Electronic structures of tetragonal nitrido and nitrosyl metal complexes

The standard oxidation states of central metal atoms in C _4v nitrido ([M(N)(L)₅] ^z ) complexes are four units higher than those in corresponding nitrosyls ([M(NO)(L)₅] ^z ) (L=CN: z = 3−, M = Mn, Tc, Re; z = 2−, M = Fe, Ru, Os; L = NH₃: z = 2+, M = Mn, Tc, Re; z = 3+, M = Fe, Ru, Os). Recent work has suggested that [Mn(NO)(CN)₅]³⁻ behaves electronically much closer to Mn(V)[b ₂(xy)]², the ground state of [Mn(N)(CN)₅]³⁻, than to Mn(I)[b ₂(xy)]²[e(xz,yz)]⁴. We have employed density functional theory and time-dependent density functional theory to calculate the properties of the ground states and lowest-lying excitations of [M(N)(L)₅] ^z and [M(NO)(L)₅] ^z . Our results show that [M(N)(L)₅] ^z and [M(NO)(L)₅] ^z complexes with the same z value have strikingly similar electronic structures.     

Substitution reaction of η5-cyclopentadienylruthenium(II) complexes with nitrogen,oxygen and sulfur donor ligands

The heterocycles pyridine, γ-picoline, 2,2′-bipyridine and 1,10-phenanthroline react with [(η⁵-C₅H₅)Ru(MPh₃)₂X] (M = P, As or Sb) and [(η⁵-C₅H₅)Ru(AsPh₃)(PPh₃)X] (X = Cl, Br, I, CN, NCS or SnCl₃) to form complexes of types [(η⁵-C₅H₅)(MPh₃)(L−L)⁺X⁻ (L−L = 2,2′−bipyridine or 1,10−phenanthroline; X = Cl, Br, I, CN, NCS or SnCl₃) and [(η⁵-C₅H₅)Ru(MPh₃)LX] (M = As or Sb; L = pyridine or γ-picoline; X = Cl, Br, I, CN, NCS or SnCl₃). Interactions of dithiocarbamate (DTC) with [(η⁵-C₅H₅)Ru(SbPh₃)₂X] (X = Cl, Br or I) and acetylacetonate (acac) with parent compounds [(η⁵-C₅H₅)Ru(MPh₃)₂X (M = P or Sb; X = Cl, Br or I) yielded [(η⁵-C₅H₅)Ru(MPh₃)L] (where L = DTC or acac). The reaction products have been characterized by magnetic, spectral and microanalytical data.     

The nature of the lowest excited state and photosubstitution reactivity of tetracarbonyl-1,10-phenanthrolinetungsten(0) and related complexes

Absorption and emission spectral studies of M(CO)₄L complexes (M = Cr Mo, W; L = 2,2′-bipyridine, 1,10-phenanthroline, 5-CH₃-, 5-Cl-, 5-Br-, 5-NO₂-1,10-phenanthroline) have been carried out and reveal that the lowest excited state in every case is charge-transfer (CT) in character, M→ CT in absorption, and in no case do the ligand field (LF) excited states cross below the CT state. Minimum energies of the LF states have been established by the spectroscopic study of cis-bis(pyridine)- and cis-bis(aliphatic amine)-tetracarbonylmetal(0) complexes which all have LF lowest excited states for M = Mo, W. For the M(CO)₄L complexes emission is detectable for M = Mo or W and occurs in the range 14.40-15.66 kK with lifetimes of 7.9-13.3 μsec and quantum yields of 0.02–0.09 all in EPA solution at 77 K. For the bis-pyridine and -aliphatic amine complexes emission occurs only from the W complexes and is of the order of 3.0–4.0 kK higher in energy than for the M(CO)₄L complexes. Photosubstitution of pyridine is efficient in cis-W(CO)₄(py)₂ (py = pyridine): Φ_436nm = 0.23; Φ_405nm = 0.27; and Φ_366nm = 0.23. The M(CO)₄L complexes have strongly wavelength dependent, but modest, quantum yields for CO substitution and show that the lowest CT state is unreactive. Typical values for CO substitution for M = W and L = 1,10-phenanthroline are: Φ_436nm = 1.6 × 10^?4; Φ_405nm = 1.2 × 10^?3; Φ_366nm = 9.2 × 10^?3; and Φ_313nm = 2.2 × 10^?2.     

Synthesis and characterisation of [AgL(μ-PR2)M(CO)5], L= 1,10-phenanthroline or tricyclohexylphosphine; M = Cr,Mo, W

The new heterobimetallic phosphide-bridged compounds [AgL(μ-PR₂)M(CO)₅], (L = 1,10-phenanthroline or tricyclohexylphosphine: M = Cr, M, W) have been prepared from AgO₃SCF₃, M(CO)₅PR₂H and the ligand L in the presence of Et₂NH or MeO⁻ as base, and characterized by ³¹P NMR spectroscopy.     

Kationische übergangsmetallkomplexe von thiazylbis-trifluormethylnitroxid

Thiazylbis-trifluoromethyl nitroxide (L = (CF₃)₂NOSN) acts as aσ-donor ligand towards cationic organometallic and simple transition metal centers to give the stable complexes [M(CO)₅L]⁺ (M = Mn, Re), ML₆²⁺ (M = Fe, Co, Ni) and ML₄²⁺ (M = Cu). The structure of [NiL₆](AsF₆)₂ has been determined and some of the properties of the ligand are discussed.     

A Mechanistic Study on Reactions of Group 13 Diyls LM with Cp*SbX2: From Stibanyl Radicals to Antimony Hydrides

Oxidative addition of Cp*SbX₂ (X=Cl, Br, I; Cp*=C₅Me₅) to group 13 diyls LM (M=Al, Ga, In; L=HC[C(Me)N (Dip)]₂, Dip=2,6-iPr₂C₆H₃) yields elemental antimony (M=Al) or the corresponding stibanylgallanes [L(X)Ga]Sb(X)Cp* (X=Br 1 , I 2 ) and -indanes [L(X)In]Sb(X)Cp* (X=Cl 5 , Br 6 , I 7 ). 1 and 2 react with a second equivalent of LGa to eliminate decamethyl-1,1’-dihydrofulvalene (Cp*₂) and form stibanyl radicals [L(X)Ga]₂Sb ^. (X=Br 3 , I 4 ), whereas analogous reactions of 5 and 6 with LIn selectively yield stibanes [L(X)In]₂SbH (X=Cl 8 , Br 9 ) by elimination of 1,2,3,4-tetramethylfulvene. The reactions are proposed to proceed via formation of [L(X)M]₂SbCp* as reaction intermediate, which is supported by the isolation of [L(Cl)Ga]₂SbCp ( 11 , Cp=C₅H₅). The reaction mechanism was further studied by computational calculations using two different models. The energy values for the Ga- and the In-substituted model systems showing methyl groups instead of the very bulky Dip units are very similar, and in both cases the same products are expected. Homolytic Sb−C bond cleavage yields van der Waals complexes from the as-formed radicals ([L(Cl)M]₂Sb ^. and Cp* ^. ), which can be stabilized by hydrogen atom abstraction to give the corresponding hydrides, whereas the direct formation of Sb hydrides starting from [L(Cl)M]₂SbCp* via concerted β-H elimination is unlikely. The consideration of the bulky Dip units reveals that the amount of the steric overload in the intermediate I determines the product formation (radical vs. hydride).     

Studies on ruthenium(III), rhodium(III) and iridium(III) complexes of indazoles

Summary New complexes of the general formula M(L)₃Cl₃ and M(5-AInz)₂Cl₃ · n H₂O (where M = Ru^III, Rh^III and Ir^III; L = indazole and 5-nitroindazole; n=1–2) have been synthesized and characterised by elemental analysis, molar conductance, magnetic susceptibility and i.r. and electronic spectral measurements. All the complexes are covalent and apparently have an octahedral geometry. The ligands are monocoordinated through the pyrrole nitrogen. From the far i.r. spectra amer configuration has been assigned to the indazole and 5-nitroindazole complexes.     

N-Heterocyclic Carbene Analogues of Nucleophilic Phosphinidene Transition Metal Complexes

Chloride abstraction from the complexes [(η⁶-p-cymene){(IDipp)P}MCl] ( 2 a , M=Ru; 2 b , M=Os) and [(η⁵-C₅Me₅){(IDipp)P}IrCl] ( 3 b , IDipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBAr^F) in the presence of trimethylphosphine (PMe₃), 1,3,4,5-tetramethylimidazolin-2-ylidene (^MeIMe) or carbon monoxide (CO) afforded the complexes [(η⁶-p-cymene){(IDipp)P}M(PMe₃)]BAr^F] ( 4 a , M=Ru; 4 b , M=Os), [(η⁶-p-cymene){(IDipp)P}Os(^MeIMe)]BAr^F] ( 5 ) and [(η⁵-C₅Me₅){(IDipp)P}IrL][BAr^F] ( 6 , L=PMe₃; 7 , L=^MeIMe; 8 , L=CO). These cationic N-heterocyclic carbene-phosphinidene complexes feature very similar structural and spectroscopic properties as prototypic nucleophilic arylphosphinidene complexes such as low-field ³¹P NMR resonances and short metal-phosphorus double bonds. Density functional theory (DFT) calculations reveal that the metal-phosphorus bond can be described in terms of an interaction between a triplet [(IDipp)P]⁺ cation and a triplet metal complex fragment ligand with highly covalent σ- and π-contributions. Crystals of the C−H activated complex 9 were isolated from solutions containing the PMe₃ complex, and its formation can be rationalized by PMe₃ dissociation and formation of a putative 16-electron intermediate [(η⁵-C₅Me₅)Ir{P(IDipp)}I][BAr^F], which undergoes C−H activation at one of the Dipp isopropyl groups and addition along the iridium-phosphorus bond to afford an unusual η³-benzyl coordination mode.     

Variable Bonding Modes of Pyrimidine‐2‐thione in PdII/PtII Complexes [M(η2‐N,S‐pymS)(η1‐S‐pymS)(PPh3)] and [M(η1‐S‐pymS)2(L‐L)] (L‐L = dppm,dppe)

Reactions of pyrimidine‐2‐thione (HpymS) with Pd^II/Pt^IV salts in the presence of triphenyl phosphine and bis(diphenylphosphino)alkanes, Ph₂P‐(CH₂)_m‐PPh₂ (m = 1, 2) have yielded two types of complexes, viz. a) [M(η²‐N, S‐ pymS)(η¹‐S‐ pymS)(PPh₃)] (M = Pd, 1 ; Pt, 2 ), and (b) [M(η¹‐S‐pymS)₂(L‐L)] {L‐L, M = dppm (m = 1) Pd, 3 ; Pt, 4 ; dppe (m = 2), Pd, 5 ; Pt, 6 }. Complexes have been characterized by elemental analysis (C, H, N), NMR spectroscopy (¹H, ¹³C, ³¹P), and single crystal X‐ray crystallography ( 1 , 2 , 4 , and 5 ). Complexes 1 and 2 have terminal η¹‐S and chelating η²‐N, S‐modes of pymS⁻, while other Pd/Pt complexes have only terminal η¹‐S modes. The solution state ³¹P NMR spectral data reveal dynamic equilibrium for the complexes 3 , 5 and 6 , whereas the complexes 1 , 2 and 4 are static in solution state.     

Die konjugative Verbrückung metallorganischer Reaktionszentren in Heterozweikernkomplexen [(OC)3ClRe(μ‐L)MCl(C5Me5)]+, M = Rh oder Ir ‐ Spektroskopische Konsequenzen reduktiver Aktivierung

The Conjugative Bridging of Organometallic Reaction Centers in Heterodinuclear Complexes [(OC)₃ClRe(μ‐L)MCl(C₅Me₅)]⁺, M = Rh or Ir ‐ Spectroscopic Consequences of Reductive Activation Heterodinuclear complexes [(OC)₃ClRe(μ‐L)MCl(C₅Me₅)](PF₆), M = Rh or Ir and L = 2, 5‐bis(1‐phenyliminoethyl)pyrazine (bpip), 3, 6‐bis(2‐pyridyl)‐1, 2, 4, 5‐tetrazine (bptz) or 2, 2′‐bipyrimidine (bpym), were synthesized via mononuclear rhenium compounds (L)Re(CO)₃Cl. The stepwise reductive activation under chloride dissociation was studied through cyclic voltammetry and spectroelectrochemistry in the range of CO stretching vibrations (IR), charge transfer absorptions (UV/Vis) and electron spin resonance (ESR) for paramagnetic intermediates of the mono‐ and heterodinuclear compounds. While complexes of bpip and bptz form one‐electron reduced radical intermediates [(OC)₃ClRe(μ‐L)MCl(C₅Me₅)] ^˙ , the compounds with bpym react under MCl‐dissociative two‐electron reduction directly to [(OC)₃ClRe(μ‐L)M(C₅Me₅)].     

Coordination and Hydroboration of Ru(II)-Borate Complexes: Dihydridoborate vs. Bis(dihydridoborate)

Treatment of [Cp*RuCl₂]₂, 1 , [(COD)IrCl]₂, 2 or [(p-cymene)RuCl₂]_2, 3 (Cp*=η⁵-C₅Me_5, COD= 1,5-cyclooctadiene and p-cymene=η⁶-ⁱPrC₆H₄Me) with heterocyclic borate ligands [Na[(H₃B)L], L₁ and L₂ ( L₁ : L=amt, L₂ : L=mp; amt=2-amino-5-mercapto-1,3,4-thiadiazole, mp=2-mercaptopyridine) led to the formation of borate complexes having uncommon coordination. For example, complexes 1 and 2 on reaction with L₁ and L₂ afforded dihydridoborate species [L^AM(μ-H)₂BHL] 4 – 6 ( 4 : L^A=Cp*, M=Ru, L=amt; 5 : L^A=Cp*, M=Ru, L=mp; 6 : L^A=COD, M=Ir, L=mp). On the other hand, treatment of 3 with L₂ yielded cis- and trans-bis(dihydridoborate) species, [Ru{(μ-H)₂BH(mp)}₂], cis- 7 and trans- 7 . The isolation and structural characterization of fac- and mer-[Ru{(μ-H)₂BH(mp)}{(μ-H)BH(mp)₂}], 8 from the same reaction offered an insight into the behaviour of these dihydridoborate species in solution. Fascinatingly, despite having reduced natural charges on Ru centres both at cis-and trans- 7 , they underwent hydroboration reaction with alkynes that yielded both Markovnikov and anti-Markovnikov addition products, 10 a – d .     

Zur kenntnis der chemie der metallcarbonyle und der cyanokomplexe in flüssigem ammoniak : XXXIII. Über die darstellung neuer carbamoylcarbonyl-komplexe aus bekannten und neuen kationischen carbonylverbindungen des mangans und rheniums

The covalent carbamoyl carbonyl compounds Re(CO)₅COHN₂, cis-M(CO)₄(L)CONH₂, M(CO)₃(L)₂CONH₂ and M(CO)₃(D)CONH₂ (M = Mn, Re; L = PPh₃, PEt₃; D = bipy, phen) are formed by reactions of the cationic complexes [Re(CO)₆]⁺, [M(CO)₅L]⁺, [M(CO)₄L₂]⁺ and [M(CO)₄D]⁺ (M = Mn, Re; L = PPh₃, PEt₃; D = bipy, phen) with liquid NH₃ with concomitant deprotonation: [M(CO)_6?nL_n]⁺ + 2 NH₃ → M(CO)_5?nL_nCONH₂ + NH₄⁺ (n = 0, 1, 2) and [M(CO)₄D]⁺ + 2 NH₃ → M(CO)₃(D)CONH₂ + NH₄⁺ The stability of the above-mentioned carbamoyl carbonyl complexes increases from the penta- to the tetra- to the tri-carbonyl derivatives. In all cases the rhenium compounds are much more stable than the corresponding manganese complexes. Whereas the carbamoyl compound Re(CO)₄(PEt₃)CONH₂ can be isolated by reaction of [Re(CO)₅PEt₃]⁺ with NH₃, the corresponding manganese complex undergoes Hofmann degradation of amides even at ?70°C to form HMn(CO)₄PEt₃ and NH₄NCO. The IR and some mass and ¹H NMR spectra of the new hexacoordinated carbamoyl carbonyl complexes are discussed and the reactions of these compounds with liquid NH₃, HCl and CH₃OH are described.     

Nucleophilic attack on bent molybdenum and tungsten metallocene complexes

Reactions of some [M(η⁵-C₅H₅)₂L₂]ⁿ⁺ complexes (M  Mo, W; L = ligand; n = 0, 1, 2) with NaBH₄ and LiAlH₄ are reported. New neutral and cationic hydride derivatives of the type [M(η⁵-C₅H₅)₂HL]^m+ (m = 0, 1) are described, in particular the six halohydride complexes [M(η⁵-C₅H₅)₂HX]. The deuteration studies were carried out, but the results do not lead to definite conclusions about the mechanism.     

Alkenylphosphane RPX2 und R2PX (X = NEt2, CI): IHRE funktion als einzähnige liganden und potentiell hemilabile chelatbildner in metall(0)-komplexen

Depending on reaction conditions various types of substitution products are obtained from (CO)₆M (M = Cr, Mo, W) and the ambidentate ligands L = RPX₂ and R₂PX (R = vinyl, allyl, 2-vinylphenyl, 2-allylphenyl; X = NEt₂, Cl, Br): (CO)₅ML, (CO)₄ML₂ or chelate compounds (CO)₄ML, in which L is coordinated via P and the olefinic bond. Reactions of coordinated ligands, leading to (CO)₅CrRPNEt₂Br and (CO)₅CrRPH₂ (R = 2-vinylphenyl) are reported. In some cases L (R = 2-Vinylphenyl; X = NEt₂) proves to be hemilabile on reaction of the complex (CO)₄CrL with Lewis bases. Thus, e.g. with CO at room temperature and normal pressure (CO)₅ML iwth P-bonded L is formed, from which the educts can be recovered by gentle warming. The NMR spectra (¹H, ¹³C, ³¹P) of the compounds are discussed.     

Darstellung,Eigenschaften und Molekülstrukturen von Komplexen des versteiften dreizähnigen Chelatliganden N,N′-Bis(diphenylphosphino)-2, 6-diaminopyridin mit MII - und M0-Übergangsmetallen [MII = Ni,Pd, Pt; M0 = Cr,Mo, W]

Preparation, Properties, and Molecular Structures of a Rigid Tridentate Chelate Ligand N, N′-Bis(diphenylphosphino)-2, 6-diaminopyridine with M^II and M⁰ Transition Metals [M^II = Ni, Pd, Pt; M⁰ = Cr, Mo, W] The reaction of chlorophenylphosphane and 2, 6-Diaminopyridine give N, N′-Bis-(diphenylphosphino)-2, 6-diaminopyridine (PNP). Two types of complexes [M(PNP)Cl]Cl · L (M = Ni, L = H₂O; M = Pd, L = C₂H₅OH; M = Pt) and mer-[M(PNP)(CO)₃] · 2 THF (M = Cr, Mo, W) have been prepared using PNP. These coordination compounds have been characterized by means of i.r., u.v., ³¹P and ¹H n.m.r. measurements. The determination of the molecular structure of the two triclinic substances mer-[Mo(PNP)(CO)₃] · 2 THF and [Ni(PNP)Cl]Cl · H₂O show that the octahedral Mo(d⁶) and the square planar nickel (d⁸) compounds contain a nearly planar tridentate chelate ring system (two fused five-membered rings of the type ) in which the observed bond distances are in accordance with a π electron delocalization effect. The observed gram susceptibility of the diamagnetic Ni(d⁸) compound remains unchanged between 293 and 410 K. The relative activation property for a homogenous catalytic standard hydrogenation reaction of styrene to ethylbenzene decreases in series of catalysts of type [M(PNP)Cl]Cl · L with M^II = Ni > Pd > Pt.     

Chirale Halbsandwich‐Pentamethylcyclopentadienyl‐Rhodium(III)‐ und Iridium(III)‐Komplexe mit Schiff‐Basen aus Salicylaldehyd und α‐Aminosäureestern [1]

Chiral Half‐sandwich Pentamethylcyclopentadienyl Rhodium(III) and Iridium(III) Complexes with Schiff Bases from Salicylaldehyde and α‐Amino Acid Esters [1] A series of diastereoisomeric half‐sandwich complexes with Schiff bases from salicylaldehyde and L‐α‐amino acid esters including chiral metal atoms, [(η⁵‐C₅H₅)(Cl)M(N,O‐Schiff base)], has been obtained from chloro bridged complexes [(η⁵‐C₅Me₅)(Cl)M(μ‐Cl)]₂ (M = Rh, Ir). Abstraction of chloride from these complexes with Ag[BF₄] or Ag[SO₃CF₃] affords the highly sensitive compounds [(η⁵‐C₅Me₅)M(N,O‐Schiff base]⁺X^? (M = Rh, Ir; X = BF₄, CF₃SO₃) to which PPh₃ can be added under formation of [(η⁵‐C₅Me₅)M(PPh₃)(N,O‐Schiff base)]⁺X^?. The diastereoisomeric ratio of the complexes ( 1 ‐ 7 and 11 ‐ 12 ) has been determined from NMR spectra.     

Utilization of LVO 2? species (L2? is a tridentate ONS donor) as an inorganic analogue of carboxylate group: A journey to a new domain of coordination chemistry

The anionic cis-dioxovanadium (V) complex species LVO ₂ ^- of tridentate biprotic dithiocarbazate-based ligands H₂L (S-methyl-3-((5-R-2-hydroxyphenyl)methyl)dithiocabazate, R = H, L = L¹; and R = Br, L = L²) can bind alkali metal ions. The products [LVO₂M(H₂O)_n] (M = Na⁺, L = L¹,1; L = L², 2 and M = K⁺, L = L¹,3) have extended chain structures in the solid state, stabilized by strong hydrogen bonding and Coulombic interactions as revealed from X-ray crystallography. The LVO ₂ ^- moieties here behave like analogues of carboxylate groups and display interesting variations in their binding patterns. It appears thatl is a single stranded helicate with LVO ₂ ^- units forming the strands which surround the labile sodium ions occupying positions on the axis. The compounds are stable in water and methanol as solvents, while in aprotic solvents of higher donor strengths, viz. CH₃CN, DMF and DMSO, they undergo photo-induced reduction when exposed to visible light, yielding green solutions from their initial yellow colour. The putative product is a mixed-oxidation (μ-oxo)divanadium (IV/V) species as revealed from EPR, electronic spectroscopy, dynamic¹H NMR, and redox studies.     

Studies ono-hydroxyacetophenone-2-furoylhydrazone complexes of some 3d-bivalent metal ions

Summary Complexes ofo-hydroxyacetophenone-2-furoylhydrazone, H₂L, of the types M(H₂L)C1₂ · nH₂O [Mn = Co^II, n=0; Ni^II, n=2]; Cu(HL)Cl, M(HL)₂ [M = V^IVO, Co^II, Ni^II or Cu^II] and M(L)(H₂O)_n [M = Co^II or Ni^II, n=2; M = Cu^II, n=0] have been prepared and characterized by elemental analyses, molar conductance, magnetic susceptibility, visible, e.s.r. and i.r. spectral studies. The different modes of ligand chelation and the stereochemistry around the metal ions are discussed.     

A carbon-13 NMR study of some metal carbonyl compounds containing one-electron ligands

Carbon-13 NMR spectral data for complexes having the general formula CpM(CO)_nX (Cp = η⁵-C₅H₅; M = Mo or W, n = 3; M = Fe, n = 2; X = halogen, methyl or acetyl) and their phosphine and isocyanide substitution products are reported. For CpM(CO)₃X complexes two carbonyl resonances (1 : 2 ratio) are observed in all cases, consistent with the retention of the “piano-stool” geometries observed in the solid state. Substituted complexes CpM(CO)₂(L)X (M = Mo or W; L = PR₃ or cyclohexyl isocyanide) are unequivocally assigned cis or trans geometries on the basis of the number of observed carbonyl resonances and values of ²J(PC) for the phosphine substituted derivatives. Spectral data for [M(CO)₅X]^? (M = Cr, Mo or W; X = Cl, Br or I) and η⁷-C₇H₇Mo(CO)₂X and the halide derivatives above generally show an increase in the shielding for carbonyls adjacent to the halide ligand in the order Cl < Br < I. Carbonyl resonances are more shielded in isostructural complexes in the order Cr < Mo < W (triad effect).     

Heterobimetallic Complexes: Substitution Effects in the [Tetracarbonylrhodiumbis{μ‐(diphenylphosphino)}{μ‐(η:η2‐(4‐diphenylphosphino‐κP)‐2‐methyl‐oxobutyl)}molybdenum](Mo‐Rh) System

Syntheses of the array of heterobimetallic complexes [(OC)₃M(μ‐PPh₂)₂(μ‐O‐C(CHMe(CH₂)₂PPh₂)RhL], M = Cr, Mo, W, L = ^tBuNC, are described, extending the previous study of the counterpart array for L = CO. A single crystal X‐ray structure determination is reported for the M = Mo adduct, enabling comparison with its previously reported L = CO counterpart, for which an improved redetermination is also reported. In the present complex the ^tBuNC ligand is found to be much more weakly bound (Rh‐C 2.026(5) Å) than the carbonyl group it displaces (Rh‐C 1.945(2) Å) with concomitant minor impact on the remainder of the rhodium ambience.