Preparation and Reactivity of Mixed-Ligand Ruthenium(II) Hydride Complexes with Phosphites and Polypyridyls

Chloro complexes [RuCl(N-N)P 3 ]BPh 4 ( 1 − 3 ) [N-N = 2,2‘-bipyridine, bpy; 1,10-phenanthroline, phen; 5,5‘-dimethyl-2,2‘-bipyridine, 5,5‘-Me 2 bpy; P = P(OEt) 3, PPh(OEt) 2 and PPh 2 OEt] were prepared by allowing the [RuCl 4 (N-N)]·H 2 O compounds to react with an excess of phosphite in ethanol. The bis(bipyridine) [RuCl(bpy) 2 {P(OEt) 3 }]BPh 4 ( 7 ) complex was also prepared by reacting RuCl 2 (bpy) 2 ·2H 2 O with phosphite and ethanol. Treatment of the chloro complexes 1 − 3 and 7 with NaBH 4 yielded the hydride [RuH(N-N)P 3 ]BPh 4 ( 4 − 6 ) and [RuH(bpy) 2 P]BPh 4 ( 8 ) derivatives, which were characterized spectroscopically and by the X-ray crystal structure determination of [RuH(bpy){P(OEt) 3 } 3 ]BPh 4 ( 4a ). Protonation reaction of the new hydrides with Brønsted acid was studied and led to dicationic [Ru(η 2 -H 2 )(N-N)P 3 ] 2+ ( 9, 10 ) and [Ru(η 2 -H 2 )(bpy) 2 P] 2+ ( 11 ) dihydrogen derivatives. The presence of the η 2 -H 2 ligand was indicated by a short T 1min value and by the measurements of the J HD in the [Ru](η 2 -HD) isotopomers. From T 1min and J HD values the H−H distances of the dihydrogen complexes were also calculated. A series of ruthenium complexes, [RuL(N-N)P 3 ](BPh 4 ) 2 and [RuL(bpy) 2 P](BPh 4 ) 2 (P = P(OEt) 3; L = H 2 O, CO, 4-CH 3 C 6 H 4 NC, CH 3 CN, 4-CH 3 C 6 H 4 CN, PPh(OEt) 2 ], was prepared by substituting the labile η 2 -H 2 ligand in the 9, 10, 11 derivatives. The reactions of the new hydrides 4 − 6 and 8 with both mono- and bis(aryldiazonium) cations were studied and led to aryldiazene [Ru(C 6 H 5 N NH)(N-N)P 3 ](BPh 4 ) 2 ( 19, 21 ), [{Ru(N-N)P 3 } 2 (μ-4,4‘-NH NC 6 H 4 −C 6 H 4 N NH)](BPh 4 ) 4 ( 20 ), and [Ru(C 6 H 5 N NH)(bpy) 2 P](BPh 4 ) 2 ( 22 ) derivatives. Also the heteroallenes CO 2 and CS 2 reacted with [RuH(bpy) 2 P]BPh 4, yielding the formato [Ru{η 1 -OC(H) O}(bpy) 2 P]BPh 4 and dithioformato [Ru{η 1 -SC(H) S}(bpy) 2 P]BPh 4 derivatives.