Secondary Amine Stabilized Aluminum Hydrides Derived from N,N'-Di-tert-butylethylenediamines

The metalation of substituted N,N'-di-tert-butylethylenediamines by various aluminum hydride sources has been investigated. HN(t-Bu)CH(t-Bu)CH(2)N(H)(t-Bu) forms a dimeric lithium chelated adduct of LiAlH(4), [{[HN(t-Bu)CH(t-Bu)CH(2)N(H)(t-Bu)]Li(&mgr;-H)(2)AlH(2)}(2)], 4, which thermally decomposes to yield the tetrameric lithium diamidoaluminum hydride [{Li[N(t-Bu)CH(t-Bu)CH(2)N(t-Bu)]AlH(2)}(4)], 5. The same diamine reacts with AlH(3).NMe(3) or AlH(3) diethyl etherate to give the secondary amine stabilized amidoaluminum hydride species [{HN(t-Bu)CH(t-Bu)CH(2)N(t-Bu)}AlH(2)], 2. Similarly, the same aluminum hydride sources react with the diamine rac-HN(t-Bu)CH(Me)CH(Me)N(H)(t-Bu) to yield [{rac-HN(t-Bu)CH(Me)CH(Me)N(t-Bu)}AlH(2)], 3. Compounds 2 and 3 are stable with respect to elimination of hydrogen to form diamidoaluminum hydrides, but can be converted to the alane rich species, [H(2)Al{N(t-Bu)CH(t-Bu)CH(2)N(t-Bu)}AlH(2)],6, and [H(2)Al{rac-N(t-Bu)CH(Me)CH(Me)N(t-Bu)}AlH(2)], 7, by reaction with AlH(3).NMe(3) under special conditions. The varying reactivity of the three aluminum hydride sources in these reactions has enabled mechanistic information to be gathered, and the effect of the different steric requirements in the diamines on the stability of the complexes is discussed. Crystals of 3are monoclinic, space group P2(1)/n (No. 14), with a = 8.910(4), b = 14.809(1), and c = 12.239(6) ?, beta = 109.76(2) degrees, V = 1520(1) ?(3), and Z = 4. Crystals of 4 are orthorhombic, space group Pbca (No. 61), with a = 15.906(9), b = 24.651(7), and c = 9.933(7) ?, V = 3895(3) ?(3), and Z = 4. Crystals of 6 are monoclinic, space group P2(1)/c (No. 14), with a = 8.392(1), b = 17.513(2), and c = 12.959(1) ?, beta = 107.098(8) degrees, V = 1820.4(3) ?(3), and Z = 4.     

Syntheses, structures, and surface aromaticity of the new carbaalane [(AlH)(6)(AlNMe(3))(2)(CCH(2)R)(6)] (R = Ph, CH(2)SiMe(3)) and a stepwise functionalization of the inner and outer sphere of the cluster

The reaction of the acetylene RC triple bond CH (R = Ph, CH(2)SiMe(3)) with an excess of AlH(3).NMe(3) in boiling toluene leads to the carbaalane [(AlH)(6)(AlNMe(3))(2)(CCH(2)R)(6)] (R = Ph 1, CH(2)SiMe(3) 2) in good yield. Treatment of 2 with BCl(3) under varying conditions gives the chlorinated products [(AlCl)(6)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] 3 and [(AlCl)(6)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(2)Cl)(6)] 4, respectively. The latter clearly demonstrates that the cluster can be stepwise functionalized within the inner and outer sphere. The X-ray single-crystal structures of 1, 2, and 4 have been determined. All compounds have in common that the central core consists of a cluster having eight aluminum and six carbon atoms. The bonding properties in this cluster are described as a new manifestation of three-dimensional surface aromaticity. Each Al(4)C fragment of the cube is formed by four bonds with three electron pairs, thus leading to a strong delocalization of the electrons. A phenomenological modeling using a three-dimensional Hückel scheme with fitted parameters to reproduce the energies from ab initio calculations revealed that the orbital scheme localized at one Al(4)C fragment possesses an orbital sextet with a large HOMO-LUMO gap. This is in line with the criteria of aromaticity. The idea of aromaticity was sustained also by qualitative valence bond reasons enumerating the different resonance structures by means of graph theoretical methods.     

Synthesis of carbaalane halogen derivatives

The carbaalane halogen derivatives [(AlX)(6)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] (X = F (9), Cl (7), Br (10), I (11)) were prepared in toluene from [(AlH)(6)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] (6) and BF(3).OEt(2), BX(3) (X = Br, I), Me(3)SnF, and Me(3)SiX (X = Cl, Br, I), respectively. A partially halogenated product [(AlH)(2)(AlX)(4)(AlNMe(3))(2)(CCH(2)CH(2)SiMe(3))(6)] (12) (X = Cl (approximately 40%), Br (approximately 60%)) was obtained from 5 and impure BBr(3). [(AlH)(6)(AlNMe(3))(2)(CCH(2)Ph)(6)] (5) was converted to [(AlX)(6)(AlNMe(3))(2)(CCH(2)Ph)(6)] (X = F (13), Cl (14), Br (15), I (16)) using BF(3).OEt(2) and Me(3)SiX (X = Cl, Br, I), respectively. The X-ray single-crystal structures of 11.C(6)H(6), 12.3C(7)H(8), 13.6C(7)H(8), and 15.4C(7)H(8) were determined. Compounds 7 and 9-11 are soluble in benzene/toluene and could be well characterized by NMR spectroscopy and MS (EI) spectrometry. The results demonstrate the facile substitution of the hydridic hydrogen atoms in 5 and 6 by the halides with different reagents.     

Synthesis and structures of aluminum alkanethiolate complexes

The homoleptic aluminum thiolate complex [Al(mu-S-t-Bu)(S-t-Bu)(2)](2) was prepared by reacting AlBr(3) with NaS-t-Bu while the analogous 2-propanethiolate complex [Al(mu-S-i-Pr)(S-i-Pr)(2)](2) was synthesized by reacting AlH(3)(OEt(2)) with i-PrSH. In the solid state, the dimers have tetrahedral Al atoms and anti-Al(mu-SR)(2)Al four-member rings. The attempted synthesis of [Al(mu-S-t-Bu)(S-t-Bu)(2)](2) by reacting Al(N-i-Pr(2))(3) with t-BuSH in THF solvent yielded the thermally stable THF adduct Al(S-t-Bu)(3)(THF). The same reaction in diethyl ether solvent produced a mixture of [Al(mu-mgr;-S-t-Bu)(S-t-Bu)(2)](2) and the salt [i-Pr(2)NH(2)][Al(S-t-Bu)(4)]. In the solid-state structure of the salt, the anion [Al(S-t-Bu)(4)](-) has a distorted tetrahedral geometry. Reactions of [Al(NMe(2))(3)](2) and AlH(3)(NMe(2)Et) with the alkanethiols yielded stable amine adducts Al(SR)(3)(R'NMe(2)) (R = i-Pr or t-Bu; R' = H or Et). The ligand adducts Al(S-i-Pr)(3)(HNMe(2)) and Al(S-t-Bu)(3)(THF) have distorted trigonal pyramidal geometries in the solid state. Three of the new compounds, [Al(mu-S-i-Pr)(S-i-Pr)(2)](2) and Al(SR)(3)(HNMe(2)) (R = i-Pr or t-Bu), are viable precursor candidates for the chemical vapor deposition of aluminum sulfide films because they are thermally stable, volatile liquids at moderate temperatures.     

Preparation and characterization of lithium imidoalanate complexes Li(2)[(RN)(4)(AlH(2))(6)] (R = Me or (t)()Bu): first examples of aluminum-rich imidoalanes with an adamantoid structure

Whereas methylammonium chloride, [MeNH(3)]Cl, reacts with LiGaH(4) in an ether solution to give, according to the conditions, either the adduct MeH(2)N x GaH(3) or the cationic derivative [(MeH(2)N)(2)GaH(2)](+)Cl(-), the corresponding reaction of [MeNH(3)]Cl or [(t)BuNH(3)]Cl with LiAlH(4) proceeds mainly, with H(2) elimination, to the imidoalane Li(2)[(RN)(4)(AlH(2))(6)] (R = Me, 1, or (t)Bu, 2). The crystal structure of 1 x 2Et(2)O reveals, for the first time, anionic units with an adamantane-like Al(6)N(4) skeleton. The Li cations exist at two distinct sites, each linked via Li(mu-H)Al bridges to two [(MeN)(4)(AlH(2))(6)](2-) cages. Despite disordering of the tBu groups, the crystal structure of 2 evidently includes analogous anionic units. By contrast, the main product of the reaction between [(i)PrNH(3)]Cl and LiAlH(4) under similar conditions is the known neutral, hexameric imidoalane [(i)PrNAlH](6), 3, the crystal structure of which has been redetermined.     

Synthesis and structural characterization of functionalized dimeric aluminophosphonates and a monomeric gallophosphonate anion

Reaction of t-BuP(O)(OSiMe(3))(OH) with Me(3)Al leads to the formation of [Me(2)Al(mu-O)(2)P(OSiMe(3))(t-Bu)](2) (1) whereas Me(2)AlCl reacts with Ph(2)P(O)(OH) to yield [(Cl)(Me)Al(mu-O)(2)PPh(2)](2) (2). These compounds represent the first examples of functionalized dimeric four-ring type aluminophosphonate systems. The double four-ring type gallophosphonate, namely, [t-BuPO(3)GaMe](4), reacts with n-Bu(4)NHF(2) under ambient conditions, resulting in the formation of a monomeric gallophosphonate [n-Bu(4)N][MeGa[t-BuPO(2)(OH)](3)] (3). These derivatives have been adequately characterized using various spectroscopic techniques and X-ray diffraction studies.     

Reduction reactions of a 1,3,5-triphosphabenzene

The reactions of the triphosphabenzene, 1,3,5-P3C3But3, with LiMH4, M = Al or Ga, lead to the triphosphabicyclo[3.1.0]hexanediyl metallate complexes, [[[Li(OEt2)][MH2(P3C3But3H2)]]2], which give exo- and endo-isomers of a triphosphabicyclo[3.1.0]hexane, P3C3But3H4 upon quenching. The related reaction of [AlH3(NMe3)] with 1,3,5-P3C3But3 affords three identifiable products, viz. a triphosphabicyclo[3.1.0]hexenyl complex, [AlH2(P3C3But3H)(NMe3)], and two triphosphabicyclo[3.1.0]hexanediyl complexes, [AlH(P3C3But3H2)(NMe3)] and [Al2H4(P3C3But3H2)(NMe3)]. In contrast, the reactions of 1,3,5-P3C3But3 with either [GaH3(quin)], quin = quinuclidine, or Me3SnH lead only to the triphosphabicyclo[3.1.0]hexenyl complexes, [GaH2(P3C3But3H)(quin)] and [Me3Sn(P3C3But3H)]. Quenching of the former affords a triphosphabicyclo[3.1.0]hexene, P3C3But3H2, while quenching the latter gives its triphosphacyclohexa-1,4-diene valence isomer. Treatment of 1,3,5-P3C3But3 with "GaI" yields a GaI3 complex of the triphosphahexa-1,4-diene, [GaI3(P3C3But3H2)], whilst treatment with the anionic Ga(I) heterocycle, [:Ga[N(Ar)C(H)]2]-, Ar = C6H3Pri2-2,6, affords the known diphospholyl anion, [1,3-P2C3But3]- via a P-abstraction from the triphosphabenzene. Finally, reaction of the 1,3,5-triphosphacyclohexane, [P(OEt)C(H)(But)]3, with thionyl chloride yields the unusual lambda5, lambda5, lambda5-1,3,5-triphosphacyclohexane, [P(O)(Cl)C(H)(But)]2[P(OEt)(S)C(H)(But)]. Suggestions as to the mechanisms of a number of these reduction reactions are made and the crystal structures of seven compounds are reported.     

Synthesis and characterization of thermally robust amidinato group 13 hydride complexes

The reactivity of two sterically bulky amidines, ArNC(R)N(H)Ar (Ar=2,6-diisopropylphenyl; R=H (HFiso); tBu, (HPiso)) towards LiMH4, M=Al or Ga, [AlH3(NMe3)], and [GaH3(quin)] (quin=quinuclidine) has been examined. This has given rise to a variety of very thermally stable aluminum and gallium hydride complexes. The structural motif adopted by the prepared complexes has been found to be dependent upon both the amidinate ligand and the metal involved. The 1:1 reaction of HFiso with LiAlH4 yielded dimeric [{AlH3(mu-Fiso)Li(OEt2)}2]. Amidine HFiso reacts in a 1:1 ratio with [AlH3(NMe3)] to give the unusual hydride-bridging dimeric complex, [{AlH2(Fiso)}2], in which the Fiso- ligand is nonchelating. The equivalent reaction with the bulkier amidine, HPiso, yielded a related hydride-bridging complex, [{AlH2(Piso)}2], in which the Piso- ligand is chelating. In contrast, the treatment of [GaH3(quin)] with one equivalent of HFiso afforded the four-coordinate complex [GaH2(quin)(Fiso)], in which the Fiso- ligand acts as a localized monodentate amido-imine ligand. The 2:1 reactions of HFiso with [AlH3(NMe3)] or [GaH3(quin)] gave the monomeric complexes [MH(Fiso)2], which are thermally robust and which exhibit chelating amidinate ligands. In contrast, HPiso did not give 2:1 complexes in its reactions with either of the Group 13 trihydride precursors. For sake of comparison, the reactions of [AlH3(NMe3)] and [GaH3(quin)] with the bulky carbodiimide ArN=C=NAr and the thiourea Ar(H)NC(=S)N(H)Ar were examined. These last reactions afforded the five-coordinate thioureido complexes, [MH{N(Ar)C[N(H)(Ar)]S}2], M=Al or Ga.     

Boron and aluminum complexes of sterically demanding phosphinimines and phosphinimides

Reactions of sterically demanding phosphinimines R3PNH [R=i-Pr (1), t-Bu (2)] were examined. Reactions with B(C6F5)3 formed the adducts (R3PNH)B(C6F5)3 [R=i-Pr (3), t-Bu (4)] in high yield. On the other hand, 2 reacts with HB(OBu)2, evolving H2 to give t-Bu3PNB(OBu)2 (5). The reaction of 2 equiv of 2 with BH3.SMe2 affords the species (t-Bu3PN)2BH (6). In contrast, the reaction of n-Bu(t-Bu)2PNH with BH3.SMe2 results in the formation of the robust adduct n-Bu(t-Bu)2PNH.BH3 (8). An alternative route to borane-phosphinimide complexes involves Me3SiCl elimination, as exemplified by the reaction of BCl2Ph with n-Bu3PNSiMe3, which gives the product n-Bu3PNBCl(Ph) (9). The corresponding reactions of the parent phosphinimines 1 and 2 with AlH3.NMe2Et give the dimers [(mu-i-Pr3PN)AlH2]2 (10) and [(mu-t-Bu3PN)AlH2]2 (11). Species 11 reacts further with Me3SiO3SCF3 to provide [(mu-t-Bu3PN)AlH(OSO2CF3)]2 (12). The reaction of the lithium salt [t-Bu3PNLi]4 (13) with BCl3 proceeds smoothly to give t-Bu3PNBCl2 (14), which is readily alkylated to give t-Bu3PNBMe2 (15). Subsequent reaction of 15 with B(C6F5)3 results in methyl abstraction and the formation of [(mu-t-Bu3PN)BMe]2[MeB(C6F5)3]2 (16). The reaction of 13 in a 2:1 ratio with BCl3 gives the salt [(t-Bu3PN)2B]Cl (17). This species can be methylated to give (t-Bu3PN)2BMe (18), which undergoes subsequent reaction with [Ph3C][X] (X=[B(C6F5)4], [PF6]) to form the related salts [(t-Bu3PN)2B][B(C6F5)4] (19) and [(t-Bu3PN)2B][PF6] (20), respectively. Analogous reactions with [Ph3C][BF4] afforded [t-Bu3PNBF2]2 (21). Compounds 3, 4, 6, 8, 11, 12, 17, 19, and 21 were characterized by X-ray crystallography.     

Synthesis and structure of new carborane-substituted cyclotriphosphazenes

The reactions of [N(3)P(3)Cl(6)] with one, two, or three equivalents of the difunctional 1,2-closo-carborane C(2)B(10)H(10)[CH(2)OH](2) and K(2)CO(3) in acetone have been investigated. These reactions led to the new spiro-closo-carboranylphosphazenes gem-[N(3)P(3)Cl(6-2n)[(OCH(2))(2)C(2)B(10)H(10)](n)] (n=1 (1), 2 (2)) and the first fully carborane-substituted phosphazene gem-[N(3)P(3)[(OCH(2))(2)C(2)B(10)H(10)](3)] (3). A bridged product, non-gem-[N(3)P(3)Cl(4)[(OCH(2))(2)C(2)B(10)H(10)]] (4), was also detected. The reaction of the well-known spiro derivatives [N(3)P(3)Cl(2)(O(2)C(12)H(8))(2)] and [N(3)P(3)Cl(4)(O(2)C(12)H(8))] with the same carborane-diol and K(2)CO(3) in acetone gave the new compounds gem-[N(3)P(3)(O(2)C(12)H(8))(3-n)[(OCH(2))(2)C(2)B(10)H(10)](n)] (n=1 (5) or 2 (6), respectively), without signs of intra- or intermolecularly bridged species. Upon treatment with NEt(3) in acetone, compound 5 was converted into the corresponding nido-carboranylphosphazene. However, the reaction of gem-[N(3)P(3)(O(2)C(12)H(8))(2)[(OCH(2))(2)C(2)B(10)H(10)]] (5) with NEt(3) in ethanol instead of acetone proceeded in a different manner to give the new compound (NHEt(3))(2)[N(3)P(3)(O(2)C(12)H(8))(2)(O)[OCH(2)C(2)B(9)H(10)CH(2)OCH(2)CH(3)]] (7). For compounds with two 2,2'-dioxybiphenyl units, gem-[N(3)P(3)(O(2)C(12)H(8))(2)[(OCH(2))(2)C(2)B(10)H(10)]] (5), (NHEt(3))[N(3)P(3)(O(2)C(12)H(8))(2)[(OCH(2))(2)C(2)B(9)H(10)]] (8), and (NHEt(3))(2)[N(3)P(3)(O(2)C(12)H(8))(2)(O)[OCH(2)C(2)B(9)H(10)CH(2)OCH(2)CH(3)]] (7), a mixture of different stereoisomers may be expected. However, for 5 and 7 only the meso compounds seem to be formed, with the same (R,S)-configuration as in the precursor [N(3)P(3)Cl(2)(O(2)C(12)H(8))(2)]. The reaction of 5 to give 8 seems to proceed with a change of configuration at one phosphorus center, giving a racemic mixture. The crystal structures of the nido-carboranylphosphazenes 7 and 8 have been confirmed by X-ray diffraction methods.     

New dinuclear catalysts Rh(2)(N-O)(2)[(C6H4)P(C6H5)2]2 with imidate ligands: synthesis and isomerization from head-to-tail to head-to-head configuration of the imidate ligands

Two new dirhodium(II) catalysts of general formula Rh(2)(N-O)(2)[(C(6)H(4))P(C(6)H(5))(2)](2) (N-O = C(4)H(4)NO(2)) are prepared, starting from Rh(2)(O(2)CCH(3))(2)(PC)(2)L(2) [PC = (C(6)H(4))P(C(6)H(5))(2) (head-to-tail arrangement); L = HO(2)CCH(3)]. The thermal reaction of Rh(2)(O(2)CCH(3))(2)(PC)(2).L(2) with the neutral succinimide stereoselectively gives one compound that according to the X-ray structure determination has the formula Rh(2)(C(4)H(4)NO(2))(2)[(C(6)H(4))P(C(6)H(5))(2)](2) (1). It corresponds to the polar isomer with two bridging imidate ligands in a head-to-head configuration. However, stepwise reaction of Rh(2)(O(2)CCH(3))(2)(PC)(2).L(2) with (CH(3))(3)SiCl and potassium succinimidate yields a mixture of 1 and one of the two possible isomers (structure B) with a head-to-tail configuration of the imidate ligands, Rh(2)(C(4)H(4)NO(2))(2)[(C(6)H(4))P(C(6)H(5))(2)](2) (2), also characterized by X-ray methods. In solution, compound 2 undergoes slow isomerization to 1; the rate of this process is enhanced by the presence of acetonitrile. Compounds 1 and 2 are obtained as pure enantiomers starting from (M)- and (P)-Rh(2)(O(2)CCH(3))(2)(PC)(2).L(2) rather than from the racemic mixture. Their enantioselectivities in cyclopropanation of 1-diazo-5-penten-2-one are similar to those reported for the dirhodium amidate catalysts.     

Neutral and ionic aluminum,gallium, and indium compounds carrying two or three terminal ethynyl groups

The syntheses of the ionic compounds [Li(+).2 dioxane (2,6-iPr(2)C(6)H(3)N(SiMe(3))Al(C triplebond CSiMe(3))(3))(-)].0.75 dioxane (1), [(Li(+))(2).(dioxane)(7)](0.5) [2,6-iPr(2)C(6)H(3)N(SiMe(3))Ga(C triplebond CSiMe(3))(3)(-)].1.5 dioxane (2), and [(Li(+))(2).(dioxane)(7)](0.5) [2,6-iPr(2)C(6)H(3)N(SiMe(3))In(C triplebond CSiMe(3))(3)(-)].1.5 dioxane (3) by the reaction of the corresponding organo metal chloride with LiC triplebond CSiMe(3) are reported. The neutral ethynyl compounds Br-Al(C triplebond CtBu)(2).2 THF (4), Cl-Ga(C triplebond CtBu)(2).THF (5), Cl-In(C triplebond CtBu)(2).2 THF (6), Al(C triplebond CtBu)(3).C[N(Me)CMe](2) (7), Ga(C triplebond CtBu)(3).dioxane (8), and In(C triplebond CtBu)(3).NEt(3) (9) have been obtained in good yields from the reaction of AlBr(3), GaCl(3), and InCl(3) with LiC triplebond CtBu in the presence of a Lewis base. Compound 7 is the first heterocyclic carbene substituted ethynyl derivative. Aluminum and gallium compounds with three terminal ethynyl groups Al(C triplebond CPh)(3).NMe(3) (10) and Ga(C triplebond CPh)(3).NMe(3) (11) have been prepared by the reaction of AlH(3).NMe(3) or GaH(3).NMe(3) with three equivalents of phenylethyne. All the above-mentioned compounds have been structurally studied. In compound 1 the lithium ion is coordinated to the three terminal ethynyl groups, whereas in compounds 2 and 3 the lithium is coordinated to the solvent (dioxane). Compound 8 crystallizes as a coordination polymer with dioxane molecules bridging the individual gallium units.     

(Fluoren-9-ylidene)methanedithiolato complexes of platinum: synthesis, reactivity, and luminescence

Platinum(II) complexes with (fluoren-9-ylidene)methanedithiolato and its 2,7-di-tert-butyl- and 2,7-dimethoxy-substituted analogues were obtained by reacting different chloroplatinum(II) precursors with the piperidinium dithioates (pipH)[(2,7-R2C12H6)CHCS2] [R = H (1a), t-Bu (1b), or OMe (1c)] in the presence of piperidine. The anionic complexes Q2[Pt{S(2)C=C(C12H6R(2)-2,7)}2] [R = H, (Pr(4)N)(2)2a; R = t-Bu, (Pr4N)(2)2b, (Et4N)(2)2b; R = OMe, (Pr4N)(2)2c] were prepared from PtCl(2), piperidine, the corresponding QCl salt, and 1a-c in molar ratio 1:2:2:2. In the absence of QCl, the complexes (pipH)(2)2b and [Pt(pip)(4)]2b were isolated depending on the PtCl(2):pip molar ratio. The neutral complexes [Pt{S2C=C(C12H6R(2)-2,7)L(2)] [L = PPh(3), R = H (3a), t-Bu (3b), OMe (3c); L = PEt(3), R = H (4a), t-Bu (4b), OMe (4c); L(2) = dbbpy, R = H (5a), t-Bu (5b), OMe (5c) (dbbpy = 4,4'-di-tert-butyl-2,2'-bipyridyl)] were similarly prepared from the corresponding precursors [PtCl2L2] and 1a-c in the presence of piperidine. Oxidation of Q(2)2b with [FeCp2]PF6 afforded the mixed Pt(II)-Pt(IV) complex Q2[Pt2{S2C=C[C12H6(t-Bu)(2)-2,7]}4] (Q(2)6, Q = Et4N+, Pr4N+). The protonation of (Pr4N)(2)2b with 2 equiv of triflic acid gave the neutral dithioato complex [Pt2{S2CCH[C12H6(t-Bu)(2)-2,7]}4] (7). The same reaction in 1:1 molar ratio gave the mixed dithiolato/dithioato complex Pr4N[Pt{S2C=C[C12H6(t-Bu)(2)-2,7]}{S2CCH[C12H6(t-Bu)(2)-2,7]}] (Pr(4)N8) while the corresponding DMANH+ salt was obtained by treating 7 with 2 equiv of 1,8-bis(dimethylamino)naphthalene (DMAN). The crystal structures of 3b and 5c.CH2Cl2 have been solved by X-ray crystallography. All the platinum complexes are photoluminescent at 77 K in CH2Cl2 or KBr matrix, except for Q(2)6. Compounds 5a-c and Q8 show room-temperature luminescence in fluid solution. The electronic absorption and emission spectra of the dithiolato complexes reveal charge-transfer absorption and emission energies which are significantly lower than those of analogous platinum complexes with previously described 1,1-ethylenedithiolato ligands and in most cases compare well to those of 1,2-dithiolene complexes.     

Living photolytic ring-opening polymerization of amino-functionalized [1]ferrocenophanes: synthesis and layer-by-layer self-assembly of well-defined water-soluble polyferrocenylsilane polyelectrolytes

Facile synthetic routes have been developed that provide access to cationic and anionic water-soluble polyferrocenylsilane (PFS) polyelectrolytes with controlled molecular weight and narrow polydispersity. Living photolytic ring-opening polymerization of amino-functionalized [1]ferrocenophane (fc) monomers [fcSiMe{C[triple chemical bond]CCH(2)N(SiMe(2)CH(2))(2)}] (3), [fcSi{C[triple chemical bond]CCH(2)N(SiMe(2)CH(2))(2)}(2)] (10), [fcSiMe(C[triple chemical bond]CCH(2)NMe(2))] (14), and [fcSiMe(p-C(6)H(4)CH(2)NMe(2))] (20) yielded the corresponding polyferrocenylsilanes [(fcSiMe{C[triple chemical bond]CCH(2)N(SiMe(2)CH(2))(2)})(n)](5), [(fcSi{C[triple chemical bond]CCH(2)N(SiMe(2)CH(2))(2)}(2))(n)] (11), [{fcSiMe(C[triple chemical bond]CCH(2)NMe(2))}(n)] (15), and [{fcSiMe(p-C(6)H(4)CH(2)NMe(2))}(n)] (21) with controlled architectures. Further derivatization of 5, 15, and 21 generated water-soluble polyelectrolytes [(fcSiMe{C[triple chemical bond]CCH(2)N(CH(2)CH(2)CH(2)SO(3)Na)(2)})(n)] (6), [{fcSiMe(C[triple chemical bond]CCH(2)NMe(3)OSO(3)Me)}(n)] (7), and [{fcSiMe(p-C(6)H(4)CH(2)NMe(3)OSO(3)Me)}(n)] (22), respectively. The polyelectrolytes were readily soluble in water and NaCl aqueous solutions, with 6 and 22 exhibiting long-term stability in aqueous media. The PFS materials 6 and 22, have been utilized in the layer-by-layer (LbL) self-assembly of electrostatic superlattices. Our preliminary studies have indicated that films made from controlled low molecular-weight PFSs possess a considerably thinner bilayer thickness and higher refractive index than those made from PFSs that have an uncontrolled high molecular-weight. These results suggest that the structure and optical properties of LbL ultra-thin films can be tuned by varying polyelectrolyte chain length. The water-soluble low molecular weight PFSs are also useful materials for a range of applications including LbL self-assembly in highly confined spaces.     

Mixed guanidinato/alkylimido/azido tungsten(VI) complexes: synthesis and structural characterization

A series of structurally characterized new examples of pentacoordinated heteroleptic tungsten(VI)-guanidinates complexes are described. Starting out from [WCl(2)(Nt-Bu)(2)py(2)] (1) (py = pyridine) and the guanidinato transfer reagents (TMEDA)Li[(Ni-Pr)(2)CNi-Pr(2)] (2a) (TMEDA = N,N,N',N'-tetramethylethylendiamine) and [Li(NC(NMe(2))(2))](x) (2b), the title compounds [WCl(Nt-Bu)(2)[(Ni-Pr)(2)CNi-Pr(2)]] (3) and [W(Nt-Bu)(2)Cl{NC(NMe(2))(2)]](2) (6) were selectively formed by the elimination of one mole equivalent of lithium chloride. The isopropyl-substituted guanidinato ligand [(Ni-Pr)(2)CNi-Pr(2)} of monomeric 3 is N(1),N(3)-bonded to the tungsten center. The introduction of the sterically less-demanding tetramethyl guanidinato ligand [NC(NMe(2))(2)] expectedly leads to dimeric 6 exhibiting a planar W(2)N(2) ring with the guanidinato group bridging the two tungsten centers via the deprotonated imino N-atom. The remaining chloro ligand of 3 is labile and can be substituted by sterically less-crowded groups such as dimethylamido or azido that yield the presumably monomeric compounds 4 and 5, respectively. A similar treatment of 6 with sodium azide yields the dimeric azido derivative 7. Reacting [WCl(2)(Nt-Bu)(2)py(2)] directly with an excess of sodium azide leads to the dimeric bis-azide species [[W(Nt-Bu)(2)(N(3))(mu(2)-N(3))py](2)]. The new compounds were fully characterized by single-crystal X-ray diffractometry (except 2, 4, and 5), NMR, IR, and mass-spectroscopy as well as elemental analysis. Compound 5, [W(N(3))(Nt-Bu)(2)[(Ni-Pr)(2)CNi-Pr(2)]], can be sublimed at 80 degrees C, 1 Pa.     

Gold(I) phosphido complexes: synthesis, structure, and reactivity

Deprotonation of the phosphine complexes Au(PHR(2))Cl with aqueous ammonia gave the gold(I) phosphido complexes [Au(PR(2))](n)() (PR(2) = PMes(2) (1), PCy(2) (2), P(t-Bu)(2) (3), PIs(2) (4), PPhMes (5), PHMes (6); Mes = 2,4,6-Me(3)C(6)H(2), Is = 2,4,6-(i-Pr)(3)C(6)H(2), Mes = 2,4,6-(t-Bu)(3)C(6)H(2), Cy = cyclo-C(6)H(11)). (31)P NMR spectroscopy showed that these complexes exist in solution as mixtures, presumably oligomeric rings of different sizes. X-ray crystallographic structure determinations on single oligomers of 1-4 revealed rings of varying size (n = 4, 6, 6, and 3, respectively) and conformation. Reactions of 1-3 and 5 with PPN[AuCl(2)] gave PPN[(AuCl)(2)(micro-PR(2))] (9-12, PPN = (PPh(3))(2)N(+)). Treatment of 3 with the reagents HI, I(2), ArSH, LiP(t-Bu)(2), and [PH(2)(t-Bu)(2)]BF(4) gave respectively Au(PH(t-Bu)(2))(I) (14), Au(PI(t-Bu)(2))(I) (15), Au(PH(t-Bu)(2))(SAr) (16, Ar = p-t-BuC(6)H(4)), Li[Au(P(t-Bu)(2))(2)] (17), and [Au(PH(t-Bu)(2))(2)]BF(4) (19).     

Probing the Presence of Multiple Metal-Metal Bonds in Technetium Chlorides by X-ray Absorption Spectroscopy: Implications for Synthetic Chemistry

The cesium salts of [Tc(2)X(8)](3-) (X = Cl, Br), the reduction product of (n-Bu(4)N)[TcOCl(4)] with (n-Bu(4)N)BH(4) in THF, and the product obtained from reaction of Tc(2)(O(2)CCH(3))(4)Cl(2) with HCl(g) at 300 °C have been characterized by extended X-ray absorption fine structure (EXAFS) spectroscopy. For the [Tc(2)X(8)](3-) anions, the Tc-Tc separations found by EXAFS spectroscopy (2.12(2) ? for both X = Cl and Br) are in excellent agreement with those found by single-crystal X-ray diffraction (SCXRD) measurements (2.117[4] ? for X = Cl and 2.1265(1) ? for X = Br). The Tc-Tc separation found by EXAFS in these anions is slightly shorter than those found in the [Tc(2)X(8)](2-) anions (2.16(2) ? for X = Cl and Br). Spectroscopic and SCXRD characterization of the reduction product of (n-Bu(4)N)[TcOCl(4)] with (n-Bu(4)N)BH(4) are consistent with the presence of dinuclear species that are related to the [Tc(2)Cl(8)](n-) (n = 2, 3) anions. From these results, a new preparation of (n-Bu(4)N)(2)[Tc(2)Cl(8)] was developed. Finally, EXAFS characterization of the product obtained from reaction of Tc(2)(O(2)CCH(3))(4)Cl(2) with HCl(g) at 300 °C indicates the presence of amorphous α-TcCl(3). The Tc-Tc separation (i.e., 2.46(2) ?) measured in this compound is consistent with the presence of Tc═Tc double bonds in the [Tc(3)](9+) core.     

New diamide-diamine ligands and their zirconium and hafnium dichloride and bis(dimethylamide) complexes

The multigram syntheses of the protio ligands (2-NC(5)H(4))CH(2)N(CH(2)CH(2)NHSiMe(2)R)(2) (R = Me, H(2)N(2)NN' 3; R = (t)Bu, H(2)N(2)NN() 4) are described via reactions of the previously reported (2-NC(5)H(4))CH(2)N(CH(2)CH(2)NH(2))(2) (1). A new synthesis of 1 is reported starting from 2-aminomethylpyridine and N-tosylaziridine, proceeding via (2-NC(5)H(4))CH(2)N(CH(2)CH(2)NHTs)(2) (2). Reaction of H(2)N(2)NN' or H(2)N(2)NN* with (n)BuLi gives good yields of the dilithiated derivatives Li(2)N(2)NN' and Li(2)N(2)NN*. Reaction of H(2)N(2)NN' or H(2)N(2)NN* with [MCl(2)(CH(2)SiMe(3))(2)(Et(2)O)(2)] gives the cis-dichloride complexes [MCl(2)(L)] (L = N(2)NN', M = Zr 7 or Hf 8; L = N(2)NN(), M = Zr 9). The corresponding reactions of H(2)N(2)NN' or H(2)N(2)NN* with [Zr(NMe(2))(4)] afford the bis(dimethylamide) derivatives [Zr(NMe(2))(2)(L)] (L = N(2)NN' 10 or N(2)NN* 11). All of these protonolysis reactions proceed smoothly and in good yields. Attempts to prepare the titanium complexes [Ti(X)(2)(N(2)NN')] (X = Cl or NMe(2)) were unsuccessful. The X-ray crystal structures of (2-NC(5)H(4))CH(2)N(CH(2)CH(2)NHTs)(2).EtOH, [ZrCl(2)(N(2)NN')].0.5C(6)H(6), [Zr(NMe(2))(2)(N(2)NN')], and [Zr(NMe(2))(2)(N(2)NN*)] are reported.     

1,2-Distanna-closo-dodecaborate--a rare example of a 1,2-distannylene ligand in transition metal chemistry

The coordination chemistry of the novel bidentate tin ligand 1,2-distanna-closo-dodecaborate is illustrated for the first time by reactions with molybdenum, platinum and gold metal complexes. Up to three clusters coordinate two metal centers in close proximity. For all these metal complexes the typical μ-bridging coordination mode was observed exclusively. Furthermore, two cluster anions react with dichloromethane via substitution of the chloride ions. The carbon functionalized tin cluster [Et(4)N](2)[CH(2)(Sn(2)B(10)H(10))(2)] and the coordination complexes [Et(3)NMe](6)[Mo(2)(CO)(6)(Sn(2)B(10)H(10))(3)], [Et(3)NMe](2)[{HPt(PEt(3))(2)(Sn(2)B(10)H(10))}(2)], [Et(4)N](2)[{HPt(PPh(3))(2)(Sn(2)B(10)H(10))}(2)] and [{(TP)Au}(2)(Sn(2)B(10)H(10))] (TP = PhP(o-Ph(2)PC(6)H(4))(2)) are fully characterized by multinuclear NMR spectroscopy, elemental analyses and crystal structure analyses.     

Catalytic dehydrocoupling of Me2NHBH3 with Al(NMe2)3

The catalytic dehydrocoupling reaction of Me(2)NHBH(3) with Al(NMe(2))(3) gives the dimer [Me(2)NBH(2)](2) and the chain [(Me(2)N)(2)BH], involving the thermally-stable Al(III) hydride catalyst [{(Me(2)N)(2)BH(2)}(2)AlH].