Reaction of [L_OEtRu(N)CI₂] (1) (L_OEt^- = [CpCo{P(O)(OEt)₂}₃]^- , where Cp = η⁵-C₅H₅) with Et₃SiH, 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (pinacolborane) or ⁿBu₃SnH afforded the Ru(III) ammine complex [L_OEtRu(NH₃)CI₂] (2). Treatment of 1 with [L_OEtRuH(CO)(PPh₃)] (3) afforded a dinuclear Ru(IV)/Ru(II) μ-imido complex [L_OEtRuCI₂(μ-NH)Ru(CO)(PPh₃)L_OEt] (4). The reaction between 1 and 3 in toluene was found to follow the rate law: rate = k₂[1][3]. At 298 K, k₂ was determined to be (7.2 ± 0.4) × 10^-5 M^-1⋅s^-1. The activation parameters ΔH^‡ and ΔS^‡ were found to be (8.8 ± 1.6) kcal⋅mol^-1 and -(43.3 ± 11.1) e.u., suggesting that the formation of 4 involved a concerted pathway of the nucleophilic attack of the nitride by the Ru^II hydride. Reaction of 1 with 5 atm H₂ in the presence of 6 and Et₃N...[ Read more ]

Reaction of [L_OEtRu(N)CI₂] (1) (L_OEt^- = [CpCo{P(O)(OEt)₂}₃]^- , where Cp = η⁵-C₅H₅) with Et₃SiH, 4,4,5,5-tetramethyl-1,3,2-dioxaborolane (pinacolborane) or ⁿBu₃SnH afforded the Ru(III) ammine complex [L_OEtRu(NH₃)CI₂] (2). Treatment of 1 with [L_OEtRuH(CO)(PPh₃)] (3) afforded a dinuclear Ru(IV)/Ru(II) μ-imido complex [L_OEtRuCI₂(μ-NH)Ru(CO)(PPh₃)L_OEt] (4). The reaction between 1 and 3 in toluene was found to follow the rate law: rate = k₂[1][3]. At 298 K, k₂ was determined to be (7.2 ± 0.4) × 10^-5 M^-1⋅s^-1. The activation parameters ΔH^‡ and ΔS^‡ were found to be (8.8 ± 1.6) kcal⋅mol^-1 and -(43.3 ± 11.1) e.u., suggesting that the formation of 4 involved a concerted pathway of the nucleophilic attack of the nitride by the Ru^II hydride. Reaction of 1 with 5 atm H₂ in the presence of 6 and Et₃N afforded 4 and [L_OEtRu(OH)(CO)(PPh₃)][BF₄] in 10 and 15 % yield, respectively.

Reaction of 1 with [(PCy₃)₂RuHCl(CO)] gave the dinuclear μ-nitrido complex [L_OEtRuCl₂(μ-N)RuHCl(CO)(PCy₃)₂] (8) (Cy = cyclohexyl). A X-ray diffraction study suggested that 8 should be formulated as a Ru^VI≡N–Ru^II complex.

Refluxing 1 in CCl₄ afforded the mixed valence Ru(IV)/Ru(V) μ-nitrido complex [L_OEtRuCl₂]₂(μ-N) (9), presumably via the N ⋅ ⋅ N coupling of Ru(VI) nitride and subsequent coupling of the Ru(III) intermediate with the Ru(VI) nitride. Reduction of 9 in air gave the Ru(IV)/Ru(IV) complex [H(H₂O)₃][L_OEtRuCl₂]₂(μ-N) (10) that contains a symmetrical Ru^IV=N=Ru^IV bridge. 10 exhibited reversible Ru(IV,V)/Ru(IV,IV) and Ru(V,V)/Ru(IV,V) couples at 0.186 V and 1.132 V vs Cp₂Fe^+/0, respectively.

Homo- and heterobimetallic Ru μ-nitrido complexes have been synthesized by reaction of Ru(VI) nitrides with low valent organometallic complexes. Heating 1 with [Ru(p-cymene)Cl₂]₂ in benzene afforded a tetranuclear Ru(IV) μ-nitrido cluster [L_OEtRuCl₂(μ-N)RuCl₂(H₂O)]₂ (12) that contains a symmetrical Ru^IV=N=Ru^IV bridge. Reaction of [Ru(ppy)(MeCN)₄][PF₆] (Hppy = 2-phenylpyridine) with 1 afforded [L_OEtRuCl₂(μ-N)Ru(ppy)(MeCN)₃][PF₆] (13). Reaction of [Ru(ppy)(MeCN)₄][PF₆] with mer-[Ru(N)Cl₃(AsPh₃)₂] and [Ru(N)Cl₄]^- afforded [RuCl₃(AsPh₃)₂(μ-N)-Ru(ppy)(MeCN)₃][PF₆] (14) and [RuCl₄(μ-N)Ru(ppy)(MeCN)₃] (15), respectively.

Reaction of 14 with AgOTf (OTf^- = triflate) afforded [RuCl₂(AsPh₃)(H₂O)(μ-N) Ru(ppy)(MeCN)₃][PF₆][OTf] (16). Substitution of 14 with K[N(Ph₂PQ)₂] (Q = S, O) led to formation of [Ru{N(Ph₂PS)₂}₂Cl(μ-N)Ru(ppy)(MeCN)₃][PF₆] (17) and [Ru{N(Ph₂PO)₂}Cl₂(AsPh₃)(μ-N)Ru(ppy)(MeCN)₃][PF₆] (18), respectively. Treatment of 1 with [M(COD)Cl]₂ (M = Ir, Rh COD = 1,5-cyclooctadiene) afforded Ru(VI)/M(I) heterobimetallic μ-nitrido complexes [L_OEtRuCl₂(μ-N)M(COD)Cl] (M = Ir (19), Rh (20)). Treatment of 1 with [Cp*IrCl₂]₂ (Cp* = η⁵-C₅Me₅), [Cp*Ir(ppy)(H₂O)][OTf] and [Ir(ppy)₂Cl]₂ afforded the Ru(VI)/Ir(III) μ-nitrido complexes [L_OEtRuCl₂(μ-N)IrCp*Cl₂] (21), [L_OEtRuCl₂(μ-N)IrCp*(ppy)][OTf] (22) and [L_OEtRuCl₂(μ-N)Ir(ppy)₂Cl] (23), respectively. X-ray diffraction studies revealed that complexes 13-20 are unsymmetrical μ-nitrido complexes containing the Ru^VI≡N–M’ bridges.

Treatment of [ⁿBu₄N][Ru(N)Cl₄] with K[N(R₂PS)₂] in tetrahydrofuran at -78℃ afforded the Ru(IV)/Ru(IV) bimetallic μ-nitrido complexes trans-[Ru₂{N(R₂PS)₂}₄Cl(μ-N)] (R = Ph (24), Prⁱ(25)). Reaction of [ⁿBu₄N][Ru(N)Cl₄] with K[N(^tBu₂PS)₂] gave the Ru(II) thionitrosyl complex trans-[Ru(NS){N(^tBu₂PS)}₂Cl] (26), presumably via abstraction of the sulfur in [N(^tBu₂PS)₂]^- by a Ru(VI) nitride intermediate. Trans-[Ru(NS){N(R₂PS)}₂Cl] (R = Ph (29), Prⁱ (30), ^tBu (26)) could be conveniently prepared from mer-[Ru(NS)Cl(AsPh₃)₂] and K[N(R₂PS)₂]. Treatment of [Ru(PPh₃){N(Ph₂PS)₂}₂] with PhN₃ afforded [Ru{N(PhN)}₂{N(Ph₂PS)₂}₂] (32) containing a neutral tetrazene ligand, presumably via the [2+3] cycloadditon of a Ru(IV)=NPh intermediate with PhN₃.

A cationic Ru(VI) nitride complex containing a bulky bidentate Schiff base ligand, trans-[Ru(N)(H₂O)L₂][OTf] (34), was prepared from cis-[Ru(N)Cl(L)₂] (33) (HL = 2-[(2,6-diisopropylphenyl)imino]methyl-4,6-dibromophenol) and AgOTf. No N ⋅ ⋅ N coupling was found when 34 was reacted with pyridine in polar solvents. Treatment of 33 with Me₃NO and elemental sulfur gave cis-[Ru(NO)Cl(L)₂] (35) and cis-[Ru(NS)Cl(L)₂] (36), respectively. Irradiation of cis-[Ru(NO)Cl(L)₂] in CH₂Cl₂/MeCN with UV ligand afforded [Ru(MeCN)Cl(L)₂] (37) that could also be prepared by treatment of 33 with Me₃SiN₃.

Refluxing FeCl₂ with HL in methanol in the presence of Et₃N afforded [Fe(OMe)(L)₂] (38). Reaction of [Fe(OMe)(L)₂] with HCl and Me₃SiN₃ gave [FeCl(L)₂] (39) and [Fe(N₃)L₂] (40), respectively.