Oxidative cleavage of tetraaryltetraphosphane-1,4-diides by nickel(II) and palladium(II): formation of unusual Ni(0) and Pd(0) diaryldiphosphene complexes

[Na(2)(thf)(4)(P(4)Mes(4))] (1) (Mes = 2,4,6-Me(3)C(6)H(2)) reacts with one equivalent of [NiCl(2)(PEt(3))(2)], [NiCl(2)(PMe(2)Ph)(2)], [PdCl(2)(PBu(n)(3))(2)] or [PdCl(2)(PMe(2)Ph)(2)] to give the corresponding nickel(0) and palladium(0) dimesityldiphosphene complexes [Ni(eta(2)-P(2)Mes(2))(PEt(3))(2)] (2), [Ni(eta(2)-P(2)Mes(2))(PMe(2)Ph)(2)] (3), [Pd(eta(2)-P(2)Mes(2))(PBu(n)(3))(2)] (4) and [Pd(eta(2)-P(2)Mes(2))(PMe(2)Ph)(2)] (5), respectively, via a redox reaction. The molecular structures of the diphosphene complexes 2-5 are described.     

Catalytic addition of amine N-H bonds to carbodiimides by half-sandwich rare-earth metal complexes: efficient synthesis of substituted guanidines through amine protonolysis of rare-earth metal guanidinates

Reaction of [Ln(CH(2)SiMe(3))(3)(thf)(2)] (Ln=Y, Yb, and Lu) with one equivalent of Me(2)Si(C(5)Me(4)H)NHR' (R'=Ph, 2,4,6-Me(3)C(6)H(2), tBu) affords straightforwardly the corresponding half-sandwich rare-earth metal alkyl complexes [{Me(2)Si(C(5)Me(4))(NR')}Ln(CH(2)SiMe(3))(thf)(n)] (1: Ln = Y, R' = Ph, n=2; 2: Ln = Y, R' = C(6)H(2)Me(3)-2,4,6, n=1; 3: Ln = Y, R' = tBu, n=1; 4: Ln = Yb, R' = Ph, n=2; 5: Ln = Lu, R' = Ph, n=2) in high yields. These complexes, especially the yttrium complexes 1-3, serve as excellent catalyst precursors for the catalytic addition of various primary and secondary amines to carbodiimides, efficiently yielding a series of guanidine derivatives with a wide range of substituents on the nitrogen atoms. Functional groups such as C[triple chemical bond]N, C[triple chemical bond]CH, and aromatic C--X (X: F, Cl, Br, I) bonds can survive the catalytic reaction conditions. A primary amino group can be distinguished from a secondary one by the catalyst system, and therefore, the reaction of 1,2,3,4-tetrahydro-5-aminoisoquinoline with iPrN==C==NiPr can be achieved stepwise first at the primary amino group to selectively give the monoguanidine 38, and then at the cyclic secondary amino unit to give the biguanidine 39. Some key reaction intermediates or true catalyst species, such as the amido complexes [{Me(2)Si(C(5)Me(4))(NPh)}Y(NEt(2))(thf)(2)] (40) and [{Me(2)Si(C(5)Me(4))(NPh)}Y(NHC(6)H(4)Br-4)(thf)(2)] (42), and the guanidinate complexes [{Me(2)Si(C(5)Me(4))(NPh)}Y{iPrNC(NEt(2))(NiPr)}(thf)] (41) and [{Me(2)Si(C(5)Me(4))(NPh)}Y{iPrN}C(NC(6)H(4)Br-4)(NHiPr)}(thf)] (44) have been isolated and structurally characterized. Reactivity studies on these complexes suggest that the present catalytic formation of a guanidine compound proceeds mechanistically through nucleophilic addition of an amido species, formed by acid-base reaction between a rare-earth metal alkyl bond and an amine N--H bond, to a carbodiimide, followed by amine protonolysis of the resultant guanidinate species.     

On the nature of actinide- and lanthanide-metal bonds in heterobimetallic compounds

Eleven experimentally characterized complexes containing heterobimetallic bonds between elements of the f-block and other elements were examined by quantum chemical methods: [(η(5)-C(5)H(5))(2)(THF)LuRu(η(5)-C(5)H(5))(CO)(2)], [(η(5)-C(5)Me(5))(2)(I)ThRu(η(5)-C(5)H(5))(CO)(2)], [(η(5)-C(5)H(5))(2)YRe(η(5)-C(5)H(5))(2)], [{N(CH(2)CH(2)NSiMe(3))(3)}URe(η(5)-C(5)H(5))(2)], [Y{Ga(NArCh)(2)}{C(PPh(2)NSiH(3))(2)}(CH(3)OCH(3))(2)], [{N(CH(2)CH(2)NSiMe(3))(3)}U{Ga(NArCH)(2)}(THF)], [(η(5)-C(5)H(5))(3)UGa(η(5)-C(5)Me(5))], [Yb(η(5)-C(5)H(5)){Si(SiMe(3))(3)(THF)(2)}], [(η(5)-C(5)H(5))(3)U(SnPh(3))], [(η(5)-C(5)H(5))(3)U(SiPh(3))], and (Ph[Me]N)(3)USi(SiMe(3))(3). Geometries in good agreement with experiment were obtained at the density functional level of theory. The multiconfigurational complete active space self-consistent field method (CASSCF) and subsequent corrections with second order perturbation theory (CASPT2) were applied to further understand the electronic structure of the lanthanide/actinide-metal (or metal-metalloid) bonds. Fragment calculations and energy-decomposition analyses were also performed and indicate that charge transfer occurs from one supported metal fragment to the other, while the bonding itself is always dominated by ionic character.     

Reactions of trialkoxynitridomolybdenum with low-coordinate phosphorus compounds containing a P=N double bond

The reactions of N≡Mo(OR)(3) (R = (t)Bu, (i)Pr) with (Me(3)Si)(2)NPNSiMe(3) (1), (Me(3)Si)(2)NPN(t)Bu (2), (Me(3)Si)(2)NPS(N(t)Bu) (3) and (Me(3)Si)(2)NP(NSiMe(3))(2) (4) have been studied. Reported complexes were synthesized via 1,2-addition of an Mo-OR bond across the P=N bond, resulting in four-membered metallacycles of the corresponding σ(2)λ(3)-iminophosphine or σ(3)λ(5)-iminophosphorane with trialkoxynitridomolybdenum. The structure of all new compounds was elucidated by (1)H, (13)C and (31)P NMR spectroscopy. Compounds [(Me(3)Si)(2)N-P(NSiMe(3))(O-(t)Bu)]{((t)BuO)(2)Mo≡N} (5), [(Me(3)Si)(2)N-PS(N(t)Bu)(O-(t)Bu)]{((t)BuO)(2)Mo≡N} (7), [(Me(3)Si)(2)N-P(NSiMe(3))(2)(O-(t)Bu)]{((t)BuO)(2)Mo≡N} (8) and [(Me(3)Si)(2)N-P(NSiMe(3))(2)(O-(i)Pr)]{((i)PrO)(2)Mo≡N} (12) were also characterized by single X-ray analysis and shown to be metallacycles containing the Mo atom with an intact terminal nitrido ligand.     

Molybdenocene trihydride complexes: influence of a [Me2Si] ansa bridge on classical versus nonclassical nature, stability with respect to elimination of dihydrogen, and acidity

Experimental and computational studies on a series of cationic molybdenocene trihydride complexes, namely [Cp(2)MoH(3)]+, [(Cp(Bu)t)(2)MoH(3)]+, [Cp(2)MoH(3)]+, and ([Me(2)Si(C(5)Me(4))(2)]MoH(3))+, demonstrate that the most stable form for the ansa molybdenocene derivative is a nonclassical dihydrogen-hydride isomer, ([Me(2)Si(C(5)Me(4))(2)]Mo(eta(2)-H(2))(H))+, whereas the stable forms for the non-ansa complexes are classical trihydrides, [Cp(2)Mo(H)(3)]+, [(Cp(Bu)t)(2)Mo(H)(3)]+, and [Cp(2)Mo(H)(3)]+. In addition to altering the classical versus nonclassical nature of [Cp(2)MoH(3)]+ and ([Me(2)Si(C(5)Me(4))(2)]Mo(eta(2)-H(2))(H))+, the [Me(2)Si] ansa bridge also markedly influences the stability of the complex with respect to elimination of H(2) and dissociation of H+. Finally, computational studies on ([H(2)Si(C(5)H(4))(2)]MoH(2)D)+ and ([H(2)Si(C(5)H(4))(2)]MoHD(2))+ establish that deuterium exhibits a greater preference than hydrogen to occupy dihydrogen versus hydride sites.     

Si-H and Si-Si activation at Pt: synthesis and reactivity of neutral and cationic silyl complexes

Reactions of [Pt(PEt(3))(3)] (1) with the silanes HSiPh(3), HSiPh(2)Me and HSi(OEt)(3) led to the products of oxidative addition, cis-[Pt(H)(SiPh(3))(PEt(3))(2)] (2), cis-[Pt(H)(SiPh(2)Me)(PEt(3))(2)] (3), cis-[Pt(H){Si(OEt)(3)}(PEt(3))(2)] (cis-4) and trans-[Pt(H){Si(OEt)(3)}(PEt(3))(2)] (trans-4). The complexes cis-4 and trans-4 can also be generated by hydrogenolysis of (EtO)(3)SiSi(OEt)(3) in the presence of 1. Furthermore, the silyl compounds cis-4 and trans-4 react with B(C(6)F(5))(3) and CH(3)CN by hydride abstraction to give the cationic silyl complex trans-[Pt{Si(OEt)(3)}(NCCH(3))(PEt(3))(2)][HB(C(6)F(5))(3)] (8). In addition, the reactivity of the complexes cis-4, trans-4 and 8 towards alkenes and CO was studied using NMR experiments.     

Yttrium and lanthanide complexes having a chiral phosphanylamide in the coordination sphere

The chiral phosphanylamides {N(R-CHMePh)(PPh(2))}(-) and {N(S-CHMePh)(PPh(2))}(-) were introduced into rare earth chemistry. Transmetalation of the enantiomeric pure lithium compounds Li{N(R-CHMePh)(PPh(2))} (1a) and Li{N(S-CHMePh)(PPh(2))} (1b) with lanthanide bis(phosphinimino)methanide dichloride [{CH(PPh(2)NSiMe(3))(2)}LnCl(2)](2) in a 2:1 molar ratio in THF afforded the enantiomeric pure complexes [{CH(PPh(2)NSiMe(3))(2)}Ln(Cl){eta(2)-N(R-CHMePh)(PPh(2))}] (Ln = Er (2a), Yb (3a), Lu (4a)) and [{CH(PPh(2)NSiMe(3))(2)}Ln(Cl){eta(2)-N(S-CHMePh)(PPh(2))}] (Ln = Er (2b), Yb (3b), Lu (4b)). The solid-state structures of 2a and 3a,b were established by single-crystal X-ray diffraction. Attempts to synthesize compounds 3 in a one-pot reaction starting from K{CH(PPh(2)NSiMe(3))(2)}, YbCl(3), and 1 resulted in the lithium chloride incorporated complex [{(Me(3)SiNPPh(2))(2)CH}Yb(mu-Cl)(2)LiCl(THF)(2)] (5). In an alternative approach to give chiral rare earth compounds in a one-pot reaction 1a or 1b was reacted with LnCl(3) and K(2)C(8)H(8) to give the enantiomeric pure cyclooctatetraene compounds [{eta(2)-N(R-CHMePh)(PPh(2))}Ln(eta(8)-C(8)H(8))] (Ln = Y (6a), Er (7a), Yb (8)) and [{eta(2)-N(S-CHMePh)(PPh(2))}Ln(eta(8)-C(8)H(8))] (Ln = Y (6b), Er (7b)). The structures of 6a,b, 7a, and 8 were confirmed by single-crystal X-ray diffraction in the solid state.     

Application of molybdenum bis(imido) complexes in ethylene dimerisation catalysis

In combination with EtAlCl(2) (Mo : Al = 1 : 15) the imido complexes [MoCl(2)(NR)(NR')(dme)] (R = R' = 2,6-Pr(i)(2)-C(6)H(3) (1); R = 2,6-Pr(i)(2)-C(6)H(3), R' = Bu(t) (3); R = R' = Bu(t) (4); dme = 1,2-dimethoxyethane) and [Mo(NHBu(t))(2)(NR)(2)] (R = 2,6-Pr(i)(2)-C(6)H(3) (5); R = Bu(t) (6)) each show moderate TON, activity, and selectivity for the catalytic dimerisation of ethylene, which is influenced by the nature of the imido substituents. In contrast, the productivity of [MoCl(2)(NPh)(2)(dme)] (2) is low and polymerisation is favoured over dimerisation. Catalysis initiated by complexes 1-4 in combination with MeAlCl(2) (Mo : Al = 1 : 15) exhibits a significantly lower productivity. Reaction of complex 5 with EtAlCl(2) (2 equiv.) gives rise to a mixture of products, while addition of MeAlCl(2) affords [MoMe(2)(N-2,6-Pr(i)(2)-C(6)H(3))(2)]. Treatment of 6 with RAlCl(2) (2 equiv.) (R = Me, Et) yields [Mo({μ-N-Bu(t)}AlCl(2))(2)] (7) in both cases. Imido derivatives 1 and 3 react with Me(3)Al and MeAlCl(2) to form the bimetallic complexes [MoMe(2)(N{R}AlMe(2){μ-Cl})(NR')] (R = R' = 2,6-Pr(i)(2)-C(6)H(3) (8); R = 2,6-Pr(i)(2)-C(6)H(3), R' = Bu(t) (10)) and [MoMe(2)(N{R}AlCl(2){μ-Cl})(NR')] (R = R' = 2,6-Pr(i)(2)-C(6)H(3) (9); R = 2,6-Pr(i)(2)-C(6)H(3), R' = Bu(t) (11)), respectively. Exposure of complex 8 to five equivalents of thf or PMe(3) affords the adducts [MoMe(2)(N-2,6-Pr(i)(2)-C(6)H(3))(2)(L)] (L = thf (12); L = PMe(3) (13)), while reaction with NEt(3) (5 equiv.) yields [MoMe(2)(N-2,6-Pr(i)(2)-C(6)H(3))(2)]. The molecular structures of complexes 5, 9 and 11 have been determined.     

Donor-acceptor-stabilized silicon analogue of an acid anhydride

A stable silicon analogue of an acid anhydride {PhC(Bu(t)N)(2)}Si{═O·B(C(6)F(5))(3)}O-Si(H){═O·B(C(6)F(5))(3)}{(NBu(t))(HNBu(t))CPh} (4) with a O═Si-O-Si═O core has been prepared by treating monochlorosilylene PhC(Bu(t)N)(2)SiCl (1) with H(2)O·B(C(6)F(5))(3) in the presence of NHC (NHC = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene). Compound 4 has been characterized by elemental analysis and multinuclear NMR spectroscopic investigations. The molecular structure of 4 has been established by single-crystal X-ray diffraction studies, and DFT calculations support the experimental results.     

Synthesis and structures of aluminum and magnesium complexes of tetraimidophosphates and trisamidothiophosphates: EPR and DFT investigations of the persistent neutral radicals {Me2Al[(mu-NR)(mu-NtBu)P(mu-NtBu)2]Li(THF)2}(*) (R = SiMe3, tBu)

Reactions of (RNH)(3)PNSiMe(3) (3a, R = (t)()Bu; 3b, R = Cy) with trimethylaluminum result in the formation of {Me(2)Al(mu-N(t)Bu)(mu-NSiMe(3))P(NH(t)()Bu)(2)]} (4) and the dimeric trisimidometaphosphate {Me(2)Al[(mu-NCy)(mu-NSiMe(3))P(mu-NCy)(2)P(mu-NCy)(mu-NSiMe(3))]AlMe(2)} (5a), respectively. The reaction of SP(NH(t)Bu)(3) (2a) with 1 or 2 equiv of AlMe(3) yields {Me(2)Al[(mu-S)(mu-N(t)Bu)P(NH(t)()Bu)(2)]} (7) and {Me(2)Al[(mu-S)(mu-N(t)()Bu)P(mu-NH(t)Bu)(mu-N(t)Bu)]AlMe(2)} (8), respectively. Metalation of 4 with (n)()BuLi produces the heterobimetallic species {Me(2)Al[(mu-N(t)Bu)(mu-NSiMe(3))P(mu-NH(t)()Bu)(mu-N(t)()Bu)]Li(THF)(2)} (9a) and {[Me(2)Al][Li](2)[P(N(t)Bu)(3)(NSiMe(3))]} (10) sequentially; in THF solutions, solvation of 10 yields an ion pair containing a spirocyclic tetraimidophosphate monoanion. Similarly, the reaction of ((t)BuNH)(3)PN(t)()Bu with AlMe(3) followed by 2 equiv of (n)BuLi generates {Me(2)Al[(mu-N(t)Bu)(2)P(mu(2)-N(t)Bu)(2)(mu(2)-THF)[Li(THF)](2)} (11a). Stoichiometric oxidations of 10 and 11a with iodine yield the neutral spirocyclic radicals {Me(2)Al[(mu-NR)(mu-N(t)Bu)P(mu-N(t)Bu)(2)]Li(THF)(2)}(*) (13a, R = SiMe(3); 14a, R = (t)Bu), which have been characterized by electron paramagnetic resonance spectroscopy. Density functional theory calculations confirm the retention of the spirocyclic structure and indicate that the spin density in these radicals is concentrated on the nitrogen atoms of the PN(2)Li ring. When 3a or 3b is treated with 0.5 equiv of dibutylmagnesium, the complexes {Mg[(mu-N(t)()Bu)(mu-NH(t)()Bu)P(NH(t)Bu)(NSiMe(3))](2)} (15) and {Mg[(mu-NCy)(mu-NSiMe(3))P(NHCy)(2)](2)} (16) are obtained, respectively. The addition of 0.5 equiv of MgBu(2) to 2a results in the formation of {Mg[(mu-S)(mu-N(t)()Bu)P(NH(t)Bu)(2)](2)} (17), which produces the hexameric species {[MgOH][(mu-S)(mu-N(t)()Bu)P(NH(t)Bu)(2)]}(6) (18) upon hydrolysis. Compounds 4, 5a, 7-11a, and 15-17 have been characterized by multinuclear ((1)H, (13)C, and (31)P) NMR spectroscopy and, in the case of 5a, 9a.2THF, 11a, and 18, by X-ray crystallography.     

Half-sandwich o-N,N-dimethylaminobenzyl complexes over the full size range of group 3 and lanthanide metals. synthesis, structural characterization, and catalysis of phosphine P--H bond addition to carbodiimides

The acid-base reactions between the rare-earth metal (Ln) tris(ortho-N,N-dimethylaminobenzyl) complexes [Ln(CH2C(H4NMe2-o)3] with one equivalent of the silylene-linked cyclopentadiene-amine ligand (C5Me4H)SiMe2NH(C6H2Me3-2,4,6) afforded the corresponding half-sandwich aminobenzyl complexes [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}Ln(CH2C6H4NMe2-o)(thf)] (2-Ln) (Ln=Y, La, Pr, Nd, Sm, Gd, Lu) in 60-87 % isolated yields. The one-pot reaction between ScCl(3) and [Me2Si(C5Me4)(NC6H2Me3-2,4,6)]Li2 followed by reaction with LiCH2C6H4NMe2-o in THF gave the scandium analogue [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}Sc(CH2C6H4NMe2-o)] (2-Sc) in 67 % isolated yield. 2-Sc could not be prepared by the acid-base reaction between [Sc(CH2C6H4NMe2-o)3] and (C5Me4H)SiMe2NH(C6H2Me3-2,4,6). These half-sandwich rare-earth metal aminobenzyl complexes can serve as efficient catalyst precursors for the catalytic addition of various phosphine P--H bonds to carbodiimides to form a series of phosphaguanidine derivatives with excellent tolerability to aromatic carbon-halogen bonds. A significant increase in the catalytic activity was observed, as a result of an increase in the metal size with a general trend of La>Pr, Nd>Sm>Gd>Lu>Sc. The reaction of 2-La with 1 equiv of Ph2PH yielded the corresponding phosphide complex [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}La(PPh2)(thf)2] (4), which, on recrystallization from benzene, gave the dimeric analogue [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}La(PPh2)]2 (5). Addition of 4 or 5 to iPrN=C=NiPr in THF yielded the phosphaguanidinate complex [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}La{iPrNC(PPh2)NiPr}(thf)] (6), which, on recrystallization from ether, afforded the ether-coordinated structurally characterizable analogue [{Me2Si(C5Me4)(NC6H2Me3-2,4,6)}La{iPrNC(PPh2)NiPr}(OEt2)] (7). The reaction of 6 or 7 with Ph2PH in THF yielded 4 and the phosphaguanidine iPrN=C(PPh2)NHiPr (3a). These results suggest that the catalytic formation of a phosphaguanidine compound proceeds through the nucleophilic addition of a phosphide species, which is formed by the acid-base reaction between a rare-earth metal o-dimethylaminobenzyl bond and a phosphine P--H bond, to a carbodiimide, followed by the protonolysis of the resultant phosphaguanidinate species by a phosphine P--H bond. Almost all of the rare earth complexes reported this paper were structurally characterized by X-ray diffraction studies.     

Luminescent amidate-bridged one-dimensional platinum(II)-thallium(I) coordination polymers assembled via metallophilic attraction

The neutral square-planar complexes [Pt(RNH2)2(NHCO(t)Bu)2] (R = H, 1; Et, 2) and [Pt(DACH)(NHCO(t)Bu)2] (DACH = 1,2-diaminocyclohexane, 3) act as metalloligands and make bonds to closed-shell Tl(I) ions to afford one- and two-dimensional platinum-thallium oligomers or polymers based on heterobimetallic backbones. A series of heteronuclear platinum(II)-thallium(I) complexes have been synthesized and structurally characterized. The structures of the Pt-Tl compounds resulted from [Pt(RNH2)2(NHCO(t)Bu)2] and TlX [X = NO3(-), ClO4(-), PF6(-), and Cp2Fe(CO2)2(2-)] are dependent on both counteranions and the amine substituents. The compounds [Pt(NH3)2(NHCO(t)Bu)2Tl]X (X = NO3(-), 8; ClO4(-), 9) adopt one-dimensional zigzag chain structures consisting of repeatedly stacked [Pt(NH3)2(NHCO(t)Bu)2Tl]+ units, whereas [{Pt(NH3)2(NHCO(t)Bu)2}2Tl2]X2 (X = PF6(-), 10) consists of a helical chain. Compound 3 reacts with Tl+ to give [{Pt(DACH)(NHCO(t)Bu)2}2Tl](NO3) x [Pt(DACH)(NHCO(t)Bu)2] x 3 H2O (14) and one-dimensional polymeric [{Pt(DACH)(NHCO(t)Bu)2}2Tl2]X2 (X = ClO4(-), 15; PF6(-), 16). Reactions of [Pt(DACH)(NHCOCH3)2] with Tl+ ions afford one-dimensional coordination polymers [{Pt(DACH)(NHCOCH3)2}2Tl2]X2 (X = NO3(-), 17; ClO4(-), 18; PF6(-), 19). The polymeric [{Pt(DACH)(NHCOR')2}2Tl2]2+ (R = CH3, (t)Bu) complexes adopt helical structures, which are generated around the crystallographic 2(1) screw axis. The distance between the coils corresponds to the unit cell length, which ranges from 22.58 to 22.68 A. The platinum-thallium bond distances fall in a narrow range around 3.0 A. The complexes derived from [Pt(NH3)2(NHCO(t)Bu)2] are luminescent at 77 K. The trinuclear complexes [{Pt(RNH2)(NHCO(t)Bu)2}2Tl]+ do not emit at room temperature but are emissive at 77 K, whereas the polymeric platinum-thallium complexes containing 1,2-diaminocyclohexane are intensively luminescent at both room temperature and 77 K. The color variations are interesting; 15 exhibits intense yellow-green, 16 exhibits green, and 17-19 exhibit blue luminescence. The presence of bonding between platinum and thallium is supported by the short metal-metal separations and the strong low-energy luminescence of these compounds in their solid states.     

Alkyne coupling at a rhenium-monocarborane substrate: synthesis of Re,B-eta2:sigma-butadienyl complexes

Treatment of 7-NH(2)Bu(t)-nido-7-CB(10)H(12) in tetrahydrofuran (THF) with LiBu(n)(3 equiv) and then [ReBr(CO)(3)(THF)(2)] gives the rhenacarborane dianion [1-NHBu(t)-2,2,2-(CO)(3)-closo-2,1-ReCB(10)H(10)](2-), isolated as the bis-[N(PPh(3))(2)](+) salt (4). Iodine oxidation of this Re(I) intermediate gives the Re(III) complex [1,2-mu-NHBu(t)-2,2,2-(CO)(3)-closo-2,1-ReCB(10)H(10)] 6 in which the carborane functions formally as an 8-electron (6pi+ 2sigma) donor. Reaction of with ligands L in the presence of Me(3)NO gives substituted products [1,2-mu-NHBu(t)-2,2-(CO)(2)-2-L-closo-2,1-ReCB(10)H(10)][L = PPh(3)(7a), CNXyl (7b; Xyl = C(6)H(3)Me(2)-2,6), or Bu(t)C triple bond CH (7c)]. Formation of complex 7c is unexpectedly accompanied by [1,2-mu-NHBu(t)-2,2-(CO)(2)-3,2-sigma:eta(2)-{C(=CHBu(t))-CH=CHBu(t)}-closo-2,1-ReCB(10)H(9)] 8a, in which an alkyne-derived dienyl group is bound to both the rhenium centre and to an adjacent boron vertex. Complex 8a is also obtained from 7c with Bu(t)C triple bond CH and Me(3)NO. The same reaction of 7c, using PhC triple bond CH or CNXyl instead of Bu(t)C triple bond CH, gives, respectively, [1,2-micro-NHBu(t)-2,2-(CO)(2)-3,2-sigma:eta(2)-{C(=CHBu(t))-CH=CHPh}-closo-2,1-ReCB(10)H(9)] 8b and [1,2-micro-NHBu(t)-2-Bu(t)C triple bond CH-2-CO-2-CNXyl-closo-2,1-ReCB(10)H(10)] 9. Addition of donors L to results in displacement from rhenium of the pendant dienyl moiety, yielding [1,2-mu-NHBu(t)-2,2-(CO)(2)-2-L-3-{C(=CHBu(t))-CH=CHBu(t)}-closo-2,1-ReCB(10)H(9)][L = PMe(3)(10a), CNBu(t)(10b)]. Single-crystal X-ray diffraction analyses have confirmed the novel structural features of compounds 6, 7c, 8b and 9.     

Reaction of N≡W(O(t)Bu)3 with σ3λ5-phosphoranes. The [2 + 2] cycloaddition across the W≡N triple bond results in the first representative of an inorganic four-membered metallacycle with conjugated endo- and exocyclic double bonds

The reactions of N≡W(O(t)Bu)(3) with the low-coordinate phosphorus compounds (Me(3)Si)(2)NP(NSiMe(3))(2) (I) and (Me(3)Si)(2)NPS(N(t)Bu) (II) were studied. Quantum chemical calculations were used to determine why Mo- and W-containing compounds with the same composition have different molecular structures.     

Titanium tert-butoxyimido compounds

The synthesis and molecular and electronic structures of the first tert-butoxyimido complexes of titanium (TiNO(t)Bu functional group) are reported, featuring a variety of mono- or poly-dentate, neutral or anionic N-donor ligands. Reaction of Ti(NMe(2))(2)Cl(2) with (t)BuONH(2) gave good yields of Ti(NO(t)Bu)Cl(2)(NHMe(2))(2) (1). Compound 1 serves as an excellent entry point into new tert-butoxyimido complexes by reaction with a variety of fac-N(3) donor ligands, namely, Me(3)[9]aneN(3) (trimethyl-1,4,7-triazacyclononane), HC(Me(2)pz)(3) (tris(3,5-dimethylpyrazolyl)methane), or Me(3)[6]aneN(3) (trimethyl-1,3,5-triazacyclohexane) to give Ti(NO(t)Bu)(Me(3)[9]aneN(3))Cl(2) (2), Ti(NO(t)Bu){HC(Me(2)pz)(3)}Cl(2) (3), or Ti(NO(t)Bu)(Me(3)[6]aneN(3))Cl(2) (4) in good yield. It was found that 4 could be converted into Ti(NO(t)Bu)Cl(2)(py)(3) (5) in very good yield by reaction with an excess of pyridine. Compound 5 is effective in a range of salt metathesis reactions with lithiated amide or pyrrolide ligands, and reacts with Li(2)N(2)N(py), Li(2)N(2)N(Me), LiN(pyr)N(Me(2)), or Li(2)N(2)(pyr)N(Me) to give Ti(N(2)N(py))(NO(t)Bu)(py) (6), Ti(N(2)N(Me))(NO(t)Bu)(py) (7), Ti(N(pyr)N(Me(2)))(NO(t)Bu)Cl(py)(2) (9), or Ti(N(2)(pyr)N(Me))(NO(t)Bu)(py)(2) (10) in moderate to good yields (N(2)N(py) = (2-NC(5)H(4))C(Me)(CH(2)NSiMe(3))(2); N(2)N(Me) = MeN(CH(2)CH(2)NSiMe(3))(2); N(pyr)N(Me(2)) = Me(2)NCH(2)(2-NC(4)H(3)); N(2)(pyr)N(Me) = MeN{CH(2)(2-NC(4)H(3))}(2)). Compounds 7, 9, and 10 reacted with 2,2'-bipyridyl by pyridine exchange reactions forming Ti(N(2)N(Me))(NO(t)Bu)(bipy) (8), Ti(N(pyr)N(Me(2)))(NO(t)Bu)Cl(bipy) (11), and Ti(N(2)(pyr)N(Me))(NO(t)Bu)(bipy) (12). Ten tert-butoxyimido compounds, namely, 1-6, 11, and 12, have been structurally characterized revealing approximately linear Ti-N-O(t)Bu linkages with Ti-N distances [range 1.686(2)-1.734(2) ?] that are generally intermediate between those in the homologous alkylimido and phenylimido analogues, and shorter than in the diphenylhydrazido counterparts. Density functional theory (DFT) studies on the model compounds Ti(NR)Cl(2)(NHMe(2))(2) (1_R; R = OMe, Me, Ph, NMe(2)) confirmed this trend and found that the destabilizing effect of the -OMe oxygen 2p(π) lone pair on one of the Ti-N π-bonds in 1_OMe is comparable to that of the occupied phenyl ring π orbitals in the phenylimido homologue 1_Ph but much less than for the -NMe(2) nitrogen lone pair in 1_NMe(2).     

Synthesis and structures of a 3-sila-beta-diketiminatomagnesium bromide, ketenimide and triflate

The crystalline compounds [Mg(Br)(L)(thf)].0.5Et2O [L = {N(R)C(C6H3Me2-2,6)}2SiR, R = SiMe3] (1), [Mg(L){N=C=C(C(Me)=CH)2CH2}(D)2] [D = NCC6H3Me2-2,6 (2), thf (3)] and [{Mg(L)}2{mu-OSO(CF3)O-[mu}2] (4) were prepared from (a) Si(Br)(R){C(C6H3Me2-2,6)=NR}2 and Mg for (1), (b) [Mg(SiR3)2(thf)2] and 2,6-Me2C6H3CN (5 mol for (2), 3 mol for (3)), and (c) (2) + Me3SiOS(O)2CF3 for (4); a coproduct from (c) is believed to have been the trimethylsilyl ketenimide Me3SiN=C=C{C(Me)=CH}2CH2 (5).     

The preparation and characterisation of hetero- and homobimetallic complexes containing bridging naphthalene-1,8-dithiolato ligands

Homo- and heterobimetallic complexes of the form [(PPh(3))(2)(mu(2)-1,8-S(2)-nap){ML(n)}] (in which (1,8-S(2)-nap)=naphtho-1,8-dithiolate and {ML(n)}={PtCl(2)} (1), {PtClMe} (2), {PtClPh} (3), {PtMe(2)} (4), {PtIMe(3)} (5) and {Mo(CO)(4)} (6)) were obtained by the addition of [PtCl(2)(NCPh)(2)], [PtClMe(cod)] (cod=1,5-cyclooctadiene), [PtClPh(cod)], [PtMe(2)(cod)], [{PtIMe(3)}(4)] and [Mo(CO)(4)(nbd)] (nbd=norbornadiene), respectively, to [Pt(PPh(3))(2)(1,8-S(2)-nap)]. Synthesis of cationic complexes was achieved by the addition of one or two equivalents of a halide abstractor, Ag[BF(4)] or Ag[ClO(4)], to [{Pt(mu-Cl)(mu-eta(2):eta(1)-C(3)H(5))}(4)], [{Pd(mu-Cl)(eta(3)-C(3)H(5))}(2)], [{IrCl(mu-Cl)(eta(5)-C(5)Me(5))}(2)] (in which C(5)Me(5)=Cp*=1,2,3,4,5-pentamethylcyclopentadienyl), [{RhCl(mu-Cl)(eta(5)-C(5)Me(5))}(2)], [PtCl(2)(PMe(2)Ph)(2)] and [{Rh(mu-Cl)(cod)}(2)] to give the appropriate coordinatively unsaturated species that, upon treatment with [(PPh(3))(2)Pt(1,8-S(2)-nap)], gave complexes of the form [(PPh(3))(2)(mu(2)-1,8-S(2)-nap){ML(n)}][X] (in which {ML(n)}[X]={Pt(eta(3)-C(3)H(5))}[ClO(4)] (7), {Pd(eta(3)-C(3)H(5))}[ClO(4)] (8), {IrCl(eta(5)-C(5)Me(5))}[ClO(4)] (9), {RhCl(eta(5)-C(5)Me(5))}[BF(4)] (10), {Pt(PMe(2)Ph)(2)}[ClO(4)](2) (11), {Rh(cod)}[ClO(4)] (12); the carbonyl complex {Rh(CO)(2)}[ClO(4)] (13) was formed by bubbling gaseous CO through a solution of 12. In all cases the naphtho-1,8-dithiolate ligand acts as a bridge between two metal centres to give a four-membered PtMS(2) ring (M=transition metal). All compounds were characterised spectroscopically. The X-ray structures of 5, 6, 7, 8, 10 and 12 reveal a binuclear PtMS(2) core with PtM distances ranging from 2.9630(8)-3.438(1) A for 8 and 5, respectively. The napS(2) mean plane is tilted with respect to the PtP(2)S(2) coordination plane, with dihedral angles in the range 49.7-76.1 degrees and the degree of tilting being related to the PtM distance and the coordination number of M. The sum of the Pt(1)coordination plane/napS(2) angle, a, and the Pt(1)coordination plane/M(2)coordination plane angle, b, a+b, is close to 120 degrees in nearly all cases. This suggests that electronic effects play a significant role in these binuclear systems.     

Carbophosphazene-supported ligand systems containing pyrazole/guanidine coordinating groups

Carbophosphazene-based coordination ligands [{NC(NMe(2))}(2){NP(3,5-Me(2)Pz)(2)}] (1), [{NC(NEt)(2)}{NC(3,5-Me(2)Pz)}{NP(3,5-Me(2)Pz)(2)}] (2), [NC(3,5-Me(2)Pz)](2)[NP(3,5-Me(2)Pz)(2)] (3), [{NCCl}(2){NP(NC(NMe(2))(2))(2)}] (4), and [{NC(p-OC(5)H(4)N)}(2){NP(NC(NMe(2))(2))(2)}] (5) were synthesized and structurally characterized. In these compounds, the six-membered C(2)N(3)P ring is perfectly planar. The reaction of 1 with CuCl(2) afforded [{NC(NMe(2))}(2){NHP(O)(3,5-Me(2)Pz)}·{Cu(3,5-Me(2)PzH)(2)(Cl)}][Cl] (6). The ligand binds to Cu(II) utilizing the geminal [P(O)(3,5-Me(2)Pz)] coordinating unit. Similarly, the reaction of 2 with PdCl(2) afforded, after a metal-assisted P-N hydrolysis, [{NC(NEt)(2)}{NC(3,5-Me(2)Pz)}{NP(O)(3,5-Me(2)Pz)}·{Pd(3,5-Me(2)PzH)(Cl)}] (7). In the latter, the [P(O)(3,5-Me(2)Pz)] unit does not coordinate; in this instance, the Pd(II) is bound by a ring nitrogen atom and a carbon-tethered pyrazolyl nitrogen atom. The reaction of 3 with PdCl(2) also results in P-N bond hydrolysis affording [{NC(3,5-Me(2)Pz)(2)}{NP(O)(3,5-Me(2)Pz)}{Pd(Cl)}] (8). In contrast to 7, however, in 8, the Pd(II) elicits a nongeminal η(3) coordination from the ligand involving two carbon-tethered pyrazolyl groups and a ring nitrogen atom. Metalated products could not be isolated in the reaction of 3 with K(2)PtCl(4). Instead, a P-O-P bridged carbodiphosphazane dimer, [{NC(3,5-Me(2)Pz)NHC(3,5-Me(2)Pz)}{NP(O)}](2) (9), was isolated as the major product. Finally, the reaction of 5 with PdCl(2) resulted in [{NC(OC(5)H(4)N)}(2){NP(NC(NMe(2))(2))(2)}·{PdCl(2)}] (10). In the latter, the exocyclic P-N bonds are quite robust and are involved in binding to the metal ion. Compounds 6-10 have been characterized by a variety of techniques including X-ray crystallography. In all of the compounds, the bond parameters of the inorganic heterocyclic rings are affected by metalation.     

One-dimensional silver(I) coordination polymers containing cyclodiphosphazane, cis-{(o-MeOC(6)H(4)O)P(mu-N(t)Bu)}(2)

The 1:1 reaction between the cyclodiphosphazane cis-{(o-MeOC(6)H(4)O)P(mu-N(t)Bu)}(2) (1) and AgOTf afforded one-dimensional Ag(I) coordination polymer [Ag{mu-OTf-kappaO,kappaO}{mu-(o-MeOC(6)H(4)O)P(mu-N(t)Bu)-kappaP,kappaP}(2)](infinity) (2) containing bridging cyclodiphosphazane and trifluoromethanesulfonate (OTf) ligands. The 2:1 reaction of and AgOTf leads to the formation of simple mononuclear complex [Ag{OTf-kappaO,kappaO}({(o-MeOC(6)H(4)O)P(mu-N(t)Bu)-kappaP}(2))(2)] (3) in quantitative yield. Reaction of 1 with AgCN produces a strain-free zig-zag coordination polymer [({(o-MeOC(6)H(4)O)P(mu-N(t)Bu)-kappaP,kappaP}(2))(2)Ag(NCAgCN)](infinity) (4) irrespective of reaction stoichiometry and conditions. In complexes 3 and 4 cyclodiphosphazanes coordinate to Ag(I) centers in a monodentate fashion. Single crystal structures were established for the Ag(I) polymers 2 and 4.     

Synthesis,Properties, Structure and Reactivity of Sodium 2,3,4,5-Tetra- tert -butylcyclopentaphosphanide

The reaction between Na, t BuPCl 2 , and PCl 3 in thf gives Na[ cyclo -( t Bu 4 P 5 )] ( 1 ). 1 reacts with PCl 3 to yield ( cyclo - t Bu 3 P 4 ) t BuPCl ( 2 ), and with a proton source, such as HCl, NH 4 Cl, or t BuCl, to give cyclo - t Bu 4 P 5 H ( 3 ). The reaction of 1 with [MCl 2 (PRR' 2 ) 2 ] (M = Ni; R = R' = Et; M = Pd, Pt, R = Ph, R' = Me) gives [Ni{ cyclo -( t Bu 3 P 5 )}(PEt 3 ) 2 ] ( 4 ), [Pd{ cyclo -( t Bu 4 P 5 )} 2 ] ( 5 ), and [PtCl{ cyclo -( t Bu 3 P 4 ) t BuP}(PPhMe 2 )] ( 6 ). 1-6 were characterized by 31 P{ 1 H} NMR spectroscopy, and 1 and 4-6 were also characterized by X-ray crystallography.