Coordination chemistry of a new rigid, hexadentate bispidine-based bis(amine)tetrakis(pyridine) ligand.

The hexadentate bispidine-based ligand 2,4-bis(2-pyridyl)-3,7-bis(2-methylenepyridine)-3,7-diazabicyclo[3.3.1]nonane-9-on-1,5-bis(carbonic acid methyl ester), L(6m), with four pyridine and two tertiary amine donors, based on a very rigid diazaadamantane-derived backbone, is coordinated to a range of metal ions.

Synthesis, photochemistry and photophysics of stilbene-derivatized fullerenes.

The photochemistry and photophysics of two sets of stilbene-derivatized fullerene isomers, in which stilbene is covalently linked to C60, are described. Synthesis and characterization of cis- and trans-stilbene substituted methanofullerenes 1 and 2, and cis- and trans-stilbene substituted fulleropyrrolidines 7 and 8 are described. While UV irradiation of the stilbene-substituted ketal precursors to 1 and 2 lacking the fullerene moiety afforded a photostationary state with 90:10 cis:trans ratio, similar to that of other model stilbene systems, direct and fluorenone-sensitized irradiation of 1 and 2 led to complete conversion to the trans isomer 2, as determined by HPLC analysis.

Novel Ring Contraction Reaction for the Synthesis of Functionalized Tetrathiamacrocyclic Ligand Molecules.

Chlorination of [14]aneS(4)-ol (1,4,8,11-tetrathiatetradecan-6-ol) and cis/trans-[14]aneS(4)-diol (cis/trans-1,4,8,11-tetrathiatetradecane-6,13-diol) yields the corresponding dichloro-substituted macrocycles [14]aneS(4)-Cl (1,4,8,11-tetrathiatetradecane 6-chloride) and cis/trans-[14]aneS(4)-Cl(2) (cis/trans-1,4,8,11-tetrathiatetradecane 6,13-dichloride) in good yield. Thiomethylation of the chlorides produces the ring-contracted pendent thioether macrocycles [13]aneS(4)-CH(2)SCH(3) (1,4,7,10-tetrathiatridecane-5-(methylthio)methane) and cis/trans-anti-[12]aneS(4)-(CH(2)SCH(3))(2) (1,4,7,10-tetrathiadodecane-5,11-bis((methylthio)methane)). The mechanism of the ring contraction reaction is discussed in terms of the reactivity of the monochlorinated macrocycle toward ring contraction and the stereochemistry of the chlorinated intermediates and the thiomethylated products, which are based on the X-ray crystal structure analyses of trans-[14]aneS(4)-Cl(2) and trans-anti-[12]aneS(4)-(CH(2)SCH(3))(2).

A Dinuclear Nickel(II) Complex with Readily Accessible Coordination Sites and Additional N-Functional Groups in Proximity to the Bimetallic Core.

A series of pyrazolate-based dinuclear Ni(II) complexes relevant to the active site of urease are reported. Deprotonation of HL(1) [HL(1) = 3,5-bis(R(2)NCH(2))-pyzH; R(2)N = Me(2)N(CH(2))(3)NMe] by means of 1 equiv of BuLi and subsequent reaction with 2 equiv of [Ni(H(2)O)(6)](ClO(4))(2) in the presence of NEt(i)Pr(2) affords the dinuclear complex [L(1)Ni(2)(OH)(MeCN)(2)](ClO(4))(2) (1). This is shown crystallographically to contain two five-coordinate nickel ions bridged by both the pyrazolate and a hydroxide, with an acetonitrile solvent molecule bound to each metal center.

Ruthenium Complexes Containing "Noninnocent" o-Benzoquinone Diimine/o-Phenylenediamide(2-) Ligands. Synthesis and Crystal Structure of the Nitrido-Bridged Complex [{LRu(o-C(6)H(4)(NH)(2))}(2)(&mgr;-N)](PF(6))(2).3CH(3)CN.C(6)H(5)CH(3).

Reaction of LRu(III)Cl(3) (L = 1,4,7-trimethyl-1,4,7-triazacyclononane) with 1,2-phenylenediamine (opdaH(2)) in H(2)O in the presence of air affords [LRu(II)(bqdi)(OH(2))](PF(6)) (1), where (bqdi) represents the neutral ligand o-benzoquinone diimine. From an alkaline methanol/water mixture of 1 was obtained the dinuclear species [{LRu(II)(bqdi)}(2)(&mgr;-H(3)O(2))](PF(6))(3) (1a). The coordinated water molecule in 1 is labile and can be readily substituted under appropriate reaction conditions by acetonitrile, yielding [LRu(II)(bqdi)(CH(3)CN)](PF(6))(2) (2), and by iodide and azide anions, affording [LRu(II)(bqdi)I](PF(6)).