201164-12-7

Upstream product

• 908093-98-1 diazodiphenylmethane 

Downstream Products

• 201164-13-8 Fe(dibenzotetramethyltetra[14]azaannulenide)(C=CPh₂) * toluene 

Relevant academic research and scientific papers

The metal-carbon multiple bond in iron(I)- and iron(II)-dibenzotetramethyltetra[14]azaannulene: Carbene, carbonyl, and isocyanide derivatives

The two parent compounds used for studying the iron-carbon multiple bond interactions are [Fe(tmtaa)] (1), and [Fe(tmtaa)Na(THF)3] (2) [tmtaadibenzotetramethyltetraaza[14]annulene dianion], the latter being obtained by reduction of 1. The reaction of 1 with CO led to the corresponding monocarbonyl derivative [Fe(tmtaa)(CO)(L)] [L=THF, 3; L=Py, 4], while the reaction with RNC allowed us to isolate mono-isocyanide [Fe(tmtaa)(o-Me3Si-C6H4NC)(THF)] (5), [Fe(tmtaa)(nBuNC)(THF)] (6), and bis-isocyanide [Fe(tmtaa)(tBuNC)2] (7) derivatives. Reduction of 6 with sodium metal or the reaction of 1 with NaCN led to a monocyano derivative bridged into a dimeric form by sodium cations in [{Fe(tmtaa)(CN)}2(μ-NaLn)2] [L=THF, n=3, 8a; L=DME, n=2, 8b], while the reaction of 1 with nBu4N+CN- led to the monomeric form [Fe(tmtaa)(CN)]-(nBu4N)+ (9). A detailed magnetic analysis of 1-10, the last one being the bis-pyridine derivative [Fe(tmtaa)(Py)2] (10) showed a variety of low and intermediate spin states, and spin crossovers (with a minor role played by high spin states) as a function of the axial ligands. A remarkable difference was observed with the analogous porphyrin derivatives. The d7 iron(I) derivative 2 occurs in tight ion-pair form, both iron and sodium being bonded to the tmtaa ligand. The reaction of 2 with carbon monoxide led to a monocarbonyl derivative bridged in a dimeric form by sodium cations bonded to the oxygen atoms in [{Fe(tmtaa)}2{μ-CONa(THF)2}2] (11). Both 2 and 11 showed a spin conversion between S=1/2 and S=3/2, with a small antiferromagnetic coupling in the latter case, due to the dimeric form. The reaction of 1 with diazoalkane RR′CN2 led to the corresponding low-spin diamagnetic carbene derivatives [Fe(tmtaa)(CRR′)] [R=R′=Ph, 12; R=Ph, R′=H, 13], the first one being by far more thermally stable, while the second one decomposes at room temperature to 1 and a mixture of cis and trans-stilbene. Both react with O2 giving Ph2CO and PhCHO and the μ-oxo dimer [{Fe(tmtaa)}(μ-O)] (14). The proposed structures are supported by the X-ray analyses on complexes 2, 8b, 9, 11b and 12.

Iron-carbene functionalities supported by a macrocyclic ligand: Iron-carbon double bond stabilized by tetramethyldibenzotetraazaannulene

We report an unprecedented entry to the chemistry of the iron-carbene functionality supported by an easily available macrocycle.