Reactions of [Mo(≡CBr)(CO)₂{HB(pzMe₂)₃}] (pz = pyrazol-1-yl) with Amines: Synthesis of Amino, Pyridinium, and Thiolato Carbyne Complexes

Abstract

The reactions of the bromocarbyne complex [Mo(tCBr)(CO) 2 {HB(pzMe 2 ) 3 }] (pz ) pyrazol-1-yl) with a range of secondary and heterocyclic amines have been investigated and found in each case to proceed via simple nucleophilic halide substitution to provide N-functionalized carbyne derivatives, some of which are not available via conventional approaches. With diethylamine or piperazine the simple dialkyaminocarbyne complexes [Mo(tCNEt 2 )(CO) 2 {HB(pzMe 2 ) 3 }] or [Mo{tCN(C 2 H 4 ) 2 NH}(CO) 2 {HB(pzMe 2 ) 3 }] were obtained. With 4-N,N-dimethylaminopyridine the pyridiniumcarbyne salt [Mo(tCNC 5 H 4 NMe 2 -4)-(CO) 2 {HB(pzMe 2 ) 3 }]Br was obtained; pyridine provided a complex intractable mixture and collidine failed to react. N-Methylimidazole provided the imidazolium derivative [Mo(tCNC 3 H 3 NMe)-(CO) 2 {HB(pzMe 2 ) 3 }]Br, while N-(trimethylsilyl)imidazole gave the neutral imidazolyl derivative [Mo(tCNC 3 H 3 N)(CO) 2 {HB(pzMe 2 ) 3 }] and N,N′-bis(trimethylsilyl)imidazolium bromide. The sulfenamide HN(SPh) 2 afforded the thiolatocarbyne complex [Mo(tCSPh)(CO) 2 {HB(pzMe 2 ) 3 }] rather than the expected aminocarbyne complex [Mo{tCN(SPh) 2 }(CO) 2 {HB(pzMe 2 ) 3 }], while HN(PPh 2 S) 2 failed to react. The complex 1 is unreactive toward 1,8-diazabicycloundecene (DBU); however prolonged heating results in the formation of [DBUH][Mo(O) 3 {HB(pzMe 2 ) 3 }] via base-induced hydrolysis/oxidation.

Crystal structures of three anhydrous salts of the Lewis base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with the ring-substituted benzoic acid analogues 4-aminobenzoic acid, 3,5-dinitrobenzoic acid and 3,5-dinitrosalicylic acid

“…With the structures of (II) and (III), there is disorder in the six-membered ring system involving atoms C9A and C10A (with alternative minor occupancy sites C12A and C13A), giving similar site occupancy factors [SOF 0.735 (3)/0.265 (3) and 0.686 (4)/0.314 (4) for (II) and (III), respectively]. This feature is found in three other structures among the CSD set: the previously mentioned 2,6-di(tert-butyl)-4-nitrophenolate (SOF 0.60/0.40) (Lynch & McClenaghan, 2003); in the 8-bromoguanosine 8-bromoguanoside adduct salt (SOF = 0.63/0.37) (Saftić et al, 2012) and in the counter-cation of a bromocarbyne Mo complex (SOF = 0.83/0.17) (Cordiner et al, 2008).…”

Pnictogen‐Functionalised C1 Ligands: MC‐ARn (n=0, 1, 2, 3)

“…[83]OTf( Scheme22). In the absence of the strong trans influence of trans-hydride (78)o rs-alkynyl ligands (79)(80), the halide and five-coordinate speciese xhibit much shorter ruthenium-carbon (CP) distances, although there is some uncertainty in these parameters owing to positional disorder of the C Pa nd trans-ligand(if present). The structural and spectroscopic data are otherwise congruent with the other reported cyaphides.…”

“…In most cases, the archetypes post-date the corresponding nitrogen-basedl igands, however,i nc ontrast to phosphoniocarbynes, ammoniocarbynes L n MCNR 3 remain unknown. [80] Reactivity patterns fort hese ligand classes are becoming apparent and elaborate architectures have arisen throught heir chemical modification.A sh eavier analogues have been slowly discovered,f or example, [W( CAPh 2 )(CO) 2 (Tp*)] (A = N, P, As, Sb,B i),K [W(CPPh)(CO) 2 (Tp*)], [RuH(C P)(dppe) 2 ]a nd au ranium C As complex, it is tantalising to consider the existence of each of these ligandsb ased on the heavierp nictogens. It is as imple matter to replace the lighter pnictogen of these benchmark compounds with heavier elements in silico and in so doing, it becomes unsurprisingly apparent that the most significant variation occurs between nitrogen and phosphorus.…”

“…This review collates a substantial body of emerging work associated primarily with the organophosphorus ligand classes L n MCPR m ( m =0–3). In most cases, the archetypes post‐date the corresponding nitrogen‐based ligands, however, in contrast to phosphoniocarbynes, ammoniocarbynes L n MCNR 3 remain unknown [80] . Reactivity patterns for these ligand classes are becoming apparent and elaborate architectures have arisen through their chemical modification.…”

Arsinocarbyne reactivity

“…1 Cyanide and isocyanide ligands provide easy access to most known A = N complexes, although aminocarbynes 2 L n MuCNR 2 are also readily accessible via classical Fischer 3 and Schrock 4 synthetic protocols. Ammoniocarbynes L n MuCNR 3 + are surprisingly still unknown (besides those derived from N-heterocyclic amines 5 ) in contrast with phosphoniocarbynes L n MuCPR 3 + which are well-documented. The chemistry of other species where A = P has also developed rapidly in recent years.…”