The synthesis, structural, and electronic properties of nine 1,3-diphenyl-6-alkyl/aryl substituted pentafulvenes were studied. Pyrene ring π-π interactions were revealed from analysis of the experimental crystal packing of 1,3-diphenyl-6-(1-pyrene)fulvene and supporting DFT calculations. Photophysical properties derived from UV-vis and fluorescence emission measurements demonstrated tunable and low HOMO-LUMO band gaps for the series. The presented results point to a model synthetic approach for incorporation of extended π systems and donor-π-acceptor groups for fulvene-based electronic materials.

This report details the synthesis of new NCN trianionic pincer ligand precursors and metalation reactions to form group (IV) complexes. N,N'-[1,3-phenylenebis(methylene)]bis-2,6-diisopropylaniline [2,6-(i)PrNCN]H(3) (8) was converted to the N,N'-substituted Si(IV), Sn(IV), Mg(II), and Zn(II) derivatives. [2,6-(i)PrNCHN](SiMe(3))(2) (9-Si) and [2,6-(i)PrNCHN](SnMe(3))(2) (9-Sn) form by first treating 8 with MeLi followed by Me(3)MCl, where M = Si or Sn. Single crystal X-ray experiments indicate 8, 9-Si, and 9-Sn have similar structural features in the solid state. [2,6-(i)PrNCHN](mu-MgCl.THF)(2) (12) forms by treating 8 with MeMgCl, and its solid state structure revealed a bis-mu-MgCl bridging unit. The (1)H NMR spectrum of 12 reveals a dynamic process occurs in solution. A variable temperature (1)H NMR experiment failed to quench the dynamic process. {[2,6-(i)PrNCHN]Zn}(2) (13) forms upon treating {[2,6-(i)PrNCHN]Li(2)}(2) (10) with anhydrous ZnCl(2) and is a dimer in the solid state. Again, dynamic (1)H NMR behavior is observed, and a mechanism is provided to explain the apparent low symmetry of 13 in solution. Extension of the aliphatic arm of the NCN ligand provides the new N(C)C(C)N pincer ligand precursors N,N'-(2,2'-(1,3-phenylene)bis(ethane-2,1-diyl))bis(3,5-bis(trifluoromethyl)aniline) [3,5-CF(3)N(C)C(C)N]H(3) (16) and [3,5-CF(3)N(C)CH(C)N](SiMe(3))(2) (17). A more rigid ligand architecture was accessed by synthesis of the anthracene derived pincer ligand anthracene-1,8-diylbis(N-3,5-bistrifluormethylaniline) [3,5-CF(3)N(C)C(anth)(C)N]H(3) (18). Treating {Zr(NMe(2))(4)}(2) with 2 equiv of 16 provides the dimer {(mu-3,5-CF(3)N(C)CH(C)N)Zr(NMe(2))(3)NHMe(2)}(2) (19). Treating Hf(NMe(2))(4) with 18 provides the bimetallic complex (mu-3,5-CF(3)N(C)CH(anth)(C)N){Hf(NMe(2))(3)NHMe(2)}(2) (20) in which one ligand bridges two Hf(IV) ions. Salt metathesis between 10 and ZrCl(2)(NMe(2))(2)(THF)(2) provides the mononuclear complex [2,6-(i)PrNCHN]Zr(NMe(2))(2) (21) in which the NCN ligand is bound as a chelating diamide. Thermoysis of 21 does not lead to formation of a trianionic pincer complex. Instead, treating HfCl(4) with {[2,6-(i)PrNCN]Li(3)}(2) (11) followed by MeLi provides the trianionic pincerate complex [2,6-(i)PrNCNHfMe(2)][Li(DME)(2)] (23). In the solid state the Hf ion has distorted trigonal bipyramidal geometry.

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The synthesis and characterization of trianionic [ t BuOCO]3− pincer-supported tungsten alkylidene and alkylidyne complexes are described. The reaction of an equimolar ratio of ( t BuO)3WCC(CH3)3 (where t BuO = tert-butoxide) with [ t BuOCO]H3 (9) and 2,6-diisopropylphenol affords the alkylidene [ t BuOCO]WCHC(CH3)3(O-2,6-C6H3- i Pr2) (10), with a five-coordinate tungsten center that adopts a distorted square-pyramidal geometry. Treatment of (Np)3WCC(CH3)3 (11) with 9 provides an equilibrium mixture of the two isomeric alkylidenes with the general formula [( t BuOCO)WCHC(CH3)3(μ- t BuOCHO)WCHC(CH3)3( t BuOCO)] (12 kin and 12 therm ). Single crystals of the two isomers cocrystallize and were amenable to X-ray diffraction studies, which revealed subtle differences in their molecular structures, most notably the orientation of the bridging ligand. The complexes are each comprised of two square-pyramidal tungsten ions linked by the diphenolate form of the OCO ligand. Isomer 12 kin could not be isolated independently; however, adding PMe2Ph to the metalation between 11 and 9 provided 12 therm exclusively, thus enabling a full set of characterization techniques including 2-D NMR spectroscopy. Salt metathesis between [ t BuOCHO]K2(THF)2 (15) and (DME)Cl3WCC(CH3)3 (16) in diethyl ether produces the alkylidyne ( t BuOCHO)WCC(CH3)3Cl (17) as the major product along with 12 kin and other unidentified decomposition products. As a consequence, characterization of 17 was limited to 1H NMR spectroscopy and mass spectrometry.

A series of co-crystallization experiments were performed using 1,4-dibromo- and 1,4-diiodotetrafluorobenzene (Br2F4bz and I2F4bz), as well as 4,4’-dibromo- and 4,4’-diiodooctafluorobiphenyl (Br2F8bph and I2F8bph), with nine N-heterocyclic diamines and the bicyclic,...