Two polymorphic modifications of 1-(N-morpholiniomethyl)spirobi- (3-oxo-2,5-dioxa-1-silacyclopentan)- ate hydrate

The compound 1-(N-morpholiniomethyl)spirobi(3-oxo-2,5-dioxa-1-silacyclopentan)ate crystallizes from aqueous solution of γ-butyrolactone in the form of two crystal hydrate modifications: monoclinic (with D = 1.53 g/cm³, space group P 2₁/n) and triclinic (D = 1.45 g/cm³, space group P1^-). For the monoclinic form, an X-ray structural study at -100°C has been performed. For both structures the coordination polyhedron of the silicon atom is a trigonal bipyramid. In the crystal structures there are strong intermolecular hydrogen bonds of NH···O and OH···O types.     

Crystal and molecular structure and electronic structure of a copper(II) complex with 10-(1-phthalazinylazo)-9-phenanthrol (HL) [Cu2(L)2(H2O)4](ClO4)2

The [Cu₂(L)₂(H₂O)₄](ClO₄)₂ compound (I) have been synthesized by the reaction of 10-(1-phthalazinylazo)-9-phenanthrol (HL) with tetraamminecopper(II) perchlorate, and its crystal and molecular structure has been determined by X-ray crystallography. The L anion acts as a tridentate chelating ligand and is coordinated to the Cu atom through the O(1) atoms of the phenanthrenequinone moiety, the N(1) atom of the phthalazinyl moiety, and the N(3) atom of the azo group to form two five-membered chelate rings. The coordination polyhedron of each Cu(1,2) atom is completed to a prolate tetragonal (4 + 1) pyramid by two water molecules with the O(2)(H₂O) atom in the axial position. The molecular and electronic structures of the HL molecule and [Cu(L)(H₂O)₂]⁺ ion have been determined by the density functional theory method. The results of quantum-chemical calculation are shown to fit well to the values found by X-ray crystallography.     

ab initio Calculation of the stereoelectronic structure of 1-(1-trichlorogermylethyl)-pyrrolidin-2-one*

RHF/6-31G(d) and MP2/6-31G(d) calculations were carried out to study the stereoelectronic structure of 1-(1-trichlorogermylethyl)pyrrolidin-2-one with a pentacoordinated germanium atom. These results were compared with the X-ray diffraction structural analysis data. Upon formation of the Ge ← O coordination bond in this molecule, the electron density of all the atoms of the coordination polyhedron of the germanium atom, including the oxygen atom, increases, especially the axial chlorine atom, while the electron density of the germanium, nitrogen, and carbonyl group carbon atoms decreases. Different polarization of all three valence p-orbitals of each Cl atom of this molecule was established. ³⁵Cl nuclear quadrupole resonance spectrum parameters were evaluated. The molecule also has stable form, in which the germanium atom is tetracoordinated. The total energy of this form is 2.7 kcal/mol higher than for the structure with a pentacoordinated germanium atom.     

Cu(II) and Cu(I) complexes with 2-(3,5-diphenyl-1H-pyrazole-1-yl)-4,6-diphenylpyrimidine: Synthesis and structure. Catalytic activity of Cu(II) compounds in reaction of ethylene polymerization

The Cu(II) and Cu(I) complexes with 2-(3,5-diphenyl-1H-pyrazole-1-yl)-4,6-diphenylpyrimidine (L) of the composition CuLX₂ (X = Cl, Br) and CuL(MeCN)Br are synthesized. According to X-ray diffraction data, the complexes have molecular structures. The molecules L are coordinated to the copper atom in bidentate-cyclic mode, i.e., through the N² atom of pyrazole and N¹ atom of pyrimidine rings. The coordination polyhedron of the Cu²⁺ ion in CuLX₂ compounds is completed to a distorted tetrahedron with halide ions, that of the Cu⁺ ion in CuL(MeCN)Br compounds, with the bromide ion and the nitrogen atom of acetonitrile molecule. The CuLX₂ complexes (X = Cl, Br) in combination with cocatalysts (methylaluminoxane and triisobutylaluminium) exhibit catalytic activity in ethylene polymerization.     

Unusual crystal and molecular structure of the 1-(1-silatranylmethyl)-3,5-dimethylpyrazole complex with zinc dichloride

The crystal and molecular structure of a 1-(1-silatranylmethyl)-3,5-dimethylpyrazole complex with zinc dichloride (I) is determined by XRD. The coordination polyhedron of the zinc atom is a tetrahedron formed by two covalent Zn-Cl bonds and coordination Zn ← N and Zn ← O bonds. Compound I is the first example of how an endocyclic oxygen atom of the silatranyl fragment participates in the coordination of the metal atom with the formation of a six-membered heterocycle.     

Investigation of structures of mono- and diorgano-substituted oligosiloxanes containing transition metal atoms

Oligomeric linear copper-containing diorganosiloxanes with a variable Cu : Si ratio and branched Cu- and Ni-containing organosiloxanes containing the γ-aminopropyl group at the Si atom were investigated. IR spectroscopic studies demonstrated that the distribution of metal atoms throughout the metallosiloxane chain in compounds with a high metal content (M : Si≥2) is rather uniform. According to the data from electronic spectroscopy, compounds under study are complexes of metal ions characterized by d-d transitions and an octahedral configuration of the coordination units. The Cu^II and Ni^II ions are coordinated by the NH₂ groups primarily through interchain interactions. ESR spectroscopic studies demonstrated that the Cu^II ions are located predominantly in the main chain to form −O−Cu−O− fragments. The coordination polyhedron changes from a nearly planar square (in the solid phase) to an elongated tetragonal bipyramid (in solution). The spectral parameters of the Cu-containing oligomer containing the γ-aminopropyl group at the Si atom indicate that the N atoms of the amino groups are located in the equatorial plane of the Cu-containing coordination polyhedron. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1813–1817, October, 2000.     

Etude des composés d'addition des acides de Lewis - XXXV. Note sur les composés d'addition entre amides et,respectivement, PdCl2 et PtCl2

The adducts of dimethylformamide, diethylformamide, dimethylacetamide and diethylacetamide with PdCl₂ and PtCl₂ have been prepared and the IR. spectra of the compounds in nujol mull or in CH₂Cl · CH₂Cl solution are studied. The lowering of the carbonyl frequency (amide I) shows that the metal is linked by a dative bond to the amide oxygen atom acting as a donor; the lowering is about 33 to 59 cm^?1. The decrease of the frequency of the carbonyl group vibration, observed in these cases as for other addition compounds of Lewis acids, is due to an intramolecular electronic displacement in the direction of the amid oxygen atom.     

The copper(II) acetate complex with 2-(2-Hydroxyphenyl)-4,4-diphenyl-1,2-dihydro-4H-3,1-benzoxazine

The Cu(II) acetate complex with 2-(2-hydroxyphenyl)-4,4-diphenyl-1,2-dihydro-4H-3,1-benzoxazine (L) was synthesized for the first time and structurally studied by X-ray diffraction. The complex crystallizes as two crystallographically independent centrosymmetric binuclear molecules [Cu₂(μ-L)₂Ac₂] of similar structure, where L occurs as azomethin tautomeric form. The ligand performs tridentate chelate-bridging function. Each Cu atom exhibits extended tetragonal-pyramidal coordination by two O atoms and the N atom of one ligand L in the equatorial plane and by the O atom of the second ligand L in the axial position. The fourth equatorial position in the metal coordination polyhedron is occupied by the O atom of monodentate terminal acetate group.     

Trigonal-bipyramidale Heterometallatomcluster vom Typ closo-Fe3(CO)9-[μ3- MRe(CO)5]2 (M = Ge,Sn)

Trigonal Bipyramidic Heteronuclear Metal Atom Clusters of the Type closo-Fe₃(CO)₉-[μ₃- MRe(CO)₅]₂ (M = Ge, Sn) The diamagnetic title compounds were prepared by the reaction of SnCl₂ (or Ge/GeCl₄), MnRe(CO)₁₀, and Fe(CO)₅ at 220°C in a glass tube. The result of the single crystal X-ray analysis of Fe₃(CO)₉[μ₃-SnRe(CO)₅]₂ showed that the triangular molecular fragment of Fe₃(CO)₉ with a fac-CO ligand arrangement at each Fe atom was capped by two μ₃-SnRe(CO)₅ groups forming a trigonal bipyramidic metal atom polyhedron. The characterization of its Sn? Re bond length [av. 272,6(2) pm] was undertaken by comparison with that of Cl₂Sn[Re(CO)₅]₂ [277.9(4) pm] obtained from a further structural determination. This type of polyhedron with Ge^IV and transition metal atoms bonds was before unknown. The ν(CO) i.r. absorption bands of both heteronuclear metal atom clusters and their electron absorption bands above λ = 350 nm were measured.     

Synthesis and crystal and molecular structure of the complex Zn(Phen)(S2COC4H9-i)2

A mixed-ligand complex Zn(Phen)(S₂COC₄H₉-i)₂ was synthesized. The single crystals of the complex were studied by X-ray diffractometry. The crystals are orthorhombic, a = 20.053(2), b = 19.272(2), c = 13.203(1) A, V_cdl = 5102.5(8) ų, space group Pcab, Z = 8, d_calc = 1.416 g/cm³, R = 0.059. The structure consists of monomeric molecules in which the coordination polyhedron of the central Zn atom is a distorted octahedron (CN = 6). An analysis of molecular packing and intermolecular distances showed that the molecules related by the symmetry center are involved in pronounced intermolecular interactions.     

Steric and electronic structure of 2-alkoxyphenyltrichlorostannanes according to results of ab initio calculations

Steric and electronic structure of 2-methoxy- and 2-ethoxyphenyltrichlorostannanes, as well as of 2-methoxyphenyltrichlorostannanes substituted in the ring, was studied using the RHF and B3LYP levels with the 3?C21G* basis set. The results of calculations were compared with experimental ³⁵Cl NQR data. In all studied molecules the Sn atom is pentacoordinated. The structure of the coordination polyhedron is a highly distorted trigonal bipyramid. Replacing methyl group in the alkoxy substituent involved in the Sn??O coordinating interaction by a more electron-donor ethyl group increases the strength of the Sn??O coordination bond. The same occurs also at the introduction of an electron-releasing substituent in the aromatic ring.     

Crystal and molecular structure of 5,5-BIS(hydroxymethyl)-2-OXO-2-[l-(2-trifluoromethyl-3,3,3-trifluoropropioneamido)-1-trifluoromethyl-2,2,2-trifluoroethyl]-1,3,2-dioxaphosphorinane

The crystal and molecular structure of 5,5-bis(hydroxymethyl)-2-oxo-2-[1-(2-trifluoromethyl-3,3,3-tri-fluoropropioneamido)-1-trifluoromethyl-2,2,2-trifluoroethyl]-1,3,2-dioxaphosphorinane (I) - an effective inhibitor of phosphorolytic enzymes - has been determined by X-ray diffractometry. Crystals I are monoclinic: space group P2₁/c, a = 9.962(3), b = 20.468(3), c = 9.527(3) å, Β = 108.04(2)?, Z = 4; R = 0.061 for 3065 independent reflections with I ≥ 3Σ. In a sterically strained molecule I, the coordination polyhedron of the P atom is a distorted tetrahedron with an elongated exocyclic P-C bond [1.906(2) å]. The six-membered heterocycle of I has a distorted chair conformation with a significantly flattened angle at the P atom. In the crystal structure, molecules I are linked into centrosymmetric H-dimers by a pair of strong H-bonds of O-H...O=P type and also into infinite (along the z axis) chains by H-bonds of N-H...O = C and C-H...O = C type.     

Neodymium(III) triaquatrihydroxo(1,3-diamino-2-propanoltetraacetato)germanium(IV) hydrate [Ge(OH)(μ-HHpdta)(μ-OH)Nd(OH)(H<Subscript>2</Subscript>O)<Subscript>3</Subscript>] · H<Subscript>2</Subscript>O: Synthesis and crystal and molecular structure

The heteronuclear germanium(IV) and neodymium(III) complex with 1,3-diamino-2-propanoltetraacetic acid (H₅Hpdta) [Ge(OH)(μ-HHpdta)(μ-OH)Nd(OH)(H₂O)₃] · H₂O has been synthesized for the first time and characterized by physicochemical methods (elemental analysis, X-ray powder diffraction, thermogravimetry, IR spectroscopy, X-ray crystallography). The crystals are monoclinic: a = 9.331(3) Å, b= 10.279(4) Å, c = 21.474(7) Å, β = 94.59(3)°, V = 2053.0(12) ų, Z = 4, space group P2₁/n, R1 = 0.0245 for 4060 reflections with I > 2σ(I). The compound is built of complex binuclear molecules [Ge(OH)(μ-HHpdta)(μ-OH)Nd(OH)(H₂O)₃] and water molecules of crystallization. The germanium and neodymium atoms are bridged by the oxygen atom of the hydroxo group (Ge-O, 1.798(2) Å; Nd-O, 2.539(2) Å) and the deprotonated oxygen atom of the isopropanol group of the HHpdta^4? ligand (Fe-O, 1.858(2)Å; Nd-O, 2.420(2) Å) to form a dimeric molecule. Each coordination sphere (of the Ge atom and of the Nd atom) contains one nitrogen atom (Ge-N, 2.096(3) Å; Nd-N, 2.807(2) Å) and two carboxylic oxygen atoms from four acetate branches of the octadentate HHpdta^4? ligand (av. Ge-O, 1.928(2) Å; Nd-O, 2.391(2) Å). The coordination polyhedron of the Ge atom is completed to a distorted octahedron by the oxygen atom of the terminal hydroxo group (Ge-O 1.811(2) Å), and the polyhedron of the Nd atom is completed to a nine-vertex polyhedron by the oxygen atoms of the terminal hydroxo group (Nd-O 2.494(3) Å) and three water molecules (Nd-O, 2.512(3), 2.520(3), and 2.723(3) Å). In the crystal structure, the complex molecules and the water molecules of crystallization are joined by a hydrogen bond system.     

Cleavage of 3-amino-o-carborane and its' N-derivatives by bases into the 3-amino-7,8-dicarbaundecaborate anion and its N-derivatives

Cleavage of 3-amino-o-carborane by alcoholic alkali results in preferential elimination of the boron atom from position six of the polyhedron with the formation of a salt of 3-amino-7,8-dicarbaundecaborate and, to a smaller degree, to elimination of the boron bonded to the NH₂ group, which leads to formation of a salt of 7,8-dicarbaundecaborate. Cleavage of 3-amino-o-carborane by piperidine is even more regioselective. Cleavage of N-derivatives of 3-amino-9-carborane by alcoholic alkali or piperidine is regiospecific, leading to salts of N-substituted 7,8-dicarbaundecaborates. 3-Ammonium-7,8-dicarbaundecaborate and a number of its N-derivatives were isolated in zwitterion form for the first time.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1145–1151, May, 1991.     

Synthesis and characterization of heteronuclear germanium(IV) and lanthanum(III) (chromium(III)) complexes with 1,3-diamino-2-propanoltetraacetic acid: Crystal and molecular structure of [Ge(OH)(μ-Hpdta)(μ-OH)La(H2O)4] · H2O

Two heteronuclear germanium(IV) and lanthanum(III) (chromium(III)) complexes with 1,3-diamino-2-propanoltetraacetic acid (H₅Hpdta) have been synthesized. The compounds have been characterized by elemental analysis and X-ray powder diffraction data. The structure of [Ge(OH)(??-Hpdta)(??-OH)La(H₂O)₄] · H₂O (I) has been determined by X-ray crystallography. The crystals are monoclinic, a = 9.3805(3) ?, b = 10.3023(4) ?, c = 21.6527(6) ?, ?? = 94.829(2)°, V = 2085.10(12) ?³, Z = 4, space group P2₁/n, R1 = 0.0294 based on 5480 reflections with I > 2??(I). Compound I is composed of binuclear [Ge(OH)(??-Hpdta)(??-OH)La(H₂O)₄] molecules and crystal water molecules. In the dimeric molecule, the germanium and lanthanum atoms are linked by the bridging oxygen atom of the hydroxo ligand and the oxygen atom of the deprotonated isopropanol group of Hpdta^5?. The coordination spheres of germanium and lanthanum each contains one nitrogen atom and two carboxyl oxygen atoms of the four acetate arms of the heptadentate Hpdta^5? ligand. The Ge coordination polyhedron is completed to a distorted octahedron by the oxygen atom of the terminal hydroxo group, and the lanthanum coordination polyhedron is completed to a nine-vertex polyhedron by the oxygen atoms of four water molecules. In crystal, the complex molecules and crystal water molecules are combined by a system of hydrogen bonds.     

Synthesis,structure, and properties of coordination compounds of copper(II) acetate with substituted 2-{[2-(2-hydroxyethylamino)ethylimino]methyl}phenol

Salicylic, 5-chloro-5-bromo-5-nitro-, 3-methoxysalicylic, 2-hydroxy-1-naphthoic aldehydes and 2,3-, 2,4-, and 2,5-dihydroxybenzaldehyde were shown to react in ethanol with 2-(2-aminoethylamino)ethanol in the presence of copper acetate hydrate forming coordination compounds Cu(L^1-9)CH₃COO {HL^1-8, 2-([2-(2-hydroxyethylamino)ethylimino]methyl}phenol (HL¹) and respective chloro(HL²), bromo- (HL³), nitro- (HL⁴), methoxy- (HL⁸), or hydroxy-substituted (HL^5-7); HL⁹, 2-{[2-(2-hydroxyethylamine)ethylimino] methylnaphthol)}. Structure of the complex Cu(L³)CH₃COO was determined by X-ray diffraction analysis. Coordination polyhedron of its central atom is a distorted tetragonal bipyramid with (4+1+1) modes of coordinating the copper atom. The bipyramid base is formed by the atoms of phenol oxygen and of azomethine and imine nitrogen atoms of the ligand (HL³) and the oxygen atom of the acetate ion. Axial apices of the bipyramid are occupied by the alcohol oxygen atoms of the azomethine (HL³) and the second oxygen atom of the acetate ion. Other complexes are also of monomer structure. Azomethines (HL^1-9) behave as monodeprotonated tetradentate O,N,N,O ligands. The thermolysis of substances includes a stage of complete thermal decomposition (360–530°C). Synthesized complexes show selective antimicrobial activity against a series of standard strains of Staphylococcus aureus and E. coli at the concentration in the range of 75–300 μg ml⁻¹.     

Synthesis,crystal structure,and electronic structure of a copper(II) chloride complex with 9(E)-phenanthrene-9,10-dione[(1Z)-3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]hydrazone [Cu2(L-H)2Cl2]

The [Cu₂(L-H)₂Cl₂] compound (I) has been obtained by the reaction of 9(E)-phenanthrene-9,10-dione[(1Z)-3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]hydrazone with copper(II) chloride. The crystal and molecular structure of I has been determined by X-ray crystallography. The L-H anion acts as a tridentate chelating ligand and is coordinated to the Cu atom through the O(1) atoms of the phenanthrenequinone moiety, the N(1) atom of the dihydroisoquinoline moiety, and the N(3) atom of the azo group to form two five-membered chelate rings. Complex I is a dimer with a double chloride bridge. The coordination polyhedron of the Cu atom is completed to a distorted pyramid by two chlorine atoms. The molecular and electronic structures of the L molecule and the model [Cu(L-H)Cl] complex have been determined by the density functional theory method. Spectroscopic characteristics of I have been determined.     

Coordination Compounds of Copper(II) Nitrate with Products of Aminotris(hydroxymethyl)methane Condensation with Salicyl- and 5-Nitrosalicylaldehydes: Synthesis and Crystal Structures

The crystal structures of copper(II) nitrate complexes with 2-(2-hydroxybenzylideneamino)-2-hydroxymethylpropane-1,3-diol (HL) and 2-hydroxymethyl-2-(2-hydroxy-5-nitrobenzylideneamino)propane-1,3-diol (HL¹) were determined. The resulting complexes were formulated as [Cu₃OL₃(H₂O₂]NO₃ · 3H₂O (I) and [Cu(H₂O)L¹]NO₃ (II). The crystals of I are monoclinic, a = 17.809(4) Å, b = 30.549(6) Å, c = 18.962(4) Å, β = 115.36(3)°, space group Cc, Z = 8, R = 0.0482. Complex I is composed of two independent three-dimensional µ₃-oxo complexes; the coordination polyhedron of the copper atoms in both compounds is an elongated tetragonal bipyramid. The coordination polyhedron of the third Cu atom is a tetragonal pyramid. The bases of the pyramids are composed of the oxygen atoms of the phenol and alcohol OH groups, the imine N atom of ligand L, and µ ₃-oxo atoms. The phenol and water O atoms serve as the apices in both the tetragonal bipyramids. The crystals of II are triclinic, a = 6.062(1) Å, b = 7.701(2) Å, c = 16.162(3) Å, α = 88.15(3)°, β = 84.94(3)°, γ = 78.13(3)°, space group P1¯, Z = 2, R = 0.0272. Complex II is composed of polymer chains formed by coordination bonds between the copper atom and two O atoms of the amino alcohol in the azomethine of the neighboring complex connected to the initial one by translation along the x axis. These chains are linked through hydrogen bonds involving the oxygen atoms of the NO₂ groups. The benzene rings of the azomethine ligands of the adjoining complexes from different chains are antiparallel to each other. The coordination polyhedron of the central atom is an elongated tetragonal bipyramid. Its equatorial plane is formed by the phenol O atom, one of the alcohol O atoms, the N atom of ligand L¹, and the O atom of the amino alcohol in the neighboring complex. The apices are the O atom of the water molecule and the O atom of the amino alcohol in the neighboring azomethine molecule. In complexes I and II, the outer-sphere nitrato group mainly serves to unite trimers and polymers in the crystal by means of hydrogen bonds.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 8, 2005, pp. 621–629.Original Russian Text Copyright © 2005 by Chumakov, Tsapkov, Simonov, Antosyak, Bocelli, Perrin, Starikova, Samus, Gulea.     

Synthesis and structure of new copper(II) coordination compounds with 8-quinoline aldehyde semicarbazones and thiosemicarbazones

Copper(II) salts were reacted with various quinoline aldehyde chalcogensemicarbazones to yield compounds formulated as Cu(HL)X₂ · nH₂O (I: HL = quinoline aldehyde thiosemicarbazone (HL¹), X = ClO₄, n = 2; II: HL = quinoline aldehyde 4-C₂H₅-thiosemicarbazone (HL^1a), X = NO₃, n = 0; III: HL = quinoline aldehyde semicarbazone (HL²), X = ClO₄, n = 3 and IV: HL = quinoline aldehyde 4-Ph-semicarbazone (HL^2a), X = NO₃, n = 1). Regardless of the reagent ratio, the products were compounds having the metal: ligand ratio of 1: 1, where the organic ligand was coordinated tridentate in a molecular form. Single-crystal X-ray diffraction showed that, depending on the chalcogen atom in the organic ligand (S or O), the substituent in the 4th position (at the terminal nitrogen atom), and the specifics of the acido ligand, complexes I–IV had appreciably differing molecular structure organizations. The structures of I and III are formed by a 1D charged coordination polymer, ClO ₄ ^? anions, and water molecules and may be described by the formula [Cu(HL)(H₂O)(ClO₄)] _n (ClO₄) _n · nH₂O. Copper(II) coordination polyhedra in I and II are (4 + 2) and (4 + 1 + 1) tetragonal bipyramids, respectively. In II and IV, the structures are monomeric and can be described as [Cu(HL^1a)(NO₃)₂] with the metal coordination polyhedron shaped as a (4 + 1) tetragonal pyramid in II and as [Cu(HL^2a)(H₂O)(NO₃)](NO₃) with the metal coordination polyhedron shaped as a (3 + 2) trigonal bipyramid in IV. The structure of II is built of molecular complexes, each comprising, apart from ligand HL^1a, two monodentate coordinated NO ₃ ^? groups. The oxygen atom of one anion together with the NNS donor atom set of ligand HL^1a form the base, and the oxygen atom of the other anion is in the apex of the coordination polyhedron. In IV, the structure is ionic and built of NO ₃ ^? anions and [Cu(HL^2a)(H₂O)(NO₃)]⁺ complex cations, where a cationic coordination polyhedron has a trigonal-bipyramidal configuration with organic ligand HL^2a positioned along the long edge. The bipyramidal base is made up by the oxygen atoms of the coordinated water molecule and monodentate nitrato group and the nitrogen atom N2 of the azomethyne group.     

X-ray crystal structure of a distorted tetrahedral cluster in the salt [(Ph3P)4Au4N]+ BF4−. Geometrical indication of stable electronic configurations in post-transition metal complexes and the magic number 18-e in centred gold clusters

According to an X-ray investigation (?120°C, λ(Mo-K_α), 6815 reflections, space group P2₁/c, Z = 4, R = 0.068), the cation of the tetraaurated ammonium salt [(Ph₃PAu)₄N]⁺ BF₄^? can be considered as a distorted tetrahedral Au₄(N) cluster built up of four linearly coordinated Au atoms with an interstitial N atom (AuAu 3.012–3.504 Å, AuN 1.93–2.10 Å). On the basis of the structural data on 14-, 16- and 18-electron mononuclear post-transition metal complexes, the magic number of 18 skeletal electrons can be suggested for [Au_nL_{n ? 1}]^m+ clusters with an interstitial Au atom and a quasi-spherical peripheral Au_{n ? 1} polyhedron.