Majid Motevalli

Synthesis and chemistry of the bis(trimethylsilyl)amido bis-tetrahydrofuranates of the group 2 metals magnesium, calcium, strontium and barium. X-ray crystal structures of Mg[N(SiMe3)2]2·2THF and related Mn[N(SiMe3)2]2·2THF

Abstract Transamination reactions utilizing the compound mercuric bis(trimethylsilyl)amide, Hg{N(SiMe3)2}2, in tetrahydrofuran (THF), and the metals Na, Mg, Ca, Sr, Ba and Al have been investigated. Thus the THF solvated compounds Na[N(SiMe3)2]·THF and M[N(SiMe3)2]2·2THF, M = Mg, Ca, Sr and Ba (1–4), have been prepared. The X-ray crystal structures of 1 and the related manganese compound Mn[N(SiMe3)2]2·2THF (5) are reported. Interaction of the silylamides, 2–4, with a range of crown ethers apparently proceeded with elimination of silylamine, (Me3Si)2NH, and novel ring opening of the crown ethers, generating species containing a donor alkoxide ligand with a vinyl ether function, presumably, O(CH2CH2O)nCHCH2 (n = 3−5). The silylamides 2–4 were also cleanly converted to the corresponding alkoxides (from 1H NMR data) in reactions with stoichiometric quantities of 3-ethyl-3-pentanol.

Synthesis of PbS nanocrystallites using a novel single molecule precursors approach : X-ray single-crystal structure of Pb(S2CNEtPri)2

The synthesis and characterisation of some lead(ii) dithiocarbamato complexes Pb(S 2 CNRR′) 2 is reported. These compounds were used as single molecule precursors to produce nanocrystalline PbS by their thermolysis in trioctylphosphine oxide. The optical and morphological properties of the resulting PbS nanocrystallites were investigated; the influence of experimental parameters, such as precursor, growth time and temperature, on the final nanodispersed materials is also reported.

Quenching of Er(III) luminescence by ligand C–H vibrations: Implications for the use of erbium complexes in telecommunications

The authors have quantified the quenching of the luminescence lifetime of Er3+ ions in organic complexes due to the presence of CH vibrational oscillators as a function of their distance from the ion. They have shown that any hydrogen atoms within a sphere of at least 20A from an erbium ion will cause sufficient quenching to prohibit its use in telecommunications applications.

The crystal and molecular structure of N,N-diethyldiselenocarbamatocadmium(II): Cadmium and zinc diethyldiselenocarbamates as precursors for selenides

Abstract The X-ray crystal structure of N,N-diethyldiselenocarbamatocadmium(II) has been determined and contains centrosymmetric, dimeric molecular units Of [Cd2(Se2 CNEt2)4] with five-coordinated distorted square pyramidal cadmium. Preliminary studies of the pyrolysis of both cadmium and zinc diethyldiselenocarbamates show that these complexes may be useful precursors for the deposition of ZnSe and CdSe.

Volatile tris-tertiary-alkoxides of yttrium and lanthanum. The x-ray crystal structure of [La3(OBut)9(ButOH)2]

Abstract Tertiary alkoxides of yttrium and lanthanum have been prepared by addition of excess tertiary alcohol to the metal tris-(bis-trimethylsilylamides), M{N(SiMe3)2}3 (M = Y, La), and characterized by elemental analyses, NMR, IR and mass spectroscopy. With t-butanol and t-amyl alcohol the alcoholates [Y3(OBut)9(ButOH)2] (1), [Y3(OAmt)9 (AmtOH)2] (2) and [La3(OBut)9(ButOH)2] (3) were isolated. With higher tertiary alcohols the tris-t-alkoxides [M(OR)3] were obtained [M = Y, R = CMe2Pri (4), CMeEtPri (5), CEt3 (6); M = La, R = CMe2Pri (7), CMeEtPri (8)] as dimers. The coordinated ButOH in 1 could be replaced by THF or pyridine but not by trimethylamine. The X-ray crystal structure of 3 showed that the La3 triangle is capped by two μ3-OBut groups with three μ2-OBut bridges as in [La3(μ3-OBut)2(μ-OBut)3(OBut)4(ButOH)2]. The variable temperature NMR data suggest that compounds 1 and 2 have the same structure in solution as compound 3.

Reactions of tetra-µ-carboxylato-diruthenium(II,II) compounds. X-Ray crystal structures of Ru2(µ-O2CCF3)4(thf)2, Ru2(µ-O2CR)4(NO)2(R = Et or CF3), and {Na3[Ru2(µ-O2CO)4]·6H2O}n

Improved procedures for the synthesis of the diruthenium(II) carboxylates, Ru2(µ-O2CR)4L2, and substitutions of either the bridged carboxylate or axial ligands (L) are described. Among new bridged compounds are the trifluoroacetate, Ru2(µ-O2CCF3)4, the carbonate, {Na3[Ru2(µ-O2CO)4]·6H2O}n, and the triazenide, Ru2(µ-N3Ph2)4; adducts of the triazenide include the nitrosyl, Ru2(µ-N3Ph2)4(NO)2, the isocyanide, Ru2(µ-N3Ph2)4(ButNC), and the carbonyl Ru2(µ-N3Ph2)4(CO)2. Reactions of the carboxylates with donors such as isocyanides, pyridine (py), phosphines, or CO leads in some cases to bridge cleavage and products such as trans-Ru(O2CR)2(py)4 or Ru(O2CR)2(PPh3)2(R = Me or CF3), while the reactions with NO yield the diamagnetic adducts Ru2(µ-O2CR)4(NO)2. Infrared, n.m.r., e.s.r., and electronic spectra are recorded together with cyclic voltammetric studies. The X-ray crystal structures of the dimers Ru2(µ-O2CCF3)4(thf)2(thf = tetrahydrofuran) and Ru2(µ-O2CR)4(NO)2(R = Et or CF3), and the polymer {Na3[Ru2(µ-O2CO)4]·6H2O}n are reported.

The X-ray crystal structures of the cadmium complexes of pyridine-1-thiol and mercaptobenzothiazole, [cd(C5H4NS)2]n And [Cd(C7H4N2S2)2]n: Two unusual volatile polymeric complexes

Abstract The structures of the 2:1 complexes formed by pyridine-1-thiol (I) and mercaptobenzothiazole (II) with cadmium(II) are polymeric but both sublime at reduced pressure and decompose cleanly to CdS in air. Both structures contain approximately octahedrally-coordinated cadmium atoms (CdN2S4) and involve bridging and chelating modes for the ligand.

Synthesis and characterisation of some N-alkyl/aryl and N,N′-dialkyl/aryl thiourea cadmium(II) complexes: the single crystal X-ray structures of [CdCl2(CS(NH2)NHCH3)2]n and [CdCl2(CS(NH2)NHCH2CH3)2]

A series of cadmium(II) complexes with N -alkyl or aryl and N ,N ?-dialkyl or diaryl thioureas (RNHCSNHR?; where R � /R?� / CH3 ,C H 2CH3 ,C 6H5 and or R ?� /H) have been synthesised and characterised. The structures of the polymer [CdCl2(CS(NH2)NHCH3)2]n (I) and monomer [CdCl2(CS(NH2)NHCH2CH)2 ]( II) were determined by single crystal X-ray methods. The structure (I) is a polymer chain built from [CdCl3S3] distorted octahedra. Complex II is monomeric with a distorted tetrahedral geometry at the cadmium centre. 1 H NMR spectroscopy in deuterated dimethyl sulfoxide at room temperature had broadened NH peaks in the lower field (region 6.0 � /10.0 ppm) which indicates the presence of both cis and trans -isomers for the N alkylthioureas. All the spectroscopic data obtained are consistent with the coordination of ligands by sulphur atom to the metal ion. Thermogravimetric studies show that several of these complexes decompose cleanly to CdS and may be useful in materials preparation.

Deposition of CdSe thin films using a novel single-source precursor; [MeCd{(SePiPr2)2N}]2

The novel complex [MeCd{(SePiPr2)2N}]2 has been synthesised and its structure determined by X-ray single crystal methods. The compound is suitable for the deposition of cadmium selenide films by low pressure chemical vapour deposition.

Structural studies of some Group 12 metal alkyl adducts: the X-ray crystal structures of Me2Zn[Me2N(CH2)2NMe 2], Me2Cd[Me2N(CH2)2NMe2], (Me3CCH2)2Zn[Me2N(CH2)2NMe2] and (Me3CCH2)2Cd[Me2N(CH2)2NMe2]

Abstract The X-ray crystal structures of a series of group 12 metal alkyl adducts Me 2 M[Me 2 N(CH 2 ) 2 NMe 2 ] {M  Zn ( 1 ), Cd ( 2 )} and (Me 3 CCH 2 ) 2 M[Me 2 N(CH 2 ) 2 NMe 2 ] {M  Zn ( 3 ), Cd ( 4 )} have been determined. Each adduct exists as a mononuclear, molecular unit with pseudo-tetrahedral coordination at the metal centre. Compound 1 crystallizes in space group P 2 1 / a , a 13.868(3), b = 11.616(2) and c = 7.588(2) A, β = 94.83(2)°, compound 2 in space group Cmca , a = 11.196(2), b = 12.179(2) and c 17.969(3) A. Compounds 3 and 4 are isostructural in space group C 2 / c with the following unit cell dimensions for Zn {Cd}: a = 17.167(5) {17.604(5)}, b = 9.369(3) {9.484(3)}, and c = 12.916(3) {12.758(3)} A, β = 107.83(2) {106.07(2)}.° Compound 1 and the parent alkyl of 4 have been used successfully in the growth of thin films by metalloorganic chemical vapour deposition, 1 as a dopant in the growth of p-type GaAs, and [Me 3 CCH 2 ] 2 Cd as a Group 12 source in the growth of CdS.