Synthesis of carbyne complexes of chromium, molybdenum, and tungsten by formal oxide abstraction from acyl ligands

Dihydrobis(pyrazolyl)borate Alkylidyne Complexes of Tungsten

“…[14] The [15,16] The 2-xylyl derivative 1a has been pre-viously employed for the preparation of various ''half-sandwich'' alkylidyne complexes, although its synthesis was not described. [13] The chloro(pyridine)mesitylmethylidyne complex [W(ϵCC 6 H 2 Me 3 -2,4,6)Cl(CO) 2 (NC 5 H 5 ) 2 ] has recently been reported [14] -2,6 2a, C 6 H 2 Me 3 -2,4,6 2b) on the basis of spectroscopic data and a crystallographic study (vide infra) of 2a.…”

“…In a similar manner, the plane of the picoline ligand is approximately orthogonal (ca. 79°) to that of the alkylidyne, lying between the pyrazolyl rings of the H 2 B(pz) 2 (30) 1.977(9) WϪN (15) 2.201(6) WϪN (10) 2.204(6) WϪN (26) 2.378(5) C(1)ϪC (7) 1.416(9) C(1)ϪWϪC (28) 85.6(3) C(1)ϪWϪC (30) 87.9(3) C(28)ϪWϪC (30) 87.6(3) C(1)ϪWϪN (15) 100.5(2) C(28)ϪWϪN (15) 94.3(3) C(30)ϪWϪN (15) 171.5(2) C(1)ϪWϪN (10) 101.2(2) C(28)ϪWϪN (10) 173.1(3) C(30)ϪWϪN (10) 93.6(3) N(15)ϪWϪN (10) 83.6(2) C(1)ϪWϪN (26) 173.8(2) C(28)ϪWϪN (26) 88.9(3) C(30)ϪWϪN (26) 88.9(2) N(15)ϪWϪN (26) 82.88(19) N(10)ϪWϪN (26) 84.30 (18) C (7)ϪC (1) [33] where the WϪN bond trans to the strongly π-acidic maleic anhydride (ma) is longer (2.253 Å ) than that trans to CO (2.233 Å ). The WϪN(26) bond length of 2.378(5) Å seen here for 2a far exceeds those discussed above and is consistent with the lability demonstrated in reactions with CNRЈ and PMe 2 Ph and also its facile isomerism.…”

Carben- und Carbin-Komplexe des Technetiums und Rheniums - Synthese, Struktur und Reaktionen / Carbene and Carbyne Complexes of Technetium and Rhenium - Synthesis, Structure and Reactions

“…So führt die Um set zung von 2 b mit Oxalylbromid in C H 2C12 bei -6 0 °C direkt zum Carbin-Komplex [Cp*(CO)2-R e=C P h]B r (5b), welcher nach chrom atographi scher Reinigung an silanisiertem Kieselgel bei -3 0 °C mit 80% Ausbeute als leuchtend-gelber, in C H 2C12 sehr gut, in Pentan dagegen unlöslicher Feststoff isoliert wird (Gl. (4) (4) Die Um wandlung von 2 b in 5 b, welche formal einer Oxid-A bstraktion aus einem Acyl-Liganden entspricht [10], lehnt sich an die von A. Mayr ent wickelte Direktsynthese von neutralen CarbinKomplexen des Typs rrans-X(CO)4M = C R (X = CI, Br; M = Cr, Mo, W; R = Alkyl, Aryl, Amino) aus Acylcarbonylmetallaten und Säurenhalogeni den an [11].…”

Hexacarbonyls and Carbonyl Complexes of Carbon σ-Bonded Ligands of Chromium, Molybdenum and Tungsten

“…An alternative approach involving the reaction o f metal acyl complexes with Lewis acids such as C 2 O 2 X 2 (X = Cl or Br) offers considerable flexibility and scope (Equation (65)). 605 The products are transformed conveniently into more stable species by the addition of donor ligands L (Equation (66); L 2 = py 2 , bipy or TMEDA). The use of (CF 3 CO) 2 O in place o f C 2 O 2 X 2 affords O 2 CCF 3 derivatives (Equation (67)).…”

“…A common way to prepare substituted derivatives o f [MX(CO) 4 (=CR)] is to proceed via reasonably stable derivatives [MX(CO) 2 L 2 (=CR)] in which the ligands L are themselves very labile to substitution. Thus, the pvridine ligands of the complex [WX(CO) 2 (py) 2 (sCNEt 2 )] are easily replaced by dppe,605 dmpe,627 bipy/ 27 2PMe 3 605 2P(OMe) 3 629 or 2CNR (R = Me or Bu 1 ) 633. In the last case, the remaining carbonyl groups are still liable to substitution.…”