Mechanism of the reaction of [Mo(η-C₆H₆)(Me₂PCH₂CH₂PMe₂)(η-C₂H₄)H]⁺with PMe₃giving [Mo(η-C₆H₅Et)(dmpe)(PMe₃)H]⁺: metal-to-ring migration of an ethyl group

Abstract

Non-S.I. units employed: eV z 1.60 x J, atm = 101 325 Pa. Results and DiscussionSynthesis of New Compounds.-The study of the mechanism of reaction ( 2 ) necessitated the synthesis of several new compounds which will be described before the mechanistic studies. The analytical, mass, n.m.r., and i.r. spectroscopic data which characterise the new compounds are given in Table 1. These data are not discussed further except where the interpretation is not straightforward. The structures proposed for the new compounds are shown in the Schemes 1 4 .The q-toluene analogue of (l), namely [Mo(q-c,H,Me)-(dmpe)(q-C2H4)H]PF,, (4), was prepared in 60% yield by reduction of [Mo(q-C,H, Me)(dmpe)(q-C,H,)] PF, using sodium amalgam in the presence of ethylene, followed by the addition of aqueous NH,PF,.Treatment of compound (1) with trimethyl phosphite, carbon monoxide, or isocyano-2,6-dimethylbenzene gives the compounds trans-[M~(q-C,H,)(drnpe)(P(oMe)~}H]PF,, (5), t~Uns-[MO(~-C,H,)(dmpe)(co)H]PF,, (6), and tranS-[MO(q-C,H,)(dmPe)(2,6-Me,C,H,NC)HIPF,, (7), respectively (See Scheme 2). The formation of (5) is discussed in more detail below.[Mo(q-C6H6)(dmpe)(q-C2H4)HIPF6

Synthesis, structures and some reactions of Ru(CCCCFc)(PP)Cp (PP=dppm, dppe) and related compounds

“…Thus, the base-induced migration of organic (9) 2.042(8), 2.040(10); 2.041 (9) 2.030 (9), 2.019(5); 2.024 (9) 2.04 (1) (3) 2.047 (6) 2.007 (3) 2.028 (4) 2.059(3) Ru-C (1) 1.979 (4) 1.988 (3) 1.963 (10) 1.987 (6) 2.046 (3) 1.915 (4) 1.973 (3) 2.7324 (4) [I] C(1)-C(2) 1.225 (5) (2) fragments has been reported for systems such as Co(PMe 3 ) 2 Cp complexes bearing acyl groups [22] and transfer of SiMe 3 groups from iron [23] while similar reactions leading to amination of the Cp ring are known [24]. Extensive studies of arene-molybdenum complexes [25] and acyl-iron derivatives [26] have concluded that nucleophilic attack at the metal centre results in migration of the carbon ligand to the p-ring, followed by loss of H. A closely related example is the reaction between Ru-(C"CPh)(PPh 3 ) 2 Cp and C 2 (CO 2 Me) 2 to give RuCl-(PPh 3 ) 2 (g-C 5 H 4 C"CCO 2 Me) during which, however, some process akin to alkyne metathesis has also occurred [27], while more recently, Lo Sterzo [28] has found either palladium-or LiBu-induced migrations in several cyclopentadienyl-metal carbonyl alkyls. In the present transformation of 8 into 9, attack by iodide at the ruthenium centre prompts the migration of the alkynyl substituent to the C 5 ring.…”

Arene Insertion with Pincer-Supported Molybdenum-Hydrides: Determination of Site Selectivity, Relative Rates, and Arene Complex Formation

“…Unlike with alkenes, direct observation of arene insertion into metal-hydride bonds is rare with examples reported for cobalt, iron, and niobium . Little is known, for example, about the site selectivity for insertion of a substituted arene into a metal-hydride bond, i.e., if a C­(sp 2 )–C­(sp 2 )– H or a C­(sp 2 )–C­(sp 2 )– R bond of a monosubstituted arene C 6 H 5 R would insert preferentially.…”