TY - JOUR
T1 - Synthesis and structures of solvated monoclusters and bridged Di- and triclusters based on the cubic building block [Re6(μ3-Se)8]2+
AU - Zheng, Zhiping
AU - Gray, Thomas G.
AU - Holm, R. H.
PY - 1999
Y1 - 1999
N2 - The cluster formulated as [Re6Sc7(SeH)I6]3- has been previously shown to undergo ligand substitution reactions to generate the family [Re6Se8(PEt3)nI6-n] (n-4)+ (n = 3-6), several members of which form solvate clusters upon treatment with Ag(I) in acetonitrile. Here it is demonstrated that additional de-iodination reactions afford solvate clusters useful in building up bridged cluster arrays. In dichloromethane/solv (5:1 v/v) in the presence of 2 equiv of AgSbF6 at room temperature, trans-[Re6Se8(PEt3)4I2] forms trans-[Re6Se8(PEt3)4(solv) 2]2+ (solv = MeCN (5), DMF (6), Me2SO (7)). The hexaiodo cluster with 6 equiv of AgSbF6 gives the fully solvated clusters [Re6Seg-(solv)6]2+ (solv = DMF (9), Me2SO (10), py (11)). In refluxing chlorobenzene for 3 days, [Re6Se8(PEt3)5(MeCN)]2+ (1) and 4,4′-bipyridine (4,4′-bpy) yield [Re6Se8(PEt3)5(4,4′-bpy)] 2+ (12); similarly, cis- and trans-[Re6Se8(PEt3)4-(MeCN) 2]2+ afford the cis- and trans-14 isomers, respectively, of [Re6Se8(PEt3)4(4,4′-bpy) 2]2+. Clusters 1 and 12 (or 1 and 1/2 equiv of 4,4-bpy) under the same conditions afford the bridged dicluster {[Re6Se8(PEt3)5] 2(4,4′-bpy)}4+ (15). The related diclusters {[Re6Se8(PEt3)5] 2(L-L)}4+ (L-L = 4,4′-py2C2H2 (16), 4,4′-py2C2H4 (17) (4,4′-py2C2H2 = trans-l,2-bis(4-pyridyl)ethylene, 4,4′-py2C2H4 = trans-l,2-bis(4-pyridyl)ethane)) are obtained by analogous methods. Reaction of 14 and 2 equiv of 1 in refluxing dichloromethane produces the linear tricluster {[Re18Se24(PEt3) 14(4,4′-bpy)2}6+. All clusters were isolated as SbF6- salts in yields of ca. 60-90% and were characterized by their 1H and 31P NMR spectra and by mass spectrometry. In addition, the structures of 10 clusters (5-7, 9-12, 14-16) were confirmed by X-ray structure determinations. All clusters are based on the cubic [Re6(μ3-Se)8]2+ core whose dimensions are insensitive to the nature and substitution pattern of the ligands. All substitution reactions, as indicated, proceed with retention of stereochemistry. Appropriate choice of solvate cluster leads to the unambiguous formation of 14-17, and should allow the construction of these and other cluster array shapes with variable bridging ligands. On the basis of voltammetric and EPR properties, clusters originally described as the monoprotonated species [Re6Se7(SeH)I6]3- and [Re6S7(SH)Br6]3- are reformulated as the oxidized 23-electron clusters [Re6Se8I6]3- and [Re6S8Br6]3-.
AB - The cluster formulated as [Re6Sc7(SeH)I6]3- has been previously shown to undergo ligand substitution reactions to generate the family [Re6Se8(PEt3)nI6-n] (n-4)+ (n = 3-6), several members of which form solvate clusters upon treatment with Ag(I) in acetonitrile. Here it is demonstrated that additional de-iodination reactions afford solvate clusters useful in building up bridged cluster arrays. In dichloromethane/solv (5:1 v/v) in the presence of 2 equiv of AgSbF6 at room temperature, trans-[Re6Se8(PEt3)4I2] forms trans-[Re6Se8(PEt3)4(solv) 2]2+ (solv = MeCN (5), DMF (6), Me2SO (7)). The hexaiodo cluster with 6 equiv of AgSbF6 gives the fully solvated clusters [Re6Seg-(solv)6]2+ (solv = DMF (9), Me2SO (10), py (11)). In refluxing chlorobenzene for 3 days, [Re6Se8(PEt3)5(MeCN)]2+ (1) and 4,4′-bipyridine (4,4′-bpy) yield [Re6Se8(PEt3)5(4,4′-bpy)] 2+ (12); similarly, cis- and trans-[Re6Se8(PEt3)4-(MeCN) 2]2+ afford the cis- and trans-14 isomers, respectively, of [Re6Se8(PEt3)4(4,4′-bpy) 2]2+. Clusters 1 and 12 (or 1 and 1/2 equiv of 4,4-bpy) under the same conditions afford the bridged dicluster {[Re6Se8(PEt3)5] 2(4,4′-bpy)}4+ (15). The related diclusters {[Re6Se8(PEt3)5] 2(L-L)}4+ (L-L = 4,4′-py2C2H2 (16), 4,4′-py2C2H4 (17) (4,4′-py2C2H2 = trans-l,2-bis(4-pyridyl)ethylene, 4,4′-py2C2H4 = trans-l,2-bis(4-pyridyl)ethane)) are obtained by analogous methods. Reaction of 14 and 2 equiv of 1 in refluxing dichloromethane produces the linear tricluster {[Re18Se24(PEt3) 14(4,4′-bpy)2}6+. All clusters were isolated as SbF6- salts in yields of ca. 60-90% and were characterized by their 1H and 31P NMR spectra and by mass spectrometry. In addition, the structures of 10 clusters (5-7, 9-12, 14-16) were confirmed by X-ray structure determinations. All clusters are based on the cubic [Re6(μ3-Se)8]2+ core whose dimensions are insensitive to the nature and substitution pattern of the ligands. All substitution reactions, as indicated, proceed with retention of stereochemistry. Appropriate choice of solvate cluster leads to the unambiguous formation of 14-17, and should allow the construction of these and other cluster array shapes with variable bridging ligands. On the basis of voltammetric and EPR properties, clusters originally described as the monoprotonated species [Re6Se7(SeH)I6]3- and [Re6S7(SH)Br6]3- are reformulated as the oxidized 23-electron clusters [Re6Se8I6]3- and [Re6S8Br6]3-.
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U2 - 10.1021/ic9906050
DO - 10.1021/ic9906050
M3 - Article
AN - SCOPUS:0001741648
SN - 0020-1669
VL - 38
SP - 4888
EP - 4895
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 21
ER -