A novel coordination mode for pentalene in trinuclear chromium complexes.

The first chromium pentalene complexes have been characterized; in these the ligand displays a hitherto-unknown bonding mode whereby a dimeric [Cr(Cp*)](2)(mu-OR) unit is bound (mu:eta(2):eta(2))- to one face, and Cp*Cr is bound eta(5)- to the other. The magnetic properties of these compounds can be understood as the superposition of those of a chromocene and an antiferromagnetically coupled Cr[bond]Cr bonded unit.

Pentalene complexes of group 7 metal carbonyls: an organometallic mixed-valence system with very large metal-metal electronic coupling.

The bimetallic complexes [M(CO)(3)](2)(mu:eta(5):eta(5)-Pn) (Pn = pentalene, C(8)H(6); M = Mn, Re) have been synthesized and characterized crystallographically; the Mn compound was isolated as solely the anti-isomer, while the Re analogue was formed as a mixture of anti- and syn-isomers. [Mn(CO)(3)](2)(mu:eta(5):eta(5)-Pn) may be reduced chemically to its mono- and dianions; the mixed-valence Mn(I)/Mn(0) monoanion is shown by ESR, vibrational, and electronic spectroscopies to be a Robin-Day class III system with an exceptionally large electronic coupling between the metal centers.

Metallocene-terminated allylium salts: the effect of end group on localization in polymethines.

A range of 1,3-di(metallocenyl)allylium salts [Mc(CH)(3)Mc'](+)[X](-) [Mc, Mc' = ferrocenyl (Fc), 2,3,4,5,1',2',3',4'-octamethylferrocen-1-yl (Fc' '), ruthenocenyl (Rc); X = BF(4), PF(6)] was synthesized by reaction of (2-lithiovinyl)metallocenes with formylmetallocenes, followed by treatment of the resulting alcohols with HX. Two salts with X = BAr'(4) [Ar' = 3,5-(CF(3))(2)C(6)H(3)] were synthesized by anion metathesis from the corresponding PF(6) salts. The crystal structure of [Fc' '(CH)(3)Fc' '](+)[PF(6)](-) contains symmetrical termethine cations, while the same appears to be true in the disordered structure of [Fc(CH)(3)Fc](+)[PF(6)](-). The formally unsymmetrical cation in [Fc(CH)(3)Fc' '](+)[BF(4)](-) is only slightly unsymmetrical with little bond-length alternation in the allylium bridge. In contrast, the crystal structures of [Rc(CH)(3)Rc](+)[PF(6)](-) and [Rc(CH)(3)Rc](+)[BAr'(4)](-) both contain a bond-alternated "Peierls-distorted" cation, which can be considered as a ruthenocene bridged to a [(eta(6)-fulvene)(eta(5)-cyclopentadienyl)ruthenium] cation by a vinylene moiety. The strong similarity between solid-state and solution infrared and Raman spectra of [BF(4)](-), [PF(6)](-), and [BAr'(4)](-) salts of [Rc(CH)(3)Rc](+) indicates that the C-C stretching constant in the allylium chain and, therefore, the structure, of this ion are largely independent of the local environment, suggesting that the unsymmetrical structures observed in the crystal structures are not simply an artifact of packing. Differences in the solvatochromism of [Rc(CH)(3)Rc](+) and [Fc(CH)(3)Fc](+) also suggest a localized structure for the former cation in solution. Electrochemistry, UV-visible-NIR spectroscopy, and DF calculations give insight into the electronic structure of the metallocene-terminated allylium cations. Using an analogy between polymethines and mixed-valence compounds, the difference between the behaviors of [Fc(CH)(3)Fc](+) and [Rc(CH)(3)Rc](+) is attributed to larger reorganization energy associated with the geometry differences between metallocene and [(eta(6)-fulvene)(eta(5)-cyclopentadienyl)metal] structures in the ruthenium case.

A non-classical hydrogen bond in the molybdenum arene complex [eta 6-C6H5C6H3(Ph)OH]Mo(PMe3)3: evidence that hydrogen bonding facilitates oxidative addition of the O-H bond.

Mo(PMe3)6 reacts with 2,6-Ph2C6H3OH to give the eta 6-arene complex [eta 6-C6H5C6H3(Ph)OH]Mo(PMe3)3 which exhibits a non-classical Mo...H-OAr hydrogen bond; DFT calculations indicate that the hydrogen bonding interaction facilitates oxidative addition of the O-H bond to give [eta 6,eta 1-C6H5C6H3(Ph)O]Mo(PMe3)2H.

Imide Transfer Properties and Reactions of the Magnesium Imide ((THF)MgNPh)(6): A Versatile Synthetic Reagent.

Imide transfer properties of ((THF)MgNPh)(6) (1) and the synthesis of the related species {(THF)MgN(1-naphthyl)}(6).2.25THF (2), via the reaction of dibutylmagnesium with H(2)N(1-naphthyl), in a THF/heptane mixture are described. Treatment of 1 with Ph(2)CO, 4-Me(2)NC(6)H(4)NO, t-BuNBr(2) (3), PCl(3), or MesPCl(2) (Mes = 2,4,6-Me(3)C(6)H(2)-) leads to the isolation of Ph(2)CNPh (4), 4-Me(2)NC(6)H(4)NNPh (5), t-BuNNPh (6), (PhNPCl)(2) (7), or (MesPNPh)(2) (8) in moderate yield. Reaction between 1 and GeCl(2).dioxane, SnCl(2), or PbCl(2) affords the M(4)N(4) (M = Ge, Sn, Pb) cubane imide derivative (GeNPh)(4) (9), [(SnNPh)(4).{MgCl(2)(THF)(4)}](infinity) (10), (SnNPh)(4).0.5PhMe (11), or (PbNPh)(4).0.5PhMe (12). Interaction of 1 with Ph(3)PO, (Me(2)N)(3)PO, or Ph(2)SO furnishes the complex (Ph(3)POMgNPh)(6) (13), {(Me(2)N)(3)POMgNPh}(6).2PhMe (14), or (Ph(2)SOMgNPh)(6) (15). The addition of 3 equiv of MgBr(2) to 1 gives 1.5 equiv of ((THF)Mg)(6)(NPh)(4)Br(4) (16) in quantitative yield, whereas treatment of 16 with 4 equiv of 1,4-dioxane is an alternative synthetic route to 1. Compounds 2, 3, 9, 10, and 14 were characterized by X-ray crystallography. The reactions demonstrate that 1 is a versatile and useful reagent for the synthesis of a variety of main group imides. Crystal data at 130 K with Mo Kalpha (lambda = 0.710 73 Å) radiation for 3 or Cu Kalpha (lambda = 1.541 78 Å) radiation for 2, 9, 10, and 14: 2, C(93)H(108)Mg(6)N(6)O(7.25), a = 28.101(7) Å, b = 35.851(7) Å, c = 36.816(7) Å, Z = 2, space group Fddd, R = 0.068 for 3500 (I > 2sigma(I)) data; 3, C(4)H(9)Br(2)N, a = 6.682(2) Å, b = 10.834(3) Å, c = 11.080(3) Å, alpha = 66.25(2) degrees, beta = 89.88(2) degrees, gamma = 82.53(2) degrees, Z = 4, space group P&onemacr;, R = 0.038 for 2043 (I > 2sigma(I)) data; 9, C(24)H(20)Ge(4)N(4), a = 10.749(2) Å, b = 12.358(3) Å, c = 35.818(7) Å, Z = 8, space group Pbca, R = 0.040 for 2981 (I > 2sigma(I)) data; 10, C(40)H(52)Cl(2)MgN(4)O(4)Sn(4), a = 12.770(3) Å, b = 13.554(3) Å, c = 25.839(5) Å, Z = 4, space group P2(1)2(1)2(1), R = 0.040 for (I > 2sigma(I)) data; 14, C(86)H(154)Mg(6)N(4)O(6)P(6), a = 22.478(4) Å, b = 16.339(3) Å, c = 29.387(6) Å, Z = 4, space group Pbcn, R = 0.081 for 4696 (I >2sigma(I)) data.