Discrete dinuclear and polymeric copper(I) cations bridged by 4,4'-bipyridine, trans-1,2-bis(4-pyridyl)ethene or bis(4-pyridyl) disulfide

Treatment of an acetonitrile solution of copper(I) tetrafluoroborate and 4,4'-bipyridine (4,4'-bipy) with 2-cyanoguanidine (cnge) yielded [{Cu(cnge)(2)}(2)(mu-4,4'-bipy)][BF4](2) . MeCN 1. Structural analysis revealed a planar dinuclear cation containing two, three-co-ordinate T-shaped copper centres bridged by 4,4'-bipy and terminally co-ordinated by two cnge molecules. In the absence of cnge but with an excess of copper(I), the product was [Cu(4,4'-bipy)(MeCN)(2)]BF4 2, structural analysis of which revealed a one-dimensional polymeric cationic zigzag chain, based on tetrahedral copper(I) atoms bridged by 4,4'-bipy and terminally co-ordinated by two MeCN molecules. The same reaction mixture but with an excess of 4,4'-bipy gave [Cu(4,4'-bipy)2]BF4 . MeCN 3. The corresponding trans-1,2-bis(4-pyridyl)ethene (bpe) systems yielded the analogous [{Cu(cnge)(2)}(2)(mu-bpe)][BF4](2) . 6MeCN 4, [Cu(bpe)(MeCN)(2)]BF4 5 and [Cu(bpe)(2)]BF4 6, respectively. Only one product has been isolated from the corresponding bis(4-pyridyl) disulfide (bpds) systems, [Cu(bdps)(MeCN)(2)]BF4 7. Attempts to produce copper(I) derivatives of 3,6-bis(imidazolyl)pyridazine (bimpydz) were unsuccessful, the copper(II) product, Cu(bimpydz)(MeCN)(2)(BF4)(2) 8, invariably being formed. Whereas the [{Cu(cnge)(2)}(2)(diimine)](2+) and [Cu(diimine)(MeCN)(2)](+) cations reacted with NOBF4 and NBu(4)(t)NO(2) forming copper(II) oxidation products, the [Cu(diimine)(2)](+) cations were unreactive.