Synthesis and Some Coordination Chemistry of Phosphane-Difunctionalized Bis(amidinato)-Heavier Tetrylenes: A Previously Unknown Class of PEP Tetrylenes (E = Ge and Sn)

Abstract

The bis(amidinato)-heavier tetrylenes E(bzamP) 2 (E = Ge (2a) and Sn (2b); bzamP = N-isopropyl-N′-(diphenylphosphanylethyl)benzamidinate), which are equipped with one heavier tetrylene (germylene or stannylene) and two phosphane fragments (one on each amidinate moiety) as coordinable groups, have been synthesized from the benzamidinum salt [H 2 bzamP]Cl and GeCl 2 (dioxane) or SnCl 2 in 2:1 mol ratio. A preliminary inspection of their coordination chemistry has shown that their amidinate group can also be involved in the bonding with the metal atoms as tridentate ENP and tetradentate PENP′ coordination modes have been observed for the ECl(bzamP) 2 ligand of [Ir{κ 3 E,N,P-ECl(bzamP) 2 }(cod)] (E = Ge (3a) and Sn (3b); cod = η 4 -1,5-cyclooctadiene) and the E(bzamP) 2 ligand of [Ni{κ 4 E,N,P,P′-E(bzamP) 2 }] (E = Ge (4a) and Sn (4b)), which are products of reactions of 2a and 2b with [IrCl(cod)] 2 (1:0.5 mol ratio) and [Ni(cod) 2 ] (1:1 mol ratio), respectively. These products contain a 5-membered NCNEM ring that results from the insertion of the metal M atom into an E−N bond of 2a and 2b. Additionally, while iridium(I) complexes 3a and 3b are chloridotetryl derivatives (insertion of the tetrylene E atom into the Ir−Cl bond has also occurred) that have an uncoordinated phosphane group, nickel(0) complexes 4a and 4b contain a tetrylene fragment that, maintaining the lone pair, behaves as a σ-acceptor (Z-type) ligand.

Amidinatotetrylenes Donor Functionalized on Both N Atoms: Structures and Coordination Chemistry

“…Germylene 1a and stannylene 1b are potentially tridentate ligands featuring an AT in the central position. Such a type of tridentate ligands has only been recently reported by our group for the PEP bis(amidinato)tetrylenes E(bzamP) 2 (E = Ge, Sn; HbzamP = N-isopropyl-N′diphenylphosphanylethyl)benzamidine; see Figure 2, left), 34 which are inscribed in the also rare type V category.…”

“…In fact, only a few of these systems, particularly of type V, have been involved (as ligands) in coordination chemistry. They have so far led to complexes featuring κ 2 Ge,P-, 33 κ 3 E,N,P-, 34 and κ 4 E,N,P,P- 33,34 ligands (E = Ge, Sn). This work, prompted by the current lack of studies on the coordination chemistry of polydentate-ATs nondirectly donor functionalized on the tetrel atom (types III−V), adds an unexplored configuration to the field, describing the synthesis, characterization, and some coordination chemistry of E-(hmds)(bqfam) (E = Ge (1a), Sn (1b); see Figure 2, right).…”

“…In this regard, the metal complexes that are equipped with polydentate ATs have been generally prepared from metal-free ATs (generically E(R 1 NC(R 2 )NR 1 )X; E = heavier tetrel atom, X = anionic group; see Figure ) functionalized with at least one additional donor group (D). Figure shows the currently known types of metal-free potentially polydentate ATs, − which formally result from (a) attaching a donor fragment to the E atom (X position; type I ), − (b) connecting with a linker, which can also have additional donor or prone to undergo metalation groups, two ATs through their E atoms (X position; type II ), − through the amidinate central C atoms (R 2 position; type III ) − or through one of the two amidinate N atoms (R 1 position; type IV ), and (c) attaching a donor fragment to one of the N atoms (R 1 position; type V ). , By far, types I and II , whose syntheses normally imply an easy Cl replacement with an appropriate lithiated group on well-known chlorido-ATs, are the most explored donor-functionalized ATs, having led to a great variety of metal complexes fitted with κ 2 E , D -, − κ 2 E , E -, , κ 3 E , D , E -, κ 3 E , C , E - ligands, many of them with catalytic applications . On the other hand, the functionalization pathways that lead to types III , IV , and V , which imply modifications on the amidinate skeleton befor...…”

“…In fact, only a few of these systems, particularly of type V , have been involved (as ligands) in coordination chemistry. They have so far led to complexes featuring κ 2 Ge,P -, κ 3 E,N,P -, and κ 4 E,N,P,P- , ligands (E = Ge, Sn).…”

Polydentate Amidinato‐Silylenes, ‐Germylenes and ‐Stannylenes

“…The first specimens of this type have been very recently prepared in two steps from Nisopropylbenzimidoyl chloride, 2-(diphenylphosphanyl)ethylamine, LiN(SiMe 3 ) 2 (as deprotonating reagent) and GeCl 2 (dioxane) or SnCl 2 (Figure 20). [52]…”