SYNTHESIS OF GROUP-4 COMPLEXES THAT CONTAIN THE TRIDENTATE DIAMIDO DONOR LIGANDS [(ARYLNCH(2)CH(2))(2)O](2-) AND ZIRCONIUM COMPLEXES THAT CONTAIN [(ARYLNCH(2)CH(2))(2)S](2-) AND AN EVALUATION OF THEIR ACTIVITYFOR THE POLYMERIZATION OF 1-HEXENE/

Compounds of the type (ArylNHCH(2)CH(2))(2)O (Aryl= 2,6-Me2C6H3 (H-2[1 a]), 2,6-Et2C6H3 (H-2[1b]), 2,6-i-Pr2C6H3 (H-2[1c])) can be prepared b y treating (TsOCH2CH2)(2)O (TsO = tosylate) with the lithium anilides in THF. [1a,b]TiCl2, [1a,b]TiMe2, [1a]Ti(CH2Ph)(2), [1a-c]M(NMe2)(2) ( M = Zr or Hf), [1a-c]MCl2, and [1a-c]MR2 (R = Me, Et, i-Bu) were prepa red. An X-ray study of [1aTi](CH2Ph)(2) revealed the structure to be a distorted trigonal bipyramid (type B) in which the two amido nitrogen s and one benzyl Ligand occupy equatorial positions. An X-ray study of [1a]ZrMe2 showed it to be a distorted trigonal bipyramid that contain s ''axial'' amido groups (type A), while an X-ray study of [1c]HfEt2 r evealed it to have a structure halfway between type A and type B, i.e. , a distorted square pyramid with one alkyl in the apical position. An alogous compounds were also prepared that contain a sulfur donor inste ad of oxygen, i.e., [(2,6-Me2C6H3NHCH2CH2)(2)S] (H-2[2a]), [(2,6-i-Pr2 C6H3NHCH2CH2)(2)S] (H-2[2c]), [2a,c]Zr(NMe2)(2), [Ba,c]ZrCl2, [2Ba,c]Z rMe2,and [2c]Zr(CH2CHMe2)(2). An X-ray study of [2a]-ZrMe2 revealed it to be closest to a type B structure. Addition of 1 equiv of [PhNMe2H] -[B(C6F5)(4)] in C6D5X (X = Br, Cl) to [1a,c]MMe2 (M = Zr, Hf) gave ca tionic complexes that contain coordinated dimethylaniline, with which free aniline does not exchange readily on the NMR time scale at 60 deg rees C. Addition of excess ether to {[1a]MMe(NMe2Ph)}[B(C6F5)(4)] (M = Zr, I-If) led to {[1a]MMe(ether)}[B(C6F5)(4)] (M = Zr, Hf) complexes in high yield. Analogous cations can be prepared in the sulfur ligand system, but they do not appear to be as stable as in the oxygen ligand system. Zr and I-If dimethyl complexes that contain an oxygen donor o r a sulfur donor ligand can be activated with [Ph3C][B(C6F5)(4)] to yi eld efficient catalysts for polymerization of l-hexene; although the m olecular weight of the poly(l-hexene) chains is limited to similar to 20 000 - similar to 25 000 under the conditions employed. Neither {[1c ]ZrMe-(ether)}[B(C6F5)(4)] nor {[1c]HfMe(ether)}[B(C6F5)(4)] will poly merize I-hexene in Ce6D6 Br at room temperature, and neither will poly merize ethylene readily at 1 atm and 25 degrees C. It is proposed that a solvated five-coordinate cation must lose the solvent in order to r eact with an olefin and that beta-hydride elimination in the four-coor dinate cation limits chain length.