# Influence of the electronics of the phosphine ligands on the H-H bond elongation in dihydrogen complexes

Saikat, Dutta and Jagirdar, Balaji R and Nethaji, Munirathinam (2008) Influence of the electronics of the phosphine ligands on the H-H bond elongation in dihydrogen complexes. In: Inorganic Chemistry, 47 (2). 548 -557.

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## Abstract

Five new monocationic dihydrogen complexes of ruthenium of the type trans-$[RuCl(\eta^2-H_2)(PP)_2][BF_4]$ (PP = bis-1,2(diarylphosphino)ethane, aryl = p-fluorobenzyl, 1a, benzyl, 2a, m-methylbenzyl, 3a, p-methylbenzyl, 4a, p-isopropylbenzyl, 5a) have been prepared by protonating the precursor hydride complexes trans-$[RuCl(H)(PP)_2]$ using $HBF_4·OEt_2$. The dihydrogen complexes are quite stable and have been isolated in the solid state. The intact nature of the H-H bond in these derivatives has been established from the short spin-lattice relaxation times $(T_1, ms)$ and cobservation of substantial H, D couplings in the HD isotopomers. The H-H bond distances $(d_{HH}, \AA)$increase systematically from 0.97 to 1.03 \AA as the electron-donor ability of the substituent on the diphosphine ligand increases from the p-fluorobenzyl to the p-isopropylbenzyl moiety. The $d_{HH}$ in trans-$[Ru(\eta^2-H_2)(Cl)((C_6H_5-CH_2)_2PCH_2CH_2P(CH_2C_6H_5)_2)_2][BF_4]$, 2a,was found to be 1.08(5) \AA by X-ray crystallography. In addition, two new 16-electron dicationic dihydrogen complexes of the type $[Ru(\eta^2-H_2)(PP)_2]$ $[OTf]_2$ $(PP = (ArCH_2)_2PCH_2CH_2P(CH_2Ar)_2$, $Ar = m-CH_3C_6H_4-,6a, p-CH_3C_6H_4-, 7a)$ have also been prepared and characterized. These derivatives were found to possess elongated dihydrogen ligands.

Item Type: Journal Article This article copyright belongs to American Chemical Society Division of Chemical Sciences > Inorganic & Physical Chemistry 26 Feb 2008 19 Sep 2010 04:42 http://eprints.iisc.ernet.in/id/eprint/13091