John F. Gallagher

Novel derivatives of ansa-titanocenes procured from 6-phenylfulvene: a combined experimental and theoretical study

Abstract The previously prepared trans-[(1,2-diphenyl-1,2-dicyclopentadienyl)ethanediyl] titanium(IV) dichloride, [1,2-(Ph)2C2H2{η5-C5H4}2]Ti(Cl)2, was synthesised using an alternative procedure, from which its crystal structure was determined. Using this compound, a variety of other ansa-titanocene derivatives were synthesised by replacement of the chloride ligands with selected substituents. Thus RTi(X)(Y) systems where R=1,2-(Ph)2C2H2η5-C5H42; X=Y=CH3; X=CH3, Y=Cl; X=Y=NCS; X=Y=NCO; X=Y=OPh and (X/Y)=O have been synthesised and characterised. DFT calculations were performed on the complexes trans-[(1,2-diphenyl-1,2-dicyclopentadienyl)-ethanediyl] titanium(IV) dichloride, bis-(6,6-diphenylfulvene)titanium and bis-(6,6-diphenylfulvene)iron. This demonstrated the role that the metal centre plays in their formation, generating either an ansa-metallocene, a ‘tucked in’ fulvene complex or a metallocene coordinating fulvene anions.

A substituted BF2-chelated tetraarylazadipyrromethene as an intrinsic dual chemosensor in the 650–850 nm spectral range

The synthesis and spectral analysis of a new class of long wavelength intrinsic fluorosensor is reported. Chemosensor performance reveals large off/on fluorescence intensity responses to acid analyte with low response to microenvironment polarity. Application to ratiometric fluorescence/UV-visible analysis is outlined.

Electrochemical anion recognition by redox-responsive unnatural amino acid derivatives; the X-ray crystal structure of N-ferrocenoyl glycine methyl ester, (η5-C5H5)Fe(η5-C5H4)CONHCH2COOMe

Abstract N-Ferrocenoyl glycine ester derivatives FcCONHCH2COOR (Fc=(η5-C5H5)Fe(η5-C5H4); R=methyl (1), ethyl (2) and benzyl (3)) have been prepared by coupling ferrocene carboxylic acid to a series of glycine esters using 1,3-dicyclohexylcarbodiimide (DCC), 1-hydroxybenzotriazole (HOBT) and Et3N in CH2Cl2. The electrochemical anion sensing using a platinum microdisk working electrode of these N-ferrocenoyl glycine ester derivatives is reported. The crystal structure of 1 has been determined; principal dimensions are amide N(H)CO 1.229(3) A, ester CO 1.183(3) A with N–H⋯OC(amide) as the primary intermolecular hydrogen bond, N⋯O 2.804(3) A.

Transition-metal Schiff-base complexes as ligands in tin chemistry. Part 3. An X-ray crystallographic and tin-119 Mössbauer spectroscopic study of adduct formation between tin(IV) Lewis acids and nickel 3-methoxysalicylaldimine complexes

1:1 Addition complexes of [NiIIL]·H2O [H2L =N,N′-bis(3-methoxysalicylidene)ethylenediamine (3MeO-H2salen), N,N′-bis(3-methoxysalicylidene)propane-1,2-diamine (3MeO-H2salpn) or N,N′-bis(3-methoxysalicylidene)-o-phenylenediamine (3O-H2salphen)] with SnR2Cl2(R = Me or Ph), SnBunCl3, or SnCl4 have been found to be generally monoaqua adducts of the tin Lewis acids with the water engaged in hydrogen bonding with the methoxy and phenolic oxygen atoms of the Schiffbase ligand. Both water and methoxy oxygen atoms are involved in donor-bond formation to tin in the polymeric structures 2SnMe2Cl2·[Ni(3MeO-salen)]·H2O and SnMe2Cl2·[Ni(3MeO-salphen)]·H2O, each of which has two very different tin environments. The two octahedral tin sites in the structure of SnMe2Cl2·2[Ni(3MeO-salphen)·H2O] appear to result from two isomeric forms of the adduct co-existing in a lattice as a result of hydrogen-bonding interactions. Crystal-structure determinations revealed that the monoaqua adducts of dimethyltin dichloride which exist in the structures SnMe2Cl2·[Ni(3MeO-salen)]·H2O and SnMe2Cl2·[Ni(3MeO-salon)]·H2O differ in that, in the former tin is in a trigonal-bipyramidal environment, whereas in the latter it is in an octahedral environment as a result of an intermolecular Sn ⋯ Cl contact of 3.615 A.

The linear and nonlinear optical properties of organometallic chromophores derived from ferrocene, [Fe2(η5-C5H5)2(CO)2(μ-CO)(μ-CCH3)]+[BF4]− and terthienyl spacers. Crystal structure of 2-[(E)-2-ferrocenylethenyl]-5-(2-thienyl)thiophene

Several chromophores based on ferrocene, [Fe2( 5 -C5H5)2(CO)2(-CO)(-CCH3)] + and terthiophene or dithienylbenzo[c]thiophene have been synthesized. Both thienyls have been shown to act as good donor end groups in their own right but contrary to our expectations the benzo[c]thiophene merocyanine has a lower hyperpolarizablity (344 × 10 − 30 esu) than its thienyl congener (650 ×10 −30 esu). The structure of 2-[(E)-2-ferrocenylethenyl]-5-(2-thienyl)thiophene has been determined by single crystal X-ray diffraction. The terminal thienyl (thp) group is disordered over two orientations about the bithienyl C(sp 2 )C(sp 2 ) bond such that the two sulfur atoms in either thp ring are positioned trans/cis in the ratio 0.628(4):0.372(4). The integrity of the alkenyl CC remains with a bond length of 1.332(2) A and the CC lengths adjacent are 1.453(4)/1.441(4) A . Twisting of the rings from planarity occurs along the Fc–CC–(thp)–(thp) axis: the angle which the ethenylthiophene CCC4H2S moiety makes with the C5H4 is 11.2(2)°, and with the major orientation of the disordered terminal thienyl group, 16(1)°.

The effect of different bithienyl spacers on the linear and non-linear optical properties of organometallic chromophores derived from [Fe2(η5-C5H5)2(CO)2(μ-CO)(μ-C–CH3)]+ [BF4]−: Crystal structure of [Fe2(η5-C5H5)2(CO)2(μ-CO)(μ-(E)-C–CHCH-7-(thieno[3,2-e][1]benzothiophene))]+ [BF4]−

Abstract Two series of organometallic merocyanines incorporating a variety of bithienyl moieties both as spacers and end groups were synthesised. In the first series the bithienyls function as end groups and were appended to an acceptor derived from [Fe 2 (η 5 -C 5 H 5 ) 2 (CO) 2 (μ-CO)(μ-C–CH 3 )] + [BF 4 ] − . In the second series, ferrocene acting as an organometallic donor was incorporated into the chromophores at the far terminus of the bithienyl spacers. The molecular first hyperpolarisabilities β of the second series were determined by hyper-Rayleigh scattering and the values range from 429×10 −30 esu to 867×10 −30 esu in dichloromethane. A single crystal X-ray study of [Fe 2 (η 5 -C 5 H 5 ) 2 (CO) 2 (μ-CO)(μ-( E )-C–CHCH-7-(thieno[3,2- e ][1]benzothiophene))] + [BF 4 ] − ·CH 2 Cl 2 is reported.

Synthesis, structural and conformational analysis of a 3 × 3 isomer grid based on nine methyl-N-(pyridyl)benzamides

A 3 × 3 isomer grid of nine methyl-N-(pyridyl)benzamides (C13H12N2O) as Mxx (x = para-/meta-/ortho-) has been synthesized and characterised to evaluate and correlate structural relationships from both ab initio calculations (gas-phase, PCM-SMD model solvated forms) and the solid-state. The effect of methyl group (Mx) and pyridine N atom (x) substitution patterns on molecular conformations from calculations and in terms of molecular organisation is evaluated. The primary hydrogen bonding is amideN–H⋯Npyridine in eight isomers but is amideN–H⋯OCamide in Mpm. The N–H⋯N interactions form C(6) chains in the Mxp series, C(5) chains in Mmm, Mom and cyclic centrosymmetric R22(8) rings in the Mxo series. Of note is the short intradimer C–H⋯π(arene) interaction in Moo, one of the shortest reported in a neutral organic system C⋯Cg = 3.3875(18) A, H⋯Cg = 2.46 A [2.33 A] and C–H⋯Cg = 167° [166°] [with normalised C–H distances]. Conformational features and differences between the computational calculations and crystal structures are discussed.

Unusual cone conformation retention in calix[4]arenes

Abstract Use of a regioselective O-alkylation, C-dealkylation synthetic sequence generates an ‘ABAB’ calix[4]arene, 4, which contains only two upper rim t-butyl groups and yet retains the cone conformation. Further substitutions can then be carried out independently on the upper and/or lower rims of the A and/or B subunits, with retention of conformation. Complexation studies show that 4 retains its cone conformation in the presence of alkali metals from sodium to cesium. Thus 4 remains in the cone conformation in solid state, in solution and on complexation.

Synthesis and electrochemical anion recognition by novel redox-responsive ferrocenoyl dipeptide ester derivatives; 1H NMR anion complexation studies

Abstract The synthesis of six N -ferrocenoyl dipeptide ester derivatives FcCOR (Fc=( η 5 -C 5 H 5 )Fe( η 5 -C 5 H 4 ); R=Gly-Gly(OMe) ( 1 ), Leu-Leu(OEt) ( 2 ), Ala-Phe(OEt) ( 3 ), Phe-Phe(OMe) ( 4 ), Phe-Leu(OBn) ( 5 ) and Phe-Ser(OEt) ( 6 )) is described. The electrochemical anion sensing behaviour (using a platinum microdisk working electrode) and 1 H NMR anion coordination studies of these novel pendant N -ferrocenoyl dipeptide ester derivatives with a range of anions are reported.

Copper and nickel complexes of 1,8-disubstituted derivatives of 1,4,8,11-tetraazacyclotetradecane

The stereoselective synthesis of various 1,8-disubstituted derivatives of 1,4,8,11-tetraazacyclotetradecane (cyclam) has been achieved and copper and nickel complexes prepared. For the 1,8-dibutyl derivative, the square-planar nickel(II) complex exists as two diastereoisomers, as revealed by crystallographic analysis. The structure of the copper(II) complex of this ligand confirmed that a strong in-plane ligand field was conserved in square-planar complexes notwithstanding the dialkylation at nitrogen. The structures of the copper(II) complexes of two 1,8-dicarboxymethyl derivatives of cyclam also reveal primary N4 co-ordination with carboxyl oxygens occupying the elongated axial sites. The tricyclic ligand 1,5,8,12-tetraazatricyclo[10.2.2.25,8]octadecane is readily prepared from one of these diacids and the copper complex is kinetically stable in solution with respect to attack by hydrogen sulfide and to acid-catalysed dissociation.