Margarita Gómez

Synthesis and Coordination Chemistry of Two N2-Donor Chelating Di(indazolyl)methane Ligands: Structural Characterization and Comparison of Their Metal Chelation Aptitudes

The N(2)-donor bidentate ligands di(1H-indazol-1-yl)methane (L(1)) and di(2H-indazol-2-yl)methane (L(2)) (L in general) have been synthesized, and their coordination behavior toward Zn(II), Cd(II), and Hg(II) salts has been studied. Reaction of L(1) and L(2) with ZnX(2) (X = Cl, Br, or I) yields [ZnX(2)L] species (1-6), that, in the solid state, show a tetrahedral structure with dihapto ligand coordination via the pyrazolyl arms. The reaction of L(1) and L(2) with Zn(NO(3))(2)·6H(2)O is strongly dependent on the reaction conditions and on the ligand employed. Reaction of L(1) with equimolar quantities of Zn(NO(3))(2)·6H(2)O yields the neutral six-coordinate species [Zn(NO(3))(2)(L(1))], 7. On the other hand the use of L(1) excess gives the 2:1 adduct [Zn(NO(3))(2)(L(1))(2)], 8 where both nitrates act as a unidentate coordinating ligand. Analogous stoichiometry is found in the compound obtained from the reaction of L(2) with Zn(NO(3))(2)·6H(2)O which gives the ionic [Zn(NO(3))(L(2))(2)](NO(3)), 10. Complete displacement of both nitrates from the zinc coordination sphere is observed when the reaction between L(1) excess and the zinc salt was carried out in hydrothermal conditions. The metal ion type is also determining structure and stoichiometry: the reaction of L(2) with CdCl(2) gave the 2:1 adduct [CdCl(2)(L(2))(2)] 11 where both chlorides complete the coordination sphere of the six-coordinate cadmium center; on the other hand from the reaction of L(1) with CdBr(2) the polynuclear [CdBr(2)(L(1))](n) 12 is obtained, the Br(-) anion acting as bridging ligands in a six-coordinate cadmium coordination environment. The reaction of L(1) and L(2) with HgX(2) (X = Cl, I, SCN) is also dependent on the reaction conditions and the nature of X, two different types of adducts being formed [HgX(L)] (14: L = L(1), 16, 17: L = L(1) or L(2), X = I, 19: L = L(2), X = SCN) and [HgX(L)(2)] (15: L = L(2), X = Cl, 18: L = L(1), X = SCN). The X-ray diffraction analyses of compounds 1, 2, 4, 5, 7, 8, 10-12, 14, 15, and 19 are also reported. The variations of the coordination geometry parameters in the complexes are compared and discussed.

Group 11 complexes with the bidentate di(1H-indazol-1-yl)methane and di(2H-indazol-2-yl)methane) ligands

Twenty-four new copper, silver and gold complexes based on a bis(pyrazolyl)methane ligand L (in detail L = L1, di(1H-indazol-1-yl)methane; L = L2, di(2H-indazol-2-yl)methane) are prepared. The [Cu(L)(PR3)2]X species have been obtained from the reaction of [CuX(PR3)2] with L upon the displacement of X from the copper coordination sphere. 1 : 1 [CuX2(L)] complexes were obtained when L1 reacts with CuX2 whereas under the same conditions, L2 gave the ionic species [CuX(L)2]X. When L1 reacts with CuCl2, however, the dinuclear [CuCl2(L1)]2 complex is formed which, upon treatment with dimethylformamide (DMF), gave the mononuclear derivative [CuCl2(L1)(DMF)]. L1 and L2 often show a different reactivity toward silver salts. For example, in the reaction with AgNO3, the ionic compound [Ag(L1)2]NO3 is obtained when L1 is used as a starting reagent and the neutral 1 : 2 adduct [AgONO2(κ-L2)(κ2-L2)] containing a mono and a bidentate ligand is formed when L2 is employed as a ligand. L1 gave 2 : 1 adducts with AgCX3SO3 (X = H or F) and AgClO4, whereas 1 : 1 adducts are formed under the same conditions with L2. L1 and L2 give analogous dinuclear ([Ag(O2CCF3)(L)]2) and mononuclear ionic species ([Ag(L)2]BF4) when they react with Ag(O2CCF3) and AgBF4 species. Two analogous gold(III) complexes [AuCl2(L)][AuCl4] have also been obtained in the reaction of L with AuCl3 when the reaction was carried out in an excess of the ligands. All the air- and thermally stable complexes have been characterized by analytical and spectral (IR, conductivity, ESI-MS, 1H and 13C NMR solution data) methods.

Group 9 and 10 complexes with the bidentate di(1H-indazol-1-yl)methane and di(2H-indazol-2-yl)methane ligands: synthesis and structural characterization

Novel [MX2(L)2], [MX2(L)], [M(L)2]X2 and [MX(H2O)3(L)]X derivatives were obtained by interaction of MX2 (M = Co(II), X = Cl; M = Ni(II), X = Cl; M = Pd(II), X = Cl or CH3COO) with chelating L ligands (L in general, in detail L1 = bis(1H-indazol-1-yl)methane, L2 = bis(2H-indazol-2-yl)methane). With PdCl2 as an acceptor the more hindered L2 ligand affords an ionic complex of composition [Pd(L2)2]Cl2, while a neutral species of composition [PdCl2(L1)] has been isolated with L1. Whereas, by using Pd(OOCCH3)2 as an acceptor, neutral complexes of general formula [Pd(OAc)2(L)] have been isolated with both L1 and L2 ligands. All the palladium complexes adopt a slightly distorted square planar geometry, as confirmed by three X-ray structures. Additional hydrated species, one of Co(II) and the other of Pd(II), were isolated from attempts of crystallization carried out in the air, and that of cobalt displays an interesting metal environment where a L1 and a Cl are replaced by three water molecules giving rise to an ionic species, where intermolecular electrostatic interactions, intermolecular hydrogen bonds and the intermolecular aromatic interactions between the indazole groups in neigbouring L1 ligand assemble the cobalt species into a three-dimensional network.

(Butane-1,4-di­yl)(trimethyl­phosphane-κP)[tris­(3,5-dimethyl­pyrazol-1-yl-κN2)hydro­borato]iridium(III)

In the mononuclear title iridium(III) complex, [Ir(C4H8)(C15H22BN6)(C3H9P)], which is based on the [tris(3,5-dimethylpyrazol-1-yl)hydroborato]iridium moiety, Ir[TpMe2], the IrIII atom is coordinated by a chelating butane-1,4-diyl fragment and a trimethylphosphane ligand in a modestly distorted octahedral coordination environment formed by three facial N, two C and one P atom. The iridium–butane-1,4-diyl ring has an envelope conformation. This ring is disordered because alternately the second or the third C atom of the butane-1,4-diyl fragment function as an envelope flap atom (the occupancy ratio is 1:1). In the crystal, molecules are organized into densely packed columns extending along [101]. Coherence between the molecules is essentially based on van der Waals interactions.