Heterobimetallic Nitrido Complexes of Group 8 Metalloporphyrins.

Heterobimetallic nitrido porphyrin complexes with the [(L)(por)M-N-M'(LOEt)Cl2] formula {por2- = 5,10,15,20-tetraphenylporphyrin (TPP2-) or 5,10,15,20-tetra(p-tolyl)porphyrin (TTP2-) dianion; LOEt- = [Co(η5-C5H5){P(O)(OEt)2}3]-; M = Fe, Ru, or Os; M' = Ru or Os; L = H2O or pyridine} have been synthesized, and their electrochemistry has been studied. Treatment of trans-[Fe(TPP)(py)2] (py = pyridine) with Ru(VI) nitride [Ru(LOEt)(N)Cl2] (1) afforded Fe/Ru µ-nitrido complex [(py)(TPP)Fe(µ-N)Ru(LOEt)Cl2] (2). Similarly, Fe/Os analogue [(py)(TPP)Fe(µ-N)Os(LOEt)Cl2] (3) was obtained from trans-[Fe(TPP)(py)2] and [Os(LOEt)(N)Cl2]. However, no reaction was found between trans-[Fe(TPP)(py)2] and [Re(LOEt)(N)Cl(PPh3)]. Treatment of trans-[M(TPP)(CO)(EtOH)] with 1 afforded µ-nitrido complexes [(H2O)(TPP)M(µ-N)Ru(LOEt)Cl2] [M = Ru (4a) or Os (5)]. TTP analogue [(H2O)(TTP)Ru(µ-N)Ru(LOEt)Cl2] (4b) was prepared similarly from trans-[Ru(TTP)(CO)(EtOH)] and 1. Reaction of [(H2O)(por)M(µ-N)M(LOEt)Cl2] with pyridine gave adducts [(py)(por)M(µ-N)Ru(LOEt)Cl2] [por = TTP, and M = Ru (6); por = TPP, and M = Os (7)]. The diamagnetism and short (por)M-N(nitride) distances in 2 [Fe-N, 1.683(3) Å] and 4b [Ru-N, 1.743(3) Å] are indicative of the MIV═N═M'IV bonding description. The cyclic voltammograms of the Fe/Ru (2) and Ru/Ru (4b) complexes in CH2Cl2 displayed oxidation couples at approximately +0.29 and +0.35 V versus Fc+/0 (Fc = ferrocene) that are tentatively ascribed to the oxidation of the {LOEtRu} and {Ru(TTP)} moieties, respectively, whereas the Fe/Os (3) and Os/Ru (5) complexes exhibited Os-centered oxidation at approximately -0.06 and +0.05 V versus Fc+/0, respectively. The crystal structures of 2 and 4b have been determined.

Heterometallic cerium(IV) perrhenate, permanganate, and molybdate complexes supported by the imidodiphosphinate ligand [N(i-Pr2PO)2]-.

Heterometallic cerium(IV) perrhenate, permanganate, and molybdate complexes containing the imidodiphosphinate ligand [N(i-Pr2PO)2](-) have been synthesized, and their reactivity was investigated. Treatment of Ce[N(i-Pr2PO)2]3Cl (1) with AgMO4 (M = Re, Mn) afforded Ce[N(i-Pr2PO)2]3(ReO4) (2) or Ce2[N(i-Pr2PO)2]6(MnO4)2 (3). In the solid state, 3 is composed of a [Ce2{N(i-Pr2PO)2}6(MnO4)](+) moiety featuring a weak Ce-OMn interaction [Ce-OMn distance = 2.528(8) Å] and a noncoordinating MnO4(-) counteranion. While 3 is stable in the solid state and acetonitrile solution, it decomposes readily in other organic solvents, such as CH2Cl2. 3 can oxidize ethylbenzene to acetophenone at room temperature. Treatment of 1 with AgBF4, followed by reaction with [n-Bu4N]2[MoO4], afforded [Ce{N(i-Pr2PO)2}3]2(µ-MoO4) (4). Reaction of trans-Ce[N(i-Pr2PO)2]2(NO3)2 (5), which was prepared from (NH4)2Ce(NO3)6 and K[N(i-Pr2PO)2], with 2 equiv of [n-Bu4N][Cp*MoO3] yielded trans-Ce[N(i-Pr2PO)2]2(Cp*MoO3)2 (6). 4 can catalyze the oxidation of methyl phenyl sulfide with tert-butyl hydroperoxide with high selectivity. The crystal structures of complexes 3-6 have been determined.

Iridium porphyrin complexes with µ-nitrido, hydroxo, hydrosulfido and alkynyl ligands.

Iridium porphyrin complexes containing µ-nitrido, hydroxo, hydrosulfido, and alkynyl ligands have been synthesized and structurally characterized, and their oxidation has been studied. The alkyl-IrIII porphyrin complex [Ir(tpp)R] (tpp2- = 5,10,15,20-tetraphenylporphyrin dianion; R = C8H13; 1) was synthesized by reaction of [Ir(cod)Cl]2 (cod = 1,5-cyclooctadiene) with H2tpp in refluxing monoethylene glycol. Treatment of 1 with PPh3 and [(LOEt)Ru(N)Cl2] (LOEt- = [(η5-C5H5)Co{P(O)(OEt)2}3]-) gave [Ir(tpp)(R)(PPh3)] (2) and the µ-nitrido complex [R(tpp)Ir(µ-N)RuCl2(LOEt)] (3), respectively. The cyclic voltammogram of 3 exhibited a reversible oxidation couple at 0.44 V versus Fc+/0 (Fc = ferrocene). The oxidation of 3 with [(4-BrC6H4)3N](SbCl6) resulted in Ir-C bond homolysis and formation of the chloride complex [Cl(tpp)Ir(µ-N)RuCl2(LOEt)] (4). The short Ir-N(nitrido) bond distances in 3 [1.944(3) Å] and 4 [1.831(4) Å] are indicative of multiple bond character and thus these two µ-nitrido complexes can be described by the two resonance forms: IrIII-N[triple bond, length as m-dash]RuVI and IrV[double bond, length as m-dash]N[double bond, length as m-dash]RuIV. Similarly, the oxidation of 2 with [(4-BrC6H4)3N](SbCl6) yielded [Ir(tpp)Cl(PPh3)] (5). Chloride abstraction of 5 with TlPF6 in tetrahydrofuran (thf) afforded [Ir(tpp)(PPh3)(thf)](PF6) (6) that reacted with CsOH·H2O and Li2S to give the hydroxo [Ir(tpp)(OH)(PPh3)] (7) and hydrosulfido [Ir(tpp)(PPh3)(SH)] (8) complexes, respectively. Treatment of 6 with phenylacetylene in the presence of CuI and Et3N yielded the bimetallic complex [Ir(tpp)(PPh3)(µ-η1:η2-C[triple bond, length as m-dash]CPh)(CuI)] (9), whereas the transmetallation of 6 with LiC[triple bond, length as m-dash]CPh afforded the mononuclear alkynyl complex [Ir(tpp)(PPh3)(C[triple bond, length as m-dash]CPh)] (10). The electrochemistry of the Ir porphyrin complexes has been studied using cyclic voltammetry. On the basis of the measured redox potentials of [Ir(tpp)(PPh3)X], the ability of X- to stabilize the IrIV state is ranked in the order: R- > PhC[triple bond, length as m-dash]C- > Cl- ∼ OH-. Oxidation of 8 and 9 with [(4-BrC6H4)3N](SbCl6) led to isolation of 5 and [Ir(tpp)(PPh3)(H2O)]+, respectively. The crystal structures of complexes 3, 4, and 7-10 have been determined.

Heterobimetallic rhenium nitrido complexes containing the Kläui tripodal ligand [Co(η(5)-C5H5){P(O)(OEt)2}3](-).

Rhenium nitrido complexes containing the Kläui tripodal ligand [Co(η(5)-C5H5){P(O)(OEt)2}3](-) (LOEt(-)) have been synthesised and their reactions with [Ir(I)(cod)Cl]2 (cod = 1,5-cyclooctadiene) and [Rh(II)2(OAc)4] (OAc(-) = acetate) have been studied. The treatment of [Bu(n)4N][Re(VI)(N)Cl4] with NaLOEt in methanol afforded the Re(VI) nitride [Re(VI)(LOEt)(N)Cl(OMe)] (1). Reactions of 1 with [Ir(I)(cod)Cl]2 and [Rh(II)2(OAc)4] gave the µ-nitrido complexes [(LOEt)(OMe)ClRe(VI)(µ-N)Ir(I)(cod)Cl] (2) and [Rh(II)2(OAc)4{(µ-N)Re(VI)(LOEt)(OMe)Cl}2] (4), respectively. [(LOEt)Cl(PPh3)Re(V)(µ-N)Ir(I)(cod)Cl] (3) and [(LOEt)Cl(PPh3)Re(VI)(µ-N)Ir(I)(cod)Cl][PF6] (3·PF6) have been synthesised from the reactions of [Ir(I)(cod)Cl]2 with [Re(V)LOEt(N)Cl(PPh3)] and [Re(VI)LOEt(N)Cl(PPh3)](PF6), respectively. Similarly, the redox pair [Rh(II)2(OAc)4{(µ-N)Re(V)(LOEt)(PPh3)Cl}2] (5) and [Rh(II)2(OAc)4{(µ-N)Re(VI)(LOEt)(PPh3)Cl}2](PF6)2 (·(PF6)2) have been synthesised from the reactions of [Rh2(OAc)4] with [Re(V)LOEt(N)Cl(PPh3)] and [Re(VI)LOEt(N)Cl(PPh3)](PF6), respectively. While [(LOEt)Cl2Ru(VI)(µ-N)Ir(I)(cod)] (6) was obtained from [Ru(VI)(LOEt)(N)Cl2] and [Ir(I)(cod)Cl]2, the interaction between [Ru(VI)(LOEt)(N)Cl2] and [Rh(II)2(OAc)4] in CH2Cl2 is reversible. The crystal structures of complexes 2, 3, 3·PF6, 5, 5·(PF6)2 and 6 have been determined. X-ray crystallography indicates that the nitrido bridges in 2, 3, 3·PF6 and 6 can be described as MN-Ir (M = Re, Ru) showing Ir-N multiple bond character, whereas the interaction between Re≡N and Rh in 5 and 5·(PF6)2 is mostly of the donor-acceptor type. The electrochemistry of the Re nitrido complexes has been investigated by cyclic voltammetry.