| The reaction of (C5R5)2ZrR' 2 with [Ph3C][B(C6F5) 4] in C6D5Cl affords [(C5R5) 2ZrR'(ClC6D5)][B(C6 F5)4] (1-d 5: R' = CH2Ph, (C5R 5)2 = (C5H5)2; 2a--d -d5: R' = Me; (C 5R5)2 = rac-(1,2-ethylene-bis-indenyl) (a), (C5H5)2 (b), (C5H4Me)2 (c), (C5Me 5)2 (d, C5Me5 = Cp*)). 1 and 2b,c are thermally robust but are converted to [{lcub}(C 5R5)2Zr(mu-Cl){rcub}2][B(C6F 5)4]2 (4b,c) by a photochemical process. In contrast, 2d undergoes ortho C-H activation to yield [Cp* 2Zr(eta2-C,Cl-2-ClC6H 4)][B(C6F5)4] (5), which slowly rearranges to [(eta4,eta1-C 5Me5C6H4)Cp*ZrCl][B(C6F 5)4] (6) via beta-Cl elimination and benzyne insertion into a Zr-CCp* bond. The higher thermal reactivity of 2d versus 1 and 2b,c is attributed to steric crowding of the Cp* ligand.; The methyl complexes (C5R2)2ZrMe(ClC 6D5)+ (C5R5 = Cp ( 1a), Cp' (1b)) react with PhSiH 3 to produce {lcub}(C5R5)2Zr(mu-H){rcub} 22+ (4a,b) and PhMeSiH2 as initial products via four-center Zr-C/Si-H sigma-bond metathesis transition states in which Si is beta to Zr. In contrast, the azazirconacycle Cp2Zr{lcub}eta 2(C,N)-CH2CHMe(6-methyl-2-pyridyl){rcub} + (3) and the pyridyl complex rac-(EBI)Zr{lcub}eta 2(C,N)-(6-phenyl-2-pyridyl){rcub}+ ( 6) react with PhSiH3 via transition states in which Si is alpha to Zr. Steric factors may determine the selectivity of these reactions.; The reactions of acrylonitrile (AN) with "L2PdMe +" species were investigated; (N^N = CH2(N-Me-imidazol-2-yl)2 (a, bim), ( p-tolyl)3CCH(N-Me-imidazol-2-yl) 2 (b, Tbim), CH2(5-Me-2-pyridyl)2 (c, CH2py'2), 4,4 '-Met-2,2'-bipyridine (d), 4,4'-tBu2-2,2' -bipyridine (e), (2,6-iPr2-C 6H3)N = CMeCMe = N(2,6-iPr2-C 6H3) (f). [(N^N)PdMe(NMe2Ph)][B(C6F5)4] (2a--c) and [{lcub}(N^N)PdMe{rcub}2(mu-Cl)] [B(C6F5)4] (2d--f ) react with AN to form N-bound (N^N)Pd(Me)(NCCH = CH2)+ (3a--f). 3a--e undergo 2,1 insertion to yield (N^N)Pd{lcub}CH(CN)Et{rcub}+, which form aggregates [(N^N)Pd{lcub}CH(CN)Et{rcub}]nn+ (n = 1--3, 4a--e) in which the Pd units are proposed to be linked by PdCHEtCN---Pd bridges. 3f does not insert AN at 23°C. 4a--e were characterized by NMR, ESI-MS, IR and derivatization to (NN)Pd{lcub}CH(CN)Et{rcub}(PR3)+ (R = Ph (5a--e), Me (6a--c)). 4a,b react with CO to form (NN)Pd{lcub}CH(CN)Et{rcub}(CO)+ (7a,b). 7a inserts CO slowly and reversibly to yield (bim)Pd{lcub}C(= O)CH(CN)Et{rcub}(CO)+ (8a).; (P^P)PdMeCl (1, a = (C6H5)2P(CH2)3P(C6H5)2 = dppp; b = Me2P(CH2)2PMe 2 = dmpe) react with [Li(Et2O)2.8][B(C6F 5)4] and excess AN to generate (P^P)Pd(Me)(NCCH = CH2)+ (3a,b). 3a does not insert AN at 23°C. 3b inserts AN to generate insertion products 4b. Zwitterionic {lcub}Ph2B(CH2PPh2) 2{rcub}Pd(Me)(NCCH = CH2) (3c) undergoes 2,1 insertion of AN to yield insertion species 4c. The structures of 4b,c have not been established. 4b reacts with PPh 3 to form (dmpe)Pd{lcub}CH(CN)Et{rcub}(PPh3)+ ( 5b). 4c react with PMe3 or C5H 5N to 4c generate (Ph2BP2)Pd{lcub}CH(CN)Et{rcub}(L) (6c, 7c) species. Anionic ligand c promotes AN insertion by favoring the pi-complex. |
