The titanocene silyl hydride complexes [Ti(Cp)2(PMe3)(H)(SiR3)] [SiR3=SiMePhCl (6), SiPh2Cl (7), SiMeCl2 (8), SiCl3 (9)] were prepared by HSiR3 addition to [Ti(Cp)2(PMe3)2] and were studied by NMR and IR spectroscopy, X-ray diffraction (for 6, 8, and 9), and DFT calculations. Spectroscopic and structural data established that these complexes exhibit nonclassical Ti-H-Si-Cl interligand hypervalent interactions. In particular, the observation of silicon-hydride coupling constants J(Si,H) in 6-9 in the range 22-40 Hz, the signs of which we found to be negative for 8 and 9, is conclusive evidence of the presence of a direct Si-H bond. The analogous reaction of [Ti(Cp)2(PMe3)2] with HSi(OEt)3 does not afford the expected classical silyl hydride complex [Ti(Cp)2(PMe3)(H)[Si(OEt)3]], and instead NMR-silent titanium (apparently TiIII) complex(es) and the silane redistribution product Si(OEt)4 are formed. The structural data and DFT calculations for the compounds [Ti(Cp)2(PMe3)(H)(SiR3)] show that the strength of interligand hypervalent interactions in the chlorosilyl complexes decreases as the number of chloro groups on silicon increases. However, in the absence of an Si-bound electron-withdrawing group trans to the Si-H moiety, a silane sigma complex is formed, characterized by a long Ti-Si bond of 2.658 A and short Si-H contact of 1.840 A in the model complex [Ti(Cp)2(PMe3)(H)(SiMe3)]. Both the silane sigma complexes and silyl hydride complexes with interligand hypervalent interactions exhibit bond paths between the silicon and hydride atoms in Atoms in Molecules (AIM) studies. To date a classical titanocene phosphane silyl hydride complex without any Si-H interaction has not been observed, and therefore titanocene silyl hydrides are, depending on the nature of the R groups on Si, either silane sigma complexes or compounds with an interligand hypervalent interaction.

Synthesis, reactions, and DFT studies of macrocycle-supported imido titanium alkyl cations derived from Ti(N t Bu)(Me 3 [9]aneN 3 )R 2 (R ) Me (1) or CH 2 SiMe 3 (2)) are described (Me 3 [9]aneN 3 ) 1,4,7trimethyltriazacyclononane). Reaction of 1 with 1 equiv of [Ph 3 C][BAr F 4 ] or BAr F 3 (Ar F ) C 6 F 5 ) in C 6 D 5 Br afforded the methyl cation [Ti(N t Bu)(Me 3 [9]aneN 3 )Me] + (6 + ), whereas with half an equivalent of [Ph 3 C][BAr F 4 ] the fluxional methyl-bridged homo-binuclear cation [Ti 2 (N t Bu) 2 (Me 3 [9]aneN 3 ) 2 Me 2 (µ-Me)] + (10 + ) was formed. Reaction of 1 with [Ph 3 C][BAr F 4 ] in CD 2 Cl 2 formed the monochloride cation [Ti(N t Bu)(Me 3 [9]aneN 3 )Cl] + (8 + ), which was also prepared from Ti(N t Bu)(Me 3 [9]aneN 3 )Cl(Me) and [Ph 3 C][BAr F 4 ]. Cation 8 + reacted with pyridine to give the adduct [Ti(N t Bu)(Me 3 [9]aneN 3 )Cl(py)] + (9 + ) and with Ti(N t Bu)(Me 3 [9]aneN 3 )Me 2 to form the chloride-bridged cation [Ti 2 (N t Bu) 2 (Me 3 [9]aneN 3 ) 2 -Me 2 (µ-Cl)] + (11 + ). Reaction of 2 with [Ph 3 C][BAr F 4 ] gave [Ti(N t Bu)(Me 3 [9]aneN 3 )(CH 2 SiMe 3 )] + (7 + ), which is stabilized by a β-Si-C agostic interaction characterized by a high-field-shifted 29 Si NMR resonance. Attempts to generate 7 + by reaction of 2 with [PhNMe 2 H][BAr F 4 ] in CH 2 Cl 2 led to Ti(N t Bu)(Me 3 [9]aneN 3 )Cl 2 and [PhNMe 2 (CH 2 Cl)][BAr F 4 ] (12-BAr F 4) via a series of solvent activation reactions, the details of which have been elucidated. Reaction of 6 + or 7 + with Ph 3 PO afforded the adducts [Ti(N t Bu)(Me 3 [9]aneN 3 )R(Ph 3 PO)] + , whereas with pyridine a C-H bond activation reaction occurred to give [Ti(N t Bu)(Me 3 [9]aneN 3 )(NC 5 H 4 )] + (17 + ) and the corresponding alkane RH. Density functional theory calculations of the isolobal d 0 fragments [Ti(NR)(R′ 3 [9]aneN 3 )] 2+ and [Cp 2 Ti] 2+ found that their frontier orbitals, although broadly similar, featured important differences in their shapes and energies. These account for the absence of any R-C-H agostic interaction in 6 + , whereas [Cp 2 TiMe] + is stabilized by a weak interaction of this type, as judged by DFT-computed geometries. The experimentally observed increase in Ti-Me group average 1 J CH on forming either 6 + from 1 or [Cp 2 TiMe] + from Cp 2 TiMe 2 is reproduced by DFT and attributed to intrinsic global changes in carbon 2s orbital contribution to the Ti-C and C-H bonds upon cation formation. These changes were shown to mask the otherwise expected decrease in average 1 J CH for the R-agostic methyl in [Cp 2 TiMe] + . The difference between the Ti-Me 1 J CH values in 1 (111 Hz) and isolobal Cp 2 TiMe 2 (124 Hz) was also attributed to differences in Ti center electrophilicity. The experimental high-field-shifted 29 Si NMR resonance in 7 + was well reproduced in the DFT-computed β-Si-C agostic structure, and upper and lower limits for the strength of the agostic interaction were estimated. An NBO analysis of the Ti-CH 2 SiMe 3 bonding found several different contributions, including negative hyperconjugation (populat...

New mononuclear titanium and zirconium imido complexes [M(NR)(R'(2)calix)] [M=Ti, R'=Me, R=tBu (1), R=2,6-C(6)H(3)Me(2) (2), R=2,6-C(6)H(3)iPr(2) (3), R=2,4,6-C(6)H(2)Me(3) (4); M=Ti, R'=Bz, R=tBu (5), R=2,6-C(6)H(3)Me(2) (6), R=2,6-C(6)H(3)iPr(2) (7); M=Zr, R'=Me, R=2,6-C(6)H(3)iPr(2) (8)] supported by 1,3-diorganyl ether p-tert-butylcalix[4]arenes (R'(2)calix) were prepared in good yield from the readily available complexes [MCl(2)(Me(2)calix)], [Ti(NR)Cl(2)(py)(3)], and [Ti(NR)Cl(2)(NHMe(2))(2)]. The crystallographically characterised complex [Ti(NtBu)(Me(2)calix)] (1) reacts readily with CO(2), CS(2), and p-tolyl-isocyanate to give the isolated complexes [Ti[N(tBu)C(O)O](Me(2)calix)] (10), [[Ti(mu-O)(Me(2)calix)](2)] (11), [[Ti(mu-S)(Me(2)calix)](2)] (12), and [Ti[N(tBu)C(O)N(-4-C(6)H(4)Me)](Me(2)calix)] (13). In the case of CO(2) and CS(2), the addition of the heterocumulene to the Ti-N multiple bond is followed by a cycloreversion reaction to give the dinuclear complexes 11 and 12. The X-ray structure of 13.4(C(7)H(8)) clearly establishes the N,N'-coordination mode of the ureate ligand in this compound. Complex 1 undergoes tert-butyl/arylamine exchange reactions to form 2, 3, [Ti(N-4-C(6)H(4)Me)(Me(2)calix)] (14), [Ti(N-4-C(6)H(4)Fc)(Me(2)calix)] (15) [Fc=Fe(eta(5)-C(5)H(5))(eta(5)-C(5)H(4))], and [[Ti(Me(2)calix)](2)[mu-(N-4-C(6)H(4))(2)CH(2)]] (16). Reaction of 1 with H(2)O, H(2)S and HCl afforded the compounds [[Ti(mu-O)(Me(2)calix)](2)] (11), [[Ti(mu-S)(Me(2)calix)](2)] (12), and [TiCl(2)(Me(2)calix)] in excellent yields. Furthermore, treatment of 1 with two equivalents of phenols results in the formation of [Ti(O-4-C(6)H(4)R)(2)(Me(2)calix)] (R=Me 17 or tBu 18), [Ti(O-2,6-C(6)H(3)Me(2))(2)(Me(2)calix)] (19) and [Ti(mbmp)(Me(2)calix)] (20; H(2)mbmp=2,2'-methylene-bis(4-methyl-6-tert-butylphenol) or CH(2)([CH(3)][C(4)H(9)]C(6)H(2)-OH)(2)). The bis(phenolate) compounds 17 and 18 with para-substituted phenolate ligands undergo elimination and/or rearrangement reactions in the nonpolar solvents pentane or hexane. The metal-containing products of the elimination reactions are dinuclear complexes [[Ti(O-4-C(6)H(4)R)(Mecalix)](2)] [R=Me (23) or tBu (24)] where Mecalix=monomethyl ether of p-tert-butylcalix[4]arene. The products of the rearrangement reaction are [Ti(O-4-C(6)H(4)Me)(2) (paco-Me(2)calix)] (25) and [Ti(O-4-C(6)H(4)tBu)(2)(paco-Me(2)calix)] (26), in which the metallated calix[4]arene ligand is coordinated in a form reminiscent of the partial cone (paco) conformation of calix[4]arene. In these compounds, one of the methoxy groups is located inside the cavity of the calix[4]arene ligand. The complexes 24, 25 and 26 have been crystallographically characterised. Complexes with sterically more demanding phenolate ligands, namely 19 and 20 and the analogous zirconium complexes [Zr(O-4-C(6)H(4)Me)(2)(Me(2)calix)] (21) and [Zr(O-2,6-C(6)H(3)Me(2))(2)(Me(2)calix)] (22) do not rearrange. Density functional calculations for the model complexes [M(OC(6)H(5))(2)(Me(2)calix)] with the calixarene possessing either...

A family of ca. 50 imidotitanium precatalysts [Ti(NR)(Me(3)[9]aneN(3))Cl(2)](R = alkyl or aryl; Me(3)[9]aneN(3)= 1,4,7-trimethyltriazacyclononane) were prepared in good yields using semi-automated procedures; high-throughput screening techniques identified seven highly active ethylene polymerisation precatalysts with activities in the range ca. 3 400 to 10 000 kg(PE) mol(-1) h(-1) bar(-1).

Reactions of Ti(NMe(2))(2)Cl(2) with a wide range of primary alkyl and arylamines RNH(2) afforded the corresponding 5-coordinate imido titanium compounds Ti(NR)Cl(2)(NHMe(2))(2) (R = (t)Bu (1), (i)Pr (2), CH(2)Ph (3), Ph (4), 2,6-C(6)H(3)Me(2) (5), 2,6-C(6)H(3)(i)Pr(2) (6), 2,4,6-C(6)H(2)F(3) (7), 2,3,5,6-C(6)HF(4) (8), C(6)F(5) (9), 4-C(6)H(4)Cl (10), 2,3,5,6-C(6)HCl(4) (11), 2-C(6)H(4)CF(3) (12), 2-C(6)H(4)(t)Bu (13)). The compounds 1-13 are monomeric in solution but in the solid state form either N-H...Cl hydrogen bonded dimers or chains or perfluorophenyl pi-stacked chains, depending on the imido R-group. The compound 13 was also prepared in a "one-pot" synthesis from RNH(2) and Ti(NMe(2))(4) and Me(3)SiCl. Reaction of certain Ti(NR)Cl(2)(NHMe(2))(2) compounds with an excess of pyridine afforded the corresponding bis- or tris-pyridine analogues [Ti(NR)Cl(2)(py)(x)](y) (x = 3, y = 1; x = y = 2), and the structure of Ti(2)(NC(6)F(5))(2)Cl(2)(mu-Cl)(2)(py)(4) shows pi-stacking of perfluorophenyl rings. Reaction of Ti(NMe(2))(2)Cl(2) with cross-linked aminomethyl polystyrene gave quantitative conversion to the corresponding solid-supported titanium imido complex. This paper represents the first detailed study of how supramolecular structures of imido compounds may be influenced by simple variation of the imido ligand N-substituent.

Ethylene polymerisation productivities of tris(pyrazolyl)methane-supported catalysts [Ti(NR){HC(Me2pz)3}Cl2] show a dramatically different dependence on the imido R-group compared to those of their TACN analogues, attributed to differences in fac-N3 donor topology; when treated with AliBu3, the zwitterionic tris(pyrazolyl)methide compound [Ti(N-2-C6H4tBu){C(Me2pz)3}Cl(THF)] also acts as a highly active, single site catalyst (TACN = 1,4,7-trimethyltriazacyclononane).

A family of new organometallic and coordination compounds supported by the diamine−bis(phenolate) ligands O2NN‘Me and O2NN‘tBu are reported [H2O2NN‘R = (2-C5H4N)CH2N(CH2-2-HO-3,5-C6H2R2)2, where R = Me (1a) or tBu (1b)]. Reaction of H2O2NN‘R with sodium hydride in THF gives the corresponding sodium salts Na2O2NN‘R (R = Me (2a) or tBu (2b)). Reaction of H2O2NN‘R with Zr(CH2SiMe3)2Cl2(Et2O)2 gives the cis-dichloride derivatives ZrCl2(O2NN‘R) (R = Me (3a) or tBu (3b)), which exist as two isomers (possessing either C 1 (major) or C s symmetry) in dynamic equilibrium with each other in solution. The compound 3b can also be prepared from Na2O2NN‘tBu and ZrCl4(THF)2, but reaction of Na2O2NN‘Me with either ZrCl4 in benzene or ZrCl4(THF)2 in THF gives mixtures of 3a and the eight-coordinate bis(diamine−bis(phenolate)) complex Zr(O2NN‘Me)2 (4a). The latter can also be prepared from 2 equiv of H2O2NN‘Me and Zr(CH2SiMe3)4. Treatment of Zr(NMe2)4 with H2O2NN‘tBu leads to the bis(dimethylamide) derivative Zr(NMe2)2(O2NN‘tBu) (5b). Similar protonolysis reactions between ZrR‘4 (R‘ = CH2SiMe3, CH2CMe3, or CH2Ph) give the corresponding organometallic alkyl or benzyl compounds ZrR‘2(O2NN‘R) [R‘ = CH2SiMe3 (8a, 8b), CH2CMe3 (9a, 9b), or CH2Ph (10a, 10b); R = Me (suffix a) or tBu (suffix b)]. The dichloride complexes ZrCl2(O2NN‘R) (3a, 3b) are also precursors to new organometallic derivatives, and treatment with LiR‘ (R‘ = Me or CH2SiMe3) or R‘MgCl (R‘ = CH2Ph or C3H5) yields ZrR‘2(O2NN‘R) [R‘ = Me (6a, 6b), η3-C3H5 (7b), CH2SiMe3 (8a, 8b), CH2Ph (10a, 10b)]. The thermally unstable bis(η3-allyl) complex 7b is highly fluxional in solution. Reaction of the dibenzyl compound 10a or 10b with B(C6F5)3 in the presence of THF gives the cationic complexes [Zr(CH2Ph)(THF)(O2NN‘R)]+ as the [PhCH2B(C6F5)3]- salts (11a, 11b). The X-ray crystal structures of the compounds 3a, 3b, 4a, 5b, 6a, 6b, and 10a are described.

A comprehensive account of the synthesis, properties, and evaluation of a wide range of ethylene homopolymerization catalysts derived from imido titanium compounds supported by the triazacyclic ligands Me 3 [9]aneN 3 and R 3 [6]aneN 3 is described (Me 3 [9]aneN 3 ) 1,4,7-trimethyltriazacyclononane; R 3 [6]aneN 3 ) 1,3,5-trimethyl-or 1,3,5-tris(n-dodecyl)triazacyclohexane). Conventional preparative-scale reactions afforded the triazacycle-supported imido titanium compounds Ti(NR)(Me 3 [9]aneN 3 )Cl 2 (R ) t Bu (1), 2,6-C 6 H 3 Me 2 , 2,6-C 6 H 3 i Pr 2 , Ph, C 6 F 5 , or CH 2 Ph (6)). Solid phase-supported analogues of 1 and 6 (linked by either the macrocycle or imido ligand to a 1% cross-linked polystyrene support) and representative Me 3 [6]aneN 3 solution phase systems Ti(NR)(R 3 [6]aneN 3 )Cl 2 (R ) Me or n-dodecyl) were also synthesized. At ambient temperature, solution phase Me 3 [9]aneN 3 catalyst systems were more active for ethylene polymerization (methyl aluminoxane (MAO) cocatalyst) than their solid phase-supported or Me 3 [6]aneN 3 analogues. A library of 41 other triazacyclononane-supported catalysts was prepared by the semiautomated, sequential treatment of Ti(NMe 2 ) 2 Cl 2 with RNH 2 and Me 3 [9]aneN 3 . The ethylene polymerization capabilities of 46 compounds of the type Ti(NR)(Me 3 [9]aneN 3 )Cl 2 were evaluated at 100°C (MAO cocatalyst) and compared in representative cases to the corresponding productivities at ambient temperature. Whereas either bulky N-alkyl or N-aryl imido substituents in the compounds Ti(NR)(Me 3 [9]aneN 3 )Cl 2 were sufficient to give highly active catalysts at ambient temperature, only those with bulky N-alkyl groups excelled at 100°C. Polymer end group analysis indicated that polymeryl chain transfer to both AlMe 3 and ethylene monomer is an active mechanism in these systems. The use of MAO pretreated with BHT-H (BHT-H ) 2,6-di-tert-butyl-4-methylphenol) led to higher productivites, increased polymer molecular weights, and more polymer chain unsaturations, but productivity decreased when a large excess of BHT-H was used.