John H. Morris

Copper schiff base complexes with polyfunctional amino acids

Abstract Amino acid Schiff base copper complexes of either salicylaldehyde or 2-hydroxy-1-naphthaldehyde with 1 -serine, 1 -histidine, histamine and 1 -tryptophan have been prepared by constituent combination. The amino acid part of the ligands coordinates to the copper through the carboxylate group and the other available functional group of the amino acids plays a more minor role as a blocking group or in intramolecular bonding. Schiff bases of salicylaldehyde or 2-hydroxy-1-naphthaldehyde with cysteine or penicillamine were prepared. In solution, NMR and IR evidence suggested thiazolidine ring formation in these bases and the presence of two conformers in the salicylidinecysteine base. Bases containing penicillamine produced a stoichiometric Schiffs base copper complex. Cysteine-containing ligands produced a stoichiometric compound with zinc but not with copper. However, with copper and not with zinc, constituent combination produced compounds of general formula, aldehyde (amino acid) 2 (copper) 2 xH 2 O. These latter compounds are believed to contain either cystine or dipenicillamine.

Preparation of substituted derivatives of the octahydrotriborate(1–) ion

Abstract The reactions between the octahydrotriborate(1–) ion, B 3 H − 8 , and mercury(I) halides have produced the substituted anions B 3 H 7 Cl − , B 3 H 6 Cl − 2 and B 3 H 7 Br − . Further treatment of B 3 H 7 Cl − with CN − , SCN − and BH 3 CN − salts yielded the anions B 3 H 7 CN − , B 3 H 7 NCS − and BH 3 CNB 3 H − 7 ,respectively, as the Bu n 4 N + or [Ph 3 P] 2 N + salts. Evidence is also presented for the existence of B 3 H 7 F − formed by the reaction between B 3 H − 8 and Hg 2 F 2 .

Studies of 2,5;6,10;8,10-tri-µ-hydro-nonahydro-nido-nonaborate(1–), [B9H12]–: preparation, crystal and molecular structure, nuclear magnetic resonance spectra, electrochemistry, and reactions

Studies of 2,5;6,10;8,10-tri-µ-hydro-nonahydro-nido-nonaborate(1–)[B9H12]– have involved new syntheses, which have led to crystals suitable for the determination of the X-ray crystal and molecular structure, through reactions of B9H13(SMe2) with [OCN]– or other bases. Crystallographic study of [N(PPh3)2][B9H12] reveals the structure of the anion to be that of a nido-nine-vertex cage, based on the parent bicapped square antiprism with one 5-connected vertex removed. The pentagonal open face is symmetrically bridged by three (µ-H) atoms (two involving the lowest connected boron), conferring effective Cs symmetry upon the polyhedron. Crystals are monoclinic, space group P21/n, with a= 26.759(10), b= 10.340(4), c= 27.044(5)A, β= 103.47(2)°, and Z= 8. Using 6 777 diffracted intensities recorded at 185 K on an Enraf-Nonius CAD4 diffractometer, the structure has been refined to R 0.0847, R′ 0.1216. The 11B, two-dimensional 11B(COSY), and 1H n.m.r. parameters all confirm the structural assignment and the n.m.r. spectra have been assigned unambiguously. Cyclic and a.c. voltammetry and coulometry of [B9H12]– in several solvents at Pt led to the electrochemical parameters and to an isomer-specific electrochemical synthesis of anti-[B18H21]–. Chemically, the [N(PPh3)2]+ salt of [B9H12]– reacted with HCl to give [B9H13Cl]–, whereas the [NBun4]+ salt yielded anti- B18H22; reactions with CF3CO2H gave primarily anti-[B18H21]–.

2-Substituted icosahedral monocarbon carboranes. Part 1. Synthesis via boron insertion

New 2-substituted icosahedral monocarbon carboranes have been synthesised by functionalised boron insertion. The compounds [NBun4][2-Ph-closo-1-CB11H11]1, [PPh4][2-(p-MeC6H4)-closo-1-CB11H11]2, [N(CH2Ph)Me3][2-F-closo-1-CB11H11]3, 2-Me3N-closo-1-CB11H114 and [PPh4][2-Cl(CH2)4O-closo-1-CB11H11]5 were characterised by 1H, 11B and 11B–11B correlation NMR spectroscopy. The crystal structure of 5 shows a cage distortion that is postulated to result from π interaction of the substituent with the cluster. Crystal data: triclinic, space group P, a= 10.672(2), b= 11.047(2), c= 14.203(3)A, α= 75.97(2), β= 87.84(2), γ= 83.22(2)°, Z= 2. Final R= 0.042 for 3951 reflections with I > 2σ(I).

The chromophore in some bis azomethazine Schiff base complexes of nickel

Abstract The effect of substitution on the chromophore in bis azomethazine Schiff base nickel complexes was examined by measuring the electronic spectra of a series of such complexes in chloroform solution. Solid-state spectra of the complexes were similar but less well defined than solution spectra but the definition could be improved by cooling KBr discs containing dispersed complexes to 8 K. On the basis of a CNDO molecular-orbital calculation, the nature of the orbitals likely to produce the observed spectra was defined and band assignments proposed by reference to experimental evidence. It would seem that the lowest energy bands are due to a series of transitions between orbitals which are located mainly on the nickel-to-oxygen bonds but which also contain an appreciable orbital contribution from the aromatic ring system.

Electrochemical and chemical oxidation of [BH3(CN)]– to [BH3(CN)-BH2(CN)]–; electrochemical preparation of [Fe{BH3(CN)}2(NCCH3)4]

The electrolysis of an acetonitrile solution of Na[BH3(CN)] at an iron electrode yields [Fe{BH3(CN)}2(NCCH3)4], but at molybdenum or vanadium anodes Na[BH3(CN)] is oxidised to Na[BH3(CN)BH2(CN)]. Chemical oxidation of Na[BH3(CN)] using either Hg2Cl2 or HgCl2 also gives Na[BH3(CN)BH2(CN)], together with oligomeric BH2(CN) in the case of HgCl2.

1-Me2NH-2-CH2Cl-closo-l-CB11H10. An unusual product from the insertion reaction of Me2NBCl2 with Li2 [7-Me3N-nido-7-CB10H10]

Abstract The boron insertion reaction of Me2NBCl2 with Li2[7-Me3N-nido-7-CB10H10] gave new neutral compound, 1-Me2N(H)-2-CH2Cl-closo-l-CB11H10. The reaction is thought to proceed via a metathetical insertion of Me2NBCl2 into the nido-carborane dianion, accompanied by demethylation of the 7-dimethylamine group and methylene insertion into the B-N bond of the inserted reagent, with concomitant protonation of its nitrogen. Nucleophilic-displacement of dimethylamine by chloride ion and protonation of the C-NMe2 group then gives the observed product, which was characterised by multinuclear NMR spectroscopy and X-ray crystallography.

Methylene insertion into a B-N bond at a cluster surface : crystal structure of 1-Me2N-2-Pri2N(H)CH2-closo-1-CB11H10

Insertion of Pri2NBCI2 into Li2[7-Me3N-nido-7-CB10H10] induces removal of a methyl group from the trimethylamine substituent, methylene insertion into the exo-polyhedral B-N bond and protonation of the diisopropylamino group to give 1-Me2N-2-Pri2N(H)CH2-closo-1-CB11H10, which has been characterised by multinuclear NMR and X-ray crystallography.

Preparation and boron-11 and proton nuclear magnetic resonance study of the anions [B9H14]–, [B9H13(NCS)]–, and [B9H13(NC)BH3]–, and a comparison with the neutral derivatives B9H13(SMe2), B9H13(SEt2), and B9H13(CH3CN); isolation of [B8H12(NCS)]–

The structure and fluxional character of derivatives of [B9H14]– containing anionic or neutral ligands has been investigated by high-field 11B and 1H n.m.r. spectroscopy. The anionic derivatives [B9H13(NCS)]– and [B9H13(NC)BH3]– showed significant dynamic and structural differences from those of the parent ion [B9H14]– or the neutral compounds B9H13(SMe2), B9H13(SEt2), and B9H13(CH3CN). The synthesis of the anionic derivatives led to interesting side-reactions in which [B8H12(NCS)]– was produced and the dual chemical character of [BH3(CN)]– was illustrated as both a two-electron σ-donor ligand and hydride-transfer reagent.

An aromatic Schiff base stabilised as a coordinated enol iminium zwitterion by complex formation with a series of divalent metal ions

The Schiff base N-(2-hydroxy-3-carboxy-1-naphthylidine)-4-methyl-2-sulphonic acid aniline (bonsaH3) has been found to react with a range of divalent metal ions (Mg2+, Mn2+, Co2+, Ni2+ and Zn2+ and UO22+ to give red-yellow insoluble complexes (bonsaH)m(H2O)n. The solid state diffuse reflectance spectra of all the complexes have an intense visible band at ca. 470 nm. This fact, together with evidence from infrared spectra and room-temperature magnetic-moment measurements, suggests that in all cases the ligand is coordinated to the metal ion in the solid state in the enol-iminium zwitterionic form. The 1H NMR spectra of the Mg2+ and Zn2+ complexes in DMSO-d6 indicate that a different structure is adopted in this solvent. Comparisons with the spectra of bonsa-H3 and (bonsa-H2)K·H2O suggest that the solution structure is that of an enol-imine.