Stephen R. Foley

Synthesis and structural characterization of the first trialkylguanidinate and hexahydropyramidopyramidinate complexes of tin

Abstract The first guanidinate complexes of tin have been prepared using N,N′,N′′-trialkylguanidinates ([(RN)2C(NRH)]−; R=cyclohexyl; isopropyl) and 1,3,4,6,7,8-hexahydro-2H-pyramido[1,2-a]pyramidinate (hpp−) as ligands. The direct reaction between triisopropylguanidine and SnCl4 provided the complex {[iPrN]2C[NHiPr]}SnCl3 (1) along with concomitant formation of the guanidinium salt {C[NHiPr]3}+[SnCl5(THF)]− (2). The Sn(II) guanidinate complexes {(C6H11N)2C[NH(C6H11)]}2Sn (3) and {CN[N(CH2)3]2}2Sn (4) were prepared through metathesis reactions between 0.5 equiv. SnCl2 and (C6H11N)2C[NH(C6H11)]Li or hppLi, respectively. Complex 4 is the first reported mononuclear complex of this ligand. In contrast, the reaction of hppLi with 1 equiv. SnCl2 afforded a bridging dinuclear species, {CN[N(CH2)3]2SnCl}2 (5). A second mononuclear complex of the hpp− ligand, {CN[N(CH2)3]2}2SnCl2 (6), was the product obtained from the reaction of 2 equiv. of hppLi with SnCl4. The full structural details of compounds 1 and 3–6 are reported. In the case of compounds 1 and 3 these results revealed a distinctly unsymmetrical bonding mode for the bidentate guanidinate ligand and suggest variable degrees of π delocalization with the ligand. The geometries of the Sn centers in 3, 4 are derived from distorted trigonal bipyramidal coordination with a stereochemically active lone pair occupying one coordination site. In contrast, complex 5 displayed a geometry derived from a tetrahedral ligand array with one vertex occupied by a lone pair of electrons. Complex 6 is six coordinate and possesses 2 equiv. chelating bidentate hpp− ligands and two cis-chloro groups.

N-(2,6-Diisopropyl­phen­yl)formamide

The title compound, C13H19NO, exhibits a non-planar structure in which the 2,6-diisopropylphenyl ring is tilted at a dihedral angle of 77.4 (1)° with respect to the formamide group. This is the largest dihedral angle known among structurally characterized formamides. The molecules are linked via N—H⋯O hydrogen bonds, forming infinite chains which run along the b-axis directions.

Bis[2-phenyl-1-(phenyl­iminio)isoindo­line] di-μ-chlorido-bis­[dichloridopalladate(II)] benzene disolvate

In the title compound, (C20H17N2)2[Pd2Cl6]·2C6H6, the dichloride-bridged [Pd2Cl6]2− anion lies across an inversion center with each PdII ion in a slightly distorted square-planar environment. In the crystal structure, two cations and an anion are connected via N—H⋯Cl hydrogen bonds between the NH groups of the iminioisoindoline cations and terminal Cl atoms of a hexachloridodipalladate(II) anion. The Pd—Cl distance of the terminal chloride engaged in hydrogen bonding is slightly longer than the Pd—Cl distance of the adjacent terminal chloride which is not involved in hydrogen bonding.

Chalcogen atom transfer reactions. Kinetics of terminal bonded sulfur atom transfer between main group metal centers

The first comprehensive investigation of S atom transfer between two different metal centers is presented using the reaction of the terminal chalcogen atom bearing complex [CyNC(tBu)NCy]2SnS with [CyNC(tBu)NCy]2GeII; this multielectron redox reaction between GeII and SnIV proceeds via a second-order process with an inner sphere mechanism involving a μ-S intermediate as the proposed pathway; results of S and Se atom transfer between [CyNC(tBu)NCy]2Ge and PPh3 are also presented.

Iron guanidinate complexes and formation of a novel dinuclear iron(II) species with a dianionic μ-η2∶η2 (biguanidinate) ligand

Reaction of the lithium salt of N,N′,N″-triisopropylguanidinate with Fe(III) or Fe(II) halides led to isolation of the new species [(PriN)2C(HNPri)]2FeCl (1) and [μ-η2-(PriN)2C(HNPri)] 2{Fe[η2-(PriN)2C(HNPr i)]}2 (2); attempted alkylation of 1 with 1 equiv. of a variety of reagents produced 2; the reaction of 2 with LiCH2SiMe3 resulted in a coupling reaction between the two bridging ligands to yield [(μ-η2∶η2-(PriN)2 C)2NPri)]{Fe[η2-(PrNi )2C(HNPri)]}2.