Reactivity of the metalmetal-multiple bond in metal carbonyl derivatives

Abstract

The latter compound contains a bridging isonitrile ligand of fluxionial behavior as proved by high temperature 'H NMR spectroscopy. The u + B bonded character of the isonitrile bridge was established by X-ray c~st~o~aphy.Much attention has been paid to the addition of small donor molecules to the formally unsaturated [C,H,Mo(CO), I2 [2]. Careful investigations have been carried out recently on the symmetrical addition of allenes [3]. In contrast, relatively little is known about the reaction with heteroallenes, X=C=Y. As a first example we showed that (C~R~)~M~(CO)~ (R = H, CH,) reacts with boiling S=C=S to give complexes of the type CSR,(CO),Mo-Mo(CO),(q'-CS,)C~R~, containing a nonbridging, terminal q2-CS, ligand [4]. Stimulated by this result, we are using other heteroallenes, e.g. isothiocyanates and carbodiimides. In this paper we report on the reaction of [C+Me,(CO),Mo], with CH,N=C=S. Ex~~mentaI sectionAll procedures were carried out under nitrogen with solvents freshly distilled under nitrogen from appropriate drying agents. I was prepared according to a published procedure [5], CH,NCS was obtained from Fluka.

Reactions of Cyclohexyl Isocyanide with η5‐Substituted Cyclo‐pentadienyl MoMo Triply Bonded Complexes. Crystal Structure of [Mo(CO)2(η5‐C5H4CO2CH3)]2(μ‐η2‐CNC6H11)

“…In accordance with this type of structures, the ν (N≡C) values of the coordinated isocyanide appear in the range 1900-2125 cm -1 . However, in the case with a smaller steric hindrance situation, the isocyanide favors as a bridging ligand (Figure 1b and 1c), in which the C≡N bond lengths are longer and the ∠Mo1-C-N and ∠C-N-R are smaller than those in the above mentioned terminally coordinated complexes shown in Figure 1a, such as in complexes Mo 2 (CO) 4 (C 5 Me 5 ) 2 (CF 3 NC), 19 Mo 2 (CO) 4 -(C 5 Me 5 ) 2 (CF 3 CH 2 NC) 20 ( Figure 1b), and in complexes Mo 2 (CO) 4 (C 5 H 5 ) 2 (PhNC), 11,21 Mo 2 (CO) 4 (C 5 Me 5 ) 2 -(CH 3 NC), 22 Mo 2 (CO) 4 (C 5 H 5 ) 2 (t-BuNC), 12 Mo 2 (CO) 3 -(C 5 H 5 ) 2 (dppm)(t-BuNC), 23 and Mo 2 (CO) 2 (C 5 H 5 ) 2 (NPh)-(PhNC) (Figure 1c). 24 In addition, the ν (N≡C) values in these complexes are in the range 1600-1750 cm -1 .…”

Cyclopentadienyl Complexes of Chromium, Molybdenum and Tungsten

“…With certain reagents, however, such as tetraalkyl thiuram disulfides, fragmentation of the dimolybdenum structure occurs. 86 ' 101 ' 102 The reactions o f [M 2 (CO) 4 Cp 2 ] and their Cp* analogues with diazoalkanes have been extensively studied by the groups o f Herrmann and Curtis; as shown in Scheme 4 (alkyl diazoalkanes) and Scheme 5 (aryl diazo compounds), a wide variety of products can be isolated depending on both the metal complex employed and the substituents on the diazoalkane, with little apparent correlation. 103 " 16 Only in a f e w cases is the simple incorporation o f a carbene ligand and elimination o f N 2 observed; more often the nitrogen is retained in the product.…”

“…1066 Treatment of [M 2 (CO) n Cp 2 ] (M = Mo, W; n = 4 or 6) with RNCS or thiuram disulfides also gives the same dithiocarbamate complexes. 86 ' 101 ' 1067 Monodentate [W(V-SCSNMe 2 )(CO) 3 Cp] was isolated as an intermediate; 1068 it forms an adduct with [W(CO) 5 (THF)] but transfers the dithiocarbamate ligand to iron or manganese carbonyls. 1069 Related complexes with S 2 CPh and S 2 P(OPr i ) 2 ligands can be made by the action of Zn(S 3 CPh) or PtOPr^SXSH) on [Mo 2 (CO) 6 Cp 2 ].…”

Reactivity of the metal-metal multiple bond in metal carbonyl derivatives

“…In contrast, reactions of II proceeding without metal-metal bond scission seem so far to be restricted to those involving small molecules. Thus, CO [3], CS, [4], and diazoalkanes [5] gave addition products, as did Me-N=C=S, reaction of which resulted, after sulfur abstraction, in the formation of a p,ql : q*-isocyanide adduct [6]. A completely novel type of reaction which has so far been observed to occur only with II, is the replacement of all four carbonyl ligands by elemental sulfur [7] or selenium [8].…”