caa a22 4500 469072083 CHVBK 20180323132924.0 cr unu---uuuuu 170328e19921201xx s 000 0 eng 10.1007/BF00672015 doi (NATIONALLICENCE)springer-10.1007/BF00672015 The nephelauxetic effect and ortho- to para-positronium conversion reactions promoted by Cr(III) complexes [Elektronische Daten] [Anna Fantola Lazzarini, Ennio Lazzarini] The ortho- (o-Ps) to para-positronium (p-Ps) conversion reactions promoted by ten Cr(III) complexes were investigated at several temperatures. The results obtained are discussed together with those of three other Cr(III) complexes measured previously. It was found that all the reactions studied are diffusion controlled and that their rate constants,k SE, increased as the corresponding ratiosB/B o between the Racah interelectronic repulsion parameters of Cr(III) complexes and Cr(III) gaseous ion decrease; that is,K SE increases as 3d electron cloud expansion promoted by ligands, increases. Therefore the o-Ps to p-Ps conversion reactions can be considered a complementary probe for the spectroscopic method in investigating the ligand capabilities to cause 3d cloud expansion. The effect is called ‘nephelauxetic' which means expanding (electron) cloud. Finally an empirical ‘average environmental rule', similar to that hypothesized for B/Bo ratios, is proposed for estimating the rate constants,K SE, of complexes formed with mixed ligand sets. Plenum Publishing Corporation, 1992 Fantola Lazzarini Anna Istituto di Ingegneria Nucleare-CeSNEF, Politecnico, Via Ponzio 34/3, 20133, Milano, Italy aut Lazzarini Ennio Istituto di Ingegneria Nucleare-CeSNEF, Politecnico, Via Ponzio 34/3, 20133, Milano, Italy aut Structural Chemistry Kluwer Academic Publishers 3/6(1992-12-01), 407-415 1040-0400 3:6<407 1992 3 11224 https://doi.org/10.1007/BF00672015 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00672015 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Fantola Lazzarini Anna Istituto di Ingegneria Nucleare-CeSNEF, Politecnico, Via Ponzio 34/3, 20133, Milano, Italy aut NATIONALLICENCE 700 1- Lazzarini Ennio Istituto di Ingegneria Nucleare-CeSNEF, Politecnico, Via Ponzio 34/3, 20133, Milano, Italy aut NATIONALLICENCE 773 0- Structural Chemistry Kluwer Academic Publishers 3/6(1992-12-01), 407-415 1040-0400 3:6<407 1992 3 11224 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer