On the Structure and Role of Avian Eggshells: A 31P, 1H, and 13C Solid-State NMR Study.

The eggshell is a composite and highly ordered structure formed by biomineralization. Besides other functions, it has a vital and intricate role in the protection of an embryo from various potentially harsh environmental conditions. Solid-state nuclear magnetic resonance (SSNMR) has been used for detailed structural investigations of the chicken, tinamou, and flamingo eggshell materials. 31P NMR spectra reveal that hydroxyapatite and ß-tricalcium phosphate in the ratio 3:2 represent major constituents of phosphate species in the eggshells. All three eggshells exhibit similar spectra, except for the line widths, which implies different structural order of phosphate species in the chicken, tinamou, and flamingo eggshells. 1H NMR spectra for these materials are comparable, differentiating overlapped peaks in three spectral regions at around 7, 4-5, and 1-2 ppm. These spectral regions have been attributed to protons from NH or CaHCO3, water, and possibly isolated monomeric water molecules or hydroxyl groups in calcium-deficient hydroxyapatite. 1H-13C CP MAS NMR revealed the presence of organic matter in the form of lipids and proteins. Two overlapped resonances in the carbonyl region at around 173 and 169 ppm are assigned to the carbonyls of the peptide bonds and the bicarbonate unit in calcite, respectively. Fourier-transform infrared spectroscopy (FTIR) spectra confirmed the presence of structural units detected in the NMR spectra.

Correction: Unexpected arene ligand exchange results in the oxidation of an organoruthenium anticancer agent: the first X-ray structure of a protein-Ru(carbene) adduct.

Correction for 'Unexpected arene ligand exchange results in the oxidation of an organoruthenium anticancer agent: the first X-ray structure of a protein-Ru(carbene) adduct' by Matthew P. Sullivan et al., Chem. Commun., 2018, 54, 6120-6123.

Unexpected arene ligand exchange results in the oxidation of an organoruthenium anticancer agent: the first X-ray structure of a protein-Ru(carbene) adduct.

The first X-ray structures of adducts formed between a RuII(N-heterocyclic carbene)(η6-p-cymene) compound and a protein are reported. Coordination to the protein induced the cleavage of the cymene ligand and EPR spectroscopy demonstrated the oxidation of the Ru centre.

Oligo-nuclear silver thiocyanate complexes with monodentate tertiary phosphine ligands, including novel 'cubane' and 'step' tetramer forms of AgSCN : PR3 (1:1)4.

Adducts of a number of tertiary pnicogen ligands ER(3) (triphenyl-phosphine and -arsine (PPh(3),AsPh(3)), diphenyl,2-pyridylphosphine (PPh(2)py), tris(4-fluorophenyl)phosphine (P(C(6)H(4)-4F)(3)), tris(2-tolyl)phosphine (P(o-tol)(3)), tris(cyclohexyl)phosphine (PCy(3))), with silver(I) thiocyanate, AgSCN are structurally and spectroscopically characterized. The 1:3 AgSCN : ER(3) complexes structurally defined (for PPh(3),AsPh(3) (diversely solvated)) take the form [(R(3)E)(3)AgX], the thiocyanate X = NCS being N-bound, thus [(Ph(3)E)Ag(NCS)]. A 1:2 complex with PPh(2)py, takes the binuclear form [(pyPh(2)P)(2)Ag()Ag(PPh(2)py)(2)] with an eight-membered cyclic core. 1:1 complexes are defined with PPh(2)py, P(o-tol)(3) and PCy(3); binuclear forms [(R(3)P)Ag()Ag(PR(3))] are obtained with P(o-tol)(3) (two polymorphs), while novel isomeric tetranuclear forms, which may be envisaged as dimers of dimers, are obtained with PPh(2)py, and, as further polymorphs, with PCy(3); these latter may be considered as extensions of the 'cubane' and 'step' forms previously described for [(R(3)E)AgX](4) (X = halide) complexes. Solvent-assisted mechanochemical or solvent-assisted solid-state synthesis methods were employed in some cases, where complexes could not be obtained by conventional solution methods, or where such methods yielded a mixture of polymorphs unsuitable for solid-state spectroscopy. The wavenumbers of the ν(CN) bands in the IR spectra are in broad agreement with the empirical rule that distinguishes bridging from terminal bonding, but exceptions occur for compounds that have a double SCN bridged dimeric structure, and replacement of PPh(3) with PPh(2)py apparently causes a significant decrease in ν(CN) to well below the range expected for bridging SCN in these structures. (31)P CP MAS NMR spectra yield additional parameters that allow a correlation between the structures and spectra.

Solvent-assisted mechanochemistry.

The literature on solvent-assisted mechanochemistry is reviewed with a view to linking observations concerning the applicability of the technique to theories of its mechanism, and summarizing the advantages and limitations of the technique when applied to a variety of different reaction types. Previously unnoticed links between "solvent-free" and solvent-assisted reaction mechanisms are presented, and reasons why the method should be considered more widely by synthetic chemists are given.

Mechanochemical and solution synthesis, X-ray structure and IR and 31P solid state NMR spectroscopic studies of copper(I) thiocyanate adducts with bulky monodentate tertiary phosphine ligands.

A number of adducts of copper(I) thiocyanate with bulky tertiary phosphine ligands, and some nitrogen-base solvates, were synthesized and structurally and spectroscopically characterised. CuSCN:PCy3 (1:2), as crystallized from pyridine, is shown by a single crystal X-ray study to be a one-dimensional polymer ...(Cy3P)2CuSCN(Cy3P)2CuSCN... (1) with the four-coordinate copper atoms linked end-on by S-SCN-N bridging thiocyanate groups. A second form (2), obtained from acetonitrile, was also identified and shown by IR and 31P CPMAS NMR spectroscopy to be mononuclear, with the magnitude of the dν(Cu) parameter measured from the 31P CPMAS and the ν(CN) value from the IR clearly establishing this compound as three-coordinate [(Cy3P)2CuNCS]. Two further CuSCN/PCy3 compounds CuSCN:PCy3 (1:1) (3), and CuSCN:PCy3:py (1:1:1) (4) were also characterized spectroscopically, with the dν(Cu) parameters indicating three- and four-coordinate copper sites, respectively. Attempts to obtain a 1:2 adduct with tri-t-butylphosphine have yielded, from pyridine, the 1:1 adduct as a dimer [(Bu(t)3P)((SCN)(NCS))Cu(PBu(t)3)] (5), while similar attempts with tri-o-tolylphosphine (from acetonitrile and pyridine (= L)) resulted in solvated 1:1:1 CuSCN:P(o-tol)3:L forms as dimeric [{(o-tol)3P}LCu((SCN)(NCS))CuL{P(o-tol)3}] (6 and 8). The solvent-free 1:1 CuSCN:P(o-tol)3 adduct (7), obtained by desolvation of 6, was characterized spectroscopically and dν(Cu) measurements from the 31P CPMAS NMR data are consistent with the decrease in coordination number of the copper atom from four (for 6) (P,N(MeCN)Cu,S,N) to three (for 7) (PCuS,N) upon loss of the acetonitrile of solvation. These results are compared with those previously reported for mononuclear and binuclear PPh3 adducts which demonstrate a clear tendency for the copper centre to remain four-coordinate. The IR spectroscopic measurements on these compounds show that bands in the far-IR spectra provide a much more definitive criterion for distinguishing between bridging and terminal bonding than does an often-used empirical rule based on ν(CN) in the mid-IR, which leads to the wrong conclusion in some cases.

Mechanochemical and solution synthesis, and crystal structures and IR and solid-state (CPMAS) NMR spectroscopy of some bis(triphenylphosphine)silver(I) mono- and di-hydrogencitrate systems.

The complex [(Ph(3)P)(2)Ag(H(2)cit)]·EtOH (1; H(2)cit(-) = dihydrogencitrate = C(6)H(7)O(7)(-)) contains [(Ph(3)P)(2)Ag(H(2)cit)] molecules in which the silver atom is coordinated to two PPh(3) molecules and the two oxygen atoms of one of the 'terminal'/1-carboxylate groups of the dihydrogencitrate group. The molecules form centrosymmetric hydrogen-bonded dimers in the solid. In [{(Ph(3)P)(2)Ag}(2)(Hcit)], (2), unsymmetrical deprotonation of the citrate grouping is found, from the 1- and 3- (i.e. terminal and central) carboxylates: [(Ph(3)P)(2)Ag(O(2)CCH(2)C(OH) (CH(2)COOH)CO(2))Ag(PPh(3))(2)]. The above complexes, as well as [(Ph(3)P)(3)Ag(H(2)cit)] (3) were prepared via conventional solution methods, involving the reaction of trisilver(I) citrate, citric acid and triphenylphosphine, and by a mechanochemical method involving the reaction of silver(I) oxide, citric acid and triphenylphosphine. IR studies of 1-3 show the presence of coordinated carboxylate and free carboxylic acid groups in the mono- and di-hydrogencitrate ligands, and the formation of 2 from 1 shows that dihydrogencitrate deprotonation can occur upon dissolution of 1 in protic solvents. High-field (9.40 T) (31)P CPMAS NMR spectra were recorded and analysed, yielding heteronuclear (1)J((107/109)Ag,(31)P) and homonuclear (2)J((31)P,(31)P) spin-spin coupling constants.

Solution and mechanochemical syntheses, and spectroscopic and structural studies in the silver(I) (bi-)carbonate: triphenylphosphine system.

Syntheses of a number of adducts of silver(I) (bi-)carbonate with triphenylphosphine, both mechanochemically, and from solution, are described, together with their infra-red spectra, (31)P CP MAS NMR and crystal structures. Ag(HCO(3)):PPh(3) (1:4) has been isolated in the ionic form [Ag(PPh(3))(4)](HCO(3))·2EtOH·3H(2)O. Ag(2)CO(3):PPh(3) (1:4) forms a binuclear neutral molecule [(Ph(3)P)(2)Ag(O,µ-O'·CO)Ag(PPh(3))(2)](·2H(2)O), while Ag(HCO(3)):PPh(3) (1:2) has been isolated in both mononuclear and binuclear forms: [(Ph(3)P)(2)Ag(O(2)COH)] and [(Ph(3)P)(2)Ag(µ-O·CO·OH)(2)Ag(PPh(3))(2)] (both unsolvated). A more convenient method for the preparation of the previously reported copper(I) complex [(Ph(3)P)(2)Cu(HCO(3))] is also reported.

Mechanochemical synthesis in copper(II) halide/pyridine systems: single crystal X-ray diffraction and IR spectroscopic studies.

Whereas complexes of divalent metal halides (X = Cl, Br, I) with/from pyridine commonly crystallise as trans-[M(py)(4)X(2)]·2py, M on a site of 222 symmetry in space group Ccca, true for CuCl(2) and CuBr(2) in particular, the copper(II) iodide adduct is of the form [Cu(py)(4)I]I·2py, Cu on a site of mm2 symmetry in space group Cmcm, and five-coordinate (square-pyramidal), the same cationic species also being found in 2[Cu(py)(4)I](I(3))·[(py)(2)Cu(µ-I)(2)Cu(py)(2)] (structurally defined). Bromide or N-thiocyanate may be substituted for the unbound iodide ion in the solvated salt, resulting in complexes which crystallize in space group Ccca, but with both anions and the metal atom disordered. In [Cu(py)(4)(I(3))(2)], a pair of long Cu···I contacts approach a square-planar Cu(py)(4) array. Assignments of the ν(CuN) and ν(CuX) (X = Br, I, SCN) bands in the far-IR spectra are made, the latter with the aid of analogous assignments for [Cu(py)(2)X(2)] (X = Cl, Br), which show a dependence of ν(CuX) on the Cu-X bond length that is very similar to that determined previously for copper(i) halide complexes. The structure of the adventitious complex [(trans-)(H(2)O)(py)(4)CuClCu(py)(4)](I(3))(3)·H(2)O is also recorded, with six- and five-coordinate copper atoms; rational synthesis provides [{Cu(py)(4)}(2)(µ-Cl)](I(3))(3)·H(2)O with one water molecule less. In [{Cu(py)(4)Cl}((∞|∞))](I(3))·3py, square pyramidal [Cu(py)(4)Cl](+) cations, assisted by Cl···Cu interactions, stack to give rise to infinite polymeric strings. Several of these compounds were prepared mechanochemically, illustrating the applicability of this method to syntheses involving redox reactions as well as to complex syntheses involving up to five components. The totality of results demonstrates that the [Cu(II)(py)(4)] entity can be stabilized in an unexpectedly diverse range of mononuclear and multinuclear complexes through the presence of lattice pyridine molecules, the bulky triiodide ion, or a combination of both.

Evaluation of a crystalline nanosuspension: polymorphism, process induced transformation and in vivo studies.

The aim of this work was to evaluate a crystalline nanosuspension of an investigational anticancer compound, SN 30191. Solid forms of SN 30191 were prepared and characterized by thermal analysis, infrared spectroscopy, ¹³C CP/MAS SSNMR spectroscopy, SEM and powder XRD. Wet milling was performed using a high pressure homogenizer and process induced transformations were studied as a function of time and pressure using infrared spectroscopy. Dose-toxicity and pharmacokinetics (PK) of the nanocrystal formulation were evaluated in mice after intravenous administration. SN 30191 was found to exist in two polymorphic forms (I and II) and a hydrate with an equilibrium solubility < 0.1 µg/ml (pH 1.3-11.0, 37 °C). Wet milling resulted in solid state transformation as a function of pressure. Form II was found to transform into form I at intermediate pressures. A further increase in pressure resulted in formation of a hydrate. The final nanosuspension consisted of SN 30191 as a hydrate. The dose-toxicity studies revealed higher tolerance (~4 times) for the nanosuspension (10 mg/kg) when compared with a solution formulation (2.5 mg/kg). Compared with solution formulation, the nanosuspension allowed the delivery of a higher dose and rendered possible the performance of PK and tissue distribution studies in animals.

Novel complexes of silver(I) sulfate with 1-methylimidazole-2-thione: structures and vibrational spectroscopy.

Crystallization of silver(I) sulfate with the ligand 1-methylimidazole-2-thione ('Hmimt') from aqueous solution, instead of yielding the expected 1:6 Ag(2)SO(4):Hmimt complex analogous to numerous other Ag(2)SO(4):thiourea-based ligand (1:6) complexes, has resulted in novel polymeric forms, one of unusual stoichiometry. Ag(2)SO(4):Hmimt (1:4) (x H(2)O) is of the form [...(mu-Hmimt)(2)Ag(mu-Hmimt)(2)Ag...](infinity|infinity)(SO(4)), with a one-dimensional polymeric cation. Ag(2)SO(4):Hmimt (3:8) (x 9 1/2 H(2)O) is a polymeric sheet structure containing Ag(12)(SO(4))(6)(Hmimt)(15) kernels linked by Hmimt ligands. The IR spectra of these compounds show unusually large shifts of the nu(NH) band due to the presence of N-H...O hydrogen bonding involving the N-H group of the ligand and the sulfate oxygen atoms. The complexes were also readily prepared by the solvent-assisted mechanochemical method, and the utility of this method for the preparation of deuterium-exchanged products for assistance in the assignment of the IR spectra is illustrated.

Structural and spectroscopic studies of some adducts of silver(I) halides with thiourea and N-ethyl substituted thioureas.

Syntheses, single crystal X-ray structural and spectroscopic characterizations are described for a variety of adducts of silver halides with thiourea ('tu'), N-ethylthiourea ('ettu' = EtNH.CS.NH(2)) and N,N'-diethylthiourea ('detu' = EtNH.CS.EtNH). This study greatly extends our knowledge of the complex chemistry of silver(i) halides with tu. The unexpected diversity of composition of such complexes was initially revealed by the powerful mechanochemical/IR method and the structures of several of the new complexes were determined by X-ray crystallographic studies of samples subsequently prepared from aqueous solution. Structural characterizations provide extensive geometrical data for (mononuclear 1 : 3) [XAg(xtu)(3)] arrays (xtu = ettu, detu; X = Cl, Br, I), assisting vibrational spectroscopic assignments. With the parent tu ligand, binuclear ionic forms are obtained: [tu(2)Ag(mu-tu)(2)Agtu(2)]X(2), the chloride as the dihydrate and the bromide as a di(thiourea) dihydrate adduct. With tu 1 : 2 complexes are defined for X = Cl, Br, as isomorphous one-dimensional polymers; AgCl:tu (1 : 1) is a two-dimensional net with six-membered Ag(3)S(3) rings and terminal chloride. Intermediate stoichiometries are defined in AgBr:tu (2 : 3), a one-dimensional polymer of Ag(2)S(2) rhombs linked at the silver atoms, while [Cl(2)Ag(3)(tu)(4)](NO(3)).H(2)O is also a one-dimensional polymer in which chloride and thiourea sulfur atoms link six-membered Ag(3)S(3) rings. Diagnostic bands in the IR and far-IR spectra of all of the synthesized complexes are assigned and interpreted in relation to the structures.

Spectroscopy and structures of two complete families, one mononuclear, the other binuclear, of 1 : 2 CuX : dptu stoichiometry (X = Cl, Br, I; 'dptu' = N,N'-diphenylthiourea).

Crystallization of the copper(i) halides (CuX; X = Cl, Br, I) with N,N'-diphenylthiourea ('dptu' = (PhNH)(2)CS) in 1 : 2 ratio from acetonitrile solution in ambient conditions yields a mononuclear isomorphous series of complexes of the form [XCu(dptu)(2)].H(2)O, an unusually complete array, with the central copper atoms in quasi-trigonal planar environments, as shown by single crystal X-ray studies, in turn providing a platform for comparative spectroscopic studies. Under anhydrous conditions, anhydrous compounds may be obtained, a full series again being accessible, but now of the binuclear form [(dptu)XCu(mu-S-dptu)(2)CuX(dptu)], the chloride being a bis(acetonitrile) solvate, the isomorphous bromide and iodide pair being unsolvated. A (solvated) sulfate salt is found to be of the form [Cu(dptu)(2)](2)(SO(4)), providing a novel example of a copper(i) atom being (quasi-)linearly coordinated by the pair of unidentate (dptu) sulfur ligands, Cu-S 2.1770(5), 2.1811(5) A, S-Cu-S 162.18(2) degrees . The nu(CuX) vibrational frequencies are assigned in the far-IR spectra of [XCu(dptu)(2)].H(2)O (X = Cl, Br, I) at 274, 207, and 190 cm(-1) respectively. The broadline static (65)Cu NMR spectra of [Cl(2)Cu(2)(dptu)(4)].2CH(3)CN and [X(2)Cu(2)(dptu)(4)] (X = Br, I) have been recorded at 9.4 and 7.05 T, and the spectra have been analysed to yield the (65)Cu nuclear quadrupole coupling and chemical shift parameters. The (63,65)Cu nuclear quadrupole resonance frequencies of [XCu(dptu)(2)].H(2)O (X = Cl, Br, I) have also been measured, and the resulting (65)Cu quadrupole coupling constants are ca. 4x those of the dimeric [X(2)Cu(2)(dptu)(4)] compounds.

Control of reversible ligand insertion via supramolecular interactions in the solid state.

Reversible insertion of a ligand molecule into the coordination sphere of a metal complex in the solid state by variation of associated supramolecular hydrogen-bonding interactions in the solid is demonstrated in studies of complexes of copper(I) nitrate with thiourea.

Solvent-assisted solid-state synthesis: separating the chemical from the mechanical in mechanochemical synthesis.

High-yielding syntheses involving reactions in the diffusion zone between solid reactants are demonstrated in studies of complex formation between copper(i) thiocyanate and ethylenethiourea.

1 : 1 complexes of silver(I) thiocyanate with (substituted) thiourea ligands.

Syntheses and single crystal X-ray structural characterizations, together with infrared spectroscopic studies, are recorded for 1 : 1 adducts of silver(I) thiocyanate with thiourea ('tu') and N,N'-diethylthiourea ('detu' identical with (EtNH)(2)CS). The two complexes display novel and different polymeric forms. That formed with tu is a double-stranded form, comprising a pair of Ag(mu-S-tu)Ag(mu-... strands linked by pairs of mu-SCN anions, the whole array having quasi-2 symmetry about the polymer axis. The detu adduct takes the ionic form [Ag(detu)2](infinity|infinity)[Ag(SCN)2](infinity|infinity), both cation and anion being one-dimensional polymers lying in parallel, and both of the form ...Ag(mu-S-L)2Ag(mu-... (L = SCN or detu), disposed about crystallographic 4 axes. Redeterminations of the structures of AgSCN : tu, etu (1 : 2) ('etu' = ethylenethiourea, (CH2NH)2CS)) with quasi-trigonal silver atom environments (the etu adduct the more closely so), are also recorded as a basis for an IR spectroscopic characterization of the [(NCS)Ag(S-xtu)2] array. A mechanochemical/infrared study of the AgSCN:etu (1 : 1) system showed that no 1 : 1 complex exists in this case, the product being a mixture of the 1 : 2 complex and a novel 1 : 0.5 complex. The latter complex was prepared both mechanochemically and from solution, and characterized by infrared spectroscopy. Diagnostic ligand and metal-ligand bands in the IR and far-IR spectra are assigned for all of the complexes studied and for AgSCN and are discussed in relation to the structures of the complexes. The double degeneracy of the delta(SCN) mode of the coordinated thiocyanate is lifted and the first overtone of this band at gains intensity in the IR in the 1 : 1 complexes, behaviour that is not observed for the terminal bonding mode that is present in the 1 : 2 complexes.

Structural and infrared spectroscopic studies of some novel mechanochemically accessed adducts of silver(I) oxoanion salts with thiourea.

An investigation of the silver(I) nitrate/thiourea ("tu") system, exploiting the uniquely powerful access provided by the recently developed combination of mechanochemical synthesis coupled with vibrational spectroscopy, has resulted in the identification of solid adducts AgNO3/tu (x:y) for x:y = 1:1, 1:1.5, 15:23 (= 1:1.5333), and 1:3. This contrasts with previously published claims for the existence of 1:2 and 1:4 complexes and was confirmed in the case of the 1:3 and 15:23 complexes by X-ray crystal structure determinations on samples prepared by crystallization from aqueous solution. The 1:3 sulfate and perchlorate complexes were also prepared for comparison with the corresponding nitrate compound. In the 1:3 nitrate complex, the one independent silver atom major component (0.78(1)) is closely trigonal planar AgS3 (Ag-S 2.518(2)-2.592(1) A, Sigma(S-Ag-S) 359.7(0) degrees); there are minor nearby components (0.11(1)) which may be regarded as four-coordinate, forming a putative one-dimensional polymer. The sulfate, obtained as its tetrahydrate, has a cation of the familiar binuclear form [{(tu)2Ag(mu-S-tu)}2](SO4) x 4 H2O, while the perchlorate, previously also characterized with the binuclear cation in the anhydrate, has now been isolated as the hemihydrate, having a single-stranded polymeric cation, [...Ag(tu)2(mu-S-tu)...](infinity|infinity)(ClO4) x 0.5 H2O, similar to that observed in CuX/tu (1:3) (X = Cl, Br, I). The remarkable 15:23 nitrate complex (shown to be distinct from the 1:1.5 complex) may be regarded as essentially ionic [Ag15(tu)23(ONO2)](infinity|infinity)(14+)(NO3(-)-)14 (the cation incorporating one O-nitrate ion loosely associated) and comprising one-dimensional polymer strands made up of four-, six-, and eight-membered Ag(2n)S(2n) rings, cross-linked by the sulfur of one of the tu ligands. The nu(CS) and nu(alpha)(CN) bands in the infrared spectra of the complete series of adducts show a monotonic wavenumber decrease and increase, respectively, with decreasing tu content of the adduct, indicating a decrease in the C-S bond strength and a concomitant increase in the C-N bond strength with increasing Ag-S bond strength. The increase in Ag-S bond strength with decreasing tu content is also indicated by an increase in the wavenumbers of the bands assigned to nu(AgS) in the 140-200 cm(-1) region in the far-IR. These and the structural data for the 1:3 and 15:23 complexes provide the basis for establishing a correlation between nu(AgS) and the Ag-S bond length d(AgS) for silver complexes involving the tu ligand.

Crystal structures and vibrational spectroscopy of copper(I) thiourea complexes.

Several synthetic strategies using copper(I) starting materials or copper(II) compounds and an in situ sulfite reductant have been used to systematically explore the chemistry of copper(I) complexes with thiourea and substituted thiourea ligands. This has resulted in the discovery of several new complexes and methods for the bulk synthesis of some previously reported complexes that had been prepared adventitiously in small quantity. The new complexes are (tu = thiourea, dmtu = N,N'-dimethylthiourea, etu = ethylenethiourea): [I(4)Cu(4)(tu)(6)].H(2)O, [Cu(4)(tu)(10)](NO(3)).tu.3H(2)O, [BrCu(dmtu)(3)], [ICu(dmtu)(3)](2), [BrCu(etu)(2)](2), [ICu(etu)(2)], [ICu(etu)(2)](3). [I(4)Cu(4)(tu)(6)].H(2)O has an adamantanoid structure, with four terminal iodide ligands and six doubly bridging tu ligands. In contrast to this, [Cu(4)(tu)(10)](NO(3)).tu.3H(2)O contains a tetranuclear cluster in which four of the tu ligands are terminal and the other six are doubly bridging. [BrCu(dmtu)(3)] is a mononuclear complex with tetrahedral coordination of copper by one bromide and three dmtu ligands, whereas [Cu(dmtu)(3)](2)I(2) has a centrosymmetric dimeric cation with two uncoordinated iodides, four terminal dmtu and two doubly bridging dmtu ligands, [(dmtu)(2)Cu(mu-S-dmtu)(2)Cu(dmtu)(2)]I(2). A reversal of this monomer to dimer trend from bromide to iodide is seen for the etu counterparts: [BrCu(etu)(2)](2) is a centrosymmetric dimer with two doubly bridging etu ligands, [(etu)BrCu(mu-S-etu)(2)CuBr(etu)], whereas [ICu(etu)(2)] is a trigonal planar monomer, although the novel [I(3)Cu(3)(etu)(6)] is also defined. Infrared and Raman spectra of the synthesized complexes were recorded and the metal-ligand vibrational frequencies have been assigned in many cases. The results confirm previously observed correlations between the vibrational frequencies and the corresponding bond lengths for complexes of the unsubstituted tu ligand. A mechanochemical/infrared method was used to synthesize [I(3)Cu(3)(etu)(6)] from CuI and etu, and to demonstrate the polymorphic transition from [ICu(etu)(2)] to [I(3)Cu(3)(etu)(6)].

The role of short-range diffusion in solvent-assisted mechanochemical synthesis of metal complexes.

The role of short-range diffusion in solvent-assisted mechanochemical synthesis is demonstrated in studies of a polymorphic transition and a ligand dissociation reaction involving copper(I) thiocyanate complexes.

Structural, (197)Au Mössbauer and solid state (31)P CP/MAS NMR studies on bis (cis-bis(diphenylphosphino)ethylene) gold(I) complexes [Au(dppey)(2)]X for X = PF(6), I.

(197)Au Mössbauer spectra for the d(10) gold(i) phosphine complexes, [Au(dppey)(2)]X (X = PF(6), I; dppey = (cis-bis(diphenylphosphino)ethylene), and the single crystal X-ray structure and solid state (31)P CPMAS NMR spectrum of [Au(dppey)(2)]I are reported here. In [Au(dppey)(2)]I the AuP(4) coordination geometry is distorted from the approximately D(2) symmetry observed for the PF(6)(-) complex with Au-P bond lengths 2.380(2)-2.426(2) A and inter-ligand P-Au-P angles 110.63(5)-137.71(8) degrees . Quadrupole splitting parameters derived from the Mössbauer spectra are consistent with the increased distortion of the AuP(4) coordination sphere with values of 1.22 and 1.46 mm s(-1) for the PF(6)(-) and I(-) complexes respectively. In the solid state (31)P CP MAS NMR spectrum of [Au(dppey)(2)]I, signals for each of the four crystallographically independent phosphorus nuclei are observed, with the magnitude of the (197)Au quadrupole coupling being sufficiently large to produce a collapse of (1)J(Au-P) splitting from quartets to doublets. The results highlight the important role played by the counter anion in the determination of the structural and spectroscopic properties of these sterically crowded d(10) complexes.