Tong Ren

Ru-σ-alkynyl compounds of tetraanilinopyridinato-diruthenium(II,III) core: synthesis and structural characterization

Abstract Synthesis and characterizations are reported for three diruthenium(II,III) compounds of general formula Ru 2 (ap) 4 (Cue606CR), where ap=2-anilinopyridinate and R=Si(CH 3 ) 3 ( 3 ), H ( 4 ), and CH 2 OCH 3 ( 5 ). Molecular structure determination reveals that the Ru–Ru bond lengths are 2.3162(5) and 2.3234(7) A for 3 and 5 , respectively, while the Cue606C bond is not significantly elongated compared with the free alkyne. Compounds 3 – 5 undergo reversible one-electron oxidation and reduction at potentials around 200 and −1030 mV, respectively. At more positive potential, compounds 3 and 4 undergo the second one-electron oxidation quasireversibly or irreversibly without decomposition, while compound 5 is oxidatively degraded.

Homo-dinuclear σ-alkynyl complexes: past, present and opportunities

Abstract Homo-dinuclear alkynyl complexes with a distinct metal–metal bond constitute a rapidly growing field, where the focus is placed on compounds based on ruthenium, molybdenum, tungsten or rhodium. Interesting characteristics of these complexes include paramagnetism, intense charge-transfer absorptions, tunable bridging ligands, which may not be easily accessible in mononuclear acetylide systems. These complexes have significant potential for use in both molecular electronics and supramolecular chemistry. In this short account, previous work in this area is assessed, and each of the major groups of complexes is discussed in terms of both the synthetic strategies and structural motifs.

Expanding cavitand chemistry: the preparation and characterization of [n]cavitands with n>=4.

The preparation of cavitands composed of 4, 5, 6, and 7 aromatic subunits ([n]cavitands, n=4-7) is described. The simple, two-step synthetic procedure utilized readily available starting materials (2-methylresorcinol and diethoxymethane). The two cavitand products having 4 and 5 aromatic subunits exhibited highly symmetric cone conformations, while the larger cavitands (n = 6 and 7) adopt conformations of lower symmetry. 1H NMR spectroscopic studies of [6]cavitand and [7]cavitand revealed that these hosts undergo exchange between equivalent conformations at room temperature. The departure of these two cavitands from cone conformations is related to steric crowding on their Ar-O-CH2-OAr bridges and is predicted by simple molecular mechanics calculations (MM2 force field). X-ray diffraction studies on single crystals of the [4]cavitand, [5]cavitand, and [6]cavitand hosts afforded additional experimental support for these conclusions.

Ru2(DMBA)4(BF4)2 and Ru2(DMBA)4(NO3)2: the first examples of diruthenium compounds containing BF4− and NO3− as ligands

Abstract Diruthenium compounds Ru2(DMBA)4X2 (DMBA=N,N′-dimethylbenzamidinate, X=BF4 (1) and NO3 (2)) were obtained by treating Ru2(DMBA)4Cl2 with AgX. The single crystal X-ray diffraction study revealed that the anions have been incorporated into the coordination sphere of the Ru center as the axial ligand and the Ruue5f8Y bond lengths are 2.378(3) (Ruue5f8F) and 2.322(2) A (Ruue5f8O) for 1 and 2, respectively. The Ruue5f8Ru bond lengths, 2.2646(6) and 2.2865(4) A for 1 and 2, respectively, are slightly shorter than that of the parent molecule (2.3224(7) A).

Synthesis, characterization and electrochemistry of diruthenium complexes linked by aryl acetylide bridges

The reactions between Ru2(ap)4Cl and the appropriate lithiated aryl acetylene resulted in the complexes Ru2(ap)4(Cue606Cue5f84-C6H4Cue606CX) with X as SiMe3 (1), H (2) and Ru2(ap)4 (3), 1,3-[Ru2(ap)4(Cue606C)]2(C6H4) (4), 1,3-[{Ru2(ap)4(Cue606C)}2]C6H3ue5f85-Cue606CH (5) and 1-[Ru2(ap)4(Cue606C)]C6H3ue5f83,5-(Cue606CH)2 (6), where ap is 2-anilinopyridinate. The spectroscopic and electrochemical properties of the new complexes have been assessed. Complexes 3, 4 and 6 display two-electron oxidation and reductions, implying the absence of any significant electronic interaction between the two Ru2(ap)4 units in these complexes.

O-Demethylation reaction at a diruthenium core: synthesis and structural study of two novel diruthenium compounds

Abstract The reaction between Ru2(OAc)4Cl and di(o-methoxyphenyl)formamidine led to the unexpected products trans-Ru2(O2CCH3)2(μ-N,N′-η2-N,O-o-MeOForm)(μ-N,N′-η2-N,O-o-MeOForm′) (1) and Ru2(O2CCH3)(μ-N,N′-o-MeOForm)(μ-N,N′-η2-N,O-o-MeOForm)(μ-N,N′-η2-N,O-o-MeOForm′) (2), where o-MeOForm is di(o-methoxyphenyl)formamidinate, and o-MeOForm′ is the O-demethylation derivative of o-MeOForm, (o-methoxyphenyl)(o-oxyphenyl)formamidinate. Both compounds 1 and 2 were structurally characterized by X-ray diffraction analysis, and are isoelectronic with the previously studied chloro-tetracarboxylatodiruthenium(II,III) and chlorotetrakis(diarylformamidinato)diruthenium(II,III) on the basis of structural and magnetic data.

Synthesis and crystallographic characterization of dinuclear silver complexes supported by N,N′-diarylformamidinates

Synthesis of two new disilver(I) complexes of diarylformamidinate bearing o-ethoxy (1) and m-butoxy substituents (2) is described. Crystallographic characterization revealed that each Ag center is supported primarily by two N centers in approximate co-linear geometry. Secondary coordination of ethereal O center to Ag was also observed in molecule 1. Conformational isomerism exists in the crystal of 2, and is attributed to the low energy-barrier free rotation of aryls. Crystal data: compound 1 crystallizes in orthorhombic space group Pbca, a=11.392(1), b=15.007(1), c=19.363(2) A, Z=4; compound 2 crystallizes in tetragonal space group P42/n, a=24.152(2), c=14.371(2) A, Z=8.

Synthesis and characterization of trans-phenylethynylalkynyl adducts on a tetraanilinopyridinato-diruthenium(III) core

Treating Ru 2 ( ap ) 4 Cl with large excess of LiC 2 Ph led to the isolation of previously unidentified trans -Ru 2 ( ap ) 4 (C 2 Ph) 2 ( 2a ) where ap is 2-anilinopyridinate. Reactions between Ru 2 ( ap ) 4 (C 2 X) and LiC 2 Ph in excess yielded similar bis-alkynyl compounds trans -(PhC 2 )[Ru 2 ( ap ) 4 ](C 2 X) (X=SiMe 3 , 2b , C 2 SiMe 3 , 2c ). Also reported are electrochemical and spectroscopic characterizations of compounds 2a – c and X-ray structural analysis of compounds 2a and 2b .

Crystallographic characterization of N,N'-diarylformamidines bearing an alkoxy substituent at either the meta- or ortho-position

AbstractCrystal structures of four diphenylformamidines bearing phenyl substituents ortho-CH3O (1), ortho-C2H5O (2), meta-CH3O (3), and meta-nBuO (4) are reported. In each of the structures, formamidine exists as an unsymmetrical cyclic hydrogen bond dimer, and the geometry of the amidine unit is consistent with the localized C–N and C=N bonds. Interesting conformations due to the orientation of aryl groups were also observed. Crystal Data: 1, orthorhombic, Pbca, a = 11.297(1) Å, b = 15.092(1) Å, c = 16.380(2) Å, V = 2792.6(4) Å3, Z = 8; 2, triclinic, Pn