Synthesis,characterization, and solution redox properties of (trimpsi)M(CO)(2)(NO) complexes [M = V,Nb, Ta; trimpsi = (t)BuSi(CH(2)PMe(2))(3)

Treatment of [Et(4)N][M(CO)(6)] (M = Nb, Ta) with I(2) in DME at -78 degrees C produces solutions of the bimetallic anions [M(2micro-I)(3)(CO)(8)](-). Addition of the tripodal phosphine (t)BuSi(CH(2)PMe(2))(3) (trimpsi) followed by refluxing affords (trimpsi)M(CO)(3)I [M = Nb (1), Ta (2)], which are isolable in good yields as air-stable, orange-red microcrystalline solids. Reduction of these complexes with 2 equiv of Na/Hg, followed by treatment with Diazald in THF, results in the formation of (trimpsi)M(CO)(2)(NO) [M = Nb (3), Ta (4)] in high isolated yields. The congeneric vanadium complex, (trimpsi)V(CO)(2)(NO) (5), can be prepared by reacting [Et(4)N][V(CO)(6)] with [NO][BF(4)] in CH(2)Cl(2) to form V(CO)(5)(NO). These solutions are treated with 1 equiv of trimpsi to obtain (eta(2)-trimpsi)V(CO)(3)(NO). Refluxing orange THF solutions of this material affords 5 in moderate yields. Reaction of (trimpsi)VCl(3)(THF) (6) with 4 equiv of sodium naphthalenide in THF in the presence of excess CO provides [Et(4)N][(trimpsi)V(CO)(3)] (7), (trimpsi)V(CO)(3)H, and [(trimpsi)V(micro-Cl)(3)V(trimpsi)][(eta(2)-trimpsi)V(CO)(4)].3THF ([8][9].3THF). All new complexes have been characterized by conventional spectroscopic methods, and the solid-state molecular structures of 2.(1)/(2)THF, 3-5, and [8][9].3THF have been established by X-ray diffraction analyses. The solution redox properties of 3-5 have also been investigated by cyclic voltammetry. Cyclic voltammograms of 3 and 4 both exhibit an irreversible oxidation feature in CH(2)Cl(2) (E(p,a) = -0.71 V at 0.5 V/s for 3, while E(p,a) = -0.55 V at 0.5 V/s for 4), while cyclic voltammograms of 5 in CH(2)Cl(2) show a reversible oxidation feature (E(1/2) = -0.74 V) followed by an irreversible feature (0.61 V at 0.5 V/s). The reversible feature corresponds to the formation of the 17e cation [(trimpsi)V(CO)(2)(NO)](+) ([5](+)()), and the irreversible feature likely involves the oxidation of [5](+)() to an unstable 16e dication. Treatment of 5 with [Cp(2)Fe][BF(4)] in CH(2)Cl(2) generates [5][BF(4)], which slowly decomposes once formed. Nevertheless, [5][BF(4)] has been characterized by IR and ESR spectroscopies.     

Differing reactivities of (trimpsi)M(CO)(2)(NO) complexes [M = V,Nb, Ta; trimpsi = (t)BuSi(CH(2)PMe(2))(3)] with halogens and halogen sources

Treatment of (trimpsi)V(CO)(2)(NO) (trimpsi = (t)BuSi(CH(2)PMe(2))(3)) with 1 equiv of PhICl(2) or C(2)Cl(6) or 2 equiv of AgCl affords (trimpsi)V(NO)Cl(2) (1) in moderate yields. Likewise, (trimpsi)V(NO)Br(2) (2) and (trimpsi)V(NO)I(2) (3) are formed by the reactions of (trimpsi)V(CO)(2)(NO) with Br(2) and I(2), respectively. The complexes (trimpsi)M(NO)I(2)(PMe(3)) (M = Nb, 4; Ta, 5) can be isolated in moderate to low yields when the (trimpsi)M(CO)(2)(NO) compounds are sequentially treated with 1 equiv of I(2) and excess PMe(3). The reaction of (trimpsi)V(CO)(2)(NO) with 2 equiv of ClNO forms 1 in low yield, but the reactions of (trimpsi)M(CO)(2)(NO) (M = Nb, Ta) with 1 equiv of ClNO generate (trimpsi)M(NO)(2)Cl (M = Nb, 6; Ta, 7). Complexes 6 and 7 are thermally unstable and decompose quickly at room temperature; consequently, they have been characterized solely by IR and (31)P[(1)H] NMR spectroscopies. All other new complexes have been fully characterized by standard methods, and the solid-state molecular structures of 1.3CH(2)Cl(2), 4.(3/4)CH(2)Cl(2), and 5.THF have been established by single-crystal X-ray diffraction analyses. A convenient method of generating Cl(15)NO has also been developed during the course of these investigations.     

Magnetochemical Properties and Reactions of Vanadium(III) Thiolate Complexes: Preparation of (NEt(4))(3)[V(3)Cl(6)(edt)(3)] and Mixed-Valence (NEt(4))[V(2)(edt)(4)] (edt = Ethane-1,2-dithiolate)

Reactions of the previously reported dinuclear vanadium(III) thiolate anion [V(2)(edt)(4)](2)(-) (edtH(2) = ethane-1,2-dithiol) are described. Treatment of (NEt(4))(2)[V(2)(edt)(4)] (1) in MeCN with equimolar (C(12)H(8)S(2))BF(4) (C(12)H(8)S(2)(+) = the thianthrenium radical cation) results in a one-electron oxidation and isolation of the V(III),V(IV) complex (NEt(4))[V(2)(edt)(4)] (2). The same product can also be obtained by controlled-potential electrolysis of 1 at -0.20 V vs Ag/AgCl. Treatment of 1 in CH(2)Cl(2) with py gives no reaction, but addition of Me(3)SiCl leads to formation of the known V(2)OCl(4)(py)(6) (3). The latter is also formed by the reduction of a 1:1 mixture of VOCl(3) and VCl(3)(THF)(3) in CH(2)Cl(2)/py and by the reaction in CH(2)Cl(2) of VCl(3)(THF)(3) and py with edt(2)(-). Treatment of 1 in MeCN with bpy (2,2'-bipyridine) gives no reaction, but addition of Me(3)SiCl results in formation and isolation of [V(2)OCl(2)(bpy)(4)]Cl(2) (4) identified by spectroscopic comparison with literature data. The reaction of 1 in MeCN with equimolar VCl(3)(THF)(3) and NEt(4)Cl gives (NEt(4))(3)[V(3)Cl(6)(edt)(3)] (5). A more convenient procedure to 5 is the reaction in MeCN of VCl(3)(THF)(3), Na(2)edt, and NEt(4)Cl in a 1:1:1 molar ratio. Complex 5.MeCN crystallizes in triclinic space group P&onemacr; with (at -154 degrees C) a = 14.918(3) ?, b = 17.142(5) ?, c = 11.276(3) ?, alpha = 106.78(1) degrees, beta = 95.03(1) degrees, gamma = 106.18(1) degrees, and Z = 2. The anion contains a near-linear V(3) unit with a face-sharing trioctahedral structure: the three edt(2)(-) groups provide the six bridging S atoms; two edt(2)(-) groups are in a &mgr;-eta(2):eta(2) mode (as in 1), but the third is in a &mgr;(3)-eta(1):eta(2):eta(1) mode. The V.V separations (>3.1 ?) preclude V-V bonding. Variable-temperature solid-state magnetic susceptibility studies have been performed on complexes 1, 2, and 5 in a 1.0 kG field and 5.00-300 K temperature range. For 1, the effective magnetic moment (&mgr;(eff)) gradually decreases from 1.09 &mgr;(B) at 300 K to 0.26 &mgr;(B) at 5.00 K. The data were fit to the Bleaney-Bowers equation, and the fitting parameters were J = -419(11) cm(-)(1) and g = 2.05. The singlet-triplet gap is thus 838 cm(-)(1). For 2, &mgr;(eff) is essentially temperature-independent, slowly decreasing from 1.90 &mgr;(B) at 300 K to 1.86 &mgr;(B) at 55 K and then to 1.63 &mgr;(B) at 5.00 K. The complex thus is S = (1)/(2) with no thermally accessible S = (3)/(2) state. The combined data on 1 and 2, together with the results of EHT calculations, show that 1 and 2 contain a V-V single bond tying up two of the d electrons and that the remaining two d electrons in 1 are antiferromagnetically coupled to give an S = 0 ground state and S = 1 excited state; for 2, the one remaining d electron gives an S = (1)/(2) state. For 5, &mgr;(eff) increases from 5.17 &mgr;(B) at 320 K to a maximum of 6.14 &mgr;(B) at 30.0 K and then decreases slightly to 6.08 &mgr;(B) at 5.00 K. The data were fit to the appropriate theoretical expression to give J = +42.5(6) cm(-)(1), J' = -1.8(5) cm(-)(1), and g = 1.77, where J and J' gauge the interactions between adjacent and terminal V(III) atoms, respectively. The complex has an S = 3 ground state and represents a very rare example of ferromagnetic coupling between V(III) centers.     

Ruthenium complexes with tetraphenylimidodiphosphinate: syntheses, structures, and applications to catalytic organic oxidation

Treatment of Ru(PPh3)3Cl2 with K(tpip) (tpip(-)=[N(Ph2PO)2](-)) afforded Ru(tpip)(PPh3)2Cl (1), which reacted with 4- t-Bu-C6H4CN, SO2(g), and NH 3(g) to give Ru(tpip)(PPh3)2Cl(4- t-BuC6H4CN) (2), Ru(tpip)(PPh3)2Cl(SO2) (3), and fac-[Ru(NH3)3(PPh3)2Cl][tpip] (4), respectively. Reaction of [Ru(CO)2Cl2] x with K(tpip) in refluxing tetrahydrofuran (THF) led to isolation of the K/Ru bimetallic compound K 2Ru2(tpip)4(CO)4Cl2 (5). Photolysis of cis-Ru(tpip) 2(NO)Cl in MeCN and wet CH 2Cl 2 afforded cis-Ru(tpip) 2(MeCN)Cl ( 6) and cis-Ru(tpip)2(H2O)Cl (7), respectively. Refluxing 6 in neat THF yielded Ru(tpip) 2(THF)Cl (8). Treatment of Ru(CHR)Cl2(PCy3)2 (Cy=cyclohexyl) with [Ag(tpip)] 4 afforded cis-Ru(tpip)2(CHR)(PCy3) [R=Ph (9), OEt (10)]. Complex 9 is capable of catalyzing oxidation of alcohols and olefins with N-methylmorpholine N-oxide and iodosylbenzene, respectively. The crystal structures of 2-7 and 9 were determined.     

Synthesis and crystal structure of unprecedented phosphine adducts of d(1)-aryl imido-vanadium(IV) complexes

The reaction of the imido precursor [V(NAr)Cl(2)](n)() (1) (Ar = 2,6-i-Pr(2)C(6)H(3)) with 3 equiv of PMe(2)Ph yields the monomeric complex [V(=NAr)Cl(2)(PMe(2)Ph)(2)] (2). Reacting 1 with 1.5 equiv of dmpe or 1 equiv of dppm affords the dimeric complexes [V(=NAr)Cl(2)(dmpe)](2)(mu-P,P'-dmpe) (3) and [V(=NAr)Cl(2)(dppm)](2) (4), respectively. Complexes 2-4 have been fully characterized by spectroscopic methods, magnetism studies, and X-ray crystallography.     

Formation,preservation, and cleavage of the disulfide bond by vanadium

Reaction of the disulfide [HpicanS](2) (HpicanS is the carboxamide based on picolinate (pic) and o-mercaptoaniline (anS); the [] brackets are used to denote disulfides) with [VOCl(2)(thf)(2)] leads to reductive scission of the disulfide bond and formation of the mixed-valence (V(IV)/V(V)) complex anion [(OVpicanS)(2)mu-O](-) (1), with the dianionic ligand coordinating through the pyridine-N atom, the deprotonated amide-N atom, and thiophenolate-S atom. Reductive cleavage of the SbondS bond is also observed as [VCl(2)(tmeda)(2)] (tmeda=tetramethylethylenediamine) is treated with the disulfides [HsalanS](2) or [HvananS](2) (HsalanS and HvananS are the Schiff bases formed between o-mercaptoaniline and salicylaldehyde (Hsal) or vanillin (Hvan), respectively), yielding the V(III) complexes [VCl(tmeda)(salanS)] (2 a), or [VCl(tmeda)(vananS)] (2 b). The disulfide bond remains intact in the aerial reaction between [HsalanS](2) and [VCl(3)(thf)(3)] to yield the V(V) complex [VOCl[salanS](2)] (3), where (salanS)(2-) coordinates through the two phenolate and one of the imine functions. The S-S bond is also preserved as [VO(van)(2)] or [VO(nap)(2)] (Hnap=2-hydroxynaphthalene-1-carbaldehyde) is treated with bis(2-aminophenyl)disulfide, [anS](2), a reaction which is accompanied by condensation of the aldehyde and the diamine, and complexation of the resulting bis(Schiff bases) [HvananS](2) or [HnapanS](2) to form the complexes [VO[vananS](2)] (4 a) or [VO[napanS](2)] (4 b). In 4 a and 4 b, the phenolate and imine functions, and presumably also one of the disulfide-S atoms, coordinate to V(IV). 2-Mercaptophenyl-2'-pyridinecarboxamide (H(2)picanS) retains its identity in the presence of V(III); reaction between [VCl(3)(thf)(3)] and H(2)picanS yields [V[picanS](2)](-) (5). The dithiophenolate 2,6-bis(mercaptophenylthio)dimethylpyridine (6 a) is oxidized, mediated by VO(2+), to the bis(disulfide) octathiadiaza-cyclo-hexaeicosane 6 b. The relevance of these reactions for the speciation of vanadium under physiological conditions is addressed. [HNEt(3)]-1.0.5 NEt(3,) 3.3 CH(2)Cl(2), [HsalanS](2), [HNEt(3)]-5, and 6 b.4 THF have been characterized by X-ray diffraction analysis.     

Investigations on the interaction of dichloroaluminum carboxylates with Lewis bases and water: an efficient road toward oxo- and hydroxoaluminum carboxylate complexes

A series of dichloroaluminum carboxylates [Cl(2)Al(O(2)CR)](2) (were R = Ph (1a), (t)Bu (1b), CHCH(2) (1c) and C(11)H(23) (1d)) were prepared and extended investigations on their structure and reactivity toward various Lewis bases and H(2)O performed. Compounds [Cl(2)Al(O(2)CR)](2) and their adducts with Lewis bases show a large structural variety, featuring both molecular and ionic forms with different coordination numbers of the metal center and various coordination modes of the carboxylate ligand. Upon addition of a Lewis base of moderate strength the molecular form [Cl(2)Al(O(2)CR)](2) equilibrates with new ionic forms. In the presences of 4-methylpyridine the six-coordinate Lewis acid-base adducts [Cl(2)Al(λ(2)-O(2)CR)(py-Me)(2)] [R = Ph (3a), (t)Bu (3b)] with a chelating carboxylate ligand were formed. The reactions of 1a, 1b, and 1d with 0.33 equiv of H(2)O in THF-toluene solution lead to oxo carboxylates [(Al(3)O)(O(2)CR)(6)(THF)(3)] [AlCl(4)] [where R = Ph (4a(THF)), (t)Bu (4b(THF)), and C(11)H(23) (4d(THF))] in high yield. The similar reaction of 1c in tetrahydrofuran (THF) afforded the chloro(hydroxo)aluminum acrylate [(ClAl)(2)(OH)(O(2)CC(2)H(3))(2) (THF)(4)][AlCl(4)] (5), while the hydrolysis of 1b in MeCN lead to the hydroxoaluminum carboxylate [Al(2)(OH)(O(2)C(t)Bu)(2)(MeCN)(6)][AlCl(4))(3)] (6). All compounds were characterized by elemental analysis, (1)H, (27)Al NMR, and IR spectroscopy, and the molecular structure of 1a, 3a, 3b, 4a(THF), 4b(THF), 4b(py-Me'), 5, and 6 were determined by single-crystal X-ray diffraction. The study provides a platform for testing transformations of secondary building units in Al-Metal-Organic Frameworks toward H(2)O and neutral donor ligands.     

Synthesis, structures and reactivity of ruthenium nitrosyl complexes containing Kläui's oxygen tripodal ligand

Ruthenium nitrosyl complexes containing the Kl?ui's oxgyen tripodal ligand L(OEt)(-) ([CpCo{P(O)(OEt)(2)}(3)](-) where Cp = η(5)-C(5)H(5)) were synthesized and their photolysis studied. The treatment of [Ru(N^N)(NO)Cl(3)] with [AgL(OEt)] and Ag(OTf) afforded [L(OEt)Ru(N^N)(NO)][OTf](2) where N^N = 4,4'-di-tert-butyl-2,2'-bipyridyl (dtbpy) (2·[OTf](2)), 2,2'-bipyridyl (bpy) (3·[OTf](2)), N,N,N'N'-tetramethylethylenediamine (4·[OTf](2)). Anion metathesis of 3·[OTf](2) with HPF(6) and HBF(4) gave 3·[PF(6)](2) and 3·[BF(4)](2), respectively. Similarly, the PF(6)(-) salt 4·[PF(6)](2) was prepared by the reaction of 4·[OTf](2) with HPF(6). The irradiation of [L(OEt)Ru(NO)Cl(2)] (1) with UV light in CH(2)Cl(2)-MeCN and tetrahydrofuran (thf)-H(2)O afforded [L(OEt)RuCl(2)(MeCN)] (5) and the chloro-bridged dimer [L(OEt)RuCl](2)(μ-Cl)(2) (6), respectively. The photolysis of complex [2][OTf](2) in MeCN gave [L(OEt)Ru(dtbpy)(MeCN)][OTf](2) (7). Refluxing complex 5 with RNH(2) in thf gave [L(OEt)RuCl(2)(NH(2)R)] (R = tBu (8), p-tol (9), Ph (10)). The oxidation of complex 6 with PhICl(2) gave [L(OEt)RuCl(3)] (11), whereas the reduction of complex 6 with Zn and NH(4)PF(6) in MeCN yielded [L(OEt)Ru(MeCN)(3)][PF(6)] (12). The reaction of 3·[BF(4)](2) with benzylamine afforded the μ-dinitrogen complex [{L(OEt)Ru(bpy)}(2)(μ-N(2))][BF(4)](2) (13) that was oxidized by [Cp(2)Fe]PF(6) to a mixed valence Ru(II,III) species. The formal potentials of the RuL(OEt) complexes have been determined by cyclic voltammetry. The structures of complexes 5,6,10,11 and 13 have been established by X-ray crystallography.     

New hybrid semiconductor materials based on viologen salts of bimetallic Fe-Pt and Fe-Au carbonyl clusters: first structural characterization of the diradical pi-dimer of the diethylviologen monocation and EPR evidence of its triplet state

The synthesis, structure, spectroscopic characterization and electrical resistivity of the [EtV](2)[Fe(4)Pt(CO)(16)], [EtV][Fe(3)Pt(3)(CO)(15)].THF, [EtV][Fe(4)Au(CO)(16)](2)2.THF (EtV=1,1'-diethyl-4,4'-bipyridilium cation) and [NEt(4)](2)[Fe(4)Au(CO)(16)] is reported. The crystal structure of [EtV](2)[Fe(4)Pt(CO)(16)] is based on infinite stacks of [(EtV)(*+)](2) pi-dimers rotated by 90 degrees and isolated [Fe(4)Pt(CO)(16)](2-) ions. Within each pi-dimer, the [EtV](*+) radical ions are perfectly eclipsed and the distance between their mean planes is 3.275 A. The EPR spectrum of the solid material at room temperature clearly indicates the presence of a significantly populated triplet state of the pi-dimer, by showing signals both at Deltam=1 and Deltam=2. The solid-state structure of [EtV][Fe(3)Pt(3)(CO)(15)].THF is based on the ionic packing of [EtV](2+) and [Fe(3)Pt(3)(CO)(15)](2-) ions, inferred from a comparison of their molecular parameters with literature data. Significant electron transfer could have been expected to give [EtV](*+)[Fe(3)Pt(3)(CO)(15)](*-) on the basis of their formal redox potentials. In spite of their different stoichiometries, the structures of [EtV][Fe(4)Au(CO)(16)](2).2 THF and [NEt(4)](2)[Fe(4)Au(CO)(16)] both contain an isomer of the monoanion [Fe(4)Au(CO)(16)](-) in solution (previously characterized in the solid state as a [NMe(3)CH(2)Ph](2)[Fe(4)Au(CO)(16)]Cl mixed salt). Resistivity measurements on pellets of powdered samples of the above compounds indicate that their tetrasubstituted ammonium salts, and complex [EtV][Fe(4)Au(CO)(16)](2)2.THF, largely behave as insulators. However, the [EtV](2)[Fe(4)Pt(CO)(16)] and [EtV][Fe(3)Pt(3)(CO)(15)].THF samples respectively display resistivities 3 and 4 orders of magnitude less than those of their corresponding ammonium salts and could be classified as semiconductor materials.     

Chiral fluorous dialkoxy-diamino zirconium complexes: synthesis and use in stereospecific polymerization of 1-hexene

New catalysts for the isospecific polymerization of 1-hexene based on cationic zirconium complexes incorporating the tetradentate fluorous dialkoxy-diamino ligands [OC(CF(3))(2)CH(2)N(Me)(CH(2))(2)N(Me)CH(2)C(CF(3))(2)O](2-) [(ON(2)NO)(2-)] and [OC(CF(3))(2)CH(2)N(Me)(1R,2R-C(6)H(10))N(Me)CH(2)C(CF(3))(2)O](2-) [(ON(Cy)NO)(2-)] have been developed. The chiral fluorous diamino-diol [(ON(Cy)NO)H(2), 2] was prepared by ring-opening of the fluorinated oxirane (CF(3))(2)COCH(2) with (R,R)-N,N'-dimethyl-1,2-cyclohexanediamine. Proligand 2 reacts cleanly with [Zr(CH(2)Ph)(4)] and [Ti(OiPr)(4)] precursors to give the corresponding dialkoxy complexes [Zr(CH(2)Ph)(2)(ON(Cy)NO)] (3) and [Ti(OiPr)(2)(ON(Cy)NO)] (4), respectively. An X-ray diffraction study revealed that 3 crystallizes as a 1:1 mixture of two diastereomers (Lambda-3 and Delta-3), both of which adopt a distorted octahedral structure with trans-O, cis-N, and cis-CH(2)Ph ligands. The two diastereomers Lambda-3 and Delta-3 adopt a C(2)-symmetric structure in toluene solution, as established by NMR spectroscopy. Cationic complexes [Zr(CH(2)Ph)(ON(2)NO)(THF)(n)](+) (n=0, anion=[B(C(6)F(5))(4)](-), 5; n=1, anion=[PhCH(2)B(C(6)F(5))(3)](-), 6) and [Zr(CH(2)Ph)(ON(Cy)NO)(THF)](+)[PhCH(2)B(C(6)F(5))(3)](-) (7) were generated from the neutral parent precursors [Zr(CH(2)Ph)(2)(ON(2)NO)] (H) and [Zr(CH(2)Ph)(2)(ON(Cy)NO)] (3), and their possible structures were determined on the basis of (1)H, (19)F, and (13)C NMR spectroscopy and DFT methods. The neutral zirconium complexes H and 3 (Lambda-3/Delta-3 mixture), when activated with B(C(6)F(5))(3) or [Ph(3)C](+)[B(C(6)F(5))(4)](-), catalyze the polymerization of 1-hexene with overall activities of up to 4500 kg PH mol Zr(-1) h(-1), to yield isotactic-enriched (up to 74 % mmmm) polymers with low-to-moderate molecular weights (M(w)=4800-47 200) and monodisperse molecular-weight distributions (M(w)/M(n)=1.17-1.79).     

Group 5 imido complexes derived from diamido-pyridine ligands

Reaction of the vanadium(V) imide [V(NAr)Cl(3)(THF)] (Ar = 2,6-C(6)H(3)(i)()Pr(2)) with the diamino-pyridine derivative MeC(2-C(5)H(4)N)(CH(2)NHSiMe(2)(t)()Bu)(2) (abbreviated as H(2)N'(2)N(py)) gave modest yields of the vanadium(IV) species [V(NAr)(H(3)N'N' 'N(py))Cl(2)] (1 where H(3)N'N' 'N(py) = MeC(2- C(5)H(4)N)(CH(2)NH(2))(CH(2)NHSiMe(2)(t)()Bu) in which the original H(2)N'(2)N(py) has effectively lost SiMe(2)(t)()Bu (as ClSiMe(2)(t)()Bu) and gained an H atom. Better behaved reactions were found between the heavier Group 5 metal complexes [M(NR)Cl(3)(py)(2)] (M = Nb or Ta, R = (t)()Bu or Ar) and the dilithium salt Li(2)[N(2)N(py)] (where H(2)N(2)N(py) = MeC(2-C(5)H(4)N)(CH(2)NHSiMe(3))(2)), and these yielded the six-coordinate M(V) complexes [M(NR)Cl(N(2)N(py))(py)] (M = Nb, R = (t)()Bu 2; M = Ta, R = (t)()Bu 3 or Ar 4). The compounds 2-4 are fluxional in solution and undergo dynamic exchange processes via the corresponding five-coordinate homologues [M(NR)Cl(N(2)N(py))]. Activation parameters are reported for the complexes 2 and 3. In the case of 2, high vacuum tube sublimation afforded modest quantities of [Nb(N(t)()Bu)Cl(N(2)N(py))] (5). The X-ray crystal structures of the four compounds 1, 2, 3, and 4 are reported.     

Unsymmetrical tren-based ligands: synthesis and reactivity of rhenium complexes

Reaction of bis(2-aminoethyl)(3-aminopropyl)amine with C(6)F(6) and K(2)CO(3) in DMSO yields unsymmetrical [(C(6)F(5))HNCH(2)CH(2)](2)NCH(2)CH(2)CH(2)NH(C(6)F(5)) ([N(3)N]H(3)). The tetraamine acts as a tridentate ligand in complexes of the type H[N(3)N]Re(O)X (X = Cl 1, Br 2) prepared by reacting Re(O)X(3)(PPh(3))(2) with [N(3)N]H(3) and an excess of NEt(3) in THF. Addition of 1 equiv of TaCH(CMe(2)Ph)Br(3)(THF)(2) to 1 gives the dimeric compound H[N(3)N]ClReOReBrCl[N(3)N]H (3) in quantitative yield that contains a Re(V)[double bond]O[bond]Re(IV) core with uncoordinated aminopropyl groups in each ligand. Addition of 2 equiv of TaCH(CMe(2)Ph)Cl(3)(THF)(2) to 1 leads to the chloro complex [N(3)N]ReCl (4) with all three amido groups coordinated to the metal, whereas by addition of 2 equiv of TaCH(CMe(2)Ph)Br(3)(THF)(2) to 2 the dibromo species H[N(3)N]ReBr(2) (5) with one uncoordinated amino group is isolated. Reduction of 4 under an atmosphere of dinitrogen with sodium amalgam gives the dinitrogen complex [N(3)N]Re(N(2)) (6). Single-crystal X-ray structure determinations have been carried out on complexes 1, 3, 5, and 6.     

Synthesis, Structure, and Reactivity of [Zr(6)Cl(18)H(5)](2)(-), the First Paramagnetic Species of Its Class

Reaction of [Zr(6)Cl(18)H(5)](3)(-) (1) with 1 equiv of TiCl(4) yields a new cluster anion, [Zr(6)Cl(18)H(5)](2)(-) (2), which can be converted back into [Zr(6)Cl(18)H(5)](3)(-) (1) upon addition of 1 equiv of Na/Hg. Cluster 2 is paramagnetic and unstable in the presence of donor molecules. It undergoes a disproportionation reaction to form 1, some Zr(IV) compounds, and H(2). It also reacts with TiCl(4) to form [Zr(2)Cl(9)](-) (4) and a tetranuclear mixed-metal species, [Zr(2)Ti(2)Cl(16)](2)(-) (3). The oxidation reaction of 1 with TiCl(4) is unique. Oxidation of 1 with H(+) in CH(2)Cl(2) solution results in the formation of [ZrCl(6)](2)(-) (5) and H(2), while in py solution the oxidation product is [ZrCl(5)(py)](-) (6). There is no reaction between 1 and TiI(4), ZrCl(4), [TiCl(6)](2)(-), [ZrCl(6)](2)(-), or CrCl(3). Compounds [Ph(4)P](2)[Zr(6)Cl(18)H(5)] (2a), [Ph(4)P](2)[Zr(2)Ti(2)Cl(16)] (3a), [Ph(4)P](2)[Zr(2)Cl(9)] (4a), [Ph(4)P](2)[ZrCl(6)].4MeCN (5a.4MeCN), and [Ph(4)P][ZrCl(5)(py)] (6a) were characterized by X-ray crystallography. Compound 2a crystallized in the trigonal space group R&thremacr; with cell dimensions (20 degrees C) of a = 28.546(3) ?, b = 28.546(3) ?, c = 27.679(2) ?, V = 19533(3) ?(3), and Z = 12. Compound 3a crystallized in the triclinic space group P&onemacr; with cell dimensions (-60 degrees C) of a = 11.375(3) ?, b = 13.357(3) ?, c = 11.336(3) ?, alpha = 106.07(1) degrees, beta = 114.77(1) degrees, gamma = 88.50(1) degrees, V = 1494.8(7) ?(3), and Z = 1. Compound 4a crystallized in the triclinic space group P&onemacr; with cell dimensions (-60 degrees C) of a = 12.380(5) ?, b = 12.883(5) ?, c = 11.000(4) ?, alpha = 110.39(7) degrees, beta = 98.29(7) degrees, gamma = 73.12(4) degrees, V = 1572(1) ?(3), and Z = 2. Compound 5a.4MeCN crystallized in the monoclinic space group P2(1)/c with cell dimensions (-60 degrees C) of a = 9.595(1) ?, b = 19.566(3) ?, c = 15.049(1) ?, beta = 98.50(1) degrees, V = 2794.2(6) ?(3), and Z = 2. Compound 6a crystallized in the monoclinic space group P2(1)/c with cell dimensions (20 degrees C) of a = 10.3390(7) ?, b = 16.491(2) ?, c = 17.654(2) ?, beta = 91.542(6) degrees, V = 3026.4(5) ?(3), and Z = 4.     

Formation of P-C bonds under unexpectedly mild conditions. Phosphoryl migration and metal coordination of diphenylphosphinomethyl-oxazolines and -thiazolines

The heterocycles 2-methyl-2-oxazoline (mox) and 2-methyl-2-thiazoline (mth) react with Ph2PCl under mild conditions, in the presence of NEt3 which promotes their phosphorylation by stabilization of their enamino tautomers mox(e) and mth(e), respectively, and which also behaves as HCl scavenger. Depending on the reaction conditions, three different phosphine ligands were obtained in good yields from mox: the monophosphine Ph2PCH2C=NCH2CH2O (1ox) and the isomeric diphosphines Ph2PCH=COCH2CH2NPPh2 (2ox) (X-ray structure) and (Ph2P)2CHC=NCH2CH2O (3ox). The formation of these ligands involves phosphoryl migration reactions, which were studied by NMR spectroscopy. The synthesis and the X-ray structures of the corresponding diphenylphosphinothiazolines Ph2PCH2C=NCH2CH2S (1th) and Ph2CH=CSCH2CH2NPPh2 (2th) are also reported but the thiazoline analog of the geminal diphosphine 3ox was not observed. The metal complexes [Pt(3ox-H)2] x 4 CH2Cl2 (4 x 4 CH2Cl2), [Pt(Me)I(1ox)] (5), [Pt(Me)2(1ox)] (7), [Pd(dmba-C,N)(1th)]OTf x 0.25 Et2O (8 x 0.25 Et2O), [Pd(dmba-C,N)(1th-H)] (9), and [9 x {Pd(dmba-C,N)Cl}] x 2.5 C6H6 (10 x 2.5 C6H6) have been prepared and structurally characterized by X-ray diffraction.     

Synthesis and reactions of triphenylsilanethiolato complexes of manganese(II), iron(II), cobalt(II), and nickel(II)

Reactions of Fe[N(SiMe(3))(2)](2) with 1 and 2 equiv of Ph(3)SiSH in hexane afforded dinuclear silanethiolato complexes, [Fe(N(SiMe(3))(2))(mu-SSiPh(3))](2) (1) and [Fe(SSiPh(3))(mu-SSiPh(3))](2) (2), respectively. Various Lewis bases were readily added to 2, generating mononuclear adducts, Fe(SSiPh(3))(2)(L)(2) [L = CH(3)CN (3a), 4-(t)BuC(5)H(4)N (3b), PEt(3) (3c), (LL) = tmeda (3d)]. From the analogous reactions of M[N(SiMe(3))(2)](2) (M = Mn, Co) and [Ni(NPh(2))(2)](2) with Ph(3)SiSH in the presence of TMEDA, the corresponding silanethiolato complexes, M(SSiPh(3))(2)(tmeda) [M = Mn (4), Co (5), Ni (6)], were isolated. Treatment of 3a with (PPh(4))(2)[MoS(4)] or (NEt(4))(2)[FeCl(4)] resulted in formation of a linear trinuclear Fe-Mo-Fe cluster (PPh(4))(2)[MoS(4)(Fe(SSiPh(3))(2))(2)] (7) or a dinuclear complex (NEt(4))(2)[Fe(2)(SSiPh(3))(2)Cl(4)] (8). On the other hand, the reaction of 3a with [Cu(CH(3)CN)(4)](PF(6)) gave a cyclic tetranuclear copper cluster Cu(4)(SSiPh(3))(4) (9), where silanethiolato ligands were transferred from iron to copper. Silicon-sulfur bond cleavage was found to occur when the cobalt complex 5 was treated with (NBu(4))F in THF, and a cobalt-sulfido cluster Co(6)(mu(3)-S)(8)(PPh(3))(6) (10) was isolated upon addition of PPh(3) to the reaction system. The silanethiolato complexes reported here are expected to serve as convenient precursors for sulfido cluster synthesis.     

Copper halide-bridged ruthenium telluride carbonyl complexes: discovery of the semiconducting cluster chain polymer {[PPh4]2[Te2Ru4(CO)10Cu4Br2Cl2].THF}infinity

A new series of Te-Ru-Cu carbonyl complexes was prepared by the reaction of K(2)TeO(3) with [Ru(3)(CO)(12)] in MeOH followed by treatment with PPh(4)X (X=Br, Cl) and [Cu(MeCN)(4)]BF(4) or CuX (X=Br, Cl) in MeCN. When the reaction mixture of K(2)TeO(3) and [Ru(3)(CO)(12)] was first treated with PPh(4)X followed by the addition of [Cu(MeCN)(4)]BF(4), doubly CuX-bridged Te(2)Ru(4)-based octahedral clusters [PPh(4)](2)[Te(2)Ru(4)(CO)(10)Cu(2)X(2)] (X=Br, [PPh(4)](2)[1]; X=Cl, [PPh(4)](2)[2]) were obtained. When the reaction mixture of K(2)TeO(3) and [Ru(3)(CO)(12)] was treated with PPh(4)X (X=Br, Cl) followed by the addition of CuX (X=Br, Cl), three different types of CuX-bridged Te-Ru carbonyl clusters were obtained. While the addition of PPh(4)Br or PPh(4)Cl followed by CuBr produced the doubly CuBr-bridged cluster 1, the addition of PPh(4)Cl followed by CuCl led to the formation of the Cu(4)Cl(2)-bridged bis-TeRu(5)-based octahedral cluster compound [PPh(4)](2)[{TeRu(5)(CO)(14)}(2)Cu(4)Cl(2)] ([PPh(4)](2)[3]). On the other hand, when the reaction mixture of K(2)TeO(3) and [Ru(3)(CO)(12)] was treated with PPh(4)Br followed by the addition of CuCl, the Cu(Br)CuCl-bridged Te(2)Ru(4)-based octahedral cluster chain polymer {[PPh(4)](2)(Te(2)Ru(4)(CO)(10)Cu(4)Br(2)Cl(2)).THF}(infinity) ({[PPh(4)](2)[4].THF}(infinity)) was produced. The chain polymer {[PPh(4)](2)[4].THF}(infinity) is the first ternary Te-Ru-Cu cluster and shows semiconducting behavior with a small energy gap of about 0.37 eV. It can be rationalized as resulting from aggregation of doubly CuX-bridged clusters 1 and 2 with two equivalents of CuCl or CuBr, respectively. The nature of clusters 1-4 and the formation and semiconducting properties of the polymer of 4 were further examined by molecular orbital calculations at the B3LYP level of density functional theory.     

Preparation of mononuclear and dinuclear Rh hydrotris(pyrazolyl)borato complexes containing arenethiolato ligands and conversion of the mononuclear complexes into dinuclear Rh-Rh and Rh-Ir complexes with bridging arenethiolato ligands

Reactions of [Tp*Rh(coe)(MeCN)](; Tp*= HB(3,5-dimethylpyrazol-1-yl)(3); coe = cyclooctene) with one equiv. of the organic disulfides, PhSSPh, TolSSTol (Tol = 4-MeC(6)H(4)), PySSPy (Py = 2-pyridyl), and tetraethylthiuram disulfide in THF at room temperature afforded the mononuclear Rh(III) complexes [Tp*Rh(SPh)(2)(MeCN)](3a), [Tp*Rh(STol)(2)(MeCN)](3b), [Tp*Rh(eta(2)-SPy)(eta(1)-SPy)](6), and [Tp*Rh(eta(2)-S(2)CNEt(2))(eta(1)-S(2)CNEt(2))](7), respectively, via the oxidative addition of the organic disulfides to the Rh(I) center in 1. For the Tp analogue [TpRh(coe)(MeCN)](2, Tp = HB(pyrazol-1-yl)(3)), the reaction with TolSSTol proceeded similarly to give the bis(thiolato) complex [TpRh(STol)(2)(MeCN)](4) as a major product but the dinuclear complex [[TpRh(STol)](2)(micro-STol)(2)](5) was also obtained in low yield. Complex 3 was treated further with the Rh(III) or Ir(III) complexes [(Cp*MCl)(2)(micro-Cl)(2)](Cp*=eta(5)-C(5)Me(5)) in THF at room temperature, yielding the thiolato-bridged dinuclear complexes [Tp*RhCl(micro-SPh)(2)MCp*Cl](8a: M = Rh, 8b: M = Ir). Dirhodium complex [TpRhCl(micro-STol)(2)RhCp*Cl](9) was obtained similarly from 4 and [(Cp*RhCl)(2)(micro-Cl)(2)]. Anion metathesis of 8a proceeds only at the Rh atom with the Cp* ligand to yield [Tp*RhCl(micro-SPh)(2)RhCp*(MeCN)][PF(6)](10), when treated with excess KPF(6) in CH(2)Cl(2)-MeCN. The X-ray analyses have been undertaken to determine the detailed structures of 3b, 4, 5, 6, 7, 8a, 9, and 10.     

Unexpected metal-induced isomerisms and phosphoryl migrations in Pt(II) and Pd(II) complexes of the functional phosphine 2-(bis(diphenylphosphino)methyl)-oxazoline

The reaction of the functional diphosphine 1 [1 = 2-(bis(diphenylphosphino)methyl-oxazoline] with [PtCl(2)(NCPh)(2)] or [PdCl(2)(NCPh)(2)], in the presence of excess NEt(3), affords [Pt{(Ph(2)P)(2)C···C(···NCH(2)CH(2)O)}(2)] ([Pt(1(-H)-P,P)(2)], 3a) and [Pd{(Ph(2)P)(2)C···C(···NCH(2)CH(2)O)}(2)] ([Pd(1(-H)-P,P)(2)], 3b), respectively, in which 1(-H) is (oxazoline-2-yl)bis(diphenylphosphino)methanide. The reaction of 3b with 2 equiv of [AuCl(tht)] (tht = tetrahydrothiophene) afforded [Pd(1(-H)-P,N)(2)(AuCl)(2)] (4), as a result of the opening of the four-membered metal chelate since ligand 1(-H), which was P,P-chelating in 3b, behaves as a P,N-chelate toward the Pd(II) center in 4 and coordinates to Au(I) through the other P donor. In the absence of a base, the reaction of ligand 1 with [PtCl(2)(NCPh)(2)] in MeCN or CH(2)Cl(2) afforded the isomers [Pt{(Ph(2)P)(2)C═C(OCH(2)CH(2)NH)}(2)]Cl(2) ([Pt(1'-P,P)(2)]Cl(2) (5), 1' = 2-(bis(diphenylphosphino)methylene)-oxazolidine) and [Pt{(Ph(2)P)(2)C═C(OCH(2)CH(2)NH)}{Ph(2)PCH═C(OCH(2)CH(2)N(PPh(2))}]Cl(2) ([Pt(1'-P,P)(2'-P,P)]Cl(2) (6), 2' = (E)-3-(diphenylphosphino)-2-((diphenylphosphino)methylene)oxazolidine]. The P,P-chelating ligands in 5 result from a tautomeric shift of the C-H proton of 1 to the nitrogen atom, whereas the formation of one of the P,P-chelates in 6 involves a carbon to nitrogen phosphoryl migration. The reaction of 5 and 6 with a base occurred by deprotonation at the nitrogen to afford 3a and [Pt{(Ph(2)P)(2)C···C(···NCH(2)CH(2)O)}{Ph(2)PCH═COCH(2)CH(2)N(PPh(2))}]Cl ([Pt(1(-H)-P,P)(2'-P,P)]Cl (7)], respectively. In CH(2)Cl(2), an isomer of 3a, [Pt{Ph(2)P)(2)C···C(···NCH(2)CH(2)O)}{Ph(2)PC(PPh(2))═COCH(2)CH(2)N}] ([Pt(1(-H)-P,P)(1(-H)-P,N)] (8)), was obtained as a side product which contains ligand 1(-H) in two different coordination modes. Complexes 3b·4CH(2)Cl(2), 4·CHCl(3), 6·2.5CH(2)Cl(2), and 8·CH(2)Cl(2) have been structurally characterized by X-ray diffraction.     

Synthesis and characterization of heterobimetallic oxo-bridged aluminum-rare earth metal complexes

Reaction of the aluminum hydroxide LAl(OH)[C(Ph)CH(Ph)] (1, L = HC[(CMe)(NAr)](2), Ar = 2,6-iPr(2)C(6)H(3)) with Y(CH(2)SiMe(3))(3)(THF)(2) yielded the oxo-bridged heterobimetallic yttrium dialkyl complex LAl[C(Ph)CH(Ph)](μ-O)Y(CH(2)SiMe(3))(2)(THF)(2) (2). Alkane elimination reaction of 2 with 2-(imino)pyrrole [NN]H ([NN]H = 2-(ArN═CH)-5-tBuC(4)H(2)NH) afforded the yttrium monoalkyl complex LAl[C(Ph)CH(Ph)] (μ-O)Y(CH(2)SiMe(3))[NN](THF)(2) (5). Alternatively, 5 can be prepared in high yield by reaction of 1 with [NN]Y(CH(2)SiMe(3))(2)(THF)(2) (3). The analogous samarium alkyl complex LAl[C(Ph)CH(Ph)](μ-O)Sm(CH(2)SiMe(3))[NN](THF)(2) (6) was prepared similarly. Reactions of 5 and 6 with 1 equiv of iPrOH yielded the corresponding alkoxyl complexes 7 and 8, respectively. The molecular structures of 3, 6, and 8 have been determined by X-ray single-crystal analysis. Complexes 2, 3, 5, 7, and 8 have been investigated as lactide polymerization initiators. The heterobimetallic alkoxyl 8 is highly active to yield high molecular weight (M(n) = 6.91 × 10(4)) polylactides with over 91% conversion at the lactide-to-initiator molar ratio of 2000.     

Hydrosilylation of dienes by yttrium hydrido complexes containing a linked amido-cyclopentadienyl ligand

The dimeric hydrido complex [Y(L)(THF)(mu-H)](2)() containing the CH(2)SiMe(2)-linked amido-cyclopentadienyl ligand L = C(5)Me(4)CH(2)SiMe(2)NCMe(3)(2-) catalyzed the hydrosilylation of 1,5-hexadiene, 1,7-octadiene and vinylcyclohexene by PhSiH(3). As demonstrated for 1,7-octadiene, the product distribution of the hydrosilylation strongly depends on the molar ratio of the reagents. In the absence of PhSiH(3), the stoichiometric reaction of with 1,5-hexadiene gave the isolable crystalline cyclopentylmethyl complex [Y(L)[CH(2)CH(CH(2))(4)](THF)]. Internal olefins such as trans-stilbene and alkynes such as tert-butylacetylene were not hydrosilylated by. trans-Stilbene was inserted into the yttrium-hydride bond of to give the 1,2-diphenylethyl complex [Y(L)[CH(CH(2)Ph)Ph](THF)]. tert-Butylacetylene reacted with to give the dimeric acetylide [Y(L)(C[triple bond]CCMe(3))](2). In an attempt to detect the monomeric hydrido species as a DME adduct [Y(L)H(DME)], complex was reacted with DME to form the sparingly soluble, dimeric 2-methoxyethoxy complex [Y(L)(mu-OCH(2)CH(2)OMe-kappaO)](2) under C-O splitting.