Wolfgang Milius

16- and 18-Electron Cp*Rh complexes with 1,2-dicarba-closo-dodecaborane(12)-1,2-dichalcogenolato ligands, as studied by multinuclear magnetic resonance

The reaction of [Cp*RhCl2](2) 1 with dilithium 1,2-dicarba-closo-dodecaborane(12)-1,2-dithiolate (a) and -diselenolate (b) afforded the 16-electron rhodium(III) half-sandwich complexes Cp*Rh[E2C2(B10H10)] [E=S (3a), Se (3b)]. The 18-electron trimethylphosphane rhodium(III) half-sandwiches Cp*Rh(PMe3)[E2C2(B10H10)] 4a-c were prepared from the reaction of Cp*RhCl2(PMe3) 2 with the same dichalcogenolates, including the ditelluride (c). The complexes 4a,b could also be obtained from the reaction of 3a,b with trimethylphosphane. The molecular geometry of 4b was determined by X-ray structural analysis. The 16-electron complexes 3 an monomeric in solution as shown by multinuclear magnetic resonance (H-1-, B-11-, C-13-, P-31- Se-77-, Rh-103-, Te-125-NMR). also in comparison with the data for the trimethylphosphane analogues 4a-c and for 6a in which the rhodium bears the eta(5)-1,3-C5H3 Bu-t(2) ligand. The Rh-103 nuclear shielding is reduced by 831 ppm (3a) and 1114 ppm (3b) with respect to the 18-electron complexes 4a,b. Similarly, the Se-77 nuclear shielding in 3b is reduced by 676.4 ppm with respect to that in 4b

Rhodium‐Induced Selective B(3)/B(6)‐Disubstitution of ortho‐Carborane‐1,2‐dithiolate

The various reactive sites in the 16 e complex 1 invite addition reactions with alkynes. After addition of 2 to one of the Rh-S bonds, B-H activation takes place which finally leads to the complex 3, in which a B(3)/B(6)-disubstituted o-carborane cage is present for the first time.

Metal-Induced B−H Activation: Addition of Acetylene, Propyne, or 3-Methoxypropyne to Rh(Cp*), Ir(Cp*), Ru(p-cymene), and Os(p-cymene) Half-Sandwich Complexes Containing a Chelating 1,2-Dicarba-closo-dodecaborane-1,2-dichalcogenolato Ligand

The addition reactions of the 16e half-sandwich complexes [M(eta5-Cp*)[E2C2(B10H10)]] (Cp*=pentamethylcyclopentadienyl: 1S: E=S, M=Rh; 2S: E=S; M=Ir; 2Se: E=Se, M=Ir) and [M(eta6-p-cymene)[S2C2(B10H10)]] (p-cymene=4-isopropyltoluene; 3S: M=Ru; 4S: M=Os), with acetylene, propyne, and 3-methoxypropyne lead to the 18e complexes 5-19 with a metal-boron bond in each case. The reactions start with an insertion of the alkyne into one of the metal-chalcogen bonds, followed by B-H activation, transfer of one hydrogen atom from the carborane via the metal to the terminal carbon of the alkyne, and concomitant ortho-metalation of the carborane. The E-eta2-CC and the C(1)B units are arranged either cisoid or transoid at the metal. X-ray structural analyses are reported for one of the starting 16e complexes (4S), the cisoid complex 12S (from 2S and HC[triple bond]C-CH3), and the transoid complexes 9S and 14S (from 1S and HC[triple bond]C-CH2OMe, and from 3S and HC[triple bond]CH, respectively). All new complexes 5-19 were characterized by NMR spectroscopy (1H, 11B, 13C, and 77Se and 103Rh NMR spectroscopy when appropriate).

Metal-induced B-H activation: addition of methyl acetylene carboxylates to Cp*Rh-, Cp*Ir-, (p-cymene)Ru-, and (p-cymene)Os half-sandwich complexes containing the chelating 1,2-dicarba-closo-dodecaborane-1,2-dithiolate ligand

The reactions of the 16e half-sandwich complexes [Cp*M[S2C2(B10)H10)]] (1: M=Rh; 2: M = Ir) and [eta6-(4-isopropyltoluene)M[S2C2(B10H10)] (3: M=Ru; 4: M=Os) with both methyl acetylene monocarboxylate and dimethyl acetylene dicarboxylate were studied in order to obtain more evidence for B-H activation, ortho-metalation, and B(3,6)-substitution of the carborane cluster. In the case of rhodium, the reaction of 1 with methyl acetylene monocarboxylate led to new complexes after twofold insertion into one of the Rh-S bonds (7), and twofold insertion together with B-substitution at the carborane cage (8). In the case of iridium, the reactions of 2 with methyl acetylene monocarboxylate gave two geometrical isomers 10 and 11, in which the alkyne is inserted into one of the Ir-S bonds, followed by hydrogen transfer from the carborane via the metal to the former alkyne and formation of an Ir-B bond. Only one type each (12 and 13) of these isomers was obtained from the reactions of the ruthenium and osmium half-sandwich complexes 3 and 4. The 16e starting materials 1-4 reacted with dimethyl acetylene dicarboxylate at room temperature to give the complexes 14-17, respectively, which are formed by addition of the C=C bond to the metal center and insertion into one of the metal-sulfur bonds. The proposed structures in solution were deduced from NMR data (1H, 11B, 13C, 103Rh NMR), and X-ray structural analyses were carried out for the rhodium complexes 7 and 8.

Verbrückte Bis(fluorenyl)komplexe des zirconiums und hafniums als hochreaktive katalysatoren bei der homogenen olefinpolymerisation. Die molekülstrukturen von (C13H9C2H4C13H9) und (η5:η5-C13H8C2H4 C13H8)ZrCl2

The stepwise reaction of lithium fluorenyl and 1,2-dibromo-ethane gives 1,2-difluorenylethane (1). The reaction of 1 with MeLi (1:2) yields the dianion (C13H8C2H4C13H8)2− that can be reacted with MCl4 (M  Zr, Hf) to yield the ansa-metallocene complexes (C13H8C2H4C13H8)MCl2 (M  Zr (2), Hf (3)). The complexes 2 and 3 are the first ansa-bis(fluorenyl) complexes of a group 4 metal. Especially 2, in combination with methylaluminoxane (mao) shows an extremely high activity as a homogeneous ethylene polymerization catalyst. Compound 1 and complex 2 were characterized by X-ray diffraction studies.

The NMR-Spectroscopic and X-ray Crystal-Structural Characterization of Two Cp*Ir Halfsandwich Complexes Containing the 1,2-Dicarba-closo-dodecaborane-1,2-diselenolato Ligand

The reaction of [Cp*IrCl2](2) with dilithium 1,2-orthocarborane-1,2-diselenolate 3 leads to the green 16-electron diselenolene complex [Cp*Ir{Se2C2(B10H10)}] (4) which takes up two-electron ligands such as trimethylphosphane to give the 18-electron diselenolate derivative [Cp*Ir(PMe3)-{Se2C2(B10H10)}] (5). The molecular structures of 4 and 5 were determined by X-ray crystal structure analysis. The Se-77-nuclear shielding in 4 is lower by almost 500 ppm relative to that in 5.

The 16-electron dithiolene complexes (p-cymene)M[S2C2(B10H10)] (M=Ru, Os) containing both η6-(p-cymene) and η2-(ortho-carborane-dithiolate): adduct formation with Lewis bases, and X-ray crystal structures of (p-cymene)Ru[S2C2(B10H10)](L) (L=PPh3) and {(p-cymene)Ru[S2C2(B10H10)]}2(μ-LL) (LL=Ph2PCH2CH2PPh2 and N2H4)

Abstract The reaction of the η 6 -arene complexes [( p - cymene )MCl 2 ] 2 (M=Ru, Os; p - cymene =4-isopropyl–toluene) with dilithium 1,2-dicarba- closo -dodecaborane-1,2-dithiolate ( a ) leads to the new 16e dithiolene complexes ( p -c ymene )M[S 2 C 2 (B 10 H 10 )] (M=Ru ( 1 ), Os ( 1A )). Addition of monodentate Lewis bases (L) to 1 gives 18e dithiolate complexes of the type ( p - cymene )Ru[S 2 C 2 (B 10 H 10 )](L) (L=PPh 3 ( 2 ), P(OMe) 3 ( 3 ), NH 3 ( 4 ), NC 5 H 5 ( 5 ), CO ( 6 ), CN t Bu ( 7 ), SEt 2 ( 8 ), SC 4 H 8 ( 9 ), CN − ( 10 ) and SCN − ( 11 )), whereas bidentate bridging Lewis bases (LL) give centrosymmetric binuclear analogues, {( p - cymene )Ru[S 2 C 2 (B 10 H 10 )]} 2 (LL) (LL=Ph 2 PCH 2 CH 2 PPh 2 ( 12 ), N 2 H 4 ( 13 ) and 4,4′-dipyridine ( 14 )). The stability of the Lewis base adducts depends on the nature of the ligating atom and decreases in the order C>P>N>S>O. The adducts were characterized by their 1 H-, 13 C- and 11 B-NMR spectra, and X-ray crystal structures were determined for 2 , 12 and 13 . The phosphane ligands in 2 and 12 cause stronger folding of the planar dithiolene ring RuS 2 C 2 in 1 along the S⋯S vector (by 25.6° in 2 and 21.0° in 12 ) than the hydrazine ligand in 13 (7.5°).

The synthesis, characterization and polymerization behavior of ansa cyclopentadienyl fluorenyl complexes; the X-ray structures of the complexes [(C13H8)SiR2(C5H4)]ZrCl2 (RMe or Ph)

Abstract The preparation and characterization of the ansa metallocene complexes [(C 13 H 8 )ER 2 (C 5 H 4 )]ZrCl 2 , [(2,7- t Bu 2 C 13 H 6 )-SiR 2 (C 5 H 4 )ZrCl 2 and [(2,7- t Bu 2 C 13 H 6 )SiR 2 (C 13 H 8 )]ZrCl 2 (ESi or Ge; RMe or Ph) are reported The crystal structures of [(C 13 H 8 )SiR 2 (C 5 H 4 )]ZrCl 2 (RMe, or Ph) have been determined and are discussed. The complexes are compared in respect to their polymerization behavior of propylene.

(α-Diimine)nickel(II) complexes containing chloro substituted ligands as catalyst precursors for the oligomerization and polymerization of ethylene

(α-Diimine)nickel(II) dibromide complexes and their derivatives can be used for the polymerization and oligomerization of ethylene after activation with methyl-aluminoxane (MAO). The activities of these catalysts and the properties of the obtained polyethylenes depend on the structure of the used catalyst precursors. Therefore a variety of (α-diimine)nickel(II) dibromide complexes with chlorine and methyl substituents on the ligands and various substituents on the ligand backbone were studied as catalysts for the homogeneous polymerization of ethylene. The range of the polymerization products reaches from oligomers to polymers of low molecular weights.

Metal-induced BH activation. Addition of phenylacetylene to Cp*Rh-, Cp*Ir-, (p-cymene)Ru- and (p-cymene)Os halfsandwich complexes containing a chelating 1,2-dicarba-closo-dodecaborane-1,2-dichalcogenolate ligand

Abstract The addition reactions of the 16e halfsandwich complexes Cp*M[S 2 C 2 (B 10 H 10 )] ( 1S M=Rh, 2S M=Ir) and η 6 -(4-isopropyltoluene)M[S 2 C 2 (B 10 H 10 )] ( 3S M=Ru and 4S M=Os) with phenylacetylene lead selectively to the 18e complexes 5S – 8S , in which a metalboron bond is present and the phenylacetylene is regio- and stereoselectively inserted into one of the MS bonds, with one hydrogen atom transferred from the carborane cage to the terminal carbon of the alkyne, corresponding to ortho -metalation of the carborane cage. In all cases, the S-η 2 -(Ph)CC and the C(1)B units are linked to the metal in cisoid positions. The analogous reaction of Cp*Ir[Se 2 C 2 (B 10 H 10 )] 2Se with phenylacetylene gives 6Se . Complex 5S undergoes an intramolecular rearrangement in solution to the isomer 9S , where the RhB bond is cleaved, the B-atom now bearing the organic substituent, and a metalcarbon σ bond being formed together with a coordinative S→Rh bond. In contrast, the p -cymene complexes 7S and 8S rearrange into isomers 10S and 11S , in which the S-η 2 -(Ph)CC and the C(1)B(M) moieties occupy transoid positions, preventing further intramolecular rearrangements. The proposed structures in solution were deduced from NMR data ( 1 H-, 11 B-, 13 C-, 77 Se-, and 103 Rh-NMR) and X-ray structural analyses were carried out for 5S , 6Se , 9S and 10S .