Ancillary ligand effects in zirconium(IV)aminoborollide and nitrogen chelated platinum(II) complexes.

摘要

The preparation of new chloro derivatives of pentamethylcyclopentadienyl aminoborollide complexes of Zr are described. Treatment of the dianions 1.9--1.12 with Cp*ZrCl3 yields Cp*{eta5-C 4H4BN(Si(CH3)3)2}ZrCl·LiCl (1.13), Cp*{eta5-C4H4BNC(CH 3)3Si(CH3)3}ZrCl·LiCl ( 1.14), [Cp*{eta5-C4H4 BN(Et)CH2CH2NEt2}ZrCl2Li] 2 (1.15), and Cp*{eta5-2,5-Ph2C 4H2BNMe2}ZrCl·LiCl (1.16). The electronic spectra of these complexes were measured and compared to the parent complex Cp*{eta5-C4H4BN(CHMe 2)2}ZrCl·LiCl (1.17a) in THF solvent. In general, as the substituents directly bonded to nitrogen increase in size, a blue shift of the low energy, aminoborollide to zirconium charge transfer band (LMCT), occurs. lambdamax decreases in the order 1.16 > 1.17a > 1.14 > 1.15∼ 1.13. The anionic portions of complexes 1.13--1.16 have also been structurally characterized by x-ray crystallography. Although the changes are very small, in general a lengthened B--N bond correlates linearly with the observed blue shift of the LMCT band.;Studies directed towards the development of a Pt(II)-catalyzed oxidation of ethylene to ethylene glycol based on the Shilov system for alkane functionalization is described. The first system examined was the methyl ethylene complex [(tmeda)PtMe(eta 2-C2H4)][SbF6], 2.2. Nucleophilic attack at the bound ethylene was not observed; instead displacement of ethylene occurred. The bound ethylene in the neutral complexes cis-Cl2PtL(eta2-C2H4 ), (L = PPh3 (2.23), AsPh3 ( 2.24), Me2SO (2.25)) and trans-Cl 2Pt(eta2-C2H4)(C5H 5N), 2.26 are susceptible towards attack by OH- .;The dicationic complexes [(ArN=C(Me)--C(Me)=NAr)Pt(solv)2]X 2, (Ar = 2,6-(CH3)2C6H3; 3.5a: solv = CH3CN, X = CF3SO3 -, BF4-, SbF6 -, 3.5b: solv = (CH3)2CO, X = BF4-, SbF6-) and 3.6 [(CyN=C(H)--C(H)=NCy)Pt(CH3CN)2 ]X2, (Cy = C6H11, X = OTf- , BF4-, PF6- , SbF6-) were synthesized from the corresponding Pt dichlorides with 2 equiv. of AgX. The reaction of 3.5a with 1-phenylpyrazole, 2-phenylpyridine, 2-vinylpyridine, and 2-(2-thienyl)pyridine in acetone affords the cyclometalated products 3.11--3.14 via intramolecular C--H activation of an sp 2 C--H bond of the unsaturated sidegroup.;The diaqua complex [(ArN=C(Me)--C(Me)=NAr)Pt(H2O) 2]X2, 4.3, (Ar = 2,6-(CH3)2 C6H3; X = OTf-, BF4 -) decompose in aqueous solution to yield a red-orange precipitate. Spectroscopic characterization of the precipitate by 1H, IR, and conductivity measurements is consistent with C2v symmetric structure containing hydroxo groups. Confirmation of the dicationic, dinuclear Pt(II) complex, 4.4, where the two Pt centers are bridged by two OH groups was revealed by x-ray crystallography. (Abstract shortened by UMI.)