Synthesis and single-crystal x-ray study of the mononuclear dihapto-benzyne (dehydrobenzene) nickel(0) complex Ni(.eta.2-C6H4)[(C6H11)2PCH2CH2P(C6H11)2]. Insertion reactions with simple molecules and x-ray crystal structure of the nickelaindan complex Ni(CH2CH2C6H4-o)[(C6H11)2PCH2CH2P(C6H11)2]

Abstract

Sodium amalgam reduction of NiC1(C6H4Br-2)(Cy2PCHzCHzPCyz)-0.5THF (6) (Cy = cyclohexyl, C6H1,) gives a mononuclear nickel(0) complex, Ni(qz-C6H4)(Cy3PCHzCHzPCy2) (3), which has been characterized by microanalysis, by mass, infrared, and NMR ('H, ' C, 31P) spectroscopy, and by single-crystal X-ray structural analysis. Crystals of 3 are orthorhombic, space group Pbca, with a = 16.068 (1) A, b = 17.189 (1) A, c = 22.358 (1) A, and 2 = 8. The structure was solved by heavy-atom methods and refined by least-squares methods to R = 0.035 and R, = 0.055 for 4203 independent reflections. The molecule consists of a central nickel atom coordinated by a symmetric q2-benzyne ligand [Ni-C(l) = 1.870 (4) A, Ni-C(2) = 1.868 (4) A the coordination geometry being close to trigonal planar. The coordinated C-C bond length of 1.332 (6) k is significantly larger than those observed in alkyne complexes of zerovalent nickel and latinum. The remaining C-C bonds of the six-membered ring are almost equal in length (average 1.385 i), consistent with a delocalized aromatic structure for the benzyne ligand. Complex 3 reacts with iodine and methyl iodide at room temperature to give, respectively, the 2-iodophenyl and o-tolyl complexes NiI(C6H4Y-2)(CyzPCHzCHzPCyz) (Y = I (71, Me (8)). Carbon dioxide, ethylene, and dimethyl acetylenedicarboxylate insert into the nickel-benzyne bond of 3 to give the nickelacycles Ni(C6H4COO)-(CyzPCHzCH2PCyz) (lo), Ni(CH2CHzC6H4-o)(CyzPCHzCHzPCyz) (111, and Ni(C(C02Me)=C-(COzMe)C6~4-o)(CyzPCH~cH~Pcyz) (12), respectively, whereas diphenylacetylene displaces benzyne to give Ni(PhCd!Ph)(CyzPCHzCHzPCyz) (13). Crystals of 11 are monoclinic, space group P2,/n, with a = 15.792 (6) A, b = 17.471 (6) A, c = 12.104 (4) A, p = 104.09 ( 2 ) O , and 2 = 4. The structure was solvedand refined as for 3 to R = 0.070 and R, = 0.071 for 2379 independent reflections. The nickel atom is coordinated in an approximately planar arrangement by the bidentate di(tertiary phosphine) and by two carbon atoms of a five-membered, half-chair-shaped chelate ring, the Ni-C(ary1) and Ni-C(alky1) bond lengths being 1.951 (12) and 1.988 (12) A, respectively. , .

Short‐Lived Orthobenzyne Complexes with Early Transition Metals of Group IV. First Direct Characterization and Electronic Cartography by Coupling FVT/UV‐PES with Calculations

“…First, AIM analysis (Table ) suggests that two isomeric forms can describe these transient complexes (Scheme ), o ‐phenylene ( I ) or o ‐benzyne ( II ) forms, as often proposed for known stable orthobenzyne complexes , . The bond paths between the metal center and the C1 and C2 carbon atoms are consistent with the metallacyclic structure ( I ).…”

“…The complex Ni(η 2 ‐ c ‐C 6 H 4 )(cyc 2 PCH 2 CH 2 PCyc 2 ) has been characterized by mass spectrometry, infrared spectroscopy, NMR spectroscopy, and X‐ray diffraction by M. A. Bennett et al (Scheme f). The authors have shown that these complexes can insert carbon monoxide, ethylene, and dimethylacetylenedicarboxylate into a Ni–benzyne bond to form nickelacycles , . Since then, new complexes of nickel(0) containing η 2 ‐4,5‐difluorobenzyne Ni((1,2‐η)‐4,5‐R 2 C 6 H 2 )L have been prepared (L: 1,2‐bis(dicyclohexylphosphanyl)ethane or bis(triethyl)phosphine, R: H, F) and their monomeric structure has been evidenced by 13 C NMR and FAB‐MS .…”

A Computational Understanding of Solvent Effect on the Structure, Electronic, Thermochemical, and Spectroscopic Properties of Ni(η2-C6H4)(H2PCH2CH2PH2) Complex

“…From the theoretical values, it is found that the optimized Ni–P bond lengths are slightly larger than the experimental values . But, the optimized Ni–C bond lengths are slightly shorter than the experimental values.…”

“…Several bis(benzyne) complexes of niobium, tantalum, molybdenum, and tungsten have been isolated from the reaction of the hexaarylmetalate anions with an excess of aryllithium . Also, organometallic compounds such as NiL 2 (C 6 H 4 )(L = PCy 3 , PiPr 3 ; Cy = cyclohexyl, iPr = isopropyl) and the η 2 ‐benzyne (dehydrobenzene) nickel(0) complex Ni(η 2 ‐C 6 H 4 ) ((C 6 H 11 ) 2 PCH 2 CH 2 P(C 6 H 11 ) 2 ) have been synthesized. The structure and bonding of Ni(C 6 H 4– n F n )(CO) 2 C 6 H 4 = benzyne ( n = 1–4) complexes have been studied theoretically …”

Palladium-Catalyzed Cycloaddition Reactions of Arynes

“…However, this procedure is not applicable to nickel, platinum and palladium complexes because they undergo reductive elimination, rather than beta elimination. Complexes 31 and 32 have been prepared by sodium amalgam reduction of the corresponding s-complex 37, as shown in Scheme 6 [6,7,24]. Aryne complexes of late transition metals are very reactive towards both nucleophiles (amines, alcohols, water) and electrophiles (iodine).…”