Complexes based on the anionic octahedral rhenium chalcogenide clusters and [M(En)2]2+ (M = Ni, Cu) cations

Abstract

2641 The chemistry of octahedral rhenium cluster com plexes with the {Re 6 Q 8 } 2+ cores (Q = S, Se, Te) is being vigorously developed [1][2][3][4][5][6][7]. Some complexes obtained from elements by high temperature ampoule synthesis, for example, Re 6 Q 8 X 2 (Q = S, Se; X = Cl, Br) [8][9][10][11] or Re 6 Te 15 [12], are characterized by cova lent bonding between the clusters, i.e., they have poly meric structure. However, of most interest are the molecular and ionic cluster complexes that can be generally described as [{Re 6 Q 8 }L 6 ] n , where L is an inorganic or organic ligand [13][14][15][16][17][18][19][20][21]. The interest in these complexes is due to their properties such as sol ubility, high stability against thermal and chemical treatments, the possibility of variation and modifica tion of the ligand environment and redox transforma tions, long lived luminescence in the solid state and in solutions, and so on. In addition, when ligands (L) contain free donor atoms, the complexes [{Re 6 Q 8 }L 6 ] n can be used as nano sized building blocks for the syn thesis of coordination polymers with different metal cations. This feature was clearly demonstrated, for example, in a series of works describing the cyano bridged polymers of different dimensionality com posed of anionic chalcocyanide complexes [Re 6 Q 8 (CN) 6 ] 4-/3-(Q = S, Se, Te) and various transi tion metal cations [22][23][24][25][26][27].We proposed an original method for the synthesis of chalcohydroxo complexes [Re 6 Q 8 (OH) 6 ] 4-(Q = S, Se) consisting in the reaction of known polymeric complexes Re 6 Q 8 X 2 (Q = S, Se; X = Cl, Br) with mol 1 Dedicated to Professor Vladimir Fedorov on the occasion of his 75th birthday. ten KOH or CsOH [28, 29]. These complexes proved to be convenient precursors for ligand exchange reac tions, because apical OH ligands are replaced rather easily by other ligands, for example, by carboxylate anions [30, 31]. In addition, it was shown that the complexes [Re 6 Q 8 (OH) 6 ] 4-are coordinated to alka line earth metal cations to give polymeric structures [32]. The question arises of whether polymers of this type could be obtained based on the [Re 6 Q 8 (OH) 6 ] 4-anions and transition metal cations similarly to the case of rhenium chalcocyanide cluster complexes [22, 23, 26]. This study deals with the reactions of the anionic cluster complexes [Re 6 Q 8 (OH) 6 ] 4-(Q = S, Se) with the cationic complexes [M(Еn) 2 ] 2+ (M = Ni, Cu) in aqueous solutions. Three new compounds, [Ni(H 2 O) 2 (Еn) 2 ][{Ni(Еn) 2 }Re 6 S 8 (OH) 6 ] ⋅ 7H 2 O (I), [{Cu(En) 2 }Re 6 S 8 (H 2 O) 2 (OH) 4 ] · 4H 2 O (II), and [Ni(H 2 O) 2 (En) 2 ] 0.5 [Re 6 Se 8 (H 2 O) 3 (OH) 3 ] ⋅ 10H 2 O (III), were thus obtained and structurally characterized. EXPERIMENTAL The initial complexes K 4 [Re 6 Q 8 (OH) 6 ] ⋅ 8H 2 O were prepared by a reported procedure [28]. The ratio of heavy elements was determined by energy dispersive X ray analysis (EDAX) using a JSM 6700F raster electron microscope. The elemental analysis for C, H, N, and S was carried out on...

New mixed-ligand cyanohydroxo octahedral cluster complex trans-[Re6S8(CN)2(OH)4]4−, its luminescence properties and chemical reactivity

“…The rst example is the aquahydroxo complex [{Cu(en) 2 }Re 6 S 8 (H 2 O) 2 (OH) 4 ]$4H 2 O (en ¼ ethylenediamine) which was obtained by reaction of [Re 6 Se 8 (OH) 6 ] 4À with Cu(en) 2 Cl 2 in water. 8 In this case the square-planar geometry of the {Cu(en) 2 } 2+ moiety is formed by en nitrogen atoms, and the coordination environment of Cu(II) center is completed to an octahedral by two sulfur atoms of the cluster complexes. The reaction of [Re 6 S 8 (OH) 6 ] 4À with Cu 2+ in an aqueous ammonia yielded the second example, [{Cu(NH 3 ) 3 } 2 {Re 6 S 8 (OH) 6 }]$8H 2 O, where the octahedral coordination environment of Cu(II) center includes three ammine nitrogen atoms, one hydroxo oxygen and two sulfur atoms originating from two different cluster anions.…”

“…This strategy was used, for example, for the preparation of chalcocyanide complexes [Re 6 Q 8 (CN) 6 ] 4À (Q ¼ S, Se, or Te) and chalcohydroxo complexes [Re 6 Q 8 (OH) 6 ] 4À (Q ¼ S, Se) by the reactions of the corresponding cluster polymers with molten KCN 4 or MOH (M ¼ K or Cs), 5 respectively. In chalcocyanide complexes CN groups, due to their ambidentate character, can serve as bridging ligands between cluster cores and transition metal cations to give polymeric compounds in different dimensionalities, 6 while chalcohydroxo ones can be used both as building blocks for preparation of OH-bridged compounds with alkaline-earth 7 and transition metal cations, 8 and as precursors for preparation of new hexarhenium cluster complexes by substitution of relatively labile OH groups by various organic and inorganic ligands. 1b,9 Recently, a number of compounds containing mixed-ligand cyanohydroxo complexes trans-[Re 6 Q 8 (CN) 4 -(OH) 2 ] 4À (Q ¼ S, Se) have been prepared and characterized.…”