Preparation, characterisation and reactivity of a series of classical and non-classical rhenium hydride complexes ‡

Preparation and Reactivity of Hydrazine Complexes of Rhenium: Synthesis of 1,2‐Diazene (NH=NH) and Methyleneimine (CH2=NH) Derivatives

“…These two carbonyls are also magnetically equivalent, since the 13 C NMR spectrum shows only one multiplet at δ ϭ 194.7 ppm for the carbonyl carbon atoms. A singlet at δ ϭ 67.8 ppm is also present in the 13 protons, in agreement with the proposed assignment. In the temperature range between ϩ20 and Ϫ80°C the 31 P NMR spectrum appears as an A 2 B multiplet indicating that two of the phosphites are magnetically equivalent and different from the third.…”

“…A similar fac geometry can also be proposed for the methyldiazene derivative 10b on the basis of the presence of two ν(CO) bands in the IR spectrum and only one multiplet for the carbonyl carbon atoms at δ ϭ 196.2 ppm in the 13 C NMR spectrum, indicating the magnetic equivalence of the two cis carbonyl ligands. A singlet at δ ϭ 71.7 ppm is also present in the 13 C NMR spectrum; it was attributed, with the help of an HMQC experiment, to the methyl carbon atom of the CH 3 NϭNH ligand.…”

“…[13] [Re(NH 2 NH 2 )(CO){P(OEt) 3 } 4 ]BPh 4 (1a) and [Re{(CH 3 ) 2 NNH 2 } (CO){P(OEt) 3 } 4 ]BPh 4 (1e): An equimolar amount of CF 3 SO 3 H (0.2 mmol, 18 µL) was added to a solution of the hydride [ReH(CO){P(OEt) 3 } 4 ] (0.2 mmol, 196 mg) in 8 mL of CH 2 Cl 2 cooled to Ϫ196°C, and the reaction mixture warmed to room temperature and stirred for about 1 h. An excess of the appropriate hydrazine (0.6 mmol) was added to the resulting solution which was stirred for a time varying between 3 (1a) and 24 (1e) h and then the solvent was removed under reduced pressure. The oil obtained was triturated with 3 mL of ethanol containing an excess of NaBPh 4 (0.4 mmol, 137 mg).…”

“…Treatment of the hydrides [ReH(CO) n P 5Ϫn ] with the Brønsted acid CF 3 SO 3 H or HBF 4 (HY) gives the dihydrogen-containing cationic complexes [Re(η 2 -H 2 )(CO) n P 5Ϫn ] ϩ , [13] which are thermally unstable and easily lose H 2 yielding either the neutral ReY(CO) n P 5Ϫn species, containing the labile Y Ϫ ligand, or the coordinatively unsaturated [Re(CO) n P 5Ϫn ] ϩ cations. Reaction of these intermediates with an excess of hydrazine gives the final derivatives [Re(RNHNH 2 )(CO) n P 5Ϫn ] ϩ (1Ϫ8), which were isolated as their BPh 4 Ϫ salts and characterised.…”

New Nitrosylrhenium Hydrides as Precursors of “Diazo” Complexes: Preparation of Hydrazine and Diazene Derivatives

“…[5] Less attention, however, has been devoted to hydrazine and diazene chemistry. A glance through the literature shows, in fact, that hydrazine or substituted hydrazine complexes are rather rare and include, apart from the pioneering work on [Re(NCO)(CO) 2 (NH 2 NH 2 )P 2 ] (P ϭ tertiary phosphane) ture of the hydrazine and the stoichiometry of the complexes, led to aryldiazene [ReH(C 6 (12,14,16) and [{Re(OR 1 )(NO)P 3 } 2 (µ-HN=NAr−ArN=NH)](BPh 4 ) 2 (13,15) [R 1 = CH 3 , C 2 H 5 ; P = PPh(OEt) 2 , P(OEt) 3 ; Ar = C 6 H 5 , 4-CH 3 C 6 H 4 ; Ar-Ar = 4,4Ј-C 6 H 4 -C 6 H 4 ] were also prepared by allowing hydrides [ReH 2 (NO)[PPh 2 (OEt)} 3 ] and [ReH(OR 1 )(NO)P 3 ] to react with mono-and bis-aryldiazonium cations. ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) complexes, [6] only two papers [7] on [ReCp*Me 3 -(NH 2 NH 2 )]CF 3 SO 3 (Cp* ϭ pentamethylcyclopentadienyl) and [Re(NH 2 NH 2 )(CO) 3 (PPh 3 ) 2 ]CF 3 SO 3 hydrazine derivatives, and another on the substituted hydrazine complex [ReCl 2 (PPh 3 ) 2 {NNC(O)Ph}{H 2 NNHC(S)Ph}].…”