Synthesis and crystal structures of the novel tetrameric nitrido complexes [{cyelo-ReN}(4)(S2CNEt2) (6)(MeOH)(2)(PPh3)(2)][BPh4](2.).CH2Cl2.2H(2)O and [{cyclo-ReN}(4)(S2CNEt2)(4)Cl-4(PMe2Ph)(4)].2 acetone

摘要

Novel tetrameric rhenium(V) complexes have been prepared from [ReNCl2(PPh3)(2)] and [ReN(PMe2Ph).(S2CNEt)(2)], respectively. [ReNCl2(PPh3)(2)] reacts with 1.5 equivalents of KS2CNEt2 in methanol to yield the unusual dark red species [{cyclo-ReN}(4)(S2CNEt2)(6)(MeOH)(2).(PPh3)(2)][BPh4](2). CH2Cl2. 2H(2)O (1). The crystal structure of the tetramer (triclinic, space group P (1) over bar, a = 13.842(2), b = 15.213(2), c = 16.796(3) Angstrom, alpha = 67.88(1), beta = 70.90(1), gamma = 88.05(1)degrees, U = 3080.2(8) Angstrom(3), Z = 1) shows four rhenium atoms in a square configuration which are bridged via linear asymmetric Re=N-Re groups with bond lengths of about 169 and 203 pm. The molecule contains a centre of symmetry with two distinct octahedral rhenium environments. The first rhenium environment contains two bidentate dithiocarbamate ligands which complete the octahedral geometry and the second contains a bidentate dithiocarbamate ligand, coordinated methanol and has retained a single phosphine coligand. A symmetric compound containing the {cyclo-ReN}(4) core is obtained from the reaction of [ReN(PMe2Ph)(S2CNEt2)(2)] with Al2Cl6 in acetone. [{cyclo-ReN}(4)(S2CNEt2)(4)Cl-4.(PMe2Ph)(4)]. 2 acetone (2) forms red crystals (monoclinic, space group C2/c, a = 21.432(6), b = 13.700(3), c = 28.060(9) Angstrom, beta = 102.37(1)degrees, U = 8048(4) Angstrom(3), Z = 4) with each rhenium atom coordinated by a bidentate dithiocarbamato, a phosphine and a chloro ligand. The non-planar 8-membered {ReN}(4) ring contains asymmetric Re=N-Re bridges (mean values: 1.69 Angstrom and 2.029 Angstrom, respectively). In contrast, reaction of [ReNCl(S2CNEt2)(PMe2Ph)(2)] with one equivalent of K[S2CN(Me)CH2CH2NMe3]I gave the mixed dithiocarbamato-cation [ReN(S2CNEt2).(S2CN(Me)CH2CH2NMe3)(PMe2Ph)](+) (3) which was isolated as a tetraphenylborate salt. [References: 19]