Synthesis and Structures of Rh^I and Ir^I Complexes Supported by N‐Heterocyclic Carbene‐Phosphinidene Adducts

Abstract

N-Heterocyclic carbene-phosphinidene adducts of the type (IDipp)PR [R = Ph (5), SiMe 3 (6); IDipp = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene] were used as ligands for the preparation of rhodium(I) and iridium(I) complexes. Treatment of (IDipp)PPh (5) with the dimeric complexes [M(μ-Cl)(COD)] 2 (M = Rh, Ir; COD = 1,5-cyclcooctadiene) afforded the corresponding metal(I) complexes [M(COD)Cl{(IDipp)PPh}] [M = Rh (7) or Ir (8)] in moderate to good yields. The reaction of (IDipp)PSiMe 3 (6) with [Ir(μ-Cl)(COD)] 2 did 44 not yield trimethylsilyl chloride elimination product, but furnished the 1:1 complex, [Ir(COD)Cl{(IDipp)PSiMe 3 }] (9). Additionally, the rhodium-COD complex 7 was converted into the corresponding rhodiumcarbonyl complex [Rh(CO) 2 Cl{(IDipp)PPh}] (10) by reaction with an excess of carbon monoxide gas. All complexes were fully characterized by NMR spectroscopy, microanalyses, and single-crystal X-ray diffraction studies.

Cationic Iridium(I) NHC‐Phosphinidene Complexes and Their Application in Hydrogen Isotope Exchange Reactions

“…All four complexes display the expected square‐planar coordination spheres around the iridium atoms. The iridium‐phosphorus bonds of 2.3371(6)/2.3414(6) Å and 2.3481(4) Å in complexes 2 and 3 are slightly shorter than in the related NHC‐phosphinidene complexes [{(IDipp)PPh}Ir(cod)Cl] (2.3544(6) Å) and [{(IDipp)PSiMe 3 }Ir(cod)Cl] (2.4018(7) Å), [46] but longer than in the neutral triphenylphosphine complex [Ir(cod)Cl(PPh 3 )] (2.3041(17) Å) [47] . Upon chloride abstraction, only a slight shortening in the Ir−P bond lengths (2.3058(7)/2.2989(7) Å) is observed in complex 4 , while the Ir−P1 bond length of 2.3393(5) Å in complex 5 is almost identical to that in 3 .…”

Rhodium and Iridium Complexes of Anionic Thione and Selone Ligands Derived from Anionic N‐Heterocyclic Carbenes

“… [6] In contrast, no elimination of Me 3 SiCl was observed with iridium, but instead the monometallic complex [{(IDipp)PSiMe 3 }Ir(COD)Cl] was isolated. [25] Therefore, the reactions of the silylated sulfur congener 3 with [M(COD)Cl] 2 were initially studied by NMR spectroscopy, which, depending on the stoichiometry, resulted in a clean formation of the corresponding mono‐ and bimetallic complexes 9 and 13 . However, since the preparation of the silylated educts 3 and 4 proceeded via the lithium species 1 and 2 with a significant loss of yield, they were also directly employed for the synthesis of the corresponding rhodium and iridium COD complexes 9 – 12 and 13 – 16 (Scheme 2 ).…”

Coordination and Reactivity Studies of Titanium Complexes of Monoanionic Inversely Polarized Phosphaalkene–Ethenolate Ligands

“…Other studies have subsequently been reported, primarily focusing on their use as monodentate ligands . Metal carbonyl complexes of related phosphaalkenes (such as G ) showed substantially lower CO stretching frequencies in comparison to the corresponding tertiary phosphine or NHC complexes, indicating strong electron donation of these IPPs. , This was further demonstrated by the isolation of bimetallic complexes (such as H ), which illustrates the ability of these phosphaalkenes to adopt mesomeric structure B (Figure ). − More recently, Tamm has reported ruthenium complexes of monoanionic phosphaalkenes, further expanding and demonstrating the scope and utility of these ligands ( I ) .…”

“…Metal carbonyl complexes of related phosphaalkenes (such as G ) showed substantially lower CO stretching frequencies in comparison to the corresponding tertiary phosphine or NHC complexes, indicating strong electron donation of these IPPs. , This was further demonstrated by the isolation of bimetallic complexes (such as H ), which illustrates the ability of these phosphaalkenes to adopt mesomeric structure B (Figure ). − More recently, Tamm has reported ruthenium complexes of monoanionic phosphaalkenes, further expanding and demonstrating the scope and utility of these ligands ( I ) . Despite their attractive features as spectator ligands, coordination complexes of these IPPs have not been studied for catalytic transformations outside of olefin metathesis and 1,6-enyne cyclization. , …”