Synthesis and structure of 3,5-dimethylpyrazolyl iron and cobalt dinitrosyl dimers

Abstract

. Can. J. Chem. 57,3119(1979).The synthesis and characterization of two 3,5-dimethylpyrazoly1 metal dinitrosyl dimers [(N2CSH7)M(N0)2]2 (where M = Fe or Co) are described and their X-ray crystal structures detailed. Both complexes crystallize in the monoclinic space group C2/c, a = 23.848(2),

The synthesis and structural characterization of linear and macrocyclic bis(dinitrosyliron) complexes supported by bis(phosphine) bridging ligands

“…In turn, the nitrosyl stretching frequencies observed for both 8 and 9 appear at an even lower wavenumber. The macrocyclic DPPM-supported complex, 8, exhibits four distinct IR absorptions (1733, 1721, 1687, and 1668 cm -1 ) in the solid and in solution (spectra obtained from samples dissolved in CH 2 Cl 2 match previously reported values (19)), possibly arising from the interaction of the Fe(NO) 2 centers, as has been observed in other cyclic systems (19,20). This phenomenon appears to depend on ring size, as the related ten-membered ring compound, 9, displays only two nitrosyl stretching signals (1723 and 1679 cm -1 ) in both the solid and liquid states.…”

Neutral and reduced Roussin's red salt ester [Fe2(μ-RS)2(NO)4] (R = n-Pr, t-Bu, 6-methyl-2-pyridyl and 4,6-dimethyl-2-pyrimidyl): synthesis, X-ray crystal structures, spectroscopic, electrochemical and density functional theoretical investigations

“…2.70 Å suggests that there is a fairly strong interaction between the two iron centers. The average Fe–N(NO) bond distance for complex 1–4 is ~1.670 Å, which is significantly longer than the reported value in the dinuclear complex Fe 2 (μ-L) 2 (NO) 4 (L = Ph 2 PCH 2 PPh 2 and Ph 2 PC ≡ CPPh 2 ) (average values: 1.644 and 1.656 Å),16a clearly shorter than the reported value in the dinuclear complex [(N 2 C 5 H 7 )Fe(NO) 2 ] 2 (N 2 C 5 H 7 = 3,5-dimethylpyrazolyl) (average value: 1.696 Å) 19 and the tetramer [Fe(NO) 2 (Im)] 4 (Im = imidazole) (average value: 1.694 Å),16b but only slightly shorter than the value found in the complex Fe(NO) 2 [(SC 6 H 4 - o -NHC(O)CH 3 ) 2 ] − (average value: 1.681 Å) 10e. The Fe–Fe distance and the average Fe–S bond length for complex 4 are 2.741 and 2.278 Å, respectively, which are longer than the corresponding values (2.698, 2.708, 2.708 and 2.257, 2.257, 2.270 Å) for complexes 1–3 , indicating that complex 4 is essentially more unstable.…”

Synthesis, Structures, Spectroscopic and Electrochemical Properties of Dinitrosyl Iron Complexes with Bipyridine, Terpyridine, and 1,10-Phenathroline

“…Each iron center is connected to four nitrogen atoms, which include two from the nitrosyls and two nitrogen atoms from the bipy ligands, with a pseudo-tetrahedral geometry. The average Fe-N( NO ) bond distance of 1.650 Å is similar to those reported in mononuclear complexes Fe(NO) 2 (sparteine) (average value: 1.646 Å),10 [(MeIm) 2 Fe(NO) 2 ] (MeIm = 1-methylimidazole) (average value: 1.649 Å)9a and [(DAD)Fe(NO) 2 ] (DAD = diazadiene) (average value: 1.641 Å), 7d but clearly shorter than those found in the tetranuclear [Fe(NO) 2 (Im-H)] 4 (Im = imidazole) (average value: 1.694 Å)9b and the dinuclear complexes, [(N 2 C 5 H 7 )Fe(NO) 2 ] 2 (N 2 C 5 H 7 = 3,5-dimethylpyrazolyl) (average value: 1.696 Å),22 in which the iron is considered to carry one positive charge in order to balance the negative charge on the nitrogen-contained ligands due to deprotonation. This positive Fe center would have less electrons available for back-donation to the nitrosyl ligands, resulting in weaker Fe-N bonds.…”