Thienyl pyridines

Most of the substrates that give both types of cycloaurated complexes are limited to pyridine derivatives, although recently a few exceptions have been reported with thiazoles and imidazoles. The reaction of substituted pyridine ligands such as phpy,1 49,1924 2-benzoyl pyridine,1924 2-anili-nopyridine,1925,1926 l-(2-pyridylamino and 2-pyrimidinylamino)naphthalene, 7 2-phenoxypyri-dine,1811 2-(phenylsulfanyl)pyridine,1925 2-(2-thienyl)pyridine, 8 2-(3-thienyl)pyridine,1928 2-(alkylsulfanyl)pyridine,1929 or papavorine1930 at room temperature yields the nonmetallated compounds which, upon heating, are transformed into the metallated complexes [Au(N,C)Cl2], The process with phpy is illustrated in Scheme 21. 

The arylborane, or heteroarylborane (8 mmol), TBA-Br (1.28 g, 4 mmol), powdered KOH (11.8 g), the haloarene (12 mmol) and Pd(Ph3P)4 (0.46 g, 0.4 mmol) are refluxed in THF under N2 for 8 h. EtOAc (100 ml) is added to the cooled mixture and the organic mixture is washed with brine (40 ml) and dried (MgS04). Evaporation under reduced pressure and chromatography from silica gives the biaryl system [e.g. 3-(2-pyridyl)pyri-dine, 85% 3-(3-pyridyl)pyridine, 82% 3-(5-methoxycarbonyl-2-pyridyl)pyridine, 63% 3-(6-methoxy-2-pyridyl)pyridine, 77% 3-(2-thienyl)pyridine, 75%]. 

Marubayashi et al. <1997J(P2)1309> have also shown that solid-state dimerization is possible and propose that there is a buffer zone in the crystal structure of 1,4-dihydropyridines that governs the solid-state photodimerization process. This is exemplified by the fact that dimethyl l,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)pyridine-3,5-dicar-boxylate 83 cannot undergo solid-state photodimerization (Equation 21), whereas the structurally related (4/ 3, l / 3 )-methyl-l-phenyl-2-piperidinoethyl-l,4-dihydro-2,6-dimethyl-4-(2-thienyl)pyridine-3,5-dicarboxylate 84 affords a single product 5 (Scheme 2). Interestingly, when the photodimerization conditions are applied to the corresponding solution-phase reaction, the sole product is that of aromatization giving product 85. 

In poly[2,5-bis(3,4-ethylene-dioxy-2-thienyl)pyridine], a copolymer of thiophene and pyridine in a 2 1 ratio, the effective HOMO and LUMO energy levels of the ir-system are controlled in such a way that both p-doped and n-doped states are accessible (Scheme 9) [43]. The thin fdms display multicolor... 

In this article the results of a detailed optical spectroscopic investigation of a series of related bis-cyclometalated Rh3+ and Ir3 + complexes of the general formula [M(CnN),NnN]+, M = Rh3+, Ir3+ (HCnN = 2-phenylpyridine or 2-(2-thienyl) pyridine NnN = 2,2 -bipyridine or ethylenediamine) are summarized. The nature of the lowest excited states of the compounds is... 

Recently, a similar deuterium isotope effect was noted for 3-(3,-thienyl) pyridine (Bouwhuis and Janssen, 1972). In acid solutions in which the B and BH+ forms both fluoresce, the ratio of the... 

Tin(IV) coordinates 2-thienyl pyridine not through a [N,S] chelate but rather a [C,N] donor set, with activation of the proton on the 2-thienyl position, such as bis[3-(2-pyridyl)-2-thienyl]Ph2Sn, (154)." ... 

Reaction of trithiocyanuric acid with appropriate metal salts (PdClj, AgNOj) yields co-ordinated polymers of type [Pd3(C3N3S3)2]. I.r. spectra indicate that the ligand is N,S-co-ordinated in the aromatic form (20). Complexes of 2-(2 -thienyl) pyridine (=TP) with Pd, Pt have been reported (see p. 374). [Pd(TPXTP — HXNO,)] has one unidentate N-bonded TP group with the (TP —H) group N,C-chelated. 

Cyclometallated complexes with ruthenium and with other metals have also been synthesized [61] with 2-(2-thienyl)pyridine and with 2-(3-thienyl)pyridine. The Ru complexes reported had, however, halide and phosphine ligands coordinated to the central atom, which render these species unsuitable for photochemical considerations. Here again, a rather interesting family of compounds can be expected if the cyclometallated moieties are combined with other suitable ligands. 

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