Band 35, Heft 5-6

This review covers 90 heterodimeric Pt complexes with non-transition metals. There are 13 non-transition metals (Ge, Sn, Pb, Ga, In, Tl, Sb, Zn, Cd, Hg, Na, K and Ca). These dimers can be divided into three groups, the first in which only a direct Pt-M bond connects respective units (59%); the second in which in additon to a direct Pt-M bond a ligand/s serves as bridge/s (33%); and the third one in which two respective units are held together via bridge/s ligand/s. The mean Pt-M bond distance elongates in the sequence: 2.425 Å (M=Ge) <2.559 Å (Sb) <2.601 Å (In) <2.625 Å (Cd) <2.657 Å (Hg) <2.663 Å (Sn) <2.670 Å (Pb) <2.674 Å (Tl) <2.760 Å (Zn) <2.960 Å (Ca). The Pt atom has oxidation numbers 0, +2 (most common) and +4, and the M atoms have +1, +2 (most common), +3 and +4. The Pt coordination geometrics include square planar (most common), trigonal bi­pyramidal, pseudo-octahedral Pt(IV). There are examples which contain two independent dimers (distortion isomers). Factors affecting bond distances and angles are discussed and some ambiguities in coordination poly­hedra are outlined.

Phosphine compounds [2,6-( t BuOCH 2 ) 2 C 6 H 3 ]PPh 2 ( 1 ) and [2,6-(Me 2 NCH 2 ) 2 C 6 H 3 ]PPh 2 ( 2 ) containing Y,C,Y-chelating ligands were treated with BH 3 ‧SMe 2 . Coordination of BH 3 ·SMe 2 by 2 produced complex {[2,6-(Me 2 NCH 2 ) 2 C 6 H 3 ]Ph 2 P}‧(BH 3 ) 3 ( 3 ). Compound 3 was characterized by means of elemental analyses, 1 H, 11 B, 13 C, 31 P NMR spectroscopy, and by single crystal X-ray diffraction analysis.

The synthesis of [Bi(C 18 H 14 P(O)SO 3 ) 2 (DMSO) 3 ](NO 3 )∙DMSO∙2H 2 O starting from [Bi 6 O 4 (OH) 4 ](NO 3 ) 6 ∙H 2 O and 2-(diphenylphosphino)benzenesulfonic acid is presented. 31 P{ 1 H}-NMR experiments confirm the in situ oxidation of 2-(diphenylphosphino)benzenesulfonic acid to give 2-(diphenylphosphine oxide)benzenesulfonic acid by heating in dimethyl sulfoxide (DMSO). In the presence of [Bi 6 O 4 (OH) 4 ](NO 3 ) 6 ∙H 2 O, subsequent formation of single crystals of the title compound is observed. The crystal structure determination reveals that the bismuth atom shows a [5+4] coordination with short Bi–O distances in the range of 2.278(11) to 2.398(11) Å to the oxygen atoms of DMSO and phosphine oxide groups and with longer Bi–O bonds of 2.74(2) and 2.88(2) Å to the chelating sulfonate groups.

Methyl and phenyl germanium chlorides (R n GeCl 4-n , n=1, 2, 3), just like GeCl 4 , form complexes with electroactive bidentate (2,2'-bipyridine) and monodentate (imidazole, pyrimidine and 2,6-dichloro-pyridine) ligands, R n GeCl 4-n ‧L x (x=1 or 2 for bi- and monodentate Ls, respectively), which were studied by cyclic voltammetry and electron paramagnetic resonance (EPR) spectroscopy supported by density functional theory (DFT) calculations. Dative interactions of lone pair of N of these heteroaromatic ligands towards Ge lower the reduction potential E p of such complexes by about 1 V compared to own reduction potential E o of L. Electron transfer to these complexes is reversible, resulting in corresponding anion radicals. Elimination of Cl - anion from these species leads to L-coordinated radicals whose one-electron reduction is also reversible. Real-time, time-dependent EPR spectro­electrochemistry of electrogenerated anion radicals of complexes with 2,2'-bipyridine (bipy) has shown that spin in these species is delocalized on the bipy moiety; nitrogen hfc constants suggest that two N atoms are non-equivalent and occupy different positions in the Ge environment. These findings are supported by DFT calculations.

The structures of the Group 1 metal aminoalkoxides Li[OCH(CH 2 CNMe 2 ) 2 ] ( 1 ) and K[OCH(CH 2 CNMe 2 ) 2 ]∙HOCH(CH 2 CNMe 2 ) 2 ( 2 ) have been determined. 1 is a hexa­meric drum in which two Li 3 O 3 rings are joined co-facially, whereas 2 is tetrameric and adopts a K 4 O 4 ladder structure, novel for homoleptic potassium alkoxides.

Quantum-chemical calculations at the RHF/6-31G(d) and MP2/6-31G(d) levels of two stable structures of 1,3-diphenyl-3-methyl-3-(trichlorogermyl)butanone-1 mol­ecule were executed. According to calculations at the RHF/6-31G(d) level, the structure with pentacoordinated Ge atom is by 7.49 kJ/mol energetically more advantageous as compared with that with the tetracoordinated one. Using 3 p -components of the Cl atom valence p -orbitals obtained from these calculations, the 35 Cl nuclear quadrupole resonance (NQR) parameters of this compound with the pentacoordinated Ge atom were assessed. Calculations performed at both the RHF/6-31G(d) and MP2/6-31G(d) levels do not differ principally and are close to experimental NQR data. Calculations at the RHF/6-31G(d) level performed at various Ge‧‧‧O distances demonstrated that convergence of the Ge and O coordination centers leads to an increase in the positive charge at the Ge atom and in the negative charge at the O atom, and with that, electron density from the Ge atom shifts mainly to the axial Cl atom and from the C atom of carbonyl group to its O atom. On such convergence, the electron density of atoms directly bonded to those of the Ge coordination polyhedron decreases to some extent.

Two methods are described for the determination of stability constants of adrenaline with metal ions. In method A, the solution equilibria of Al(III) complex formed with bidentate ligand of adrenaline in acidic media at pH ranges of ≈3 to ≈5 have been studied in cosolvent systems at 15, 20, 25±0.1°C and I =0.2 mol.dm -3 sodium chloride, employed phosphate buffer, with spectrophotometric methods. Evidence for the 2:1 complex was not observed for aluminum. The stability constants of the complex was determined and the resulting free-energy changes were obtained. The protonation constants of adrenaline were determined under the above condition. The results are discussed in terms of the effect of solvent on protonation and complexation. In method B, the complexation reaction with Fe(III) ions has been studied in water in 15, 20, 25±0.1°C. The stoichiometry of the complex was found to be 1:2 (metal ion/ligand). The stoichiometry of Fe(III)-adrenaline was estimated by mole ratio and continuous variation methods and emphasized by the KINFIT program. The values of the thermodynamic parameters for complexation reaction was obtained from the temperature dependence of the stability constants.

Lead sulfide (PbS) nanoparticles were synthesized at room temperature via a simple chemical reaction. In this work, thiophenol was used as the capping agent and sodium sulfide was used as a sulfur source. The products were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible, photoluminescence and Fourier transform infrared spectroscopy. Electron microscopy studies reveal that synthesis of PbS nanoparticles using no capping agent produces PbS nanoparticles with relatively large size, whereas adding thiophenol leads to the production of nano-sized PbS particles. We found that electronic absorption spectra as well as particle sizes depend on the used capping agents. Compared with bulk PbS, the absorption spectra of the obtained PbS nanoparticles exhibit a blue shift, which can be attributed to the quantum confinement of charge carriers in the nanoparticles.

The title compound (Cp*Sn)BPh 4 was obtained by the metathesis reaction of Cp*SnCl with NaBPh 4 and ­characterized by single crystal X-ray diffraction as well as solution and solid-state 119 Sn nuclear magnetic resonance (NMR) spectroscopy. The coordination modes are best described as (η 5 -C 5 Me 5 )Sn(μ-η 6 -Ph) 2 BPh 2 .

The crystal structure of the previously known title compound, Ph 3 SnO 3 SCF 3 , was determined by single-crystal X-ray diffraction; it comprises a one-dimensional polymeric structure and pentacoordinated Sn atoms.

The molecular of the title compound n -Bu 3 PTe was established by X-ray crystallography and compared with the previously known trialkylphosphine tellurides.