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Addition of four equivalents of lithium 2,5-dimethylpyrrolide to a solution of [Mo(NAr)(OR(F6))(2)(CHC(5)H(4))](2)Fe (OR(F6)=OCMe(CF(3))(2)) in dichloromethane led to [Mo(NAr)(Me(2)Pyr)(2)(CHC(5)H(4))](2)Fe (2; Me(2)Pyr=2,5-dimethylpyrrolide) and lithium hexafluoro-tert-butoxide, which crystallizes out upon cooling the reaction mixture to -35 degrees C. Attempts to prepare parent pyrrolide complexes analogous to 2 resulted in the formation of a mixture of two products. The one that could be isolated contains one equivalent of lithium pyrrolide per molybdenum, that is [Mo(NAr)(Pyr)(3)(CHC(5)H(4))](2)FeLi(2) (3). The X-ray structure obtained shows it to be a dimer of dimers in which each lithium atom is bound to three pyrrolides. Addition of four equivalents of lithium 2,5-dimethylpyrrolide to [Mo(NAr)(OR(F6))(2)](2)(DME)(2)(CH-1,4-C(6)H(4)CH) (1 b) in cold DME produced [Mo(NAr)(Me(2)Pyr)(2)](2)(CH-1,4-C(6)H(4)CH) (4) in good yield, in which the bridging alkylidene is derived from 1,4-divinylbenzene. Three equivalents of (S)-H(2)[Biphen] are required for a clean reaction with 3 to form [Mo(NAr)(Biphen)(CHC(5)H(4))](2)Fe (5) (H(2)[Biphen]=3,3'-di-tert-butyl-5,5',6,6'-tetramethyl-1,1'-biphenyl-2,2'-diol), Li(2)[Biphen], and two equivalents of pyrrole. Reactions involving 4 with the chiral diols are the best behaved. Brown [Mo(NAr)(Benz(2)Bitet)](2)(CH-1,4-C(6)H(4)CH) (6) can be isolated upon addition of (R)-H(2)[Benz(2)Bitet] (H(2)[Benz(2)Bitet]=(3,3'-dibenzhydryl-5,5',6,6',7,7',8,8'-octahydro-1,1'-binaphthyl-2,2'-diol) to 4, while addition of (R)-H(2)[Mes(2)Bitet] (H(2)[Mes(2)Bitet]=3,3'-dimesityl-5,5',6,6',7,7',8,8'-octahydro-1,1'-binaphthyl-2,2'-diol) to 4 yields [Mo(NAr)(Mes(2)Bitet)](2)(CH-1,4-C(6)H(4)CH) (7). Compounds 5, 6, and 7 were employed as initiators for the polymerization of 2,3-dicarbomethoxynorbornadiene (DCMNBD) and 2,3-bis(trifluoromethyl)norbornadiene (NBDF6).

A series of monomers suitable for ring-opening metathesis polymerization (ROMP) containing a side chain liquid crystal mesogen have been synthesized, where the mesogen is biphenyl-4-carboxylic acid 4-(1-butoxycarbonyl-ethoxy)phenyl ester (abbreviated as BPP4). Two of the monomers have BPP4 attached to norbornene with a 6- or 10-carbon spacer ((R)-4‘-(5-bicyclo[2.2.1]hept-5-en-2-yl-pentyloxy)-BPP4, NB6wBPP4, and (R)-4‘-(10-bicyclo[2.2.1]hept-5-en-2-yl-decyloxy)-BPP4, NB10wBPP4, respectively), and the third monomer has BPP4 attached to norbornadiene via a 10-carbon spacer ((R)-4‘-(10-bicyclo[2.2.1]hepta-2,5-dien-2-yl-decyloxy)-BPP4, NBD10wBPP4). The monomers were polymerized by ROMP using the bimetallic initiator, {Mo(NAr)(ORF6)2[=CHC5H4]}2Fe (Ar = 2,6-diisopropylphenyl, ORF6 = OCMe(CF3)2). ABA triblock copolymers were also synthesized where the B = NBD10wBPP4 or NBnwBPP4 (n = 6, 10) and A = methyltetracyclododecene (MTD). All polymerizations are living with isolated yields greater than 90% and polydispersi...

An X-ray study of [(THF)(RF6O)2(ArN)MoCH]2(1,4-C6H4) (ORF6 = OCMe(CF3)2; Ar = 2,6-diisopropylphenyl; THF = tetrahydrofuran; 1b), which is closely related to known [(DME)(RF6O)2(ArN)MoCH]2(1,4-C6H4) (DME = 1,2-dimethoxyethane; 1a), showed it to be the expected bimetallic species in which each end is approximately a trigonal bipyramidal monoadduct of a syn alkylidene with the THF coordinated to the NOO face of the metal trans to the MoC bond. Treatment of 1a with lithium tert-butoxide yielded [(t-BuO)2(ArN)MoCH]2(1,4-C6H4) (2). Addition of divinylferrocene to Mo(CHCMe2Ph)(NAr)(ORF6)2 produced the bimetallic species {(RF6O)2(ArN)Mo[CH(C5H4)]}2Fe (3), which upon treatment with lithium tert-butoxide produced a related tert-butoxide complex (4). X-ray studies of 3 and 4 showed them to be “syn/syn” bimetallic species related to 1b. In solution two resonances can be observed in proton NMR spectra in the alkylidene region for the “syn/anti” isomer of 1a, 2, 3, and 4; the total amount varies between 4 and 20% of th...

A series of new diamidoether ligands of the form {[RN(SiMe2)]2O}2- (R = 2,4,6-Me3Ph, 2,6-iPr2Ph, 3,5-(CF3)2Ph), termed [RNON]2-, were prepared via dilithiation of the precursors H2[RNON], which were synthesized from the reaction of O(SiMe2Cl)2 with the appropriate lithium amide. Reaction of the previously reported Li2[tBuNON] with FeX3 (X=C1, Br) yields dinuclear halide-bridged iron(III) complexes that show an unusual quantum spin-admixed magnetic state. Complexes of iron(III) with the aryl-NON ligands, however, form rare lithium “ate” structures. {[RNON]Co}2 complexes (R=tBu, 2,4,6-Me3Ph) are dinuclear with amido bridges and Co-Co bonds. Each Co(II) centre is roughly trigonal monopyramidal. The analogous reactions with UO2C12(THF)3 give dark red powders. For R=tBu, {UO2[tBuNON]}2 complexes are formed that may have structures similar to {[RNON]Co}2.

An unusual metal-ligand binding motif is found in dimeric cobalt(II) complexes coordinated by diamidoether ligands that bridge the metals in a 'serpentine' fashion through the ether donors of the ligand backbone rather than the amido groups.