Molecular rectangles from platinum(II) and bridging dicarbene, diisocyanide and 4,4'-bipyridine ligands.

A series of benzobisimidazolium salts have been prepared and treated with [PtCl2(dppe)] or [PtCl2(dmpe)] in the presence of sodium acetate to yield dinuclear dicarbene-bridged complexes of the type [(P^P)(X)Pt(benzodicarbene)Pt(X)(P^P)](X)2 [5]Br2-[11]I2. The reaction of compounds [7]Br2 and [11]I2 with AgPF6 in acetonitrile led to the exchange of the metal-bound bromo or iodo ligands for acetonitrile and the formation of complexes [(dmpe)(MeCN)Pt(benzodicarbene)Pt(MeCN)(dmpe)](PF6)4 [12](PF6)4 and [13](PF6)4. The dinuclear complex [13](PF6)4 reacts with 4,4'-bipyridine (4,4'-bipy) to give the molecular rectangle [15](PF6)8 featuring two bridging dicarbene and two bridging 4,4'-bipy ligands. Complex [13](PF6)4 also reacts with ß,ß'-bis(triisopropylsiloxy)phenyl-1,4-diisocyanide 16 followed by hydrolysis of the Si-O bonds and intramolecular carbene formation to yield the molecular square [18](BF4)8 featuring bridging NR,NR- and NH,O-substituted dicarbene ligands. Reaction of the dinuclear complex [12](PF6)4 containing a sterically demanding N,N',N'',N'''-substituted dicarbene ligand under otherwise identical reaction conditions did not lead to any molecular rectangles. The molecular square [19](BF4)8 was synthesized from ß,ß'-bis(triisopropylsiloxy)phenyl-1,4-diisocyanide 16 and [PtCl2(dmpe)] in the presence of AgBF4. It reacts to yield the molecular square [20](BF4)8 with four NH,O-substituted dicarbene ligands by Si-O bond cleavage and subsequent intramolecular cyclization.

Synthesis of polynuclear Ag(I) and Au(I) complexes from macrocyclic tetraimidazolium salts.

The synthesis of the macrocyclic tetraimidazolium salt (H4-1)(Br)4 and the anion exchange to (H4-1)(PF6)4 have been explored. Deprotonation of (H4-1)(PF6)4 with Ag2O yields the mono- and dinuclear silver(I) complexes [Ag(H2-1)](PF6)3 and [Ag2(1)](PF6)2. Transmetallation of the dicarbene and tetracarbene ligands to gold(I) yields the mono- and dinuclear gold(I) complexes [Au(H2-1)](PF6)3 and [Au2(1)](PF6)2. The monosilver complex [Ag(H2-1)](PF6)3, featuring two imidazolium moieties, has been deprotonated and used for the synthesis of the tetranuclear silver(I) octacarbene complex [{Ag(1)}2Ag2](PF6)4.

A planar chiral [2.2]paracyclophane derived N-heterocyclic stannylene.

The reaction of pseudo-ortho-4,12-N,N'-diphenyldiamino-[2.2]paracyclophane ((±)-3) with Sn[N(SiMe(3))(2)](2) results in the formation of the monomeric planar chiral N-heterocyclic stannylene (±)-4, featuring a unique [2.2]paracyclophane backbone, which has been characterized by an X-ray diffraction study.

Synthesis of complexes bearing NH,NMe-substituted NHCs by oxidative addition of 2-halogenato-N-methylbenzimidazoles to Ni(0).

Reaction of 2-X-N-methylbenzimidazole (X = chloro, iodo) with Ni(0) complexes in the presence of dppe or PEt(3) and an external proton source yielded via an oxidative addition reaction nickel(II) complexes bearing NH,NMe-functionalized NHC ligands.

Stepwise formation of a molecular square with bridging NH,O-substituted dicarbene building blocks.

The ß,ß'-bis(triisopropylsiloxy)phenyl-1,4-diisocyanide 3 and [Ir(Cp*)Cl(2)](2) were used for the stepwise assembly of the [Ir(Cp*)Cl] cornered molecular square [6](Cl)(4). Synthesis of the tetrakis(diisocyanide) bridged molecular square [Ir(Cp*)Cl(3)](4)(BF(4))(4) [5](BF(4))(4) followed by cleavage of the O-Si(i-Pr)(3) bonds of the diisocyanide bridges with HCl/i-PrOH led to an intramolecular attack of the liberated hydroxyl groups at the isocyanide carbon atoms with formation of molecular square [6](Cl)(4) featuring four dicarbene linkers.

Palladium and platinum complexes of a benzannulated N-heterocyclic plumbylene with an unusual bonding mode.

Reaction of the N,N'-diisobutyl-substituted benzannulated N-heterocyclic plumbylene (NHPb) 1 with [Pd(PPh(3))(4)] and [Pt(PPh(3))(4)] gave the complexes [M(NHPb)(PPh(3))(3)] (M = Pd [2], Pt [3]). X-ray diffraction studies of both complexes showed an angle of ~125° between the plumbylene plane and the transition-metal-Pb axis, indicating coordination of the transition metal to the empty π orbital of the plumbylene Pb atom. The experimentally determined metric parameters of complexes [2] and [3] are discussed on the basis of DFT calculations.

Synthesis of NHC complexes by oxidative addition of 2-chloro-N-methylbenzimidazole.

The oxidative addition of 2-chloro-N-methylbenzimdazole to complexes of type [M(PPh(3))(4)] yields after N-protonation compounds with NH,NMe-substituted NHC ligands. For M = Pd complex compound trans-[3]BF(4) was obtained, while the oxidative addition for M = Pt yielded a mixture of cis-[4]BF(4) (major) and trans-[4]BF(4) (minor).

Organozinc hydroxylamides: on the bulk-dependent interplay of nuclearity, structure and dynamics.

The reactions of zinc dialkyls, R(2)Zn (1a-d; R = Me (a), Et (b), iPr (c) and tBu (d)), with N,N-dialkylhydroxylamines, HO-NR'(2) (2a-c; R' = Me (a), Et (b) and iPr (c)), afford organozinc hydroxylamides under alkane extrusion. Species of different nuclearity are observed, depending on the hydroxylamine 2 employed. The smaller 2a and 2b give pentanuclear complexes of the general formula Zn(RZn)(4)O-NR'(2))(6) (R = Me, Et, iPr and tBu; R' = Me and Et), whereas the derivatives of 2c are tetramers of the general formula (RZn)(4)(O-NR'(2))(4) (R = Me, Et and iPr; R' = iPr) as governed by bulk issues about the N-donor. Due to the ability of the double-donor unit O-NR(2) to change its bridging mode, two coordination isomers exist for both types of compounds. The pentanuclear species crystallise either in a heterofenestrane or an octahedroid motif. For these species, the central Zn atom exhibits either coordination number 4 or 6; in solution, a rapid change between coordination isomers is observed. Due to the absence of a central Zn atom in the tetranuclear species, these aggregate in heterocubane geometries or such derived thereof. They display the O-N units in either κ(3)O or κ(2)O;κ(1)N mode. The tetranuclear species are also yielded with the less sterically encumbered precursors under thermodynamic conditions (i.e. reflux), as exemplified by the reaction of Me(2)Zn (1a) with HO-NEt(2) (2b). They are non-dynamic in solution, showing that a central cation is mandatory for the fluxional behaviour observed for the pentanuclear derivatives. DFT studies on the O-NMe(2) series reveal that the relative energies of the pentazinc isomers become more similar with increasing RZn group size; possible conversions of these to their tetrazinc counterparts were also scrutinised. Two κ(3)O-bridged degradation products of hydroxylamide complexes could be structurally characterised. They were formed either by partial product hydrolysis, or by in situ oxygenation of the starting zinc dialkyl.

Polynuclear and mixed-ligand mononuclear Cu(I) complexes with N-thiophosphorylated thioureas and 1,10-phenanthroline or PPh3.

Deprotonation of the N-thiophosphorylated thioureas RC(S)NHP(S)(OiPr)(2) (R = Me(2)N, HL(I); iPrNH, HL(II); 2,6-Me(2)C(6)H(3)NH, HL(III), 2,4,6-Me(3)C(6)H(2)NH, HL(IV), aza-15-crown-5, HL(V)) and reaction with CuI or Cu(NO(3))(2) in aqueous EtOH leads to the polynuclear complexes [Cu(4)(L(I)-S,S')(4)], [Cu(8)(L(II)-S,S')(8)], and [Cu(3)(L(III-V)-S,S')(3)]. The structures of these compounds were investigated by IR, (1)H, (31)P{(1)H} NMR, UV-vis spectroscopy and elemental analyses. The crystal structures of [Cu(4)L(I)(4)], [Cu(8)L(II)(8)], [Cu(3)L(III,IV)(3)] were determined by single-crystal X-ray diffraction. Reaction of the deprotonated ligands (L(I-V))(-) with a mixture of CuI and 1,10-phenanthroline (phen) or PPh(3) leads to the mixed-ligand mononuclear complexes [Cu(phen)L(I-V)], [Cu(PPh(3))L(I-V)] or [Cu(PPh(3))(2)L(I-V)]. The same mixed-ligand complexes were obtained from the reaction of [Cu(4)L(I)(4)], [Cu(8)L(II)(8)], [Cu(3)L(III-V)(3)] with phen or PPh(3).

Sterically demanding and chiral N,N'-disubstituted N-heterocyclic germylenes and stannylenes.

The N,N'-dimesitylene substituted o-phenylenediamine 1 reacts with Sn[N(SiMe(3))(2)](2) under formation of the monomeric N-heterocyclic stannylene 2, while the chiral N,N'-substituted o-phenylenediamine 3 reacts with E[N(SiMe(3))(2)](2) (E = Ge, Sn) under formation of the chiral germylene 4 and the chiral stannylene 5, respectively. X-Ray diffraction studies with both stannylenes demonstrated that the metal centers in these compounds are sufficiently sterically protected to prevent interaction between the tin center and the nitrogen donors of adjacent molecules.

Copper(I) complexes with N-(diisopropoxythiophosphoryl)thiobenzamide PhC(S)NHP(S)(OiPr)2.

Reaction of the potassium salt of N-thiophosphorylthiobenzamide PhC(S)NHP(S)(OiPr)(2) (HL) with CuI in aqueous EtOH leads to the tetranuclear [Cu(4)L(4)] and the polynuclear [KCuL(2)](n) complexes, while the same reactions using the lithium or sodium salts of HL exclusively lead to the tetramer [Cu(4)L(4)]. Reaction of KL with the mixture of CuI and 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen) leads to the mononuclear complexes [Cu(bpy)L] and [Cu(phen)L]. The same complexes were obtained by the reaction of [Cu(4)L(4)] with bpy or phen.

Self-assembly of molecular cylinders from polycarbene ligands and Ag(I) or Au(I).

Tris- and tetrakis(imidazolium) salts react with Ag(2)O to give cylindrical polynuclear silver(I) complexes such as the tetrasilver derivative [Ag(4)(1)(2)](PF(6))(4). The silver(I) complexes undergo transmetalation with [AuCl(SMe(2))] to yield homonuclear gold(I) complexes with retention of the metallosupramolecular assembly.

Template-controlled synthesis of a planar [16]ane-P2C(NHC)2 macrocycle.

Reaction of tetraphosphine platinum(II) complexes with 2-azidoethyl isocyanide 3 in methanol leads to complexes with two trans-coordinated NH,NH-stabilized carbene ligands 6(X)(2). Complexes 6(X)(2) react with phenyldivinylphosphine under substitution of the remaining phosphine ligands followed by an intramolecular hydroamination reaction to produce complex 1(PF(6))(2) with a macrocyclic [16]ane-P(2)C(NHC)(2) ligand.

Coordination chemistry of the sulfur analog of tricatechol siderophores.

Reaction of the siderophore analog tris(benzene-o-dithiol) ligand H6-1 with Ti(OPr)4 in methanol leads to the formation of the siderophore analog complex (Ph4As)2[Ti(1)3] exhibiting exclusively thiolato coordination to the metal center.

Syntheses and structures of (N',N'-dimethylhydrazido)silanes.

The hydrazidosilanes Ph(2)Si(NHNMe(2))(2) (1), Me(2)Si(NHNMe(2))(2) (2), PhSi(NHNMe(2))(3) (3), MeSi(NHNMe(2))(3) (4), PhClSi(NHNMe(2))(2) (5), MeClSi(NHNMe(2))(2) (6), Me(2)ClSi(NHNMe(2)) (7), MeClHSi(NHNMe(2)) (8), MeHSi(NHNMe(2))(2) (9), Me(2)HSi(NHNMe(2)) (10), Me(2)NN[HSi(NHNMe(2))(2)](2) (11) and Si(NHNMe(2))(4) (12) have been prepared by the reaction of the corresponding chlorosilanes with N,N-dimethylhydrazine. Some of the compounds containing Si-Cl and N-H functions simultaneously (6,7,8 ) are very reactive and tend to polymerise and could only be characterised by spectroscopic methods ((1)H, (13)C, (29)Si NMR, IR, MS). All other compounds could additionally be characterised by elemental analyses. The structures of , , , , and in the solid state were determined by X-ray diffraction. These include the first structural determinations of compounds containing SiH-NH-N (9,11) and SiCl-NH-N (5) units.

Metal template controlled formation of [11]ane-P2C(NHC) macrocycles.

The synthesis of N-heterocyclic carbene-diphosphine macrocycles by metal template assisted cyclization reactions has been explored. Attempts to prepare the facial tungsten tricarbonyl precursor complex containing an NH,NH-functionalized carbene and a suitable diphosphine resulted in displacement of the coordinated carbene and the isolation of the corresponding diphosphine tungsten tetracarbonyl [3]. The Re(I) chloro tetracarbonyl complex bearing an NH,NH-functionalized carbene ligand [5] can be prepared and is a suitable precursor for the subsequent formation of the carbene-diphosphine tricarbonyl intermediate [H(2)-6]Cl bearing reactive 2-fluoro substituents at the phosphine-phenyl groups. Two of these fluoro substituents are displaced by a nucleophilic attack upon deprotonation of the coordinated NH,NH-functionalized carbene resulting in new C-N bonds resulting in the partially coupled intermediate, [10], followed by the desired complex with the macrocyclic ligand [8]Cl. Compounds [H-7]Cl and [8]Cl are also formed during the synthesis of [H(2)-6]Cl as a result of spontaneous HF elimination. Complex [8](+) may be converted to the neutral dicarbonyl chloro analog [11] by action of Me(3)NO. Related chemistry with analogous manganese complexes is observed. Thus, from the NH,NH-functionalized carbene manganese bromo tetracarbonyl [12], the diphosphine manganese carbene tricarbonyl cation [H(2)-13] may be readily prepared which provides the macrocyclic carbene-diphosphine tricarbonyl cation [14](+) following base promoted nucleophilic intramolecular displacement of fluoride. Again, [14](+) is converted to the neutral bromo dicarbonyl upon reaction with Me(3)NO. All complexes with the exception of the reaction intermediate [10] have been characterized by spectroscopic and analytical methods in addition to X-ray crystallographic structure determinations for complexes [3], [5], [H(2)-6]Cl, [H(2)-6][9], [8]Cl, [10], [11], [12], and [14]Br.

Bis(hydroxylaminato)-mono(pentamethylcyclopentadienyl) rare-earth metal complexes.

Salt metathesis reactions involving the anhydrous rare-earth metal trichlorides MCl(3) (M = Y, Ho, Er and Lu) and the N,N-diethylhydroxylaminato potassium salt, KONEt(2) (1), and KC(5)Me(5) result in formation of rare-earth metal hydroxylaminato complexes of the type [(C(5)Me(5))M(mu-eta(1):eta(2)-ONEt(2))(eta(2)-ONEt(2))](2) (M = Y (2a), Ho (2b), Er (2c) and Lu (2d)). Compound 1 was characterised by elemental analysis, compounds 2a and 2d by NMR spectroscopy and compounds 2a-d by elemental analyses, mass-spectrometry and single crystal X-ray diffraction. Compounds 2a-d are isostructural in the solid state. Effective saturation of the coordination sphere of the rare-earth metal atoms by the hydroxylaminato groups is achieved by the formation of three-membered MON rings.

Supramolecular structures from mono and dimetalated biscarbene ligands.

A series of benzobisimidazolium salts 1a-d has been prepared by tetraalkylation of benzobisimidazol. The salts 1a-d react with two equivalents of [Pt(Cl)2dppe] in the presence of 2.2 equivalents of sodium acetate to yield the dinuclear biscarbene complexes 2a-d. Under the same reaction conditions, the benzobisimidazolium salts react with only one equivalent of [Pt(Cl)2dppe] and one equivalent of sodium acetate to yield the monometalated carbene/benzimidazolium derivatives 3a,3c. Benzobisimidazolium salt 1c reacts with two equivalents of nickelocene to give the biscarbene bridged dinuclear nickel complex 4. Treatment of 4 with two equivalents of 4,4-bipyridine leads to the formation of the CpNiII-cornered molecular rectangle 5.