Rhenium tricarbonyl complexes of tris(pyrazolyl)methane ligands: first structural characterization of an isomer pair of tris(pyrazolyl)methane derivatives and the supramolecular structure of the homobimetallic complex {1,4-C6H4[CH2OCH2C(pz)3]2[Re(CO)3]2}(

The reaction of either HC(pz)3, HC(3,5-Me2pz)3, HC(3-Phpz)3, or a 4:1 HC(3-i-Prpz)3–HC(3-i-Prpz)2(5-i-Prpz) mixture (pz=pyrazolyl ring) and Re(CO)5Br results in the formation of {[HC(pz)3]Re(CO)3}Br (1), {[HC(3,5-Me2pz)3]Re(CO)3}Br (3), {[HC(3-Phpz)3]Re(CO)3}Br (4), {[HC(3-i-Prpz)3]Re(CO)3}Br (5), and {[HC(3-i-Prpz)2(5-i-Prpz)]Re(CO)3}Br (6). The reaction of PhC(pz)2(py) (py=pyridyl ring) and Re(CO)5Br yields {[PhC(pz)2(py)]Re(CO)3}Br (9) while a reaction of Re(CO)5Br and 1,4-C6H4[CH2OCH2C(pz)3]2 in a 2:1 mol ratio gives {1,4-C6H4[CH2OCH2C(pz)3]2 [Re(CO)3]2}(Br)2 (10). The reaction of Re(CO)5Br and AgBF4 followed by addition of either HC(pz)3 or the 4:1 HC(3-i-Prpz)3–HC(3-i-Prpz)2(5-i-Prpz) mixture results in the preparation of {[HC(pz)3]Re(CO)3}BF4 (2), {[HC(3-i-Prpz)3]Re(CO)3}BF4 (7), and {[HC(3-i-Prpz)2(5-i-Prpz)]Re(CO)3}BF4 (8), respectively. The carbonyl stretching frequencies in all of these complexes are similar, with the exception of 9, which has much lower values. The methine hydrogen atoms of compounds 1, 5, and 6 show deshielded chemical shift values as a result of hydrogen-bonding interactions with the bromide counterion. The solid state structures of the isomeric pair 5 and 6 have very similar bond angles and distances about the metal and show weak hydrogen-bonding interactions between the Br− anion and the methine hydrogen. The structure of the bimetallic complex, 10, in which two [Re(CO)3]+ units are linked by the bitopic ligand, is organized by π–π and (C)H⋯π interactions into a two-dimensional supramolecular network of two interpenetrating ‘zigzag’ chains.