Homoleptic Compounds Research Articles

N,N‐Dialkylcarbamato Metal Complexes, Molecular Inorganic Precursors to Functionalized Inorganic Matrices

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Homoleptic Zirconium Complex with Four Bulky η2-Pyrazolato Ligands

Two new tetrakisη2-pyrazolato) zirconium complexes are prepared from the reaction of Zr(CH2Ph)4 with bulky pyrazolate ligands bearing indenylmethyl (HL1) or fluorenylmethyl (HL2) substituents, respectively. Zr(L2)4 has been analyzed by X-ray crystallography, which represents the first structural characterisation of a homoleptic η2-pyrazolato zirconium compound.

Coordination chemistry of novel scorpionate ligands based on 3-cyclohexylpyrazole and 3-cyclohexyl-4-bromopyrazole.

The ligands [hydrotris(3-cyclohexylpyrazol-1-yl)borate, [Tp(Cy)](-), tetrakis(3-cyclohexylpyrazol-1-yl)borate, [pz(o)Tp(Cy)](-), and hydrotris(3-cyclohexyl-4-bromopyrazol-1-yl)borate, [Tp(Cy,4Br)](-) were synthesized and characterized as their Tl(I) derivatives. They were converted to a variety of tetrahedral LMX and octahedral LML' complexes, as well as to the dinuclear nickel carbonate complex [Ni(Tp(Cy))](2)(CO(3)), 4, and the compound Ni[Tp(Cy,4Br)][pz(Cy,4Br)](3)(H)(2), 5. The structures of Co[Tp(Cy)]Cl, 1, Co[Tp(Cy,4Br)]Cl, 2, Co[Tp(Cy,4Br)]NCS, 3, [Ni(Tp(Cy))](2)(CO(3)), 4, Ni[Tp(Cy,4Br)][pz(Cy,4Br)](3)(H)(2), 5, and Mo[Tp(Cy)](CO)(2)(eta(3)-methallyl), 6, were determined by X-ray crystallography. The structures of paramagnetic heteroleptic complexes Co[Tp(Cy)][Tp], Co[Tp(Cy)][Tp], Co[Tp(Cy,4Br)][Tp], and Co[Tp(Cy,4Br)][Tp] were established by NMR. The homoleptic compounds Co[Tp(Cy)](2) and Co[Tp(Cy,4Br)](2) rearrange thermally to Co[Tp(Cy)](2) and to Co[Tp((Cy,4Br))](2), respectively, containing one 5-cyclohexyl group/ligand.

Spatial Extensions of Excited States of Metal Complexes. Tunability by Chemical Variation

The ligand−ligand coupling in excited states of homoleptic metal−organic and related compounds of the platinum metal group depends strongly on the metal d or MLCT character in these states. In particular, in triplet states, which mostly represent the lowest excited states, the metal participation is displayed in the amount of zero-field splitting (zfs). Detailed investigations in recent years have demonstrated that complexes with very small metal participation and thus small zfs, like [Rh(bpy)3]3+ and [Pt(bpy)2]2+, exhibit spatially localized or ligand-centered triplets. Compounds with large metal character as in 3MLCT states have large zfs, and the states are delocalized over the metal and the different ligands, as found for [Ru(bpy)3]2+ and [Os(bpy)3]2+. By chemical variation, it is possible to obtain a compound characterized by an intermediate position between the two extreme situations. Such a compound is Pt(2-thpy)2 with 2-thpy- = 2-(2-thienylpyridinate). It is one of the main subjects of this investigation to study whether in Pt(2-thpy)2 the lowest excited triplet is spatially extended over both ligands. This is done by comparing highly resolved emission (and excitation) spectra of perprotonated Pt(2-thpy-h6)2, partially deuterated Pt(2-thpy-h6)(2-thpy-d6), and perdeuterated Pt(2-thpy-d6)2. These spectra display clear fingerprints with respect to spatial extensions of the excited states. The required high resolution is obtained when the compounds are dissolved in an n-octane matrix (Shpol'skii matrix) and are measured at low temperature (T = 1.3 and 4.2 K). The deuterated compounds are studied for the first time. Interestingly, it is found that all three triplet sublevels of Pt(2-thpy)2 are spatially extended over both ligands. This result is of high importance, since it tells us that already a moderate metal d or MLCT character in the lowest triplet state of homoleptic compounds of the platinum metal group leads, at least in a rigid matrix, to spatially delocalized excited states.

Synthesis characterisation and stability of mixed aryldichalcogenide bis(diphenylphosphino)ethanenickel(II) complexes. X-ray structure of Ni(dppe)(SeC 6H 4S)

Mixed chalcogenide complexes of the type Ni(dppe)(SeC 6H 4S) (dppe=bis(diphenylphosphino)ethane), Ni(dppe)(SC 5H 3NCO 2) and Ni(dppe)(EC 5H 3NE′) (E=NH, E′=O; E=E′=NH) have been prepared from the reactions of Ni(dppe)Cl 2 with the appropriate aryldichalcogen or pyridine-based compound, using Et 3N as a base. The relative solution and thermal stabilities of the above compounds, other mixed chalcogen ones, Ni(dppe)(SC 6H 4O), Ni(dppe)(SC 6H 4CO 2) and Ni(dppe)(SC 6H 4NH), and the homoleptic compounds Ni(dppe)(EC 6H 4E′) (E=E′=O, E=E′=S; R=H, Me), were established by a combination of electron impact mass spectrometry (EIMS) and fast atom bombardment (FABMS). The most stable ones were the compounds with homoleptic sulfur ligands.

Phosphane Complexes of Alkaline Earth Metals

The reaction of lithium[bis(dimethylphosphanyl)(trimethyl-silyl)methanide] Li[(PMe2)2C(SiMe3)] with BeCl2 gave the homoleptic compound Be[(PMe2)2C(SiMe3)]2 (5) with four beryllium–phosphorus bonds constituting a distorted tetrahedron around the beryllium center. The reaction of MgCl2 with Li[(PMe2)2C(SiMe3)] resulted in the formation of the bis-chelate complex Mg[(PMe2)2C(SiMe3)]2 · 2 THF (7), where the distorted cis-octahedral magnesium center is additionally coordinated by two THF ligands. In the reaction of 7 with an additional equivalent of Li[C(PMe2)2(SiMe3)], THF is released and the magnesate anion {Mg[(PMe2)2C-(SiMe3)]3}– (8) was obtained. This compound is not only the first reported hexacoordinated magnesate, but also the first magnesium compound with six magnesium–phosphorus bonds. With CaCl2 and Li[C(PMe2)2(SiMe3)], a heptacoor-dinated complex Ca[(PMe2)2C(SiMe3)]2 · 3 THF (10) with three coordinating THF ligands was isolated. The complexes were characterized using 9Be{1H}-, 31P{1H}-, 1H-, 13C{1H}-NMR spectroscopy, and elemental analysis and by X-ray diffraction. The neutral compounds are highly soluble in nonpolar solvents.

Co-ordination chemistry of 1,1′-bis(diphenylthiophosphoryl)ferrocene (dptpf ) towards silver(I). Crystal structure of the polymeric complex [Ag2(μ-dptpf ){(SPPh2)2CH2}2]n[ClO4]2n ‡

The ligand 1,1′-bis(diphenylthiophosphoryl)ferrocene, dptpf, reacted with various silver complexes to afford two-, three- or four-co-ordinate species. Thus the reaction of dptpf with [Ag(OClO3)(PPh3)] in 1∶1 or 1∶2 molar ratio gave the three-co-ordinate [Ag(dptpf)(PPh3)]ClO4 or the linear [Ag2(dptpf)(PPh3)2][ClO4]2 derivatives. Similarly, the treatment of dptpf with AgClO4 in 2∶1 or 1∶1 molar ratio afforded the homoleptic compounds [Ag(dptpf)2]ClO4 or [Ag(dptpf)]ClO4; in the latter dptpf acts as a trans-chelating ligand. The complex [Ag(dptpf)]ClO4 can react further with bidentate ligands such as 2,2′-bipyridine (bipy) or bis(diphenylthiophosphoryl)methane, (SPPh2)2CH2, leading to the four-co-ordinate [Ag(dptpf)(bipy)]ClO4 or the four-co-ordinate polymeric species [Ag2(µ-dptpf){(SPPh2)2CH2}2]n[ClO4]2n, which was characterised by X-ray diffraction.

Homoleptische Alkin—Nickel(0) Komplexe: Kombination von Nickel(0) Zentren mit Alkinylsilanen R n1Si(-C≡C-R 2) 4− n zu nickelorganischen Analoga von Siloxanen

(cod) 2Ni reacts with Ph 3Si-C≡C-CMe 3 to form the mixed complex (cod)Ni(alkyne) ( 1), (cdt)Ni and Ph 3Si-C≡C-CMe 3 yield the homoleptic compound (alkyne) 2Ni ( 2) (cod: cyclooca-1.5-diene, cdt: cyclododeca-1.5.9-triene). Both crystal structures were determined by X-ray diffraction analysis. In 2 the Ni(0) center is surrounded by the four carbon atoms of the alkynes yielding a distorted nickel-centered C 4 tetrahedron (NiC 4). Reaction of the alkynylsilanes Ph 2Si(-C≡C-R) 2 (R = CMe 3, SiMe 3) and of PhSi(− ≡C-CMe 3) 2 with (cdt)Ni gives dimeric compounds of the type [(alkinylsilane)Ni(0)] 2 ( 3–5), which have been characterized by X-ray diffraction determination. 3–5 show very similar structures in the solid state. Two silicon-centered C 4 tetrahedra (SiC 4) are connected with two NiC 4 tetrahedra by the four carbon atoms which are related to the two different kinds of tetrahedra. This structural principle can be compared with the structure of tetrasiloxanes. According to the temperature-dependent 13C NMR spectra of 5 several conformers can be detected in solution.

The insertion of chalcogen atoms into the InIn bond of tetrakis[bis(trimethylsilyl)methyl]diindane(4): monomeric compounds with InSIn, InSeIn, and InTeIn groups

The insertion of chalcogen atoms into the indium-indium bond of tetrakis[bis(trimethylsilyl)methyl]diindane(4)( 1) by the reaction of 1 with the chalcogen atom donors propylene sulphide, triethyl phosphonium selenide or telluride yields homoleptic compounds with up to now unknown R 2InSInR 2 ( 2), R 2InSeInR 2 ( 3), and R 2InTeInR 2 ( 4) groups. All products are monomeric, both in solution and in the solid state, as shown by the cryoscopically determined molar masses and crystal structure determinations. The indium-chalcogen-indium bridges are bent and exhibit angles of 112.4(1) and 116.8(2)° ( 2), 109.96(3)° ( 3), and 105.42(2)° ( 4).

The insertion of chalcogen atoms into Al-Al and Ga-Ga bonds: Monomeric compounds with Al-Se-Al, Ga-S-Ga and Ga-Se-Ga groups

The insertion of chalcogen atoms into the element-element bonds of tetraki[bis(trimethylsilyl)methyl]dialane(4) ( 1) and digallane(4) ( 2) by the reaction with the chalcogen atom donors triethyl phosphonium sulfide and selenide yields homoleptic compounds with novel R 2Al-Se-AlR 2 ( 3), R 2Ga-S-GaR 2 (4) and R 2Ga-Se-GaR 2 groups ( 5). All products are monomeric both in solution and in the solid state, as shown by the cryoscopically determined molar masses and crystal structure determinations. The element-chalcogen-element bridges are bent and exhibit angles of 114.71 ( 3), 117.04 ( 4) and 113.45° (5). Copyright © 1996 Elsevier Science Ltd

Solvent induced disproportionation of alkyl(amido)magnesium species containing a (2-pyridyl)amido unit: synthetic, theoretical and NMR spectroscopic studies of bis(amido)magnesium compounds

Reaction of R(2-pyr)NH (where R = Me, Ph or 2-pyr) with ‘Bu 2Mg’ in an ether-free environment yields the corresponding alkyl(amido)magnesium derivative [{R(2-pyr)NMgBu} n ]. When polar solvent is added to these species only bis(amido)magnesium compounds separate from solution and not the expected solvated alkyl(amido) derivatives. Isolation of one such alkyl(amido)compound prior to reaction with donor solvent proves that the mixed anion species do indeed exist. However, when polar molecules are introduced a disproportionation reaction ensues, yielding the homoleptic compounds [{R 2Mg · (S) x } n ] and [{(R 2N) 2Mg · (S) x } n ], where S is THF, TMEDA or PMDETA. Theoretical calculations likewise show that the disproportionation reaction of model compounds closely related to our systems is strongly exothermic. A 1H/ 13C NMR spectroscopic study was used to assign the nature of the bis(amido) species in solution. From these analyses it was possible to propose that the solvated bis(amido) derivatives assume a common structural motif, that of a monomer ( n = 1) with a pseudo-octahedral magnesium center.

Syntheses of Cationic, Six-Coordinate Cadmium(II) Complexes Containing Tris(pyrazolyl)methane Ligands. Influence of Charge on Cadmium-113 NMR Chemical Shifts

Treating a thf (thf = tetrahydrofuran) suspension of Cd(acac)(2) (acac = acetylacetonate) with 2 equiv of HBF(4).Et(2)O results in the immediate formation of [Cd(2)(thf)(5)](BF(4))(4) (1). Crystallization of this complex from thf/CH(2)Cl(2) yields [Cd(thf)(4)](BF(4))(2) (2), a complex characterized in the solid state by X-ray crystallography. Crystal data: monoclinic, P2(1)/n, a = 7.784(2) Å, b = 10.408(2) Å, c = 14.632(7) Å, beta = 94.64(3) degrees, V = 1181.5(6) Å(3), Z = 2, R = 0.0484. The geometry about the cadmium is octahedral with a square planar arrangement of the thf ligands and a fluorine from each (BF(4))(-) occupying the remaining two octahedral sites. Reactions of [Cd(2)(thf)(5)](BF(4))(4) with either HC(3,5-Me(2)pz)(3) or HC(3-Phpz)(3) yield the dicationic, homoleptic compounds {[HC(3,5-Me(2)pz)(3)](2)Cd}(BF(4))(2) (3) and {[HC(3-Phpz)(3)](2)Cd}(BF(4))(2) (4) (pz = 1-pyrazolyl). The solid state structure of 3 has been determined by X-ray crystallography. Crystal data: rhombohedral, R&thremacr;, a = 12.236(8) Å, c = 22.69(3) Å, V = 2924(4) Å(3), Z = 3, R = 0.0548. The cadmium is bonded to the six nitrogen donor atoms in a trigonally distorted octahedral arrangement. Four monocationic, mixed ligand tris(pyrazolyl)methane-tris(pyrazolyl)borate complexes {[HC(3,5-Me(2)pz)(3)][HB(3,5-Me(2)pz)(3)]Cd}(BF(4)) (5), {[HC(3,5-Me(2)pz)(3)][HB(3-Phpz)(3)]Cd}(BF(4)) (6), {[HC(3-Phpz)(3)][HB(3,5-Me(2)pz)(3)]Cd}(BF(4)) (7), and {[HC(3-Phpz)(3)][HB(3-Phpz)(3)]Cd}(BF(4)) (8) are prepared by appropriate conproportionation reactions of 3or 4 with equimolar amounts of the appropriate homoleptic neutral tris(pyrazolyl)borate complexes [HB(3,5-Me(2)pz)(3)](2)Cd or [HB(3-Phpz)(3)](2)Cd. Solution (113)Cd NMR studies on complexes 3-8 demonstrate that the chemical shifts of the new cationic, tris(pyrazolyl)methane complexes are very similar to the neutral tris(pyrazolyl)borate complexes that contain similar substitution of the pyrazolyl rings.

Synthetic, Characterization and Decomposition Studies of Indium Sulfide Precursors

ABSTRACTThe synthesis, characterization and decomposition of several indium thiolates containing the bulky substituted aryl ligand 2,4,6-i-Pr 3C6H2 (Ar′) or the internally chelating ligands 2-CH3O,5-CH3C6H3 (Ar″) and o-C6H4CH2N(CH3)2 (Ar"‘) are described. Two synthetic methods have been utilized: metathesis reactions between lithium thiolates and the appropriate metal halides and the addition of elemental metal to diaryl disulfides. The thermal decomposition of each indium precursor results in the formation of 1n2S3, based on thermogravimetric data. The homoleptic compound In(SAr′)3 can be isolated as a yellow oil. This liquid precursor has been derivatized by the reversible formation of acetonitrile and tetrahydrofuran adducts. Although, the molecule exists as a monomer in both adducts, the coordination number of the metal and he orientation of the ligands are markedly different. The internally chelating In(SAr″)3 and In(SAr.″′)3 adopt contrasting dimeric and monomeric structures respectively.

Erbium Tris(Amide) Compounds as Source Molecules FOR Rare Earth Doping of Semiconducting Materials

ABSTRACTThe homoleptic compound erbium{tris[bis (trimethylsilyl)]amide} displays high doping ability for incorporation of the rare earth element into epitaxially grown semiconducting host materials for fabrication of temperature-independent, monochromatic solid state optoelectronic devices. Electronic characteristics derived from erbium doped semiconducting films have been obtained. Several more volatile and lower melting representatives of this class of compounds have been synthesized, characterized by various analytical techniques and examined for their suitability to incorporate optically-active erbium centers into a semiconducting environment.

Organotin-substituted organosiloxanes: Synthesis and characterisation, including the crystal structure of 1,3-bis(triphenylstannoxy)-1,1,3,3-tetraphenyl-1,3-disiloxane

A series of linear 1,3-bis(triorganostannoxy)siloxanes (R′ 3SnO)R 2SiOSiR 2(OSnR′ 3) (R  Me, Ph; R′  Ph, nBu, c-C 6H 11) has been synthesised, and the compounds characterised by NMR ( 1H, 13C, 29Si and 119 Sn) and Mössbauer spectroscopies. The structure of the homoleptic compound R  R′ Ph has been determined by an X-ray diffraction study.

Schwingungsspektren und Normalkoordinatenanalyse der heteroleptischen Halogenohexaborate B6XnY6-n 2-, n = 1-5; Χ ≠ Υ = Cl, Br, I / Vibrational Spectra and Normal Coordinate Analysis of the Heteroleptic Halogenohexaborates B6XnY6-n 2-, n = 1— 5; Χ ≠ Y = Cl, Br, I

Normal coordinate analyses for the 24 mixed halogenohexaborates B6XnY6-n 2-, n = 1—5, Χ ≠ Y = Cl, Br, I, including the pairs of geometric isomers for n = 2, 3, 4 have been performed, based on a general valence force field. Using the bond lengths and force constants for the homoleptic species B6X6 2-, which with respect to the B6 cage are weighted standardized, the calculated frequencies are in good agreement with observed IR and Raman bands. The boronhalogen stretching vibrations for symmetric molecular axes correspond with the Ra(IR) bands of the homoleptic compounds: ClB6Cl 327 (515), BrB6Br 207 (430), IB6I 152 (394) cm-1. As a characteristic feature the mixed halogeno clusters exhibit bands with nearly averaged frequencies from asymmetrical axes: ClB6Br 261 (487), ClB6I 227 (473), BrB6I 178 (409) cm-1. This complete vibrational coupling is confirmed by properly balanced potential energy distribution on BX and BY bonds. There is a slight influence of the different substituents on the internal modes of the B6 cage (pseudo-Oh), observed in the sequence A1g>T1u> Eg>T2g in the region 1220-740 cm-1. The bands are shifted about 100 cm-1 with increasing mass of halogen, broadened by boron isotopomers (max. 60 cm-1), and degenerate vibrations are split by lowered point and site symmetry up to 100 cm-1.

Synthesis and reactivity of manganese(II) dialkylamido complexes. Crystal and molecular structure of [Mn3(µ-NEt2)6-(µ-Cl)2{Li(thf)2}2]·C7H16(thf = tetrahydrofuran) and [Mn2(µ-NPri2)2(NPri2)2

By reaction of MnCl2 with LiNR2(R = Me, Et or Pri) the corresponding dialkylamido complexes were prepared. The compounds [Mn3(µ-NEt2)6(µ-Cl)2{Li(thf)2}2]1(thf = tetrahydrofuran), [Mn2(µ-NPri2)2-(NPri2)2]2 and [Mn2(NMe2)4(LiCl)]3 were isolated, and the molecular and crystal structures of 1 and 2 determined by single-crystal X-ray diffraction methods. Crystal data: 1, monoclinic, space group C2/c, a= 18.81(1), b= 20.45(2), c= 18.15(2), Å, β= 113.31(8)°, R= 0.063; 2, monoclinic, space group P2/1c, a= 9.361(2), b= 9.724(2), c= 16.883(2)Å, β= 100.91(1)°, R= 0.046. The pentanuclear compound 1 consists of a trinuclear Mn3(NEt2)6Cl2 core, built up by edge-sharing of the three co-ordination tetrahedra, which are connected by four bridging diethylamido ligands, and terminally bonded to the Li(thf)2 moieties via chloride and amido bridges. The homoleptic compound 2 contains two three-co-ordinated manganese atoms, joined by two bridging dialkylamido groups, with an overall planar arrangement of the Mn2N4 skeleton. Both 1 and 2 react with CO2 to give the expected dialkylcarbamato complexes. The reactions of 1–3 with CO result in reductive carbonylation to [Mn(CO)5]–. The compounds also catalyse the selective carbonylation of secondary amines to dialkylformamides, a 87% yield of Et2NC(O)H being obtained from NHEt2 and CO at atmospheric pressure, in 24 h, in the presence of 1, at room temperature.

ChemInform Abstract: Soluble Polychalcogenides of the Late Transition and Main Group Elements

A review of the coordination chemistry of heavier polychalcogenide ligands with late transition and main group metals with a focus on recent developments in the author's laboratory is given. The complexes available thus far are mainly homoleptic anionic compounds of the general formula [M(Q x ) m ] n− (x≥2, Q=Se,Te), (M=late transition or main group metal) stabilized by large organic counterions. In most cases it was found that the structural types accessible by the heavier polychalcogenides are different from those of corresponding polysulfides

Characterisation of monomeric methylsodium and methylpotassium: infrared spectra of the matrix-isolated molecules

Co-condensation of CH3l with sodium or potassium vapour and an excess of N2 at ca. 20 K gives rise to the respective methylmetal monomer CH3Na or CH3K which is trapped in the resulting matrix. The i.r. spectrum of the matrix in the region 200–4 000 cm–1 discloses all six vibrational fundamentals characterising each of these molecules in C3v symmetry, the assignments being verified by measurements taking in the fully deuteriated as well as the undeuteriated isotopomer. How closely the molecules approximate to the formulation of CH3–M+(M = Na or K) is revealed through fundamentals which are lower in energy than those of any other homoleptic methylmetal compound reported to date. Normal co-ordinate analysis underlines this aspect with M–C stretching force constants =ca. 48 N m–1 and CH3 rocking force constants = 10.3 (M = Na) and 7.6 N m rad–2(M = K) which set new standards by their diminutive values.

Imido analogues of the tungstate(VI) and perrhenate(VII) ions. X-Ray crystal structures of Li2W(NBut)4 and Li(tmed)Re(NBut)4

The first homoleptic imido compounds of transition metals, namely the imido analogues of the tungstate, WO42–, and perrhenate, ReO4–, anions have been obtained as the lithium salts, Li2W(NBut)4and Li(tmed)Re(NBut)4; the structure of the tungsten compound contains two W(NBut)4 units linked by N ⋯ Li ⋯ N bridges while that of the rhenium compound shows the lithium co-ordinated to N atoms of tetramethylethylenediamine and to two N atoms of the anion.