Substitution reactivity and structural variability induced by tryptamine on the biomimetic rhenium tricarbonyl complex.

A series of seven fac-[Re(CO)3(5Me-Sal-Trypt)(L)] complexes containing tryptamine on the N,O 5-methyl-salicylidene bidentate ligand backbone and where L is MeOH, Py, Imi, DMAP, PPh3 coordinated to the 6th position have been studied, including the formation of a dinuclear Re2 cluster. The crystallographic solid state structures show marked similarity in structural tendency, in particular the rigidity of the Re core and the hydrogen bond interactions similar to those found in protein structures. The rates of formation and stability of the complexes were evaluated by rapid time-resolved stopped-flow techniques and the methanol substitution reaction indicates the significant activation induced by the use of the N,O salicylidene bidentate ligand as manifested by the second-order rate constants for the entering nucleophiles. Both linear and limiting kinetics were observed and a systematic evaluation of the kinetics is reported clearly indicating an interchange type of intimate mechanism for the methanol substitution. The anticancer activity of compounds 1-7 was tested on HeLa cells and it was found that all compounds showed similar cytotoxicity where solubility allowed. IC50-values between ca. 11 and 22 µM indicate that some cytotoxicity resides most likely on the salicylidene-tryptamine ligand. The photoluminescence of the seven complexes is similar in maximum emission wavelength with little variation despite the broad range of ligands coordinated to the 6th position on the metal centre.

2,6-Dichloro-aniline-4-(2,6-dichloro-anilino)-pent-3-en-2-one (1/2).

The asymmetric unit of the title compound, C6H5Cl2N·2C11H11Cl2NO, is composed of one mol-ecule of an enamino-ketone [i.e. -(2,6-dichloro-phenyl-amino)-pent-3-en-2-one] and half a mol-ecule of 2,6-dichloro-aniline, the whole mol-ecule of the latter component being generated by twofold rotational symmetry. In this latter mol-ecule, there are two intra-molecular N-H⋯Cl contacts. In the enamino-ketone mol-ecule, there is an N-H⋯O hydrogen bond of moderate strength, and the dihedral angle between the benzene ring and penta-none fragment [C-C(-N)=C-C(=O)-C; planar within 0.005 (1) Å] is 81.85 (7)°. In the crystal, two mol-ecules of the enamino-ketone are bridged by a mol-ecule of 2,6-dichloro-aniline via N-H⋯O hydrogen bonds of moderate strength. There are also π-π inter-actions present, involving the benzene rings of inversion-related enamino-ketone mol-ecules [centroid-centroid distance = 3.724 (4) Å].

4-(2,3-Dimethyl-anilino)pent-3-en-2-one.

In the title compound, C(13)H(17)NO, the dihedral angle between the aryl ring and the amino-acryl-aldehyde mean plane [N-C=C-C=O; maximum deviation = 0.0144 (9) Å] is 53.43 (4)°. There is an intra-molecular N-H⋯O hydrogen bond involving the amine and carbonyl groups. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming chains propagating along [001].

Dicarbon-yl[4-(2,6-dimethyl-phenyl-amino)-pent-3-en-2-onato-κ(2)N,O]rhodium(I).

In the title compound, [Rh(C(13)H(16)NO)(CO)(2)], a square-planar coordination geometry is observed around the Rh(I) atom, formed by the N and O atoms of the bidentate ligand and two C atoms from two carbonyl ligands. The Rh(I) atom is displaced from the plane through these surrounding atoms by 0.0085 (2) Å. The dihedral angle between the benzene ring and the N-C-C-C-O plane is 89.82 (6)°, and the N-Rh-O bite angle for the bidentate ligand is 90.53 (6)°. An inter-molecular C-H⋯O inter-action is observed between a methyl group of the benzene ring and a carbonyl O atom.

4-(2-Chloro-phenyl-amino)-pent-3-en-2-one.

In the title compound, C(11)H(12)ClNO, intra-molecular N-H⋯O hydrogen bonding is present. The dihedral angle between the benzene ring and the pentenone unit is 46.52 (5)°. In the crystal, C-H⋯O inter-actions between hydrogen atoms of the aryl moiety and two separate oxygen atoms occur, leading to a three-dimensional network.

4-(2,6-Dibromo-4-fluoro-anilino)pent-3-en-2-one.

The title enamino-ketone, C(11)H(10)Br(2)FNO, has a roughly planar pentenone chain; the maximum displacement of an atom from the pentenone plane is 0.071 (4) Å. The dihedral angle between the benzene ring and the pentenone unit is 77.2 (1)°. Inter-molecular C-H⋯Br and C-H⋯O inter-actions, as well as an intra-molecular N-H⋯O inter-action, are observed. In both methyl groups, each H atom is disordered equally over two sites.

4-(2-Methyl-anilino)pent-3-en-2-one.

The title enamino ketone, C(12)H(15)NO, a derivative of 4-(phenyl-amino)-pent-3-en-2-one, presents a roughly planar [greatest displacement of an atom from the pentenone plane is 0.033 (2) Å] pentenone backbone, enhanced by an intra-molecular N-H⋯O hydrogen bond; the asymmetry in C-C distances in the group suggests the presence of unsaturated bonds. The overall geometry in the free ligand differs significantly from that in other reported compounds, in which it is coordinated to rhodium; this is reflected in the bond distances [the N⋯O distance is significantly increased (0.2 Å) upon coordination to the metal] and the dihedral angle between the benzene ring and the pentenone backbone [49.53 (5)°]. All of the methyl goups are rotationally disordered over two orientations of equal occupancy.

4-[(4-Methyl-phen-yl)amino]-pent-3-en-2-one.

The title enamino-ketone, C(12)H(15)NO, is a derivative of 4-(phenyl-amino)-pent-3-en-2-one with an approximately planar pentenone backbone, the greatest displacement from the plane being 0.042 (1) Å; the asymmetry in C-C distances in the group suggests the presence of unsaturated bonds. The dihedral angle between the benzene ring and the pentenone plane is 29.90 (4)°. In the crystal, an intra-molecular N-H⋯O inter-action and an inter-molecular C-H⋯O hydrogen bond are observed.

Isomorphism in monomeric 1:3 complexes of silver(I) salts with tri-p-tolylphosphine.

Reaction of silver(I) salts with three equivalents of tri-p-tolylphosphine in CH(3)CN resulted in a series of isomorphous complexes [AgX{P(4-MeC(6)H(4))(3)}(3)] (X = Br, SCN, ClO(4)). These complexes all crystallize in the orthorhombic space group Pna2(1). The complexes with X = Br, SCN are distorted tetrahedral around the silver(I) atom, whereas the ClO(4)(-) complex is distorted trigonal planar around the silver. The new complexes are compared with each other using r.m.s. overlay calculations as well as half-normal probability plot analysis and with the previously reported isomorphous chloride, bromide as well as the non-isomorphous iodide complexes.

Polymorphism in iodotris(tri-p-tolylphosphine)silver(I).

The reaction of silver(I) iodide with tri(p-tolyl)phosphine in MeCN solution in 1:3 molar ratio yields a polymorph of the complex of the formula [AgI{P(4-MeC6H4)3}3], with the Ag atom in a distorted tetrahedral environment. A polymorphic structure of this complex (a) is compared with previously published crystal structures (b), determined at different temperatures. The two polymorphs are compared using r.m.s. overlay calculations as well as half-normal probability plots.

Carbon-yl[4-(2,3-dimethyl-phenyl-amino)pent-3-en-2-onato-κN,O](triphenyl-phosphine-κP)rhodium(I).

In the title compound, [Rh(C(13)H(16)NO)(C(18)H(15)P)(CO)], the coordination geometry of the Rh(I) atom is square-planar, formed by the coordinating N and O atoms of the bidentate enaminoketonate ligand, one C atom from the carbonyl group and a P atom from triphenyl-phosphine. The complex displays a 0.591 (3):0.409 (3) ratio disorder of the phenyl unit of the monoanionic N,O-bidentate ligand. Intra-molecular hydrogen bonding is observed between a C-H group of the triphenyl-phosphine unit and the O atom of the enamino-ketonate ligand.

Carbonyl[4-(2,6-dimethyl-phenyl-amino)pent-3-en-2-onato-κN,O](triphenyl-phosphine-κP)rhodium(I) acetone hemi-solvate.

In the title compound, [Rh(C(13)H(16)NO)(C(18)H(15)P)(CO)]·0.5C(3)H(6)O, the Rh atom exhibits a square-planar coordination geometry, being coordinated by the N and O atoms of the bidentate ß-diketonato ligand, a P atom from the triphenyl-phosphine unit and a C atom from the carbonyl group. The asymmetric unit also contains a disordered half-mol-ecule, lying about an inversion center, of the acetone solvate. Inter-molecular C-H⋯O hydrogen bonds are observed between a C-H group of the triphenyl-phosphine unit and a carbonyl O atom and between the methyl group of the enamino-ketonato backbone and the solvent O atom. In addition, an intra-molecular inter-action is observed between a C-H group of the triphenyl-phosphine unit and the O atom of the enamino-ketonato ligand.