含R_2dtc配体和V=O基的金属簇红外光谱研究

Study on the Infrared Spectra of Metallic Clusters Containing R_2dtc Ligand and V=O Group

This paper reports the features and regularities of the infrared spectra for two kinds of complexes containing R 2dtc ligand. The cubane like clusters containing R 2dtc ligand possess weak and wide peaks at 400—500 cm -1 assigned to M μ 3S vibration,while the peaks at 330—380 cm -1 and 1 470—1 510 cm -1 can be assigned to M S dtc and C—N vibrations,respectively.The ν ( C—N ) and ν (C=S)  vibrations for Me 2dtc cubane cluster exhibit blue shift and red shift,respectively,when compared with those of other R 2dtc ones.This would be attributed to the strong super conjugation of the methly group. The M μ 3S vibrations for both types of complexes [V 2Cu 2S 4(R 2dtc) 2(PhS) 2] 2- and [VCu 4S 4(R 2dtc) n(PhS) 4-n ] 3- ( n =0,1,2) occur at 480 and 465 cm -1 ,respectively.This small difference becomes a useful indication to distinguish the two types of clusters. Cluster complexes containing (R 2dtc) 2V 2O 2(μ S) 2 structural unit show the V=O vibration in the range of 844—970 cm -1 .It is noted that (Et 4N)[V 3S 2O 3(Et 2dtc) 3] contains two sets of the V=O bonds corresponding to two sets of V=O vibrations at 970 and 844 cm -1 .An additional coordination of the V=O bond to another metal atom obviously weakens the V=O bond to give rise to the red shift of the infrared frequency.Similar red shifts were also observed for other complexes and were discussed.