of a base [41], thereby creating an additional coordination site for an SCO-active metal ion [42], which dramatically changes the topology and the SCO activity of the resulting CPs or MOFs.…”