2,4-Dichloronorlichexanthone

The zwitterionic complex formed by NiII and 2,2':6',2″-terpyridine-4'-carboxylate, Ni(tpyc)2, has been used as a coligand with a diverse group of polycarboxylates in uranyl ion complexes synthesized under solvo-hydrothermal conditions, thus giving a series of 14 mixed ligand, heterometallic compounds. Both [(UO2)2(c-1,2-chdc)Ni(tpyc)2(NO3)2]2·4CH3CN (1) and [(UO2)2(tdc)Ni(tpyc)2(NO3)2]2 (2), where c-1,2-chdc2- is cis-1,2-cyclohexanedicarboxylate and tdc2- is 2,5-thiophenedicarboxylate, display discrete U4Ni2 dinickelatetrauranacycles, a motif which is also found as part of a daisychain coordination polymer in [(UO2)4(bdc)3Ni2(tpyc)4(NO3)2]·2CH3CN·2H2O (3), where bdc2- is 1,4-benzenedicarboxylate. Similar U4Ni2 rings associate to form a nanotubular polymer in [(UO2)2(tca)Ni(tpyc)2(NO3)]·2CH3CN·2H2O (4), where tca3- is tricarballylate. [(UO2)2(1,2-pda) (1,2-pdaH)Ni(tpyc)2(NO3)]·CH3CN (5), where 1,2-pda2- is 1,2-phenylenediacetate, crystallizes as a meander-like chain in which each bent section can be seen as an open, semi-U4Ni2 ring. Oxalate (ox2-) gives [(UO2)2(ox)2Ni(tpyc)2] (6), a monoperiodic polymer containing smaller U4Ni rings, while 1,2,3-benzenetricarboxylate (1,2,3-btc3-) and citrate (citH3-) give [Ni(tpycH)(H2O)3][UO2(1,2,3-btc)]2·2H2O (7) and [UO2Ni2(tpyc)4][UO2(citH)]2 (8), two complexes with charge separation, the latter displaying one-periodic + two-periodic semi-interpenetration. [(UO2)2(btcH)Ni(tpyc)2(NO3)] (9) and [(UO2)2(cbtcH)Ni(tpyc)2(NO3)] (10), where btc4- and cbtc4- are 1,2,3,4-butanetetracarboxylate and cis,trans,cis-1,2,3,4-cyclobutanetetracarboxylate, respectively, are diperiodic networks with hcb topology, and [(UO2)2(ndc)Ni(tpyc)2(OH)(NO3)] (11), where ndc2- is 2,6-naphthalenedicarboxylate, is a sql network containing dinuclear nodes and involving 100-membered U10Ni4 metallacyclic units. U4Ni2 rings are found in the diperiodic polymer formed in [(UO2)4(t-R-1,2-chdc)4Ni2(tpyc)4] (12), where t-R-1,2-chdc2- is trans-R,R-1,2-cyclohexanedicarboxylate, the heavily puckered sheets being interlocked. 1,3-Phenylenediacetate (1,3-pda2-) gives a very thick diperiodic polymer with KIa topology, [(UO2)4(1,3-pda)4Ni2(tpyc)4]·CH3CN·2H2O (13). A triperiodic framework is formed with nitrilotriacetate (nta3-) in [(UO2)2(nta)2Ni2(tpyc)2] (14), where NiII is found in Ni(tpyc)2 units as well as in Ni(nta)24- moieties which both act as 4-coordinated nodes.

A polymer [Pd(CH2SO2C6H4Me)2]n is obtained by thermolysis of cis-[Pd(CH2SO2C6H4Me)2(NCMe)2] to release the MeCN ligands. The corresponding coordination sites are then occupied by weak Pd-O bonds, easier to break than the previous Pd-N bonds. This allows us to produce from the polymer cis complexes containing ligands weaker than NCMe, such as acetone or water. The complexes cis-[Pd(CH2SO2C6H4Me)2{OC(CD3)2}2], cis-[Pd(CH2SO2C6H4Me)2(OH2)2], and cis-[Pd(CH2SO2C6H4Me)2(OH2){OC(CD3)2}], and cyclic dimers [Pd(CH2SO2C6H4Me)2(OH2)]2 with bridging methylsulphone groups are formed. The Pd : PPh3 : OH2 1 : 1 : 1 reaction of the polymer produces cis-[Pd(CH2SO2C6H4Me)2(OH2)(PPh3)], which isomerizes to trans-[Pd(CH2SO2C6H4Me)2(OH2)(PPh3)], with water O-coordinated to Pd and making hydrogen bonds to the two SO2 groups as seen in its X-ray structure. A similar role is played by RNH2 groups in the structures of trans-[Pd(CH2SO2C6H4Me)2(NH3)(PPh3)] and the dimer μ-(N2H4)(trans-[Pd(CH2SO2C6H4Me)2(PPh3)])2. In addition to these interesting intramolecular hydrogen bonding properties provided by the SO2 groups, the structural and 1H NMR data available suggest that the CH2SO2C6H4Me group is an interesting kind of strong alkyl σ donor, with high trans influence, and forms very stable Pd complexes extraordinarily resistant to reductive elimination and to hydrolysis by water at room temperature.

The chemistry of Fe2(μ-SH)2(CO)4(PPh3)2 (2HH) is described with attention to S-S coupling reactions. Produced by the reduction of Fe2(μ-S2)(CO)4(PPh3)2 (2), 2HH is an analogue of Fe2(μ-SH)2(CO)6 (1HH), which exhibits well-behaved S-centered redox. Both 2HH and the related 2MeH exist as isomers that differ with respect to the stereochemistry of the μ-SR ligands (R = H, Me). Compounds 2HH, 2MeH, and 2 protonate to give rare examples of Fe-SH and Fe-S2 hydrides. Salts of [H2]+, [H2HH]+, and [H2MeH]+ were characterized crystallographically. Complex 2HH reduces O2, H2O2, (PhCO2)2, and Ph2N2, giving 2. Related reactions involving 1HH gave uncharacterizable polymers. The differing behaviors of 2HH and 1HH reflect stabilization of the ferrous intermediates by the PPh3 ligands. When independently generated by the reaction of 2HH with 2,2,6,6-tetramethyl-1-piperidinyloxy, 2* quantitatively converts to 2 or, in the presence of C2H4, is trapped as the ethanedithiolate Fe2(μ-S2C2H4)(CO)4(PPh3)2. Evidence is presented that the Hieber-Gruber synthesis of 1 involves polysulfido intermediates [Fe2(μ-S n)2(CO)6]2- ( n > 1). Two relevant experiments are as follows: (i) protonation of [Fe4(μ-S)2(μ-S2)CO)12]2- gives 1 and 1HH, and (ii) oxidation of 1HH by sulfur gives 1.