Interesting π- and σ-bond hyperconjugations cause the unusual stability of the puckered Arduengo type divalents with electron deficient boron atoms.

The present study describes a simple and highly selective method for separation, preconcentration and spectrophotometric determination of extremely low concentrations of lead. It is based on flotation of a complex of Pb2+ ions and Alizarin yellow between aqueous and n-hexane interface at pH = 6. The proposed procedure is also applied for determination of lead in both tap water and prepared sea water samples. Beer's Law was obeyed over the concentration range of 3.86 × 10-8 To 8.20 × 10-7 molL-1 (8-170 ngmL-1) with an apparent molar absorptivity of 1.33 × 106 molL-1 cm-1 for a 100 mL aliquot of the water sample. The detection limit (n = 10) was 8.7 × 10-9 molL-1 (1.0 ngmL-1) and the Relative standard deviation (R.S.D), (n = 10) for 7.2 × 10-7 molL-1 (150 ngmL-1) of Pb (II) was 4.36%. A notable advantage of the method is that the determination of Pb (II) is free from the interference of almost all cations and ions found in the environment and waste water samples. The determination of Pb (II) in tap and synthetic seawater samples was also carried out by the present method. The results were satisfactorily comparable so that the applicability of the proposed method was confirmed to the real samples.

The present study describes a simple and highly selective method for separation, preconcentration and spectrophotometric determination of extremely low concentrations of lead. It is based on flotation of a complex of Pb2+ ions and Alizarin yellow between aqueous and n-hexane interface at pH = 6. The proposed procedure is also applied for determination of lead in both tap water and prepared sea water samples. Beer’s Law was obeyed over the concentration range of 3.86 × 10–8 To 8.20 × 10–7 molL−1 (8–170 ngmL−1) with an apparent molar absorptivity of 1.33 × 106 molL−1 cm−1 for a 100 mL aliquot of the water sample. The detection limit (n = 10) was 8.7 × 10–9 molL−1 (1.0 ngmL−1) and the Relative standard deviation (R.S.D), (n = 10) for 7.2 × 10–7 molL−1 (150 ngmL−1) of Pb (II) was 4.36%. A notable advantage of the method is that the determination of Pb (II) is free from the interference of almost all cations and ions found in the environment and waste water samples. The determination of Pb (II) in tap and synthetic seawater samples was also carried out by the present method. The results were satisfactorily comparable so that the applicability of the proposed method was confirmed to the real samples.

Molecular structures of [PCl2N]3-MCl3adducts, M=B, Al, Ga, In, Tl, have been studied employing HF, B3LYP*, B3LYP , PW91, BLYP, OLYP, BP and LDA methods using DZP basis set (as defined in Amsterdam Density Functional, ADF, package). Some aspects of adduct formation like considering the difference between Front and Back dihedral angles and also ring puckering showed that the [PCl2N]3-AlCl3is the most stable adduct comparing the others. Based on the comparison between the X-ray and theoretical geometrical parameters of [NPCl2]3(AlCl3) and [NPCl2]3(GaCl3), the LDA method and BP, PW91 and OLYP functionals combined with DZP basis set were found to yield the most satisfactory agreement. Results showed that with surprise, the LDA(DZP) method has the maximum matching with experimental data, comparing the others.

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