π-Rich σ²P-Heterocycles: Bent η¹-P- and μ²-P-Coordinated 1,3-Benzazaphosphole Copper(I) Halide Complexes

Abstract

The reaction of 1-neopentyl-1,3-benzazaphosphole 1 with CuCl, CuBr, or Cu(SMe2)Br in THF at room temperature provides sparingly soluble [Cu7(μ(2)-L6)(μ(2)-X7)](+)[CuX2](-) cluster complexes 2a,b (L indicates coordinated 1, a X = Cl, b X = Br), with loosely bound THF, in high yields. The conversions proceed via transient THF-soluble labile [(L2CuX)2] complexes. Separation before complete conversion, combined with suitable conditions for crystallization, allowed these intermediates to be trapped. Depending on the reactant ratios, crystals of the clusters or of dimeric L2CuX complexes were formed. The crystal structure analyses of 2a·4THF and the dimers 3b [{Cu(η(1)-L)2(μ(2)-Br)}2], 4b [{Cu(μ(2)-L)(η(1)-L)(κBr)}2], 5a·2MeOH, and 5b·2MeOH [{Cu(μ(2)-L)(η(1)-L)(κX···HOMe)}2] generally display μ(2)-P- and/or tilted η(1)-P-coordination, contrasting with the preference for the η(1)-P in-plane coordination mode of phosphinine ligands in their copper(I) halide complexes. DFT studies of geometry-optimized monomers LCuBr, L(CuBr)2, L2CuBr, and the dimers 3b and 4b, calculated at the ωB97xD/cc-PVDZ level, suggest that weak competing interactions with the solvent THF and the entropy factor of the dimerization result in lability and a subtle balance between the different complexes in solution, whereas the particular coordination observed in the crystals is attributable to conservation of the delocalized π-system in the ligand. The HOMO of 4b is composed of Cu d orbitals and the π-type HOMO of the bridging ligand. Interestingly, despite the rather short Cu···Cu interatomic separation (2.726 Ǻ), no bond critical point could be located in 4b, indicating the absence of weak cuprophilic interactions in this compound.

One‐Pot Synthesis of Phosphanylbis(N‐arylglycines) and Spontaneous Diastereoselective Lactamization of P‐Alkyl Derivatives To Form Five‐Membered P,N‐Heterocyclic Amino Acids

“…Although the latter form reasonably active ethylene oligomerization catalysts with Ni(COD) 2 displaying the same selectivity as nickel phosphanylacetate catalysts, well‐defined phosphanylglycinate Ni complexes have not yet been isolated. Thus far, the only complex of an α‐phosphanylamino acid except (OC) 5 M–PPh 2 CH(COOH)NH– p Tol (M = Cr, Mo, W) is a crystallographically characterized lithium 1,3‐benzazaphospholine‐2‐carboxylate Rh(COD)Cl complex . Facile access to compounds such as 2 , reported herein, paves the way to transition metal complex chemical and catalytic studies of such α‐phosphanyl amino acid derivatives.…”

Chemistry of α‐Phosphanyl α‐Amino Acids

“…The latter were investigated also by us and found to be tolerant to some Lewis base additives including amines . Defined nickel complexes with phosphanylglycinate or 3‐phosphaprolinate ligands have not yet been isolated, but a first [RhCl(COD)(benzazaphospholin‐2‐lithium carboxylate)] 4 complex 22 was found to be stable and was structurally characterized by single‐crystal XRD analysis as a tetramer with Li ··· O coordination to each two neighbor molecules (Figure ) . This and the somewhat lower sensitivity of PG s to deuterolysis in alkaline NaOD/D 2 O compared to neutral solutions suggest improved stability of phosphanylglycinate or 3‐phosphaprolinate anions and prompted us to screen a number of the α‐phosphanyl amino acids for in‐situ formation of nickel catalysts, active in ethylene oligomerization.…”

Organophosphorus Compounds in Organic Electronics

“…To date, the class of 1,3‐benzazaphospholes is underexplored as opto‐electronic materials. Recently, some interesting studies appeared exemplifying their rich coordination chemistry towards Cu I halides, yielding potentially also optically interesting coordination compounds …”