Copper−Selenium Interactions: Influence of Alkane Spacer and Halide Anion in the Synthesis of Unusual Polynuclear Copper(I) Complexes with Bis(diphenylselenophosphinyl)alkanes

• Published in: Inorganic chemistry 2003-07, Vol.42 (15), p.4731-4737
• Main Authors: Lobana, Tarlok S, Rimple, Castineiras, Alfonso, Turner, Peter
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic034010n

The reactions of copper(I) halides with bis(diphenylselenophosphinyl)alkanes, namely Ph2P(Se)−(CH2) n −P(Se)Ph2 {n = 1−4}, in acetonitrile are described. The ligand 1,3-bis(diphenylselenophosphinyl)propane {dppp-Se,Se} with copper(I) bromide and copper(I) iodide formed two unusual infinite coordination polymers, namely {Cu2Br2(μ2-dppp-Se−Se)2} n , 1, and {Cu3I3(μ2-dppp-Se,Se)2} n , 2. Selenium bridged dinuclear complexes, [Cu2Br2((μ3-dppm-Se,Se)2], 3, and [Cu2I2(dppm-Se,Se)2], 4, were formed using 1,1-bis(diphenylselenophosphinyl)methane {dppm-Se,Se}. Similarly, 1,2-bis(diphenylselenophosphinyl)ethane {dppe-Se,Se} and 1,4-bis(diphenylselenophosphinyl)butane {dppb-Se,Se} formed complexes, Cu2Br2(dppe-Se,Se)2, 5, and Cu2I2(dppb-Se,Se), 6. These have been characterized with the help of analytical data, infrared spectroscopy, and, for compounds 1−3, X-ray crystallography. Compound 2, {Cu3I3((dppp-Se,Se)2} n , has two dppp-Se,Se molecules coordinating to two copper(I) atoms of the dinuclear Cu(μ-I)2Cu core in unidentate fashion, with two pendant Ph2P(Se)− moieties in trans orientation, and one of these groups is coordinated to another copper(I) iodide moiety, thus forming the repeat unit (A), −CuI(μ-dppp-Se,Se)Cu(μ-I)2Cu(μ-dppp-Se,Se)−. This repeat unit (A) combined with another unit, and this process continued and finally formed the infinite polymer 2. In this polymer, the mononuclear CuISe2 and dinuclear Cu2(μ-I)2Se2 cores have distorted trigonal planar geometries around Cu centers. The Cu(2)···Cu(2)* separation of 2.643(1) Å is less than twice the van der Waals radius of Cu, 2.80 Å. The structure of polymer 1 is similar to that of 2, except that it has only mononuclear trigonal planar CuBrSe2 units bridged by Se atoms of dppp-Se,Se ligand, and the repeat unit is −CuBr(μ2-dppp-Se,Se)CuBr(μ2 -dppp-Se,Se)−. The formation of zigzag one-dimensional copper(I) coordination polymers (1 and 2), with trigonal planar copper(I) centers, provides the first examples of this type in tertiary phosphine chalcogenide chemistry. In contrast, the decrease in methylene chain length, from −(CH2)3− to −(CH2 )−, resulted in chelation by the dppm-Se,Se ligand, forming CuBr(dppm-Se,Se), which dimerized via Se donor atoms and formed [Cu2Br2(μ3-dppm-Se,Se)2], 3. It has a relatively less common central kernel, Cu(μ-Se)2Cu, and each Cu atom is further bonded to one terminal Br and one Se atoms, and the geometry around each Cu center is distorted tetrahedral (bond angles, ca. 101−121°).