ic302483e_si_002.pdf (339.73 kB)
Azo Complexes of Osmium(II): Preparation and Reactivity of Organic Azide and Hydrazine Derivatives
journal contribution
posted on 2013-03-18, 00:00 authored by Gabriele Albertin, Stefano Antoniutti, Laura Bonaldo, Alessandra Botter, Jesús CastroMixed-ligand
hydride complexes OsHCl(CO)(PPh3)2L (2) [L = P(OMe)3, P(OEt)3] were prepared by allowing
OsHCl(CO)(PPh3)3 (1) to react with
an excess of phosphite P(OR)3 in refluxing toluene. Dichloro
compounds OsCl2(CO)(PPh3)2L (3, 4) were also prepared by reacting 1, 2 with HCl. Treatment of hydrides OsHCl(CO)(PPh3)2L (2), first with triflic acid and
then with an excess of RN3 afforded organic azide complexes
[OsCl(η1-N3R)(CO)(PPh3)2L]BPh4 (5–7) [R
= 4-CH3C6H4CH2, C6H5CH2, C6H5; L
= P(OEt)3]. Benzylazide complexes react in CH2Cl2/ethanol solution, leading to the imine derivative
[OsCl(CO){η1-NHC(H)C6H4-4-CH3}(PPh3)2{P(OEt)3}]BPh4 (8b). Hydrazine complexes [OsCl(CO)(RNHNH2)(PPh3)2L]BPh4 (9–11) [R = H, CH3, C6H5; L = P(OMe)3, P(OEt)3] were prepared
by allowing hydride species OsHCl(CO)(PPh3)2L (2) to react first with triflic acid and then with
an excess of hydrazine. Aryldiazene derivatives [OsCl(CO)(ArNNH)(PPh3)2L]BPh4 (12, 13) were also prepared following two different methods: (i) by oxidizing
arylhydrazine [OsCl(C6H5NHNH2)(CO)(PPh3)2L]BPh4 (11) with Pb(OAc)4 in CH2Cl2 at −30 °C; (ii)
by allowing hydride species OsHCl(CO)(PPh3)2L (2) to react with aryldiazonium cations ArN2+ (Ar = C6H5, 4-CH3C6H4) in CH2Cl2. The complexes
were characterized spectroscopically and by X-ray crystal structure
determination of OsHCl(CO)(PPh3)2[P(OEt)3] (2b) and [OsCl{η1-NHC(H)C6H4-4-CH3}(CO)(PPh3)2{P(OEt)3}]BPh4 (8b).
