Reactions between Mo(N-t-Bu)₂(CH₂-t-Bu)₂ or Mo(NAdamantyl)₂(CH₂CMe₂Ph)₂ and 3 equiv of HCl in the presence of 1 equiv of PPh₂Me yield Mo(NR)(CHR')(PPh₂Me)Cl₂ complexes, from which Mo(NR)(CHR')(PPh₂Me)(OAr)Cl complexes (OAr = a 2,6-terphenoxide) can be prepared. The Mo(NR)(CHR')(PPh₂Me)(OAr)Cl complexes were evaluated as cross-metathesis catalysts between cyclooctene and Z-1,2-dichloroethylene. The efficiencies of the test reaction for complexes in which OAr = OTPP, OHMT, OHIPT, or OHTBT (where OTPP is 2,3,5,6-tetraphenylphenoxide, OHMT is hexamethylterphenoxide, OHIPT is hexaisopropylterphenoxide, and OHTBT is hexa-t-butylterphenoxide) maximize when OAr is OHMT or OHIPT. Mo(N-t-Bu)(CH-t-Bu)(PPh₂Me)Cl₂ is essentially inactive for the reaction between cyclooctene and Z-1,2-dichloroethylene. X-ray structural studies were carried out on Mo(NAd)(CHCMe₂Ph)(PPh₂Me)Cl₂, Mo(N-t-Bu)(CH-t-Bu)(PPh₂Me)(OHMT)Cl, Mo(NAd)(CHCMe₂Ph)(Cl)(OHTBT)(PMe₃), and [Mo(NAd)(CHCMe₂Ph)(PMe₃)(Cl)]₂(μ-O), the product of the reaction between Mo(NAd)(CHCMe₂Ph)(Cl)(OHTBT)(PMe₃) and 0.5 equiv of water.

Reactions between Z-XCH=CHX where X = Cl, CF₃, or CN and Mo(N-t-Bu)(CH-t-Bu)(OHIPT)Cl(PPh₂Me) (OHIPT = O-2,6-(2,4,6-i-Pr₃C₆H₂)₂C₆H₃) produce Mo(N-t-Bu)(CHX)(OHIPT)Cl(PPh₂Me) complexes. Addition of 2,2'-bipyridyl (Bipy) yields Mo(N-t-Bu)(CHX)(OHIPT)Cl(Bipy) complexes, which could be isolated and structurally characterized. The reaction between Mo(N-t-Bu)(CH-t-Bu)(OHMT)Cl(PPh₂Me) (OHMT = O-2,6-(2,4,6-Me₃C₆H₂)₂C₆H₃) and Z-ClCH=CHCl in the presence of Bipy produces a mixture that contains both Mo(N-t-Bu)(CHCl)(OHMT)Cl(PPh₂Me) and Mo(N-t-Bu)(CHCl)(OHMT)Cl(Bipy), but the relatively insoluble product that crystallizes from toluene-d ₈ is the phosphoniomethylidene complex, [Mo(N-t-Bu)(CHPPh₂Me)(OHMT)(Cl)(Bipy)]Cl. The Mo(N-t-Bu)(CHX)(OHIPT)Cl(PPh₂Me) complexes (X = Cl or CF₃) were confirmed to initiate the stereoselective cross-metathesis between Z-5-decene and Z-XCH=CHX.

3,3′,5,5′-Tetra-tert-butyl-2′-sulfanyl[1,1′-biphenyl]-2-ol (H2[tBu4OS]) was prepared in 24 % yield overall from the analogous biphenol using standard techniques. Addition of H2[tBu4OS] to Mo(NAr)(CHCMe2Ph)(2,5-dimethylpyrrolide)2 led to formation of Mo(NAr)(CHCMe2Ph)[tBu4OS], which was trapped with PMe3 to give Mo(NAr)(CHCMe2Ph)[tBu4OS](PMe3) (1(PMe3)). An X-ray crystallographic study of 1(PMe3) revealed that two structurally distinct square pyramidal molecules are present in which the alkylidene ligand occupies the apical position in each. Both 1(PMe3)A and 1(PMe3)B are disordered. Mo(NAd)(CHCMe2Ph)(tBu4OS)(PMe3) (2(PMe3); Ad=1-adamantyl) and W(NAr)(CHCMe2Ph)(tBu4OS)(PMe3) (3(PMe3)) were prepared using analogous approaches. 1(PMe3) reacts with ethylene (1 atm) in benzene within 45 minutes to give an ethylene complex Mo(NAr)(tBu4OS)(C2H4) (4) that is isolable and relatively stable toward loss of ethylene below 60 °C. An X-ray study shows that the bond distances and angles for the ethylene ligand in 4 are like those found for bisalkoxide ethylene complexes of the same general type. Complex 1(PMe3) in the presence of one equivalent of B(C6F5)3 catalyzes the homocoupling of 1-decene, allyltrimethylsilane, and allylboronic acid pinacol ester at ambient temperature. 1(PMe3), 2(PMe3), and 3(PMe3) all catalyze the ROMP of rac-endo,exo-5,6-dicarbomethoxynorbornene (rac-DCMNBE) in the presence of B(C6F5)3, but the polyDCMNBE that is formed has a random structure.