Revealing the Role of the Cyaphide Ion as a Bridging Ligand in Heterometallic Complexes

Abstract

The synthesis of heterometallic transition metal complexes featuring bridging cyaphide ions (C≡P−) is reported. These are synthesized from reactions of Au(IDipp)(CP) (IDipp=1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene) with electron‐rich, nucleophilic transition metal reagents, affording Au(IDipp)(μ2−C≡P)Ni(MeIiPr)2 (MeIiPr=1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene) and Au(IDipp)(μ2−C≡P)Rh(Cp*)(PMe3). These studies reveal that, in contrast to the cyanide ion, bimetallic cyaphido complexes strongly favor a η1 : η2 coordination mode that maximizes the interaction of the second metal (Ni, Rh) with the π‐manifold of the ion (and not the phosphorus atom lone pair). End‐on bridging can be effectively unlocked by blocking the π‐manifold, as demonstrated by reaction of Au(IDipp)(μ2−C≡P)Rh(Cp*)(PMe3) with an electrophilic transition metal reagent, W(CO)5(THF), which affords the heterotrimetallic compound Au(IDipp)(μ3−C≡P)[Rh(Cp*)(PMe3)][W(CO)5].

Synthesis, Structure and Reactivity of a Cyapho(dicyano)methanide Salt

“…DFT calculations reveal that the lowest unoccupied molecular orbital (LUMO) of 2 has a significant contribution from an out‐of‐plane C−P π* interaction (Figure S30), which implies that reactions with the C≡P triple bond should be accessible. As phosphaalkynes are known to bind to transition metals complexes, [25] we reasoned that reaction of 2 with an electron‐rich transition metal fragment should allow access to the cyaphide moiety through LUMO‐driven reactivity [26] . Treatment of 2 with [Ni(COD)( Me IPr) 2 ] ( Me IPr=C[N i PrCMe] 2 ) in toluene afforded complex 4 , which features a singlet in its 31 P NMR spectrum at 45.4 ppm.…”

“…As phosphaalkynes are known to bind to transition metals complexes, [25] we reasoned that reaction of 2 with an electron‐rich transition metal fragment should allow access to the cyaphide moiety through LUMO‐driven reactivity. [26] Treatment of 2 with [Ni(COD)( Me IPr) 2 ] ( Me IPr=C[N i PrCMe] 2 ) in toluene afforded complex 4 , which features a singlet in its 31 P NMR spectrum at 45.4 ppm. The solid‐state molecular structure of [K(18‐crown‐6] 4 ⋅1.5 tol was determined by single crystal X‐ray diffraction (Figure 4 , top), which revealed a structure containing C−P−Ni three‐membered ring as expected.…”

Putting cyaphide in its place: determining the donor/acceptor properties of the κC-cyaphido ligand

“…19 A similar trend can be observed in the case of gold(I) Au(IDipp)X and [Au(Dipp)L] + complexes (Au X and Au L + ) which exhibit 13 C NHC chemical shis over a wide frequency range (∼50 ppm) depending on the nature of the ligand trans to the carbene (Table S9 †). 16,17,[20][21][22][23][24][25][26][27][28] Weak s donors (such as acetonitrile) give rise to low 13 C NHC chemical shis (e.g. Au NCMe + : 13 C NHC = 166.0 ppm), whereas strong donors (e.g.…”

“…1). 17 As traditional methods for probing ligand donor strength are currently inaccessible for the cyaphido liganddue to a lack of [M(CP) 6 ] x− or [M(CP) 4 ] x− type complexesin this study we focus on the use of both NMR spectroscopic and crystallographically determined bond metric data to do so. This allows us to deconvolute the donor/acceptor properties of the terminal kCcyaphido ligand through comparative studies of three cyaphido metal complexes, the gold(I) complex (IDipp)Au(CP) (Au CP ), the cobalt(I) complex Co( Dipp PDI)(CP) (Co CP ; Dipp It has been previously demonstrated that the N-heterocyclic carbene (NHC) carbenoid 13 C{ 1 H} NMR chemical shi ( 13 C NHC ) is sensitive to the s basicity of trans-coordinated co-ligands.…”

Synthesis, Structure and Reactivity of a Cyapho(dicyano)methanide Salt

“…As phosphaalkynes are known to bind to transition metals complexes, [25] we reasoned that reaction of 2 with an electron-rich transition metal fragment should allow access to the cyaphide moiety through LUMO-driven reactivity. [26] Treatment of 2 with [Ni(COD)( Me IPr) 2 ] ( Me IPr = C[N i PrCMe] 2 ) in toluene afforded complex 4, which features a singlet in its 31 P NMR spectrum at 45.4 ppm. The solid-state molecular structure of [K(18-crown-6]4•1.5 tol was determined by single crystal X-ray diffraction (Figure 4, top), which revealed a structure containing CÀ PÀ Ni three-membered ring as expected.…”