Low-valent homobimetallic Rh complexes: influence of ligands on the structure and the intramolecular reactivity of Rh–H intermediates

Supporting two metal binding sites by a tailored polydentate trop-based (trop - 5H-dibenzo[a,d] cyclohepten-5-yl) ligand yields highly unsymmetric homobimetallic rhodium(I) complexes. Their reaction with hydrogen rapidly forms Rh hydrides that undergo an intramolecular semihydrogenation of two C≡C bonds of the trop ligand. This reaction is chemoselective and converts C≡C bonds to a bridging carbene and an olefinic ligand in the first and the second semihydrogenation steps, respectively. Stabilization by a bridging diphosphine ligand allows characterization of a Rh hydride species by advanced NMR techniques and may provide insight into possible elementary steps of H₂ activation by interfacial sites of heterogeneous Rh/C catalysts

Salen supported Al-O-C≡P and Ga-P=C=O complexes

The first OCP adducts of aluminium and gallium are reported. The complexes are supported by sterically encumbered salen ligands and reveal a selective binding to O and P, respectively. Their reactivity with diazaphosphenium Lewis acids and N-heterocyclic carbene Lewis bases is described, in addition to cycloaddition reactions with s-tetrazines.ISSN:1477-9226ISSN:1477-923

Functionalization of P4 using a lewis acid stabilized bicyclo-[1.1.0]tetraphosphabutane anion

Reacting white phosphorus (P4) with sterically encumbered aryl lithium reagents (aryl=2,6-dimesitylphenyl or 2,4,6-tBu3C6H2) and B(C6F5)3 gives the unique, isolable Lewis acid stabilized bicyclo[1.1.0]tetraphosphabutane anion. Subsequent alkylation of the nucleophilic site of the RP4 anion gives access to non-symmetrical disubstituted bicyclic tetraphosphorus compounds. This novel method enables PC bond formation in a controlled fashion using white phosphorus as starting material

Functionalization of P4 using a lewis acid stabilized bicyclo-[1.1.0]tetraphosphabutane anion

Reacting white phosphorus (P4) with sterically encumbered aryl lithium reagents (aryl=2,6-dimesitylphenyl or 2,4,6-tBu3C6H2) and B(C6F5)3 gives the unique, isolable Lewis acid stabilized bicyclo[1.1.0]tetraphosphabutane anion. Subsequent alkylation of the nucleophilic site of the RP4 anion gives access to non-symmetrical disubstituted bicyclic tetraphosphorus compounds. This novel method enables PC bond formation in a controlled fashion using white phosphorus as starting material

Selective [3+1] Fragmentations of P4 by \01cP\01d Transfer from a Lewis Acid Stabilized [RP4]\212 Butterfly Anion

Two [3+1] fragmentations of the Lewis acid stabilized bicyclo[1.1.0]tetraphosphabutanide Li[Mes*P4⋅ BPh3] (Mes*=2,4,6-tBu3C6H2) are reported. The reactions proceed by extrusion of a P1 fragment, induced by either an imidazolium salt or phenylisocyanate, with release of the transient triphosphirene Mes*P3, which was isolated as a dimer and trapped by 1,3-cyclohexadiene as a Diels–Alder adduct. DFT quantum chemical computations were used to delineate the reaction mechanisms. These unprecedented pathways grant access to both P1- and P3-containing organophosphorus compounds in two simple steps from white phosphorus

Stabilization and Transfer of the Transient [Mes*P4 ](-) Butterfly Anion Using BPh3

The transient bicyclo[1.1.0]tetraphosphabutane anion, generated from white phosphorus (P4 ) and Mes*Li (Mes*=2,4,6-tBu3 C6 H2 ), can be trapped by BPh3 in THF. This Lewis acid stabilized anion can be used as an [RP4 ](-) transfer agent, reacting cleanly with neutral Lewis acids (B(C6 F5 )3 , BH3 , and W(CO)5 ) to afford unique singly and doubly coordinated butterfly anions, and with the trityl cation to form a neutral, nonsymmetrical, all-carbon-substituted P4 derivative. This reaction path enables a simple, stepwise functionalization of white phosphorus

Phosphanyl cyanophosphide salts: versatile PCN building blocks

The facile preparation of alkali salts of phosphanyl cyanophosphides [NHP-PCN]- (NHP=N-heterocyclic phosphenium) is reported. Their formation is achieved by isoelectronic replacement of O for [N]- in the phosphaketenes NHP-PCO using alkaline hexamethyldisilazide M[N(SiMe3)2] (M=Na, K) as reagent. The new anionic entities are versatile PCN building blocks which allow the formation of a diversity of new cyanophosphine derivates including the first example of a PCNB hetero-cumulene and a PCN-ligated transition metal complex

Functionalization of P4 in the coordination sphere of coinage metal cations

Selective functionalization of white phosphorus is achieved by addition of ArLi to unique cationic coinage metal η2–P4 complexes. This novel approach allows controlled P–C bond formation using the bulky DmpLi (Dmp = 2,6-Mes2C6H3) and the unencumbered MesLi, giving sterically diverse doubly complexed RP4 butterfly derivatives in a single step