Synthesis and structural characterization of face-sharing bioctahedral complexes containing poly(pyrazolyl)borate ligands: [HB(Me 2Pz) 3BH][X 3Mo(μ-X) 2(μ-H)MoTp] (X=Cl or Br; Tp=HB(Me 2Pz) 3; Pz=pyrazolyl)

• Published in: Inorganica Chimica Acta Vol. 292; no. 2; pp. 182 - 188
• Main Authors: Lee, Chen-Long, Wu, Ying-Yann, Wu, Chi-Phi, Chen, Jhy-Der, Keng, Tai-Chiun, Wang, Ju-Chun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.09.1999
• Subjects: Bioctahedral complexes; Crystal structures; Molybdenum complexes; Poly(pyrazolyl)borate complexes; Crystal structures; Poly(pyrazolyl)borate complexes; Bioctahedral complexes; Molybdenum complexes
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/S0020-1693(99)00187-5

From a solution prepared by reaction of Mo 2(O 2CCH 3) 4 with KTp* (Tp*=hydridotris(3,5-dimethylpyrazolyl)borate, HB(Me 2Pz) 3), in glyme at room temperature, followed by addition of (CH 3) 3SiCl and (CH 3) 3SiBr to the red solution in refluxing THF, brown [HB(Me 2Pz) 3BH][Cl 3Mo(μ-Cl) 2(μ-H)MoTp*] ( 1), and [HB(Me 2Pz) 3BH][Br 3Mo(μ-Br) 2(μ-H)MoTp*] ( 2), respectively, can be prepared. A pink product [HB(Me 2Pz) 3BH][MoBr 4(Me 2PzH) 2] ( 3), was also obtained during the preparation of 2. Their structures have been determined by X-ray crystallography. The anions of complexes 1 and 2 consist of two octahedra sharing a common triangular face, so that the Mo atoms are bridged by one H and two halogen atoms. The unsymmetrical metal centers are also chelated by tridentate Tp* ligands and coordinated by three halogen atoms. In contrast to the symmetrical [Mo 2X 8H] 3− (X=Cl, Br or I) ions whose MoMo distances are hardly affected by the change in the size of the bridging halide atom, the variation of the MoMo distance from 1 to 2 is approximately 0.040 Å. The formation of the cation [HB(Me 2Pz) 3BH] + and the anion [MoBr 4(Me 2PzH) 2] − shows the ready BN bond cleavage of the Tp* ligand.