Crystal structure, optical, magnetic, and photochemical properties of the complex pentakis(dimethyl sulfoxide) nitrosylchromium(2+) hexafluorophosphate

Anders Rørbæk Døssing, Anders Kadziola, Johannes Wied Dethlefsen

6 Citationer (Scopus)

Abstract

 

    The nitrosyl complex [Cr(dmso)5(NO)](PF6)2 (1) (dmso = dimethyl sulfoxide) has been prepared by the solvolysis of [Cr(NCCH3)5(NO)](PF6)2 in neat dmso. The compound 1 crystallizes in orthorhombic space group Pna21 with a = 11.3370(15), b = 24.0790(5), and c = 11.007(3) Å at 122 K with an almost linear Cr-N-O angle (176.45(13)°). The optical absorption spectrum of 1 in dmso shows maxima at 734, 567, 450, 413, and 337 nm. Continuous photolysis of 1 with l = 365 - 580 nm light in dmso solution results in a release of NO with quantum yield, F, in the range 0.034 - 0.108 mol×Einstein-1. Irradiation of a deoxygenated CH3CN solution of [Cr(NCCH3)5(NO)](PF6)2 in the presence of excess of [Fe(S2CNEt2)2] results in a transfer of NO to the iron centre as shown from the characteristic EPR spectrum of [Fe(S2CNEt2)2(NO)] with Aiso(14N) = 12.2´10-4 cm-1. The EPR parameters of 1 were determined: giso, g¦ and g-: 1.96725, 1.91881(4) and 1.992763(2); Aiso(53Cr), A¦(53Cr) and A-(53Cr): 22.8´10-4, 39´10-4 and 15.8´10-4cm-1; Aiso(14N), A¦(14N) and A-(14N): 5.9´10-4, 2´10-4 and 7.540(4)´10-4 cm-1. The pseudo-first-order rate constant, k, for the substitution of the dmso ligands in 1 with dmso has been found by 1H NMR in dmso-d6 solution in the temperature range 293 - 308 K to be k = (8.95 ± 0.09) ´10-4 s-1 (t½ = 12.9 ± 0.1 min) at 298 K with DH = 100(2) kJ×mol-1 and DS = 32(5) J×mol-1×K-1.


Udgivelsesdato: April
OriginalsprogEngelsk
TidsskriftInorganica Chimica Acta
Vol/bind362
Udgave nummer5
Sider (fra-til)1585-1590
Antal sider6
ISSN0020-1693
StatusUdgivet - 2009

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