An X-ray structural study of Mo(NAd)(CHCMe2Ph)(2,5-Me2NC4H2)2 (1; Ad = 1-adamantyl) reveals it to contain one η1-2,5-Me2NC4H2 ring and one η5-2,5-Me2NC4H2 ring. The structures of Mo(NAr)(CHCMe2Ph)(pyrrolide)2 (Ar = 2,6-i-Pr2C6H3) complexes that contain 2,3,4,5-tetramethylpyrrolides, 2,5-diisopropylpyrrolides, or 2,5-diphenylpyrrolides are analogous to that of 1. In contrast, Mo(NAr)(CH2CMe2Ph)(indolide)2 (6) was shown to contain two η1-bound indolides. Monohexafluoro-t-butoxide pyrrolide (MAP) species can be prepared, either through addition of one equiv of Me(CF3)2COH to a bispyrrolide or through reactions between the lithium pyrrolide and the bishexafluoro-t-butoxide. A trimethylphosphine adduct of a bispyrrolide, Mo(NAd)(CHCMe2Ph)(η1-NC4H4)2(PMe3), has been prepared and structurally characterized, while a PMe3 adduct of MAP hexafluoro-t-butoxide species was found to have PMe3 bound approximately trans to the pyrrolide. This adduct serves as a model for the structure of the initial olefin adduct in olefin metathesis.

Three substituted tris(pyrrolyl-alpha-methyl)amines (H(3)[Aryl(3)TPA]) (Aryl = 2,4,6-C(6)H(2)Me(3), 2,4,6-C(6)H(2)(i-Pr)(3) (Trip), or 3,5-C(6)H(3)(CF(3))(2)) have been prepared. An X-ray study of [Trip(3)TPA]MoCl shows it to be a distorted trigonal bipyramidal species in which the 2,4,6-triisopropylphenyl substituents surround and protect the apical chloride. Attempts to prepare other Mo, Zr, and Hf complexes yielded species in which one pyrrole-containing arm remained free (Mo) or dimethylamine remained in the coordination sphere of [Aryl(3)TPA](3-) complexes (Zr, Hf).

Reaction of Li(3,5-R(2)-pyrazolide) (R = tBu or Ph, dXpz) with Mo(NAr)(CHCMe(2)Ph)(OTf)(2)(DME) yields Mo(NAr)(CHCMe(2)Ph)(dXpz)(2) in good yield. These complexes react with alcohols or the surface silanols of silica, to yield bis-alkoxy and surface mono-siloxy alkene metathesis catalysts, respectively.

Monosiloxide and disiloxide complexes have been prepared through the addition of silanols to Mo(NR)(CHCMe 2 Ph)(pyrrolyl) 2 species [R ) 1-adamantyl (Ad) or 2,6-i-Pr 2 C 6 H 3 (Ar)]. The silanols employed include (t-Bu) 3 SiOH (HSilox), (i-Pr) 3 SiOH, (Me 3 Si) 3 SiOH, (t-Bu-O) 3 SiOH, Me 2 (t-Bu)SiOH, and Ph 3 SiOH. The monoSilox complex, Mo(NAr)(CHCMe 2 Ph)(Silox)(pyrrolyl) (2a), could be isolated, while Mo(NAd)(CHCMe 2 Ph)(Silox)(pyrrolyl) was observed in situ but could not be crystallized. Disiloxides that could be crystallized include Mo(NAd 5), and Mo(NAr)(CHCMe 2 Ph)[OSiMe 2 (t-Bu)] 2 (6); other disiloxide examples could be observed in situ but could not be crystallized. Compound 2a reacts readily with (CF 3 )Me 2 COH, (CF 3 ) 2 MeCOH, (CF 3 ) 2 CHOH, ArOH, C 6 F 5 OH, (-)-menthol, and (-)borneol to give compounds of the type Mo(NAr)(CHCMe 2 Ph)(Silox)(OR) (3a-g) in situ. No reaction was observed upon heating of 1b under 5 atm of ethylene at 120 °C in toluene-d 8 ; only at 240 °C in o-dichlorobenzene-d 4 did 1b react with ethylene to yield CH 2 dCHCMe 2 Ph, but the Mo-containing product could not be identified. Compound 2a reacts with ethylene at 120 °C to give Mo(NAr)(CH 2 )(Silox)(pyr), while 3a-e react with ethylene at ∼60 °C; methylene species could be observed in several cases but could not be isolated. X-ray studies were carried out for 1b and 2a.

The N,N-dimethylanilino tungsten alkylidyne complex [W(⋮CC6H4NMe2-4)(O2CCF3)(CO)2(NC5H4Me-4)2] has been synthesized, characterized, and employed as a precursor to neutral and cationic 2,2‘-dipyridyl and TMEDA (N,N,N‘,N‘-tetramethylethylenediamine) complexes, which display dual blue and yellow fluorescences in CH2Cl2 solutions at ambient temperatures with surprisingly high quantum yields for this class of organometallic complex. The efficiencies of the radiative emissions from the 2,2‘-dipyridyl complex [W(⋮CC6H4NMe2-4)(O2CCF3)(CO)2{κ2-2,2‘-(NC5H4)2}] are particularly impressive. The dual nature of the emissions (λem ≈ 450 and 540−580 nm) is attributed to independent, short-lived (ns) “twisted intramolecular charge transfer” (1TICT) and 1dW−π*W ⋮ CAr states, respectively, the former being well understood in organic aromatic systems, but yet to be described for organometallic complexes.