Frustrated and realized hydrogen bonding in 4-hydroxy-3,5- ditertbutylphenylphosphine derivatives

Accepted author manuscript. Embargo in effect until Feb. 28, 2023Synthesis and molecular and supramolecular structures of a series of triarylphosphines P(Ph)3–n{4-RO-3,5-(tBu)2-C6H2}n (n = 1, 3; R = SiMe3, H) are reported. Chemical oxidation products E=P(Ph)3–n{4-RO-3,5-(tBu)2-C6H2}n (E = O, S, and Se; n = 1, 3; R = SiMe3, H) are also reported. Crystal structures of the reported compounds were determined by single-crystal X-ray diffraction, using a Hirshfeld atom refinement with NoSpherA2 through OLEX2, which provides an average improvement in C–C bond distance precision of 35%. Phosphine basicity for the phosphines with n = 1, R = H and n = 3, R = SiMe3, H was determined using the 1JP,Se values of the respective selenides; 1JP,Se = 699 Hz for E = Se, n = 3, and X = H identifies the most basic triarylphosphine ever reported. Intermolecular interactions allow classification of the 17 structures into 4 categories: those with only dispersion-induced short contacts, those with frustration of H-bonding, those with only classic H-bonding, and those with combinations of classic and frustration of H-bonding. A “double phenol embrace” classified by an R22(4) graph set is a weak intermolecular synthon organizing lattices with 2,6-ditertbutylphenol functional groups. Classic H-bonding occurs only when E = O.Ye

Synthesis, characterization and anticancer activities of cationic η6-p-cymene ruthenium(II) complexes containing phosphine and nitrogenous ligands

Accepted author manuscript. Embargo in effect until June 23, 2024Ruthenium-based anticancer agents have created a center of attention in the field of inorganic medicinal chemistry. The first fully characterized cationic ruthenium(II)-arene complexes [Ru(η6-p-cymene) (PAr3)LNCl]+ with highly lipophilic PAr3 ligands where Ar = 3,5-((CH3)3C)2C6H3– (L1), 3,5-(CH3)2C6H3– (L2), 4-CH3O-3,5-(CH3)2C6H2– (L3) and 4-CH3O-C6H4– (L4) with N = 3-methylpyridine (1–4, respectively), or L4 and 4-methylpyridine (5), or L4 and CH3CN (6) were obtained (yields 67–91%) as solids stable to light and air. Electrical conductance indicates that all the complexes are 1:1 electrolytes in solution. Their composition and purity have been unambiguously established by single-crystal X-ray diffraction, NMR spectroscopy and elemental analysis. The coordination geometries are uniform for all six complexes and each structure consist of a unipositive complex cation bearing the phosphine ligands L1-L4 and LN = 3-methylpyridine, 4-methylpyridine or CH3CN attached to the organometallic fragment. The equivalent unit cell volumes per formula unit decrease with 1 > 3 > 2 > 4 > 5 > 6, accurately reflecting the decreasing sizes of the phosphines L1-L4, and a greater occupied volume for 3-methyl- vs. 4-methylpyridine, and the smallest volume contribution from CH3CN. Electrochemical studies showed mixed electrochemical mechanisms (EC/ECE) from partial substitution of p-cymene by CH3CN ligands from the solvent. A large electrochemical stability window (>2.2 V) for Ru(II) was observed extending beyond the physiological E° range. The complexes were cytotoxic against human cancer cell lines in vitro, and some complexes altered cell morphology