ETH Zurich. personal coinmunication [7] A. Pape. Diplomarbeit. Universitit Konstanr. 1992, and unpublished uork. [XI Crystal structure data of 2: Enraf-Nonius CAD4 diffractometer. Mo,, radia-Lion. ;. = 0.71069 A. graphitc monochromator. T = 183(2) K. C,,H,,Li,P,..If, = 464.344. triclinic. space group PT (No. 2). it = 9.648(2), h =I5 316(4). c = 20 OXl (6) A. x = 103.22(2). = 99.19(2). 7 = 91.04(2)-, I; = 2847(1) A3. Z = 4 dimers. pLrlid = 1.083 g c r C 3 , p(MoKJ = 2.7 cm-', F(000) = 992. The integrated intensities of a total of 13677 reflections were measured, 1290X of which were unique (R,,,, = 0 023, ((sin 8):j.)mdx = 0.647 k'. hki i-ange + 12. f 19, k25. 3 2 3 scans. Aw = 0.9 + 0.35 tan 3). Lorentr-polarization correctionc were applied, those for intensity decay ( -1.6 %) and absorption were not considered necessary The structure was d v e d by automated Patterson methods (SHELXS-86). All 75 H atoms except one were located in difference syn-
Ligands containing multiple binding sites are of interest for the construction of structural and reactivity models of certain metallobiomolecules as well as polyelectronic systems."' The ligand 3,6-bis(T-pyridyI)pyridazine (dppn)Iz1 complexes a variety of metal ions, [3] and given our interest in dicopper-containing proteins, the binuclear copper(I1) complexes of dppn attracted our attention.I4I Therefore, we studied the interaction of copper(1) ions with this ligand and report here the structure and some properties of the resultant complexes. Scheme 1 Structure of the dppn hgand. The numbering is based on the interpretation of its NMR spectra.When 2 equivalents of dppn were added to 1 equivalent of [Cu(CF,SO,)], . C6H6['] in benzene, a brown precipitate was isolated (85 % yield) and recrystallized as brown crystals from acetone and ether. Microanalytical results combined with the FAB+ mass spectrum (FAB = Fast Atom Bombardment) indicate that the isolated product is the tetrameric complex 1.The 'H and I3C NMR spectra of 1 reveal the molecule to be highly symmetric, with a pattern of resonances similar to that of the free ligand. Additionally, the IR spectrum of 1 indicates that dppn binds in a tetradentate fashion.[4a1 X-ray quality crystals of 1 . 2CH,OH were obtained from a 1 : 1 : 1 mixture of methanol/acetone/ethanol.shows that the complex consists of discrete [ C~, ( d p p n )~]~+ ions and uncoordinated triflate ions with two methanol molecules of crystallization. The structure of the complex cation (Fig. I), which has crystallographically imposed C, symmetry about the Cul -Cu2 diagonal, is best described as a planar arrangement of four copper atoms lying at the vertices of a slightly distorted rhombus, with sides of length 3.566 (1) 131.8(3), N9-Cu3-N27 132.5(2), N9-Cu3-N32 117.5(2), N14-Cu3-N27 119.3(2), 107.2(3). N19-Cul-N26 and N19-Cul-N26 80.212). N19-Cul-N26' and N19-and Nl'-Cu2-N8' 79.9(2), NI-Cu2-N8' and Nl'-Cu2-N8 132.0(2), NS-Cu2-N8' N14-Cu3-N32 131.1(2), N9-Cu3-NI4 El.8(2), N27-Cu3-N32 81.7(2). Bottom: Representation of 1 .2CH,OH using the Chem-Ray program. atoms are spanned by four dppn ligands, two lying above the Cu, mean plane and two below. The distorted tetrahedral environment about each copper(1) ion is provided by two different dppn ligands, each of which supply a pyridine and a pyridazine nitrogen donor atom. Each of the individual
A large series of alkyne-substituted oligopyridines based on 2,2'-bipyridine, 1,10-phenanthroline, 2,2':6',2"-terpyridine, or 1,8-naphthyridine substrates has been synthesized and fully characterized. The palladium(0)-catalyzed coupling of bromo- or chloro-substituted derivatives with (trimethylsilyl)acetylene proceeds readily in diisopropylamine under ambient conditions giving good yields of the corresponding alkyne-substituted substrates oligoPy(C&tbd1;C)SiMe(3). The terminal monoynes oligoPyC&tbd1;CH become available upon treatment with K(2)CO(3) in methanol. Stepwise homologation of the acetylene function by Cadiot-Chodkiewicz coupling of oligoPyC&tbd1;CH with (bromoethynyl)triethylsilane (BrC&tbd1;CSiEt(3)) affords, in good yield, the silylated diynes oligoPy(C&tbd1;C)(2)SiEt(3), from which the terminal diynes oligoPy(C&tbd1;C)(2)H are formed by treatment with aqueous methanolic alkali. Reaction of oligoPy(C&tbd1;C)(2)H with BrC&tbd1;CSiEt(3) yields the silylated triynes oligoPy(C&tbd1;C)(3)SiEt(3) in modest yield. Further homologation is limited by nucleophilic attack of n-propylamine at the C-2 carbon of the alkyne chain, giving rise to a mixture of cis/cis (48%), cis/trans (33%), and trans/trans (19%) enaminediyne compounds 21a-c. Glaser oxidative self-coupling of the terminal diynes provides access to ditopic bipyridine or terpyridine ligands oligoPy(C&tbd1;C)(4)oligoPy comprising a tetrayne spacer. Quantitative formation of air-stable copper(I) complexes is described for the 6,6'-substituted ligands. A single crystal X-ray structure of complex 22a shows that the two ligands are interlocked around the copper(I) center in a pseudotetrahedral arrangement, similar to the structure deduced from NMR and FAB(+) data. The synthetic methods reported herein represent a valuable approach to the large-scale preparation of alkyne-functionalized oligopyridines.
Catalytic reactions of the type dichloromethane → ketene and chlorobenzene → benzoic acid esters (or benzaldehyde) are possible with Pd complexes, although the turnover numbers are still small. The CCl bond in CH2C12 is even activated by [Pd(PCy3)2(dba)]/PCy3 and the CCl bond in PhCI by Pd(CH3COO)2/PCy3 (Cy = cyclohexyl). The nature of the phosphane is decisive in these reactions : their basicity and cone angle must lie within a certain range. Initial products in the carbonylation are complexes 1 and 2.
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