Synthesis of Aluminum Complexes of Triaza Framework Ligands and Their Catalytic Activity toward Polymerization of ε‑Caprolactone

The synthesis and characterization of 1,5-bis­(2,6-diisopropylphenyl)-2,4-diphenyl-1,3,5-triazapenta-1,3-diene (L¹H), a triaza ligand, and Al complexes of its anion are reported. A neat condensation reaction between <i>N</i>-(Dipp)­benzamidine (Dipp = 2,6-diisopropylphenyl) and <i>N</i>-(Dipp)­benzimidoyl chloride affords L¹H in good yield. The Al complexes [L¹AlMe₂] (<b>1</b>), [L¹AlMe­(Cl)] (<b>2</b>), and [L¹AlCl₂] (<b>3</b>) are prepared by treating L¹H with a slight excess of AlMe₃, AlMe₂Cl, and AlMeCl₂, respectively, in toluene. Further, the aluminum complexes [L²AlMe₂] (<b>5</b>), [L²AlMe­(Cl)] (<b>6</b>), and [L²AlCl₂] (<b>7</b>) are obtained in good yields from 1,3-bis­(2-pyridylimino)­isoindoline (L²H) in a similar fashion. The ligand L¹H and complexes <b>1</b>, <b>2</b>, and <b>4</b>–<b>6</b> have been structurally characterized. All of the complexes have been explored for their catalytic activity toward the ring-opening polymerization (ROP) of ε-caprolactone. It has been found that [L¹AlMe₂], upon the addition of cocatalyst (benzyl alcohol), gives a tetranuclear Al alkoxide (<b>8</b>), which is highly efficient in catalyzing the ROP of ε-caprolactone. [L²AlMe₂] has also been found to be a good catalyst. The crystal structure of <b>8</b> and the catalytic activities of all the complexes in detail are reported

Synthesis of Aluminum Complexes of Triaza Framework Ligands and Their Catalytic Activity toward Polymerization of ε‑Caprolactone

The synthesis and characterization of 1,5-bis­(2,6-diisopropylphenyl)-2,4-diphenyl-1,3,5-triazapenta-1,3-diene (L¹H), a triaza ligand, and Al complexes of its anion are reported. A neat condensation reaction between <i>N</i>-(Dipp)­benzamidine (Dipp = 2,6-diisopropylphenyl) and <i>N</i>-(Dipp)­benzimidoyl chloride affords L¹H in good yield. The Al complexes [L¹AlMe₂] (<b>1</b>), [L¹AlMe­(Cl)] (<b>2</b>), and [L¹AlCl₂] (<b>3</b>) are prepared by treating L¹H with a slight excess of AlMe₃, AlMe₂Cl, and AlMeCl₂, respectively, in toluene. Further, the aluminum complexes [L²AlMe₂] (<b>5</b>), [L²AlMe­(Cl)] (<b>6</b>), and [L²AlCl₂] (<b>7</b>) are obtained in good yields from 1,3-bis­(2-pyridylimino)­isoindoline (L²H) in a similar fashion. The ligand L¹H and complexes <b>1</b>, <b>2</b>, and <b>4</b>–<b>6</b> have been structurally characterized. All of the complexes have been explored for their catalytic activity toward the ring-opening polymerization (ROP) of ε-caprolactone. It has been found that [L¹AlMe₂], upon the addition of cocatalyst (benzyl alcohol), gives a tetranuclear Al alkoxide (<b>8</b>), which is highly efficient in catalyzing the ROP of ε-caprolactone. [L²AlMe₂] has also been found to be a good catalyst. The crystal structure of <b>8</b> and the catalytic activities of all the complexes in detail are reported

Heterometallic boride clusters synthesis and characterization of butterfly and square pyramidal boride clusters

International audienceA number of heterometallic boride clusters have been synthesized and structurally characterized using various spectroscopic and crystallographic analyses. Thermolysis of [Ru-3(CO)(12)] with [Cp*WH3(B4H8)] (1) yielded [{Cp* W(CO)(2)}(2)(mu(4)-B){Ru(CO)(3)}(2)(mu-H)] (2), [{Cp*W(CO)(2)}(2) (mu(5) -B){Ru(CO)(3)}(2){Ru(CO)(2)}(mu-H)] (3), [{Cp*W(CO)(2)}(mu(5)-B){Ru(CO)(3)}(4)] (4) and a ditungstaborane cluster [(Cp*W)(2)B4H8Ru(CO)(3)] (5) (Cp*=eta(5)-C5Me5). Compound 2 contains 62 cluster valence-electrons, in which the boron atom occupies the semi-interstitial position of a M-4-butterfly core, composed of two tungsten and two ruthenium atoms. Compounds 3 and 4 can be described as hetero-metallic boride clusters that contain 74-cluster valence electrons (cve), in which the boron atom is at the basal position of the M-5-square pyramidal geometry. Cluster 5 is analogous to known [(Cp*W)(2)B5H9] where one of the BH vertices has been replaced by isolobal {Ru(CO)(3)} fragment. Computational studies with density functional theory (DFT) methods at the B3LYP level have been used to analyze the bonding of the synthesized molecules. The optimized geometries and computed B-11 NMR chemical shifts satisfactorily corroborate with the experimental data. All the compounds have been characterized by mass spectrometry, IR, H-1, B-11 and C-13 NMR spectroscopy, and the structural architectures were unequivocally established by crystallographic analyses of clusters 2-5

Transmetallation vs adduct Diverse reactivity of N,O-ketiminato germylene with [Cp*MCl2]2 (M = Rh or Ir; Cp* = η5-C5Me5) and MCl5 (M = Nb and Ta)

International audienceThe reactions of the germylenes, [(Dipp)NCMeCHCORGeCl] (1a R = Me, 1b R = Ph) with [Ir2Cl2(μ-Cl)2(η5-Cp*)2] led to the formation of the adducts [(Dipp)NCMeCHCORGeClIrCl2Cp*] (3a R = Me and 3b R = Ph). On the other hand, [Rh2Cl2(μ-Cl)2(η5-Cp*)2] does not react with the germylenes (1a and 1b). When the reactions of 1a and 1b are carried out with [Cp*TaCl4], the reaction led to decomposition. The reaction of 1a or 1b with TaCl5 yielded the transmetallated products [(Dipp)NCMeCHCORTaCl4] (4a R = Me, 4b R = Ph) with the extrusion of GeCl2. Our theoretical studies show that for, the insertion of TaCl5 to 1a and the formation of 4a with concomitant elimination of GeCl2 is energetically favourable. Extrusion of SnCl2 is also observed when the corresponding stannylene, [(Dipp)NCMeCHCOMeSnCl] was reacted with TaCl5. All these compounds have been characterized by 1H and 13C NMR spectroscopy, elemental analysis and the constitution of compounds 1b, 3b, and 4a were confirmed by single-crystal X-ray crystallography

Chemistry of group 5 metallaboranes with heterocyclic thiol ligands: a combined experimental and theoretical study

International audienceThermolysis of [(Cp*Nb)(BH)], 1b (Cp* = η-CMe), with 2-mercaptobenzothiazole, CHNSCSH (MBT), and 2-mercaptobenzoxazole, CHNOCSH (MBO), yielded hydrogen substituted compounds 2 and 3 with a general formula [(Cp*Nb)(BH)(BHL)] (2: L = CHNSCS and 3: L = CHNOCS). A similar reaction of 1b with PhSe yielded the monosubstituted derivative [(Cp*Nb)(BH){BH(PhSe)}], 4. All further efforts towards persubstitution of 1b under various drastic conditions were unfruitful. In parallel, in an effort to find a better synthetic route to the known Ta-aziridine complex [Cp*TaBH(CHNS)CHSNCH], Cp*TaCl was treated with a 2-mercaptobenzothiazolyl-based borate ligand Na[HB(CHNSCS)]. Surprisingly, the reaction led to the formation of the half-sandwich trichloroaryltantalum(v) complex [Cp*TaCl{κ-N,S-CHNSCS}], 5, containing a heterocyclic thiol ligand. Using an alternative method complex 5 was isolated in good yield when Cp*TaCl was treated with the potassium salt of 2-mercaptobenzothiazole K[CHNSCS]. All the compounds were characterized by H, B{H}, and C{H} NMR spectroscopy, and their structures were unequivocally established by crystallographic analysis

<i>N</i>‑Benzoylbenzamidinate Complexes of Magnesium: Catalysts for the Ring-Opening Polymerization of ε‑Caprolactone and CO₂/Epoxide Coupling

A series of amidinate-based N,O-chelated magnesium complexes [(<b>L</b>^<b>1</b>)₂(THF)₂Mg] (<b>1</b>), [(<b>L</b>^<b>2</b>)₂(THF)₂Mg] (<b>2</b>), [(<b>L</b>^<b>3</b>)₂(THF)₂Mg] (<b>3</b>), and [(<b>L</b>^<b>4</b>)₂Mg] (<b>4</b>) were prepared by treating <i>N</i>-benzoyl-<i>N</i>′-arylbenzamidines (<b>L</b>^{<b>1</b>–<b>4</b>}H) with 0.5 equiv of di-<i>n</i>-butylmagnesium in THF. Analogous CH₃CN-coordinated complexes [(<b>L</b>^<b>1</b>)₂(CH₃CN)₂Mg] (<b>5</b>) and [(<b>L</b>^<b>3</b>)₂(CH₃CN)₂Mg] (<b>6</b>) were prepared in a similar way using CH₃CN as solvent. All of the compounds were characterized by ¹H/¹³C NMR spectroscopy, and the molecular structures of <b>1</b>, <b>2</b>, and <b>4</b>–<b>6</b> were further confirmed by single-crystal X-ray diffraction studies. Complexes <b>1</b>, <b>2</b>, <b>5</b>, and <b>6</b> displayed good catalytic activity toward the ring-opening polymerization (ROP) of ε-caprolactone. In addition, <b>1</b>, <b>5</b>, and <b>6</b> were also found to be excellent catalysts for making cyclic carbonates from CO₂ and epoxides in the presence of a cocatalyst, <i>n</i>-Bu₄NBr

Reactivity of CS2 – Syntheses and Structures of Transition-Metal Species with Dithioformate and Methanedithiolate Ligands

International audienceThe syntheses and structural characterization of the CS2–metal complexes [(η5-C5Me5M)(η2-S2CH2)(η3-S2CH)] (1: M = Mo; 2: M = W), which feature partially and fully reduced CS2, are reported. In addition, the cis and trans isomers of the dimetallic (sulfido)molybdenum complexes [(η5-C5Me5Mo)2(µ-S2CH2S)2] (3-cis and 4-trans) are described. The [Mo2S4] cores of 3-cis and 4-trans represent paddlewheel-like arrays. All the new compounds were characterized in solution by mass spectrometry, IR spectroscopy, and 1H and 13C NMR spectroscopy. Their structural architectures were established by X-ray crystallographic analysis. Quantum-chemical calculations by DFT methods on the model compounds 1′–4′-trans showed good agreement with the experimentally observed structural parameters. The large HOMO–LUMO (HOMO = highest occupied molecular orbital, LUMO = lowest unoccupied molecular orbital) gaps are consistent with the high thermodynamic stabilities of these complexes. Further, the presence of short metal–metal cross-cluster bonds in the X-ray structures of 3-cis and 4-trans is supported by natural bond order (NBO) calculations. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Synthesis, Structure, Bonding, and Reactivity of Metal Complexes Comprising Diborane(4) and Diborene(2): {Cp*Mo(CO)(2)}(2){mu-eta(2):eta(2)-B2H4}] and {Cp*M(CO)(2)}(2)B2H2M(CO)(4)], M=Mo,W

The reaction of (Cp*Mo)(2)(mu-Cl)(2)B2H6] (1) with CO at room temperature led to the formation of the highly fluxional species {Cp*Mo(CO)(2)}(2){mu-eta(2):eta(2)-B2H4}] (2). Compound 2, to the best of our knowledge, is the first example of a bimetallic diborane(4) conforming to a singly bridged C-s structure. Theoretical studies show that 2 mimics the Cotton dimolybdenum-alkyne complex {CpMo(CO)(2)}(2)C2H2]. In an attempt to replace two hydrogen atoms of diborane(4) in 2 with a 2e W(CO)(4)] fragment, {Cp*Mo(CO)(2)}(2) B2H2W(CO)(4)] (3) was isolated upon treatment with W(CO)(5).thf]. Compound 3 shows the intriguing presence of B2H2] with a short B-B length of 1.624(4) angstrom. We isolated the tungsten analogues of 3, {Cp*W(CO)(2)}(2)B2H2W(CO)(4)] (4) and {Cp*W(CO)(2)}(2)B2H2Mo(CO)(4)] (5), which provided direct proof of the existence of the tungsten analogue of 2

Phenothiazinyl boranes: a new class of AIE luminogens with mega stokes shift, mechanochromism, and mechanoluminescence

Phenothiazines with a dimesityl boron moiety, a new class of aminoboranes with B−N linkage, were synthesized. These aminoboranes exhibited interesting photophysical behavior including aggregation-induced emission (AIE), mechanochromism (MC), mechanoluminescence (ML), and a mega Stokes shift (up to 312 nm in hexane). The solid-state emission of the aminoboranes could be switched reversibly by grinding–fuming processes. Furthermore, the phenothiazine derivative with a bromo and an arylborane group at 3- and 7-positions exhibited bright mechanoluminescence