Robust packing in cyclopalladated primary amines: isomorphous crystal structures of four complexes with varying substitution patterns.

The crystal structures of (SP-4-4)-[rac-2-(1-aminoethyl)phenyl-kappa(2)C(1),N]chlorido(pyridine-kappaN)palladium(II), [Pd(C(8)H(10)N)Cl(C(5)H(5)N)], (I), (SP-4-4)-[rac-2-(1-aminoethyl)phenyl-kappa(2)C(1),N]bromido(pyridine-kappaN)palladium(II), [PdBr(C(8)H(10)N)(C(5)H(5)N)], (II), (SP-4-4)-[rac-2-(1-aminoethyl)-5-bromophenyl-kappa(2)C(1),N]bromido(4-methylpyridine-kappaN)palladium(II), [PdBr(C(8)H(9)BrN)(C(6)H(7)N)], (III), and (SP-4-4)-[rac-2-(1-aminoethyl)-5-bromophenyl-kappa(2)C(1),N]iodido(4-methylpyridine-kappaN)palladium(II), [Pd(C(8)H(9)BrN)I(C(6)H(7)N)], (IV), are reported. The latter is the first iodide complex in this class of compounds. All four complexes crystallize in the same space group, viz. I4(1)/a, with very similar lattice parameters a and more flexible lattice parameters c. Their packing corresponds to that of their enantiomerically pure congeners, which crystallize in the t2 subgroup I4(1).

Reactivity of mononuclear Pd(ii) and Pt(ii) complexes containing the primary phosphane (ferrocenylmethyl)phosphane towards metal chlorides and PPh(3).

The reaction of the primary phosphane (ferrocenylmethyl)phosphane [PH(2)CH(2)Fc, ] with an equimolar amount of [M(cod)Cl(2)] (cod = 1,5-cyclooctadiene, M = Pd, Pt) gave the unusual monobridged M(ii) dinuclear complexes of formula [(cod)ClM(micro-PHCH(2)Fc)M(PH(2)CH(2)Fc)Cl(2)] [M = Pt, ; M = Pd, ]. The mechanism leading to and involves the preliminary formation of cis-[M(PH(2)CH(2)Fc)(2)Cl(2)] which further reacts with free [M(cod)Cl(2)] before undergoing dehydrochlorination. The reaction of with PPh(3) led to the unexpected formation of the cyclic trinuclear complex [Pd(3)(micro-PHCH(2)Fc)(3)(PPh(3))(2)(PH(2)CH(2)Fc)Cl(3)] (). Further reaction of with PPh(3) led to the substitution of the tertiary phosphane for the primary one with formation of two geometric isomers and of formula [Pd(micro-PHCH(2)Fc)(PPh(3))Cl](3) differing only for the position of the PPh(3) group replacing the PH(2)CH(2)Fc ligand. In complex each micro-PHCH(2)Fc group bridging two palladium atoms has a terminal PPh(3) ligand in trans position with respect to the first Pd (the cis position being occupied by a chlorine) and a chlorine ligand trans to the other Pd (the cis position being occupied by a terminal PPh(3) ligand) thus rendering chemically equivalent the three PPh(3) (and the three phosphides). In complex the three terminal PPh(3) as well as the three bridging phosphido ligands are chemically inequivalent. Complexes and coexist in equilibrium in solution, but only precipitates from CH(2)Cl(2)-n-hexane yielding crystals suitable for X-ray analyses. These crystals are water/n-hexane solvates and belong to the monoclinic space P2(1)/c with a = 25.063(6) A, b = 15.564(4) A, c = 26.089(5) A, beta = 120.017(16) degrees . They contain two identical couples of enantiomers of . The peculiar arrangement of three metals and three phosphorus atoms of the bridging ligands ascertained for trimers , and has no precedent in the rich class of palladium and platinum phosphido chemistry.

Site selectivity in the protonation of a phosphinito bridged Pt(I)-Pt(I) complex: a combined NMR and density-functional theory mechanistic study.

The protonation of the dinuclear phosphinito bridged complex [(PHCy2)Pt(mu-PCy2){kappa(2)P,O-mu-P(O)Cy2}Pt(PHCy2)] (Pt-Pt) (1) by Brønsted acids affords hydrido bridged Pt-Pt species the structure of which depends on the nature and on the amount of the acid used. The addition of 1 equiv of HX (X = Cl, Br, I) gives products of formal protonation of the Pt-Pt bond of formula syn-[(PHCy2)(X)Pt(mu-PCy2)(mu-H)Pt(PHCy2){kappaP-P(O)Cy2}] (Pt-Pt) (5, X = Cl; 6, X = Br; 8, X = I), containing a Pt-X bond and a dangling kappa P-P(O)Cy2 ligand. Uptake of a second equivalent of HX results in the protonation of the P(O)Cy2 ligand with formation of the complexes [(PHCy2)(X)Pt(mu-PCy2)(mu-H)Pt(PHCy2){kappaP-P(OH)Cy2}]X (Pt-Pt) (3, X = Cl; 4, X = Br; 9, X = I). Each step of protonation is reversible, thus reactions of 3, 4, with NaOH give, first, the corresponding neutral complexes 5, 6, and then the parent compound 1. While the complexes 3 and 4 are indefinitely stable, the iodine analogue 9 transforms into anti-[(PHCy2)(I)Pt(mu-PCy2)(mu-H)Pt(PHCy2)(I)] (Pt-Pt) (7) deriving from substitution of an iodo group for the P(OH)Cy2 ligand. Complexes 3 and 4 are isomorphous crystallizing in the triclinic space group P1 and show an intramolecular hydrogen bond and an interaction between the halide counteranion and the POH hydrogen. The occurrence of such an interaction also in solution was ascertained for 3 by (35)Cl NMR. Multinuclear NMR spectroscopy (including (31)P-(1)H HOESY) and density-functional theory calculations indicate that the mechanism of the reaction starts with a prior protonation of the oxygen with formation of an intermediate (12) endowed with a six membered Pt(1)-X...H-O-P-Pt(2) ring that evolves into thermodynamically stable products featuring the hydride ligand bridging the Pt atoms. Energy profiles calculated for the various steps of the reaction between 1 and HCl showed very low barriers for the proton transfer and the subsequent rearrangement to 12, while a barrier of 29 kcal mol(-1) was found for the transformation of 12 into 5.

Tris[4-(2-pyridylmethyl-eneamino)phenol]iron(II) bis-(perchlorate).

In the title compound, [Fe(C(12)H(10)N(2)O)(3)](ClO(4))(2), the metal center is coordinated by six N atoms from the three bidentate chelating ligands in a distorted octa-hedral coordination geometry, with overall formation of the meridional (OC-6-21) isomer. Inter-molecular O-H⋯O hydrogen bonds between the hydroxyl groups of the cation and the counter-anions form an infinite one-dimensional chain in the c-axis direction.