Volume 53, Issue 12

In a study preceeding the investigation of a novel class of inclusion compounds, the lowtemperature crystal structure o f the host-m olecule N ,N ’-ditosyl-p-phenylenediamine has been determined. It crystallizes in the monoclinic space group P2 1 /N with two formula units in the unit cell, forming layers of hydrogen-bonded molecules. The essential subunits are rigid phenyl rings and flexible sulfonamide linkages C -N(H)-S(O 2 )-C, the conformations o f which are discussed by comparison with data from the Cambridge Structural Database and based on density functional theory (DFT) as well as semiempirical PM3 calculations for the selected model compounds, N-methyl-methane-, N-methyl-benzene- and N-phenyl-methane-sulfonamide. The torsion angle dependent energy and enthalpy profiles allow estimates o f the rotational barriers around the C -S-N -C bonds. In addition, potential hydrogen bonding by the host molecule is discussed in comparison to analogous carbonic acid derivatives.

Six isostructural inclusion compounds of various ketone and ether guest molecules into the hydrogen-bonded host-matrix of N,N’-ditosyl-p-phenylenediamine are presented. Crystal growth, structure determinations as well as the arrangement within the clathrates formed is reported and discussed in detail. Packing coefficients and especially the volume ratios between the guest-containig channels and the unit cells allow to estimate the size-limit of guest molecules, which can cocrystallize. Additional crystal growth experiments yield information concerning other types of guest molecules, inclusion from solvent mixtures and guest removal as well as guest exchange processes observed for the N,N′-ditosyl-p-phenylenediamine host matrix.

Basic principles of known clathrate inclusion compounds are reviewed and of the novel class discovered with N,N’-ditosyl-p-phenylenediamine as a capable host, three additional molecular aggregates containing five- or six-membered, π- as well as σ-type rings as guests are reported. All of them crystallize in the space group P2 1 /c, but only those of furane and benzene are isostructural, whereas that of dioxane differs in the hydrogen bonding network of the N,N′-ditosyl-p- phenylenediamine host exhibiting sulfonamide / sulfonamide cyclic dimers instead of catemer chains. The low-temperature structures of the crystals are discussed in detail including conformational differences and packing coefficients to gain some insight in their different weathering behavior observed: clathrate cavity inclusion provides more stable crystals than storage of guest molecules within lattice channels

Basic principles of hyrogen-bonding are reviewed including cooperative effects and within the novel class of inclusion compounds formed by N,N′-ditosyl-p-phenylenediamine as a capable host, four aggregates with the hydrogen donor or acceptor guest molecules morpholine, pyridine, N,N-dimethylformamide and dimethylsulfoxide are reported. Morpholine introduces three additional hydrogen bonds N-H···N, N-H···O as well as C-H···O and pyridine, DMF and DMSO each one of type N-H···N, N-H··O(=C) and N-H···O(=S ). Crystallization and structures determined are discussed in detail with special emphasis on the varying sulfonamide conformation as well as on cavity or channel inclusion of the guest molecules. In conclusion, the crystal growth conditions and the structures of the altogether 13 N,N′-ditosyl-p-phenylenediamine inclusion compounds investigated are reviewed and possible reasons for their formation are discussed.

Crystals of K 6 Cu 2 [B 4 PhO 28 (OH) 6 ] were grown under hydrothermal conditions at 160 °C. The crystal structure (monochnic, P2 1 /c (Nr. 14), a = 961.8(1), b = 1755.0(1), c = 942.0(1) pm, β = 112.29(1)°, Z = 2) contains oligomeric tetrahedral anions based on six-membered rings {B 4 P 2 O 10 O 8/2 } with additional branchings by hydrogenphosphate-groups (open branching: 4 x HPO 3 O 1/2 ; cyclic branching: 2 x HPO 2 O 2/2 ). The complex borophosphate anion is represented by the formula [B 4 P 8 O 28 (OH) 6 ] 10- . Cu 2+ is in a tetragonal pyramidal and K + in an irregular coordination by eight and nine oxygen ligands, respectively.

A new series of lanthanide(III) complexes with two novel Schiff-base macrocycles, L 1 and L 2 , containing a N 3 O 4 donor set have been prepared by cyclocondensation of 2,6-bis(2-formylphen-oxymethyl)pyridine and l,2-bis(2-aminophenoxy)ethane or 1,3-bis(2-aminophenoxy)propane, respectively, in the presence of the appropriate metal salt as a template agent. In the absence of the metal salt the macrocycles are not formed. The diamine macrocycles L 3 and L 4 are also formed by reaction of the corresponding diamine and dicarbonyl precursors followed by an in situ reduction with NaBH 4 . Their complexation potential towards Ln(III) ions were also investigated.

Difluorocarbene which is quantitatively eliminated from donor-free bis(trifluoromethyl)- cadmium below 0 °C inserts smoothly into the P-F bonds of PF5 to form (CF 3 ) 3 PF 2 in high yield. Due to the fast conversion of P-Cl bonds into P-F bonds by cadmium fluoride, PCl 5 forms (CF 3 ) 3 PF 2 as well, and a direct synthesis of (CF 3 ) 3 PF 2 with ca. 70 % yield starting from CdEt 2 , CF 3 I and PCl 5 is reported. Whereas no insertion of CF 2 into the axial bonds of (CF 3 ) 3 PF2 has been detected, reaction of (CF 3 )2Cd with (CF 3 ) 3 PCl 2 gives the new tetrakis( haloalkyl)fluorophosphoranes (CF ) 3 (CF 2 C 1 )PF, (CF 3 ) 3 (CFCl 2 )PF, (CF 3 ) 2 (CF 2 Cl) 2 PF and (CF 3 ) 3 (CCl 3 )PF. The NMR spectra of these and related compounds and of their hydrolysis products (CF 3 ) 3 (CF 3-n Cl n )PO are reported. The formation of the higher chlorinated phosphoranes is discussed in terms of an isomerization mechanism presumably involving carbene elimination-reinsertion processes.

In order to obtain suitable precursors for iron complexes that model the reactivity of the active sites of nitrogenases, the coordination chemistry of the [Fe(′N 2 H 2 S 2 ′)] fragment was systematically investigated(′N 2 H 2 S 2 ′ 2- = 1,2-ethanediamine-N,N′-bis(2-benzenethiolate)(2-)). One-pot reactions of FeCl 2 -4H 2 O with the tetradentate amine-thiolate ligand ′N 2 H 2 S 2 ′ 2- and CO, PR 3 or P(OR) 3 yielded the complexes [Fe(CO) 2 (′N 2 H 2 S2′)] (1), [Fe(CO)(PR 3 )(′N 2 H 2 S 2 ′)] (R = Et (2), Pr (3), Bu (4)), [Fe(PMe 3 ) 2 (′N 2 H 2 S 2 ′)] (7), [Fe(dppe)(′N 2 H 2 S 2 ′)] (8 , dppe = 1,2- bis(diphenylphosphine)ethane), and [Fe(P(ÖR) 3 ) 2 (′N 2 H 2 S 2 ′)l (R = Me (9), Pr (10)). Mixed phosphane/phosphite complexes [Fe(PMe 3 )(P(OR) 3 )(′N 2 H 2 S 2 ′)] (R = Me (11), Pr (12)) were synthesized by PMe 3 /P(OPr) 3 exchange of the labile complexes [Fe(PMe 3 ) 2 (′N 2 H 2 S 2 ′)] (7) and [Fe(P(OPr) 3 ) 2 (′N 2 H 2 S2′)] (10). The [Fe(CO)(PR 3 )(′N 2 H 2 S 2 ′)l complexes 3 and 4 also resulted from 1 and PR 3 by photochemical CO substitution. They exhibit characteristic low-frequency v (CO) bands ( ≈1925 cm -1 ), and their remaining CO ligand proved photolytically inert. Reaction of 3 or 4 with NOBF 4 yielded the dinuclear NO complex [Fe(NO)(′N 2 HS 2 ′)] 2 (6 ) which contains two amide functions. Contrary to expectations, [Fe(PR 3 ) 2 (′N 2 H 2 S 2 ′)l complexes could not be obtained with monodentate phosphanes other than PMe 3 . The corresponding N-methylated ligand ′N 2 Me 2 S 2 ,2 - yielded only the complexes [Fe(CO) 2 (′N 2 Me 2 S 2 ′)] (15) and [Fe(′N 2 Me 2 S 2 ′)] (16). X-ray structure analyses of complexes 7, 8 -MeOH, 3, [Fe(CO)(dppm)(′N 2 H 2 S 2 ′)]·0,5 THF (5 ·0,5THF, dppm = bis(diphenylphosphino)methane), and 12·0,5′N2 H 2 S 2 ′-H 2 confirm the pseudo-octahedral coordination of the Fe centers by two trans-S and two cis-N donors and two c/s-coligands. The structural data further suggest that the unexpected instability of the [Fe(PR 3 ) 2 (′N 1 H 2 S 2 ′)] complexes is not caused by steric but by electronic effects. The cyclic voltammograms and the reactivity of the [Fe(L)(L′)(′N 2 H 2 S 2 ′)] complexes corroborate this assumption. The oxidation behaviour of the [Fe(L)(L′)(′N 2 H 2 S 2 ′)] complexes depends critically on the coligands L and L′. Reaction of 1 with dioxygen leads to oxidative dehydrogenation of the ′N 2 H 2 S 2 ′2- ligand and yields the dinuclear Schiff-Base complex [Fe(′gma′ )] 2 (′gma′ 2- = glyoxal-bis(2- mercaptoanil)(2-)). In contrast, oxidation of [Fe(CO)(PR 3 )(′N 2 H 2 S 2 ′)], [Fe(PR 3 ) 2 (′N 2 H 2 S 2 ′)] and [Fe(P(OR) 3 ) 2 (′N 2 H 2 S 2 )] complexes by dioxygen occurs metal-centered and gives the Fe(IV) complexes [Fe(PR 3 )(′N 2 S 2 ′)] (R = Me, Pr), [Fe(P(OR) 3 )(′N 2 S 2 ′)] (R = Me) and [Fe(′N 2 S 2 ′)] 2 that contain the tetraanionic thiolate-amide ligand ′N 2 S 2 ′ 4- .

Tris-thiobenzoates, Arsenic, Antimony, Bismuth Tris-thiobenzoates of arsenic, antimony and bismuth, M(SOCR) 3 have been obtained from their oxides and characterized. In the X-ray crystal structure determinations of these, the group 15 atom and the three covalently bonded sulfur atoms are found to constitute a trigonal pyramid, the central atoms lie at a C 3 axis. In the bismuth complex the thiobenzoate ligand tends to chelate. However, three comparatively short intermolecular M···S interactions are significant features for these molecules resulting in stacking of trigonal prisms providing an essentially six coordinate environment around arsenic and antimony and a nine-coordinate one for bismuth. The structure of PhSb(SOCPh) 2 can be considered

BaCu6Ge2 S8 was synthesized by direct reaction of the elements at 750°C and characterized by X-ray single crystal techniques. The thiogermanate crystallizes in a new orthorhombic structure type (a = 6.122(1) Å, b = 12.084(3) Å, c = 17.614(5) Å; Pbcm, Z = 4). Isolated [GeS 4 ] 4- tetrahedra form a slightly distorted cubic face-centered (fee) arrangement. Baand Cu-atoms each occupy half the octahedral gaps (OG) of this “tetrahedra packing” . Further Cu atoms fill the tetrahedral gaps ( TG) completely. The compound can be written as Ba 2 (1/2OG) (Cu 2 ) 2 (1/2OG) Cu 8 (TG) (GeS 4 ) 4 . Thus the structure of BaCu 6 Ge 2 S 8 can be derived from the Li 3 Bi type. The sulfur coordination of the metal atoms (Cu tetrahedral or trigonal, Ba with CN 8) are realized by the spatial orientation of the [GeS 4 ] 4- tetrahedra. Their centers nearly maintain the fcc-arrangement. This structure interpretation of BaCu 6 Ge 2 S 8 from the viewpoint of a “filled tetrahedra packing” is discussed for further known thiogermanate compounds.

The metalation of tri-terr-butylsilylphosphane with bis[bis(trimethylsilyl)amino]stannylen yields nearly quantitatively the tetrameric tin(II) tri-terf-butylsilylphosphandiide with a central Sn 4 P 4 cubane moiety. Barium bis[tri-tert-butylsilylphosphanide] is accessible via the reaction of tri-tert-butylsilylphosphane with barium bis[bis(trimethylsilyl)amide] in the molar ratio 2 : 1 . This phosphanide reacts with bis[bis(trimethylsilyl)amino]stannylen to give barium tritin(II) tetrakis[μ3-tri-tert-butylsilylphosphandiide]. Crystallographic data of 1: P 2 1 2 1 2 1 , T = 193 K, a = 1532.6(3), b = 2120.2(4), c = 2194.0(5) pm, V = 7.129(3) nm 3 , Z = 4, R, = 0.0360 (9132 observed data [I > 2a( f) ] ) , wR2 = 0.1064 (all data); crystallographic data of 3: P 2 1 /c, T = 193 K, a = 1927.35(1), b = 1799.27(2), c = 2201.35(2) pm, β = 93.010(1)°, V = 7.6234(1) nm3, Z = 4, R 1 = 0.0321 (11993 observed data [I > 2σ(/)]), wR2 = 0.0772 (all data).

The l5N-labelled trimethylstannylamines 1 - 3 [(Me 3 Sn) 3 N, (Me 3 Sn) 2 NPh, (Me 3 Sn) 2 NBCgHi 4 (BCgHi 4 = 9-borabicyclo[3.3.0]nonyn and the non-labelled 4, Me 3 Sn-N(BC 8 Hi 4 ) 2 , were prepared and studied by 1 H, 1 C, 15 N and 119 Sn NMR. The 15 N ultrahigh resolution NMR spectra of 1 revealed otherwise unobserved parameters such as 2 J( 15 N ,Sn , 13 C ) and the isotope induced chemical shift 2 Δ 12/13 C( 15 N). 119 Sn NMR spectra of 1, recorded under similar conditions, also show new parameters such as 3 J( 119 Sn,N,Sn, 13 C) which are not resolved in the non-labelled derivative. By using various types o f two-dimensional heteronuclear shift correlations, absolute coupling signs of 1 J( 119 Sn, 15 N) (all < 0) in 1 - 3 were determined. By the same techniques it proved possible to confirm the negative sign o f :7(Sn,Sn) (-195.4 Hz) in 1. In contrast, the coupling constants 2 J(Sn,Sn) for 2 (+71.7) and 3 (+62.0) possess a positive sign. This sign inversion, observed here for the first time for apparently similar compounds, demonstrates the enormous influence of substituents on the nature of the lone pair of electrons at the nitrogen atom. It also shows that these experiments for sign determinations of coupling constants are necessary in order to interpret these data correctly.

The reaction of cis-(Ph 3 P) 2 PtCl 2 with BOC-N-glycine and FMOC-N-alanine gives the carboxylate coordinated complexes cis-(Ph 3 P) 2 Pt(Cl)(O 2 CCH 2 NHBOC) (1) and cis- (Ph 3 P) 2 Pt(Cl)(O 2 CC(H)(Me)NHFMOC (2). Chloride and proton abstraction from 1 affords the N,O-chelate complex (Ph 3 P) 2 Pt(O 2 CCH 2 NBOC) (3). From the chloro-bridged compounds [Cp*MCl 2 ] 2 (M = Rh, Ir), [(p-cymene)RuCl 2 ] 2 and BOC-N-L-MetGlyOH (L) the compounds Cp*M(Cl) 2 L (4, 5) and (p-cymene)Ru(Cl) 2 L (6 ) with the mono-dentate dipeptide are obtained which in the presence of NaOMe form O,N,S-bis(chelate) complexes 7 - 9 . The X-ray diffraction analysis of the iridium O,N,S chelate complex 8 shows a five membered and a seven membered chelate ring.

The phosphenium complexes Cp(OC) 2 W=PR 2 [R = Ph, o-Tol, Me, t-Bu, (2a -d)] react with 2,3-dimethyl-1,3-butadiene (3) via [4+2]-cycloaddition to form the phosphametallacyclohexe­ nes Cp(OC) 2 W-PR 2 -CH 2 -CMe=CMe-CH 2 (4a -d). The structure of 4a has been determined by X-ray diffraction.

Molecular recognition between Rebek’s cleft R and 4-(2-benzimidazolyl)-aminomethyl-2,6-di-rm-butyl-phenol (Bi) is investigated by means of EPR spectroscopy. Their specific inter-molecular interactions are distinguished from non-specific interactions represented by mere protonation on addition of benzoic acid. Both interactions are related to intramolecular in­ terconversions at the C ∞ -atom of Bi*, where a two-jump mechanism is found for free and protonated Bi* and a two-site exchange for the complexed ligand. While NMR spectroscopy indicates the existence of 1:1 and 1:2 receptor-substrate complexes, the faster time scale of EPR spectroscopy allows to identify one 1 : 2 as well as three 1 : 1 associates and to elucidate their formation conditions. Based upon the corresponding hf parameters, binding modes and sites are proposed for the key-in-the-lock system.

The synthesis of the four stereoisomers of β-hydroxyhistidine and their analytical identifi­ cation is reported.

LiI-3THF was obtained from the reaction of tmp 2 AH (tmp = tetramethylpiperidino) with Li-AsHPh in toluene/THF. It is more, conveniently prepared from LiH and iodine in THF. It forms molecule in the lattice, the Li ion being tetracoor-dinated in a slightly distorted tetrahedral fashion.

Benzo-18 -crown-6 -Acetonitrile (1/2), Crystal Structure Single crystals of the title complex resulted fortuitously during an attempt to co-crystallise MeN(SO 2 Me) 2 with benzo-18-crown-6 from an MeCN solution at -30 °C. The crystal structure has been determined via data collection at -100 °C (monoclinic, space group P2 1 /n, Z = 4). The nitrile molecules are located with their me­ thyl groups above and below the plane of the 18-membered crown ring, the Me hydrogen atoms being rotationally disordered about the MeCN axes; C(methyl)···O(crown) distances range from 309.4(3) to 384.9(3) pm.