The Interplay of Bis(tricarbido) and Dimetallaoctatetrayne Complexes of Platinum

Abstract

Non-interconvertible platinum bis(tricarbidotungsten) and dimetallaoctatetrayne π-complexes arise from the reactions of bis(tricarbidotungsten)mercurials and aurates with complexes of platinum(0) and platinum(II). Thus [PtCl 2 (PPh 3 ) 2 ] with either [Hg{C 3 W(CO) 2 (Tp*)} 2 ] or PPN[Au-{C 3 W(CO) 2 (Tp*)}] (Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate) affords both cis-[Pt{C 3 W-(CO) 2 (Tp*)} 2 (PPh 3 ) 2 ] and [(Tp*)(CO) 2 WC 6 W(CO) 2 (Tp*)], while the latter with [Pt(C 2 H 4 )(PPh 3 ) 2 ] affords the π-complex [Pt{η 2 -(Tp*)(CO) 2 WC 6 W(CO) 2 (Tp*)}(PPh 3 ) 2 ], which does not convert to the bis(tricarbido) isomer. Although an intermediate bis(tricarbidotungsten) complex [Pt{C 3 W(CO) 2 -(Tp*)} 2 (dppe)] (dppe = 1,2-bis(diphenylphosphine)ethane) may be spectroscopically observed to form in the related reaction employing [PtCl 2 (dppe)], this is unstable, ultimately and exclusively evolving to the free dimetallaoctatetrayne. The reaction of [Pt(C 2 H 4 )(PPh 3 ) 2 ] with [Hg{C 3 W(CO) 2 -(Tp*)} 2 ] provides a ca 3:2 mixture of cis-[Pt{C 3 W(CO) 2 (Tp*)} 2 (PPh 3 ) 2 ] and [Pt{η 2 -(Tp*)(CO) 2 WC 6 -W(CO) 2 (Tp*)}(PPh 3 ) 2 ] in addition to traces of [(Tp*)(CO) 2 WC 6 W(CO) 2 (Tp*)]. Circumstantial evidence is presented to suggest that the mercuric chloride liberated in the transmetalation reaction plays a role in subsequent transformations.

Flexible Platinum(0) Coordination to a Ditungsten Ethanediylidyne

“…Addition of [Pt(h-C 2 H 4 )(PPh 3 ) 2 ]t o the same tetrayne results in coordination of one "Pt(PPh 3 ) 2 " unit to one C Cb ond. [12] These results further substantiate the need for simultaneous platinum coordination to both W Cu nits (as in 4)t oaccount for its mobility in 2 and 3.…”

“…Upon treatment with [Pt(nbe) 3 ]/COD, an inseparable mixture of adducts arises with either one or two “Pt(COD)” appendages which do not, however, migrate between W≡C termini. Addition of [Pt(η‐C 2 H 4 )(PPh 3 ) 2 ] to the same tetrayne results in coordination of one “Pt(PPh 3 ) 2 ” unit to one C≡C bond . These results further substantiate the need for simultaneous platinum coordination to both W≡C units (as in 4 ) to account for its mobility in 2 and 3 .…”

“…[17] Insets = Views orthogonalt ot he platinum coordination plane, along the C3-O1 axis and space-fillingrepresentation. Selected bond lengths []and angles [8 8]: W2-Pt 2.9446(5), W1-Pt 2.9519(5), W2-C2 1.956(8), Pt-C1 2.113(7), Pt-C2 2.157(8), C1-C2 1.297 (12), Pt-C6 2.559(9), Pt-C4 2.592(10), Pt-C3 1.887 (11);C2-C1-W1 165.9(6), C1-C2-W2 161.0(7).…”

Metal coordination to a dimetallaoctatetrayne

“…17 It is nevertheless presumed that the initial site of coordination of the Co2 units is across the two internal C≡C bonds, followed by subsequent migration upon decarbonylation of the group 6 metal centres. 6), C3-C4 1.433(5), C4-C5 1.364(5), C5-C6 1.391(5), C6-W2 1.862(4), C2-Co1 2.003(4), C2-Co2 1.993(4), C3-Co1 1.980(4), C3-Co2 1.970(4), C4-Co3 1.967(4), C4-Co4 1.985(4), C5-Co3 1.991(4), C5-Co4 2.001(4), Co1-Co2 2.4582 (10), Co3-Co4 2.4623(9), W1-C1-C2 168.2(3), C1-C2-C3 149.9(4), C2-C3-C4 142.6(4), C3-C4-C5 143.0(4), C4-C5-C6 150.9(4), C5-C6-W2 165.9(3). Inset: Two alternate views of the WC6(Co)4W chain and space-filling representation.…”

The Odd Bit of Carbon

“…[5][6][7][8] The uncertainty as to whether the silypropargylidyne=TBAF combination would perform as [L n MC-CC-H] or [L n MC-CC] -could be overcome by the synthesis of crystalline gold [7] or mercury [8] tricarbido derivatives, which serve as tricarbido transmetallating agents towards rhodium, [9] ruthenium, [10] iridium [11] and platinum complexes (Scheme 2). [12] Scheme 1. Synthesis of bimetallic tricarbido complexes via fluoride mediated protodesilylation of propargylidynes (selected examples).…”