Tris borato complex

M[pzTp](H20) (M = Na, K) have been determined by x-ray diffraction (30). In contrast to the discrete monomeric structures of the tris (pyrazolyl)hydroborato complexes Tl[TpRR ], K[TpBut2], and Cs[TpBut2] described earlier, the hydrated tetrakis(pyrazolyl)borato complexes M[PzTp](H20) (M = Na, K) exhibit an interesting polymeric-type structure, a portion of which is illustrated in Fig. 14. In each case, the cations occupy two different crystallographic sites, and the cation in one of the sites is coordinated to two pyrazolyl groups in a rr-type fashion. 

Group III Donors. Boron donor ligands. The unusual tris(pyrazolyl)borato-complex [RuL3(CO)2X] [X = Cl, Br, or I L = (16a)] has been prepared ... 

Figure 8.2. Silver tris(pyrazolyl)borato complexes.

The six-coordinate, coordinatively unsaturated nitrosyl tris(3,5-dimethylpyrazolyl)borato complexes [Mo(NO) HB(3,5-Me2pyz)3)XY], where X = Y = Cl or I X = Cl or I, Y = OR, OAr, NHR, NHAr, etc) are redox active, undergoing a one-electron reduction to form the paramagnetic monoanionic species [Mo(NO) HB(3,5-Me2pyz)3XY] . The neutral precursor formally contains a metal atom having a 16-electron configuration, whereas the metal in the reduced species has a 17-electron configuration. 

The relative orientations of these groups in the dicarbonyl [Mo(CX))2(NO)L"] are similar but have no apparent steric consequences. It is not possible to make a direct structural comparison with phenolate complexes of other tris(pyrazolyl)borato complexes, but this strong orientational effect is absent in the formally isoelectronic anilido species [Mo(NO) HB(3,5-Me2pyz)3)I(NHC R-p)] (R = Me or OMe)4. Certainly other work has indicated that orientational effects can have a pronounced effect on reduction potentials in these systems. ... 

Kinetics studies have demonstrated that the isomerization is a first-order process, characterized by the activation parameters AH% = 34.5(8) kcal mol-1 and A St = 6(2) e.u. Such rearrangements of poly-(pyrazolyl)borato ligands are not uncommon, and have also been observed for Cu and Co complexes of the tris(3-isopropylpyrazolyl)hydro-borato ligand system, i.e., [T73-HB(3-Pr pz)3]M — [T73-HB(3-Pr1pz)2(5-Pr pz)]M (32). 

Silver(I) complexes are known with the tris(pyrazolyl)borate [HB(pz)3] and the methyl, phenyl, bromo, or trifluoromethyl-substituted derivatives. The structure of the silver tri(pyrazolyl)borato species has been a puzzle since it was first reported.385,386 It was suggested that the structure could be oligomeric, but recently the crystal structure of the compound [Ag HB(3,5-Me2pz)3 ]2 shows that it has a dimeric structure387 where the silver(I) centers are tricoordinated by a bidentate arm of one ligand and a monodentate arm of the other ligand (29). The related complexes [Ag HB(4-Brpz)3 ]2, [Ag HB(4-Mepz)3 ]2, [Ag HB(3,5-Me2pz)3 ]2, [Ag HB(3-Mepz)3 ] , [Ag B(pz)4 ], and... 

Figure 1 shows the molecular structure of the ferrocenyl-tris(pyrazo-lyl)borato-Mo(II) complex [( -C5H5)Fe 5-C5H4-(Tp)Mo(Co)2(CHr C(Me) = CH2) ].3... 

Figure 6 shows the electrochemical behaviour of the diferrocenyl-bis[tris(pyrazolyl)borato]-Fe(II) derivative there schematized, strictly related to the previous complexes.3... 

Experimental Procedure 3.1.4. Preparation of a Molybdenum Vinylidene Complex from a Carbyne Complex Tetrabutylanunoniuih Cyano(ethoxycarbonyl) vinylidene (dicarbonyl) hydro-tris(3,5-dimethyl-1 -pyrazblyl)borato molybdenum [526] [37] pp 151 and 188... 

One of the chlorides in this complex can be exchanged for perchlorate on treatment of a solution of the complex in dichloromethane/acetonitrile with silver perchlorate2. Dicarbonyl(chloromethylidyne)[hydrotris(pyrazol-l-yl)borato]molybdenum(IV) reacted with sodium telluride in aqueous methanol to produce the anionic dicarhonyl[hydro-tris(pyrazol-l-yl)borato telluracarbonylmolybdate(0), which was isolated as the moderately air-stable tetraethylammonium salt. This salt reacted with methyl iodide in acetonitrile to form dicarbonyl[hydrotris(pyrazolo)borato](methyltelluromethylidyne) molybdenum(IV)3. 

Tris(pyrazolyl)borato and Related Triaza Ligand Complexes... 

The cationic species [Mo(CO)2(NO)(R3tacn)]+, obtained by reaction of [Mo(CO)3(R3tacn)] with HNO3 or with NOBF4, could be converted into [Mo(NO)(R3tacn)X2]+ and [Mo(NO)(R3tacn)X(OR )]+, but these complexes did not exhibit the rich electrochemistry of their tris(pyrazolyl)borato analogues [Mo(NO)Tp X2] and [Mo(NO)Tp X(OR)]. 

Tris(pyrazolyl)borato and related cyclic triaza ligand complexes of the general class [Mo(NO)Tp XY], in which the metal adopts a formal oxidation state of 0,1, or II, have been described above in Section 5.6. 

A wide series of ferrocenyl-molybdenum complexes of known redox properties bear the tris(3,5-dimethylpyrazolyl)borato ligand or the N,iV, N"-trimethyl-l,4,7-triazacyclononane ligand. They are illustrated in Scheme 7-7 [55 — 59]. 

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