A crown thioether molecule as bridging ligand and two types of cations in the molecule are the most striking features of the silver complex [Ag4L5](ClO4)4 (L = 1,4,7‐trithiacyclononane). In the cation [AgL2]⊕, Ag⊕ is surrounded by six S atoms, in the cation [Ag3L3]3⊕ by four. One S atom of each of the three ligands in [AgL,]3⊕ is bound to two Ag⊕. In contrast, the soft Lewis base I⊕ in [LCuI] competes with the S atoms for coordination positions. In the resulting monomeric units, Cu⊕ is coordinated in a distorted tetrahedral fashion by three S atoms and one I⊕.
Addition of base to the complexes [M ([9]aneS3)213+ ([9]aneS3 = 1,4,7-trithiacyclononane; M = Co, Rh, Ir) leads to deprotonation at a methylene carbon, and subsequent re-arrangement of the carbanion affords a vinyl thioether complex via C-S bond cleavage; for M = Co this process is reversed in acidic medium to regenerate [Co ( [9]aneS3)2]3+. The synthesis and structure of the complexes [M([9]aneS3)2I3+ (M = C O , ~ Rh,2 11-3) have been described. These octahedral complex cations show homoleptic hexathia co-ordination about the d6 metal ion. The redox interconversion of M1/VII1 species in which the trithia macrocycles can vary their co-ordination to accommodate these metal oxidation states has been achieved.1-3 We report herein a new type of reaction of [9]aneS3 with MI11 centres involving C-H activation at the co-ordinated thioether followed by ring-opening via C-S bond cleavage to afford vinyl thioether complexes. Addition of one molar equivalent of Et3N to solutions of the complexes [M([9]aneS3)2]3+ (M = Co, Rh, Ir) in MeCN or MeN02, or dissolution of [M([9]aneS3)#+ in water at pH > 4 leads to a rapid change in colour of the solutions: from orange to green (A, , , 685 nm) for Co, from colourless to red ( A , , , 474 nm) for Rh, and from colourless to yellow (Amax 379 nm) for Ir. A i,i [glane 5 3
Reaction of Ni(CH,C02),-4H,0 with N,N',N"-trimethyl-I ,4,7-triazacyclononane( L) in methanol and addition of solid NaCIO,.H,O yielded a blue-green binuclear nickel (11) complex containing a hydroxo and t w o acetate groups as bridging ligands. The crystal and molecular structure of the compound has been established by X-ray diffraction. It consists of binuclear cations [LNi(p-OH) (p-CH,CO,),NiL] +, unco-ordinated perchlorate anions, and water of crystallization. Variable temperature (4-300 K) magnetic susceptibility measurements show a weak antiferromagnetic exchange coupling (J = -4.5 cm-l, ( 9 ) = 2.1 7) between nickel centres with T , z 7.1 K. The
C-Functionalised derivatives of the macrocyclic thioether ligand 1,4,7-trithiacyclononane (9S3), synthesised from 3-thiapentane-I ,5-dithiol and a variety of substituted vicinal dibromides, retain the unusual coordination chemistry characteristic of the unsu bstituted 9S3 ligand.
The remarkable ring-current effect of the [26]porphyrin 7 is presumably due to the flattening effect of the four pyrrole rings; the two cationic centers support this effect somewhat but are not decisive."'] Thus, according to the 'H-NMR criterion, 7b contains a "superaromatic n-electron system." It demonstrates that the limits for aromatic behavior, so far expected to be reached with [26]annulenes, can be exceeded.Apart from the ring-current effect of the [26]porphyrin 7, its strong color intensity also deserves consideration. Thus, the molar extinction coefficient ( E ) of its most intense absorption band at 547nm (909600) is more than twice as large as that for the corresponding Soret band of porphyrins (maximally 400000). In the case of [26]porphyrin 7, the visual effect of the color is increased still further by the fact that its most intense band lies in the middle of the visible range. In contrast, the Soret band of the porphyrins at 400 nm, compared with the longer-wavelength satellite maxima that are smaller by an order of magnitude, contributes little to the depth of color.
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