Fluorination of Carbonyl Compounds using Molybdenum Hexafluoride
Molybdenum(VI) fluoride can be used as a fluorinating agent though not as popular as the selective DAST and Deoxyfluor as @Waylander noted. Molybdenum(VI) fluoride fall under the category of electrophilic fluorinating agent where it acts as a Lewis acid. The reaction is run in an inert solvent like $\ce{CH2Cl2}$ and a catalyst like boron trifluoride is used. The following is the reaction procedure taken from an e-book$\ce{^{[1]}}$. Also yield of various gem-difluorocarbonyl compounds from corresponding carbonyl compounds are listed:


  A solution of $\ce{MoF6}$ (102g, 0.49g) in anhydrous $\ce{CH2Cl2}$(500mL) is cooled at 20-30 C. While passing a gentle flow of $\ce{BF3}$ through the solution, the carbonyl compound(0.5g) is added in small portion. The mixture is stirred while warming upto rt. Anhyd. $\ce{NaF}$ and silica gel were added. After filtration, the solvent is distilled in vacuo. The residue is distilled/purified by chromatography.


Further, it is written that:


  In general, the yields are not that high due to the sensitivity of the
  reaction towards electronic and steric factors. Yield increase with
  the elctronic withdrawing group of the substituent of the substrate
  and decrease with the steric hindrance of the carbonyl group.
  $\ce{MoF6}$ attacks ether, amino, hydroxy, carboxy as well as
  $\ce{C=C}$ bonds. Ester, amide, cyano, nitro are inert towards the
  reagent. Halo substituent are not exchanged for fluorine.


The general reaction is given by$\ce{^{[2]}}$:



If a cyclic compound is used then R1 and R2 will be fused together.

If fluorination is proceeded at high temperature then catalyst is not needed. Aromatic carboxylic acids are converted into into gem-trifluoro derivatives without any catalyst.
Also, Aryl trifluoromethyl derivatives can also be obtained under less drastic conditions by fluorination of aromatic acid chlorides.

Now, the same reaction can be achieved by using DAST or Deoxylfluor and they are the more popular fluorinating reagent than $\ce{MoF6}$. Their reaction mechanism has been studied extensively. The mechanism is more or less similar than the mechanism achieved by $\ce{MoF6}$. The following is an explanation of the mechanism$\ce{^{[3]}}$(emphasis mine):


  The electronic effect of the substituent exerted a significant
  influence on the reactivities of benzophenones. The presence of an
  electron-withdrawing group is believed to facilitate the nucleophilic
  attack of the fluoride anion to the carbonyl group, causing more
  facile cleavage of the carbon–oxygen double bond. Among the
  benzophenone substrates examined, 4-nitrobenzophenone exhibited the
  highest reactivity and the corresponding gem-difluorinated product was
  obtained in 91% yield[...]


Notes and References


Houben-Weyl Methods of Organic Chemistry Vol. E 10b/1, 4th Edition Supplement: "Organo-Fluorine Compounds - Synthesis of Fluorinated Compounds I, Transformations of Fluorinated Compounds" by Bernd Baasner and Georg Thieme Verlag, 14-May-2014 (link)
http://reag.paperplane.io/00002051.htm#2
Ying Chang, Amit Tewari, Avi-Izak Adi, Chul sung Bae "Direct nucleophilic fluorination of carbonyl groups of benzophenones and benzils with Deoxofluor" Volume 64, Issue 42, 13 October 2008, Pages 9837-9842
DOI: https://doi.org/10.1016/j.tet.2008.08.009
https://www.alfa.com/media/docs/FluorinatingAgents.pdf
Direct carbonyl group attack can be avoided and α-fluorination of ketones can be achieved by using highly selective fluorinating agent, NFSI. α-fluorination of cyclohexanone has been observed.



Enantioselective Organocatalytic α-Fluorination of Cyclic Ketones
Piotr Kwiatkowski, Teresa D. Beeson, Jay C. Conrad, and David W. C. MacMillan
Journal of the American Chemical Society 2011 133 (6), 1738-1741
DOI: 10.1021/ja111163u