Synthesis and Structure of 1,2,3,4,5-Pentamethylcyclopentadienyl-1,4-Diphenyltetraazabutadiene Complexes of Rhodium and Iridium

Paek ,Cheolki,Ko, Jaejung,Kang, Sangook,Patrick J.Carrol Korean Chemical Society 1994 Bulletin of the Korean Chemical Society Vol.15 No.6

Monomeric rhodium and iridium-diaryltetrazene complexes $Cp^*$M(RNN=NNR)($Cp^*$=1,2,3,4,5-pentamethylcyclope ntadienyl; M=Rh, Ir; R=Ph, 4-tolyl) have been synthesized from [$Cp^*MCl_2]_2$(M=Rh, Ir) and 2 equiv. of $[Li(THF)_x]_2(RN_4$R) in benzene. We have determined the crystal structure of (${\eta}^5$-pentamethylcyclopentadienyl)diphenyltetrazene iridium by using graphite-monochromated Mo-$K_a$ radiation. The compound was crystallized in the monoclinic space group $P2_{1/c}$ with a=13.781(3), b=9.035(l), c=17.699(3) ${\AA}$, and ${\beta}=111.93(l)^{\circ}$. An X-ray crystal structure of complex 1 showed a short N(2)-N(3) distance ($1.265 {\AA}$) consistent with the valence tautomer A with Ir(III) rather than Ir(I). All complexes are highly colored and decompose on irradiation at 254 nm. Electrochemical studies show that complex 1 displays a quasi-reversible reduction.

A new and selective cycle for dehydrogenation of linear and cyclic alkanes under mild conditions using a base metal

Solowey, Douglas P.,Mane, Manoj V.,Kurogi, Takashi,Carroll, Patrick J.,Manor, Brian C.,Baik, Mu-Hyun,Mindiola, Daniel J. Nature Publishing Group 2017 Nature chemistry Vol.9 No.11

Selectively converting linear alkanes to α-olefins under mild conditions is a highly desirable transformation given the abundance of alkanes as well as the use of olefins as building blocks in the chemical community. Until now, this reaction has been primarily the remit of noble-metal catalysts, despite extensive work showing that base-metal alkylidenes can mediate the reaction in a stoichiometric fashion. Here, we show how the presence of a hydrogen acceptor, such as the phosphorus ylide, when combined with the alkylidene complex (PNP)Ti=CH<SUP>t</SUP>Bu(CH<SUB>3</SUB>) (PNP=N[2-P(CHMe<SUB>2</SUB>)<SUB>2</SUB>-4-methylphenyl]<SUB>2</SUB><SUP>−</SUP>), catalyses the dehydrogenation of cycloalkanes to cyclic alkenes, and linear alkanes with chain lengths of C<SUB>4</SUB> to C<SUB>8</SUB> to terminal olefins under mild conditions. This Article represents the first example of a homogeneous and selective alkane dehydrogenation reaction using a base-metal titanium catalyst. We also propose a unique mechanism for the transfer dehydrogenation of hydrocarbons to olefins and discuss a complete cycle based on a combined experimental and computational study.

Synthesis and Structure of $\eta^4$-1-Functionally Substituted-2,3,4,5-Tetraphenyl-1-Silacyclopentadienyl Complexes of Irontricarbonyl. Crystal Structure of ($\eta^4$-exo-Cyclopentadienyldicarbonyliron-endo-1-Methyl-2,3,4,5-Tetraphenyl-1-Silacyclopentadi

Jinkook Kang,Jaejung Ko,Youngkun Kong,Chang Hwan Kim,Myong Euy Lee,Patrick J. Carroll Korean Chemical Society 1992 Bulletin of the Korean Chemical Society Vol.13 No.5

New silicon-monosubstituted (${\eta}^4$-2,3,4,5-tetraphenyl-1-silacyclopentadiene)transi tion metal complexes are described. The new (silole-transition metal complex)Fe$(CO)_3$ was obtained from the reaction of silole-tansition metal complex and Fe$(CO)_5$. We have determined the crystal structure of (${\eta}^4$-exo-cyclopentadienyldicarbonyliron-endo-1-meth yl-2,3,4,5-tetraphenyl-1-silacyclopentadienyl)tric arbonyliron by using graphitemonochromated Mo-$K_{\alpha}radiation. The compound was crystallized in the monoclinic space group $P2_1$/c with a = 8.925(1), b = 18.689(3), c = 19.930(3) ${\AA}$, and ${\beta}$ = 102.02$(1)^{\circ}$. The iron moiety CpFe$(CO)_2$ on silicon is in an axal position. The (silole-transition metal complex) Fe$(CO)_3$ was also prepared through the reaction of (${\eta}^4$-1-chloro-2,3,4,5-tetraphenylsilacyclopentadiene) Fe$(CO)_3$ and metal complex nucleophile. The structure configuration was studied by conventional spectroscopy.

Room temperature olefination of methane with titanium–carbon multiple bonds

Kurogi, Takashi,Won, Joonghee,Park, Bohyun,Trofymchuk, Oleksandra S.,Carroll, Patrick J.,Baik, Mu-Hyun,Mindiola, Daniel J. Royal Society of Chemistry 2018 Chemical Science Vol.9 No.13

<▼1><P>C–H activation of methane followed by dehydrocoupling at room temperature led ultimately to the formation of the olefin H<SUB>2</SUB>C 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 CH<SUP><I>t</I></SUP>Bu <I>via</I> the addition of redox-active ligands (L) such as thioxanthone or 2,2′-bipyridine (bipy) to (PNP)Ti 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 CH<SUP><I>t</I></SUP>Bu(CH<SUB>3</SUB>) (<B>1</B>).</P></▼1><▼2><P>C–H activation of methane followed by dehydrocoupling at room temperature led ultimately to the formation of the olefin H<SUB>2</SUB>C 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000

Room-Temperature Ring-Opening of Quinoline, Isoquinoline, and Pyridine with Low-Valent Titanium

Baek, Seung-yeol,Kurogi, Takashi,Kang, Dahye,Kamitani, Masahiro,Kwon, Seongyeon,Solowey, Douglas P.,Chen, Chun-Hsing,Pink, Maren,Carroll, Patrick J.,Mindiola, Daniel J.,Baik, Mu-Hyun American Chemical Society 2017 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.139 No.36

<P>The complex (PNP)Ti=(CHBu)-Bu-t((CH2Bu)-Bu-t) (PNP = N[2-P(i)p(r2)-4-methylphenyl](2-)) dehydrogenates cyclohexane to cyclohexene by forming a transient low-valent titanium-alkyl species, [(PNP)Ti((CH2Bu)-Bu-t)], which reacts with 2 equiv of quinoline (Q) at room temperature to form (H3CBu)-Bu-t and a Ti(IV) species where the less hindered C-2=N-1 bond of Qis ruptured and coupled to another equivalent of Q, The product isolated from this reaction is an imide with a tethered cycloamide group, (PNP)Ti=N[C18H13N] (1). Under photolytic conditions, intramolecular C-H bond activation across the imide moiety in 1 occurs to form 2, and thermolysis reverses this process. The reaction of 2 equiv of isoquinoline (Iq) with intermediate [(PNP)Ti((CH2Bu)-Bu-t)] results in regioselective cleavage of the C-I=N-2 and C-1-H bonds, which eventually couple to form complex 3, a constitutional isomer of 1. Akin to 1, the transient [(PNP)Ti((CH2Bu)-Bu-t)] complex can ring-open and couple two pyridine molecules, to produce a close analogue of 1, complex (PNP)Ti=N[C10H9N] (4). Multinudear and multidimensional NMR spectra confirm structures for complexes 1-4, whereas solid-state structural analysis reveals the structures of 2, 3, and 4. DFT calculations suggest an unprecedented Mechanism for ring-opening of Q wheat the reactive intermediate in the low-spin manifold crosses over to the high-spin surface to access a low-energy transition state but returns to the low-spin surface immediately. This double spin-crossover constitutes a rare example of a two-state reactivity, which is key for enabling the reaction at room temperature. The regioselective behavior of Iq ring-opening is found to be due to electronic effects, where the aromatic resonance of the bicycle is maintained during the key C-C coupling event.</P>

C-H Bond Addition across a Transient Uranium-Nitrido Moiety and Formation of a Parent Uranium Imido Complex

Mullane, Kimberly C.,Ryu, Ho,Cheisson, Thibault,Grant, Lauren N.,Park, Ji Young,Manor, Brian C.,Carroll, Patrick J.,Baik, Mu-Hyun,Mindiola, Daniel J.,Schelter, Eric J. American Chemical Society 2018 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.140 No.36

<P>Uranium complexes in the +3 and +4 oxidation states were prepared using the anionic PN<SUP>-</SUP> (PN<SUP>-</SUP> = (<I>N</I>-(2-(diisopropylphosphino)-4-methylphenyl)-2,4,6-trimethylanilide) ligand framework. New complexes include the halide starting materials, (PN)<SUB>2</SUB>U<SUP>III</SUP>I (<B>1</B>) and (PN)<SUB>2</SUB>U<SUP>IV</SUP>Cl<SUB>2</SUB> (<B>2</B>), which both yield (PN)<SUB>2</SUB>U<SUP>IV</SUP>(N<SUB>3</SUB>)<SUB>2</SUB> (<B>3</B>) by reaction with NaN<SUB>3</SUB>. Compound <B>3</B> was reduced with potassium graphite to produce a putative, transient uranium-nitrido moiety that underwent an intramolecular C-H activation to form a rare example of a parent imido complex, [K(THF)<SUB>3</SUB>][(PN)U<SUP>IV</SUP>(═NH)[<SUP><I>i</I></SUP>Pr<SUB>2</SUB>P(C<SUB>6</SUB>H<SUB>3</SUB>Me)N(C<SUB>6</SUB>H<SUB>2</SUB>Me<SUB>2</SUB>CH<SUB>2</SUB>)]] (<B>4</B>). Calculated reaction energy profiles strongly suggest that a C-H insertion becomes unfavorable when a reductant is present, offering a distinctively different reaction pathway than previously observed for other uranium nitride complexes.</P> [FIG OMISSION]</BR>