Axial Chloride Research Articles

Formation of a highly oxidized iron biliverdin complex upon treatment of a five-coordinate verdoheme with dioxygen.

Treatment of a green solution of the five-coordinate octaethylverdoheme, XFeII(OEOP) 1 (X = Cl or Br), with dioxygen results in the formation of a new iron complex of octaethylbiliverdin, 2, within a matter of minutes. The reaction has been monitored by 1H NMR spectroscopy, and the product 2 (X = Cl) has been isolated and examined by X-ray crystallography. The structure of 2 (X = Cl) shows that the iron is five-coordinate with bonds to the four nitrogen atoms of the helical tetrapyrrole ligand and to an axial chloride. Treatment of 2 (X = Cl or Br) with zinc amalgam produces the known iron(III) complex of biliverdin, {FeIII(OEB)}2. The unusual pattern of resonances in the 1H NMR spectrum of 2 and its facile reduction to {FeIII(OEB)}2 indicate that 2 is an oxidized complex that can be formulated by resonance structures involving either an Fe(IV) ion bound to a bilindione trianion or an Fe(III) ion bound to an oxidized, dianionic, radical form of the ligand.

A critical look on the nature of the intra-molecular interligand π,π-stacking interaction in mixed-ligand copper(ii) complexes of aromatic side-chain amino acidates and α,α′-diimines

The mixed ligand complexes {[Cu(4Cl-Phe)(bpy)(H2O)]Cl·[Cu(4Cl-Phe)(bpy)Cl]·2H2O} (1) and [Cu(4HPG)(bpy)]·2H2O (2) were synthesized and their crystal structures determined by X-ray crystallography (4Cl-Phe = D,L-4-chlorophenylalaninato, 4HPG = D-4-hydroxyphenylglycinato, bpy = 2,2′-bipyridine). The asymmetric unit of crystals of 1 consists of two slightly different Cu(II) complexes-one contains an axial water ligand, whereas the second one has a chloride anion at that position. By contrast, 2 exhibits two close similar molecules, both having axial chloride ligands, and non coordinated water. The geometrical parameters for π,π-stacking interactions were determined by an application of PLATON program. Intermolecular π,π-interaction between bpy ligands on adjacent Cu(II) moieties results in homo pairs of complexes in the case of 1. In addition, both species of compound 1 exhibit intramolecular interligand π,π-interaction between the 4Cl-phenyl ring of 4Cl-Phe and the metalloaromatic Cu–bpy chelate ring. In crystal 2, multi-stacked homo chains are formed. Analogous calculations for previously reported, related compounds, similar to those presented here, revealed that in most cases with intra-molecular interligand π,π-interaction there is an efficient “aryl–metal chelate ring” π,π-stacking instead of an aryl–aryl interligand π,π-interaction, which indeed is not observed. These findings let us to take a critical look at the nature of the intramolecular interligand π,π-stacking interaction in the referred copper(II) mixed-ligand complexes.

Crystal Structure of trans- [ReCl2(dppp)2]Cl · ½H2O (dppp = 1,3-bis(diphenylphosphino)propane)

The crystal structure of trans-[ReCl2(dppp)2]- Cl · ½H2O (dppp = 1,3-bis(diphenylphosphino)- propane), a potentially useful radiopharmaceutical agent, was determined by single crystal X-ray diffractometry. It belongs to the tetragonal space group P4̄ with Z = 2. The Re(III) ion is in a quasioctahedral environment coordinated to a pair of symmetry related dppp molecules, acting as bidentate ligands, and two axial chloride ions.

1,4-Bis(pyridyl-2-ylmethyl)-1,4-diazacycloheptane]chlorocobalt(II) perchlorate

The crystal structure of a CoII complex with 1,4-di­aza­cyclo­heptane (DACH) functionalized by two additional pyridine donor pendants, [CoCl(L)](ClO4), where L = 1,4-bis­(pyridyl-2-yl­methyl)-DACH (C17H22N4), has been determined by X-ray diffraction analysis. In the mononuclear complex, the CoII center is pentacoordinated by the four nitro­gen donors of the ligand and one axial chloride anion, resulting in a coordination sphere intermediate between ideal square-pyramidal and trigonal bipyramidal. It forms a one-dimensional linear structure through intermolecular C—H⋯Cl and C—H⋯O hydrogen-bonding interactions.

Heavy atom effect on nonlinear absorption and optical limiting characteristics of 5,10,15,20-(tetratolyl) porphyrinato phosphorus (V) dichloride

Optical limiting performance and third-order nonlinearity χ (3) are investigated in 5,10,15,20-(tetratolyl) porphyrinato phosphorus (V) dichloride ([(TTP)P VCl 2] +). Heavy atom effect exerted by the two axial chlorides is found to result in low fluorescence yield (∅ fl), shorter lifetimes of S 1,T 1 and faster intersystem crossing (ISC), leading to larger excited state absorption (ESA) from T 1→T n . This phenomenon is found to lower the limiting threshold by 30 times and increase the second hyperpolarizability by one and three orders in ps and ns time regimes, respectively.

The reactivity of ruthenium mono(bipyridine) carbonyl complexes in an alcoholic solution of alkali metal carbonates

Chlorine containing ruthenium bipyridine carbonyl compounds react readily in dilute alkaline solutions under a CO atmosphere affording a poorly soluble and air sensitive product that is suggested to have a polymeric nature. Various analysis methods (MS and TPD) were used in the characterisation of the product. The replacement of the axial chloride ligands in trans(Cl), cis(CO)[Ru(bpy)(CO) 2Cl 2] and [Ru(bpy)(CO) 2Cl] 2 is proposed to be the initial step in the polymerisation. The replacement of chlorides in methanolic solution was confirmed by isolating and characterising the dimeric intermediate [Ru(bpy)(CO) 2(COOCH 3)] 2.

Structural and spectral investigation on the CoII complexes with 1,4-diazacycloheptane (DACH) functionalized by heterocyclic pendants

A series of penta-coordinated CoII complexes of 1,4-diazacycloheptane (DACH) functionalized by additional imidazole or pyridine donor pendants, [CoL1Cl](ClO4)·H2O (1), [CoL2Cl](ClO4) (2) and [CoL3Cl](ClO4)·CH3OH (3), where L1=1,4-bis(imidazole-4-ylmethyl)-DACH, L2=1,4-bis(N-1-methylimidazol-2-ylmethyl)-DACH and L3=1,4-bis(pyridyl-2-ylmethyl)-DACH have been synthesized and characterized by elemental analyses, IR and UV–Vis spectra. In all the mononuclear complexes, each CoII center is penta-coordinated to four nitrogen donors of the ligand and one axial chloride anion. The crystal structure of complex 2 has been determined by X-ray diffraction analysis, which forms a one-dimensional linear structure through inter-molecular C–H⋯Cl and C–H⋯O hydrogen-bonding.

Preparation and structural characterization of mercury 21-thiaporphyrin complex: Hg II(Stpp)Cl (Stpp=tetraphenyl-21-thiaporphyrin anion)

Treatment of tetraphenyl-21-thiaporphyrin (StppH) with Hg(OAc) 2 in CH 2Cl 2 yields diamagnetic Hg II(Stpp)Cl complex. The coordination sphere around Hg 2+ in the monomeric molecule is described as a five-coordinate distorted trigonal bipyramid with the bonding to the three pyrrole nitrogens [Hg(1)–N=2.104(4), 2.626(4), 2.640(4) Å], the thiophene sulfur [Hg(1)–S=2.801(1) Å], and one axial chloride ligand [Hg(1)–Cl(1)=2.318(1) Å]. The plane of the three pyrrole nitrogen atoms [i.e., N(1), N(2), N(3)] bonded to Hg 2+ is adopted as a reference plane 3N. Because of its larger size, the Hg 2+ is considerably out of the 3N plane; its displacement of 1.41 Å is in the same direction as that of the apical Cl − ligand. The thiophene ring is slightly folded so that the dihedral angle between the C(13)–C(14)–C(15)–C(16) and C(13)–S(1)–C(16) planes is 7.3°.

Synthesis, X-ray structure, electrochemical, and EPR studies of a pentacoordinated mn(II) tetramethylcyclam complex.

The synthesis and full characterization of [(tmc)MnCl]·X (where tmc is 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane and X is BPh4- or BF4-) are reported. The complex is of type I geometry. The manganese ion is pentacoordinated by the four tertiary nitrogen atoms of the macrocycle and one axial chloride. Variable-temperature magnetic susceptibility data indicate that the oxidation state of the manganese ion is +II with S = 5/2. The EPR spectrum exhibits unusual signals, with the main derivative line at g = 3.7 and transitions at more than 900 mT. The cyclic voltammogram of this derivative consists of two reversible systems at +1.14 and +1.36 V vs SCE related by a chemical equilibrium attributed to an isomerization process.

Trans-Dichloro(meso-2,3,7,11,12-pentamethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene-κ4N3,7,11,17)rhodium(III) hexafluorophosphate

In the title compound, [RhCl2(C18H32N4)]PF6, the RhIII ion lies at the centre of a distorted octahedron of two axial chloride and four equatorial aza ligands. Within estimated error, the complex cation possesses non-crystallographic mirror symmetry. The Rh—Cl distances of 2.345 (3) and 2.349 (3) A are equivalent, as are the three Rh—Nsp3 distances [mean 2.145 (7) A]. The Rh—Nsp2 distance is much shorter at 1.964 (7) A, reflecting the different hybridization of this donor atom. The four N atoms are not coplanar, and the metal ion lies out of the N4 plane by 0.013 (3) A, suggesting that, with an ionic radius of 0.805 A, the RhIII ion is somewhat large for the macrocyclic cavity.

Products of the reactions of [Re 2X 8] 2– with 3,6-dithiaoctane (dto). Preparation and crystal structures of Re 2Cl 5(dto) 2, Re 2Br 5(dto) 2, and ( n-Bu 4N) 2Re 2(NCS) 8·dto

The reactions of the quadruply bonded complexes ( n-Bu 4N) 2Re 2X 8 (X=Cl, Br) with excess 3,6-dithiaoctane (CH 3CH 2SCH 2CH 2SCH 2CH 3 or dto) under forcing conditions lead to the compounds Re 2Cl 5(dto) 2 ( 1) and Re 2Br 5(dto) 2 ( 2) with Re–Re triple bonds. X-ray crystallographic studies of compounds 1 and 2 reveal a common staggered, unsymmetrical molecular geometry with both dto ligands chelated to the same metal atom. This Re atom is also bonded to a single axial halide ligand, while the other four halides surround the second Re atom. In contrast to the only previous example of this type of dirhenium compound, Re 2Cl 5(dithiahexane) 2, there is no sharing of axial chloride ligands between molecules in the crystal lattices of 1 and 2. The Re–Re bond distances are 2.2772(8) and 2.2826(6) Å in 1 and 2, respectively. Magnetic measurements, cyclic voltammetry, and IR, Vis and ESR spectra of 1 and 2 are reported. Addition of dto to a solution of ( n-Bu 4N) 2Re 2(NCS) 8 leads to the formation of ( n-Bu 4N) 2Re 2(NCS) 8·dto ( 3). Crystallographic studies show 3 to consist in the solid state of chains of [Re 2(NCS) 8] 2– units linked together by dto molecules with each dto sulfur atom weakly coordinated to axial sites on Re atoms of different anions. The Re–Re quadruple bond distance in 3 is 2.2854(3) Å.

The synthesis, crystal structure, and spectroscopic characterization of a tetrakis(μ- N, N′-diarylformamidinato)chlorodirhenium(III,III) cationic complex

A variety of dirhenium compounds has been synthesized with (ArNC(H)NAr) − where Ar is a substituted C 6H 5 or C 6H 4 aryl ring with different electron withdrawing and electron donating substituents. Reactivity studies of AgBF 4 with tetrakis(μ- N,N′-diarylformamidinato)dichlorodirhenium(III,III) complex with a p-MeO substituted aryl ring result in the loss of a single axial chloride from the Re 2Cl 2(III,III) species to yield a cationic complex, [Re 2Cl[( p-MeOC 6H 4)NCHN( p-MeOC 6H 4)] 4][BF 4] and AgCl. The X-ray crystal structure, UV–Vis and NMR spectroscopy, and electrochemical characterization of the cationic Re 2Cl(III,III) derivative [Re 2Cl[( p-MeOC 6H 4)NCHN( p-MeOC 6H 4)] 4][BF 4] are compared to the parent neutral Re 2Cl 2(III,III) complex, Re 2Cl 2[( p-MeOC 6H 4)NCHN( p-MeOC 6H 4)] 4.

A New Linear Tricobalt Compound with Di(2-pyridyl)amide (dpa) Ligands: Two-Step Spin Crossover of [Co3(dpa)4Cl2][BF4

Chemical oxidation of the linear tricobalt compound Co3(dpa)4Cl2 (1) with 1 equiv of NOBF4 yields the one-electron oxidized species [Co3(dpa)4Cl2]+ (1+), which crystallizes from dichloromethane as a solvate [Co3(dpa)4Cl2][BF4]·2CH2Cl2 (2·2CH2Cl2). The crystal structure of 2·xCH2Cl2 (with x varying from 1.125 to 2.0) has been determined at 100, 213, and 300 K, showing very little variation and an essentially symmetrical arrangement of three Co atoms in the cation 1+ with Co−Co distances of 2.3168(8) and 2.3289(8) A. The terminal cobalt to axial chloride distances are 2.350(1) and 2.376(1) A at 100 K. The cation maintains its symmetrical structure at ambient temperature (300 K) with only a slight lengthening (0.01−0.02 A) of Co−Co and Co−N distances. Temperature studies of the magnetic properties for 2 in both solution and solid state have revealed a spin-crossover behavior occurring in two gradual steps, indicating that 2 exhibits a diamagnetic ground state and thermally accessible triplet and quintet spin...

Metal-Metal Bonding in M(2)Cl(6)(H(2)PCH(2)PH(2))(2), M(2)Cl(6)(PH(3))(4), and M(2)Cl(10)(4-) (M = Cr, Mo, W) Edge-Shared Dimer Systems.

Density functional theory is used to determine the electronic structures, geometries, and periodic trends in metal-metal bonding in the homo- and heterobimetallic d(3)d(3) edge-shared systems M(2)Cl(10)(4-), M(2)Cl(6)(PH(3))(4), and M(2)Cl(6)(H(2)PCH(2)PH(2))(2) (M = Cr, Mo, W). The much shorter metal-metal distances in these complexes relative to M(2)Cl(10)(4-) (M = Mo, W) are shown to arise solely from electronic differences between chlorine and phosphine donors. Due to inversion of the delta and delta orbitals, the complexes M(2)Cl(6)(PH(3))(4) and M(2)Cl(6)(H(2)PCH(2)PH(2))(2) (M = Mo, W) are found to possess formal metal-metal double bonds. The periodic trends in metal-metal bonding in these systems are rationalized in terms of the energetic contributions of orbital overlap (DeltaE(ovlp)) and spin polarization (DeltaE(spe)). The reduction in DeltaE(spe) and increase in DeltaE(ovlp) on replacement of axial chlorides with phosphine both favor stronger metal-metal bonding in the phosphine-based complexes. The strong linear dependence observed between DeltaE(spe) and DeltaE(ovlp) enables the metal-metal bonding in these systems to be predicted simply from single-ion spin-polarization energies. The antiferromagnetic coupling in M(2)Cl(6)(H(2)PCH(2)PH(2))(2) (M = Mo, W) and MoWCl(6)(H(2)PCH(2)PH(2))(2) is shown to be mostly due to coupling of the metal delta electrons, with a smaller contribution from the pi electrons, particularly for the dimolybdenum complex.

Synthesis, structure and magnetic behavior of a di-μ-chloro-di-μ-imidazolato-tetracopper(II) complex with two dinucleating macrocycles

The synthesis, crystal structure and magnetic behavior of the di-μ-chloro-di-μ-imidazolato-tetracopper(II) complex [L 2Cu 4(Im) 2Cl 2](ClO 4) 4(CH 3OH), where Im is imidazole and L is 3,6,9,17,20,23-hexaazatricyclo[23.3.1.1 11,13]triaconta-1(29),11(30),12,14,25(26),27-hexaene, have been studied. X-ray structure analysis shows that the compound crystallizes in monoclinic and space group P2(1)/ c, with a=13.716(3), b=11.165(2), c=27.340(6) Å, β=98.43(3)° and Z=2. The cation consists of two imidazolate bridged dicopper(II) centers encapsulated within two macrocycles, respectively, which are linked by a pair of chloride atoms. In each imidazolate bridged dicopper(II) center, both copper atoms are five-coordinated by four basal nitrogen atoms (three from the macrocycle and one from the imidazolate) and one axial chloride atom shared with another copper atom in the other imidazolate bridged dicopper(II) center in the molecule. pH-dependent ESR studies of the title complex in frozen 50% aqueous DMSO solution show that the bridged cation [LCu 2(Im)] 3+ exists as a major species in solution over the range 7.00≤pH≤11.5, and the μ-Im bridge is broken in the pH range of 7.00–5.20. The molar conductance of the title complex indicates that the μ-Cl bridge is almost entirely dissociated when dissolved in 1:1 DMSO aqueous solution. However, when Cl − ions were gradually added to the solution, a complex with a CuN 4Cl chromophore was successively formed. Magnetic measurement studies on the powder sample reveal that antiferromagnetic interactions are mediated through both μ-Im ( J 1=−26.78 cm −1) and μ-Cl ( J 2=−9.52 cm −1) bridges.

A very short Re26+ quadruple bond: first DFT calculations on a paddlewheel complex with an element of the third transition series

The first complexes containing third row transition elements with bridging hpp (the anion of 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine) are presented. Re2(hpp)4Cl2, 1, is a typical paddlewheel complex with two axial chloride ions. The Re–Re distance in 1 of 2.191(1) A is one of the shortest known for a quadruply-bonded Re26+ complex and the Re–Cl distance of 2.749(5) A is the longest one reported for this type of complex. The second compound, Re2(hpp)3Cl3, 2, has three bridging hpp ligands, two equatorial chloride ions and one axial chloride ion. The Re–Re distance is 2.189(2) A. The electronic structure of 1 has been determined by DFT calculations, the first time this has been done on a paddlewheel complex containing a third row transition element.

Reaction of Octachlorodirhenate with a Redox-Active Tetrathiafulvalene Phosphine Ligand: Spectroscopic, Magnetic, and Structural Characterization of the Unusual Paramagnetic Salt [ReCl(2)(o-P2)(2)][Re(2)Cl(6)(o-P2)] (o-P2 = o-{P(C(6)H(5))(2)}(2)(CH(3))(2)TTF).

Reaction of [(n-Bu)(4)N](2)[Re(2)Cl(8)] with the tetrathiafulvalene phosphine ligand o-{P(C(6)H(5))(2)}(2)(CH(3))(2)TTF (o-P2) in refluxing ethanol produces the mixed-nuclearity salt [ReCl(2)(o-P2)(2)][Re(2)Cl(6)(o-P2)] (1.2), composed of the mononuclear Re(III) complex (1) and the mixed-valence Re(II)-Re(III) dinuclear anion (2). The complex crystallizes as a CH(2)Cl(2) solvate in the triclinic space group P&onemacr;, a = 13.4559(1) Å, b = 20.4015(3) Å, c = 21.5538(1) Å, alpha = 88.261(1) degrees, beta = 72.987(1) degrees, gamma = 84.933(1) degrees, and Z = 2. The molecular cation consists of two trans o-P2 ligands in the equatorial plane and axial chloride ligands. The dinuclear anion adopts an eclipsed geometry with an unsymmetrical coordination environment for the two metal atoms; one Re(II) center is coordinated to a chelating o-P2 ligand and two chlorides while the other Re atom is coordinated to four chloride ligands. The dinuclear portion of the salt is a monoanion which leads to a formal bond order assignment of 3.5, based on the fact that the molecule possesses an Re(2)(5+) core. The salt was further characterized by infrared and electronic spectroscopies, electrochemistry, and variable temperature magnetic susceptibility; the presence of the individual ions in bulk samples was verified by positive and negative FAB mass spectrometry. Isolation of the two separate ions was achieved by treatment of the salt with Co(C(5)H(5))(2), which reduces the Re(III) cation to the Re(II) complex ReCl(2)(o-P2)(2) (3). This neutral compound was separated from the byproduct salt [Co(C(5)H(5))(2)][Re(2)Cl(6)(o-P2)] and reoxidized with CCl(4)/CH(2)Cl(2) or NOBF(4) to produce [ReCl(2)(o-P2)(2)][Cl] (1.[Cl]) and [ReCl(2)(o-P2)(2)][BF(4)] (1.[BF(4)]), respectively. Compounds 3, 1.[Cl], and 1.[BF(4)] were identified by a combination of infrared spectroscopy, mass spectrometry, and cyclic voltammetric measurements. Variable temperature dc susceptibility studies of [ReCl(2)(o-P2)(2)][Re(2)Cl(6)(o-P2)] (1.2) revealed classical Curie paramagnetic behavior (with a Curie constant equal to 0.395) and a large temperature independent paramagnetic contribution (chi(TIP) = 9.64 x 10(-)(3) emu/mol). The EPR spectrum of 1.2 consists of a broad, complex signal due to hyperfine interactions to both isotopes (185,187)Re (I = (5)/(2)) and (31)P (I = (1)/(2)) which is typical for paramagnetic metal-metal bonded dirhenium phosphine compounds.

Syntheses and structures of some Ru 25+ complexes containing weakly coordinating anions as axial ligands

The dehalogenation reactions of Ru 2 5+ complexes containing axial chloride ions with silver salts of weakly coordinating anions are described, illustrating the conditions under which the title compounds can be prepared. The reaction between Ru 2(O 2CEt) 4Cl and AgX yields the compounds Ru 2(O 2CEt) 4X ∞(XCF 3SO 3 − ( 1), ClO 4 −, ( 2)); that between Ru 2(O 2CR) 4Cl and AgBF 4 yields [Ru 2(O 2CR) 4]-[BF 4] (RMe ( 3), Et ( 4)); and when Ru 2(chp) 3(O 2CMe)Cl (Hchp=2-chloro-6-hydroxypyridine) is reacted with AgCF 3SO 3, Ru 2(chp) 3(O 2CMe)CF 3SO 3 ( 5) results. When Ru 2(chp) 3(O 2CMe)Cl is reacted with [Ag(NCMe) 4][BF 4] instead, [Ru 2(chp) 3-(O 2CMe)(NCMe)][BF 4] ( 6) results, and when Ru 2(chp) 4Cl is reacted with wet AgX, [Ru 2(chp) 4(OH 2)][X] (XBF 4 − ( 7), CF 3SO 3 − ( 8)) are the products obtained. When 3 is subsequently reacted with 1 equiv. of pyridine, pyRu 2(O 2CMe) 4BF 4 ( 9) is isolated, and when 4 is reacted with either THF or water, [Ru 2(O 2CEt) 4(L) 2][BF 4] (LTHF ( 10), H 2O ( 11)) are the products. The structures of compounds 1, 2, 5 and 9 as determined by single crystal X-ray diffraction are described.

Synthesis, characterization and solution 113Cd NMR analysis of Cd(II) 1,4,7,10,13-pentaazacyclopentadecane complexes

Two new cadmium(II) complexes of the macrocyclic ligand, 1,4,7,10,13-pentaazacyclopentadecane 5, have been prepared and characterized. The crystal structure of dichlorocadmium(II) complex 3 was determined and reveals that the Cd(II) is coordinated in a pentagonal bipyramidal array of the five nitrogens of the macrocyclic ring and capped by two trans-chloro ligands. Crystal data for Cd(C 10H 25N 5)Cl 2–0.5H 2O are as follows: monoclinic at 20 °C, space group C2/c−C 6 2h (No. 15) with a =22.165(5) Å, b =11.439(3) Å, c =14.6788(4) Å, β=118.75(2)°, V=3262(2) Å 3 and Z=8 [ d calcd=1.660 g cm −3; μ a(Mo K α)=1.66 mm −1]. Solution 1H, 13C and 113Cd NMR studies of complex 3 suggest that in non-polar solvents, such as CDCl 3, the seven-coordinate structure is maintained, while in aqueous media dissociation of one axial chloride ligand affords a macrocyclic ligand-folded six-coordinate species. This is analogous to the dichloromanganese(II) complex 1. Folding of the pentaazamacrocyclic ligand 5 is confirmed as a relevant structural motif for this series of complexes by the X-ray structure determination of the bis(nitrate) derivative. Complex 4 [Cd(C 10H 25N 5)NO 3]NO 3 reveals a six-coordinate structure with a folded conformation of the macrocyclic ligand. Crystal data for [Cd(C 10H 25N 5)NO 3]NO 3 is as follows: orthorhombic at 20 °C, space group P2 12 12 1−D 4 2 (No. 19) with a =9.627(2) Å, b =12.858(2) Å, c =14.003(2) Å, V=1733.3(6) Å 3 and Z=4 [ d calcd=1.731 g cm −3; μ a(Mo K α)=1.30 mm −1]. Solution 1H, 13C and 113Cd NMR studies of complex 4 suggest six-coordinate structures in both CDCl 3 and D 2O, again with the macrocyclic ligand in a folded conformation. Again, this is entirely analogous to the Mn(II) bis(nitrate) complex 2. 113Cd NMR shifts are consistent with literature predictions for the types and numbers of coordinating ligands in complexes 3 and 4 in both NMR solvents.

Lateral, Chiral Tin(IV) Porphyrin Assemblies

The μ-Oxo stacks of tin(IV) porphyrins rearrange to staircase-type and lateral aggregates upon replacement of the oxygen ligands by chloride ions. The lateral aggregation of tin(IV) 2,18-dipropionate porphyrins in hydrochloric acid at pH 0–0.5 is favoured by 8,13-ethyl groups instead of the natural 8,13-vinyl groups of protoporphyrin IX and is impeded by hydrogen atoms at these positions. Replacement of axial chloride counterions to the tin(IV) central ions by cyanate counterions at pH 4.5 leads to similar aggregates if the cyanate ions are connected by hydrogen bonding to acetic or lactic acid. In this case, aggregation is not necessarily impeded by hydrogen atoms at positions 8 and 13. D- and L-lactic acid enforce chiral assemblies of the tin(IV) deuteroporphyrin 1a with mirror image CD (circular dichroism) spectra (θ ≈ 8 × 105deg cm2dmol−1), whereas the gluconoyl hydrazide-substituted tin(IV) deuteroporphyrin 1d does not form aggregates at all.