Anka Pejović

The palladium(II) complex of N,N-diethyl-1-ferrocenyl-3-thiabutanamine: synthesis, solution and solid state structure and catalytic activity in Suzuki–Miyaura reaction

In this paper we wish to present the first results on the synthesis of N,N-diethyl-1-ferrocenyl-3-thiabutanamine, its coordination with palladium(II), the complete characterization of the thus obtained complex (including single crystal X-ray analysis for the complex in two polymorphic forms) and screening of its catalytic activity in Suzuki–Miyaura coupling of phenylboronic acid with several aryl bromides. The complex, either purified and then added to the reaction mixture or generated in situ, proved to be an excellent precatalyst in Suzuki–Miyaura coupling. The chemical behavior of the complex in solution was assessed by detailed NMR analyses and cyclic voltammetry measurements which allowed us to draw a number of mechanistic conclusions.

A new polymorph of 1-ferrocenyl-3-(3-nitroanilino)propan-1-one.

Recrystallization of the title compound, [Fe(C(5)H(5))(C(14)H(13)N(2)O(3))], from a mixture of n-hexane and dichloromethane gave the new polymorph, denoted (I), which crystallizes in the same space group (P1) as the previously reported structure, denoted (II). The Fe-C distances in (I) range from 2.015 (3) to 2.048 (2) Å and the average value of the C-C bond lengths in the two cyclopentadienyl (Cp) rings is 1.403 (13) Å. As indicated by the smallest C-Cg1-Cg2-C torsion angle of 1.4° (Cg1 and Cg2 are the centroids of the two Cp rings), the orientation of the Cp rings in (I) is more eclipsed than in the case of (II), for which the value was 15.3°. Despite the pronounced conformational similarity between (I) and (II), the formation of self-complementary N-H···O hydrogen-bonded dimers represents the only structural motif common to the two polymorphs. In the extended structure, molecules of (I) utilize C-H···O hydrogen bonds and, unlike (II), an extensive set of intermolecular C-H···π interactions. Fingerprint plots based on Hirshfeld surfaces are used to compare the packing of the two polymorphs.

Synthesis of ferrocene-containing six-membered cyclic ureas via α-ferrocenyl carbocations

A series of ferrocene-containing six-membered cyclic ureas (1-aryl-4-ferrocenyl-3-phenyltetrahydropyrimidin-2(1H)-ones) was synthesized (in high-to-excellent yields) by reacting the corresponding aminopropanols with phenyl isocyanate and the subsequent intramolecular cyclization of the thus obtained β-hydroxy ureas (prompted by acetic acid), via an α-ferrocenyl carbocation.

1-Ferrocenyl-3-(3-fluoro-anilino)propan-1-one.

The title ferrocene derivative, [Fe(C5H5)(C14H13FNO)], crystallizes in the same space group with similar unit-cell parameters as the derivatives 3-anilino-1-ferrocenylpropan-1-one [Leka et al. (2012 ▶). Acta Cryst. E68, m229] and 1-ferrocenyl-3-(4-methylanilino)propan-1-one [Leka et al. (2012 ▶). Acta Cryst. E68, m230]. The dihedral angle between the best planes of the benzene ring and the substituted cyclopentadienyl ring is 83.4 (1)°. The presence of the electronegative fluoro substituent in the meta position of the aniline group does not alter the crystal packing compared to the other two derivatives. The molecules are connected into centrosymmetric dimers via N—H⋯O hydrogen bonds. In addition, C—H⋯O and C—H⋯N contacts stabilize the crystal packing.

1-Ferrocenyl-3-(2-methyl­anilino)propan-1-one

In the ferrocene-containing Mannich base, [Fe(C5H5)(C15H16NO)], the dihedral angle between the mean planes of the benzene ring and the substituted cyclopentadienyl ring is 84.63 (7)°. The conformation of the title compound significantly differs from those found in corresponding m-tolylamino and p-tolylamino derivatives. In the crystal, C—H⋯O interactions connect the molecules into chains, which further interact by means of C—H⋯π interactions. It is noteworthy that the amino H atom is shielded and is not involved in hydrogen bonding.