The Parent Diarsene HAs=AsH as side-on bound ligand in an Iron Carbonyl Complex

The terminal diarsene HAs=AsH ligand attracts special interest concerning its bonding relation in comparison to its isolable relative, ethene. Herein, by the methanolysis of [{Fe(CO)4}As(SiMe3)3] (1) the synthesis of [{Fe(CO)4}(η2‐As2H2)] (2) is reported, containing a parent diarsene as unprecedented side‐on coordinated ligand. Following this synthetic route, also the D‐labeled complex [{Fe(CO)4}(η2‐As2D2)] (2D) could be isolated. The electronic structure and bonding situation of 2 was elucidated by DFT calculations revealing that 2 is best described as an olefin‐like complex. Moreover, the reactivity of 2 towards the Lewis acids [{M(CO)5}(thf)] (M=Cr, W) was investigated, leading to the complexes [Fe(CO)4AsHW(CO)5]2 (3) and [{Fe(CO)4}2AsH{Cr(CO)5}] (4), respectively

A General Pathway to Heterobimetallic Triple‐Decker Complexes

A systematic study on the reactivity of the triple-decker complex [(Cp'''Co)(2)(mu,eta(4):eta(4)-C7H8)] (A) (Cp'''=1,2,4-tritertbutyl-cyclopentadienyl) towards sandwich complexes containing cyclo-P-3, cyclo-P-4, and cyclo-P-5 ligands under mild conditions is presented. The heterobimetallic triple-decker sandwich complexes [(Cp*Fe)(Cp'''Co)(mu,eta(5):eta(4)-P-5)] (1) and [(Cp'''Co)(Cp'''Ni)(mu,eta(3):eta(3)-P-3)] (3) (Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) were synthesized and fully characterized. In solution, these complexes exhibit a unique fluxional behavior, which was investigated by variable temperature NMR spectroscopy. The dynamic processes can be blocked by coordination to {W(CO)(5)} fragments, leading to the complexes [(Cp*Fe)(Cp'''Co)(mu(3),eta(5):eta(4):eta(1)-P-5){W(CO)(5)}] (2 a), [(Cp*Fe)(Cp'''Co)(mu(4),eta(5):eta(4):eta(1):eta(1)-P-5){(W(CO)(5))(2)}] (2 b), and [(Cp'''Co)(Cp'''Ni)(mu(3),eta(3):eta(2):eta(1)-P-3){W(CO)(5)}] (4), respectively. The thermolysis of 3 leads to the tetrahedrane complex [(Cp'''Ni)(2)(mu,eta(2):eta(2)-P-2)] (5). All compounds were fully characterized using single-crystal X-ray structure analysis, NMR spectroscopy, mass spectrometry, and elemental analysis

Coordination Behavior of a P4-Butterfly Complex towards Transition Metal Lewis Acids – Preservation versus Rearrangement

The reactivity of the P4 butterfly complex [{Cp’’’Fe(CO)2}2(µ,η1:1‐P4)] (1, Cp’’’ = η5‐C5H2tBu3) towards divalent Co, Ni and Zn salts is investigated. The reaction with the bromide salts leads to [{Cp’’’Fe(CO)2}2(µ3,η2:1:1‐P4){MBr2}] (M = Co (2Co), Ni (2Ni), Zn (2Zn)) where the P4 butterfly scaffold is preserved. The use of the weakly ligated Co complex [Co(NCCH3)6][SbF6]2, results in the formation of [{(Cp’’’Fe(CO)2)2(µ3,η4:1:1‐P4)}2Co][SbF6]3 (3), representing the second example of a homoleptic‐like octaphospha‐metalla‐sandwich complex. The formation of the threefold positively charged complex 3 occurs via redox processes, which among others also enables the formation of [{Cp’’’Fe(CO)2}4(µ5,η4:1:1:1:1‐P8){Co(CO)2}][SbF6] (4), bearing a rare octaphosphabicyclo[3.3.0]octane unit as a ligand. On the other hand, the reaction with [Zn(NCCH3)4][PF6]2 yields the spiro complex [{(Cp’’’Fe(CO)2)2(µ3,η2:1:1‐P4)}2Zn][PF6]2 (5) under preservation of the initial structural motif

Monomeric β‐Diketiminato Group 13 Metal Dipnictogenide Complexes with Two Terminal EH2 Groups (E=P, As)

The pnictogenyl Group 13 compounds (Dipp(2)Nacnac)M[E(SiMe3)(2)]Cl and (Dipp(2)Nacnac)M(EH2)(2) (Dipp(2)Nacnac=HC[C(Me)N(Ar)](2), Ar: Dipp=2,6-iPr(2)C(6)H(3); M=Al, Ga, In; E=P, As) were successfully synthesized. The salt metathesis between (Dipp(2)Nacnac)MCl2 and LiE(SiMe3)(2) only led to monosubstituted compounds (Dipp(2)Nacnac)M[E(SiMe3)(2)]Cl [E=P, M=Ga(1), In (2); E=As, M=Ga (3), In (4)], regardless of the stoichiometric ratios used. In contrast to the steric effect of the SiMe3 groups in 1-4, the reactions of the corresponding halides with LiPH2 center dot DME (or KAsH2) facilely yielded the dipnictogenide compounds (Dipp(2)Nacnac)M(EH2)(2) (E=P, M=Al (5), Ga (6), In (7); E=As, M=Al (8), Ga (9)), avoiding the use of flammable and toxic PH3 and AsH3 for their synthesis. The compounds 5-9 are the first examples of monomeric Group 13 diphosphanides and diarsanides in which the metal center is bound to two terminal PH2 and AsH2 groups, respectively. In contrast to the successful synthesis of the indium diphosphanide (Dipp(2)Nacnac)In(PH2)(2), the reaction of (Dipp(2)Nacnac)InCl2 with KAsH2 led to an indium mirror due to the instability of the target product

Reactivity of E4_4 (E4_4 =P4_4 , As4_4 , AsP3_3) towards Low‐Valent Al(I) and Ga(I) Compounds

The reactivity of yellow arsenic and the interpnictogen compound AsP$_3$ towards low-valent group 13 compounds was investigated. The reactions of [LAl] (1, L=[{N(C$_6$H$_3$$^i$Pr$_2$-2,6)C(Me)}$_2$CH]−) with As$_4$ and AsP$_3$ lead to [(LAl)$_2$(μ,η$^{1:1:1:1}$-E$_4$)] (E$_4$=As$_4$ (3 b), AsP$_3$ (3 c)) by insertion of two fragments [LAl] into two of the six E−E edges of the E$_4$ tetrahedra. Furthermore, the reaction of [LGa] (2) with E$_4$ afforded [LGa(η$^{1:1}$-E$_4$)] (E$_4$=As$_4$ (4 b), AsP$_3$ (4 c)). In these compounds, only one E−E bond of the E$_4$ tetrahedra was cleaved. These compounds represent the first examples of the conversion of yellow arsenic and AsP$_3$, respectively, with group 13 compounds. Furthermore, the reactivity of the gallium complexes towards unsaturated transition metal units or polypnictogen (E$_n$) ligand complexes was investigated. This leads to the heterobimetallic compounds [(LGa)(μ,η$^{2:1:1}$-P$_4$)(LNi)] (5 a), [(Cp’’’Co)(μ,η$^{4:1:1}$-E$_4$)(LGa)] (E=P (6 a), As (6 b), Cp’’’=η$^5$-C$_5$H$_2$$^t$Bu$_3$) and [(Cp’’’Ni)(η$^{3:1:1}$-E$_3$)(LGa)] (E=P (7 a), As (7 b)), which combine two different ligand systems in one complex (nacnac and Cp) as well as two different types of metals (main group and transition metals). The products were characterized by crystallographic and spectroscopic methods

Synthesis and Redox Chemistry of a Homoleptic Iron Arsenic Prismane Cluster

The redox chemistry of the homoleptic iron prismane cluster [{Cp*Fe}3(μ3,η4:4:4-As6)] (A, Cp*=C5Me5) is investigated both electrochemically and synthetically. While its first oxidation leads to the diamagnetic species [{Cp*Fe}3(μ3,η4:4:4-As6)][X] ([1][TEF], [1][FAl], [TEF]−=[Al{OC(CF3)3}4]−, [FAl]−=[FAl{O(1-C6F5)C6F10}3]−), the second oxidation yields the paramagnetic [{Cp*Fe}3(μ3,η4:4:4-As6)][TEF]2 ([2][TEF]2). The reduction of A leads to the monoanionic compound [K@[2.2.2]-cryptand][{Cp*Fe}3(μ3,η4:4:4-As6)] ([K@crypt][3]), while a second reduction could only be traced spectroscopically. All compounds were comprehensively characterized, revealing the structural changes accompanying the described redox processes. All findings are supported by spectroscopic as well as computational studies

Element-Element Bond Formation upon Oxidation and Reduction. Element-Element-Bindungsbildung durch Oxidation und Reduktion

The redox chemistry of [(Cp ''' Co)(2)(mu,eta(2):eta(2)-E-2)(2)] (E=P (1), As (2); Cp '''=1,2,4-tri(tert-butyl)cyclopentadienyl) was investigated. Both compounds can be oxidized and reduced twice. That way, the monocations [(Cp ''' Co)(2)(mu,eta(4):eta(4)-E-4)][X] (E=P, X=BF4 (3 a), [FAl] (3 b); E=As, X=BF4 (4 a), [FAl] (4 b)), the dications [(Cp ''' Co)(2)(mu,eta(4):eta(4)-E-4)][TEF](2) (E=P (5), As (6)), and the monoanions [K(18-c-6)(dme)(2)][(Cp ''' Co)(2)(mu,eta(4):eta(4)-E-4)] (E=P (7), As (8)) were isolated. Further reduction of 7 leads to the dianionic complex [K(18-c-6)(dme)(2)][K(18-c-6)][(Cp ''' Co)(2)(mu,eta(3):eta(3)-P-4)] (9), in which the cyclo-P-4 ligand has rearranged to a chain-like P-4 ligand. Further reduction of 8 can be achieved with an excess of potassium under the formation of [K(dme)(4)][(Cp ''' Co)(2)(mu,eta(3):eta(3)-As-3)] (10) and the elimination of an As-1 unit. Compound 10 represents the first example of an allylic As-3 ligand incorporated into a triple-decker complex

The Butterfly Complex [{Cp*Cr(CO)3}2(μ,η1:1‐P4)] as a Versatile Ligand and Its Unexpected P1/P3 Fragmentation

The versatile coordination behavior of the P(4)butterfly complex [{Cp*Cr(CO)(3)}(2)(mu,eta(1:1)-P-4)] (1) towards Lewis acidic pentacarbonyl compounds of Cr, Mo and W is reported. The reaction of1with [W(CO)(4)(nbd)] (nbd=norbornadiene) yields the complex [{Cp*Cr(CO)(3)}(2)(mu(3),eta(1:1:1:1)-P-4){W(CO)(4)}] (2) in which1serves as a chelating P(4)butterfly ligand. In contrast, reactions of1with [M(CO)(4)(nbd)] (M=Cr (a), Mo (b)) result in the step-wise formation of [{Cp*Cr(CO)(2)}(2)(mu(3),eta(3:1:1)-P-4){M(CO)(5)}] (3 a,b) and [{Cp*Cr(CO)(2)}(2)-(mu(4),eta(3:1:1:1)-P-4){M(CO)(5)}(2)] (4 a,b) which contain a folded cyclo-P(4)unit. Complex4 aundergoes an unprecedented P-1/P-3-fragmentation yielding the cyclo-P(3)complex [Cp*Cr(CO)(2)(eta(3)-P-3)] (5) and the as yet unknown phosphinidene complex [Cp*Cr(CO)(2){Cr(CO)(5)}(2)(mu(3)-P)] (6). The identity of6is confirmed by spectroscopic methods and by the in situ formation of [{Cp*Cr(CO)(2)(tBuNC)}P{Cr(CO)(5)}(2)(tBuNC)] (7). DFT calculations throw light on the bonding situation of the reported products

Nucleophilic Attack at Pentaarsaferrocene [Cp*Fe(η5‐As5)]‐The Way to Larger Polyarsenide Ligands

By the reaction of [Cp*Fe(η5-As5)] (I) (Cp*=C5Me5) with main group nucleophiles, unique functionalized products with η4-coordinated polyarsenide (Asn) units (n=5, 6, 20) are obtained. With carbon-based nucleophiles such as MeLi or KBn (Bn=CH2Ph), the anionic organo-substituted polyarsenide complexes, [Li(2.2.2-cryptand)][Cp*Fe(η4-As5Me)] (1 a) and [K(2.2.2-cryptand)][Cp*Fe{η4-As5(CH2Ph)}] (1 b), are accessible. The use of KAsPh2 leads to a selective and controlled extension of the As5 unit and the formation of the monoanionic compound [K(2.2.2-cryptand][Cp*Fe(η4-As6Ph2)] (2). When I is reacted with [M]As(SiMe3)2 (M=Li ⋅ THF; K), the formation of the largest known anionic polyarsenide unit in [M′(2.2.2-cryptand)]2[(Cp*Fe)4{μ5-η4:η4:η3:η3:η1:η1-As20}] (3) occurred (M′=Li (3 a), K (3 b))

The Potential of the Diphosphorus Complex [Cp2W2(CO)4(ƞ2-P2)] as an Organometallic Connecter in Supramolecular Chemistry

For the first time, the tetrahedral diphosphorus complex [Cp2W2(CO)(4)(mu,eta(2):eta(2)-P-2)] (Cp = C5H5) (3) is used as a connecter in supramolecular chemistry. The treatment of 3 with Cu-I halides leads to the formation of the new one-dimensional (1D) linear polymers [Cu(mu-X){Cp2W2(CO)(4)(mu,eta(2):eta(2):eta(1):eta(1)-P-2)}](n) {X = Cl (4), Br (5), I (6)}. The coordination polymers (CPs) 4-6 are almost insoluble in organic solvents, thus, their P-31 MAS-NMR spectra were recorded and found to be remarkably influenced by their solid-state structures. Additionally, we demonstrate that by reacting the Cp-substituted diphosphorus complex [Cp ' W-2(2)(CO)(4)(mu,eta(2):eta(2)-P-2)] {Cp ' = C5H4{C(CH3)(3)}} (7) with CuBr, the unprecedented soluble 1D CP [Cu(mu-Br){Cp ' W-2(2)(CO)(4)(mu,eta(2):eta(2):eta(1):eta(1)-P-2)}](n) (8) is obtained. Furthermore, the reactions of 3 with the Ag-I salts Ag[CF3SO3] and Ag[PF6] result in the formation of the oligomeric dicationic species [Ag-2{Cp2W2(CO)(4)(mu,eta(2):eta(2):eta(2)-P-2)}(2) {Cp2W2(CO)(4)(mu,eta(2):eta(2):eta(1):eta(1)-P-2)}(2)][X '](2) {X ' = [CF3SO3](-) (9), [PF6](-) (10)}