Chromium(0) tricarbonyl complexes of 1,3,5-triazacyclohexanes

Abstract

Three 1,3,5-trialkyl-1,3,5-triazacyclohexane chromium tricarbonyl complexes fac-[Cr(CO) 3 (C 3 H 6 N 3 R 3 )] (R = Me, Et or Bu t ) have been prepared and their reactivities investigated. Both the kinetic and the thermodynamic stabilities of the complexes increase as the size of the R group increases. When R = Me or Et, the ligand is susceptible to displacement to produce [Cr(CO) 3 L 3 ] [L = pyridine or P(OMe) 3 ]. Room-temperature single crystal X-ray studies were carried out on the R = Me and Bu t complexes. Both molecules adopt the expected 'piano-stool' configuration with putative 3m symmetry; a crystallographic mirror plane passes through the methyl adduct. The Cr᎐N distances in the R = Me complex [2.153(3), 2 × 2.181(2) Å] are shorter than in the Bu t case [2.202(5) Ϫ 2.216(4) Å]; in both the substituents are obligate equatorial relative to the triazacyclohexane ring.

Activation of 1,3,5-trimethyl-1,3,5-triazacyclohexane by Os3(CO)12 to form amidino [(MeN)2CH] cluster complexes

“…The relative yields of 1, 2, and 3 are dependent on the reaction conditions. Such that, compound 2 is dominant (61% yield) in refluxing toluene (110°C) for 4 h, while compound 3 becomes the major product (56% yield) when the reaction time is extended to 20 h. On the other hand, no reaction occurs between Os 3 (CO) 12 and (MeNCH 2 ) 3 below 80°C, while the reaction of the acetonitrile-substituted labile cluster Os 3 (CO) 10 predominantly. Furthermore, heating 2 in toluene gives no reactions, but it readily degrades to form 3 in the presence of (MeNCH 2 ) 3 ligand.…”

“…Reaction of Os 3 (CO) 12 and (MeNCH 2 ) 3 in refluxing toluene leads to C-H and C-N bond activation of the triazacyclohexane ligand to afford the amidino complexes (l-H)Os 3 (CO) 10 [l,g 2 -CH(NMe) 2 ] (1), (l-H)Os 3 (CO) 9 [l 3 ,g 2 -CH(NMe) 2 ] (2), and Os 2 (CO) 6 [l,g 2 -CH(NMe) 2 ] 2 (3) (Scheme 1). The relative yields of 1, 2, and 3 are dependent on the reaction conditions.…”

“…Recently, we described that treatments of M 3 (CO) 12 (M = Fe, Ru) or Os 3 (CO) 11 (NCMe) with (MeNCH 2 ) 3 afforded the anionic hydrido clusters ½ðl-HÞM 3 ðCOÞ À 11 ½MeNðMeN-CH 2 Þ 2 CH þ via an unusual hydride-transfer process from the triazacyclohexane molecule [15]. In contrast, Os 3 (CO) 12 reacted with (MeNCH 2 ) 3 quite differently to yield amidino [CH(NMe) 2 ] cluster complexes. Presented in this paper are complete characterizations of the reaction products and information concerning their generation.…”

“…For example, M(CO) 6 (M = Cr, Mo, W) reacts with (MeNCH 2 ) 3 to produce M(CO) 3 [g 3 -(MeNCH 2 ) 3 ], which are good starting compounds for the preparation of a variety of organometallic derivatives [12][13][14]. Recently, we described that treatments of M 3 (CO) 12 (M = Fe, Ru) or Os 3 (CO) 11 (NCMe) with (MeNCH 2 ) 3 afforded the anionic hydrido clusters ½ðl-HÞM 3 ðCOÞ À 11 ½MeNðMeN-CH 2 Þ 2 CH þ via an unusual hydride-transfer process from the triazacyclohexane molecule [15]. In contrast, Os 3 (CO) 12 reacted with (MeNCH 2 ) 3 quite differently to yield amidino [CH(NMe) 2 ] cluster complexes.…”

Preparation of Complexes η4-4-(1,3-Diphenyl-2-propen-1-one)-η3-3-(1,3,5-triorganyl-1,3,5-triazacyclohexane)carbonyltungsten(0) and Their Reactions with Diethyl Phosphite

“…h 3 -[(1,3,5-Triphenyl)-1,3,5-triazacyclohexane]tricarbonyltungsten(0) (IIb) and its hydroxyethyl analog IIc we brought into reaction with chalcone under conditions of thermochemical initiation: the reaction of the a-enone with the metal complex was carried out in boiling acetonitrile solution [6,7]. According to published data [2,4] with the growing size of substituents attached to the nitrogen atoms of the trialkyltriazinanes increases the conformational rigidity of the ligands, and it stabilizes the organometallic compounds obtained therefrom. Therefore we expected to obtain a stable organometallic derivative in reaction of the heterodiene and (triazinane)tricarbonyltungsten containing sterically loaded phenyl substituents.…”