Turning a "useless" ligand into a "useful" ligand:a magneto-structural study of an unusual family of Cu(II) wheels derived from functionalised phenolic oximes

While the phenolic oximes (R-saoH(2)) are well known for producing monometallic complexes of the type [MII(R-saoH)(2)] with Cu-II ions in near quantitative yield, their derivatisation opens the door to much more varied and interesting coordination chemistry. Here we show that combining the complimentary diethanolamine and phenolic oxime moieties into one organic framework (H4L1 and H4L2) allows for the preparation and isolation of an unusual family of [Cu-II](n) wheels, including saddle-shaped, single-stranded [Cu-8(II)] wheels of general formula [Cu-8(HL1)(4)(X)(4)] n[Y] (when n = 0, X = Cl-, NO3-, AcO-, N-3(-); when n = 2+X = (OAc)(2)/(2,2'-bpy)(2) and Y = [BF4](2)) and [Cu-8(HL2)(4)(X)(4)](X = Cl-, Br-), a rectangular [Cu-6(HL1)(4)] wheel, and a heterometallic [Cu4Na2(HL1)2(H2L1)(2)] hexagon. Magnetic studies show very strong antiferromagnetic exchange between neighbouring metal ions, leading to diamagnetic ground states in all cases. DFT studies reveal that the magnitude of the exchange constants are correlated to the Cu-N-O-Cu dihedral angles, which in turn are correlated to the planarity/puckering of the [Cu-II](n) rings

Metal[BOND]metal bond formation between [n]metallocenophanes: Synthesis and characterisation of a dicarba[2]ruthenocenophanium dimer

Feeling the strain: The first example of metal-metal bonding between strained nmetallocenophanes is reported. A dicarba2ruthenocenophanium dimer has been synthesised through the oxidation of a dicarba2ruthenocenophane (see figure). The structural and electrochemical characterisation of the dimer is also discussed

Influence of cyclopentadienyl ring-tilt on electron-transfer reactions: Redox-induced reactivity of strained 2 and 3 Ruthenocenophanes

In contrast to ruthenocene Ru((5)-C5H5)(2) and dimethylruthenocene Ru((5)-C5H4Me)(2) (7), chemical oxidation of highly strained, ring-tilted 2ruthenocenophane Ru((5)-C5H4)(2)(CH2)(2) (5) and slightly strained 3ruthenocenophane Ru((5)-C5H4)(2)(CH2)(3) (6) with cationic oxidants containing the non-coordinating B(C6F5)(4)(-) anion was found to afford stable and isolable metalmetal bonded dicationic dimer salts Ru((5)-C5H4)(2)(CH2)(2)(2)B(C6F5)(4)(2) (8) and Ru((5)-C5H4)(2)(CH2)(3)(2)B(C6F5)(4)(2) (17), respectively. Cyclic voltammetry and DFT studies indicated that the oxidation potential, propensity for dimerization, and strength of the resulting RuRu bond is strongly dependent on the degree of tilt present in 5 and 6 and thereby degree of exposure of the Ru center. Cleavage of the RuRu bond in 8 was achieved through reaction with the radical source (CH3)(2)NC(S)SSC(S)N(CH3)(2) (thiram), affording unusual dimer (CH3)(2)NCS2Ru((5)-C5H4)((3)-C5H4)C2H4(2)B(C6F5)(4)(2) (9) through a haptotropic (5)-(3) ring-slippage followed by an apparent 2+2 cyclodimerization of the cyclopentadienyl ligand. Analogs of possible intermediates in the reaction pathway C6H5ERu((5)-C5H4)(2)C2H4B(C6F5)(4) E=S (15) or Se (16) were synthesized through reaction of 8 with C6H5EEC6H5 (E=S or Se)