Bridging Azines in the Coordination Sphere of Low-Valent Vanadocene Derivatives

Structural and electronic elucidation of a N-heterocyclic silylene vanadocene adduct

The formation mechanism and bonding in a rare vanadocene complex with N-heterocyclic silylene (1,3-bis(2,6-diisopropylphenyl)-1,3-diaza-2-silacyclopent-4-en-2-ylidene) is elucidated using a combination of experimental and theoretical techniques.

Influence of the 5f Orbitals on the Bonding and Reactivity in Organoactinides: Experimental and Computational Studies on a Uranium Metallacyclopropene

The synthesis, structure, and reactivity of a uranium metallacyclopropene were comprehensively studied. Reduction of (η(5)-C5Me5)2UCl2 (1) with potassium graphite (KC8) in the presence of bis(trimethylsilyl)acetylene (Me3SiC≡CSiMe3) allows the first stable uranium metallacyclopropene (η(5)-C5Me5)2U[η(2)-C2(SiMe3)2] (2) to be isolated. Magnetic susceptibility data confirm that 2 is a U(IV) complex, and density functional theory (DFT) studies indicate substantial 5f orbital contributions to the bonding of the metallacyclopropene U-(η(2)-C═C) moiety, leading to more covalent bonds between the (η(5)-C5Me5)2U(2+) and [η(2)-C2(SiMe3)2](2-) fragments than those in the related Th(IV) compound. Consequently, very different reactivity patterns emerge, e.g., 2 can act as a source for the (η(5)-C5Me5)2U(II) fragment when reacted with alkynes and a variety of heterounsaturated molecules such as imines, bipy, carbodiimide, organic azides, hydrazine, and azo derivatives.

Novel trisphosphine ligand containing 1,3,5-triazine core, [2,4,6-C3N3{C6H4PPh2-p}3]: synthesis and transition metal chemistry

The trisphosphine ligand with triazine core, 2,4,6-tris{4-(diphenylphosphino)phenyl}-1,3,5-triazine (2), was synthesized in moderate yield by reacting 2,4,6-tris(4-bromophenyl)-1,3,5-triazine with 3 equiv of KPPh2. The tris(phosphine) 2 undergoes facile oxidation to give trischalcogenides 2,4,6-C3N3{C6H4P(E)Ph2-p}3 (E = O, 3; S, 4; Se, 5) on treatment with aqueous H2O2, elemental sulfur, or selenium. The reaction between 2 and [AuCl(SMe2)] yielded a trinuclear complex, [(AuCl)3{2,4,6-C3N3(C6H4PPh2-p)3}] (6), which on further treatment with pyridyl ligands such as 2,2'-bipyridine (2,2'-bpy) and 1,10-phenanthroline (1,10-phen) produced the mixed-ligand complexes [{Au(2,2'-bpy)}3{2,4,6-C3N3(C6H4PPh2-p)3}](OTf)3 (7) and [{Au(1,10-phen)}3{2,4,6-C3N3(C6H4PPh2-p)3}](OTf)3 (8), where OTf indicates trifluoromethansulfonate. Several trimetallic complexes such as [{Ru(η(6)-cymene)Cl2}3{2,4,6-C3N3(C6H4PPh2-p)3}] (9), [{Pd(η(3)-C3H5)Cl}3{2,4,6-C3N3(C6H4PPh2-p)3}] (10), [{Rh(COD)Cl}3{2,4,6-C3N3(C6H4PPh2-p)3}] (11) and [{Ir(COD)Cl}3{2,4,6-C3N3(C6H4PPh2-p)3}] (12) have also been synthesized and characterized. The reactions of 2 with [M(COD)Cl2] and CuI afforded metallo-cyclophane type complexes, [(MCl2)3L2] (M = Pd; 13, Pt; 14) (L = 2,4,6-tris{4-(diphenylphosphino)phenyl}-1,3,5-triazine) and [(CuI)3L2] (15), in good yield.