The reaction of bis (3,5-dimethyl-1,2,4-triazol-1-yl) methane, CH2 (3,5-Me2Tz) 2, with M (CO) 6 (M=Cr, Mo or W) in refluxingDME produces CH2 (3,5-Me2Tz) 2M (CO) 4 in moderate yield. The crystal structures determined by X-ray analysis show thatbis (3,5-dimethyl-1,2,4-triazol-1-yl) methane acts as a chelating bidentate ligand with two endodentate nitrogen atoms in thesecomplexes. Reactions of complexes CH2 (3,5-Me2Tz) 2M (CO) 4 (M=Mo or W) with R2SnX2 (R=Ph or Me; X=Cl or Br) in a1:1 or 1:2 ratio, respectively, only yield 1:1 adducts. In these adducts, bis (3,5-dimethyl-1,2,4-triazol-1-yl)methane may coordinateto tin atom through exodentate nitrogen atoms on the 4-position of triazole rings to form linkage coordination polymers. Possiblyowing to weak donors of 4-position exonitrogen atoms on triazole rings to organotin acceptors, the dissociation of these adductsin solution could exist. Adduct of CH2 (3,5-Me2Tz) 2W (CO) 4

A series of new bis (pyrazol-1-yl)methane ligands with organogermyl and organosilyl groups on the methine carbon, MCHPz2(M/Ph3Ge, PhMe2Si, iPr3Si or Me3Si; Pz/3,5-dimethylpyrazole or 3,4,5-trimethylpyrazole), have been prepared by the reactionof bis (pyrazol-1-yl) methyllithium with triphenylgermanium bromide and organosilyl chloride. Treatment of these ligands withW (CO) 5 (THF) in refluxing THF resulted in new heterobimetallic complexes MCHPz2W (CO) 4 as major products, accompanied bypartial decomposition of ligands to yield a certain amount of PzW (CO) 5as by-products. These new ligands and complexes have beencharacterized by 1H-NMR, IR and elemental analysis. The molecular structures of complexes Ph3GeCHPz2W (CO) 4andMe3SiCHPz2W (CO)4 (Pz/3,5-dimethylpyrazole) have been determined by X-ray structure analysis, indicating that bis (pyrazol-1-yl)methanes act as chelating bidentate ligands in these complexes, and organometallic groups lie in the axial position of themethine carbon. # 2002 Elsevier Science B. V. All rights reserved.

Treatment of triarylstannyl-bis (3,4,5-trimethylpyrazol-1-yl) methane, Ar3SnCH (3,4,5-Me3Pz)2 (Ar) phenyl or p-tolyl), with W (CO) 5THF results in the oxidative addition of the tin-carbon (sp3) bond to the tungsten (0) center to yield the heterodinuclear complexes CH (3,4,5-Me3Pz) 2 (CO) 3W-SnAr3, in which four-membered metallacycles are found and bis (3,4,5-trimethylpyrazol-1-yl) methide acts as a tridentate monoanionic 3-[N,C,N] chelating ligand. purity synthetic methods for poly (pyrazol-1-yl) alkanes have been explored. 5b, 7 In recent years, modification of the central carbon atom by the organic functional groups to form heteroscorpionate ligands has also been successful. These new heteroscorpionate ligands usually have asymmetric N2O, 8N2S, 9or N3O10 coordination environments. Recently, replacement of the central carbon atom by the silicon atom to form poly (pyrazol Poly (pyrazol-1-yl) alkanes were first reported to form transition-metal complexes by Trofimenko in 1970.1 After that, and especially after an improved synthetic method was developed by Julia et al.,2 the coordination chemistry of these ligands has received increasing attention. 3, 4 A number of main-group5 and transitionmetal6 complexes containing poly (pyrazol-1-yl) alkanes have been synthesized and characterized in recent years. To advance the development of poly (pyrazol-1-yl) alkane chemistry, some new higher yield and higher